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1
Molokwanne, P. E., et E. M. N. Chirwa. « Biological Cr(VI) reduction in indigenous sludge cultures from Gauteng, South Africa ». Water Science and Technology 54, no 10 (1 novembre 2006) : 177–84. http://dx.doi.org/10.2166/wst.2006.880.
Texte intégralRésumé :
The Cr(VI) reducing capability of an acclimated indigenous culture cultivated from primary sludge was evaluated in batch and packed-bed bioreactor systems. Performance evaluation was carried out in unmodified cultures, cultures modified by substituting terminal organisms in the consortium by a known Cr(VI)-reducing organism (Escherichia coli ATCC 33456), and pure cultures of Cr(VI)-reducing organisms. A high Cr(VI) reduction rate was observed in modified cultures and in the pure culture of the Cr(VI)-reducing bacteria (Bacillus sp.). Furthermore, the Bacillus sp. pure culture outperformed both the unmodified and modified consortium cultures in reducing Cr(VI). Abiotic Cr(VI) reduction activity was evaluated in heat-killed and azide (N3−) inactivated control cultures. No significant Cr(VI) reduction was observed in the controls. This study is part of the continuing research to identify synergistic culture systems for treating toxic compounds from polluted environments.
2
Barash, Danny, Johannes Sikorski, Elizabeth B. Perry, Eviatar Nevo et Evgeny Nudler. « Adaptive Mutations In RNA-Based Regulatory Mechanisms : Computational and Experimental Investigations ». Israel Journal of Ecology and Evolution 52, no 3-4 (12 avril 2006) : 263–79. http://dx.doi.org/10.1560/ijee_52_3-4_263.
Texte intégralRésumé :
Recent discoveries of RNA-based regulatory mechanisms have prompted substantial interest in how they formed and the extent to which varying environmental conditions have influenced their evolution. One class of RNA-based regulatory mechanism that has been found in bacteria is the riboswitch, regulating the biosynthesis of certain vitamins by an RNA genetic control element that senses small molecules and responds with a structural change that affects transcription termination or translation initiation without the participation of proteins. By taking the thiamin pyrophosphate (TPP)-riboswitch in Bacillus subtilis as a model system, we wish to examine whether beneficial mutations may exist at the level of RNA that will cause an improvement in organism fitness. By computationally analyzing the difference in primary and secondary structure of the B. subtilis TPP-riboswitch collected from the xeric "African" south-facing slope (SFS) vs. the mesic, "European", north-facing slope (NFS) in "Evolution Canyon" III at Nahal Shaharut, southern Israel, we wish to experimentally study the environmental effect on transcription termination in these RNA-based regulatory mechanisms that are believed to be of ancient origin in the evolutionary time scale. Computational results, so far, indicate that specific mutations affect the riboswitch conformation by causing a global rearrangement. We would like to check whether such mutations could be adaptive mutations that may have a beneficial fitness effect, taking the TPP-riboswitch as a model system at the micro-scale. Empirical results so far indicate that in the promoter region of the TPP-riboswitch, all mutations increase nucleotide GC content in the xeric SFS, whereas in the mesic NFS they increase AT content. Preliminary examination of termination efficiency of strains found exclusively on one slope or the other, reveal increased termination efficiency in the presence of TPP and at more moderate temperatures, but only a suggestion of greater termination efficiency from strains found on both slopes. We expect that further results will shed light on the mutational differences of TPP-riboswitch sequences found on opposite slopes of "Evolution Canyon" III at Nahal Shaharut, potentially leading to interesting discoveries that relate to the topic of adaptive, nonrandom mutations.
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Shantaram, Manjula. « Bioterrorism ». Biomedicine 41, no 2 (2 juillet 2021) : 167. http://dx.doi.org/10.51248/.v41i2.776.
Texte intégralRésumé :
Terrorism that involves the deliberate release or distribution of biological agents is called bioterrorism. These pathogens are bacteria, viruses, fungi, other microorganisms and their related toxins, insects, and they can be natural or human-modified forms, which are roughly the same way as in biological warfare that can sicken or kill people, livestock, or crops.
These high-priority means include organisms or toxins that pose the greatest risk to the public and national security: Anthrax (Bacillus anthracis) Botulism (Clostridium botulinum toxin) Plague (Yersinia pestis). They have the ability to have harmful effects on human health in many ways, from relatively mild allergic reactions to serious medical conditions and even death. Bacillus anthracis, the bacterium that produces anthrax, and is one of the pathogens most likely to be used for biological attacks.Bioterrorism cancausemass deaths, epidemics, medical staff illness, environmental pollution, legal issues, and cause anxiety in the medical community and the wider community (1).
Unfortunately, bioterrorism agents are difficult to control and affect military personnel and civilian men, women and children. In the past 100 years, the United States and the international community have experienced various acts of bioterrorism against civilians. The model shows that the economic impact of bioterrorism attacks ranges from an estimated US$477.7 million per 100,000 people exposed (brucellosis scenario) to US$26.2 billion per 100,000 people exposed (anthrax scenario). The possibility of bioterrorism is particularly worrying because it causes disease, death and panic, disproportionate to the resources consumed (2).
The purpose of bioterrorism is usually to create fear and / or threaten the government or society in order to obtain political, religious or ideological objectives. Compared to weapons like explosives, it can have a unique impact on society. Depending on the situation, wear a mask to reduce inhalation or spread of bacteria. If you have been in contact with biological agents, remove and store your clothing and personal things. Follow official instructions for disposing of contaminated items. Wash with soap and water and put on clean clothes.
Bioterrorism agents can be spread through the air or into food or water, and are extremely difficult to detect. The outbreak of biological weapons’ diseases may lead to the extinction of endangered wild animal species, the erosion of genetic diversity of domesticated animals and plants, and the destruction of traditional human livelihoods (3). Symptoms of exposure to biological agents may include sore throat, fever, blurred vision or diplopia, rash or blistering, exhaustion, slurred speech, confusion, muscle weakness, nausea, abdominal pain, vomiting, diarrhoea, and cough. The occurrence of a weapon attack may be impossible, but planning and preparation can greatly reduce the death and suffering caused by it.
Only 16 countries plus Taiwan possess or presumably possess biological weapons programs: Canada, China, Cuba, France, Germany, Iran, Iraq, Israel, Japan, Libya, North Korea, Russia, South Africa, Syria, and the United States. Britain and the United States. The way to deal with such threats is through international law and carefully negotiated treaties and verification mechanisms. An important protection measure against biological weapons is currently being negotiated in Geneva. Available protective equipment includes respiratory protection devices, full-face protective masks and surgical masks for respiratory protection, combat suits, protective gloves, and skin-protecting boots. Full protection is required when the agent is not recognized. The inherent characteristics of biological agents that affect their potential for use as weapons include: virulence; toxicity; pathogenicity; incubation period; transmissibility; lethality and stability.
Now regarding the COVID19 pandemic, there is a game of blame between the two superpowers, the United States and China. It is not clear whether the spread of COVID19 is intentional or unintentional, whether it is a natural virus threatening the world or an artificial virus. Two conspiracy theories about the origin of COVID19 are widely circulated in China and the West, one accusing the United States and the other accusing the higher-level biological containment laboratory in Wuhan, the epicentre of the pandemic (4).
However, this has caused pain, death, mental distress, depression, and billions of dollars in treatment and vaccine costs all over the world. This whole process reminds us of Frankenstein's sci-fi monster. The moral lesson learned from this is that people need to blend in and feel connected to others in order to survive. In addition, humans must carefully consider the cost of scientific progress.
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Ugbenyen, Anthony M., John J. Simonis et Albertus K. Basson. « Screening for Bioflocculant-Producing Bacteria from the Marine Environment of Sodwana Bay, South Africa ». Annals of Science and Technology 3, no 1 (1 juin 2018) : 16–20. http://dx.doi.org/10.2478/ast-2018-0010.
Texte intégralRésumé :
AbstractFlocculants are chemicals that mediate flocculation process, by aggregating colloids from suspension to form floc. Chemical flocculants are hazardous to the environment, which inform the search for safer and eco-friendly alternatives from microorganisms. Bacterial strains were isolated from water and sediment samples collected from Sodwana Bay, South Africa, and physiological properties of the bacterial strains were observed. Flocculation test using kaolin clay suspension was done on all isolates and the ones that showed flocculating activity were identified molecularly using 16 rRNA gene sequence analysis. Forty marine bacteria isolates were gotten from sediments and water samples collected from Sodwana Bay. Most of the isolates exhibited a range of colony pigmentation (pink, creamy, yellow, and white). After purification of individual isolates, they were screened for their potential to produce bioflocculant. The result revealed that isolates marked SOD3, SOD10, SOD12, SOD26, SOD27, SOD28, SOD32, SOD33 and SOD34 produced bioflocculants as shown by the flocculating activities from their crude extract. All these isolates showed good flocculation of kaolin clay suspension above 60% (flocculating activity) except SOD12. These bioflocculant producing isolates were identified asPseudoalteromonas sp,Alcaligenes faecalis,Bacillus subtilis,Bacillus cereus,Bacillus stratosphericus. The results showed Sodwana Bay, South Africa as a reservoir of bacteria with potential to produce flocculants. However, further studies on the optimisation of culture conditions for bioflocculant production, extraction, characterisation and application of isolates is on the way to underscore the biotechnological importance of these microbes as producers of substitutes to harmful chemical flocculants commonly used in water and wastewater treatment.
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Morakinyo, Oyewale, Matlou Mokgobu, Murembiwa Mukhola et Tshifhiwa Godobedzha. « Biological Composition of Respirable Particulate Matter in an Industrial Vicinity in South Africa ». International Journal of Environmental Research and Public Health 16, no 4 (21 février 2019) : 629. http://dx.doi.org/10.3390/ijerph16040629.
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There is a growing concern that exposure to particulate matter of aerodynamic diameter of less than 2.5 µm (PM2.5) with biological composition (bioaerosols) may play a key role in the prevalence of adverse health outcomes in humans. This study determined the bacterial and fungal concentrations in PM2.5 and their inhalation health risks in an industrial vicinity in South Africa. Samples of PM2.5 collected on a 47-mm glass fiber filter during winter and summer months were analysed for bacterial and fungal content using standard methods. The health risks from inhalation of bioaerosols were done by estimating the age-specific dose rate. The concentration of bacteria (168–378 CFU/m3) was higher than fungi (58–155 CFU/m3). Bacterial and fungal concentrations in PM2.5 were lower in winter than in the summer season. Bacteria identified in summer were similar to those identified in winter: Staphylococcus sp., Bacillus sp., Micrococcus sp., Flavobacterium sp., Klebsiella sp. and Pseudomonas sp. Moreover, the fungal floras identified include Cladosporium spp., Aspergillus spp., Penicillium spp., Fusarium spp. and Alternaria spp. Children inhaled a higher dose of bacterial and fungal aerosols than adults. Bacteria and fungi are part of the bioaerosol components of PM2.5. Bioaerosol exposure may present additional health risks for children.
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Govender, Veloshinie, Lise Korsten et Dharini Sivakumar. « Semi-commercial evaluation of Bacillus licheniformis to control mango postharvest diseases in South Africa ». Postharvest Biology and Technology 38, no 1 (octobre 2005) : 57–65. http://dx.doi.org/10.1016/j.postharvbio.2005.04.005.
