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Thi Minh Nguyet, Nguyen, Hoang Phuong Ha, Dong Van Quyen, Nguyen Ngoc Huong Tra e Le Thi Nhi Cong. "Degradation of naphthalene and pyrene by several biofilm-forming photosynthesis purple bacterial strains". Vietnam Journal of Biotechnology 18, n. 3 (28 novembre 2020): 561–70. http://dx.doi.org/10.15625/1811-4989/18/3/15322.
Testo completoAbstract (sommario):
Aromatic hydrocarbons such as naphthalene, pyrene are recalcitrant compounds found in oil contaminated areas including petroleum storage tanks, oil exploiting companies. These components are difficult to be degraded/transformed in the lack of oxygen conditions. Among anaerobic and micro-aerobic microorganisms, photosynthetic purple bacteria are the dominant group. Photosynthetic purple bacteria (PPB) are considered as aquatic organisms which are able to grow in anaerobic conditions by photosynthesis but without oxygen. This bacterial group has flexible metabolic types depending on living conditions, then they are widely distributed in nature. There are numerous publications on planktonic PPB which could use naphthalene and pyrene as carbon and energy sources. However, there is no publication on biofilm formed by PPB to degrade their aromatic compounds. In this research, 4 biofilm-forming PPB strains including DQ41, PY2, PY6 and DG12 were screened and estimated their pyrene and napthalene degradation capacity. These organisms demonstrated high biofilm forming ability. As biofilm types, their utilization efficiencies were upper 79% with the initial concentrations of naphthalene and pyrene of 200 and 250 ppm, respectively. These results may contribute to enlarge the number of biofilm-forming microorganisms to degrade/transform aromatic hydrocarbons in polluted area treatment in Vietnam.
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Banerjee, Soma, Abira Sahu, Shouvik Dutta, Rimashree Baishya e Prasanta Kumar Maiti. "Effect of different antibiotics against in vitro Staphylococcus aureus biofilm grown on chitin flakes". South Asian Journal of Experimental Biology 5, n. 1 (4 luglio 2015): 22–25. http://dx.doi.org/10.38150/sajeb.5(1).p22-25.
Testo completoAbstract (sommario):
MIC determination is the standard assay for testing the susceptibility of planktonic bacteria to antibiotics. It has been observed that biofilm grown cells express properties distinct from planktonic cells, for which antibiotics are generally not effective against biofilm forming organisms. The current study aims at comparison of the susceptibilities of biofilm grown cells to sin-gle antibiotic and in combination with others to identify those that were effective against Staphylococcus aureus biofilms. S. aureus ATCC 25923 were used for the purpose. They were grown in Tryptic Soya Broth (TSB) with chitin flakes as the inert surface to which the organisms adhered to produce the biofilm. Growth pattern of both biofilm producing and planktonic cells were studied. Viable counts were determined on Tryptic Soya Agar (TSA) plates. Different antibiotics viz. gentamicin, vancomycin, ciprofloxacin were used to determine the sensitivity of the bacterial strain. There was a marked differ-ence in antibiotic susceptibility between the planktonic and biofilm popula-tion of the organism. It was found that the biofilm colonies were more resistant to the antibiotics like ciprofloxacin, vancomycin and gentamicin than the planktonic cells. The reduction in growth of bacteria was much more for gentamicin compared to that of ciprofloxacin and vancomycin and when antibiotic combination gentamicin - vancomycin it is much more reduced. It is thus clear from the test that the antibiotic susceptibilities of planktonic populations are not necessarily applicable to the effective treatment of the same organism once a biofilm has been established.
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Lévesque, Céline M., Elena Voronejskaia, Yi-Chen Cathy Huang, Richard W. Mair, Richard P. Ellen e Dennis G. Cvitkovitch. "Involvement of Sortase Anchoring of Cell Wall Proteins in Biofilm Formation by Streptococcusmutans". Infection and Immunity 73, n. 6 (giugno 2005): 3773–77. http://dx.doi.org/10.1128/iai.73.6.3773-3777.2005.
Testo completoAbstract (sommario):
ABSTRACT Streptococcus mutans is one of the best-known biofilm-forming organisms associated with humans. We investigated the role of the sortase gene (srtA) in monospecies biofilm formation and observed that inactivation of srtA caused a decrease in biofilm formation. Genes encoding three putative sortase-dependent proteins were also found to be up-regulated in biofilms versus planktonic cells and mutations in these genes resulted in reduced biofilm biomass.
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Bhatta, Mahesh Prakash, Asmita Sapkota, Pushpa Subedi, Sunita Baniya Chhetri, Dhaka Raj Pant, Mukund Joshi, Santosh Pandit e Dipendra Raj Pandeya. "Biofilm Formation by Uropathogens and Their Susceptibility Towards Antimicrobial Therapy". Medical Journal of Shree Birendra Hospital 18, n. 1 (26 febbraio 2019): 13–22. http://dx.doi.org/10.3126/mjsbh.v18i1.20189.
Testo completoAbstract (sommario):
Introduction: Urinary tract infection (UTI) is the most common health care associated infection caused by various pathogenic bacteria. Biofilms are communities of bacteria that are held together by exopolymeric substances that protect against the antimicrobial therapy and other environmental assaults. The aim of this study was to estimate the prevalence of biofilm forming bacteria in Nepalese population and to study the emergence of antimicrobial resistance among biofilm producing bacteria in comparison to non-biofilm producing bacteria.
Methods: A total of 785 clean-caught-mid-stream urine samples were collected. After isolation and identification of uropathogens, they were further processed for detection of biofilm formation by two methods (Congo Red Agar method and Tissue Culture Plate method) as well as for antibiotic sensitivity test.
Results: Out of total collected samples, 12.74% were found to be associated with UTI, among them 67% were Escherichia coli, 10% were Klebsiella spp, 7% were Pseudomonas spp, 6% were Staphyloccous aureus, 4% were Enterobacter spp, 3% were Proteus spp, 2% were Citrobacter spp and remaining 1% was Staphylococcus saprophyticus. Among isolated organisms, the ratio of bioflim positive organism to bioflim negative organism was found to be 9:11. Nitrofurantoin, Tobramycin, Chloramphenicol, Amikacin and Imipenem were found to be significantly more sensitive in biofilm negative bacteria as compared to biofilm positive bacteria with p values of 0.000, 0.001, 0.000, 0.000 and 0.001.
Conclusions: The prevalence rate of multidrug resistance in bacterial uropathogens was higher in biofilm producers as compared to non-biofilm producers. Biofilm forming characteristic of bacteria make them more resistant to antibiotics.
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P., Prasanth, e Saravanakumari P. "DETECTION OF INTERCELLULAR ADHESION GENES (ICA) IN STAPHYLOCOCCUS AUREUS CAUSING IMPLANT ASSOCIATED INFECTIONS". International Journal of Pharmacy and Pharmaceutical Sciences 9, n. 10 (1 novembre 2017): 76. http://dx.doi.org/10.22159/ijpps.2017v9i11.20789.
Testo completoAbstract (sommario):
Objective:The complications related to implant associated infections in post-angioplasty patients were considered to increase due to biofilm formation.Methods: Genes responsible for the biofilm formation in the target organisms was investigated in the present study. The presence of the intercellular adhesion biofilm genes (icaA, icaB and icaD) was determined by the Polymerase Chain Reaction method. As preliminary investigations, standard tests, exit-site challenge test and microtitre plate method were used to study the biofilm efficiency of five different test organisms.Results: Exit-site challenge test, was used to identify the ability of test organisms to grow on a bio-materials used in the study. Among the five selected test organisms, Staphylococcus aureus showed the highest ability to colonize the stent materials with in 24h to 48h. In microtitre plate method, Staphylococcus aureus and Staphylococcus epidermidis showed high biofilm forming index values of 0.29 and 0.27 respectively. Biofilm gene studies using PCR revealed the presence of all the three ica genes (Ica A, Ica D and, Ica B) in Staphylococcus aureus. The present research finding has great significance in the treatment to implant associated infections.Conclusions: The results suggest that the virulence factors contributing to the development of infections can be revealed by understanding the presence of biofilm expression genes in the target organisms. This would also prevent dissemination of virulent bacteria in the health care centre; method also considered significant to detect healthy carriers of slime-producing staphylococci.
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Mireles, Joe Robert, Adam Toguchi e Rasika M. Harshey. "Salmonella enterica Serovar Typhimurium Swarming Mutants with Altered Biofilm-Forming Abilities: Surfactin Inhibits Biofilm Formation". Journal of Bacteriology 183, n. 20 (15 ottobre 2001): 5848–54. http://dx.doi.org/10.1128/jb.183.20.5848-5854.2001.
Testo completoAbstract (sommario):
ABSTRACT Swarming motility plays an important role in surface colonization by several flagellated bacteria. Swarmer cells are specially adapted to rapidly translocate over agar surfaces by virtue of their more numerous flagella, longer cell length, and encasement of slime. The external slime provides the milieu for motility and likely harbors swarming signals. We recently reported the isolation of swarming-defective transposon mutants of Salmonella enterica serovar Typhimurium, a large majority of which were defective in lipopolysaccharide (LPS) synthesis. Here, we have examined the biofilm-forming abilities of the swarming mutants using a microtiter plate assay. A whole spectrum of efficiencies were observed, with LPS mutants being generally more proficient than wild-type organisms in biofilm formation. Since we have postulated that O-antigen may serve a surfactant function during swarming, we tested the effect of the biosurfactant surfactin on biofilm formation. We report that surfactin inhibits biofilm formation of wild-type S. enterica grown either in polyvinyl chloride microtiter wells or in urethral catheters. Other bio- and chemical surfactants tested had similar effects.
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Cholo, Moloko C., Sipho S. M. Rasehlo, Eudri Venter, Chantelle Venter e Ronald Anderson. "Effects of Cigarette Smoke Condensate on Growth and Biofilm Formation by Mycobacterium tuberculosis". BioMed Research International 2020 (19 agosto 2020): 1–7. http://dx.doi.org/10.1155/2020/8237402.
