Academic literature on the topic 'Bacterii'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Bacterii.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Journal articles on the topic "Bacterii"
1
Vasile, TODIRAȘ, MELNIC Maria, PRISACARI Svetlana, LUNGU Angela, RUSU Ștefan, and ERHAN Dumitru. "BACTERII SIMBIOTROF-FIXATOARE DE AZOT CU DIVERSE ÎNSUȘIRI." STUDIA UNIVERSITATIS MOLDAVIAE Științe Reale și ale Naturii, no. 6(146) (2021): 49–53. https://doi.org/10.5281/zenodo.5681336.
Full textAbstract:
A fost studiat efectul stimulator al bacteriilor de nodozități din genul <em>Rhizobium </em>asupra creșterii, dezvoltării și productivității plantelor de tomate și castraveți. S-a stabilit că tratarea semințelor cu metaboliții bacteriilor în concentrații optime (1:300; 1:500) stimulează creșterea și acumularea de masă uscată a plantelor. De asemenea, s-a in­ves­tigat și efectul bacteriilor asupra nematodelor fitoparazite – <em>Ditylenchus destructor</em>.
2
Rusu, Elena, Manole Cojocaru, Cristina Cristescu, Ionela Avram, and Diana Pelinescu. "Assessment of antimicrobian effect of certain lactic acid bacteria species." Romanian Journal of Infectious Diseases 18, no. 1 (2015): 20–23. http://dx.doi.org/10.37897/rjid.2015.1.3.
Full textAbstract:
At the gastrointestinal tract level there is a balance between microbiota and the digestive tract which has as effect differentiation of pathogenic bacteria commensal species. Lately, due to the development of new therapies and use of a wide spectrum antimicrobian compounds we can notice an increase in the number of opportunistic infections caused by potentially pathogenic bacterial and fungal strains. Lactic acid bacteria produce compounds with antimicrobian action, such as hydrogen peroxide, diacetyl, acetaldehyde, D-amino acids isomers, reutin and bacteriocines. The use of probiotics can represent a supplementary alternative for increasing and maintaining the well-being of the human body.
3
Sârbu, Ionela, Tatiana Vassu, Ileana Stoica, et al. "Analysis on the antimicrobial activity of some lactic acid bacteria strains." Romanian Journal of Infectious Diseases 18, no. 2-3 (2015): 87–91. http://dx.doi.org/10.37897/rjid.2015.2-3.6.
Full textAbstract:
Objective. The main objective of this study was to select lactic acid bacteria strains with antimicrobial activity and to identify and characterize the antimicrobial compounds. Methods. In this study we tested the antimicrobial activity of 153 lactic bacteria strains by disk diffusion method against 6 microbial pathogenic strains isolated from patients with urinary and vaginal infections. Results. Antimicrobial test results revealed that most of lactic acid bacteria strains exhibited high antimicrobial activity against pathogenic microorganisms. For most of lactic bacteria strains antimicrobial activity has been correlated with the production of organic acids and only for two strains with the biosynthesis of bacteriocins. Bacteriocin produced by Lactococcus (Lc.) lactis F2a strain presented a broad spectrum of activity and high activity (51,200 AU/ml) compared with bacteriocins isolated from Lactobacillus (Lb.) paracasei ssp. paracasei JR strain (400 AU/ml). The stability tests of bacteriocin revealed that the bacteriocin produced by Lc. lactis F2a strain, it is stable at acid pH while exposure for long time to 600C causes a drastic decrease in bacteriocin activity. Conclusions. Lactic bacteria strains showed a high antimicrobial activity against both prokaryotic and eukaryotic pathogen strains. Two bacterial strains have bacteriocins. Bacteriocins isolated from Lc. lactis F2a strain showed a high activity and a broad spectrum of action.
4
Nicoleta, VORNICU. "Biodeteriorarea picturii murale de la Biserica "Adormirea Maicii Domnului", Căușeni, Republica Moldova." DIALOGICA. Cultural Studies and Literature Scientific Journal, CHISINAU, REPUBLIC OF MOLDOVA Vol. 12, no. 3/2022 (2022): 52–56. https://doi.org/10.5281/zenodo.7489618.
Full textAbstract:
Lucrarea prezintă complexitatea evaluări stării de degradare la pictura murală din interiorul Bisericii „Adormirea Maicii Domnului” din Căușeni și necesitatea unei abordări multidisciplinare a cercetării, pentru a obține o imagine cât mai clară a stării de conservare. Microorganismele identificate, care s-au dezvoltat la suprafaţa sau în profunzimea stratului pictural, sunt bacteriile și fungii. Tipul de microorganism predominant depinde de compoziţia chimică a substratului, temperatură și umiditate, factori care potențează dezvoltarea acestora. Microorganismele produc în timp modificări de natură chimică astfel încât suprafaţa afectată își pierde integritatea prin modificările de coeziune și au loc modificări cromatice (modificări estetice). Astfel hifele fungice/actinomicetele pătrund prin fisuri determinând lărgirea acestora. Atât distribuția numerică cât și apartenența taxonomică a biodeteriogenilor pe frescele din interiorul bisericii de la Căușeni sunt diferite în funcție de nutrienții disponibili (fungi Aspergillus niger, Fusarium sp, Penicillium, bacterii Actinomyces sp.).
5
GOLBAN, Rita. "EVALUĂRI MICROBIOLOGICE ALE UNOR SORTIMENTE DE BRÂNZETURI." Știința Agricolă, no. 1 (August 2022): 125–34. http://dx.doi.org/10.55505/sa.2022.1.18.
Full textAbstract:
Cercetările ştiinţifice reflectate în acest studiu au avut ca scop studierea microflorei bacteriene în unele sortimente de brânzeturi în stare proaspătă și în diverse perioade de refrigerare, comercializate în rețeaua industrială, după schema conduitei microbiologice clasice de laborator. Prin cercetări bacterioscopice și bacteriologice s-a evaluat numărul de colonii microbiene Streptococcus, Lactobacillus, ale celulelor levurice și ale speciilor condiționat patogene în brânzeturi cu pastă tare și moale. Rezultatele au confirmat o microfloră bacteriană normală obținută prin mecanismul de fermentaţie lactică. Microorganisme potențial patogene din categoriile Salmonella, Staphylococcus și bacterii coliforme nu au fost identificate. Aceste cercetări prezintă interes public, demonstrând că produsele lactate comercializate în reţeaua de magazine sunt calitative şi corespund cerinţelor de siguranță alimentară și de comercializare.
6
Dubceac, Marcela, Evghenii Haustov, and Victor Bondarciuc. "Implementarea metodei PCR pentru identificarea tulpinilor patogene Allorhizobium Vitis ce provoacă cancerul bacterian al viței-de-vie." Agricultural Science, no. 1 (July 5, 2024): 47–54. http://dx.doi.org/10.55505/sa.2024.1.05.
Full textAbstract:
In the process of obtaining grapevine clones free from viral diseases and bacterial cancer, there are often cases where protoclones, seemingly healthy, well-developed, and with high yields, are found to be latently infected with bacterial cancer. This disease is most caused by agrobacteria from the genus Allorhizobium vitis and sometimes by Agrobacterium tumefaciens, and it is one of the most destructive diseases for grapevines from an economic perspective. The bacterial pathogen exists systemically in grapevines and spreads through infected propagation material. In the present study the Triplex End-Point PCR method was used for accurate and rapid identification of pathogenic strains of agrobacteria. One-year-old mature vines from 6 varieties and forms of grapevines were taken for the research. Microbiological testing on Roy & Sasser semiselective medium showed that five of the six plants tested were positive for Agrobacterium spp. infection. The positive tested samples were subjected to PCR testing. The presence of PehA gene, which is used to identify Allorhizobium vitis and to differentiate it from Agrobacterium tumefaciens, was confirmed in all tested samples. The virF and virD regions associated with the production of nopalins, octopins and vitopns were also detected. The test results suggested that the method allows for the reliable detection of pathogenic cultures carrying the tumor-inducing plasmid. The obtained results contribute to the development of strategies to combat bacterial cancer infections and improve phytosanitary selection practices for grapevine propagation material. În procesul de obținere a clonelor de viță de vie libere de boli virale și de cancer bacterian, adesea se observă cazuri în care plantele, aparent sănătoase, bine dezvoltate și cu o producție ridicată, se dovedesc a fi infectate latent cu cancer bacterian. Această boală este cauzată cel mai des de agrobacterii din genul Allorhizobium vitis și uneori de Agrobacterium tumefaciens și este una dintre cele mai distructive boli, din perspectivă economică, pentru vița de vie. Patogenul bacterian există sistemic în vița de vie și se răspândește prin materialul de propagare infectat. În prezentul studiu a fost utilizată metoda PCR Triplex End-Point pentru identificarea precisă și rapidă a tulpinilor patogene de agrobacterii. Pentru realizarea cercetărilor au fost prelevate vițe mature de un an de la 6 soiuri și forme de viță de vie. Testarea microbiologică pe mediul semiselectiv Roy & Sasser a demonstrat că cinci dintre cele 6 plante testate au prezentat rezultate pozitive pentru infecția cu Agrobacterium spp. Loturile testate pozitiv au fost transferate la etapa investigației prin metoda PCR. În toate probele testate a fost confirmață prezența genei PehA (466 bp), care servește pentru identificarea bacteriei Allorhizobium vitis și pentru diferențierea ei de Agrobacterium tumefaciens. De asemenea s-au detectat regiunile virF (382 bp) și virD (320 bp) asociate cu producția de nopaline, octopine și vitopine, ce servesc drept sursă de nutrienți pentru bacterii. Rezultatele testărilor au sugerat că metoda permite detectarea fiabilă a culturilor patogene purtătoare de plasmida inductoare de tumori. Rezultatele obținute contribuie la dezvoltarea strategiilor de combatere a infecțiilor cu cancer bacterian și la îmbunătățirea practicilor de selecție fitosanitară a materialului de multiplicare viticol.
7
Dubceac, Marcela, Evghenii Haustov, and Victor Bondarciuc. "Implementarea metodei PCR pentru identificarea tulpinilor patogene Allorhizobium vitis ce provoacă cancerul bacterian al viței-de-vie." Agricultural Science, no. 1 (June 7, 2024): 47–54. https://doi.org/10.55505/sa.2024.1.05.