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Babalola, Olubukola Oluranti, Bartholomew Saanu Adeleke et Ayansina Segun Ayangbenro. « Whole Genome Sequencing of Sunflower Root-Associated Bacillus cereus ». Evolutionary Bioinformatics 17 (janvier 2021) : 117693432110389. http://dx.doi.org/10.1177/11769343211038948.
Texte intégralRésumé :
In recent times, diverse agriculturally important endophytic bacteria colonizing plant endosphere have been identified. Harnessing the potential of Bacillus species from sunflower could reveal their biotechnological and agricultural importance. Here, we present genomic insights into B. cereus T4S isolated from sunflower sourced from Lichtenburg, South Africa. Genome analysis revealed a sequence read count of 7 255 762, a genome size of 5 945 881 bp, and G + C content of 34.8%. The genome contains various protein-coding genes involved in various metabolic pathways. The detection of genes involved in the metabolism of organic substrates and chemotaxis could enhance plant-microbe interactions in the synthesis of biological products with biotechnological and agricultural importance.
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Carstens, Alewyn, Catheleen Bartie, Rainier Dennis et Carlos Bezuidenhout. « Antibiotic-resistant heterotrophic plate count bacteria and amoeba-resistant bacteria in aquifers of the Mooi River, North West province, South Africa ». Journal of Water and Health 12, no 4 (25 avril 2014) : 835–45. http://dx.doi.org/10.2166/wh.2014.226.
Texte intégralRésumé :
Groundwater in the Mooi River catchment is prone to mining, agricultural, municipal and septic tank pollution. In this study physico-chemical and microbiological parameters were determined using appropriate methods. Bacterial isolates were identified by 16S rRNA sequencing (heterotrophic plate count (HPC) bacteria and amoeba-resistant bacteria (ARB)) and multiplex polymerase chain reaction (Escherichia coli). Antibiotic resistance tests were also performed. Physico-chemical parameters were generally within target water quality ranges for drinking water. HPC bacteria ranged between 105 and 107 colony-forming units (cfu)/ml. E. coli were enumerated from Trimpark, School and Cemetery. The Blaauwbank borehole was negative for faecal streptococci. Pseudomonas spp. were most abundant in the bulk water. Opportunistic pathogens isolated included Pseudomonas aeruginosa, Acinetobacter, Aeromonas, Alcaligenes, Flavobacterium, Bacillus cereus and Mycobacterium spp. Varying patterns of antibiotic resistance were observed. Most HPC bacterial isolates were resistant to cephalothin and/or amoxicillin and a few were resistant to erythromycin and streptomycin. Pseudomonas spp. was also the most abundant ARB. Other ARBs included Alcaligenes faecalis, Ochrobactrum sp. and Achromobacter sp. ARBs were resistant to streptomycin, chloramphenicol, cephalothin, and/or amoxicillin compared to HPCs. The presence of E. coli and ARB in these groundwater sources indicates potential human health risks. These risks should be further investigated and quantified, and groundwater should be treated before use.
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Mardiah, Irma. « Identification of Endophytic Bacterial Isolated from Oil Palm Plants with Anti-Fungal Acitvity against Ganoderma boninense ». Pharmacology and Clinical Pharmacy Research 3, no 2 (31 août 2018) : 41. http://dx.doi.org/10.15416/pcpr.v3i2.20005.
Texte intégralRésumé :
Endophytic bacteria is an excellent candidates for the biological control of pathogenic fungi in plantations. The objectives of this study were to isolate and examine anti-fungal activity of endophytic bacteria from oil palm plantations in South Kalimantan against Ganoderma boninense. This research was performed in three phases, i.e., isolation, selection, and assessment of endophytic bacteria isolates against Ganoderma boninense. A total of 126 colonies of endophytic bacteria were isolated. The result of the anti-fungal activity test with dual culture method demostrated that BKA 10 isolate had the largest inhibition zone (62.22%). Molecular identification by DNA analysis using 16S rRNA primers showed that BKA 10 is most closely related to Bacillus cereus. In conclusion, isolate with the best anti-fungal acitivity against Ganoderma boninense has the closest kinship with Bacillus cereus. Keywords: antifungal, dual culture, Bacillus cereus.
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Molokwane, Pulane E., et Evans M. Nkhalambayausi-Chirwa. « Microbial culture dynamics and chromium (VI) removal in packed-column microcosm reactors ». Water Science and Technology 60, no 2 (1 juillet 2009) : 381–88. http://dx.doi.org/10.2166/wst.2009.349.
Texte intégralRésumé :
Microbial Cr(VI) reduction in groundwater aquifer media was investigated in microcosm reactors extracted from Cr(VI) contaminated sites in South Africa. The reactors were operated under an influent Cr(VI) concentration of 40 mg/L to simulate the current Cr(VI) level at the contaminated site. Near complete Cr(VI) removal was observed in microcosm reactors inoculated with Cr(VI) reducing bacteria from dried activated sludge collected from a treatment plant receiving periodic loadings of Cr(VI). The best performance was observed under low hydraulic loading (flow rate, Q=0.310 cm3/hr). Microbial culture characterisation results showed a change in culture composition after 17 days of reactor operation, indicating Bacillus and Lysinibacillus species as the most dominant organisms in reactors that reduced Cr(VI). The predominance of Bacillus and Lysinibacillus species was either due to resilience against toxicity or adaptation to the changing conditions in the reactor. This research was the initial step towards the development of an in situ bioremediation process to contain the spread of a Cr(VI) plume in a groundwater aquifer at contaminated site in Brits, South Africa. South Africa holds about 72% percent of the world’s chromium resources, the majority of which is mined in the North Eastern region of the country formally known as Transvaal.
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Luang-In, Vijitra, Manatchanok Yotchaisarn, Worachot Saengha, Piyachat Udomwong, Sirirat Deeseenthum et Kedsukon Maneewan. « Isolation and Identification of Amylase-producing Bacteria from Soil in Nasinuan Community Forest, Maha Sarakham, Thailand ». Biomedical & ; Pharmacology Journal 12, no 3 (18 août 2019) : 1061–68. http://dx.doi.org/10.13005/bpj/1735.
Texte intégralRésumé :
This study aimed to isolate and identify bacteria that can produce amylase enzyme from the unexplored Nasinuan Forest, Kantarawichai District, Mahasarakham Province, Thailand. Thirteen bacterial isolates with amylase-producing capacity on 1% starch agar were identified using 16S rRNA sequencing. Twelve bacteria were gram-positive, rod shaped and identified as Bacillus spp. and one bacterium with gram-negative and rod shaped character was Enterobacter cloacae. Their closest relatives were found in India, China, Korea, Indonesia, Argentina, Italy, Israel, USA, Argentina and South Africa. These bacteria were tested for specific amylase activity after 1-3 days enzyme induction with 1% starch at 37°C. The results showed the highest specific activity at day 2 incubation in the order: Bacillus cereus 3.5AL2 > 3.4AL1 > 1.4AL3 and thus 2-day enzyme induction was chosen for further analysis. Bacillus sp. 3.5AL2 was found to exhibit the highest specific amylase enzyme activity of 1.97 ± 0.41 U/mg protein at the optimal conditions of 60°C and pH 7.0 after 30 min incubation with 1% starch in 0.05 M PBS buffer. This amylase–producing bacterial strain offers great potential for applications in food and agricultural industries in Thailand.
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Muzhinji, N., J. W. Woodhall, M. Truter et J. E. van der Waals. « Variation in Fungicide Sensitivity AmongRhizoctoniaIsolates Recovered from Potatoes in South Africa ». Plant Disease 102, no 8 (août 2018) : 1520–26. http://dx.doi.org/10.1094/pdis-09-17-1470-re.
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Rhizoctonia is a major pathogen of potato causing substantial yield losses worldwide. Control of Rhizoctonia diseases is based predominantly on the application of fungicides. However, little is known about the fungicide response variability of different Rhizoctonia anastomosis groups associated with potato diseases in South Africa. A total of 131 Rhizoctonia isolates were obtained from potato growing regions of South Africa from 2012 to 2014 and evaluated for sensitivity to fungicides in vitro and in vivo. The fungicides comprised six chemical formulations and one bio-fungicide representing seven Fungicide Resistance Action Committee groups. All Rhizoctonia anastomosis groups were sensitive to tolclofos-methyl (EC50: 0.001 to 0.098 μg a.i. ml−1) and fludioxonil (EC50: 0.06 to 0.09 μg a.i. ml−1) and showed variation in sensitivity to pencycuron, iprodione, benomyl, and Bacillus subtilis QST 713. However, for azoxystrobin, Rhizoctonia isolates exhibited variable sensitivity ranging from sensitivity (EC50: <0.09 μg a.i. ml−1) to insensitivity with EC50values exceeding 5 μg a.i. ml−1. In greenhouse and field trials, tolclofos-methyl and fludioxonil exhibited significantly greater control of stem and black scurf whereas azoxystrobin was the least effective. This work demonstrated variable sensitivity within and among anastomosis groups of R. solani and binucleate Rhizoctonia to different fungicides. Information on fungicide sensitivity of Rhizoctonia isolates is crucial in the development of effective Rhizoctonia control strategies and facilitates monitoring of fungicide insensitive isolates in the pathogen population.
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Korsten, L., E. E. De Villiers, F. C. Wehner et J. M. Kotzé. « Field Sprays of Bacillus subtilis and Fungicides for Control of Preharvest Fruit Diseases of Avocado in South Africa ». Plant Disease 81, no 5 (mai 1997) : 455–59. http://dx.doi.org/10.1094/pdis.1997.81.5.455.
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In 3 consecutive years, preharvest applications of Bacillus subtilis field sprays integrated with copper oxychloride or benomyl consistently reduced severity of avocado black spot (BS), caused by Pseudocercospora purpurea at Omega, Republic of South Africa. Control was equal to that obtained with copper oxychloride or benomyl-copper oxychloride in the first and third years of spraying at Omega. In the second year, only the integrated treatment controlled BS, while copper oxychloride proved ineffective. The antagonist was applied on its own or integrated with copper oxychloride sprays at two other geographically distinct locations, Westfalia Estate and Waterval. The integrated and biological treatments at these localities were less effective than copper oxychloride sprays in controlling BS disease. Integrated control was more effective than B. subtilis sprays at Westfalia. On continuation of the biological spray program at Waterval for an additional three seasons, control was as effective as copper oxychloride in the last 2 years of spraying. Sooty blotch (SB), caused by an Akaropeltopsis sp., was reduced by the integrated treatment at Omega during the second season and at Westfalia during the first season. Although the two fungicide treatments reduced SB at Omega in the first season, copper oxychloride increased it above that of the control in the third season. Only the copper oxychloride treatment reduced SB at Waterval in the third season, while the B. subtilis treatment increased disease above that of the control in the fourth season.
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Jonathan Okokon Ekanem et Divine Jacob Ottong. « Microbiological analysis of Udo Anwankwo river in Ikot Ekpene, South-South Nigeria ». Open Access Research Journal of Science and Technology 1, no 2 (30 juin 2021) : 005–11. http://dx.doi.org/10.53022/oarjst.2021.1.2.0033.