Testo completoAbstract (sommario):
Background and Objectives. Cigarette smoke (CS) is a major risk factor contributing to the burden of tuberculosis. Little is known, however, about the effects of CS exposure on growth and persistence of Mycobacterium tuberculosis (Mtb) organisms. This issue has been addressed in the current study, which is focused on the effects of cigarette smoke condensate (CSC) on the growth and viability of Mtb planktonic and biofilm-forming cultures. Materials and Methods. The planktonic and biofilm-forming cultures were prepared in Middlebrook 7H9 and Sauton broth media, respectively, using Mtb strain, H37Rv. The effects of CSC at concentrations of 0.05-3.12 mg/L on growth, biofilm formation and structure were evaluated using microplate Alamar Blue assay, spectrophotometric procedure and scanning electron microscopy (SEM), respectively. Involvement of reactive oxygen species in CSC-mediated biofilm formation was investigated by including catalase in biofilm-forming cultures. Results. CSC did not affect the growth of planktonic bacteria, but rather led to a statistically significant increase in biofilm formation at concentrations of 0.4-3.12 mg/L, as well as in the viability of biofilm-forming bacteria at CSC concentrations of 0.2-1.56 mg/L. SEM confirmed an agglomerated biofilm matrix and irregular bacterial morphology in CSC-treated biofilms. Inclusion of catalase caused significant attenuation of CSC-mediated augmentation of biofilm formation by Mtb, implying involvement of oxidative stress. These findings demonstrate that exposure of Mtb to CSC resulted in increased biofilm formation that appeared to be mediated, at least in part, by oxidative stress, while no effect on planktonic cultures was observed. Conclusion. Smoking-related augmentation of biofilm formation by Mtb may contribute to persistence of the pathogen, predisposing to disease reactivation and counteracting the efficacy of antimicrobial chemotherapy.
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Fry, Stephen Eugene, Jeremy Eugene Ellis, Matthew Andrew Shabilla, Delyn Lorene Martinez, Renatta Schwarz, Richard Heuser e Constantine Moschonas. "Putative biofilm-forming organisms in the human vasculature: expanded and review of the literature". Phlebological Review 1 (2014): 24–37. http://dx.doi.org/10.5114/pr.2014.46050.
Testo completo
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Eid, Doaa, Ossama M. Sayed, Walaa G. Hozayen e Ahmed F. Azmy. "Battling Biofilm Forming Nosocomial Pathogens Using Chitosan and Pluronic F127". Journal of Pure and Applied Microbiology 14, n. 3 (22 settembre 2020): 1893–903. http://dx.doi.org/10.22207/jpam.14.3.28.
Testo completoAbstract (sommario):
Biofilm represents a potential strut in bacterial treatment failure. It has a dual action; it affords microbial resistance against antibiotics and facilitate transmission of pathogenic bacteria. Nosocomial bacteria pose a serious problem in healthcare units; it prolongs patient hospital stay and increases the mortality rates beside other awful economical effect. This study was planned for targeting nosocomial bacterial biofilm using natural and biologically safe compounds like Chitosan and/or Pluronic F127. Ninety-five isolates were recovered from 107 nosocomial clinical samples. Different bacterial and fungal species were detected, from which Klebsiella pneumonia (23%), Pseudomonas aeruginosa (19%), Acinetobacter baumannii (18%) and E.coli (17%) were the predominate organisms. Pseudomonas aeruginosa, Acinetobacter baumanni and Klebsiella pneumonia were the abundant antibiotic resistant strains with multi-resistance pattern of 72%, 65% and 59%, respectively. A significant percentage of these isolates were strong biofilm forming. Herein, we investigate the effect of Chitosan and Pluronic F127 alone and in combination with each other against biofilm production. Chitosan show variable degree of biofilm inhibition, while Pluronic F127 was able to retard biofilm formation by 80% to 90% in most strain. There is no significant difference (P< 0.05) between Pluronic F127 alone and its effect in combination with Chitosan.
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Pankhurst, Caroline L. "Risk Assessment of Dental Unit Waterline Contamination". Primary Dental Care os10, n. 1 (gennaio 2003): 5–10. http://dx.doi.org/10.1308/135576103322504030.
Testo completoAbstract (sommario):
Biofilms form rapidly on dental unit waterlines. The majority of the organisms in the biofilm are harmless environmental species, but some dental units may harbour opportunistic respiratory pathogens. This paper describes a risk assessment approach to analysing the hazard from biofilm organisms contaminating dental unit waterlines on the respiratory health of both the dental team and patients. The health risk from the respiratory pathogens Legionella spp, Mycobacterium spp and Pseudomonads was found to be low. Nevertheless, in order to satisfy water regulations and comply with health and safety legislation dentists should institute infection-control measures to maintain the dental unit water at the standard of less than 200 colony-forming units per ml of aerobic bacteria.
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Sayem, S. M. A., A. J. M. T. Chowdhury, M. Z. Alam e P. K. Sarker. "Antibiofilm Activity of Crude Cell Free Extract from Bacillus subtilis S01 against E. coli". Journal of Scientific Research 10, n. 2 (1 maggio 2018): 211–21. http://dx.doi.org/10.3329/jsr.v10i2.35604.
Testo completoAbstract (sommario):
Antibiofilm phenomenon has become a novel area of research for removing deleterious biofilm. In the present study, strains from different environmental sources were tested for screening antibiofilm compounds. Crude extracts from various microorganisms were evaluated for antibiofilm phenomenon through crystal violet assay and growth curve analysis. Characterization of antibiofilm compound was performed by pre-coating microtiter plate and Cell Surface Hydrophobicity experiment. Among the organisms, cell free extracts (5% v/v) from Bacillus subtilis S01 inhibited the development of E. coli PHL628 biofilm by 63%. The cell free extracts possessed no amylase activity and had no effect on the planktonic growth of biofilm forming bacteria. Moreover, no competition with quorum sensing analogues was found with the extract. Biofilm formation was more inhibited (76%) in the B. subtilis S01 extract pre-coated wells than uncoated wells (62%). However, no effect on preformed biofilm was observed with the extracts of B. subtilis S01. The extract also reduced the cell surface hydrophobicity (69%) of the biofilm forming bacteria. The present study indicated that the crude extracts of B. subtilis S01 from soil origin has anti-adherence properties towards biotic and abiotic surfaces and thus can be a potential candidate in preventing the development of biofilm.
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Tan, Li, e Creg Darby. "A Movable Surface: Formation of Yersinia sp. Biofilms on Motile Caenorhabditis elegans". Journal of Bacteriology 186, n. 15 (1 agosto 2004): 5087–92. http://dx.doi.org/10.1128/jb.186.15.5087-5092.2004.
Testo completoAbstract (sommario):
ABSTRACT Bubonic plague is transmitted by fleas whose feeding is blocked by a mass of Yersinia pestis in the digestive tract. Y. pestis and the closely related Y. pseudotuberculosis also block the feeding of Caenorhabditis elegans by forming a biofilm on the nematode head. C. elegans mutants with severe motility defects acquire almost no biofilm, indicating that normal animals accumulate the biofilm matrix as they move through a Yersinia lawn. Using the lectin wheat germ agglutinin as a probe, we show that the matrix on C. elegans contains carbohydrate produced by Yersinia. The carbohydrate is present in bacterial lawns prior to addition of nematodes, indicating that biofilm formation does not involve signaling between the two organisms. Furthermore, biofilm accumulation depends on continuous C. elegans exposure to a lawn of Yersinia bacteria.
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Nhi Cong, Le Thi, Cung Thi Ngoc Mai, Vu Thi Thanh, Le Phi Nga e Nghiem Ngoc Minh. "Application of a biofilm formed by a mixture of yeasts isolated in Vietnam to degrade aromatic hydrocarbon polluted wastewater collected from petroleum storage". Water Science and Technology 70, n. 2 (19 maggio 2014): 329–36. http://dx.doi.org/10.2166/wst.2014.233.
Testo completoAbstract (sommario):
In this study, three good biofilm-forming yeast strains, including Candida viswanathii TH1, Candida tropicalis TH4 and Trichosporon asahii B1, were isolated from oil-contaminated water and sediment samples collected in coastal zones of Vietnam. These strains were registered in the GenBank database with the accession numbers JX129175, JX129176 and KC139404 for strain TH1, TH4 and B1, respectively. The biofilm formed by a mixture of these organisms degraded 90, 85, 82 and 67% of phenol, naphthalene, anthracene and pyrene, respectively, after a 7-day incubation period using an initial concentration of 600 ppm phenol and 200 ppm of each of the other compounds. In addition, this biofilm completely degraded these aromatic compounds, which were from wastewater collected from petroleum tanks in Do Xa, Hanoi after 14 days of incubation based on gas chromatography mass spectrometry analysis. To the best of our knowledge, reports on polycyclic aromatic hydrocarbon and phenol degradation by biofilm-forming yeasts are limited. The results obtained indicate that the biofilm formed by multiple yeast strains may considerably increase the degradation efficiency of aromatic hydrocarbon compounds, and may lead to a new approach for eliminating petroleum oil-contaminated water in Vietnam.
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Sathyanarayanan, Madhu Bala, Reneta Balachandranath, Yuvasri Genji Srinivasulu, Sathish Kumar Kannaiyan e Guruprakash Subbiahdoss. "The Effect of Gold and Iron-Oxide Nanoparticles on Biofilm-Forming Pathogens". ISRN Microbiology 2013 (25 settembre 2013): 1–5. http://dx.doi.org/10.1155/2013/272086.
Testo completoAbstract (sommario):
Microbial biofilms on biomaterial implants or devices are hard to eliminate by antibiotics due to their protection by exopolymeric substances that embed the organisms in a matrix, impenetrable for most antibiotics and immune-cells. Application of metals in their nanoparticulated form is currently considered to resolve bacterial infections. Gold and iron-oxide nanoparticles are widely used in different medical applications, but their utilisation to eradicate biofilms on biomaterials implants is novel. Here, we studied the effect of gold and iron oxide nanoparticles on Staphylococcus aureus and Pseudomonas aeruginosa biofilms. We report that biofilm growth was reduced at higher concentrations of gold and iron-oxide nanoparticles compared to absence of nanoparticles. Thus nanoparticles with appropriate concentration could show significant reduction in biofilm formation.
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Premanath, Ramya, Sarika Suresh, Prathiksha P. Alva e Akash S. K. "Biofilm Forming Abilities of Microorganisms Associated with Diabetic Wound Infection: A Study from a Tertiary Care Hospital". Biomedical and Pharmacology Journal 12, n. 2 (9 maggio 2019): 669–76. http://dx.doi.org/10.13005/bpj/1687.
Testo completoAbstract (sommario):
Diabetes mellitus, a chronic metabolic disease is increasing worldwide. Diabetic foot infections are one of the most feared and bothersome complications of diabetes caused by different genera of bacteria. There is an increasing evidence which demonstrates the presence of biofilm former's in chronic diabetic foot ulcers which contribute to the development of antibiotic-resistant strains and treatment failure. The present study aimed at isolating bacteria from diabetic wounds, to check for its antibiotic susceptibility and biofilm forming ability. From the diabetic wounds, isolates belonging to the genera of Staphylococcus, Pseudomonas, Klebsiella, Esherichia, Vibrio, Acinetobacter and Citrobacter were recovered. To the best of our knowledge, Vibrio parahaemolyticus was isolated for the first time from diabetic ulcer. Antibiotic sensitivity profile of the organisms infers the presence of multidrug-resistant strains. Majority of bacteria isolated were found to be biofilm formers. High biofilm former's were observed in strains of P. aeruginosa, S. aureus and Klebsiella spp. There was significant association between incubation time and intensity of biofilm formation in P. aeruginosa [ᵡ2 (p< 0.05) = 0.001)], Staphylococcus spp. [ᵡ2 (p< 0.05) = 0.023)] and Acinetobacter spp. [ᵡ2 (p< 0.05) = 0.018)]. The presence of biofilm forming multidrug-resistant bacteria infers the chronic nature of diabetic wounds.