Full textAbstract:
In the process of obtaining grapevine clones free from viral diseases and bacterial cancer, there are often cases where protoclones, seemingly healthy, well-developed, and with high yields, are found to be latently infected with bacterial cancer. This disease is most caused by agrobacteria from the genus Allorhizobium vitis and sometimes by Agrobacterium tumefaciens, and it is one of the most destructive diseases for grapevines from an economic perspective. The bacterial pathogen exists systemically in grapevines and spreads through infected propagation material. In the present study the Triplex End-Point PCR method was used for accurate and rapid identification of pathogenic strains of agrobacteria. One-year-old mature vines from 6 varieties and forms of grapevines were taken for the research. Microbiological testing on Roy & Sasser semiselective medium showed that five of the six plants tested were positive for Agrobacterium spp. infection. The positive tested samples were subjected to PCR testing. The presence of PehA gene, which is used to identify Allorhizobium vitis and to differentiate it from Agrobacterium tumefaciens, was confirmed in all tested samples. The virF and virD regions associated with the production of nopalins, octopins and vitopns were also detected. The test results suggested that the method allows for the reliable detection of pathogenic cultures carrying the tumor-inducing plasmid. The obtained results contribute to the development of strategies to combat bacterial cancer infections and improve phytosanitary selection practices for grapevine propagation material. În procesul de obținere a clonelor de viță de vie libere de boli virale și de cancer bacterian, adesea se observă cazuri în care plantele, aparent sănătoase, bine dezvoltate și cu o producție ridicată, se dovedesc a fi infectate latent cu cancer bacterian. Această boală este cauzată cel mai des de agrobacterii din genul Allorhizobium vitis și uneori de Agrobacterium tumefaciens și este una dintre cele mai distructive boli, din perspectivă economică, pentru vița de vie. Patogenul bacterian există sistemic în vița de vie și se răspândește prin materialul de propagare infectat. În prezentul studiu a fost utilizată metoda PCR Triplex End-Point pentru identificarea precisă și rapidă a tulpinilor patogene de agrobacterii. Pentru realizarea cercetărilor au fost prelevate vițe mature de un an de la 6 soiuri și forme de viță de vie. Testarea microbiologică pe mediul semiselectiv Roy & Sasser a demonstrat că cinci dintre cele 6 plante testate au prezentat rezultate pozitive pentru infecția cu Agrobacterium spp. Loturile testate pozitiv au fost transferate la etapa investigației prin metoda PCR. În toate probele testate a fost confirmață prezența genei PehA (466 bp), care servește pentru identificarea bacteriei Allorhizobium vitis și pentru diferențierea ei de Agrobacterium tumefaciens. De asemenea s-au detectat regiunile virF (382 bp) și virD (320 bp) asociate cu producția de nopaline, octopine și vitopine, ce servesc drept sursă de nutrienți pentru bacterii. Rezultatele testărilor au sugerat că metoda permite detectarea fiabilă a culturilor patogene purtătoare de plasmida inductoare de tumori. Rezultatele obținute contribuie la dezvoltarea strategiilor de combatere a infecțiilor cu cancer bacterian și la îmbunătățirea practicilor de selecție fitosanitară a materialului de multiplicare viticol.
8
Nica, M., T. Biolan, E. Turcu, et al. "Dinamic of resistance to antibiotics for the most frequent potential pathogen bacterial isolates in “Dr. V. Babes” Clinical Hospital of Infectious and Tropical Diseases (2000-2015)." Romanian Journal of Infectious Diseases 19, no. 2 (2016): 78–89. http://dx.doi.org/10.37897/rjid.2016.2.6.
Full textAbstract:
Objective. Analyzing the dynamycs of global antibiotic resistance of some bacterial species isolated from patients admitted to the „Dr. V. Babes” Hospital for Infectious and Tropical Diseases, between the years 2000 to 2015. Material and methods. Antibiotic resistance profiles of bacteria isolated from inpatients, were identified by the standard diffusion method and MIC values by VITEK2C and E-test methods. (CLSI and EUCAST standards). Screening of carbapenemases – producing isolates were performed by phenotipic methods, and the confirmation by RealTimePCR: “MasterPure™ Complete DNA and RNA Purification Kit” (Epicentre), „Primer Design™ Kit” (blaOXA48; blaKPC, blaNDM, blaVIM)/ LightScanner 32 Instrument/LS32 (Idaho Technology), and GeneXpert. Internal quality control: Staphylococcus aureus ATCC29213, Streptococcus pneumoniae ATCC49619, E. coli ATCC25922, Pseudomonas aeruginosa ATCC27853. Results. The incidence of St. aureus meticilino-rezistent (MRSA) highlights an increase from 12.2% (2002) to 40.4% (2015). In the past 3 years SVB microbiology lab found a sharp increase in the incidence of erytromycin resistant strains of Streptococcus pyogenes. In 2015 we registered 20.3% of macrolide resistant strains. Global resistance to penicillin G for Str. pneumoniae (non-meningeal infections) was 45.3%- 54.5% until 2009, and 2.7% in 2013. Enterococcus faecium strains showed 0% resistance to vancomycin between 2000 and 2012. A significant growth was recorded in 2015 of 11%. Isolation rate of Klebsiella pneumoniae ESBL producing strains has increasewd progressively from 17.6 in 2000 to 57% in 2015. Carbapenems – resistant K. pneumoniae isolated strains were 18,8% in 2015. Carbapenemases types identified by phenotypic and genetic methods where: 35/ Oxa48, 8 KPC and 21/MBL (NDM-1). Resistance to carbapenems recorded an upward trend: 23.9% in 2004 to 37.9% in 2015, and for Acinetobacter baumannii 69%. Conclusions. Antibiotic resistance of bacteria is a major challenge for public healts. Therapeutic solutions are extremely limited.
9
Laura, Abisaí Pazos-Rojas, Rodríguez-Andrade Osvaldo, Catalina Muñoz-Arenas Ligia, et al. "Desiccation-Tolerant Rhizobacteria Maintain their Plant Growth- Promoting Capability after Experiencing Extreme Water Stress." SciFed Journal of Applied Microbiology 1, no. 1 (2018): 1–13. https://doi.org/10.5281/zenodo.5068936.
Full textAbstract:
Abstract Bacteria from rhizosphere have the potential to promote the growth of plants, and could be used as inoculants to increase the crop profitability. However, under drought stress conditions, the number of bacteria associated to seeds could decrease below the minimal number of bacteria required to obtain a positive plant response. At the present work, the capability of 28 rhizospheric bacterial strains to tolerate 18 days of air desiccation stress (at 30oC and 50% of relative humidity) was evaluated. Results showed different levels of bacterial tolerance and five categories were proposed based on the bacterial survival ratio to air desiccation (BSRad): highly tolerant bacteria (BSRad˃80), tolerant (60<BSRad≤80), middle tolerant (40<BSRad≤60), low tolerant (20<BSRad≤40), and very low-tolerant (BSRad≤20). Highly tolerant and very low-tolerant bacteria were selected to inoculate maize seeds. After inoculation, seeds were subjected to desiccation conditions for 18 days and then sown in sterile vermiculite and watered with MS solution. Only highly tolerant strains were able to survive associated to seeds under desiccation conditions keeping their beneficial traits such as, bacterial adherence, colonization and plant growth promotion. In contrast, the very-low tolerant bacterial strain was not able to colonize the rhizosphere nor promote the growth of the plants. Tolerant bacteria to desiccation have desirable traits in comparison to non-tolerant bacteria, because they could be more stable in powder presentations of inoculants without need of protectants, they could survive with higher numbers in soils with low water availability keeping their ability to promote the plant-growth until the end of adverse conditions; when the seed germination take place.
10
Juárez-González, Victor Rivelino, Victor Hugo Guadarrama-Pérez, David Vasco-Julio, Elian Yuritzi Alegría-Herrera, and Jesús Hernández-Romano. "Las endolisinas de fagos como una fuente alternativa para la eliminación de bacterias multirresistentes." Alianzas y Tendencias BUAP 9, no. 34 (2024): 40–64. https://doi.org/10.5281/zenodo.12502858.
Full textAbstract:
RESUMEN En los últimos 20 años, el uso indiscriminado de antibióticos en humanos para el tratamiento de enfermedades bacterianas, ha promovido el rápido desarrollo de microorganismos multidrogorresistentes (MDR). La Organización Mundial de la Salud (OMS) liberó en 2017 una lista de bacterias para las que se requieren urgentemente nuevos antibióticos, clasificándolas en tres categorías: 1) crítica, 2) de alta prioridad o 3) media prioridad. Dichas cepas, si no son atendidas en el corto plazo, probablemente provoquen una nueva pandemia silente, de la cual ya se tiene los primeros atisbos. Los bacteriófagos o fagos son virus que infectan únicamente a bacterias. Una vez dentro de ellas y al final de su ciclo replicativo, tienen la capacidad de degradar el peptidoglicano que forma la pared celular de dichos microorganismos, utilizando para ello enzimas conocidas como endolisinas, provocando la muerte de las bacterias por medio de lisis celular, liberándose así la nueva progenie de viriones. La ausencia de una membrana externa en las bacterias Gram-positivas, permitiría que las endolisinas puedan llegar al peptidoglicano y destruir estos microorganismos cuando sean aplicadas externamente como medio terapéutico. De igual forma, se han caracterizado endolisinas fágicas que tienen la capacidad de inhibir el crecimiento de bacterias Gram-negativas. Esta interesante característica de degradación de la pared celular, ocasiona que las endolisinas sean consideradas posibles candidatos a agentes antimicrobianos, debido al actual aumento de la resistencia bacteriana a los antibióticos. ABSTRACT Over the past 20 years, the indiscriminate use of antibiotics in humans for the treatment of bacterial diseases has promoted the rapid development of multidrug-resistant (MDR) microorganisms. The World Health Organization (WHO) released in 2017 a list of bacteria for which new antibiotics are urgently required, classifying them into three categories: 1) critical, 2) high priority or 3) medium priority. These strains, if not addressed in the short term, are likely to cause a new silent pandemic, of which we already have the first glimpses. Bacteriophages or phages are viruses that infect only bacteria. Once inside them and at the end of their replicative cycle, they have the capacity to degrade the peptidoglycan that forms the cell wall of these microorganisms, using enzymes known as endolysins, causing the death of the bacteria by means of cell lysis, thus releasing the new progeny of virions. The absence of an external membrane in Gram-positive bacteria would allow endolysins to reach the peptidoglycan and destroy these microorganisms when applied externally as a therapeutic means. Similarly, phage endolysins have been characterized that have the ability to inhibit the growth of Gram-negative bacteria. This interesting characteristic of cell wall degradation causes endolysins to be considered as possible candidates for antimicrobial agents, due to the current increase in bacterial resistance to antibiotics.
Dissertations / Theses on the topic "Bacterii"
1
Maldonado, Vázquez Jesús Manuel. "Interferometric biosensors for rapid identification of nosocomial infections." Doctoral thesis, Universitat Autònoma de Barcelona, 2017. http://hdl.handle.net/10803/403761.
Full textAbstract:
Esta tesis doctoral se centra en el desarrollo de un nuevo biosensor óptico como una técnica alternativa para la identificación de infecciones nosocomiales con el fin de determinar el tratamiento más eficaz y reducir el uso inespecífico de fármacos antimicrobianos de amplio espectro. Proponemos el uso de un nuevo sensor nanofótonico basado en un dispositivo interferométrico, el biosensor de guías de onda bimodales (BiMW) para un análisis rápido, específico, directo y altamente sensible de los diferentes patógenos asociados a infecciones nosocomiales y su resistencia a múltiples fármacos. En primer lugar, se evaluaron y optimizaron diferentes estrategias de biofuncionalización para conseguir una inmovilización eficiente de los elementos de bioreconocimiento que aseguran una detección bacteriana altamente sensible con suficiente selectividad y reproducibilidad, particularmente para la detección directa en matrices complejas tales como orina y líquido ascítico. Posteriormente, las estrategias optimizadas se utilizaron para la identificación de diversos patógenos nosocomiales como Bacillus cereus, Escherichia coli y Pseudomonas aeruginosa utilizando anticuerpos como elementos de bioreconocimiento. La detección de Escherichia coli se realizó en una matriz compleja como es el líquido ascítico humano. Finalmente, el biosensor BiMW se empleó para identificar bacterias resistentes a múltiples fármacos como: i) la identificación de Staphylococcus aureus resistente a meticilina (MRSA) usando un aptámero, que es capaz de discriminar entre un Staphylococcus susceptible a antibióticos y un Staphylococcus multirresistente y (ii) la detección ultra sensible de genes de E. coli resistentes a múltiples fármacos, sin la necesidad de una previa amplificación por PCR.