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The microbiological study of water samples obtained from Udo Anwankwo River was investigated. Water samples were collected from three different sampling points along the course of the river and analyzed using standard procedures. The total bacterial counts, total coliform counts and total fungal counts of the water samples ranged from 2.6×105 to 4.8×105cfu/ml, 1.2×104 to 1.8×105cfu/ml and 0.24×103 to 1.9×103cfu/ml respectively. A total of nine bacteria species belonging to the following genera, Bacillus, Salmonella, Escherichia, Pseudomonas, Micrococcus, Staphylococcus, Vibrio, Enterobacter and Streptococcus were isolated and identified from the samples, while five fungal isolates including members of the genera Aspergillus niger, Mucor, Penicillum, Rhizopus and Fusarium were isolated. The study through microbial analysis has revealed that the river water sample was not free from pathogens and thereby not suitable for potable use. There is need to put adequate measures towards the control of pollution and proper treatment of the water before usage as it contains pathogenic organisms.
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Mashau, Mpho Edward, Lucy Lynn Maliwichi et Afam Israel Obiefuna Jideani. « Non-Alcoholic Fermentation of Maize (Zea mays) in Sub-Saharan Africa ». Fermentation 7, no 3 (18 août 2021) : 158. http://dx.doi.org/10.3390/fermentation7030158.
Texte intégralRésumé :
Maize, together with its fermented products, is fundamental for human nutrition and animal feed globally. Non-alcoholic fermentation of maize using lactic acid bacteria (LAB) is one of the food preservation methods that has been utilised throughout the centuries and has played a vital role in the manufacturing of many fermented beverages consumed these days. However, the coincidence of LAB and yeasts during the spontaneous fermentation of maize-based products is inevitable. The involvement of other microorganisms such as moulds, Bacillus species and acetic acid bacteria in the fermentation of maize is important to the characteristics of the final product. Fermented beverages are affordable, have been produced traditionally and are known for their organoleptic properties, as well as their health-promoting compounds. The consumption of non-alcoholic beverages has the prospect of reducing the detrimental health and economic effects of a poor diet. Different fermented maize-based gruels and beverages such as ogi, mawe, banku and kenkey in West Africa, togwa in East Africa, as well as mahewu in South Africa have been documented. The physical and biochemical properties of most of these maize-based fermented products have been investigated and modified by various researchers. Attempts to enhance the nutritional properties of these products rely on supplementation with legumes to supply the insufficient amino acids. The production technology of these products has evolved from traditional to industrial production in recent years.
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Higashi, Hideaki, et Hiroshi Kida. « Research Activities of Hokudai Center for Zoonosis Control in Zambia ». Journal of Disaster Research 9, no 5 (1 octobre 2014) : 818–22. http://dx.doi.org/10.20965/jdr.2014.p0818.
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The Hokkaido University Research Center for Zoonosis Control (CZC) established the Hokudai Center for Zoonosis Control in Zambia (HUCZCZ) at the School of Veterinary Medicine, the University of Zambia, in 2007 to control zoonotic diseases in the areas of South Africa, where various emerging infectious diseases have occurred. The CZC promotes epidemiological studies and basic researches of infectious diseases caused by viruses, protozoa, and bacteria by using the biosafety level 3 facility in the HUCZCZ. This article introduces research activities of the HUCZCZ in Zambia.
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Han, Khin SL, Lopez Gustavo, Venesh C. Rajkumar et Khine Swe Swe-Han. « Antimicrobial stewardship approach : Prevalence of antimicrobial resistant bacteria at a regional hospital in South Africa ». Journal of Infection in Developing Countries 13, no 08 (31 août 2019) : 748–52. http://dx.doi.org/10.3855/jidc.10685.
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Introduction: Antimicrobial stewardship practices are crucial for the regular surveillance to change the antimicrobial policy. This study was conducted to decide the prevalence of common bacteria and their antibiogram regarding antimicrobial stewardship program within one year, at the regional and district, Stanger hospital in South Africa.
Methodology: It was based the study on clinical data and laboratory records of the patients. It reviewed the clinical and laboratory data. The prevalence/proportion rate was calculated and correlated with the majority of microorganism vs empirical therapy.
Results: The prevalence of MRSA, MRSE, VRSA, ESBL+ K. pneumoniae; E. coli cultured from the blood was 25%, 49%, 2%, 62% and 27% respectively. Similarly, we analysed for other targeted MDROs organisms (Acinetobacter species and P. aeruginosa, CRE, CPE) isolated from blood culture and endotracheal aspirate. The prevalence of MDR Acinetobacter species exceeded 61%, 33% from the blood and ETA respectively. The prevalence of MDR P. aeruginosa was 10% from ETA. The MRSA, MRSE, VRSA, VRE were observed in blood specimen. The majority of the microorganisms cultured from the CSF was Cryptococcus neoformans and followed by bacteria: Streptococcus pneumonia, Streptococcus group B and Haemorphilus influenza.
Conclusion: The selection of empirical antimicrobial therapy relates not only the institutions or unit-specific antibiogram but also the site of infection. We can further suggest continuing to do surveillance of antibiogram and prevalence of MDR organisms for infection control as well as for empirical therapy, part of the antimicrobial stewardship program based on yearly records to change the local hospital antibiotic policy.
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Ugbenyen, A. M., N. Vine, J. J. Simonis, A. K. Basson et A. I. Okoh. « Characterization of a bioflocculant produced from the consortium of three marine bacteria of the genera Cobetia and Bacillus and its application for wastewater treatment ». Journal of Water, Sanitation and Hygiene for Development 5, no 1 (17 novembre 2014) : 81–88. http://dx.doi.org/10.2166/washdev.2014.181.
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In this study, we purified and characterized bioflocculant from a mixed culture of three marine bacteria (Cobetia sp. OAUIFE, Bacillus sp. MAYA, and Bacillus sp. Gilbert with accession number JF799092, JF799093, and HQ537128, respectively) isolated from the sediment sample of Algoa Bay South Africa. The bioflocculant from the consortium showed high flocculation of river water, brewery wastewater, and dairy wastewater, with resultant flocculating activities of 96.4%, 93.7%, and 82.2%, respectively. The applicability of the bioflocculant for removing turbidity and reducing chemical oxygen demand (COD) from these real wastewaters was excellent. The bioflocculant turbidity removal efficiency for brewery wastewater was 92%, while its COD reduction efficiency for dairy wastewater was 99%. A scanning electron microscopy (SEM) image of the purified bioflocculant revealed an amorphous morphology, while Fourier transform infra-red (FTIR) analysis also revealed the presence of amino, hydroxyl, and carboxyl functional groups among others, which could be responsible for the high-flocculating activity of the bioflocculant. This environmental-friendly bioflocculant holds promise for application in the field of biotechnology.
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de Jager, Pieter, Tobias Chirwa, Shan Naidoo, Olga Perovic et Juno Thomas. « Nosocomial Outbreak of New Delhi Metallo-β-Lactamase-1-Producing Gram-Negative Bacteria in South Africa : A Case-Control Study ». PLOS ONE 10, no 4 (24 avril 2015) : e0123337. http://dx.doi.org/10.1371/journal.pone.0123337.
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Molokwane, P. E., C. K. Meli et E. M. N. Chirwa. « Chromium (VI) reduction in activated sludge bacteria exposed to high chromium loading ». Water Science and Technology 58, no 2 (1 août 2008) : 399–405. http://dx.doi.org/10.2166/wst.2008.669.
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A mixed-culture of bacteria collected from a wastewater treatment plant in Brits, North-West Province (South Africa) biocatalytically reduced Cr(VI) at much higher concentrations than previously observed in cultures isolated in North America. Complete Cr(VI) reduction in aerobic cultures was achieved at a high concentration of 200 mg/L after incubation for only 65 hours. Under anaerobic conditions up to 150 mg, Cr(VI)/L was completely removed after incubating for 130 to 155 hours, still higher than the Cr(VI) reduction achieved with previous cultures where complete removal was only observed in cultures with the added Cr(VI) concentration not greater than 30 mg/L. Cr(VI) reduction capability of the cultures was verified in purified cultures. Consortium cultures were characterised using 16S rRNA partial sequence analysis. Results showed that the gram-positive Bacillus genera predominated under aerobic conditions with a small composition of the gram-negative Microbacterium sp. There was more biodiversity observed in the anaerobic cultures with the marked appearance of Enterococcus, Arthrobacter, Paenibacillus and Oceanobacillus species. The results showed that Cr(VI) reduction rate in the new culture was up to eight times higher than that previously observed in other Cr(VI) reducing cultures isolated from Cr(VI) contaminated soil environments in Newark (New Jersey) and other sites in North America.
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Abebe, Lydia Shawel, James A. Smith, Sophia Narkiewicz, Vinka Oyanedel-Craver, Mark Conaway, Alukhethi Singo, Samie Amidou, Paul Mojapelo, Julia Brant et Rebecca Dillingham. « Ceramic water filters impregnated with silver nanoparticles as a point-of-use water-treatment intervention for HIV-positive individuals in Limpopo Province, South Africa : a pilot study of technological performance and human health benefits ». Journal of Water and Health 12, no 2 (6 septembre 2013) : 288–300. http://dx.doi.org/10.2166/wh.2013.185.
Texte intégralRésumé :
Waterborne pathogens present a significant threat to people living with the human immunodeficiency virus (PLWH). This study presents a randomized, controlled trial that evaluates whether a household-level ceramic water filter (CWF) intervention can improve drinking water quality and decrease days of diarrhea in PLWH in rural South Africa. Seventy-four participants were randomized in an intervention group with CWFs and a control group without filters. Participants in the CWF arm received CWFs impregnated with silver nanoparticles and associated safe-storage containers. Water and stool samples were collected at baseline and 12 months. Diarrhea incidence was self-reported weekly for 12 months. The average diarrhea rate in the control group was 0.064 days/week compared to 0.015 days/week in the intervention group (p < 0.001, Mann–Whitney). Median reduction of total coliform bacteria was 100% at enrollment and final collection. CWFs are an acceptable technology that can significantly improve the quality of household water and decrease days of diarrhea for PLWH in rural South Africa.
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Neelakantan, Vivek. « Tuberculosis control in postcolonial South India and beyond : Fractured sovereignties in international health, 1948-1960 ». Wellcome Open Research 2 (13 janvier 2017) : 4. http://dx.doi.org/10.12688/wellcomeopenres.10544.1.
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Between 1948 and 1960, South India (Madras State) and Southeast Asia emerged as global centres for tuberculosis control. This article attempts to situate tuberculosis control of these two regions within the broader context of international health. It investigates the unique ways in which tuberculosis control in Madras state reflected the inner tensions between the notional magic bullet approach, which focuses on specific cures to root out the cause of the disease, and a more holistic approach that relates disease prevention to overall well-being of the population. The implementation of tuberculosis control across South India and Southeast Asia shed light on the nature of the post-colonial state sovereignty in public health. Across India, as in Southeast Asia, the state sovereignty appertaining to the implementation of health policy was fractured, as evident in the opposition to the Bacillus Calmette– Guérin (BCG) vaccination. Based on a wide range of archival materials, this article examines tuberculosis control in South India and Southeast Asia between 1948 and 1960. It situates tuberculosis control within the context of nationalist discourse and preventive medicine. In doing so, it adds not only to the historiography of tuberculosis in non-Western contexts, which has hitherto focused on India, Sri Lanka, Africa, or the Caribbean, but also to the relatively new field of Southeast Asian medical history.