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Tall, B. D., K. S. George, R. T. Gray e H. N. Williams. "Bacterial biofilm behavior in water-supply lines of dental units". Proceedings, annual meeting, Electron Microscopy Society of America 50, n. 1 (agosto 1992): 882–83. http://dx.doi.org/10.1017/s0424820100124811.
Testo completoAbstract (sommario):
Studies of bacterial behavior in many environments have shown that most organisms attach to surfaces, forming communities of microcolonies called biofilms. In contaminated medical devices, biofilms may serve both as reservoirs and as inocula for the initiation of infections. Recently, there has been much concern about the potential of dental units to transmit infections. Because the mechanisms of biofilm formation are ill-defined, we investigated the behavior and formation of a biofilm associated with tubing leading to the water syringe of a dental unit over a period of 1 month.
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Jayarani Manikandan, Jaikumar S e Sandhya Rani T. "Identification of biofilm-producing microorganism’s and drug susceptibility pattern from diabetic foot ulcer patients at Puducherry". International Journal of Research in Pharmaceutical Sciences 11, n. 4 (24 dicembre 2020): 7353–57. http://dx.doi.org/10.26452/ijrps.v11i4.3916.
Testo completoAbstract (sommario):
Diabetes mellitus is a significant health problem worldwide that affects approximately 171 million people; severe complications lead to the development of diabetic foot ulcers. Diabetic ulcer infections are mainly polymicrobial in nature and multidrug-resistant (MDR), which is capable of forming a biofilm, which is the important virulence factor results in treatment failure. The main objectives of this study to investigate the etiologic agents of diabetic foot infections, their antimicrobial resistance and biofilm formation. A total of 200 patient samples were taken from diabetic foot ulcer patients between September 2015 and February 2016. Isolation and identification of microorganism were made according to standard microbiological procedures. Antibiotic Susceptibility testing performed by Kirby Bauer disc diffusion method and the biofilm production was performed by the tube method and Congo Red Method. Out of 200 samples processed, 110 (55%) were polymicrobial, 50 (25%) monomicrobial and 40(20 %)culture Sterile. The most common organism isolated were 82(39%) Pseudomonas aeruginosa,45(21%) Staphylococcus aureus, 48(23%) Candida sp followed by others. Biofilm production was seen in 112 (53%) of the isolates. Antimicrobial drug resistance was higher among 92(82%) biofilm producers than non-biofilm 20(18%) producing microorganisms. Organisms isolated from chronic diabetic foot ulcers cases were multidrug-resistant and biofilm producers. Our study shows the importance of biofilm screening with the usual antibiogram, as a routine technique in diabetic foot ulcers patients for effective treatment.
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Narváez-Zapata, J., C. C. Tebbe e B. O. Ortega-Morales. "Molecular diversity and biomass of epilithic biofilms from intertidal rocky shores in the Gulf of Mexico". Biofilms 2, n. 2 (aprile 2005): 93–103. http://dx.doi.org/10.1017/s147905050500178x.
Testo completoAbstract (sommario):
Epilithic biofilms play key roles in rocky shore ecosystems. The diversity and biomass of epilithic biofilms were determined along a subtropical intertidal rocky shore at Xpicob, Southern Gulf of Mexico (Campeche, Mexico). Biofilm diversity was assessed by polymerase chain reaction (PCR) amplification of partial 16 S rRNA genes using single-strand conformation polymorphism (SSCP). Triplicate 2 cm×2 cm biofilm samples per site were taken randomly from 0.6 m×0.6 m quadrats located in two sampling sites, established 20 m apart within a homogeneous calcareous intertidal platform. Twenty-two partial rRNA sequences, belonging to four bacterial divisions (Cyanobacteria, Bacteroidetes, Actinobacteria and Proteobacteria), were recovered from these biofilms; of these, cyanobacteria were the most abundant (41%). The occurrence of cyanobacterial sequences in most samples, along with the detection of high levels of chlorophyll a and phycobiliprotein, indicates that these organisms are dominant within the biofilms. Consistent with previous reports, thick-sheathed cyanobacteria such as those found in this study (Xenococcus, Myxosarcina and Chroococcidiopsis) are typical in habitats in intertidal zones. In addition, most of the detected organisms from other bacterial lineages had closest relatives displaying biofilm phenotypes that suggested stressful conditions (i.e. desiccation) prevailed in the intertidal shores; this was selecting for biofilm-forming or thick-sheathed organisms as an ecological adaptation to withstand the conditions. Unweighted pair-group method with arithmetic mean (UPGMA) analysis of SSCP profiles indicated that there was significant spatial heterogeneity in biofilm community composition across different scales of analysis and that this heterogeneity was related to the distance at which samples were taken. This analysis showed that certain organisms appeared to be station specific and that the biofilm community structure varied even on a small scale (1 cm). Since no significant differences in bulk sea water or substratum physicochemistry were observed, these results suggest that small-scale variability of environmental conditions, surface properties and/or biological interactions (i.e. allelopathy) may be important factors structuring these biofilm communities.
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Shrestha, Rajani, N. Nayak, D. R. Bhatta, D. Hamal, S. H. Subramanya e S. Gokhale. "Drug Resistance and Biofilm Production among Pseudomonas aeruginosa Clinical Isolates in a Tertiary Care Hospital of Nepal". Nepal Medical College Journal 21, n. 2 (2 agosto 2019): 110–16. http://dx.doi.org/10.3126/nmcj.v21i2.25109.
Testo completoAbstract (sommario):
Clinical isolates of Pseudomonas aeruginosa often exhibit multidrug resistance due to their inherent ability to form biofilms. Drug resistance in Ps. aeruginosa is a major clinical problem, especially in the management of patients with nosocomial infections and those admitted to ICUs with indwelling medical devices. To evaluate the biofilm forming abilities of the clinical isolates of Ps. aeruginosa and to correlate biofilm formation with antibiotic resistance. A total of 90 consecutive isolates of Ps. aeruginosa obtained from various specimens collected from patients visiting the Manipal Teaching Hospital, Pokhara, Nepal between January 2018 - October 2018 were studied. Isolates were identified by standard microbiological methods. Antibiotic susceptibility testing was performed by Kirby-Bauer disc diffusion method. All the isolates were tested for their biofilm forming abilities by employing the tissue culture plate assay. Of the 90 Ps. aeruginosa isolates, maximum i.e 42 (46.6%) were from patients in the age group of > 50 years. Majority (30; 33.3%) of the isolates were obtained from sputum samples. However, percentage isolation from other specimens like urine, endotracheal tube (ETT), pus, eye specimens and blood were 18.9%, 16.7%, 16.7%, 7.8% and 6.7% respectively. All the isolates were sensitive to polymixin B and colistin, 91.1% of the organisms were sensitive to imipenem, and more than 80% to aminoglycosides (80% to gentamicin, 83.3% to amikacin). A total of 29 (32.2%) organisms were biofilm producers. Maximum numbers of biofilm producing strains were obtained from ETT (8 of 15; 53.3%), pus (8 of 15; 53.3%) and blood (2 of 6; 33.3%) i.e from all invasive sites. None of the isolates from noninvasive specimens such as conjunctival swabs were biofilm positive. Significantly higher numbers of biofilm producers (23 of 29; 79.3%) were found to be multidrug resistant as compared to non-biofilm (6 of 61; 9.8%) producers (p=0.000). Ps. aeruginosa colonization leading to biofilm formation in deep seated tissues and on indwelling devices is a therapeutic challenge as majority of the isolates would be recalcitrant to commonly used antipseudomonal drugs. Effective monitoring of drug resistance patterns in all Pseudomonas clinical isolates should be a prerequisite for successful patient management.
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Majumdar, Udayan, Thrisha Alexander, Morris Waskar e Manoj V. Dagaonkar. "Effect of biofilm on colloid attachment in saturated porous media". Water Science and Technology 70, n. 2 (7 maggio 2014): 241–48. http://dx.doi.org/10.2166/wst.2014.197.
Testo completoAbstract (sommario):
Biofilm plays an important role in controlling the transport of colloids in a porous media. Biofilms are formed when micro-organisms come in contact with substrates, and are able to attach and grow with availability of nutrients. The microorganisms get embedded in a matrix of the substrate and extracellular polymeric substances which are responsible for the morphology, physico-chemical properties, structure and coherence of the biofilm. In this study, the effect of biofilm and its aging on colloid removal was studied on a glass bead column. Oocysts, polystyrene microspheres and inorganic colloids were used as colloidal particles. Pseudomonas aeruginosa was used as a model biofilm-forming microorganism. Presence of biofilm significantly enhanced colloid removal in the column. After 3 weeks, almost complete colloid removal was observed. The formation of biofilm was confirmed by various physical characterization techniques. During the extended aging study, biofilm sloughed off under shear stress. The loss of biofilm was higher during the early stage of its growth, and subsequently slowed down probably due to the formation of a more rigid biofilm. This research indicates that biofilm formation, maturation and sloughing-off play a critical role in colloid removal through porous media.
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Nithya Deva Krupa, A., e Vimala Raghavan. "Biosynthesis of Silver Nanoparticles UsingAegle marmelos(Bael) Fruit Extract and Its Application to Prevent Adhesion of Bacteria: A Strategy to Control Microfouling". Bioinorganic Chemistry and Applications 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/949538.
Testo completoAbstract (sommario):
Marine biofilms formed due to adhesion of bacteria and other microorganisms on submerged surfaces are generally considered to be a major form of microfouling. Subsequent attachment of larvae of higher organisms like barnacles, mussels, and so forth, on marine biofilms, causes macrofouling. Several approaches have been used to prevent micro- and macrofouling. Silver nanoparticles (AgNPs) are known to exhibit strong inhibitory and antimicrobial activity. Biological synthesis of AgNPs is rapidly gaining importance due to its growing success. Hence, the present study is focused on the biosynthesis of AgNPs using fruit extract ofAegle marmelosand its characterization through UV-Vis spectrophotometer, X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), and atomic force microscopy (AFM). Further isolation and identification of marine biofilm forming bacteria were carried out through 16S rDNA analysis. The antimicrofouling effect of the biosynthesized AgNPs was tested against marine biofilm forming bacteria and the results suggested that it could effectively inhibit biofilm formation. This preliminary study has proved that AgNPs may be used as antimicrofouling agent for the prevention of biofouling in the early stages.
