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Littérature scientifique sur le sujet « Bacterial biofilms »

Auteur : Grafiati

Publié le 4 juin 2021

Mis à jour le 12 juin 2025

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Articles de revues sur le sujet "Bacterial biofilms"

Tran, Hoai My, Hien Tran, Marsilea A. Booth, et al. "Nanomaterials for Treating Bacterial Biofilms on Implantable Medical Devices." Nanomaterials 10, no. 11 (2020): 2253. http://dx.doi.org/10.3390/nano10112253.

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Bacterial biofilms are involved in most device-associated infections and remain a challenge for modern medicine. One major approach to addressing this problem is to prevent the formation of biofilms using novel antimicrobial materials, device surface modification or local drug delivery; however, successful preventive measures are still extremely limited. The other approach is concerned with treating biofilms that have already formed on the devices; this approach is the focus of our manuscript. Treating biofilms associated with medical devices has unique challenges due to the biofilm’s extracellular polymer substance (EPS) and the biofilm bacteria’s resistance to most conventional antimicrobial agents. The treatment is further complicated by the fact that the treatment must be suitable for applying on devices surrounded by host tissue in many cases. Nanomaterials have been extensively investigated for preventing biofilm formation on medical devices, yet their applications in treating bacterial biofilm remains to be further investigated due to the fact that treating the biofilm bacteria and destroying the EPS are much more challenging than preventing adhesion of planktonic bacteria or inhibiting their surface colonization. In this highly focused review, we examined only studies that demonstrated successful EPS destruction and biofilm bacteria killing and provided in-depth description of the nanomaterials and the biofilm eradication efficacy, followed by discussion of key issues in this topic and suggestion for future development.

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Kvist, Malin, Viktoria Hancock, and Per Klemm. "Inactivation of Efflux Pumps Abolishes Bacterial Biofilm Formation." Applied and Environmental Microbiology 74, no. 23 (2008): 7376–82. http://dx.doi.org/10.1128/aem.01310-08.

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ABSTRACT Bacterial biofilms cause numerous problems in health care and industry; notably, biofilms are associated with a large number of infections. Biofilm-dwelling bacteria are particularly resistant to antibiotics, making it hard to eradicate biofilm-associated infections. Bacteria rely on efflux pumps to get rid of toxic substances. We discovered that efflux pumps are highly active in bacterial biofilms, thus making efflux pumps attractive targets for antibiofilm measures. A number of efflux pump inhibitors (EPIs) are known. EPIs were shown to reduce biofilm formation, and in combination they could abolish biofilm formation completely. Also, EPIs were able to block the antibiotic tolerance of biofilms. The results of this feasibility study might pave the way for new treatments for biofilm-related infections and may be exploited for prevention of biofilms in general.

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Hänsch, Gertrud Maria. "Host Defence against Bacterial Biofilms: “Mission Impossible”?" ISRN Immunology 2012 (November 5, 2012): 1–17. http://dx.doi.org/10.5402/2012/853123.

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Bacteria living as biofilms have been recognised as the ultimate cause of persistent and destructive inflammatory processes. Biofilm formation is a well-organised, genetically-driven process, which is well characterised for numerous bacteria species. In contrast, the host response to bacterial biofilms is less well analysed, and there is the general believe that bacteria in biofilms escape recognition or eradication by the immune defence. In this review the host response to bacterial biofilms is discussed with particular focus on the role of neutrophils because these phagocytic cells are the first to infiltrate areas of bacterial infection, and because neutrophils are equipped with a wide arsenal of bactericidal and toxic entities. I come to the conclusion that bacterial biofilms are not inherently protected against the attack by neutrophils, but that control of biofilm formation is possible depending on a timely and sufficient host response.

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Peng, Qi, Xiaohua Tang, Wanyang Dong, Ning Sun, and Wenchang Yuan. "A Review of Biofilm Formation of Staphylococcus aureus and Its Regulation Mechanism." Antibiotics 12, no. 1 (2022): 12. http://dx.doi.org/10.3390/antibiotics12010012.