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Neelakantan, Vivek. « Tuberculosis control in postcolonial South India and Southeast Asia : Fractured sovereignties in international health, 1948-1960 ». Wellcome Open Research 2 (17 avril 2018) : 4. http://dx.doi.org/10.12688/wellcomeopenres.10544.2.
Texte intégralRésumé :
Between 1948 and 1960, South India (Madras State) and Southeast Asia—with an emphasis on Indonesia, the Philippines, and Burma— emerged as global centres for tuberculosis control. This article attempts to situate tuberculosis control of these two regions within the broader context of transnational health. It investigates the unique ways in which tuberculosis control in South India and Southeast Asia reflected the inner tensions between the notional magic bullet approach, which focuses on specific cures to root out the cause of the disease, and a more holistic approach that relates disease prevention to overall well-being of the population. The implementation of tuberculosis control programs across South India and Southeast Asia shed light on the nature of the postcolonial state sovereignty in public health. Across India, as in Southeast Asia, the state sovereignty appertaining to the implementation of health policy was fractured, as evident in the opposition to the Bacillus Calmette–Guérin (BCG) vaccination. Based on a wide range of archival materials, this article situates tuberculosis control within the context of nationalist discourse and preventive medicine. In doing so, it adds not only to the historiography of tuberculosis in non-Western contexts, which has hitherto focused on India, Sri Lanka, or Africa but also to the relatively new field of Southeast Asian medical history.
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du PLESSIS, ERIKA M., FRANCOIS DUVENAGE et LISE KORSTEN. « Determining the Potential Link between Irrigation Water Quality and the Microbiological Quality of Onions by Phenotypic and Genotypic Characterization of Escherichia coli Isolates ». Journal of Food Protection 78, no 4 (1 avril 2015) : 643–51. http://dx.doi.org/10.4315/0362-028x.jfp-14-486.
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The potential transfer of human pathogenic bacteria present in irrigation water onto fresh produce was investigated, because surface water sources used for irrigation purposes in South Africa have increasingly been reported to be contaminated with enteric bacterial pathogens. A microbiological analysis was performed of a selected river in Limpopo Province, South Africa, that is often contaminated with raw sewage from municipal sewage works and overhead irrigated onions produced on a commercial farm. Counts of Escherichia coli, coliforms, aerobic bacteria, fungi, and yeasts and the prevalence of E. coli O157:H7, Salmonella, and Listeria monocytogenes were determined. Identities of bacterial isolates from irrigation water and onions were confirmed using matrix-assisted laser desorption ionization–time of flight mass spectrometry, PCR, and biochemical tests. To establish a potential link between the microbiological quality of the irrigation source and the onions, the E. coli isolates from both were subjected to antibiotic resistance, virulence gene, and enterobacterial repetitive intergenic consensus PCR analyses. River water E. coli counts exceeded South African Department of Water Affairs and World Health Organization irrigation water guidelines. Counts of aerobic bacteria, coliforms, fungi, and yeasts of onions from the market were acceptable according to Department of Health Directorate, Food Control, South Africa, microbiological guidelines for ready-to-eat fresh fruits and vegetables. E. coli O157:H7, Salmonella, and L. monocytogenes were not detected in onions, whereas only Salmonella was detected in 22% of water samples. Matrix-assisted laser desorption ionization–time of flight mass spectrometry and PCR identification of E. coli isolates from water and onions correlated. Of the 45 E. coli isolates from water and onions, 42.2% were resistant to multiple antibiotics. Virulence genes eae, stx1, and stx2 were detected in 2.2, 6.6, and 2.2% of the E. coli isolates, respectively. Phenotypic (antimicrobial) and genotypic (virulence gene prevalence, DNA fingerprinting) analyses showed a link between river, dam, irrigation pivot point, and onion E. coli isolates.
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Madoroba, Evelyn, Kudakwashe Magwedere, Nyaradzo Stella Chaora, Itumeleng Matle, Farai Muchadeyi, Masenyabu Aletta Mathole et Rian Pierneef. « Microbial Communities of Meat and Meat Products : An Exploratory Analysis of the Product Quality and Safety at Selected Enterprises in South Africa ». Microorganisms 9, no 3 (27 février 2021) : 507. http://dx.doi.org/10.3390/microorganisms9030507.
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Consumption of food that is contaminated by microorganisms, chemicals, and toxins may lead to significant morbidity and mortality, which has negative socioeconomic and public health implications. Monitoring and surveillance of microbial diversity along the food value chain is a key component for hazard identification and evaluation of potential pathogen risks from farm to the consumer. The aim of this study was to determine the microbial diversity in meat and meat products from different enterprises and meat types in South Africa. Samples (n = 2017) were analyzed for Yersinia enterocolitica, Salmonella species, Listeria monocytogenes, Campylobacter jejuni, Campylobacter coli, Staphylococcus aureus, Clostridium perfringens, Bacillus cereus, and Clostridium botulinum using culture-based methods. PCR was used for confirmation of selected pathogens. Of the 2017 samples analyzed, microbial ecology was assessed for selected subsamples where next generation sequencing had been conducted, followed by the application of computational methods to reconstruct individual genomes from the respective sample (metagenomics). With the exception of Clostridium botulinum, selective culture-dependent methods revealed that samples were contaminated with at least one of the tested foodborne pathogens. The data from metagenomics analysis revealed the presence of diverse bacteria, viruses, and fungi. The analyses provide evidence of diverse and highly variable microbial communities in products of animal origin, which is important for food safety, food labeling, biosecurity, and shelf life limiting spoilage by microorganisms.
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Dara, Surendra K., Cristian Montalva et Marek Barta. « Microbial Control of Invasive Forest Pests with Entomopathogenic Fungi : A Review of the Current Situation ». Insects 10, no 10 (12 octobre 2019) : 341. http://dx.doi.org/10.3390/insects10100341.
Texte intégralRésumé :
The health of the forestlands of the world is impacted by a number of insect pests and some of them cause significant damage with serious economic and environmental implications. Whether it is damage of the North American cypress aphid in South America and Africa, or the destruction of maple trees in North America by the Asian long horned beetle, invasive forest pests are a major problem in many parts of the world. Several studies explored microbial control opportunities of invasive forest pests with entomopathogenic bacteria, fungi, and viruses, and some are successfully utilized as a part of integrated forest pest management programs around the world. This manuscript discusses some invasive pests and the status of their microbial control around the world with entomopathogenic fungi.
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Essiet, Grace Akanimo, Monday Udofa Anwankwo, Godwin Christian Akuodor, Gloria Ahunna Ajoku, Casimir Chijioke Offor, Anthony Uchenna Megwas et Daniel Ogbonna John Aja. « Antibacterial and toxicological evaluation of the ethanol leaf extract of Anthonotha macrophylla ». Journal of Herbmed Pharmacology 8, no 3 (9 mai 2019) : 205–11. http://dx.doi.org/10.15171/jhp.2019.30.
Texte intégralRésumé :
Introduction: The leaves of Anthonotha macrophylla which are widely used in folkloric medicine in Africa were evaluated for antibacterial activity and its toxicological profile.Methods: Antibacterial activities of the leaves against clinical strains of Staphylococcus aureus, Escherichia coli, Salmonella typhi, Klebsiella pneumonia, Streptococcus pyogenes and Bacillus subtilis were compared with cefoxitin. Toxicological profiles were determined following the administration of 100, 200 and 400 mg/kg of the leaf extract and distilled water, as control, to male Albino rats for 28 days. Biochemical and hematological indices and body weights were determined and the vital organs were examined.Results: The ethanol leaf extract of A. macrophylla demonstrated antibacterial activity against the pathogenic bacteria tested. Toxicological investigation of the leaf extract showed no significant alterations in hematological and biochemical indices, and the vital organs as well. The LD50 in rats was more than 5000 mg/kg.Conclusion: Findings suggest that the ethanol leaf extract of A. macrophylla possess good antimicrobial activity which supports the traditional use of this plant across Africa. The plant is also considered safe following oral exposure after 28 days.
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Toews, Sheila, Mary Beverley-Burton et Tara Lawrimore. « Helminth and protist parasites of zebra mussels, Dreissena polymorpha (Pallas, 1771), in the Great Lakes region of southwestern Ontario, with comments on associated bacteria ». Canadian Journal of Zoology 71, no 9 (1 septembre 1993) : 1763–66. http://dx.doi.org/10.1139/z93-250.
Texte intégralRésumé :
Zebra mussels (Dreissena polymorpha) collected in June 1991 from three localities in the Great Lakes region of south-western Ontario were examined for helminth and protist parasites. In addition, the bacteria in both live and dead mussels were identified and the effects of Serratia liquefaciens and Escherichia coli on D. polymorpha were monitored experimentally. Helminths were not found in mussels from the Puce site (Lake St. Clair); the prevalence of plagiorchiid metacercariae in mussels from Port Colborne (Lake Erie) was 2.9% and of aspidogastrids (adults and juveniles of Aspidogaster conchicola) in mussels from Leamington (Lake Erie), 2.7%. These findings represent locality records and a new host record for the digenean. The ciliate Ophryoglena sp. was found in mussels from Puce (prevalence 1.3%), Port Colborne (prevalence 4.3%), and Leamington (prevalence 2.7%). The principal bacteria found in both living and dead mussels were Aeromonas sp., Pseudomonas sp., and Bacillus sp. Both high and low concentrations of S. liquefaciens that were tested were lethal to mussels, while similar concentrations of E. coli produced no effects. Both bacteria are recognized as being opportunistic pathogens in many organisms. These preliminary findings suggest that helminths will not play a major role in the control of zebra mussels. However, the potentially pathogenic ciliate protists and bacteria warrant further investigation.
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Ndibe, Thankgod Ositadinma, Nancy Erika Nwabufo, Johnson John Usman et Winnie Chuno Eugene. « Assessment of Some Bacteria from Panteka Stream, Kaduna, Nigeria, for their Larvicidal Activity Against Anopheles gambiae ». European Journal of Engineering Research and Science 3, no 12 (1 janvier 2019) : 149–54. http://dx.doi.org/10.24018/ejers.2018.3.12.1025.
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It is obvious that malaria is one of the commonest diseases in Africa, hence the need to embark on a study to reduce its transmission by eliminating the vector. Some microorganisms are known to have larvicidal activity leading to destruction of mosquito larvae, thereby, preventing them from metamorphosing into adult mosquitoes that can transmit Plasmodium spp. Panteka stream, Kaduna, Nigeria, is a dumping site for refuse and automobile waste and thus, a potential source of bacteria. This present investigation was aimed at screening bacterial isolates for their larvicidal activity against Anopheles gambiae. Standard methods were employed in sample collection, isolation, morphological, biochemical identification and protein profiling of these bacteria isolates. Five different types of bacteria were identified; Bacillus thuringiensis, Staphylococcus aureus, Micrococcus sedentarius, Enterococcus faecalis and Streptococcus pneumonia. Among these bacteria, B. thuringiensis exhibited the most larvicidal activity, followed by M. sedentarius. On the basis of lethal concentration (LC50), B. thuringiensis exhibited the highest lethal activity against Anopheles gambiae larvae at 48 hour duration of exposure. Results showed that concentration of bacterial isolates and duration of exposure of larvae to the bacterial isolates, determine the mortality rate of larvae. Sodium Dodecyl Sulphate Polyacrylamide Gel Electrophoresis (SDS-PAGE) revealed variable bands between B. thuringiensis and M. sedentarius, which might have accounted for their differences in larvicidal activity. The use of bacteria for the control of mosquito larvae is highly recommended. Further research should be conducted to search for more bacteria and possibly fungi which have potentials for larvicidal activity.