En general, esta tesis aprovecha los conocimientos en biosensores fotónicos y en métodos bioanalíticos de nuestro Grupo de investigación para desarrollar una poderosa herramienta que permita la identificación directa y efectiva de patógenos nosocomiales y su resistencia a antibióticos.<br>This doctoral Thesis is focusing on the development of a novel optical biosensor as an alternative technique for the identification of nosocomial infections in a faster way. This new tool will also facilitate the finding of the most effective treatment for each patient, reduce the nonspecific use of broad-spectrum antimicrobial drugs, and facilitate new antibiotic treatments. We propose the use of a novel nanophotonic sensor based on an interferometric transducer device, the Bimodal Waveguide device (BiMW) for the rapid, specific, highly sensitive and direct analysis of different pathogens associated to nosocomial infections and their multidrug resistant. First, we assessed and optimized different biofunctionalization strategies for an efficient immobilization of the required biorecognition receptors, which ensure a highly sensitive bacterial detection with enough selectivity and reproducibility, particularly suitable for the direct detection in complex matrices, such as urine and ascitic fluid. The optimized strategies were employed for the identification of various nosocomial pathogens such as Bacillus cereus, Escherichia coli, and Pseudomonas aeruginosa using antibodies as biorecognition elements. The detection of Escherichia coli was done in human ascitic fluid. Finally, the BiMW biosensor was employed to identify the multidrug-resistant bacteria such as: i) the identification of methicillin-resistant Staphylococcus aureus (MRSA) using a specific aptamer, which is able to discriminate among a susceptible one to antibiotic and a multidrug-resistant Staphylococcus, and (ii) the ultra-sensitive detection of multidrug-resistant E. coli genes without PCR amplification.
This Thesis takes advantage of the knowledge in photonics biosensors and bioanalytical methods in our Group in order to develop a powerful tool for the direct and effective identification of nosocomial pathogens and their antibiotic-resistance in a rapid and label-free scheme.
2
Moyà, Anderico Laura. "Deciphering the utility of Galleria mellonella as an infection and toxicity in vivo model." Doctoral thesis, Universitat de Barcelona, 2021. http://hdl.handle.net/10803/671803.
Full textAbstract:
Galleria mellonella (greater wax moth) is a popular animal model that has been extensively used as an alternative in vivo model for investigating the virulence and pathogenicity of different bacteria. G. mellonella has also been shown to be a suitable model for studying the efficacy and toxicity of various compounds. Recently, this model has been gaining popularity as the larvae are conveniently sized for manipulation, they do not need constant feeding, they are inexpensive to purchase and to breed, they do not require much space or special infrastructure, they present a low biohazard risk, and they are more ethically accepted. More importantly, G. mellonella has an innate immune system very similar to the one found in mammals. In this thesis, G. mellonella was used to develop a standardized and reproducible animal model of infection and toxicity.
Pseudomonas aeruginosa is an opportunistic pathogen that has gained great medical importance as it causes serious illnesses in humans and it can be resistant to many antibiotics. During infection, ribonucleotide reductases (RNR) play an essential role as they catalyze the reduction of ribonucleotides to deoxyribonucleotides, thus providing the precursor molecules needed for DNA synthesis. Since G. mellonella has been proven to be a suitable model for P. aeruginosa infections, we developed a promoter probe vector with bioluminescence expression to enhance the study and monitoring of a P. aeruginosa in vivo infection. This vector was used to construct different RNR gene promoter fusions as proof of concept. Additionally, we optimized a total bacterial RNA extraction protocol to facilitate the study of transcriptional gene levels during in vivo infections.
Staphylococcus aureus is also considered an opportunistic pathogen. This bacterium is also capable of forming biofilms and it is considered an important cause of biofilm formation in catheters and prostheses. Due to the misuse and overuse of antimicrobials, multi-resistant bacteria are rapidly appearing so there is a critical need for new antimicrobials. The toxicity and antimicrobial efficacy against S. aureus of novel oleanolic and maslinic acid derivatives were determined using G. mellonella. Out of the 14 derivatives tested, 2 were found to have improved toxicity and efficacy in vivo when compared to the in vitro results.
G. mellonella was also used to test the toxicity of other therapeutical strategies and nanoparticles (NPs). Mycolicibacterium brumae was not toxic to G. mellonella larvae, and the results correlated with the results obtained with mice. The different NPs caused a variety of acute toxicity effects that were detected by an array of indicators within the larvae, such as lethal dose calculation, hemocyte proliferation, NP distribution, behavioral changes, and histological alterations. Due to the broad applicability of the G. mellonella model, new methodologies are warranted to exploit its full potential. Besides the optimized RNA extraction protocol already mentioned, an optical clearing protocol was also optimized in this work. As a proof of concept for our larvae clearance protocol, fluorescent rhodamine NPs were injected into larvae that were then fixed with paraformaldehyde, permeabilized with increasing concentrations of methanol, and cleared with BABB (Benzyl Alcohol and Benzyl Benzoate).<br>Galleria mellonella es un modelo animal utilizado extensamente como alternativa para investigar la virulencia y patogenicidad bacteriana in vivo. También es apropiado para estudiar la eficacia y toxicidad de compuestos. Las larvas tienen un tamaño manejable, son económicas de adquirir y reproducir, presentan un bajo riesgo biológico, y son más aceptadas
éticamente. Además, tienen un sistema inmunológico innato muy similar al de los mamíferos. Utilizamos G. mellonella para desarrollar un modelo animal de infección y toxicidad estandarizado y reproducible.
Pseudomonas aeruginosa, un patógeno oportunista, que infectando emplea ribonucleótido reductasa (RNR), catalizando la reducción de ribonucleótidos a desoxirribonucleótidos y proporcionando así las moléculas precursoras necesarias para la síntesis de ADN. Desarrollamos un vector sin promotor con bioluminiscencia, el cual se utilizó para construir fusiones con los promotores de los genes RNR. Además, optimizamos un protocolo de extracción de ARN bacteriano para facilitar el estudio de los niveles transcripcionales de genes in vivo.
Debido a la multiresistencia emergente de Staphylococcus aureus, se probó la toxicidad
y eficacia antimicrobiana de nuevos derivados del ácido oleanólico y maslínico en G. mellonella. De los catorce derivados probados, dos tenían menos toxicidad y más eficacia in vivo que in vitro.
G. mellonella se usó para determinar la toxicidad de nanopartículas y estrategias terapéuticas. Mycolicibacterium brumae no fue tóxica para las larvas y los resultados se correlacionaron con los obtenidos con ratones. Las nanopartículas causaron efectos tóxicos en las larvas detectados por la medición de la dosis letal y la proliferación de hemocitos, entre otros indicadores.
Debido a la amplia aplicabilidad de G. mellonella, se necesitan nuevas metodologías para maximizar su potencial. Además del protocolo de extracción de ARN previamente mencionado, también se optimizó otro de aclaramiento. Las larvas fueron inyectadas con nanopartículas, fijadas con paraformaldehído, permeabilizadas con metanol y aclaradas con alcohol bencílico y benzoato de bencilo.
3
Gaviria, Cantín Tania Cristina. "Factores Gre de Salmonella enterica serovar Typhimurium, su papel en el control de la filosofía y patogenicidad." Doctoral thesis, Universitat de Barcelona, 2016. http://hdl.handle.net/10803/397788.
Full textAbstract:
El género Salmonella, está compuesto de bacterias Gram-negativas, no esporuladas, en forma de bacilo. Salmonella tiene importante relevancia a nivel de salud pública ya que es uno de los principales patógenos entéricos tanto en países desarrollados como en vías de desarrollo. En los casos de gastroenteritis notificados en España, Salmonella se posiciona en segundo lugar, después de Campylobacter. En este trabajo se utilizó como organismo modelo de estudio S. enterica serovar Typhimurium (S. Typhimurium), que en humanos causa salmonelosis, gastroenteritis caracterizada por diarrea inflamatoria, originada normalmente tras la ingestión de alimentos o agua contaminados. Los genes de virulencia de S. Typhimurium están localizados mayoritariamente dentro de islas de patogenicidad (SPI). Los genes codificados en la SPI-1 promueben la invasión de células eucariotas, la regulación de la expresión de los genes de la SPI-1 está mediada por HiIA codificada en el gen, hilA, presente en la misma SPI-1. HiIA activa la expresión de los genes que codifican para la síntesis de un sistema de secreción de tipo 3 (T3SS) encargado de secretar e inyectar proteínas efectoras dentro de la célula hospedadora. La expresión de hilA se encuentra bajo el control de unl bucle de regulación, comprendido por las proteínas HiID, HiIC y RtsA. HiID es el regulador predominante de este sistema, mientras que HiIC y RtsA se encargan de amplificar la señal de activación. Por su parte, los genes que contiene la SPI-2, están implicados en causar infecciones sistémicas y la proliferación intracelular de la bacteria. Los factores Gre son factores que regulan la elongación de la transcripción génica en procariotas. Son conocidos por promover la actividad endorribonucleotídica de la ARN polimerasa (ARNpol) cuando ésta se encuentra en un estado de pausa por retroceso causado durante la elongación de la transcripción. A pesar de que los factores Gre han sido bien caracterizados en otras enterobacterias como Escherichia coli, en Salmonella no existen estudios que describan el papel de los factores Gre en la fisiología celular. Así, el objetivo principal de esta tesis doctoral fue estudiar el papel de los factores Gre en la fisiología y patogenicidad de Salmonella. En este estudio describimos que los factores Gre forman parte de la compleja red reguladora de la expresión de los genes de la SPI-1 y SPI-2 de Salmonella. Los resultados obtenidos indican que los factores Gre de Salmonella son esenciales para la correcta expresión de las proteínas efectoras codificadas dentro de la SPI-1 (SipA, SipC y SipD) y fuera de ella (SopE), y que también juegan un papel importante en la motilidad de la célula bacteriana, fenotipos predominantes en la patogenicidad. Se pudo determinar que la regulación de la expresión de los genes de la SPI-1 y la SPI-2 por parte de los factores Gre, es a través de la regulación transcripcional del gen hilD. La regulación mediada por los factores Gre requiere de la región 3'UTR del gen hilD. Además demostramos que la actividad antipausa de la transcripción de los factores Gre es necesaria para la correcta expresi formación de biofilm en Salmonella. Esta regulación al parecer también es ejercida en una región UTR, en este caso en la región 5’UTR del gen csgD, y es independiente de la temperatura. En análisis transcriptómicos mediante la técnica de microarrays, se observó que los factores Gre de Salmonella estarían implicados en la correcta expresión de muchos de los genes adquiridos horizontalmente (HGT)
como son los genes presentes en las islas de patogenicidad, plásmidos y fagos. También se observó que existe un elevado número de genes distribuidos en diferentes categorías funcionales, que son corregulados por los factores Gre en conjunto con la proteína DksA, proteína que incrementa la fidelidad de la transcripción al disminuir la tasa de incorporación incorrecta de nucleótidos. Estos resultados indican que el patrón general de expresión génica de Salmonella es el resultado de una compleja interacción entre los factores Gre y la proteína DksA, que implica el control mutuo, competición por la unión a la ARNpol, y la acción similar u opuesta sobre la actividad de la ARNpol. Con los resultados presentados en esta tesis doctoral se puede concluir que los factores Gre forman parte de la compleja red de regulación de los genes de virulencia de Salmonella.ón de hilD.<br>Gre factors regulate gene transcription elongation in prokaryotes. In Escherichia coli they promote cleavage of the nascent RNA transcript within the elongation complex when the RNA polymerase is paused by a backtracking. Although the Gre factors have been characterized in other enterobacteria, in Salmonella there are not studies about their role in cellular physiology. The main objective of this thesis was to study the role of Gre factors in physiology and pathogenicity of Salmonella. In this study we describe Gre factors that are part of the complex regulatory network of gene expression of Salmonella pathogenicity island-1 (SPI-1) and SPI-2.