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Bacteria can form biofilms in natural and clinical environments on both biotic and abiotic surfaces. The bacterial aggregates embedded in biofilms are formed by their own produced extracellular matrix. Staphylococcus aureus (S. aureus) is one of the most common pathogens of biofilm infections. The formation of biofilm can protect bacteria from being attacked by the host immune system and antibiotics and thus bacteria can be persistent against external challenges. Therefore, clinical treatments for biofilm infections are currently encountering difficulty. To address this critical challenge, a new and effective treatment method needs to be developed. A comprehensive understanding of bacterial biofilm formation and regulation mechanisms may provide meaningful insights against antibiotic resistance due to bacterial biofilms. In this review, we discuss an overview of S. aureus biofilms including the formation process, structural and functional properties of biofilm matrix, and the mechanism regulating biofilm formation.

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Masi, Elisa, Marzena Ciszak, Luisa Santopolo, et al. "Electrical spiking in bacterial biofilms." Journal of The Royal Society Interface 12, no. 102 (2015): 20141036. http://dx.doi.org/10.1098/rsif.2014.1036.

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In nature, biofilms are the most common form of bacterial growth. In biofilms, bacteria display coordinated behaviour to perform specific functions. Here, we investigated electrical signalling as a possible driver in biofilm sociobiology. Using a multi-electrode array system that enables high spatio-temporal resolution, we studied the electrical activity in two biofilm-forming strains and one non-biofilm-forming strain. The action potential rates monitored during biofilm-forming bacterial growth exhibited a one-peak maximum with a long tail, corresponding to the highest biofilm development. This peak was not observed for the non-biofilm-forming strain, demonstrating that the intensity of the electrical activity was not linearly related to the bacterial density, but was instead correlated with biofilm formation. Results obtained indicate that the analysis of the spatio-temporal electrical activity of bacteria during biofilm formation can open a new frontier in the study of the emergence of collective microbial behaviour.

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Ferguson, Berrylin J., and Donna B. Stolz. "Demonstration of Biofilm in Human Bacterial Chronic Rhinosinusitis." American Journal of Rhinology 19, no. 5 (2005): 452–57. http://dx.doi.org/10.1177/194589240501900506.

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Background Bacterial biofilms may explain why some patients with bacterial chronic rhinosinusitis (CRS) improve while on antibiotics but relapse after completion of the antibiotic. In the human host, biofilms exist as a community of bacteria surrounded by a glycocalyx that is adherent to a foreign body or a mucosal surface with impaired host defense. Biofilms generate planktonic, nonadherent bacterial forms that may metastasize infection and generate systemic illness. These planktonic bacteria are susceptible to antibiotics, unlike the adherent biofilm. Methods We reviewed four cases of CRS using transmission electron microscopy (TEM) to assay for typical colony architecture of biofilms. Bacterial communities surrounded by a glycocalyx of inert cellular membrane materials consistent with a biofilm were shown in two patients. Results In the two patients without biofilm, a nonbacterial etiology was discovered (allergic fungal sinusitis) in one and in the other there was scant anaerobic growth on culture and the Gram stain was negative. Culture of the material from the biofilm grew Pseudomonas aeruginosa in both patients. Pseudomonas from the biofilm showed a glycocalyx, not present in Pseudomonas cultured for 72 hours on culture media. Both patients’ symptoms with bacterial biofilms were refractory to culture-directed antibiotics, topical steroids, and nasal lavages. Surgery resulted in cure or significant improvement. Conclusion Biofilms are refractory to antibiotics and often only cured by mechanical debridement. We believe this is the first TEM documentation of bacterial biofilms in CRS in humans.

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Nesse, Live L., Ane Mohr Osland, and Lene K. Vestby. "The Role of Biofilms in the Pathogenesis of Animal Bacterial Infections." Microorganisms 11, no. 3 (2023): 608. http://dx.doi.org/10.3390/microorganisms11030608.