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Addae, Prince C., Mohammad F. Ishiyaku, Jean-Batiste Tignegre, Malick N. Ba, Joseph B. Bationo, Ibrahim D. K. Atokple, Mumuni Abudulai et al. « Efficacy of a cry1Ab Gene for Control of Maruca vitrata (Lepidoptera : Crambidae) in Cowpea (Fabales : Fabaceae) ». Journal of Economic Entomology 113, no 2 (22 janvier 2020) : 974–79. http://dx.doi.org/10.1093/jee/toz367.
Texte intégralRésumé :
Abstract Cowpea [Vigna unguiculata (L) Walp.] is an important staple legume in the diet of many households in sub-Saharan Africa. Its production, however, is negatively impacted by many insect pests including bean pod borer, Maruca vitrata F., which can cause 20–80% yield loss. Several genetically engineered cowpea events that contain a cry1Ab gene from Bacillus thuringiensis (Bt) for resistance against M. vitrata were evaluated in Nigeria, Burkina Faso, and Ghana (West Africa), where cowpea is commonly grown. As part of the regulatory safety package, these efficacy data were developed and evaluated by in-country scientists. The Bt-cowpea lines were planted in confined field trials under Insect-proof netting and artificially infested with up to 500 M. vitrata larvae per plant during bud formation and flowering periods. Bt-cowpea lines provided nearly complete pod and seed protection and in most cases resulted in significantly increased seed yield over non-Bt control lines. An integrated pest management strategy that includes use of Bt-cowpea augmented with minimal insecticide treatment for protection against other insects is recommended to control pod borer to enhance cowpea production. The insect resistance management plan is based on the high-dose refuge strategy where non-Bt-cowpea and natural refuges are expected to provide M. vitrata susceptible to Cry1Ab protein. In addition, there will be a limited release of this product until a two-toxin cowpea pyramid is released. Other than South African genetically engineered crops, Bt-cowpea is the first genetically engineered food crop developed by the public sector and approved for release in sub-Saharan Africa.
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Pavlov, D., C. M. E. de Wet, W. O. K. Grabow et M. M. Ehlers. « Determination of cytotoxicity and invasiveness of heterotrophic plate count bacteria isolated from drinking water ». Water Supply 2, no 3 (1 juillet 2002) : 115–22. http://dx.doi.org/10.2166/ws.2002.0093.
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Evidence has been presented that some heterotrophic bacteria often detected in drinking water supplies possess features associated with pathogenicity. This suggests that even the low numbers of heterotrophic bacteria considered acceptable by drinking water specifications may constitute a health risk, particularly to immunocompromised consumers. In this study, 339 bacteria were isolated at random from routine heterotrophic plate count (HPC) tests on selected drinking water supplies in South Africa. In a first screen for potentially pathogenic properties, 188 of the isolates (55.5%) displayed a- or b-haemolysis on blood agar. Further analysis of the haemolytic isolates for enzymes associated with virulence revealed the presence of chondroitinase (5.3%), coagulase (16.0%), DNase (60.6%), elastase (33.0%), fibrinolysin (53.7%), gelatinase (62.2%), hyaluronidase (21.3%), lecithinase (47.9%), lipase (54.8%) and proteinase (64.4%) of the isolates. No fluorescein or pyocyanin was detected in any of the isolates. Among the haemolytic isolates 68.6% were resistant to oxacillin (1 μg), 59.6% to penicillin G (2 units), 47.3% to penicillin G (10 units), 53.7% to ampicillin (10 μg) and 42.6% to ampicillin (25 μg). Cytotoxicity, invasiveness and adherence properties of the haemolytic isolates was determined on HEp-2 and Caco2 cell lines. Among the haemolytic isolates 96% were cytolytic on the HEp-2 cell line. All the haemolytic isolates adhered to HEp-2 and Caco2 cells but gram-negative isolates tended to adhere in larger numbers than gram-positive isolates. HEp-2 cells were invaded by 42% of the haemolytic isolates. Heterotrophic bacteria, which most frequently revealed the above features associated with pathogenicity included species of the following genera: Aeromonas, Acinetobacter, Aureobacterium, Bacillus, Klebsiella, Moraxella, Pseudomonas, Staphylococcus, Tsukamurella and Vibrio. The results obtained in this study support earlier indications that bacteria detected by routine heterotrophic plate counts on drinking water supplies may include bacteria associated with potentially pathogenic properties. The extent to which these bacteria in drinking water supplies may constitute a health risk remains to be investigated.
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Sindi, Abrar, Md Bahadur Badsha, Barbara Nielsen et Gülhan Ünlü. « Antimicrobial Activity of Six International Artisanal Kefirs against Bacillus cereus, Listeria monocytogenes, Salmonella enterica Serovar Enteritidis, and Staphylococcus aureus ». Microorganisms 8, no 6 (4 juin 2020) : 849. http://dx.doi.org/10.3390/microorganisms8060849.
Texte intégralRésumé :
Kefir, a fermented dairy beverage, exhibits antimicrobial activity due to many metabolic products, including bacteriocins, generated by lactic acid bacteria. In this study, the antimicrobial activities of artisanal kefir products from Fusion Tea (A), Britain (B), Ireland (I), Lithuania (L), the Caucuses region (C), and South Korea (K) were investigated against select foodborne pathogens. Listeria monocytogenes CWD 1198, Salmonella enterica serovar Enteritidis ATCC 13076, Staphylococcus aureus ATCC 25923, and Bacillus cereus ATCC 14579 were inhibited by artisanal kefirs made with kefir grains from diverse origins. Kefirs A, B, and I inhibited all bacterial indicator strains examined at varying levels, except Escherichia coli ATCC 12435 (non-pathogenic, negative control). Kefirs K, L, and C inhibited all indicator strains, except S. aureus ATCC 25923 and E. coli ATCC 12435. Bacteriocins present in artisanal kefirs were determined to be the main antimicrobials in all kefirs examined. Kefir-based antimicrobials are being proposed as promising natural biopreservatives as per the results of the study.
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Rivers-Moore, N. A., S. Bangay et R. W. Palmer. « Optimisation of Bacillus thuringiensis var. israelensis (Vectobac®) applications for the blackfly control programme on the Orange River, South Africa ». Water SA 34, no 2 (19 février 2019) : 193. http://dx.doi.org/10.4314/wsa.v34i2.183639.
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McLeod, A., et S. Coertze. « First Report of Phytophthora cryptogea on Osteospermum spp. in South Africa ». Plant Disease 91, no 3 (mars 2007) : 322. http://dx.doi.org/10.1094/pdis-91-3-0322a.
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Osteospermum is the largest genus of the tribe Calendulea of the Compositae (Asteraceae) and has a center of diversity in South Africa with approximately 40 known species in the Cape Province (3). This indigenous plant genus is also a popular floricultural crop grown in South Africa because of drought and high temperature tolerance. Two diseased Osteospermum sp. samples were submitted by commercial nurseries to the Stellenbosch University Plant Disease Clinic. Both samples showed similar symptoms including black lesions on the lower stem, petioles, and the base of lower leaves. Isolations were made from roots, stems, and petioles following surface disinfestation of the lesions and plating on potato dextrose agar (PDA), water agar, PARP, and PARPH (1). The only microorganism that was consistently isolated from all lesions was a species of Phytophthora, from which single hyphal tip cultures were prepared. The cultures were identified morphologically as Phytophthora cryptogea Pethybridge & Lafferty. Morphological characteristics and cardinal growth temperatures followed Lévesque and de Cock (2). Distinctive morphological characteristics included abundant hyphal swellings in sterile soil extract and hemp seed water cultures, nonpapil-lated, persistent, internally proliferating, obpyriform sporangia having mean dimensions of 36 × 26 μm and mean length/breadth ratios that ranged from 1.30 to 1.53 (1). Cultures had a petaloid pattern on PDA and no growth at 35°C that distinguished it from Phytophthora drechsleri (1). Analyses and comparison of the internal transcribed spacer (ITS) regions of isolate STE-U 6133 (GenBank Accession No. GI DQ479410) supported the P. cryptogea identification. STE-U 6133 has been deposited in the Stellenbosch University culture collection. Pathogenicity of isolate STE-U 6133 was tested on six plants of Osteospermum jucundum (Phill.) T. Norl. and O. ecklonis (DC.) Norl. in individual containers. Inoculum was grown on V8 agar for 7 days, and 10-mm culture disks were incubated in a filter (0.2 μm) sterilized 1% soil extract solution (1). The disks were vortexed vigorously and filtered through miracloth (Calbiochem Corp., La Jolla, CA) to remove agar disks and excess mycelium. The inoculum concentration was adjusted to 104 sporangia/ml and incubated at 4°C for 4 h. Six plants were inoculated with a 10-ml suspension of sporangia and zoospores by pipetting the suspension at the collar of each plant. Another six plants were treated with water as controls. The inoculated plants were kept at temperatures ranging from 22 to 25°C and were watered until saturation every second day. Initial symptoms were black lesions on the lower stem and petiole bases developing 14 to 18 days after inoculation, followed by wilting of some plants. Control plants remained healthy. Isolations from symptomatic plants yielded only P. cryptogea of which pure cultures were established, completing Koch's postulate. The experiment was repeated with similar results. To our knowledge, this is the first report of P. cryptogea as a pathogen of O. jucundum and O. ecklonis in South Africa. P. cryptogea has been reported as a pathogen on Osteospermum spp. in other countries (4). References: (1) D. C. Erwin et al. Phytophthora Diseases Worldwide. The American Phytopathological Society. St. Paul, MN, 1996. (2) C. A. Lévesque and A. W. A. M. de Cock. Stud. Mycol. 50:481, 2004. (3) B. Nordenstam. Edinb. J. Bot. 60:259, 2003. (4) D. J. Stamps. Phytophthora cryptogea. IMI Description of Fungi and Bacteria. No. 60:Sheet 592. CAB International, Wallingford, UK, 1978.
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Sineke, Ncomeka, Jonathan Asante, Daniel Gyamfi Amoako, Akebe Luther King Abia, Keith Perrett, Linda A. Bester et Sabiha Y. Essack. « Staphylococcus aureus in Intensive Pig Production in South Africa : Antibiotic Resistance, Virulence Determinants, and Clonality ». Pathogens 10, no 3 (8 mars 2021) : 317. http://dx.doi.org/10.3390/pathogens10030317.