The results indicate that Gre factors are pivotal in the control of predominant phenotypes in pathogenicity. They are essential for the correct expression of effector proteins encoded within (SipA, SipC and SipD) and outside SPI-1 (SopE), and they also play an important role in motility of the bacterial cell. It was determined that the regulation of gene expression of SPI-1 and SPI-2 by Gre factors is through transcriptional regulation of hilD gene. Regulation mediated by Gre factors requires hilD 3'UTR region. We demonstrated that Gre antipausa activity during transcription is necessary for the correct expression of hilD.
It was also observed that Gre factors play an important role in transcriptional expression of csgD, main regulator of biofilm formation in Salmonella. This regulation is also apparently exerted through the 5'UTR region of the csgD gene, and is temperature- independent.
In transcriptome analysis using Microarray, it was observed that Gre factors are implicated in the correct expression of many horizontally transferred genes (HGT) such as genes present in pathogenicity islands, plasmids and phages. It was also noted that there is a large number of genes distributed into different functional categories, which are co-regulated by Gre factors together with DksA protein, a protein that increases the accuracy of the transcript to decrease the rate of nucleotide missincorporation. These results indicate that the overall pattern of gene expression of Salmonella is the result of a complex interaction between Gre factors and DksA protein, involving the mutual control, competition for binding to ARNpol, and similar or opposite action on ARNpol activity. We can conclude that Gre factors are part of complex regulatory network of virulence genes of Salmonella.
4
Kassotaki, Elissavet. "Elimination of micropollutants in conventional and novel nitrogen removal processes. A comparative assessment of diverse microbial communities capabilities." Doctoral thesis, Universitat de Girona, 2018. http://hdl.handle.net/10803/664342.
Full textAbstract:
Pharmaceutically active compounds (PhACs) and endocrine disrupting compounds (EDCs) can pose a significant risk to the environment and human health, undermining prosperity. Current wastewater treatment plants (WWTPs) cannot efficiently act as barriers to their release and have been identified as main points of discharge and contamination. The present thesis aimed to investigate the fate of five PhACs (ibuprofen, sulfamethoxazole, metoprolol, carbamazepine and venlafaxine) and five EDCs (estrone, 17β-estradiol, estriol, 17α-ethinylestradiol and bisphenol A) in different systems simulating wastewater treatment scenarios and to identify factors triggering their elimination. A comparative assessment was carried out to determine the contribution of the microbial groups (either autotrophic or heterotrophic) present in different lab, pilot and full-scale treatment systems performing different processes in the removal of the selected compounds. The results indicated that the overall efficiency of wastewater treatment systems can be broadened by combining different aerobic and anaerobic conditions and different types of biomass<br>Els compostos farmacèuticament actius (PhACs) i els pertorbadors endocrins(EDC) poden suposar un risc considerable per al medi ambient i la salut humana. Les estacions depuradores d'aigües residuals (EDAR) no poden actuar de manera eficient com a barreres per al seu alliberament i s'han identificat com a punts principals de descàrrega. La present tesi pretén determinar el destí de cinc PhACs (ibuprofèn, sulfametoxazol, metoprolol, carbamazepina i venlafaxina) i cinc EDCs (estrona, 17β-estradiol, estriol, 17α-etinilestradiol i bisfenol A), en sistemes que simulen escenaris de tractament d'aigües residuals, per identificar els factors claus en la seva eliminació. Es va realitzar una avaluació comparativa per determinar la contribució dels diferents grups bacterians (autòtrofs o heteròtrofs) presents en diferents sistemes a escala de laboratori, pilot i a gran escala. Els resultats indiquen que l'eficiència global dels sistemes de tractament d'aigües residuals es pot ampliar combinant diferents condicions aeròbiques i anaeròbies i tipus de biomassa
5
de, Klerk Nele. "Host-bacteria interactions : Host cell responses and bacterial pathogenesis." Doctoral thesis, Stockholms universitet, Institutionen för molekylär biovetenskap, Wenner-Grens institut, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-126425.
Full textAbstract:
Helicobacter pylori colonizes the human stomach, where it causes gastritis that may develop into peptic ulcer disease or cancer when left untreated. Neisseria gonorrhoeae colonizes the urogenital tract and causes the sexually transmitted disease gonorrhea. In contrast, Lactobacillus species are part of the human microbiota, which is the resident microbial community, and are considered to be beneficial for health. The first host cell types that bacteria encounter when they enter the body are epithelial cells, which form the border between the inside and the outside, and macrophages, which are immune cells that engulf unwanted material. The focus of this thesis has been the interaction between the host and bacteria, aiming to increase our knowledge of the molecular mechanisms that underlie the host responses and their effects on bacterial pathogenicity. Understanding the interactions between bacteria and the host will hopefully enable the development of new strategies for the treatment of infectious disease. In paper I, we investigated the effect of N. gonorrhoeae on the growth factor amphiregulin in cervical epithelial cells and found that the processing and release of amphiregulin changes upon infection. In paper II, we examined the expression of the transcription factor early growth response-1 (EGR1) in epithelial cells during bacterial colonization. We demonstrated that EGR1 is rapidly upregulated by many different bacteria. This upregulation is independent of the pathogenicity, Gram-staining type and level of adherence of the bacteria, but generally requires viable bacteria and contact with the host cell. The induction of EGR1 is mediated primarily by signaling through EGFR, ERK1/2 and β1-integrins. In paper III, we described the interactions of the uncharacterized protein JHP0290, which is secreted by H. pylori, with host cells. JHP0290 is able to bind to several cell types and induces apoptosis and TNF release in macrophages. For both of these responses, signaling through Src family kinases and ERK is essential. Apoptosis is partially mediated by TNF release. Finally, in paper IV, we showed that certain Lactobacillus strains can reduce the colonization of H. pylori on gastric epithelial cells. Lactobacilli decrease the gene expression of SabA and thereby inhibit the binding mediated by this adhesin.<br><p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 4: Manuscript.</p>
6
Lawlor, Kirsten. "Distribution of bacteria and bacterial plasmids in lake water sediments." Thesis, University of Liverpool, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240596.
Full text
7
Sebastião, Isis [UNESP]. "Toxicidade e interação de proteínas Cry1 de Bacillus thuringiensis em Helicoverpa armigera (Hübner) (Lepidóptera: Noctuidae)." Universidade Estadual Paulista (UNESP), 2015. http://hdl.handle.net/11449/123869.
Full textAbstract:
Made available in DSpace on 2015-06-17T19:34:09Z (GMT). No. of bitstreams: 0
Previous issue date: 2015-02-26. Added 1 bitstream(s) on 2015-06-18T12:49:23Z : No. of bitstreams: 1
000829428_20170301.pdf: 100482 bytes, checksum: 894af24aad4ca7d75f9898581c07f398 (MD5) Bitstreams deleted on 2017-03-03T11:01:31Z: 000829428_20170301.pdf,. Added 1 bitstream(s) on 2017-03-03T11:02:40Z : No. of bitstreams: 1
000829428.pdf: 275587 bytes, checksum: 79098a3390015f4449a4b64413d932a8 (MD5)<br>Estudos que visam a interação das proteínas Cry de Bacillus thuringiensis, a fim de encontrar combinações adequadas para o desenvolvimento de plantas Bt são ferramentais fundamentais no controle de lepidópteros-praga. A lagarta H. armigera causa danos severos nas culturas agrícolas e sua introdução no Brasil levou a busca de formas de controle eficientes e nesse contexto B. thuringiensis pode ser um bom agente de controle. Diante do exposto o presente trabalho objetivou avaliar a toxicidade das proteínas Cry1Aa, Cry1Ab, Cry1Ac e Cry1Ca de B. thuringiensis à H. armigera, assim como interação dessas proteínas aos receptores do mesêntero do inseto. A toxicidade foi estimada com bioensaios de dose resposta com as proteínas testadas e a interação das proteínas com os receptores foram verificadas em análise de união entre a proteína ativada e marcada com a vesícula da borda em escova da membrana apical das células do intestino (brush border mambrane vesicle- BBMV) do mesêntero larval de H. armigera, e ensaios de competição heteróloga. Dentre as proteínas testadas, a Cry1Ac destacou-se como a mais efetiva, seguida das proteínas Cry1Ab e Cry1Aa. A proteína Cry1Ca não apresentou toxicidade. As proteínas Cry1Aa, Cry1Ab e Cry1Ac se ligaram aos receptores da membrana do intestino médio das lagartas de H. armigera de forma especifica. Os ensaios de competição heteróloga revelaram que as proteínas Cry1Aa, Cry1Ac e Cry1Ab competem entre si pelo mesmo receptor<br>Studies attempting interaction of Bacillus thuringiensis Cry proteins in order to find combinations for developing Bt plants are fundamental in controlling lepidopteran pests. H. armigera causes severe damage to agricultural crops and their introduction in Brazil has led the search for efficient control and B. thuringiensis may be a good control agent. The aim of this research was to evaluate the toxicity of Cry1Aa, Cry1Ab, Cry1Ac and Cry1Ca proteins from B. thuringiensis to H. armigera, as well as interaction of these proteins with the receptors present in insect midgut. Toxicity was estimated from the lethal concentration LC50 of the tested proteins and protein interactions with the receptors were found in a binding analysis between activated and biotinylated protein with the midgut brush border vesicle membrane (BBMV) of H. armigera, and heterologous competitive binding assays. Among the tested proteins, Cry1Ac protein was the most toxic, followed by the Cry1Ab and Cry1Aa proteins. The Cry1Ca protein showed no toxicity. The Cry1Aa, Cry1Ab and Cry1Ac proteins showed specific binding to the midgut membrane receptors of H. armigera caterpillars. Heterologous competitive binding assays revealed that Cry1Aa, Cry1Ab, Cry1Ac compete for a common receptor in the midgut larvae
8
Sebastião, Isis. "Toxicidade e interação de proteínas Cry1 de Bacillus thuringiensis em Helicoverpa armigera (Hübner) (Lepidóptera: Noctuidae) /." Jaboticabal, 2015. http://hdl.handle.net/11449/123869.