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Biofilms are bacterial aggregates embedded in a self-produced, protective matrix. The biofilm lifestyle offers resilience to external threats such as the immune system, antimicrobials, and other treatments. It is therefore not surprising that biofilms have been observed to be present in a number of bacterial infections. This review describes biofilm-associated bacterial infections in most body systems of husbandry animals, including fish, as well as in sport and companion animals. The biofilms have been observed in the auditory, cardiovascular, central nervous, digestive, integumentary, reproductive, respiratory, urinary, and visual system. A number of potential roles that biofilms can play in disease pathogenesis are also described. Biofilms can induce or regulate local inflammation. For some bacterial species, biofilms appear to facilitate intracellular invasion. Biofilms can also obstruct the healing process by acting as a physical barrier. The long-term protection of bacteria in biofilms can contribute to chronic subclinical infections, Furthermore, a biofilm already present may be used by other pathogens to avoid elimination by the immune system. This review shows the importance of acknowledging the role of biofilms in animal bacterial infections, as this influences both diagnostic procedures and treatment.

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Jacques, Mario, Virginia Aragon, and Yannick D. N. Tremblay. "Biofilm formation in bacterial pathogens of veterinary importance." Animal Health Research Reviews 11, no. 2 (2010): 97–121. http://dx.doi.org/10.1017/s1466252310000149.

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AbstractBacterial biofilms are structured communities of bacterial cells enclosed in a self-produced polymer matrix that is attached to a surface. Biofilms protect and allow bacteria to survive and thrive in hostile environments. Bacteria within biofilms can withstand host immune responses, and are much less susceptible to antibiotics and disinfectants when compared with their planktonic counterparts. The ability to form biofilms is now considered a universal attribute of micro-organisms. Diseases associated with biofilms require novel methods for their prevention, diagnosis and treatment; this is largely due to the properties of biofilms. Surprisingly, biofilm formation by bacterial pathogens of veterinary importance has received relatively little attention. Here, we review the current knowledge of bacterial biofilms as well as studies performed on animal pathogens.

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Noguchi, Nobuo, Yuichiro Noiri, Masahiro Narimatsu, and Shigeyuki Ebisu. "Identification and Localization of Extraradicular Biofilm-Forming Bacteria Associated with Refractory Endodontic Pathogens." Applied and Environmental Microbiology 71, no. 12 (2005): 8738–43. http://dx.doi.org/10.1128/aem.71.12.8738-8743.2005.

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ABSTRACT Bacterial biofilms have been found to develop on root surfaces outside the apical foramen and be associated with refractory periapical periodontitis. However, it is unknown which bacterial species form extraradicular biofilms. The present study aimed to investigate the identity and localization of bacteria in human extraradicular biofilms. Twenty extraradicular biofilms, used to identify bacteria using a PCR-based 16S rRNA gene assay, and seven root-tips, used to observe immunohistochemical localization of three selected bacterial species, were taken from 27 patients with refractory periapical periodontitis. Bacterial DNA was detected from 14 of the 20 samples, and 113 bacterial species were isolated. Fusobacterium nucleatum (14 of 14), Porphyromonas gingivalis (12 of 14), and Tannellera forsythensis (8 of 14) were frequently detected. Unidentified and uncultured bacterial DNA was also detected in 11 of the 14 samples in which DNA was detected. In the biofilms, P. gingivalis was immunohistochemically detected in all parts of the extraradicular biofilms. Positive reactions to anti-F. nucleatum and anti-T. forsythensis sera were found at specific portions of the biofilm. These findings suggested that P. gingivalis, T. forsythensis, and F. nucleatum were associated with extraradicular biofilm formation and refractory periapical periodontitis.

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Liu, Siyu, Hongyun Lu, Shengliang Zhang, Ying Shi, and Qihe Chen. "Phages against Pathogenic Bacterial Biofilms and Biofilm-Based Infections: A Review." Pharmaceutics 14, no. 2 (2022): 427. http://dx.doi.org/10.3390/pharmaceutics14020427.

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Bacterial biofilms formed by pathogens are known to be hundreds of times more resistant to antimicrobial agents than planktonic cells, making it extremely difficult to cure biofilm-based infections despite the use of antibiotics, which poses a serious threat to human health. Therefore, there is an urgent need to develop promising alternative antimicrobial therapies to reduce the burden of drug-resistant bacterial infections caused by biofilms. As natural enemies of bacteria, bacteriophages (phages) have the advantages of high specificity, safety and non-toxicity, and possess great potential in the defense and removal of pathogenic bacterial biofilms, which are considered to be alternatives to treat bacterial diseases. This work mainly reviews the composition, structure and formation process of bacterial biofilms, briefly discusses the interaction between phages and biofilms, and summarizes several strategies based on phages and their derivatives against biofilms and drug-resistant bacterial infections caused by biofilms, serving the purpose of developing novel, safe and effective treatment methods against biofilm-based infections and promoting the application of phages in maintaining human health.