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Although Staphylococcus aureus is a major threat to the veterinary, agricultural, and public health sectors because of its zoonotic potential, studies on its molecular characterisation in intensive animal production are rare. We phenotypically and genotypically characterised antibiotic-resistant S. aureus in intensive pig production in South Africa, using the farm-to-fork approach. Samples (n = 461) were collected from the farm, transport vehicles, and the abattoir using the World Health Organisation on Integrated Surveillance of Antimicrobial Resistance (WHO-AGISAR) sampling protocol. Bacteria were isolated using selective media and identified using biochemical tests and polymerase chain reaction (PCR). Phenotypic resistance was determined using the disk diffusion method. Selected resistance and virulence genes were investigated using PCR. Clonality among the isolates was determined using the repetitive element sequence-PCR. In all, 333 presumptive staphylococcal isolates were obtained, with 141/333 (42.3%) identified as staphylococci biochemically. Ninety-seven (97; 68.8%) were confirmed as S. aureus using PCR, 52.6% of which were identified as methicillin-resistant S. aureus (MRSA) through the mecA gene. All the 97 S. aureus isolates (100%) were resistant to at least one of the antibiotics tested, with the highest resistance observed against erythromycin and clindamycin (84.50% each), and the lowest observed against amikacin (2.10%); 82.47% (80/97) were multidrug-resistant with an average multiple antibiotic resistance index of 0.50. Most of the phenotypically resistant isolates carried at least one of the corresponding resistance genes tested, ermC being the most detected. hla was the most detected virulence gene (38.14%) and etb was the least (1.03%). Genetic fingerprinting revealed diverse MRSA isolates along the farm-to-fork continuum, the major REP types consisting of isolates from different sources suggesting a potential transmission along the continuum. Resistance to antibiotics used as growth promoters was evidenced by the high prevalence of MDR isolates with elevated multiple antibiotic resistance indices >0.2, specifically at the farm, indicating exposure to high antibiotic use environments, necessitating antibiotic stewardship and proper infection control measures in pig husbandry and intensive pig production.
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CHRISTISON, C. A., D. LINDSAY et A. von HOLY. « Cleaning and Handling Implements as Potential Reservoirs for Bacterial Contamination of Some Ready-to-Eat Foods in Retail Delicatessen Environments ». Journal of Food Protection 70, no 12 (1 décembre 2007) : 2878–83. http://dx.doi.org/10.4315/0362-028x-70.12.2878.
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This study assessed the association of bacteria with cleaning tools, such as floor mops (n = 25) and cleaning cloths (n = 39), and handling devices, such as disposable plastic gloves (n = 20), used during filled baguette and assorted salad preparation in four selected retail delicatessens in Johannesburg, South Africa. Samples of each cleaning or handling tool were prepared for aerobic (APC), coliform (CC), Escherichia coli (EC), Bacillus cereus (BCC), and Staphylococcus aureus (SAC) counts, as well as tested for the incidence of Listeria monocytogenes (LM) and Salmonella (SALM) by standard plating methods. Bacterial populations attached to the cleaning and handling tools were observed by scanning electron microscopy (SEM). Ten selected gram-positive isolates were further analyzed by 16S rRNA sequence analysis and compared with isolates from filled baguettes and assorted salads. The floor mops consistently yielded the highest APCs, CCs, and ECs (5.7, 4.1, and 3.0 log CFU/g, respectively), while gloves had the lowest corresponding counts (3.6, 2.0, and 1.0 log CFU/g, respectively). Low BCCs and SACs were recorded in this study (ca. 1.2 log CFU/g), while SALM and LM were each detected in five cleaning tool samples. SEM showed rods and cocci attached to handling and cleaning tools. Furthermore, results of 16S rRNA sequence analysis indicated that several gram-positive isolates were identified as S. aureus, Staphylococcus pasteuri, Staphylococcus sciuri, and Enterococcus faecalis. Genetically similar strains (100% similarity) were isolated from cleaning and handling tools and associated ready-to-eat (RTE) foods. Cleaning and handling tools may act as reservoirs of contamination for RTE foods during preparation in retail delicatessens in South Africa. The transfer of potential pathogens, such as S. aureus, to foods from cleaning and handling tools may hold food safety implications.
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Kasidal, Kasidal, Noor Aidawati et Dewi Erika Adriani. « UJI EFEKTIFITAS AGENSIA HAYATI DALAM MENGENDALIKAN PENYAKIT LAYU BAKTERI Ralstonia solanacearum DAN MENINGKATKAN PERTUMBUHAN SERTA HASIL TANAMAN CABAI (Capsicum annum) ». EnviroScienteae 15, no 3 (3 décembre 2019) : 349. http://dx.doi.org/10.20527/es.v15i3.7427.
Texte intégralRésumé :
Chili is an important commodity for most people, because of its function in terms of improving taste and appetite. Chili was seriously developed with the support of government funds for chili farmers. The development of chili plants, has enough obstacles, especially wich caused by plant disturbing organisms whether it is pests or diseases. The important organism that disturbs chili is wilting caused by Ralstonia solanacearum. In South Kalimantan, this disease reportedly attacked chilies spread in the districts of Banjar, Banjarbaru, Barito Kuala, Tapin, Hulu Sungai Tengah and Balangan with a cumulative attack area of 15,7 ha on 2017 (South Kalimantan BPTPH Database). This disease is important because of the nature of the attack which can cause the plants to wilt suddenly all part of the plant. Plants wich attacked by bacterial wilt cannot be cured. The effort that can be done in prevention before pathogens infect the plants (Sastra, 2004). One way to overcome this problem is biological control using biological agents from the type of antagonistic bacteria Bacillus spp, Pseudomonas fluorescens, and type of antagonistic fungus Trichoderma spp. From three biological agents proven able to inhibit the development of R. solanacearum in vitro which produces a zone of inhibition as wide as 13,5 mm for Bacillus spp, 22,25 mm for Pseudomonas fluorescens and 8,42 mm for Trichoderma spp. and can increase plant height growth, chili weight, root weight, wet weight, and dry weight plants. Trichoderma spp as the best biological agents for increasing chili growth and yield.
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Zarka, Kelly A., Ria Greyling, Inge Gazendam, Dean Olefse, Kimberly Felcher, Gurling Bothma, Johan Brink, Hector Quemada et David S. Douches. « Insertion and Characterization of the cry1Ia1 Gene in the Potato Cultivar Spunta for Resistance to Potato Tuber Moth ». Journal of the American Society for Horticultural Science 135, no 4 (juillet 2010) : 317–24. http://dx.doi.org/10.21273/jashs.135.4.317.
Texte intégralRésumé :
Potato tuber moth (Phthorimaea operculella) is a serious pest of potatoes in tropical and subtropical regions of the world, including South Africa. The cry1Ia1 gene (from Bacillus thuringiensis) under the control of the 35S cauliflower mosaic virus promoter was transformed into the potato (Solanum tuberosum) cultivar Spunta to develop a cultivar with resistance to potato tuber moth for release in South Africa. Two transformation events, ‘SpuntaG2’ and ‘SpuntaG3’, were selected and subjected to extensive molecular analyses as required by the regulatory agencies of South Africa. Southern hybridization experiments indicated that ‘SpuntaG2’ and ‘SpuntaG3’ had one and three copies of the cry1Ia1 gene, respectively, and that the gene insertion was stable through multiple clonal generations. Furthermore, the sequence of the cry1Ia1 gene in ‘SpuntaG2’ was compared with the known sequence of the cry1Ia1 gene and found to be identical. Polymerase chain reaction (PCR) amplification using primers for plasmid “backbone” genes demonstrated that ‘SpuntaG2’ contained no backbone plasmid genes, whereas ‘SpuntaG3’ contained several backbone plasmid genes. Therefore, further analyses were limited to ‘SpuntaG2’, and event-specific primers were developed for this cultivar. Analysis of the left and right border regions in ‘SpuntaG2’ demonstrated that the insertion of the cry1Ia1 gene did not disrupt any functional genes nor did it create new open reading frames that encoded proteins with a significant match to the non-redundant sequence database queried by the BLASTP program. Enzyme-linked immunoabsorbent assays (ELISA) tests indicate that the cry1Ia1 gene was expressed at a mean concentration of 2.24 μg·g−1 fresh weight in leaf tissue and 0.12 μg·g−1 fresh weight in tubers. This study demonstrates the extensive molecular characterization that is necessary to apply for deregulation of a genetically modified crop and these data have been used in a regulatory package for the general release of ‘SpuntaG2’.
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Simonovska, Ljiljana, Iva Paneva et Gordana Panova. « CONTROL OF INFECTION FROM NOSOCOMIAL TRANSMISSION OF TUBERCULOSIS ». Knowledge International Journal 28, no 2 (10 décembre 2018) : 495–500. http://dx.doi.org/10.35120/kij2802495s.
Texte intégralRésumé :
Tuberculosis (TB) is still a huge health problem in the world. According to the World Health Organization (WHO), in 2015, 10.4 million new tuberculosis cases were registered. Most of the newly reported cases of TB are concentrated in 6 countries in the world: India, Indonesia, China, Nigeria, Pakistan and South Africa. In 2015, 1.8 million people died of TB. Among deaths 140,000 were children (1) By implementing the WHO strategy, known as Short Term Treatment Procedures under Direct Surveillance (DOT), almost all patients with tuberculosis can be treated. At the base of the DOT, the strategy is applied to short-term regimens under the direct control of health workers .Transmission of infection in tuberculosis is usually an aerobic pathway.Recent research in developing countries has shown that health care professionals (CARs) who take care of infectious TB patients have significantly higher isk of getting infected and getting sick from TB Therefore, WHO makes recommendations and guidelines to provide effective measures to prevent TB infection between the care professionals.These recommendations are based on a three-level control of the infection, consisting of administrative control, environmental control and personal protection of the respiratory organs. According to the basic healthcare activity provided by the Institute for Lung Disease and Tuberculosis (TB) in terms of diagnosing, treating and preventing tuberculosis, the working staff and / or patients coming to the Institute for various services are at risk of infection with tuberculosis bacteria. Therefore, consistent implementation of the measures recommended by the WHO and set out in the Control Program the infection of the nosocomial transmission of tuberculosis.The program for control of nosocomial infection with tuberculosis bacteria (MT) in the Institute should be realized with activities, hierarchically divided into three, оr four levels: managerial (organizational) activities at the level of a health institution, administrative measures, which reduce the risk of exposure to infection, environmental control measures, which prevents the risk of drooping way of spreading respiratory infections with MT and measures of personal protection against infection, which reduces the risk of inhalation of infectious particles.
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Oluseyi Osunmakinde, Cecilia, Ramganesh Selvarajan, Bhekie B. Mamba et Titus A. M. Msagati. « Profiling Bacterial Diversity and Potential Pathogens in Wastewater Treatment Plants Using High-Throughput Sequencing Analysis ». Microorganisms 7, no 11 (29 octobre 2019) : 506. http://dx.doi.org/10.3390/microorganisms7110506.