Full textAbstract:
Orientador: Manoel Victor Franco Lemos<br>Coorientador: Ricardo Antonio Polanczyk<br>Banca: Janete Apparecida Desidério<br>Banca: Camila Chiaradia Davolos<br>Resumo: Estudos que visam a interação das proteínas Cry de Bacillus thuringiensis, a fim de encontrar combinações adequadas para o desenvolvimento de plantas Bt são ferramentais fundamentais no controle de lepidópteros-praga. A lagarta H. armigera causa danos severos nas culturas agrícolas e sua introdução no Brasil levou a busca de formas de controle eficientes e nesse contexto B. thuringiensis pode ser um bom agente de controle. Diante do exposto o presente trabalho objetivou avaliar a toxicidade das proteínas Cry1Aa, Cry1Ab, Cry1Ac e Cry1Ca de B. thuringiensis à H. armigera, assim como interação dessas proteínas aos receptores do mesêntero do inseto. A toxicidade foi estimada com bioensaios de dose resposta com as proteínas testadas e a interação das proteínas com os receptores foram verificadas em análise de união entre a proteína ativada e marcada com a vesícula da "borda em escova" da membrana apical das células do intestino ("brush border mambrane vesicle"- BBMV) do mesêntero larval de H. armigera, e ensaios de competição heteróloga. Dentre as proteínas testadas, a Cry1Ac destacou-se como a mais efetiva, seguida das proteínas Cry1Ab e Cry1Aa. A proteína Cry1Ca não apresentou toxicidade. As proteínas Cry1Aa, Cry1Ab e Cry1Ac se ligaram aos receptores da membrana do intestino médio das lagartas de H. armigera de forma especifica. Os ensaios de competição heteróloga revelaram que as proteínas Cry1Aa, Cry1Ac e Cry1Ab competem entre si pelo mesmo receptor<br>Abstract: Studies attempting interaction of Bacillus thuringiensis Cry proteins in order to find combinations for developing Bt plants are fundamental in controlling lepidopteran pests. H. armigera causes severe damage to agricultural crops and their introduction in Brazil has led the search for efficient control and B. thuringiensis may be a good control agent. The aim of this research was to evaluate the toxicity of Cry1Aa, Cry1Ab, Cry1Ac and Cry1Ca proteins from B. thuringiensis to H. armigera, as well as interaction of these proteins with the receptors present in insect midgut. Toxicity was estimated from the lethal concentration LC50 of the tested proteins and protein interactions with the receptors were found in a binding analysis between activated and biotinylated protein with the midgut brush border vesicle membrane (BBMV) of H. armigera, and heterologous competitive binding assays. Among the tested proteins, Cry1Ac protein was the most toxic, followed by the Cry1Ab and Cry1Aa proteins. The Cry1Ca protein showed no toxicity. The Cry1Aa, Cry1Ab and Cry1Ac proteins showed specific binding to the midgut membrane receptors of H. armigera caterpillars. Heterologous competitive binding assays revealed that Cry1Aa, Cry1Ab, Cry1Ac compete for a common receptor in the midgut larvae<br>Mestre
9
Moragrega, i. Garcia Concepció. "Interacció Pseudomonas syringae pv. syringae-perera. Factors determinants i activitat de diversos fosfonats en el desenvolupament de la malaltia." Doctoral thesis, Universitat de Girona, 1997. http://hdl.handle.net/10803/96472.
Full textAbstract:
Blast of pear caused by Pseudomonas syringae pv. syringae is one of the bacterial disease that limit pear production throughout the world. Symptoms are characterized by blast of buds and blossoms wich causes significant loss of fruit production, and necrotic spots on leaves or fruits. Control of bacterial blast of pear with chemicals is difficult and is based on copper compounds and antibiontics. However, its use is limited by the low efficacy, phytotoxicity to the plant or emerging resistance of the pathogen. The activity of several phosphonates (fosetil-Al, potassium phosphonate, etephon and fosfomycin) for control of P. syringae pv. syringae infection on pear was determined in this work, and laboratory models for studying P. syringae pv. syringae-pear interaction were developed<br>Pseudomonas syringae pv. syringae és un bacteri que ha estat descrit com agent causant de diverses malalties en més de 200 especies vegetals. En perera causa la necrosi bacteriana, que afecta la majoria de zones productores de pera del món, provocant un debilitament dels arbres i una disminució de la productivitat. En el treball que es presenta s'ha determinat l’activitat de diversos fosfonats (fosetil-AI, fosfonat potàssic, etefon i fosfomicina) en el control de la infecció per P. syringae pv. syringae en perera. Per això s'han desenvolupat models d'estudi de la interacció P. syringae pv. Syringae-perera i s'han determinat els factors que afecten la interacció. Aquests models de laboratori, com que han permès conèixer aspectes concrets de la interacció hoste-patogen i definir de forma clara el tipus d'interacció, s'han aplicat a l'estudi de l'activitat dels fosfonats en la interacció P. syringae pv. syringae -perera i en el control de la malaltia
10
Kim, Min Jun. "Bacterial flows : mixing and pumping in microfluidic systems using flagellated bacteria /." View online version; access limited to Brown University users, 2005. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3174627.
Full textBooks on the topic "Bacterii"
2
Ernst, Joel D., and Olle Stendahl, eds. Phagocytosis of Bacteria and Bacterial Pathogenicity. Cambridge University Press, 2006. http://dx.doi.org/10.1017/cbo9780511541513.
Full text
3
D, Ernst Joel, and Stendahl Olle, eds. Phagocytosis of bacteria and bacterial pathogenicity. Cambridge University Press, 2006.
Find full text
4
J, Dring G., Gould G. W, Ellar D. J, Federation of European Microbiological Societies., Society for Applied Bacteriology, and International Symposium on "Fundamental and Applied Aspects of Bacterial Spores" (1982 : University of Cambridge), eds. Fundamental and applied aspects of bacterial spores. Academic Press, 1985.
Find full text
6
Marshall, William. Of microbes and men: The emotions, drama, and mystery of a struggle to correct a 125-year-old mistake and improve our defenses against epidemics and bioterrorism : a public affairs book. AuthorHouse, 2008.
Find full text
7
Marshall, William. Of microbes and men: The emotions, drama, and mystery of a struggle to correct a 125-year-old mistake and improve our defenses against epidemics and bioterrorism : a public affairs book. AuthorHouse, 2008.
Find full text
8
Marshall, William. Of microbes and men: The emotions, drama, and mystery of a struggle to correct a 125-year-old mistake and improve our defenses against epidemics and bioterrorism : a public affairs book. AuthorHouse, 2008.
Find full text
9
Wyatt, G. M. Immunoassays for Food-poisoning Bacteria and Bacterial Toxins. Springer US, 1992. http://dx.doi.org/10.1007/978-1-4615-2001-6.
Full text
10
A, Lee H., and Morgan M. R. A, eds. Immunoassays for food-poisoning bacteria and bacterial toxins. Chapman & Hall, 1992.
Find full textBook chapters on the topic "Bacterii"
1
Paterson, Jamie, Martín López-García, Joseph Gillard, Thomas R. Laws, Grant Lythe, and Carmen Molina-París. "Analysis of Single Bacterium Dynamics in a Stochastic Model of Toxin-Producing Bacteria." In Lecture Notes in Computer Science. Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-91825-5_13.
Full textAbstract:
AbstractWe stochastically model two bacterial populations which can produce toxins. We propose to analyse this biological system by following the dynamics of a single bacterium during its lifetime, as well as its progeny. We study the lifespan of a single bacterium, the number of divisions that this bacterium undergoes, and the number of toxin molecules that it produces during its lifetime. We also compute the mean number of bacteria in the genealogy of the original bacterium and the number of toxin molecules produced by its genealogy. We illustrate the applicability of our methods by considering the bacteria Bacillus anthracis and antibiotic treatment, making use of in vitro experimental data. We quantify, for the first time, bacterial toxin production by exploiting an in vitro assay for the A16R strain, and make use of the resulting parameterised model to illustrate our techniques.
2
Bährle-Rapp, Marina. "Bacterium (Plur. Bacteria)." In Springer Lexikon Kosmetik und Körperpflege. Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/978-3-540-71095-0_947.
Full text
3
Christensen, Henrik, and Werner Nicklas. "Bacteria and Bacterial Diagnostics." In Laboratory Animal Science and Medicine. Springer International Publishing, 2024. http://dx.doi.org/10.1007/978-3-031-59103-7_10.
Full text
4
Cerone, Antonio, and Enrico Marsili. "A Formal Model for the Simulation and Analysis of Early Biofilm Formation." In From Data to Models and Back. Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-70650-0_9.
Full textAbstract:
AbstractBiofilms are structured communities of bacterial cells adherent to a surface. This bacterial state is called sessile.This paper focuses on the modelling of the transition between planktonic and sessile state using Real-time Maude as the modelling language. With more and more bacteria joining the sessile community, the likelihood of producing a biofilm increases. Once the percentage of bacterial cells that adheres to the surface reaches a threshold, which is specific for the considered bacterium species, a permanent biofilm is formed. An important challenge is to predict the time needed for the formation of a biofilm on a specific surface, in order to plan when the material infrastructure that comprises such a surface needs to be cleaned or replaced. We exploit the model-checking features of Real-time Maude to formally prove that a regular cleaning or replacement of the infrastructure prevents the biofilm formation.
5
Gul Guven, Reyhan, and Kemal Guven. "Bacterial Toxins." In Food Safety. Nobel Tip Kitabevleri, 2024. http://dx.doi.org/10.69860/nobel.9786053358787.5.
Full textAbstract:
In the globalizing world, food safety and food-borne pathogenic microorganisms are among the important public health problems. There are more than 250 known foodborne diseases and many different types of viruses, bacteria, parasites, toxins, metals and prions that cause these diseases. Toxic molecules generated by bacteria, whether within or outside the organisms, are commonly referred to as "toxins". Toxins serve as the primary virulence factors generated by a multitude of bacteria responsible for causing severe illnesses in both humans and animals. Toxins are the primary bacterial component leading to health problems. This chapter provides information about bacterial toxins.
6
Cohan, Frederick M. "Genomes reveal the cohesiveness of bacterial species taxa and provide a path towards describing all of bacterial diversity." In Trends in the systematics of bacteria and fungi. CABI, 2021. http://dx.doi.org/10.1079/9781789244984.0282.