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Almeida, RBA, G. Akisue, LML Cardoso, JC Junqueira e AO C. Jorge. "Antimicrobial activity of the essential oil of Cymbopogon citratus (DC) Stapf. on Staphylococcus spp., Streptococcus mutans and Candida spp." Revista Brasileira de Plantas Medicinais 15, n. 4 (2013): 474–82. http://dx.doi.org/10.1590/s1516-05722013000400002.
Testo completoAbstract (sommario):
Medicinal plants with fungicide action, antibacterial and anti-inflammatory effects are under investigation. The main purpose of this work was to evaluate the antimicrobial activity of the essential oil from Cymbopogon citratus (DC) Stapf. on strains of Staphylococcus spp., Streptococcus mutans and Candida spp. with planktonic and biofilm growth. To study the micro-organisms in planktonic cells, the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) were determined by using 9 clinical strains for each species and 1 ATCC (American Type Culture Collection) from C. albicans, C. tropicalis, C. glabrata, S. aureus, S. epidermidis and S. mutans. In order to evaluate the effects of the essential oils on biofilms, strains of S. aureus (ATCC 6538), S. mutans (ATCC 35688) and C. albicans (ATCC 18804) were used. The biofilm was formed on acrylic resin discs with isolated micro-organisms or in associations. The number of colony-forming-units (CFU) obtained in each biofilm (CFU/ml) was submitted to Student's t statistical test. The results demonstrated that the essential oil of Cymbopogon citratus showed microbiostatic and microbicidal activity against all tested strains. The average CFU/ml for the biofilm of S. aureus, S. mutans and C. albicans, whether isolated or in association, was lower in the group treated with essential oil than in the control group.
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KİLİC, TUGBA. "Biofilm-Forming Ability and Effect of Sanitation Agents on Biofilm-Control of Thermophile Geobacillus sp. D413 and Geobacillus toebii E134". Polish Journal of Microbiology 69, n. 4 (23 novembre 2020): 411–19. http://dx.doi.org/10.33073/pjm-2020-042.
Testo completoAbstract (sommario):
Geobacillus sp. D413 and Geobacillus toebii E134 are aerobic, non-pathogenic, endospore-forming, obligately thermophilic bacilli. Gram-positive thermophilic bacilli can produce heat-resistant spores. The bacteria are indicator organisms for assessing the manufacturing process’s hygiene and are capable of forming biofilms on surfaces used in industrial sectors. The present study aimed to determine the biofilm-forming properties of Geobacillus isolates and how to eliminate this formation with sanitation agents. According to the results, extracellular DNA (eDNA) was interestingly not affected by the DNase I, RNase A, and proteinase K. However, the genomic DNA (gDNA) was degraded by only DNase I. It seemed that the eDNA had resistance to DNase I when purified. It is considered that the enzymes could not reach the target eDNA. Moreover, the eDNA resistance may result from the conserved folded structure of eDNA after purification. Another assumption is that the eDNA might be protected by other extracellular polymeric substances (EPS) and/or extracellular membrane vesicles (EVs) structures. On the contrary, DNase I reduced unpurified eDNA (mature biofilms). Biofilm formation on surfaces used in industrial areas was investigated in this work: the D413 and E134 isolates adhered to all surfaces. Various sanitation agents could control biofilms of Geobacillus isolates. The best results were provided by nisin for D413 (80%) and α-amylase for E134 (98%). This paper suggests that sanitation agents could be a solution to control biofilm structures of thermophilic bacilli.
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Ameya, Gemechu, Aseer Manilal e Behailu Merdekios. "In vitro Antibacterial Activity and Phytochemical Analysis of Nicotiana tabacum L. Extracted in Different Organic Solvents". Open Microbiology Journal 11, n. 1 (29 dicembre 2017): 352–59. http://dx.doi.org/10.2174/1874285801711010352.
Testo completoAbstract (sommario):
Background: Controlling infectious disease using medicinal plants is the oldest healthcare known to mankind. Regardless of the enormous advances observed in modern medicine, medicinal plants are still playing vital roles. However, only a small proportion of medicinal plants are examined for bioactive compounds which may vary in different factors. This study aimed to evaluate phytochemical constituent and antimicrobial activities of Nicotiana tabacum L. extracted by different solvents against three set of bacteria. Methods: Nicotiana tabacum L. was collected from the Western Ethiopia and extracted in seven organic solvents. An in-vitro anti-bacterial activity of plant extracts was carried out by agar well diffusion assay against microbial type culture collection of human pathogens, clinical bacterial isolates, and biofilm forming bacteria. Gas Chromatographic and Mass Spectroscopic (GC-MS) analysis was used to determine the phytochemical constituents. Results: Antimicrobial activities of plant extract vary by extraction solvents; and ethyl acetate based extracts showed better antimicrobial activities. Of the experimental organisms, biofilm forming uropathogens were the most sensitive while clinical isolates were quite resistant. Analysis of the active ethyl acetate extract by GC-MS evinced a mixture of five volatile compounds; and Pyridine, 3-(1-methyl-2-pyrrolidinyl)-, (S) was the major compound detected. The overall results of the present study revealed that N. tabacum L extract has high antimicrobial activities against biofilm forming uropathogens. Conclusion: High antimicrobial activity was observed in ethyl acetate extract of N. tabacum against the biofilm forming bacteria whereas the clinically isolated bacteria were the most resistant group. The antibacterial property demonstrated could be due to Pyridine, 3-(1-methyl-2-pyrrolidinyl)-(S) with a broad spectrum of activity.
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Tendolkar, Preeti M., Arto S. Baghdayan, Michael S. Gilmore e Nathan Shankar. "Enterococcal Surface Protein, Esp, Enhances Biofilm Formation by Enterococcus faecalis". Infection and Immunity 72, n. 10 (ottobre 2004): 6032–39. http://dx.doi.org/10.1128/iai.72.10.6032-6039.2004.
Testo completoAbstract (sommario):
ABSTRACT Enterococci play a dual role in human ecology. They serve as commensal organisms of the gastrointestinal tract and are also leading causes of multiple antibiotic-resistant hospital-acquired infection. Many nosocomial infections result from the ability of microorganisms to form biofilms. The molecular mechanisms involved in enterococcal biofilm formation are only now beginning to be understood. Enterococcal surface protein, Esp, has been reported to contribute to biofilm formation by Enterococcus faecalis. Recent studies have shown that enterococci form biofilms independently of Esp expression. To precisely determine what role Esp plays in E. faecalis biofilm formation, Esp was expressed on the cell surface of genetically well-defined, natively Esp-deficient strains, and isogenic Esp-positive and Esp-deficient strains were compared for their biofilm-forming ability. The results show that Esp expression leads to a significant increase in biofilm formation, irrespective of the strain tested. The contribution of Esp to biofilm formation was found to be most pronounced in the presence of 0.5% (wt/vol) or greater glucose. These results unambiguously define Esp as a key contributor to the ability of E. faecalis to form biofilms.
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Percival, Steven L., Peter Kite, Kerrie Eastwood, Ricardo Murga, Janice Carr, Matthew J. Arduino e Rodney M. Donlan. "Tetrasodium EDTA as a Novel Central Venous Catheter Lock Solution Against Biofilm". Infection Control & Hospital Epidemiology 26, n. 6 (giugno 2005): 515–19. http://dx.doi.org/10.1086/502577.
Testo completoAbstract (sommario):
AbstractBackground:Central venous catheter (CVC)-related bloodstream infections (BSIs) are known to increase rates of morbidity and mortality in both inpatients and outpatients, including hematology-oncology patients and those undergoing hemodialysis or home infusion therapy. Biofilm-associated organisms on the lumens of these catheters have reduced susceptibility to antimicrobial chemotherapy. This study tested the efficacy of tetrasodium EDTA as a catheter lock solution on biofilms of several clinically relevant microorganisms.Methods:Biofilms ofStaphylococcus epidermidis, methicillin-resistantS. aureus, Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, andCandida albicanswere grown to levels of approximately 1 × 105colony-forming units (CFU)/cm−1on CVC segments in a model system, then subjected to the tetrasodium EDTA lock treatment.Results:Comparisons of biofilms before and after exposure to the 40-mg/mL−1tetrasodium EDTA lock for 21 hours showed that the biofilm viable cell counts of all organisms tested were significantly reduced (P< .05) after exposure to the treatment.Conclusion:Antimicrobial lock treatment using 40 mg/mL−1of tetrasodium EDTA for at least 21 hours could significantly reduce or potentially eradicate CVC-associated bio-films of clinically relevant microorganisms (Infect Control Hosp Epidemiol2005;26:515-519).
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Yoshida, Akihiro, e Howard K. Kuramitsu. "Multiple Streptococcus mutans Genes Are Involved in Biofilm Formation". Applied and Environmental Microbiology 68, n. 12 (dicembre 2002): 6283–91. http://dx.doi.org/10.1128/aem.68.12.6283-6291.2002.
Testo completoAbstract (sommario):
ABSTRACT Streptococcus mutans has been strongly implicated as the principal etiological agent in dental caries. One of the important virulence properties of these organisms is their ability to form biofilms known as dental plaque on tooth surfaces. Since the roles of sucrose and glucosyltransferases in S. mutans biofilm formation have been well documented, we focused our attention on sucrose-independent factors. We have initially identified several mutants that appear to be defective in biofilm formation on abiotic surfaces by an insertional inactivation mutagenesis strategy applied to S. mutans. A total of 27 biofilm-defective mutants were isolated and analyzed in this study. From these mutants, three genes were identified. One of the mutants was defective in the Bacillus subtilis lytR homologue. Another of the biofilm-defective mutants isolated was a yulF homologue, which encodes a hypothetical protein of B. subtilis whose function in biofilm formation is unknown. The vast majority of the mutants were defective in the comB gene required for competence. We therefore have constructed and examined comACDE null mutants. These mutants were also found to be attenuated in biofilm formation. Biofilm formation by several other regulatory gene mutants were also characterized using an in vitro biofilm-forming assay. These results suggest that competence genes as well as the sgp and dgk genes may play important roles in S. mutans biofilm formation.
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Raya, Sunayana, Ankit Belbase, Laxmi Dhakal, Krishna Govinda Prajapati, Reena Baidya e Nabin kishor Bimali. "In-Vitro Biofilm Formation and Antimicrobial Resistance of Escherichia coli in Diabetic and Nondiabetic Patients". BioMed Research International 2019 (19 settembre 2019): 1–8. http://dx.doi.org/10.1155/2019/1474578.