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Thèses sur le sujet "Bacterial biofilms"

Hughes, Kevin A. "Bacterial biofilms and their exopolysaccharides." Thesis, University of Edinburgh, 1997. http://hdl.handle.net/1842/15053.

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Bacterial biofilms are formed when bacteria in a liquid environment adhere to a surface, multiply to form microcolonies and synthesis a protective glycocalyx composed mainly of hydrated exopolysaccharide (EPS). Bacterial biofilms form in natural, medical and industrial environments and are usually highly heterogeneous. Biofilms can be single or multi-species and their characteristics are dictated by the environment in which they develop. The biofilm bacteria analysed were isolated from a factory environment and all were members of the Enterobacteriaceae. The composition of their extracellular polysaccharides was examined using standard biochemical assays, HPLC and paper chromatography. Most were anionic due to uronic acids, except for the EPS of two strains, 53b and Ent (both Enterobacter agglomerans), which contained only neutral sugars and were highly insoluble. Periodate oxidation revealed a high degree of 1→3 linkages. Bacteriophages which possessed polysaccharide depolymerase enzymes specific for the EPS of strains 53b and Ent were isolated from sewage from a number of sources. The glycanase of one phage (SF153b) was highly specific, had optima over a wide range of temperature and pH, and activity was increased by Ca²⁺ ions. Degradation of 53b and Ent EPS by the depolymerase produced oligosaccharide repeat units. HPLC and size exclusion chromatography gave an estimation of DP for 53b and Ent repeat units of 8-9 and 7-8 respectively. Polysaccharide samples derived from 53b biofilm and planktonic cells were both degraded by the same phage glycanase suggesting that biofilm formation does not stimulate production of a biofilm specific EPS.

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Wang, Anqi. "Bacterial biofilms and biomineralisation on titanium." Thesis, University of Birmingham, 2011. http://etheses.bham.ac.uk//id/eprint/1562/.

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This study investigated bacterial interactions with titanium, and evaluated the use of Serratia biomineralisation to produce a hydroxyapatite (HA) coating on titanium. Adherence of Gram-positive Staphylococcus epidermidis and Streptococcus sanguinis and Gram-negative Serratia sp. NCIMB 40259 and Escherichia coli was compared on commercially pure titanium, Ti6Al4V alloy, pure aluminium and pure vanadium. Grain boundaries, grain orientation and alloy phase structure did not influence adhesion or early proliferation. Adherence of all four strains was equivalent on pure titanium and Ti6Al4V and inhibited on pure aluminium. Serratia biomineralisation was used to introduce a crystalline coating on Al\(_2\)O\(_3\) grit blasted titanium discs and a porous titanium mesh. The porous coating consisted of micro-scale spheres composed of nano-scale calcium deficient HA. Embedded alumina particles and alkali treatment did not noticeably alter precipitation of Serratia HA, nor the structure of the coating in comparison with non-treated substrates. Coatings were retained after sintering at 800\(^\circ\)C in argon, although the original curved plate-like crystals changed to nano-scale β-tricalcium phosphate particles. A phosphorous-rich diffusion zone formed at the coating-titanium interface. This biomineralised coating may have applications for coatings of implants in non load-bearing sites, and other non-clinical applications where a high surface area is the major concern.

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Leiman, Sara. "Genetics and Regulation of Bacterial Biofilms." Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:17463954.