Full textAbstract:
Abstract This book chapter argues that bacterial systematists of the mid-20th century fortuitously created a species-level systematics that actually fits an important universal theory of speciation by discussing taxonomy would allow us to infer the important characteristics of any unknown organism once we classify it to species. It turns out, unexpectedly, that bacterial species taxa share a species-like property with the species taxa of zoology and botany. While recombination within species taxa of all these groups fails to prevent diversification within species, recombination nevertheless appears to act universally as a force of cohesion within species taxa. That is, recurrent recombination within species limits neutral sequence divergence within species taxa of plants, animals, and bacteria; recombination also allows a sharing of generally adaptive genes across a species range. The 95% ANI criterion that demarcates the traditionally defined species taxa of bacteria fortuitously also yields groups of bacteria that are subject to the species-like property of cohesion, where recombination prevents neutral sequence divergence among ecotypes within a species. Use of the ANI criterion, then, not only provides an easily used algorithm for demarcating bacterial species; it also places bacterial demarcation on the same theory-based foundation as the species taxonomy of animals and plants.
7
Lawley, Trevor, Brian M. Wilkins, and Laura S. Frost. "Bacterial Conjugation in Gram-Negative Bacteria." In Plasmid Biology. ASM Press, 2014. http://dx.doi.org/10.1128/9781555817732.ch9.
Full text
8
Mikulska, Malgorzata. "Neutropenic Fever." In The EBMT Handbook. Springer International Publishing, 2024. http://dx.doi.org/10.1007/978-3-031-44080-9_35.
Full textAbstract:
AbstractFever during neutropenia is almost universal after an HCT. In neutropenic HCT recipients, clinicians are faced with a unique combination of issues: (1) high incidence of bacterial bloodstream infections, (2) high mortality in case of infections due to Gram-negative bacteria unless effective antibiotic treatment is provided promptly, and (3) numerous causes of fever other than bacterial infection.
9
Malinowska, Agnes. "Bacteria." In Microbium. punctum books, 2023. http://dx.doi.org/10.53288/0396.1.04.
Full textAbstract:
Bacteria have played a truly outsized role in the evolutionary story of life on earth, and they continue to be crucial to sustaining organisms and ecosystems. Until recently, however, most cultural and scientific interest in bacteria has centered on defeating the nefarious “germ.” This entry focuses in particular on how public health efforts to reign in the threat of bacterial disease in the US around 1900 aligned with the aspirations of a hegemonic Anglo-American culture to control and suppress marginalized groups like immigrants and racial others, easy scapegoats for disease. At the same time, British settler colonialism and, eventually, US government policy catalyzed devastating epidemics amongst Indigenous populations from the colonial period into the twentieth century, such as the tuberculosis crisis in Native health. While bacterial disease has been largely divisive in the US, bacteria themselves can encourage humans to think in terms of cooperation and alliance, rather than the strict enforcement of borders. Both symbiosis—bacteria’s preferred social relation—and binary fission—bacterial reproduction—suggest a radical form of sociality that permeates, ruptures, and transforms “individuals” constantly, so that the one always slips into the collective.
10
Selim, Gulnihan, and Elif Ozlem Arslan Aydogdu. "Interconnection Between Antibiotic Resistance and Climate Change." In Ecological Dynamics in the Face of Climate Change. Nobel Tip Kitabevleri, 2024. http://dx.doi.org/10.69860/nobel.9786053359258.3.
Full textAbstract:
Antibiotic resistance is one of nowdays biggest public health problems. Because of their adaptation abilities, bacteria are gaining resistance against the antibiotics. When a bacterium resistance to antibiotic, it also cause resistance in other bacteria in its environment. Climate change causes antibacterial resistance to increase. Both increasing air temperatures and natural disasters resulting from climate change cause antibiotic resistance to increase. Increasing antibiotic resistance cause a serious danger to public health.
Conference papers on the topic "Bacterii"
1
Wan, C. K., Hongzhe Sun, and Ji-Dong Gu. "Surface Properties of Galvanized Metals and Attachment by the Bacterium Janthinobacterium Lividum." In CORROSION 2003. NACE International, 2003. https://doi.org/10.5006/c2003-03567.
Full textAbstract:
Abstract Atomic Force Microscopy (AFM) is a useful tool for characterizing material surface properties and studying in situ bacterial biofilms formed on metal surfaces. The aims of the present study were to evaluate metal surface roughness after a series of treatments and attachment of the bacterium Janthinobacterium lividum, isolated from a drinking-water catridge, and to establish the relationship between surface treatment and susceptibility to biofilm formation. The four metal coupons used included Al Galvanized 0.3%, 5%, 55% and a pure zinc plate. Our results showed that several roughness parameters including auto-covariance, Z-range, mean roughness and maximum height of the coupons increased with bacterial attachment on metal surfaces. There was a strong positive correlation between different roughness parameters and the number of bacteria attached on metal surfaces (r2, 0.807 to 0.900) in an incubation experiment conducted for 7 days. Highest number of bacteria on surface was observed on coupons of Al Galvanized 55%, the roughest surface among the test coupons. The numbers of bacterial cells on coupon surfaces examined by Scanning Electron Microscopy (SEM) were 1.02×105, 5.98×104, 3.14×104 and 1.07×104/mm2 for Al Galvanized 55%, 5%, 0.3% and pure zinc plate, respectively. Our data suggest that bacterial attachment on metal surfaces is strongly affected by surface morphological characteristics and modification of physical properties by surface treatment may decrease or increase the initial attachment by bacteria.
2
de Romero, Matilde F., Duque C. Zoilabet, Oladis T. de Rincón, Orlando Pérez, and Ismenia Araujo. "Hydrogen Permeation Study with Palladium in a Sulfate-Reducing Bacteria Culture." In CORROSION 2001. NACE International, 2001. https://doi.org/10.5006/c2001-01260.
Full textAbstract:
Abstract This study was undertaken to evaluate cathodic depolarization as the action mechanism triggered by sulfate-reducing bacterias (SRBs) in Microbiologically Induced Corrosion (MIC), using an inert substrate such as a 1-mm thick Palladium (Pd) strip with and without cathodic polarization, a H° permeation cell type by Devanathan and Stachurski, and the bacteria Desulfovibrio desulfuricans ssp. desulfuricans. The permeation tests were run using a de-aerated sterile culture medium inoculated with 10% D. desulfuricans at 108 cell/ml. Bacterial growth was evaluated by the serial dilution technique and Scanning Electron Microscopy (SEM) was used to analyze the characteristics of the biofilm formed on the Pd strip. Results indicated bacterial growth in the order of 40x109 CFU/ml at 24 hours in both polarization and non-polarization tests. This shows that these bacteria develop similarly, whether or not they are on a polarized surface as a source of H°, generating H2S as a product of sulfate-dissimilating activity. It was also determined that, without cathodic polarization, there were no conditions for reduction and permeation of the H+ generated by H2S dissociation. When cathodic polarization was applied, an increase was observed in the permeation current, which was associated with the maximum enzymatic activity phase of the bacteria.
3
Little, Brenda J., Richard I. Ray, Patricia A. Wagner, Joanne Jones-Meehan, C. C. Lee, and Florian Mansfeld. "Marine Bacteria and Localized Corrosion on Polymer Coated Steel: Cause and Effect." In CORROSION 1999. NACE International, 1999. https://doi.org/10.5006/c1999-99183.
Full textAbstract:
Abstract Diagnosis of microbiologically influenced corrosion on iron-containing substrata exposed in marine environments cannot be based solely on spatial relationships between large accumulations of bacterial cells and iron corrosion products. Field experiments were designed to evaluate the relationship between marine bacteria and localized corrosion on coated mild steel. In all cases, the distribution of bacteria was strongly influenced by the presence of iron corrosion products independent of coating combinations. In the presence of cathodic protection, coating defects were filled with calcareous deposits and few bacterial cells. Results demonstrate that bacteria are preferentially attracted to iron corrosion products in coating defects and that attraction is more influential than topography in determining the spatial distribution of bacterial cells.
4
Horacek, Gary. "Biocorrosion in the Oilfield I. Experimental Methods Development; Scanning Electron Microscopy Technique." In CORROSION 1988. NACE International, 1988. https://doi.org/10.5006/c1988-88086.
Full textAbstract:
Abstract Biocorrosion is routinely encountered, but not always recognized, in the oilfield. Biocorrosion results primarily from the activities of sessile (adherent) bacteria growing in biofilms on metal surfaces. Classical microbiological methods are not appropriate for detecting or monitoring sessile bacteria. In the work reported here, biofilming bacteria, their associated exopolymer, and the early time-course events of biofilm development on steel were visualized by use of the scanning electron microscope (SEM). Scanning electron photomicrographs also show that corrosion occurred directly under the bacterial growth. Prevention of bacterial growth prevented corrosion. These SEM results represent progress in developing technology useful for detecting and monitoring sessile bacteria and biocorrosion in the oilfield environment.
5
Little, Brenda J., Patricia A. Wagner, and Richard I. Ray. "An Experimental Evaluation of Titanium’S Resistance to Microbiologically Influenced Corrosion." In CORROSION 1992. NACE International, 1992. https://doi.org/10.5006/c1992-92173.
Full textAbstract:
Abstract The corrosion behavior of titanium and two stainless steels containing 6% molybdenum (AL6XN and SMO 254) was evaluated in extreme environments created by bacteria. Electrochemical parameters and surface chemistry were compared for grade 2 titanium, AL6XN and SMO 254 after exposure to natural seawater, to a pure culture of mesophilic (temperature range 25–40°C) bacterium capable of oxidizing both iron and sulfur, and to a mixed culture of mesophilic facultative bacteria containing sulfate-reducing bacteria (SRB). Titanium weld regions were evaluated for hydride formation after exposure to mesophilic hydrogen-producing bacteria. Titanium and AL6XN did not show localized corrosion under any of the exposure conditions. SMO 254 was deeply etched after 75 days in the medium containing the iron/sulfur oxidizing bacterium. Experiments with thermophilic (temperature range 60–80°C) sulfur oxidizing bacteria (SOB), SRB and hydrogen-producing bacteria are underway.
6
Blackburn, Freeman E. "Detection, Monitoring, and Control of Bacterial Corrosion in a Large Middle-East Oilfield Waterflood." In CORROSION 1985. NACE International, 1985. https://doi.org/10.5006/c1985-85289.
Full textAbstract:
Abstract Bacterial attack in anaerobic water systems can be rapid and still be difficult to detect as such. Operating experience from a large Middle East water flood covered some of the pitfalls in detecting, monitoring and controling bacterial corrosion. Initial failures to culture bacteria led to chemical treatments of the water which were ineffective and in one case detrimental to bacterial control. Early chemical biocide treatments were based on such indirect techniques as corrosion coupon appearance and water quality changes. Later, when the bacteria were sucessfully cultured, they were found throughout the system. For various reasons however, the presence of bacteria did not automatically lead to a corrosion problem. Experience with operating parameters and sources of reinfection aided the chemical treatment in overall corrosion control. The size and complexity of the waterflood provided a unique opportunity to examine biological corrosion with simular bacteria in the same water under a wide varity of conditions.
7
Campbell, Scott, Andrew Duggleby, and Angela Johnson. "Conventional Application of Biocides May Lead to Bacterial Cell Injury Rather than Bacterial Kill within a Biofilm." In CORROSION 2011. NACE International, 2011. https://doi.org/10.5006/c2011-11234.