Testo completoAbstract (sommario):
Background. Diabetic patients are more susceptible to urinary tract infection compared to nondiabetic patients, Escherichia coli being the most common uropathogen causing UTI. Unreasonable and incorrect antibiotic prescription for UTI in these patients may induce the development of antibiotic-resistant urinary pathogens resulting in delayed recovery and longer hospitalization. In addition to these, biofilm forming capacity of the pathogen may worsen the problem. The main aim of this cross-sectional study (conducted from March to September 2015) is to detect the biofilm forming capacity of UTI causing micro-organisms and compare the antibiotic resistance pattern of Escherichia coli, the most common cause of UTI, which will help the physician in choosing the best antibiotic. Method. Total of 1,099 clean-catch mid stream urine (CCMSU) was processed by standard microbiological technique; 182 were from the diabetic group and 917 nondiabetic. Following identification, all isolates were subjected to antibiotic susceptibility testing using modified Kirby-Bauer disc diffusion method. In-vitro biofilm forming capacity of the isolates were detected by Microtitre plate method. The data were analyzed using SPSS software 16. Result. Urinary tract infection was found to be significantly higher in diabetic patients (42.9%) compared to nondiabetic patients (17.4%) with Escherichia coli as the most common uropathogen in both diabetic and nondiabetic groups. Similarly, UTI was more common in elderly population (29.5%). Imipenem, nitrofurantoin and amikacin were found to be the most effective drug for uropathogenic E. coli in both diabetic and nondiabetic patients, whereas amoxicillin, ciprofloxacin, and cotrimoxazole were least effective. Of the total bacterial isolates, 43.3% showed positive results for in-vitro biofilm production by the Microtitre plate method. A significantly higher resistance rate was observed among biofilm producing E. coli for quinolones, cotrimoxazole, and third generation cephalosporin ceftriaxone. Most of the biofilm producers (79.5%) were found to be MDR (p-value 0.015). Conclusion. Elderly populations with diabetes are at a higher risk of UTI. Higher biofilm production and resistance to in-use antimicrobial agents in this study render its inefficacy for empirical treatment and point out the importance of biofilm screening to ensure the effective management of infection.
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Tall, B. D., H. N. Williams, K. S. George, R. T. Gray e M. Walch. "Bacterial succession within a biofilm in water supply lines of dental air–water syringes". Canadian Journal of Microbiology 41, n. 7 (1 luglio 1995): 647–54. http://dx.doi.org/10.1139/m95-088.
Testo completoAbstract (sommario):
Biofilms have been implicated as reservoirs for bacterial contamination of water delivered by dental air–water syringes. A 6-month study was done of bacterial colonization and biofilm formation in plastic water supply lines connected to dental air–water syringes. Changes in biofilm flora were observed by both scanning electron microscopy and bacteriologic culture. By day 7, many rod- and spiral-shaped bacteria had colonized the ridged surface of the luminal wall of the tubing, as revealed by scanning electron microscopy. By day 30, individual microcolonies were embedded in extracellular polymeric material. By day 120, these microcolonies had begun to coalesce, and by day 180 the biofilm had developed into a multilayered, heterogenous mixture of microcolonies. The mean aerobic plate counts of colony-forming units of planktonic and biofilm populations were, in log10 values, 5.9 ± 0.54/mL and 4.2 ± 0.82/cm2, respectively. Early colonizers were predominantly Pseudomonas spp., but included Pasteurella, Moraxella, Ochrohactrum, and Aeromonas spp. Flavobacterium and Acinetobacter spp. were observed later. Many of these organisms are opportunistic pathogens. These results demonstrate the longitudinal dynamics of biofilm formation.Key words: dental equipment, air–water syringes, biofilms.
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Larsen, Poul, Jeppe Lund Nielsen, Daniel Otzen e Per Halkjær Nielsen. "Amyloid-Like Adhesins Produced by Floc-Forming and Filamentous Bacteria in Activated Sludge". Applied and Environmental Microbiology 74, n. 5 (11 gennaio 2008): 1517–26. http://dx.doi.org/10.1128/aem.02274-07.
Testo completoAbstract (sommario):
ABSTRACT Amyloid proteins (fimbriae or other microbial surface-associated structures) are expressed by many types of bacteria, not yet identified, in biofilms from various habitats, where they likely are of key importance to biofilm formation and biofilm properties. As these amyloids are potentially of great importance to the floc properties in activated sludge wastewater treatment plants (WWTP), the abundance of amyloid adhesins in activated sludge flocs from different WWTP and the identity of bacteria producing these were investigated. Amyloid adhesins were quantified using a combination of conformationally specific antibodies targeting amyloid fibrils, propidium iodide to target all fixed bacterial cells, confocal laser scanning microscopy, and digital image analysis. The biovolume fraction containing amyloid adhesins ranged from 10 to 40% in activated sludge from 10 different WWTP. The identity of bacteria producing amyloid adhesins was determined using fluorescence in situ hybridization with oligonucleotide probes in combination with antibodies or thioflavin T staining. Among the microcolony-forming bacteria, amyloids were primarily detected among Alpha- and Betaproteobacteria and Actinobacteria. A more detailed analysis revealed that many denitrifiers (from Thauera, Azoarcus, Zoogloea, and Aquaspirillum-related organisms) and Actinobacteria-related polyphosphate-accumulating organisms most likely produced amyloid adhesins, whereas nitrifiers did not. Many filamentous bacteria also expressed amyloid adhesins, including several Alphaproteobacteria (e.g., Meganema perideroedes), some Betaproteobacteria (e.g., Aquaspirillum-related filaments), Gammaproteobacteria (Thiothrix), Bacteroidetes, Chloroflexi (e.g., Eikelboom type 1851), and some foam-forming Actinobacteria (e.g., Gordonia amarae). The results show that amyloid adhesins were an abundant component of activated sludge extracellular polymeric substances and seem to have unexpected, divers functions.
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Song, Bo, Yu-zhen Wang, Guang-yuan Wang, Guang-Lei Liu, Wan-zhong Li e Fang Yan. "The lipopeptide 6-2 produced by Bacillus amyloliquefaciens anti-CA has potent activity against the biofilm-forming organisms". Marine Pollution Bulletin 108, n. 1-2 (luglio 2016): 62–69. http://dx.doi.org/10.1016/j.marpolbul.2016.04.062.
Testo completo
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Ymele-Leki, Patrick, Laetitia Houot e Paula I. Watnick. "Mannitol and the Mannitol-Specific Enzyme IIB Subunit Activate Vibrio cholerae Biofilm Formation". Applied and Environmental Microbiology 79, n. 15 (31 maggio 2013): 4675–83. http://dx.doi.org/10.1128/aem.01184-13.
Testo completoAbstract (sommario):
ABSTRACTVibrio choleraeis a halophilic, Gram-negative rod found in marine environments. Strains that produce cholera toxin cause the diarrheal disease cholera.V. choleraeuse a highly conserved, multicomponent signal transduction cascade known as the phosphoenolpyruvate phosphotransferase system (PTS) to regulate carbohydrate uptake and biofilm formation. Regulation of biofilm formation by the PTS is complex, involving many different regulatory pathways that incorporate distinct PTS components. The PTS consists of the general components enzyme I (EI) and histidine protein (HPr) and carbohydrate-specific enzymes II. Mannitol transport byV. choleraerequires the mannitol-specific EII (EIIMtl), which is expressed only in the presence of mannitol. Here we show that mannitol activatesV. choleraebiofilm formation and transcription of thevpsbiofilm matrix exopolysaccharide synthesis genes. This regulation is dependent on mannitol transport. However, we show that, in the absence of mannitol, ectopic expression of the B subunit of EIIMtlis sufficient to activate biofilm accumulation. Mannitol, a common compatible solute and osmoprotectant of marine organisms, is a main photosynthetic product of many algae and is secreted by algal mats. We propose that the ability ofV. choleraeto respond to environmental mannitol by forming a biofilm may play an important role in habitat selection.
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Rath, Shakti, Sourav Chandra Bidyasagar Bal e Debasmita Dubey. "Oral Biofilm: Development Mechanism, Multidrug Resistance, and Their Effective Management with Novel Techniques". Rambam Maimonides Medical Journal 12, n. 1 (19 gennaio 2021): e0004. http://dx.doi.org/10.5041/rmmj.10428.
Testo completoAbstract (sommario):
Biofilms are formed by the congregation of one or more types of microorganisms that can grow on a firm surface. Dental plaque is one of the most commonly forming biofilms in the oral cavity and appears as a slimy layer on the surface of the teeth. In general, the formation is slow, but biofilms are very adaptive to the changing environment, and a mature biofilm can cause many health-related problems in humans. These biofilms remain unaffected by antibiotics as they do not allow the penetration of antibiotics. Moreover, the increased level of virulence and antibiotic resistance of microorganisms in the oral biofilm or dental plaque has made its clinical management a serious clinical challenge worldwide. Chlorhexidine-like antimicrobial drugs have been partially effective in removing such organisms; however, the precise and continuous elimination of these microorganisms without disturbing the normal microbial flora of the oral cavity is still a challenge. This paper focuses on the process of oral biofilm formation, related complications, development of drug-resistant bacteria in these biofilms, and their effective management by the use of different novel techniques.
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Malic, Sladjana, Katja E. Hill, Anthony Hayes, Steven L. Percival, David W. Thomas e David W. Williams. "Detection and identification of specific bacteria in wound biofilms using peptide nucleic acid fluorescent in situ hybridization (PNA FISH)". Microbiology 155, n. 8 (1 agosto 2009): 2603–11. http://dx.doi.org/10.1099/mic.0.028712-0.
Testo completoAbstract (sommario):
Biofilms provide a reservoir of potentially infectious micro-organisms that are resistant to antimicrobial agents, and their importance in the failure of medical devices and chronic inflammatory conditions is increasingly being recognized. Particular research interest exists in the association of biofilms with wound infection and non-healing, i.e. chronic wounds. In this study, fluorescent in situ hybridization (FISH) was used in combination with confocal laser scanning microscopy (CLSM) to detect and characterize the spatial distribution of biofilm-forming bacteria which predominate within human chronic skin wounds (Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus sp. and Micrococcus sp.). In vitro biofilms were prepared using a constant-depth film fermenter and a reconstituted human epidermis model. In vivo biofilms were also studied using biopsy samples from non-infected chronic venous leg ulcers. The specificity of peptide nucleic acid (PNA) probes for the target organisms was confirmed using mixed preparations of planktonic bacteria and multiplex PNA probing. Identification and location of individual bacterial species within multi-species biofilms demonstrated that P. aeruginosa was predominant. CLSM revealed clustering of individual species within mixed-species biofilms. FISH analysis of archive chronic wound biopsy sections showed bacterial presence and allowed bacterial load to be determined. The application of this standardized procedure makes available an assay for identification of single- or multi-species bacterial populations in tissue biopsies. The technique provides a reliable tool to study bacterial biofilm formation and offers an approach to assess targeted biofilm disruption strategies in vivo.
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Williams, Henry N., Jacqueline I. Kelley, Marcie L. Baer e Been-Foo Turng. "The association of bdellovibrios with surfaces in the aquatic environment". Canadian Journal of Microbiology 41, n. 12 (1 dicembre 1995): 1142–47. http://dx.doi.org/10.1139/m95-159.