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Bacterial biofilm formation, the construction of dense, protective, multicellular communities, is a widely conserved behavior. In some bacteria, such as the Gram-positive model organism Bacillus subtilis, the genetics controlling biofilm formation are well understood. In other bacteria, however, including the Gram-negative opportunistic pathogen Pseudomonas aeruginosa, the identities or roles of many biofilm genes remain unknown. Importantly, many proposed applications of biofilm research, particularly in the medical field, require knowledge not only of biofilm assembly but also of biofilm disassembly, the latter being a recent and underdeveloped area of study. It was previously reported that B. subtilis biofilms disassemble late in their life cycle due to the incorporation of four D-amino acids (D-leucine, D-methionine, D-tryptophan, and D-tyrosine, or D-LMWY) into peptidoglycan. It was further argued that D-LMWY specifically inhibits and disassembles the biofilms of diverse bacterial species, including B. subtilis and P. aeruginosa. Here I present a contrasting report. I describe how what had been perceived as D-LMWY-mediated biofilm inhibition is actually D-tyrosine-mediated toxicity. B. subtilis is sensitive to growth inhibition by D-tyrosine due to the absence of D-tyrosyl tRNATyr deacylase (Dtd), an enzyme that prevents the misincorporation of D-tyrosine and other D-amino acids into nascent proteins. By repairing the gene for Dtd, I was able to render B. subtilis resistant to both growth inhibition and biofilm inhibition by D-tyrosine and D-LMWY. In parallel, I recovered spontaneous mutants of B. subtilis that survive in the presence of D-LMWY. These isolates harbored mutations in pathways that regulate tRNATyr charging. Three of these mutations enhanced the expression of the gene (tyrS) for tyrosyl-tRNATyr synthetase (TyrRS), while a separate mutation improved the stereoselectivity of TyrRS. I concluded that these spontaneous D-LMWY resistance mutations were compensating for the absence of Dtd. In addition to my research on B. subtilis biofilm regulation, I demonstrated a new, non-destructive screening approach for identifying P. aeruginosa biofilm genes. Using this screen, I was able to recover a wide range of known biofilm genes as well as the new biofilm gene candidates ptsP, PA14_16550, and PA14_69700. These three genes are the focus of an ongoing study dedicated to characterizing P. aeruginosa biofilm formation, particularly as it relates to the secondary messenger cyclic di-GMP. In summary, this dissertation covers aspects of biofilm formation and dispersal in two bacterial species. My work offers mechanistic insight into D-amino acid resistance, resolves the relationship between D-amino acids and biofilms, and establishes a new tool for understanding the complexities of biofilm genetics and regulation.
Biology, Molecular and Cellular

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Martins, Thaísa Zanetoni. "Mutagênese sítio-dirigida da ORF XAC0024 de Xanthomonas citri subsp. citri e suas implicações no desenvolvimento do cancro cítrico /." Jaboticabal, 2016. http://hdl.handle.net/11449/138238.

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Orientador: Jesus Aparecido Ferro
Coorientador: Helen Alves Penha
Banca: Fabrício José Jaciani
Banca: Flávia Maria de Souza Carvalho
Resumo: O cancro cítrico tem como agente causal a bactéria Xanthomonas citri subsp. citri (Xac), que afeta diferentes espécies de citros economicamente importantes. É uma doença ainda sem método curativo, e pela sua relevância e dano econômico, faz-se necessário o entendimento em termos moleculares da interação Xac-citros para o desenvolvimento de estratégias que controlem a doença. O objetivo do presente trabalho foi investigar os efeitos da deleção da ORF XAC0024 presente no genoma da Xac isolado 306, que codifica uma proteína hipotética conservada e que apresenta vários domínios putativos, entre eles o domínio peptidase M23. A hipótese é que esta proteína pode estar envolvida com a patogenicidade e/ou virulência da bactéria. Para obter o mutante ΔXAC0024 foi utilizada a técnica de mutagênese sítio-dirigida, seguida de recombinação homóloga com o vetor suicida pOK1. O mutante ΔXAC0024 foi analisado em relação às características de patogenicidade, crescimento in vivo e in vitro, capacidade de autoagregação, produção de biofilme e produção de goma xantana. O teste de patogenicidade e a curva de crescimento in vivo foram realizados em limão cravo utilizando o método de infiltração por seringa para a inoculação da bactéria. Os sintomas do desenvolvimento da doença foram registrados por fotografia digital até o 25º dia após a inoculação (dai) e a curva de crescimento in vivo também foi determinada até o 25º dai. A curva de crescimento in vitro e a agregação célula-a-célula foram analisa... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The bacteria Xanthomonas citri subsp. citri (Xac) is the causal agent of citrus canker, a disease that affects different species of economically important citrus. There is no a curative method for this disease, and do to its relevance and economic damage, it is necessary to understand at molecular level the Xac-citrus interaction in order to develop strategies to control the disease. The objective of this study was to investigate the effects of the deletion of the ORF XAC0024 present in the genome of Xac strain 306, which encodes a conserved hypothetical protein and has several putative domains, including peptidase M23 domain. It is hypothesized that this protein may be involved in the pathogenicity and / or virulence of the bacterium. For the ΔXAC0024 mutant was used for site-directed mutagenesis technique, followed by homologous recombination with the suicide vector pOK1. The ΔXAC0024 mutant was analyzed in relation to pathogenicity characteristics, growth in vivo and in vitro, self-aggregation capacity, biofilm production and production of xanthan gum. The pathogenicity test and in vivo growth curves were performed on Rangpur lime using syringe-infiltration method for the inoculation of bacteria. Symptoms of the disease development were recorded by digital photography to the 25° day after inoculation (dai) and in vivo growth curve was also determined to give the 25°. The growth curve in vitro and cell-to-cell aggregation were analyzed in liquid culture medium NB. Biofilm p... (Complete abstract click electronic access below)
Mestre