Full textAbstract:
Abstract Mitigation of microbiological related problems, specifically, microbially influenced corrosion (MIC) is often mitigated utilizing biocides or biostatic chemicals. The use of the chemicals is often employed to control viable bacterial numbers, which would ultimately mitigate microbiological activity. However, after applying biocides for over 50 years within the petroleum industry, MIC is present and has been implicated in several critical failures. Although these failures still occur, no work has been done to establish and understand if current treatment regimes are ultimately mitigating MIC by controlling bacteria populations, specifically SRB’s within a biofilm. This paper reports the efficacy of biocides applied in a dynamic flow cell system evaluating current conventional treatment regimes decreasing viable bacterial numbers within a biofilm, and thus decreasing SRB activity. The data suggests that biocides may not be killing bacteria within a biofilm, and after further review of doubling times of SRB’s within the bacterial biofilm, suggests that bacterial cell injury may be a possible explanation rather than bacterial cell kill. Therefore, controlling MIC by applying biocides to simply kill bacteria may not be effective.
8
Fichter, Jennifer, Kenneth Wunch, Robert Moore, Elizabeth Summer, Shelby Braman, and Phineas Holmes. "How Hot Is Too Hot for Bacteria? a Technical Study Assessing Bacterial Establishment in Downhole Drilling, Fracturing and Stimulation Operations." In CORROSION 2012. NACE International, 2012. https://doi.org/10.5006/c2012-01310.
Full textAbstract:
Abstract Bacterial contamination from drilling and fracturing can lead to serious problems in unconventional oil and gas shale plays. Large water volumes for these processes are transported from aquifers, municipal waters, rivers, lakes, ponds or oilfield flowback water to the wellsite and stored in frac tanks or earthen impoundments. Typically, these waters are contaminated with bacteria. Furthermore, fracturing fluids contain gelling agents or polyacrylamide-based friction reducers which are readily available bacterial food sources. If these fluids are insufficiently treated, establishment of sulfate-reducing bacteria (SRB) and acid-producing bacteria (APB) can lead to operational issues including: 1) biogenic sulfide production and formation souring, 2) plugging from iron sulfide scale production, 3) microbially influenced corrosion (MIC), and 4) premature degradation of fracturing fluids. As operators have moved into hotter, deeper unconventional shale plays, the following question has been posed: “How hot is too hot for bacteria?” Downhole reservoir temperatures can approach 260 to 360°F (127 to 182°C), temperatures previously thought to be inhibitory to bacteria. Are introduced bacterial species capable of becoming established in these hot reservoirs following the drilling and fracturing processes? Does the nutrient influx from drilling and fracturing processes stimulate viable, indigenous bacteria? These are some of the key questions addressed in this study.
9
Shukla, Pavan K., Roderick E. Fuentes, Andrew Nordquist, Bruce J. Wiersma, and Ingrid Pederson. "Effectiveness of Vapor Corrosion Inhibitors under Bacterial Activity for Aboveground Storage Tank Application." In CONFERENCE 2024. AMPP, 2024. https://doi.org/10.5006/c2024-20789.
Full textAbstract:
Abstract Bacterial activity is known to influence corrosion and can result in increasing soil-side corrosion of the aboveground storage tanks (ASTs) floor plates. Association for Materials Protection and Performance (AMPP) defines this phenomenon as Microbiologically Influenced Corrosion (MIC). It has been hypothesized that vapor corrosion inhibitors (VCIs) can not only function in presence of bacterial activity but can also function as biocides. Experiments were conducted to study the effect of bacterial activity on corrosion in the sand pad conditions and effect of VCIs in mitigating MIC. Various bacteria cultures were grown using commercially available culture media, and coupon exposure tests were performed with field sand mixed with the culture media. To this end, control and VCI-dosed electrolytes were prepared using the field sand plus bacteria cultures. Pre- and post-test bacteria concentration estimation and measurements, respectively, in the VCI-dosed electrolytes indicated that VCIs do not function as biocides, however, VCIs are highly effective for mitigating corrosion in presence of bacterial activity.
10
Franklin, Michael J., James B. Guckert, David C. White, and Hugh S. Isaacs. "Spatial and Temporal Relationships between Localized Microbial Metabolic Activity and Electrochemical Activity of Steel." In CORROSION 1991. NACE International, 1991. https://doi.org/10.5006/c1991-91115.
Full textAbstract:
Abstract The relationship between the localized microbial activity and localized electrochemical on corroding steel surfaces was investigated. The scanning vibrating electrode technique provided a sensitive means for defining local anodic and cathodic currents associated with corrosion. Localized bacterial metabolic activity was determined using autoradiography of bacterial incorporated 14C-acetate into insoluble cell material. Microautoradiography of individual bacteria, with the incorporated acetate, was used to determine percentages and morphological types of active bacteria. The results showed a correlation between the location of anodic activity of the steel and the location of incorporated label. Although the results do not necessarily indicate a role for bacterial activity in the initiation of pitting, the results suggest that the actively metabolizing bacteria may exacerbate the propagation of pits by colonizing active anodic sites.
Reports on the topic "Bacterii"
1
Lindow, Steven, Isaac Barash, and Shulamit Manulis. Relationship of Genes Conferring Epiphytic Fitness and Internal Multiplication in Plants in Erwinia herbicola. United States Department of Agriculture, 2000. http://dx.doi.org/10.32747/2000.7573065.bard.
Full textAbstract:
Most bacterial plant pathogens colonize the surface of healthy plants as epiphytes before colonizing internally and initiating disease. The epiphytic phase of these pathogens is thus an important aspect of their epidemiology and a stage at which chemical and biological control is aimed. However, little is known of the genes and phenotypes that contribute to the ability of bacteria to grow on leaves and survive the variable physical environment in this habitat. In addition, while genes such as hrp awr and others which confer pathogenicity and in planta growth ability have been described, their contribution to other aspects of bacterial epidemiology such as epiphytic fitness have not been addressed. We hypothesized that bacterial genes conferring virulence or pathogenicity to plants also contribute to the epiphytic fitness of these bacteria and that many of these genes are preferentially located on plasmids. We addressed these hypotheses by independently identifying genes that contribute to epiphytic fitness, in planta growth, virulence and pathogenicity in the phytopathogenic bacterium Erwinia herbicola pv gypsophilae which causes gall formation on gypsophila. This species is highly epiphytically fit and has acquired a plasmid (pPATH) that contains numerous pathogenicity and virulence determinants, which we have found to also contribute to epiphytic fitness. We performed saturation transposon mutagenesis on pPATH as well as of the chromosome of E.h. gypsophilae, and identified mutants with reduced ability to grow in plants and/or cause disease symptoms, and through a novel competition assay, identified mutants less able to grow or survive on leaves. The number and identity of plasmid-borne hrp genes required for virulence was determined from an analysis of pPATH mutants, and the functional role of these genes in virulence was demonstrated. Likewise, other pPATH-encoded genes involved in IAA and cytokinin biosynthesis were characterized and their pattern of transcriptional activity was determined in planta. In both cases these genes involved in virulence were found to be induced in plant apoplasts. About half of avirulent mutants in pPATH were also epiphytically unfit whereas only about 10% of chromosomal mutants that were avirulent also had reduced epiphytic fitness. About 18% of random mutants in pPATH were avirulent in contrast to only 2.5% of random chromosomal mutants. Importantly, as many as 28% of pPATH mutants had lower epiphytic fitness while only about 10% of random chromosomal mutants had lower epiphytic fitness. These results support both of our original hypotheses, and indicate that genes important in a variety of interactions with plant have been enriched on mobile plasmids such as pPATH. The results also suggest that the ability of bacteria to colonize the surface of plants and to initiate infections in the interior of plants involves many of the same traits. These traits also appear to be under strong regulatory control, being expressed in response to the plant environment in many cases. It may be possible to alter the pattern of expression of such genes by altering the chemical environment of plants either by genetic means or by additional or chemical antagonists of the plant signals. The many novel bacterial genes identified in this study that are involved in plant interactions should be useful in further understanding of bacterial plant interactions.
2
Randall, Luke. - EU Harmonised Surveillance of Antimicrobial Resistance (AMR) in E. coli from Retail Meats in UK (2020 - Year 6, chicken). Food Standards Agency, 2021. http://dx.doi.org/10.46756/sci.fsa.phi798.
Full textAbstract:
In accordance with European Directive 2003/99/EC on the monitoring of bacteria that can pass from animals to humans and cause disease, Member States are obliged to ensure that procedures are in place to monitor and report on the occurrence of antimicrobial resistance (AMR) in such bacteria. The UK continued to be subject to EU rules during the transition period up to the end of December 2020. The requirements state that 300 retail chicken meats should be tested by culture for the bacterium Escherichia coli. E. coli bacteria are a normal part of the gut flora of mammals and as such can be useful “indicators” of AMR in gut bacteria. Whilst some strains of E. coli can cause disease, most strains of E. coli do not cause observable disease in healthy animals and humans. Addressing the public health threat posed by AMR is a national strategic priority for the UK, which has led to both a 20-year vision of AMR (Opens in a new window)and a 5-year (2019 to 2024) AMR National Action Plan (NAP)
3
Goddard, Alan, and Rachel Pateman. Exploring the chopping board microbiome – lessons learned. Food Standards Agency, 2023. http://dx.doi.org/10.46756/sci.fsa.eaf949.
Full textAbstract:
Household surfaces are a well-known source of bacterial contamination, with ~40% of outbreaks of foodborne infections in Europe occurring at home. Whilst disease-causing bacteria may arrive in the home in contaminated food, it is also likely that many disease outbreaks are caused by poor hygiene and cross-contamination from raw food. A key site of such microbial contamination is chopping boards.
4
Wilde, E. W., J. C. Radway, T. C. Hazen, and P. Hermann. Immobilization of degradative bacteria in polyurethane-based foams: embedding efficiency and effect on bacterial activity. Office of Scientific and Technical Information (OSTI), 1996. http://dx.doi.org/10.2172/565240.
Full text
5
Torrungruang, Kitti, and Suchada Chutimawarapun. Antimicrobial activity against periodontopathic bacteria, cell toxicity against gingival fibroblasts and antinflammatory effect of crude extract from mangosteen. Chulalongkorn University, 2006. https://doi.org/10.58837/chula.res.2006.15.
Full textAbstract:
Extract from mangosteen pericarp has demonstrated various pharmacological activities including anti-bacterial, anti-inflammatory and anti-fungal. It may have potential for the treatment of periodontal disease, which is a chronic inflammatory disease caused by anaerobic bacteria. The aim of this study was 1) to investigate the toxicity of mangosteen extract to human gingival fibroblast, 2) to examine the anti-bacterial activity of the extract against periodontopathic bacteria including P. gingivalis and A. actinomycetemcomitans, and 3) to examine the inhibitory effect of the extract on PGE[subscript2]) production in lipopolysaccharide (LPS)-activated peripheral blood monocytes. The changes in cell viability were observed by inverted phase contrast microscopy and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenytetrazolium bromide (MTT) assay. The extract was not toxic when exposed to fibroblasts for up to 48 hours at the concentration of 200 [M]g/ml or less. The extract exhibited anti-bacterial activity against P. gingivalis, but not A. actinomycetemcomitans. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against P. gingivalis were 20 and 40 [M]g/ml, respectively. The anti-inflammatory activity of the extract was determined by measuring PGE[subscript2] production with enzyme-linked immunosorbent assy (ELISA). The extract significantly inhibited LPS-induced PGE production in a dose-dependent manner. Its inhibitory effect reached maximal level at 10 [M]g/ml. These results suggest that the extract from mangosteen pericarp may be beneficial for periodontal treatment.