Testo completoAbstract (sommario):
In the aquatic environment, the association of microorganisms with surfaces represents an important phase in the life cycle and ecology of many microbial species. However, previous studies to understand the ecology of the bdellovibrios have ignored examination of the role of surfaces and surface association. In this report, the association of bdellovibrios with sterile surfaces and the stability of the organisms on abiotic and biotic surfaces were investigated. Sterilized oyster shells, glass slides, and steel and titanium surfaces were submerged in the Patuxent River. Following submersion for periods ranging from 2 h to 1 week, test surfaces were scraped or brushed to remove adherent biofilm surface material. The resulting suspension of surface biofilm was cultured for total numbers of bacterial colony-forming units and bdellovibrio plaque-forming units. In other experiments on the persistence of bdellovibrios on surfaces, mussel shells and tunicates with accumulated biofilm were exposed to repeated treatments of mechanical agitation. Following each treatment, the suspension supernatant was cultured for the numbers of predators released from the surface. The results of the two investigations revealed that bdellovibrios associate with surfaces following brief periods of submersion in natural waters, the type of surface influences the association, the number of the predators recovered increased with the time of submersion to a certain peak, and the predators on surfaces are relatively resistant to removal by physical agitation of the surrounding water.Key words: bdellovibrio, surface association.
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Piehl, Emily C., Kathryn E. Daffinee e Kerry LaPlante. "1323. Substantial Doses of Daptomycin and Rifampin Eradicate S. epidermidis Biofilm in an In Vitro Pharmacodynamic (IVPD) Model". Open Forum Infectious Diseases 7, Supplement_1 (1 ottobre 2020): S672—S673. http://dx.doi.org/10.1093/ofid/ofaa439.1505.
Testo completoAbstract (sommario):
Abstract Background The concentration of antibiotics at the site of action needed to eradicate biofilm is currently unknown. Studies have previously suggested that bacteria in biofilms are 1000-fold more resistant to antibiotics than free-floating planktonic bacteria. We sought to describe concentrations of daptomycin alone and in combination with rifampin in relation to the pharmacodynamic exposures for biofilm eradication. Methods We utilized a methicillin-resistant high biofilm-forming S. epidermidis strain RP62a (ATCC® 35984) over a 48-hour in vitro PD biofilm model. The Centers for Disease Control (CDC) Biofilm Reactor model was used with chromium cobalt materials to simulate an orthopedic device infection. The reactor was inoculated and underwent a 24-hr growth phase and 16-hr conditioning phase to form biofilm on the chromium cobalt coupons, and then a 48-hr PK-PD phase was run. The daptomycin MIC for RP62a was 0.5 mg/L and the rifampin MIC was 0.015 mg/L. We modeled a growth control of the isolate alone, a 12 mg/kg regimen of daptomycin (fCmax: 14.7 mg/L, Ke 0.09), a daptomycin concentration of 1000 mg/L (2000x MIC), and a combination model of daptomycin 1000 mg/L with rifampin 15 mg/L (1000x MIC). Coupons with bacteria embedded in biofilm were sonicated, vortexed, and plated on Tryptic Soy Agar for colony counts read at 24 hrs. Bactericidal activity was defined as ≥ 3-log10 CFU/mL reduction from the initial inoculum. Results The simulated humanized dosing regimen of daptomycin 12 mg/kg (fAUC0-24/MIC: 204) was similar to the growth control model. Bactericidal kill was demonstrated at 24hr and 48hr in the daptomycin 1000 mg/L model (fAUC0-24/MIC: 20,248) but did not fall beneath the limit of detection. The daptomycin and rifampin combination model demonstrated bactericidal kill at 24hr and 48hr and went below the limit of detection. Conclusion This study demonstrated that significantly higher concentrations of antibiotics are needed at the site of action to eradicate biofilm than what maximum systemic dosing can provide. Identifying these concentrations provides a foundation for localized antibiotic therapy and further studies are needed to elucidate these concentrations for a variety of antibiotics and biofilm-forming organisms. Disclosures Kerry LaPlante, PharmD, Merck (Advisor or Review Panel member, Research Grant or Support)Ocean Spray Cranberries, Inc. (Research Grant or Support)Pfizer Pharmaceuticals (Research Grant or Support)Shionogi, Inc. (Research Grant or Support)
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Fei, Chenyi, Sheng Mao, Jing Yan, Ricard Alert, Howard A. Stone, Bonnie L. Bassler, Ned S. Wingreen e Andrej Košmrlj. "Nonuniform growth and surface friction determine bacterial biofilm morphology on soft substrates". Proceedings of the National Academy of Sciences 117, n. 14 (19 marzo 2020): 7622–32. http://dx.doi.org/10.1073/pnas.1919607117.
Testo completoAbstract (sommario):
During development, organisms acquire three-dimensional (3D) shapes with important physiological consequences. While basic mechanisms underlying morphogenesis are known in eukaryotes, it is often difficult to manipulate them in vivo. To circumvent this issue, here we present a study of developingVibrio choleraebiofilms grown on agar substrates in which the spatiotemporal morphological patterns were altered by varying the agar concentration. Expanding biofilms are initially flat but later undergo a mechanical instability and become wrinkled. To gain mechanistic insights into this dynamic pattern-formation process, we developed a model that considers diffusion of nutrients and their uptake by bacteria, bacterial growth/biofilm matrix production, mechanical deformation of both the biofilm and the substrate, and the friction between them. Our model shows quantitative agreement with experimental measurements of biofilm expansion dynamics, and it accurately predicts two distinct spatiotemporal patterns observed in the experiments—the wrinkles initially appear either in the peripheral region and propagate inward (soft substrate/low friction) or in the central region and propagate outward (stiff substrate/high friction). Our results, which establish that nonuniform growth and friction are fundamental determinants of stress anisotropy and hence biofilm morphology, are broadly applicable to bacterial biofilms with similar morphologies and also provide insight into how other bacterial biofilms form distinct wrinkle patterns. We discuss the implications of forming undulated biofilm morphologies, which may enhance the availability of nutrients and signaling molecules and serve as a “bet hedging” strategy.
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Motegi, Mizuho, Yuzo Takagi, Hideo Yonezawa, Nobuhiro Hanada, Jun Terajima, Haruo Watanabe e Hidenobu Senpuku. "Assessment of Genes Associated with Streptococcus mutans Biofilm Morphology". Applied and Environmental Microbiology 72, n. 9 (settembre 2006): 6277–87. http://dx.doi.org/10.1128/aem.00614-06.
Testo completoAbstract (sommario):
ABSTRACT Streptococcus mutans, the major pathogen responsible for dental caries in humans, is a biofilm-forming bacterium. In the present study, 17 different pulsed-field gel electrophoresis patterns of genomic DNA were identified in S. mutans organisms isolated clinically from whole saliva. The S. mutans isolates showed different abilities to form biofilms on polystyrene surfaces in semidefined minimal medium cultures. Following cultivation in a flow cell system in tryptic soy broth with 0.25% sucrose and staining using a BacLight LIVE/DEAD system, two strains, designated FSC-3 and FSC-4, showed the greatest and least, respectively, levels of biofilm formation when examined with confocal laser scanning microscopy. Further, image analyses of spatial distribution and architecture were performed to quantify the merged green (live cells) and red (dead cells) light. The light intensity of the FSC-3 biofilm was greater than that of the FSC-4 biofilm in the bottom area but not in the top area. S. mutans whole-genome array results showed that approximately 3.8% of the genes were differentially expressed in the two strains, of which approximately 2.2%, including bacitracin transport ATP-binding protein gene glrA and a BLpL-like putative immunity protein gene, were activated in FSC-3. In addition, about 1.6% of the genes, including those associated with phosphotransferase system genes, were repressed. Analyses of the glrA-deficient strains and reverse transcription-PCR confirmed the role of the gene in biofilm formation. Differential assessment of biofilm-associated genes in clinical strains may provide useful information for understanding the morphological development of streptococcal biofilm, as well as for colonization of S. mutans.
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Nuryastuti, Titik, Ning Rintiswati e Praseno Praseno. "STUDI PENDAHULUAN NONTUBERCULOUS MYCOBACTERIA (NTM): PEMBENTUKAN BIOFILM, MOTILITAS GESER, DAN POLA KEPEKAAN ANTIBIOTIK". Mandala Of Health 11, n. 1 (17 ottobre 2018): 9. http://dx.doi.org/10.20884/1.mandala.2018.11.1.570.
Testo completoAbstract (sommario):
Nontuberculous mycobacteria (NTM) adalah mikrorganisme yang banyak dijumpai di lingkungan, namun, baru-baru ini dianggap patogen karena kejadian infeksinya meningkat secara signifikan. Penelitian ini bertujuan untuk mengetahui kemampuan pembentukan biofilm isolat NTM, korelasinya dengan sifat motilitas geser, dan untuk menganalisis pola kepekaan antibiotik. Strain NTM yang dipakai dalam penelitian ini adalah 10 isolat klinis NTM yang diperoleh dari laboratorium TB, Departemen Mikrobiologi, Fakultas Kedokteran UGM Yogyakarta. Kemampuan pembentukan biofilm dideteksi dengan menggunakan uji mikrotiter dan pewarnaan dengan kristal violet 1%. Uji motilitas geser dilakukan pada medium motilitas, terdiri dari 0,3% Middlebrook 7H9-agar tanpa suplemen. Pola kepekaan antibiotik diteliti dengan teknik dilusi sesuai metode CLSI. Dari penelitian ini menunjukkan bahwa 7 dari 10 isolat NTM merupakan penghasil biofilm kuat, sementara 1 isolat sebagai strain penghasil biofilm moderat, dan 2 isolat tidak menghasilkan biofilm. Sementara itu, strain pembentuk biofilm mampu melakukan motilitas geser pada agar semisolid, dan 2 isolat NTM yang tidak memiliki kemampuan pembentukan biofilm tidak dapat melakukan motilitas geser. Sifat pembentukan biofilm berkorelasi dengan kemampuan isolat NTM untuk melakukan motilitas geser pada media agar semisolid. Klaritromisin merupakan antibiotik yang paling efektif terhadap isolat NTM yang diuji (poten terhadap 50% isolat uji), diikuti oleh gentamisin (40%), sedangkan kanamisin, levofloxacin, dan ofloxacin menunjukkan tingkat potensi yang sama (30%). Ceftriaxone hanya mampu menghambat pertumbuhan isolat NTM sekitar 20%. Selanjutnya, kotrimoksazol dan amoksisilin memiliki aktivitas in vitro yang buruk terhadap isolat NTM karena tidak ada isolat NTM yang sensitif terhadap kedua antibiotik ini.