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Ghalsasi, Vihang Vivek [Verfasser], and Victor [Akademischer Betreuer] Sourjik. "Engineering bacteria to disperse bacterial biofilms / Vihang Vivek Ghalsasi ; Betreuer: Victor Sourjik." Heidelberg : Universitätsbibliothek Heidelberg, 2015. http://d-nb.info/1180608275/34.

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Ghalsasi, Vihang Vivek Verfasser], and Victor [Akademischer Betreuer] [Sourjik. "Engineering bacteria to disperse bacterial biofilms / Vihang Vivek Ghalsasi ; Betreuer: Victor Sourjik." Heidelberg : Universitätsbibliothek Heidelberg, 2015. http://d-nb.info/1180608275/34.

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Andersson, Sofia. "Characterization of Bacterial Biofilms for Wastewater Treatment." Doctoral thesis, KTH, Miljömikrobiologi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10118.

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Research performed at the Division of Environmental Microbiology has over the last years resulted in the isolation of possible bacterial key-organisms with efficient nutrient removal properties (Comamonas denitrificans, Brachymonas denitrificans, Aeromonas hydrophila). Effective use of these organisms for enhanced nutrient removal in wastewater treatment applications requires the strains to be retained, to proliferate and to maintain biological activity within theprocess. This can be achieved by immobilization of the organisms using an appropriate system.Two putative immobilization systems, agar entrapment and biofilm formation, wereassessed. Surface attached biofilm growth provided better results with respect to cell retention,proliferation and microbial activity than immobilization in agar beads. Thus, biofilm physiology was further characterized using simplified systems of single, dual or multi strain bacterial consortia containing the key-organisms as well as other wastewater treatment isolates. Mechanisms for initial adherence, biofilm formation over time, dynamics and characteristics of extracellular polymeric substances (EPS) and exopolysaccharides, nutrient removal activity as well as the effect of bacterial interactions were investigated. The results showed that all theassessed bacterial strains could form single strain biofilm providing that a suitable nutrientsupply was given. Production of EPS was found to be critical for biofilm development and both EPS and polysaccharide residue composition varied with bacterial strain, culture conditions and biofilm age. Denitrification and phosphorus removal activity of the keyorganisms was maintained in biofilm growth. Co-culturing of two or more strains resulted in both synergistic and antagonistic effects on biofilm formation as well as the microbial activitywithin the biofilm. Bacterial interactions also induced the synthesis of new polysaccharideswhich were not produced in pure strain biofilms.The complexity of single and mixed strain biofilm development and the implications of interactions on biofilm performance were underlined in this study. The data presented can be useful for modeling of biofilm systems, serve as a tool for selection of bacterial strain combinations to use for bioaugmentation/bioremediation or provide a base for further experiment design.
QC 20100622

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Taylor, Richard James. "Efficacy of industrial biocides against bacterial biofilms." Thesis, University of Birmingham, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289755.

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Roberts, Sara Kate. "Formation and control of bacterial-fungal biofilms." Thesis, University of Exeter, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324721.