Texte intégralRésumé :
Next-generation sequencing provides new insights into the diversity and structure of bacterial communities, as well as the fate of pathogens in wastewater treatment systems. In this study, the bacterial community structure and the presence of pathogenic bacteria in three wastewater treatment plants across Gauteng province in South Africa were studied. The physicochemical results indicated that the quality of wastewater varies considerably from one plant to the others. Proteobacteria, Actinobacteria, Firmicutes, and Chloroflexi were the dominant phyla across the three wastewater treatment plants, while Alphaproteobacteria, Actinobacteria, Bacilli, and Clostridia were the dominant classes. The dominant bacterial functions were highly associated with carbohydrate, energy, and amino acid metabolism. In addition, potential pathogenic bacterial members identified from the influent/effluent samples included Roseomonas, Bacillus, Pseudomonas, Clostridium, Mycobacterium, Methylobacterium, and Aeromonas. The results of linear discriminant analysis (LDA) effect size analysis also confirmed that these bacterial pathogens were significantly abundant in the wastewater treatment systems. Further, the results of this study highlighted that the presence of bacterial pathogens in treated effluent pose a potential contamination risk, transmitted through soil, agriculture, water, or sediments. There is thus a need for continuous monitoring of potential pathogens in wastewater treatment plants (WWTPs) in order to minimize public health risk.
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Mariano, V., C. M. E. McCrindle, B. Cenci-Goga et J. A. Picard. « Case-Control Study To Determine whether River Water Can Spread Tetracycline Resistance to Unexposed Impala (Aepyceros melampus) in Kruger National Park (South Africa) ». Applied and Environmental Microbiology 75, no 1 (31 octobre 2008) : 113–18. http://dx.doi.org/10.1128/aem.01808-08.
Texte intégralRésumé :
ABSTRACT A case-control study was performed in the Kruger National Park (KNP), South Africa, to find out whether impala (Aepyceros melampus) were more likely to harbor tetracycline-resistant Escherichia coli (TREC) in their feces when they drank from rivers that contained these bacteria than when they drank from rivers that were uncontaminated with TREC. The following five perennial rivers were selected: the Crocodile, the Letaba, the Olifants, the Sabie, and the Sand. Samples of river water (n = 33) and feces (n = 209), collected at 11 different sites, were cultured for E. coli. The resulting colonies were screened for tetracycline resistance by use of the Lederberg replica plating method (breakpoint, 4 mg/liter). A resistant and/or a susceptible isolate was then selected from each sample and subjected to the CLSI MIC broth microdilution test for tetracyclines. Among the 21 water specimens contaminated by E. coli, 19.05% (n = 4) were found to be resistant by the MIC method (breakpoint, ≥8 mg/liter). This led to the Crocodile, Olifants, and Letaba rivers being classified as TREC positive. Among the 209 impala feces sampled, 191 were positive for the presence of E. coli (91.38%). Within these (n = 191), 9.95% (n = 19) of the isolates were shown to be TREC by the MIC method. It was found that 1.11% (n = 1) of the E. coli isolates cultured from the feces of the control group (n = 90) were TREC, in comparison with 17.82% (n = 18) of those in feces from the exposed group (n = 101). The calculation of the odds ratio showed that impala drinking from TREC-contaminated rivers were 19.3 (2.63 to 141.69) times more likely to be infected with TREC than were unexposed impala. This is a significant finding, indicating that surface water could be a possible source of antimicrobial resistance in na�ve animal populations and that impala could act as sentinels for antimicrobial resistance.
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Wassermann, Birgit, Lise Korsten et Gabriele Berg. « Plant Health and Sound Vibration : Analyzing Implications of the Microbiome in Grape Wine Leaves ». Pathogens 10, no 1 (12 janvier 2021) : 63. http://dx.doi.org/10.3390/pathogens10010063.
Texte intégralRésumé :
Understanding the plant microbiome is a key for plant health and controlling pathogens. Recent studies have shown that plants are responsive towards natural and synthetic sound vibration (SV) by perception and signal transduction, which resulted in resistance towards plant pathogens. However, whether or not native plant microbiomes respond to SV and the underlying mechanism thereof remains unknown. Within the present study we compared grapevine-associated microbiota that was perpetually exposed to classical music with a non-exposed control group from the same vineyard in Stellenbosch, South Africa. By analyzing the 16S rRNA gene and ITS fragment amplicon libraries we found differences between the core microbiome of SV-exposed leaves and the control group. For several of these different genera, e.g., Bacillus, Kocuria and Sphingomonas, a host-beneficial or pathogen-antagonistic effect has been well studied. Moreover, abundances of taxa identified as potential producers of volatile organic compounds that contribute to sensory characteristics of wines, e.g., Methylobacterium, Sphingomonas, Bacillus and Sporobolomyces roseus, were either increased or even unique within the core music-exposed phyllosphere population. Results show an as yet unexplored avenue for improved plant health and the terroir of wine, which are important for environmentally friendly horticulture and consumer appreciation. Although our findings explain one detail of the long-term positive experience to improve grapevine’s resilience by this unusual but innovative technique, more mechanistic studies are necessary to understand the whole interplay.
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Bumunang, Emmanuel W., Collins N. Ateba, Kim Stanford, Yan D. Niu, Y. Wang et Tim A. McAllister. « Activity of Bacteriophage and Complex Tannins against Biofilm-Forming Shiga Toxin-Producing Escherichia coli from Canada and South Africa ». Antibiotics 9, no 5 (15 mai 2020) : 257. http://dx.doi.org/10.3390/antibiotics9050257.
Texte intégralRésumé :
Bacteriophages, natural killers of bacteria, and plant secondary metabolites, such as condensed tannins, are potential agents for the control of foodborne pathogens. The first objective of this study evaluated the efficacy of a bacteriophage SA21RB in reducing pre-formed biofilms on stainless-steel produced by two Shiga toxin-producing Escherichia coli (STEC) strains, one from South Africa and the other from Canada. The second objective examined the anti-bacterial and anti-biofilm activity of condensed tannin (CT) from purple prairie clover and phlorotannins (PT) from brown seaweed against these strains. For 24-h-old biofilms, (O113:H21; 6.2 log10 colony-forming units per square centimeter (CFU/cm2) and O154:H10; 5.4 log10 CFU/cm2), 3 h of exposure to phage (1013 plaque-forming units per milliliter (PFU/mL)) reduced (p ≤ 0.05) the number of viable cells attached to stainless-steel coupons by 2.5 and 2.1 log10 CFU/cm2 for O113:H21 and O154:H10, respectively. However, as biofilms matured, the ability of phage to control biofilm formation declined. In biofilms formed for 72 h (O113:H21; 5.4 log10 CFU/cm2 and O154:H10; 7 log10 CFU/cm2), reductions after the same duration of phage treatment were only 0.9 and 1.3 log10 CFU/cm2 for O113:H21 and O154:H10, respectively. Initial screening of CT and PT for anti-bacterial activity by a microplate assay indicated that both STEC strains were less sensitive (p ≤ 0.05) to CT than PT over a concentration range of 25–400 µg/mL. Based on the lower activity of CT (25–400 µg/mL), they were not further examined. Accordingly, PT (50 µg/mL) inhibited (p ≤ 0.05) biofilm formation for up to 24 h of incubation at 22 °C, but this inhibition progressively declined over 72 h for both O154:H10 and O113:H21. Scanning electron microscopy revealed that both SA21RB and PT eliminated 24 h biofilms, but that both strains were able to adhere and form biofilms on stainless-steel coupons at longer incubation times. These findings revealed that phage SA21RB is more effective at disrupting 24 than 72 h biofilms and that PT were able to inhibit biofilm formation of both E. coli O154:H10 and O113:H21 for up to 24 h.
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Mangwende, E., J. B. Kalonji Kabengele, M. Truter et T. A. S. Aveling. « First Report of White Rust of Rocket (Eruca sativa) Caused by Albugo candida in South Africa ». Plant Disease 99, no 2 (février 2015) : 290. http://dx.doi.org/10.1094/pdis-09-14-0947-pdn.
Texte intégralRésumé :
Garden rocket (Eruca sativa syn.: E. vesicaria subsp. sativa (Mill) Thell.) is an annual plant of the Brassicaceae grown for fresh consumption as a salad vegetable. During winter (May to July) of 2013 and 2014 in South Africa, typical symptoms of white rust were observed in two commercial crops (each ~0.5 ha) of the garden rocket cv. Rucola coltivata in Centurion, Gauteng Province, at 33 and 80% incidence, respectively. Symptomatic leaves were deposited in the National Collection of Fungi, Plant Protection Research Institute, Agricultural Research Council, Pretoria, South Africa (PREM 61073). Early infections appeared as white to cream, blister-like sori on the lower leaf surfaces, and pale yellow lesions on the corresponding upper leaf surfaces. Later stages of infection were characterized by coalescing of lesions into large, irregular, necrotic blotches and development of additional sori on the petioles and stems. Sporangiophores were hyaline, clavate or cylindrical, and measured 24 to 30 × 11 to 14 μm (n = 50). Sporangia developed in basipetal chains and were hyaline, globose or polyangular, and 15 to 20 μm (n = 100). Based on these morphological characters and the host plant, the pathogen was identified as Albugo candida (Pers.) Kunze (2). Genomic DNA was extracted using the DNeasy Plant Mini DNA extraction kit (Qiagen) from sori containing sporangia collected from naturally infected leaves, according to the manufacturer's specifications. The internal transcribed spacer (ITS) region of ribosomonal DNA (rDNA) and the cytochrome c oxidase subunit II (COX2) region were amplified and sequenced (1). The ITS (GenBank Accession No. KM588081) and COX2 (KM588082) sequences confirmed identity of the pathogen as A. candida with 100% homology to the corresponding sequences of several A. candida isolates, including DQ418503 for the ITS sequence and DQ418514 for the COX2 sequence, of a voucher specimen of A. candida on E. sativa (BPI 184870) from Pakistan. Inoculum was prepared by scraping sporangia from infected leaves of the cv. Rucola coltivata collected from the 2014 field and placing the material in sterilized, distilled water (SDW) for 12 h at 5°C to induce zoospore formation. Pathogenicity tests were performed by spraying a suspension of 1 × 105 sporangia/ml onto each of 10 5-week-old rocket seedlings of the cv. Rucola coltivata. Ten additional seedlings were inoculated similarly with SDW to serve as a control treatment. The plants were maintained at 12 to 15°C and 95% RH for 72 h (3) before being moved to a shaded greenhouse at 20 to 24°C and 90% RH. Control plants remained symptomless, whereas white rust symptoms similar to those observed in the original fields developed on leaves of inoculated seedlings 10 to 14 days later, demonstrating that A. candida was the causal agent of the disease on E. sativa. To our knowledge, this is the first report of A. candida infecting garden rocket in South Africa. References: (1) Y.-J. Choi et al. Mol. Phylogenet. Evol. 40:400, 2006. (2) K. Mukerji. Descriptions of Pathogenic Fungi and Bacteria No. 458. CMI, Kew, Surrey, UK, 1975. (3) M. J. Sullivan et al. Plant Dis. 86:753, 2002.
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Sandoval Vergara, Ana, Marlon Farfán Córdova, Marco Leoncio Salazar Castillo, Icela Marissa Rodríguez Haro et Ana Paula Vizconde Rodríguez. « Antibacterial effect of the hydroalcoholic extract of Mauritia flexuosa leaves on gram-negative and gram-positive bacteria ». F1000Research 8 (23 août 2019) : 1487. http://dx.doi.org/10.12688/f1000research.19151.1.