Nontuberculous mycobacteria (NTM) are ubiquitous organisms commonly found in the environment. However, recently it is considered as emerging global interest since the incidence increase significantly. This study aimed to investigate the biofilm forming ability of NTM isolates, correlated with the sliding motility properties, and to analyze their antibiotic susceptibility pattern. NTM strain included in this study were 10 NTM clinical isolates obtained from TB laboratory, Microbiology Departement, Faculty of Medicine UGM Yogyakarta. Biofilm forming capability was detected by using biofilm development assay in microtiter plate and staining with 1% crystal violet. Sliding motility assay was performed on motility medium, consisting of Middlebrook 7H9- 0.3% agar without supplements. Antibiotic susceptibility pattern was investigated by macrobroth dilution technique according to CLSI methods. Our study revealed that 7 out of 10 NTM isolates produced biofilm strongly, while 1 isolate demontrated as moderate biofilm former strain, and the remaining 2 isolates did not produce biofilm on polysterene substrate. Meanwhile, biofilm-former strain are able to slide on semisolid agar, and 2 non-adherent NTM isolates did not have ability to perform sliding motility. A good correlation was found between mycobacterial sliding and biofilm assembly of NTM isolates. Clarithromycin has been shown as the most effective antibiotic against NTM isolates tested, which was active against 50% of all isolates, followed by gentamycin (40%), while kanamycin, levofloxacin, and ofloxacin showed the same level of potency (30%). Ceftriaxone was only able to inhibit the growth of NTM isolates about 20%. Furthermore, cotrimoxazole and amoxicillin had poor in vitro activity against NTM species.
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Greer, Helen, Kanesha Overton, Megan Ferguson, Eileen Spain, Louise Darling, Megan Núñez e Catherine Volle. "Extracellular Polymeric Substance Protects Some Cells in an Escherichia coli Biofilm from the Biomechanical Consequences of Treatment with Magainin 2". Microorganisms 9, n. 5 (30 aprile 2021): 976. http://dx.doi.org/10.3390/microorganisms9050976.
Testo completoAbstract (sommario):
Bacterial biofilms have long been recognized as a source of persistent infections and industrial contamination with their intransigence generally attributed to their protective layer of extracellular polymeric substances (EPS). EPS, consisting of secreted nucleic acids, proteins, and polysaccharides, make it difficult to fully eliminate biofilms by conventional chemical or physical means. Since most bacteria are capable of forming biofilms, understanding how biofilms respond to new antibiotic compounds and components of the immune system has important ramifications. Antimicrobial peptides (AMPs) are both potential novel antibiotic compounds and part of the immune response in many different organisms. Here, we use atomic force microscopy to investigate the biomechanical changes that occur in individual cells when a biofilm is exposed to the AMP magainin 2 (MAG2), which acts by permeabilizing bacterial membranes. While MAG2 is able to prevent biofilm initiation, cells in an established biofilm can withstand exposure to high concentrations of MAG2. Treated cells in the biofilm are classified into two distinct populations after treatment: one population of cells is indistinguishable from untreated cells, maintaining cellular turgor pressure and a smooth outer surface, and the second population of cells are softer than untreated cells and have a rough outer surface after treatment. Notably, the latter population is similar to planktonic cells treated with MAG2. The EPS likely reduces the local MAG2 concentration around the stiffer cells since once the EPS was enzymatically removed, all cells became softer and had rough outer surfaces. Thus, while MAG2 appears to have the same mechanism of action in biofilm cells as in planktonic ones, MAG2 cannot eradicate a biofilm unless coupled with the removal of the EPS.
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Walsh, Thomas J., Robert Schlegel, Marcia M. Moody, John W. Costerton e Michael Salcman. "Ventriculoatrial Shunt Infection Due to Cryptococcus neoformans: An Ultrastructural and Quantitative Microbiological Study". Neurosurgery 18, n. 3 (1 marzo 1986): 376–82. http://dx.doi.org/10.1227/00006123-198603000-00025.
Testo completoAbstract (sommario):
Abstract A 28-year-old man presented with hydrocephalus due to an infection by Cryptococcus neoformans involving his ventriculoatrial shunt. Ultrastructural studies of the ventriculoatrial shunt demonstrated yeastlike organisms consistent with C. neoformans within a biofilm on the appliance. Quantitative microbiological studies of segments of the shunt demonstrated C. neoformans in a concentration gradient from 9 × 106 colony-forming units (CFU)/0.5-cm section involving the ventricular portion of the catheter to 1 × 102 CFU/0.5-cm section at the vascular tip. The clinical, microbiological, and ultrastructural data suggest that this cryptococcal infection started as a ventriculitis or encephalitis with extension to the meningeal surface. Future application of these methods may further elucidate the pathogenesis of ventriculoatrial shunt infections.
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Kerekes, E. B., É. Deák, M. Takó, R. Tserennadmid, T. Petkovits, C. Vágvölgyi e J. Krisch. "Anti-biofilm forming and anti-quorum sensing activity of selected essential oils and their main components on food-related micro-organisms". Journal of Applied Microbiology 115, n. 4 (10 luglio 2013): 933–42. http://dx.doi.org/10.1111/jam.12289.
Testo completo
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Bajracharya, Suman, Karolien Vanbroekhoven, Cees J. N. Buisman, David P. B. T. B. Strik e Deepak Pant. "Bioelectrochemical conversion of CO2 to chemicals: CO2 as a next generation feedstock for electricity-driven bioproduction in batch and continuous modes". Faraday Discussions 202 (2017): 433–49. http://dx.doi.org/10.1039/c7fd00050b.
Testo completoAbstract (sommario):
The recent concept of microbial electrosynthesis (MES) has evolved as an electricity-driven production technology for chemicals from low-value carbon dioxide (CO2) using micro-organisms as biocatalysts. MES from CO2 comprises bioelectrochemical reduction of CO2 to multi-carbon organic compounds using the reducing equivalents produced at the electrically-polarized cathode. The use of CO2 as a feedstock for chemicals is gaining much attention, since CO2 is abundantly available and its use is independent of the food supply chain. MES based on CO2 reduction produces acetate as a primary product. In order to elucidate the performance of the bioelectrochemical CO2 reduction process using different operation modes (batch vs. continuous), an investigation was carried out using a MES system with a flow-through biocathode supplied with 20 : 80 (v/v) or 80 : 20 (v/v) CO2 : N2 gas. The highest acetate production rate of 149 mg L−1 d−1 was observed with a 3.1 V applied cell-voltage under batch mode. While running in continuous mode, high acetate production was achieved with a maximum rate of 100 mg L−1 d−1. In the continuous mode, the acetate production was not sustained over long-term operation, likely due to insufficient microbial biocatalyst retention within the biocathode compartment (i.e. suspended micro-organisms were washed out of the system). Restarting batch mode operations resulted in a renewed production of acetate. This showed an apparent domination of suspended biocatalysts over the attached (biofilm forming) biocatalysts. Long term CO2 reduction at the biocathode resulted in the accumulation of acetate, and more reduced compounds like ethanol and butyrate were also formed. Improvements in the production rate and different biomass retention strategies (e.g. selecting for biofilm forming micro-organisms) should be investigated to enable continuous biochemical production from CO2 using MES. Certainly, other process optimizations will be required to establish MES as an innovative sustainable technology for manufacturing biochemicals from CO2 as a next generation feedstock.
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Rao, Dhana, Jeremy S. Webb e Staffan Kjelleberg. "Competitive Interactions in Mixed-Species Biofilms Containing the Marine Bacterium Pseudoalteromonas tunicata". Applied and Environmental Microbiology 71, n. 4 (aprile 2005): 1729–36. http://dx.doi.org/10.1128/aem.71.4.1729-1736.2005.
Testo completoAbstract (sommario):
ABSTRACT Pseudoalteromonas tunicata is a biofilm-forming marine bacterium that is often found in association with the surface of eukaryotic organisms. It produces a range of extracellular inhibitory compounds, including an antibacterial protein (AlpP) thought to be beneficial for P. tunicata during competition for space and nutrients on surfaces. As part of our studies on the interactions between P. tunicata and the epiphytic bacterial community on the marine plant Ulva lactuca, we investigated the hypothesis that P. tunicata is a superior competitor compared with other bacteria isolated from the plant. A number of U. lactuca bacterial isolates were (i) identified by 16S rRNA gene sequencing, (ii) characterized for the production of or sensitivity to extracellular antibacterial proteins, and (iii) labeled with a fluorescent color tag (either the red fluorescent protein DsRed or green fluorescent protein). We then grew single- and mixed-species bacterial biofilms containing P. tunicata in glass flow cell reactors. In pure culture, all the marine isolates formed biofilms containing microcolony structures within 72 h. However, in mixed-species biofilms, P. tunicata removed the competing strain unless its competitor was relatively insensitive to AlpP (Pseudoalteromonas gracilis) or produced strong inhibitory activity against P. tunicata (Roseobacter gallaeciensis). Moreover, biofilm studies conducted with an AlpP− mutant of P. tunicata indicated that the mutant was less competitive when it was introduced into preestablished biofilms, suggesting that AlpP has a role during competitive biofilm formation. When single-species biofilms were allowed to form microcolonies before the introduction of a competitor, these microcolonies coexisted with P. tunicata for extended periods of time before they were removed. Two marine bacteria (R. gallaeciensis and P. tunicata) were superior competitors in this study. Our data suggest that this dominance can be attributed to the ability of these organisms to rapidly form microcolonies and their ability to produce extracellular antibacterial compounds.
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Singh, Rachna, Pallab Ray, Anindita Das e Meera Sharma. "Role of persisters and small-colony variants in antibiotic resistance of planktonic and biofilm-associated Staphylococcus aureus: an in vitro study". Journal of Medical Microbiology 58, n. 8 (1 agosto 2009): 1067–73. http://dx.doi.org/10.1099/jmm.0.009720-0.
Testo completoAbstract (sommario):
The presence of persister cells and small-colony variants (SCVs) has been associated with enhanced antibiotic resistance of many organisms in biofilms. This study investigated whether persisters and/or SCVs contribute to the antibiotic resistance of Staphylococcus aureus biofilms. A detailed dose-dependent killing of biofilms and planktonic cells with five antibiotics (oxacillin, cefotaxime, amikacin, ciprofloxacin and vancomycin) was analysed by treating them with each antibiotic at a concentration of 0–100 μg ml−1 at 37 °C for 48 h. The killing of biofilm cells by all of the antibiotics showed the presence of persister cells – most cells in the population died, leaving a fraction that persisted, even at higher concentrations of the antibiotics. These persisters represented a transient resistant phenotype and reverted to a killing curve resembling that of the wild-type parent upon re-exposure to the antibiotics. SCVs were observed in biofilms only after treatment with ciprofloxacin, and these SCVs were of a transient nature. The treatment of planktonic cells with oxacillin, cefotaxime, ciprofloxacin and vancomycin killed the entire population and no persisters were detected. Transient SCVs, observed in planktonic cells following exposure to these antibiotics, were killed at higher antibiotic concentrations. The treatment of planktonic cells with amikacin yielded a small subpopulation of survivors that included persisters (at numbers significantly lower than for the biofilms) and highly resistant, stable SCVs with an increased biofilm-forming capacity in comparison with the wild-type parent. Thus the high resistance of S. aureus biofilms to multiple unrelated antibiotics is largely dependent on the presence of persister cells. Biofilms harbour a large number of persisters in comparison with planktonic cultures, which either do not harbour persisters or harbour only a small number. SCVs, although not specifically associated with S. aureus biofilms, have an increased biofilm-forming capacity and this may explain the frequent isolation of SCVs from biofilm-associated infections. The intrinsic resistance of these variants may in turn contribute to the enhanced antibiotic resistance of the biofilms thus formed.