6
Gottlieb, Yuval, Bradley Mullens, and Richard Stouthamer. investigation of the role of bacterial symbionts in regulating the biology and vector competence of Culicoides vectors of animal viruses. United States Department of Agriculture, 2015. http://dx.doi.org/10.32747/2015.7699865.bard.
Full textAbstract:
Symbiotic bacteria have been shown to influence host reproduction and defense against biotic and abiotic stressors, and this relates to possible development of a symbiont-based control strategy. This project was based on the hypothesis that symbionts have a significant impact on Culicoides fitness and vector competence for animal viruses. The original objectives in our proposal were: 1. Molecular identification and localization of the newly-discovered symbiotic bacteria within C. imicola and C. schultzei in Israel and C. sonorensis in California. 2. Determination of the prevalence of symbiotic bacteria within different vector Culicoides populations. 3. Documentation of specific symbiont effects on vector reproduction and defense: 3a) test for cytoplasmic incompatibility in Cardinium-infected species; 3b) experimentally evaluate the role of the symbiont on infection or parasitism by key Culicoides natural enemies (iridescent virus and mermithid nematode). 4. Testing the role(s) of the symbionts in possible protection against infection of vector Culicoides by BTV. According to preliminary findings and difficulties in performing experimental procedures performed in other insect symbiosis systems where insect host cultures are easily maintained, we modified the last two objectives as follows: Obj. 3, we tested how symbionts affected general fitness of Israeli Culicoides species, and thoroughly described and evaluated the correlation between American Culicoides and their bacterial communities in the field. We also tried alternative methods to test symbiont-Culicoides interactions and launched studies to characterize low-temperature stress tolerances of the main US vector, which may be related to symbionts. Obj. 4, we tested the correlation between EHDV (instead of BTV) aquisition and Cardinium infection. Culicoides-bornearboviral diseases are emerging or re-emerging worldwide, causing direct and indirect economic losses as well as reduction in animal welfare. One novel strategy to reduce insects’ vectorial capacity is by manipulating specific symbionts to affect vector fitness or performance of the disease agent within. Little was known on the bacterial tenants occupying various Culicoides species, and thus, this project was initiated with the above aims. During this project, we were able to describe the symbiont Cardinium and whole bacterial communities in Israeli and American Culicoides species respectively. We showed that Cardinium infection prevalence is determined by land surface temperature, and this may be important to the larval stage. We also showed no patent significant effect of Cardinium on adult fitness parameters. We showed that the bacterial community in C. sonorensis varies significantly with the host’s developmental stage, but it varies little across multiple wastewater pond environments. This may indicate some specific biological interactions and allowed us to describe a “core microbiome” for C. sonorensis. The final set of analyses that include habitat sample is currently done, in order to separate the more intimately-associated bacteria from those inhabiting the gut contents or cuticle surface (which also could be important). We were also able to carefully study other biological aspects of Culicoides and were able to discriminate two species in C. schultzei group in Israel, and to investigate low temperature tolerances of C. sonorensis that may be related to symbionts. Scientific implications include the establishment of bacterial identification and interactions in Culicoides (our work is cited in other bacteria-Culicoides studies), the development molecular identification of C. schultzei group, and the detailed description of the microbiome of the immature and matched adult stages of C. sonorensis. Agricultural implications include understanding of intrinsic factors that govern Culicoides biology and population regulation, which may be relevant for vector control or reduction in pathogen transmission. Being able to precisely identify Culicoides species is central to understanding Culicoides borne disease epidemiology.
7
Splitter, Gary, and Menachem Banai. Microarray Analysis of Brucella melitensis Pathogenesis. United States Department of Agriculture, 2006. http://dx.doi.org/10.32747/2006.7709884.bard.
Full textAbstract:
Original Objectives 1. To determine the Brucella genes that lead to chronic macrophage infection. 2. To identify Brucella genes that contribute to infection. 3. To confirm the importance of Brucella genes in macrophages and placental cells by mutational analysis. Background Brucella spp. is a Gram-negative facultative intracellular bacterium that infects ruminants causing abortion or birth of severely debilitated animals. Brucellosis continues in Israel, caused by B. melitensis despite an intensive eradication campaign. Problems with the Rev1 vaccine emphasize the need for a greater understanding of Brucella pathogenesis that could improve vaccine designs. Virulent Brucella has developed a successful strategy for survival in its host and transmission to other hosts. To invade the host, virulent Brucella establishes an intracellular niche within macrophages avoiding macrophage killing, ensuring its long-term survival. Then, to exit the host, Brucella uses placenta where it replicates to high numbers resulting in abortion. Also, Brucella traffics to the mammary gland where it is secreted in milk. Missing from our understanding of brucellosis is the surprisingly lillie basic information detailing the mechanisms that permit bacterial persistence in infected macrophages (chronic infection) and dissemination to other animals from infected placental cells and milk (acute infection). Microarray analysis is a powerful approach to determine global gene expression in bacteria. The close genomic similarities of Brucella species and our recent comparative genomic studies of Brucella species using our B. melitensis microarray, suqqests that the data obtained from studying B. melitensis 16M would enable understanding the pathogenicity of other Brucella organisms, particularly the diverse B. melitensis variants that confound Brucella eradication in Israel. Conclusions Results from our BARD studies have identified previously unknown mechanisms of Brucella melitensis pathogenesis- i.e., response to blue light, quorum sensing, second messenger signaling by cyclic di-GMP, the importance of genomic island 2 for lipopolysaccharide in the outer bacterial membrane, and the role of a TIR domain containing protein that mimics a host intracellular signaling molecule. Each one of these pathogenic mechanisms offers major steps in our understanding of Brucella pathogenesis. Strikingly, our molecular results have correlated well to the pathognomonic profile of the disease. We have shown that infected cattle do not elicit antibodies to the organisms at the onset of infection, in correlation to the stealth pathogenesis shown by a molecular approach. Moreover, our field studies have shown that Brucella exploit this time frame to transmit in nature by synchronizing their life cycle to the gestation cycle of their host succumbing to abortion in the last trimester of pregnancy that spreads massive numbers of organisms in the environment. Knowing the bacterial mechanisms that contribute to the virulence of Brucella in its host has initiated the agricultural opportunities for developing new vaccines and diagnostic assays as well as improving control and eradication campaigns based on herd management and linking diagnosis to the pregnancy status of the animals. Scientific and Agricultural Implications Our BARD funded studies have revealed important Brucella virulence mechanisms of pathogenesis. Our publication in Science has identified a highly novel concept where Brucella utilizes blue light to increase its virulence similar to some plant bacterial pathogens. Further, our studies have revealed bacterial second messengers that regulate virulence, quorum sensing mechanisms permitting bacteria to evaluate their environment, and a genomic island that controls synthesis of its lipopolysaccharide surface. Discussions are ongoing with a vaccine company for application of this genomic island knowledge in a Brucella vaccine by the U.S. lab. Also, our new technology of bioengineering bioluminescent Brucella has resulted in a spin-off application for diagnosis of Brucella infected animals by the Israeli lab by prioritizing bacterial diagnosis over serological diagnosis.
8
Yedidia, I., H. Senderowitz, and A. O. Charkowski. Small molecule cocktails designed to impair virulence targets in soft rot Erwinias. United States-Israel Binational Agricultural Research and Development Fund, 2020. http://dx.doi.org/10.32747/2020.8134165.bard.
Full textAbstract:
Chemical signaling between beneficial or pathogenic bacteria and plants is a central factor in determining the outcome of plant-microbe interactions. Pectobacterium and Dickeya (soft rot Erwinias) are the major cause of soft rot, stem rot, and blackleg formed on potato and ornamentals, currently with no effective control. Our major aim was to establish and study specific bacterial genes/proteins as targets for anti-virulence compounds, by combining drug design tools and bioinformatics with experimental work. The approach allowed us to identify and test compounds (small molecules) that specifically interfere with the activities of these targets, by this impairing bacterial virulence. Two main targets were selected within the frame of the BARD project. The first is the ATP-binding cassette (ABC) transporters and methyl-accepting chemotaxis proteins (MCP) that have been characterized here for the first time in Pectobacteriaceae, and the second is the quorum sensing (QS) machinery of Pectobacterium with its major proteins and in particular, the AHL synthase ExpI that was identified as the preferred target for inhibition. Both systems are strongly associated with bacterial virulence and survival in planta. We found that Pectobacteriaceae, namely Dickeya and Pectobacterium, encode more ABC transporters and MCP in their genomes, compared to other bacteria in the order. For MCP, soft rot Pectobacteriaceae not only contain more than 30 MCP genes per strain, but also have more diverse ligand binding domains than other species in the Enterobacteriales. These findings suggest that both ABC transporters and MCP are important for soft rot Pectobacteriaceae pathogenicity. We now have a selection of mutants in these proteins that may be further explored to understand their direct involvement in virulence. In parallel, we studied the QS central proteins in pectobacteria, the signaling molecule N-acyl-homoserine lactone synthase, ExpI, and the response regulator ExpR, and established their phylogenetic relations within plant pathogenic Gram negative bacteria. Next, these proteins were used for virtual screening of millions of compounds in order to discover new compounds with potential to interfere with the QS machinery. Several natural compounds were tested for their interference with virulence related traits in Pectobacterium and their capability to minimize soft rot infections. Our findings using microcalorimetric binding studies have established for the first time direct interaction between the protein ExpI and two natural ligands, the plant hormone salicylic acid and the volatile compound carvacrol. These results supported a model by which plants interfere with bacterial communication through interkingdom signaling. The collaborative project yielded two research papers and a comprehensive review, which included new computational and bioinformatics data, in Annu. Rev. Phytopathol., the highest ranked journal in phytopathology. Additional two papers are in preparation. In order to transform the fundamental knowledge that have been gained during this collaborative BARD project into agricultural practice, to control soft rot bacteria, we have submitted a continual project.
9
Beveridge, Terrance J. Composition, Reactivity and Regulation of Extracellular Metal-Reducing Structures (Bacterial Nanowires) Produced by Dissimilatory Metal - Reducing Bacteria. Office of Scientific and Technical Information (OSTI), 2004. http://dx.doi.org/10.2172/893692.
Full text
10
Scholten, Johannes. Composition, Reactivity, and Regulations of Extracellular Metal-Reducing Structures (Bacterial Nanowires) Produced by Dissimilatory Metal Reducing Bacteria. Office of Scientific and Technical Information (OSTI), 2006. http://dx.doi.org/10.2172/895881.
Full text