Texte intégralRésumé :
Background: Plant-derived compounds are sometimes used as substitutes for pharmaceuticals. Mauritia flexuosa is a palm tree that is widely distributed in South America, especially in the Amazon region. The San Martín region of Peru, in which this species of the Arecaceae family is found, has great biological diversity and there is economic potential in the utilization of natural resources in the region. Methods: In this study, the antibacterial effect of the hydroalcoholic extract of Mauritia flexuosa leaves was evaluated for gram-positive bacteria Staphylococcus aureus ATCC 25923 and Bacillus subtilis ATCC 6633 and gram-negative Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853 and Salmonella enterica subsp. enterica ser. Typhi ATCC 11011. Mauritia flexuosa leaves were used to prepare concentrations of 10, 20, 40 and 60mg/ml. Phytochemical analysis was performed to identify secondary metabolites in the plants. For the experiment, 10 Mueller-Hinton agar plates were prepared and 1ml of bacterial inoculum, standardized to 0.5 McFarland, was added to each plate. The hydroalcoholic extract was added via the diffusion method, making five holes of 5mm each (four with extract concentrations and one with distilled water as a control group), and the plates were incubated for 24 hours at 36°C. The inhibition halo was measured in mm using a digital vernier caliper. Results: For gram-negative bacteria, an antibacterial effect was demonstrated for Pseudomonas aeruginosa only, at an extract concentration of 60mg/ml, with an inhibition halo of 14.8 mm. For gram-positive bacteria Baccillus subtilis and Staphylococcus aureus, an antibacterial effect was demonstrated at an extract concentration of 60mg/ml, with inhibition halos of 13.2mm and 15.4mm in diameter, respectively. Conclusion: It can be concluded that the hydroalcoholic extract of Mauritia flexuosa does not inhibit bacterial growth for gram-negative bacteria Salmonella Typhi and Escherichia coli.
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Zhou, X. G. « First Report of Bacterial Panicle Blight of Rice Caused by Burkholderia glumae in South Africa ». Plant Disease 98, no 4 (avril 2014) : 566. http://dx.doi.org/10.1094/pdis-09-13-0913-pdn.
Texte intégralRésumé :
In April 2013, upright, straw-colored panicles were observed in rice (Oryza sativa L.) fields with center pivot sprinkler irrigation at Ukulima farm in Limpopo Province, South Africa. Affected panicles contained florets that initially exhibited discoloration ranging from light green to light brown on the basal portion of the glumes and later developed a reddish-brown margin separating this area from the rest of the glume that became straw-colored. The stems of infected florets remained green. Affected grains were partially filled or aborted, causing panicles to remain upright. These symptoms appeared on approximately 25% of the rice plants of the varieties Presidio and WAB56-104. A gram-negative, rod-shaped bacterium was isolated consistently from symptomatic panicles. These strains produced circular, smooth-margined, convex colonies on King's B medium (KB) with a yellowish-green, diffusible non-fluorescent pigment. Four strains, two from each of the two varieties, were selected for physiological, molecular, and pathogenicity assays. These strains grew on nutrient-broth yeast (NBY) agar at 40°C and in NBY amended with 3% NaCl. They utilized acetate, adonitol, and citrate, and were positive for gelatin hydrolysis, but negative for oxidase and arginine dihydrolase. These morphological and physiological data indicate that the characteristics of these strains were similar to those of Burkholderia glumae. The strains were further verified using B. glumae-specific PCR method (2). In a greenhouse, 12 panicles each of Presidio and WAB56-104 were spray-inoculated at the flowering stage with a bacterial suspension (108 CFU/ml) of each strain generated from cultures grown on KB at 30°C for 24 h. Twelve panicles of each variety treated in the same way with sterile water served as controls. After inoculation, treated panicles were covered with transparent polyethylene bags and maintained in the greenhouse with temperatures ranging from 24 to 35°C. After 2 days, the polyethylene bags were removed. Symptoms similar to those observed in the field developed on all the panicles inoculated with each strain by 10 days of inoculation. No symptoms were observed on the control panicles. Bacteria with the same morphological and cultural characteristics of B. glumae were consistently re-isolated from diseased panicles. All eight randomly selected, re-isolated strains were confirmed to be B. glumae based on the B. glumae-specific PCR and physiological assays described above. This pathogenicity experiment was repeated once with similar results. This is the first report of bacterial panicle blight of rice caused by B. glumae in South Africa. Overhead sprinkler irrigation appeared to promote the development and spread of the disease. Since the bacterium is seedborne (3) and there are no acceptable levels of resistance available in commercial varieties, bacterial panicle blight poses a threat to rice production. This bacterium was first described in Japan as the causing agent of grain rot and seedling rot on rice grown under flood irrigation conditions (1). Bacterial panicle blight caused by B. glumae has since been reported in China, Korea, Latin America, the Philippines, and the United States (2). References: (1) K. Goto and K. Ohata. Ann. Phytopathol. Soc. Jpn. 21:46, 1956. (2) R. Nandakumar et al. Plant Dis. 93:896, 2009. (3) R. J. Sayler et al. Plant Dis. 90:603, 2006.
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Gallego, Juan R., Jesús Guerrero-Manzano, Francisco J. Fernández-Maldonado et Tomas Cabello. « Susceptibility of the egg parasitoid Trichogramma achaeae (Hymenoptera : Trichogrammatidae) to selected insecticides used in tomato greenhouses ». Spanish Journal of Agricultural Research 17, no 2 (26 juillet 2019) : e1009. http://dx.doi.org/10.5424/sjar/2019172-14413.
Texte intégralRésumé :
The South American tomato moth Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is a pest species of great economic importance in tomatoes, both in greenhouses and in open-air crops. This importance has increased in recent years because it has been introduced in many countries in Europe, Africa, and Asia. Insecticides different active ingredients and biological control agents are being used in the control of this pest species. This implies the need to make both groups compatible within IPM programmes. Therefore, the objective of this work was to study the compatibility between different insecticides and the use of the egg parasitoid Trichogramma achaeae Nagaraja and Nagakartti (Hymenoptera: Trichogrammatidae). Three groups of trials were carried out under laboratory and greenhouse conditions. Ten insecticides with the following active ingredient were evaluated: abamectin, azadirachtin, Bacillus thuringiensis, chlorantraniliprole, emamectin, flubendiamide, indoxacarb, methomyl, spinosad, and spiromesifen. In the results, three groups of insecticides were established based on their compatibility with the use of biological control: The first group (abamectin, B. thurigiensis, flubendiamide, indoxacarb and spiromesifen) showed a high degree of compatibility with egg parasitoid releases. The second group (azadirachtin and chlorantraniliprole, and methomyl) presented compatibility problems. Finally, the last group (emamectin, methomyl, and spinosad) did not apper to be compatible. The results found will allow a better application of IPM programmes in tomato crops for the control of this pest species.
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Retno Wardani, Hamidah, Destia Widyarani, Rany Agustin Wulandari et Damon Wicaksi. « Potential of Herbal Plants Against Mycobacterium Tuberculosis Infection ». D'Nursing and Health Journal (DNHJ) 1, no 2 (20 septembre 2020) : 44–54. http://dx.doi.org/10.36835/dnursing.v1i2.41.
Texte intégralRésumé :
Introduction: Tuberculosis is an infectious disease caused by Mycobacterium tuberculosis. The leading cause of death worldwide is responsible for 1.5 million deaths each year. The cause of tuberculosis infection is the tubercle bacillus discovered by Robert Koch in 1882. The organism causing it is Mycobacterium tuberculosis.The spread of new cases is divided in several regions including Southeast Asia and Africa, which are the regions that have the biggest contribution to the prevalence of tuberculosis. So it takes pillars and components of TB control that cover all lines. Method: This study aims to discuss the potential of herbal plants spread in Indonesia as herbal medicines that have the potential to treat tuberculosis infection. This study uses a literature study method which prepares the same as other research, but the sources and methods of data collection are by taking data from the library, reading, taking notes, and processing research materials. Result: One of the components that are currently being developed in TB infection intervention methods is the development of herbal medicines for tuberculosis control. The herbal medicines used come from garlic (Allium sativum), Centellaasiatica, beluntas leaves, Hibiscus rosasinensis L., Boechmeria virgate (Forst) Guill, tobacco leaves, Morindacitrifolia L., Javanese wood bark, Spondiaspinnata (Lf)Kurz. Conclusion: The herbal medicinal ingredients contain major chemicals such as alicin, ajoene, asiaticoside, asiatic acid, madecassic acid, and madecassoside, alkaloids, flavonoids, tannins, saponins, phenolic, and triterpenoids which have the ability to have a bactericidal effect to kill the Mycobacterium tuberculosis bacteria.
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Tamele, Isidro, Marisa Silva et Vitor Vasconcelos. « The Incidence of Marine Toxins and the Associated Seafood Poisoning Episodes in the African Countries of the Indian Ocean and the Red Sea ». Toxins 11, no 1 (21 janvier 2019) : 58. http://dx.doi.org/10.3390/toxins11010058.
Texte intégralRésumé :
The occurrence of Harmful Algal Blooms (HABs) and bacteria can be one of the great threats to public health due to their ability to produce marine toxins (MTs). The most reported MTs include paralytic shellfish toxins (PSTs), amnesic shellfish toxins (ASTs), diarrheic shellfish toxins (DSTs), cyclic imines (CIs), ciguatoxins (CTXs), azaspiracids (AZTs), palytoxin (PlTXs), tetrodotoxins (TTXs) and their analogs, some of them leading to fatal outcomes. MTs have been reported in several marine organisms causing human poisoning incidents since these organisms constitute the food basis of coastal human populations. In African countries of the Indian Ocean and the Red Sea, to date, only South Africa has a specific monitoring program for MTs and some other countries count only with respect to centers of seafood poisoning control. Therefore, the aim of this review is to evaluate the occurrence of MTs and associated poisoning episodes as a contribution to public health and monitoring programs as an MT risk assessment tool for this geographic region.
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Wymann, M. N., E. Flacio, S. Radczuweit, N. Patocchi et P. Lüthy. « Asian tiger mosquito (Aedes albopictus) - a threat for Switzerland ? » Eurosurveillance 13, no 10 (6 mars 2008) : 3–4. http://dx.doi.org/10.2807/ese.13.10.08058-en.
Texte intégralRésumé :
The Asian tiger mosquito, Aedes albopictus (Stegomya albopicta) originating from south-east Asia, has spread primarily by the trade of used tyres to the United States, Europe, Latin America and Africa [1]. In Italy, the mosquito species was first detected in Genoa in 1990 and has since spread to several parts of the country, including border areas with Switzerland [2]. In 2000, an active monitoring system was established in southern Switzerland. The first tiger mosquito was detected in the canton of Ticino in 2003 [3]. Monitoring was gradually intensified due to growing mosquito densities in northern Italy. As the long-distance migration of Ae. albopictus depends on passive transport, the monitoring system consisted of strategically positioned oviposition traps along main traffic axes, including parking lots within industrial complexes, border crossings and shopping centres. In 2007, this monitoring system consisted of over 70 checkpoints with a total of 300 traps. Bi-weekly control visits to all traps were conducted between April and November 2007. As soon as eggs were detected, the surrounding vegetation within a perimeter of about 100 metres was sprayed with permethrin against adult mosquitoes. Stagnant water was treated with Bacillus thuringiensis and in some cases with diflubenzuron to control the larval stages.