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Zhao, Yu, Martien P. M. Caspers, Karin I. Metselaar, Paulo de Boer, Guus Roeselers, Roy Moezelaar, Masja Nierop Groot, Roy C. Montijn, Tjakko Abee e Remco Kort. "Abiotic and Microbiotic Factors Controlling Biofilm Formation by Thermophilic Sporeformers". Applied and Environmental Microbiology 79, n. 18 (12 luglio 2013): 5652–60. http://dx.doi.org/10.1128/aem.00949-13.
Testo completoAbstract (sommario):
ABSTRACTOne of the major concerns in the production of dairy concentrates is the risk of contamination by heat-resistant spores from thermophilic bacteria. In order to acquire more insight in the composition of microbial communities occurring in the dairy concentrate industry, a bar-coded 16S amplicon sequencing analysis was carried out on milk, final products, and fouling samples taken from dairy concentrate production lines. The analysis of these samples revealed the presence of DNA from a broad range of bacterial taxa, including a majority of mesophiles and a minority of (thermophilic) spore-forming bacteria. Enrichments of fouling samples at 55°C showed the accumulation of predominantlyBrevibacillusandBacillus, whereas enrichments at 65°C led to the accumulation ofAnoxybacillusandGeobacillusspecies. Bacterial population analysis of biofilms grown using fouling samples as an inoculum indicated that bothAnoxybacillusandGeobacilluspreferentially form biofilms on surfaces at air-liquid interfaces rather than on submerged surfaces. Three of the most potent biofilm-forming strains isolated from the dairy factory industrial samples, includingGeobacillus thermoglucosidans,Geobacillus stearothermophilus, andAnoxybacillus flavithermus, have been characterized in detail with respect to their growth conditions and spore resistance. Strikingly,Geobacillus thermoglucosidans, which forms the most thermostable spores of these three species, is not able to grow in dairy intermediates as a pure culture but appears to be dependent for growth on other spoilage organisms present, probably as a result of their proteolytic activity. These results underscore the importance of abiotic and microbiotic factors in niche colonization in dairy factories, where the presence of thermophilic sporeformers can affect the quality of end products.
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Fuentes, Elsa, Rafael Carballeira e Beatriz Prieto. "Role of Exposure on the Microbial Consortiums on Historical Rural Granite Buildings". Applied Sciences 11, n. 9 (22 aprile 2021): 3786. http://dx.doi.org/10.3390/app11093786.
Testo completoAbstract (sommario):
Local granite has been used throughout history in Galicia (NW Spain), forming the basis of much of the region’s architecture. Like any other rock, granite provides an ecological niche for a multitude of organisms that form biofilms that can affect the physical integrity of the stone. In this study, for the first time, characterization of the microbial consortium forming biofilms that developed on historical rural granite buildings is carried out using a combination of culture-dependent and next generation sequencing (NGS) techniques. Results pointed to differences in biofilm composition on the studied rural granite buildings and that of previously analyzed urban granite buildings, especially in terms of abundance of cyanobacteria and lichenized fungi. Exposure was corroborated as an important factor, controlling both the diversity and abundance of microorganisms on walls, with environmental factors associated with a northern orientation favoring a higher diversity of fungi and green algae, and environmental factors associated with the west orientation determining the abundance of lichenized fungi. The orientation also affected the distribution of green algae, with one of the two most abundant species, Trentepohlia cf. umbrina, colonizing north-facing walls, while the other, Desmococcus olivaceus, predominated on west-facing walls.
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Bamunuarachchi, Nilushi I., Fazlurrahman Khan e Young-Mog Kim. "Bactericidal Activity of Sargassum aquifolium (Turner) C. Agardh against Gram-positive and Gram-negative Biofilm-forming Pathogenic Bacteria". Current Pharmaceutical Biotechnology 22, n. 12 (2 settembre 2021): 1628–40. http://dx.doi.org/10.2174/1389201022666210111122230.
Testo completoAbstract (sommario):
Aim: To study the bactericidal activity of crude ethanolic extract and fractionations obtained from Sargassum aquifolium (Turner) C. Agardh (brown algae) towards Gram-positive bacteria and Gram-negative biofilm-forming human pathogenic bacteria. Background: The increasing emergence of antibiotic-resistant bacteria in the hospital and community settings has led to the discovery of alternative strategies. Marine organisms are considered as one of the potential sources of diverse bioactive molecules against several biological activities. Hence, the algae, especially the marine brown algae were selected to evaluate its antibacterial activities towards biofilm-forming human pathogenic bacteria. Objective: To restrain the drug-resistant ability of pathogenic bacteria, we checked the extract of Sargassum aquifolium (Turner) C. Agardh (Phyophyceae) for the concerned bioactive compounds. Methods: Antibacterial activity towards both Gram-positive and Gram-negative bacteria was evaluated using disk diffusion and broth microdilution assays. Furthermore, the active compound present in the extracts was also identified using Gas-Chromatography-Mass Spectroscopy (GC-MS). Results: A total of 21 bioactive compounds were identified using GC-MS analysis with different chemical natures. The crude ethanolic extraction was fractionated sequentially according to the eluotropic series from less to extreme polar. The highest zone of inhibition was recorded for ethanolic extract on Listeria monocytogenes with a value of 38.00±0.17 mm and the lowest was 10.67±0.06 mm for ethyl acetate fraction on Pseudomonas aeruginosa. Ethyl acetate fractionate showed a higher effectivity than other fractionations. An MIC value of 256 μg/mL was recorded against Staphylococcus aureus and L. monocytogenes and 512 μg/mL against Escherichia coli and P. aeruginosa. Its ethanolic extract also showed synergism with oxytetracycline on S. aureus, L. monocytogenes, and E. coli. Furthermore, the same extracts also showed synergism with tetracycline on E. coli and with erythromycin on P. aeruginosa. Conclusion: The present study reports the antibacterial activity of the S. aquifolium (Turner) C. Agardh extracts against human pathogenic bacteria. Furthermore, it also predicts the synergistic activity of selected antibiotic combinations against both selected Gram-positive and Gram-negative pathogenic bacteria.
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Rao, Dhana, Jeremy S. Webb e Staffan Kjelleberg. "Microbial Colonization and Competition on the Marine Alga Ulva australis". Applied and Environmental Microbiology 72, n. 8 (agosto 2006): 5547–55. http://dx.doi.org/10.1128/aem.00449-06.
Testo completoAbstract (sommario):
ABSTRACT Pseudalteromonas tunicata and Roseobacter gallaeciensis are biofilm-forming marine bacteria that are often found in association with the surface of the green alga Ulva australis. They are thought to benefit the plant host by producing inhibitory compounds that are active against common fouling organisms. We investigated factors that influence the ability of P. tunicata and R. gallaeciensis to attach to and colonize the plant surface and also the competitive interactions that occur between these organisms and other isolates from U. australis during biofilm formation on the plant surface. A surprisingly high number of P. tunicata cells, at least 108 cells ml−1, were required for colonization and establishment of a population of cells that persists on axenic surfaces of U. australis. Factors that enhanced colonization of P. tunicata included inoculation in the dark and pregrowth of inocula in medium containing cellobiose as the sole carbon source (cellulose is a major surface polymer of U. australis). It was also found that P. tunicata requires the presence of a mixed microbial community to colonize effectively. In contrast, R. gallaeciensis effectively colonized the plant surface under all conditions tested. Studies of competitive interactions on the plant surface revealed that P. tunicata was numerically dominant compared with all other bacterial isolates tested (except R. gallaeciensis), and this dominance was linked to production of the antibacterial protein AlpP. Generally, P. tunicata was able to coexist with competing strains, and each strain existed as microcolonies in spatially segregated regions of the plant. R. gallaeciensis was numerically dominant compared with all strains tested and was able to invade and disperse preestablished biofilms. This study highlighted the fact that microbial colonization of U. australis surfaces is a dynamic process and demonstrated the differences in colonization strategies exhibited by the epiphytic bacteria P. tunicata and R. gallaeciensis.
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Doghri, Ibtissem, Florence Brian-Jaisson, Marianne Graber, Alexis Bazire, Alain Dufour, Marie-Noëlle Bellon-Fontaine, Jean-Marie Herry et al. "Antibiofilm activity in the culture supernatant of a marine Pseudomonas sp. bacterium". Microbiology 166, n. 3 (1 marzo 2020): 239–52. http://dx.doi.org/10.1099/mic.0.000878.
Testo completoAbstract (sommario):
In the marine environment, most solid surfaces are covered by microbial biofilms, mainly composed of bacteria and diatoms. The negative effects of biofilms on materials and equipment are numerous and pose a major problem for industry and human activities. Since marine micro-organisms are an important source of bioactive metabolites, it is possible that they synthesize natural ecofriendly molecules that inhibit the adhesion of organisms. In this work, the antibiofilm potential of marine bacteria was investigated using Flavobacterium sp. II2003 as a target. This strain is potentially a pioneer strain of bacteria that was previously selected from marine biofilms for its strong biofilm-forming ability. The culture supernatants of 86 marine heterotrophic bacteria were tested for their ability to inhibit Flavobacterium sp. II2003 biofilm formation and the Pseudomonas sp. IV2006 strain was identified as producing a strong antibiofilm activity. The Pseudomonas sp. IV2006 culture supernatant (SNIV2006) inhibited Flavobacterium sp. II2003 adhesion without killing the bacteria or inhibiting its growth. Moreover, SNIV2006 had no effect on the Flavobacterium sp. II2003 cell surface hydrophilic/hydrophobic and general Lewis acid–base characteristics, but modified the surface properties of glass, making it on the whole more hydrophilic and more alkaline and significantly reducing bacterial cell adhesion. The glass-coating molecules produced by Pseudomonas sp. IV2006 were found to probably be polysaccharides, whereas the antibiofilm molecules contained in SNIV2006 and acting during the 2 h adhesion step on glass and polystyrene surfaces would be proteinaceous. Finally, SNIV2006 exhibited a broad spectrum of antibiofilm activity on other marine bacteria such as Flavobacterium species that are pathogenic for fish, and human pathogens in both the medical environment, such as Staphylococcus aureus and Pseudomonas aeruginosa , and in the food industry, such as Yersinia enterocolitica . Thus, a wide range of applications could be envisaged for the SNIV2006 compounds, both in aquaculture and human health.