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Irsfeld, Meredith Lynn. "Physical and Chemical Treatments for Bacterial Biofilms." Thesis, North Dakota State University, 2014. https://hdl.handle.net/10365/27595.

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Physical and chemical treatments have been investigated for the treatment to remove biofilms. This thesis examines the problem of the removal and prevention of biofilms by: (i) using a water jet to determine biofilm stability and (ii) testing the effect of ?-phenylethylamine (PEA) on growth and biofilm amounts. Three dimensional structures of biofilms vary in different genetic backgrounds of E. coli, we wanted to see whether changes in structures were paralleled by differences in stability of the biofilm. The water jet apparatus was used to test biofilm stability of E. coli mutants. Alteration of the cell surface structures was detrimental to biofilm stability, while alterations in metabolism had less effect on stability. PEA (0 to 50 mg/mL) was applied to bacterial strains to see the effects on growth and biofilm amounts. PEA had an inhibitory effect on growth and biofilm amounts of some bacterial strains tested.

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Livres sur le sujet "Bacterial biofilms"

Romeo, Tony, ed. Bacterial Biofilms. Springer Berlin Heidelberg, 2008. http://dx.doi.org/10.1007/978-3-540-75418-3.

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Bacterial biofilms. Springer, 2008.

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Blenkinsopp, S. A. Understanding bacterial biofilms. Elsevier, 1991.

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W, Costerton J., ed. Bacterial biofilms in nature and disease. Annual Reviews Inc., 1987.

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1933-, Quesnel Louis B., Gilbert P, and Handley Pauline S, eds. Microbial cell envelopes: Interactions and biofilms. Blackwell Scientific Publications, 1993.

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Taylor, Richard James. Efficacy of industrial biocides against bacterial biofilms. University of Birmingham, 1995.

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P, Denyer S., Gorman S. P, and Sussman Max, eds. Microbial biofilms: Formation and control. Blackwell Scientific Publications, 1993.

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Steele, Andrew. The biodecontamination of stainless steel by bacterial biofilms. University of Portsmouth, Division of Chemistry, Physics and Radiography, Microbiology Group, 1996.

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Hill, Katie Jane. Targeting of reactive vesicle systems to bacterial biofilms. University of Manchester, 1994.

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Biofilms and veterinary medicine. Springer, 2011.

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Chapitres de livres sur le sujet "Bacterial biofilms"

Maresso, Anthony William. "Biofilms." In Bacterial Virulence. Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-20464-8_12.

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Vlamakis, Hera, and Roberto Kolter. "Biofilms." In Bacterial Stress Responses. ASM Press, 2014. http://dx.doi.org/10.1128/9781555816841.ch21.

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Chopp, David L. "Simulating Bacterial Biofilms." In Deformable Models. Springer New York, 2007. http://dx.doi.org/10.1007/978-0-387-68413-0_1.

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Spratt, David. "Dental Plaque and Bacterial Colonization." In Medical Biofilms. John Wiley & Sons, Ltd, 2005. http://dx.doi.org/10.1002/0470867841.ch8.

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Fletcher, Madilyn. "Bacterial Metabolism in Biofilms." In Biofilms — Science and Technology. Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-011-1824-8_12.

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Mavrodi, Dmitri V., and James A. Parejko. "Phenazines and Bacterial Biofilms." In Microbial Phenazines. Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-40573-0_4.

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Serra, Diego O., and Regine Hengge. "Cellulose in Bacterial Biofilms." In Biologically-Inspired Systems. Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-12919-4_8.

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Costerton, J. William, and Philip S. Stewart. "Biofilms and Device-Related Infections." In Persistent Bacterial Infections. ASM Press, 2014. http://dx.doi.org/10.1128/9781555818104.ch22.

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Limoli, Dominique H., Christopher J. Jones, and Daniel J. Wozniak. "Bacterial Extracellular Polysaccharides in Biofilm Formation and Function." In Microbial Biofilms. ASM Press, 2015. http://dx.doi.org/10.1128/9781555817466.ch11.

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Nievas, Fiorela, Walter Giordano, and Pablo Bogino. "Succession of Bacterial Communities in Environmental Biofilm Structures." In Microbial Biofilms. CRC Press, 2022. http://dx.doi.org/10.1201/9781003184942-6.

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Actes de conférences sur le sujet "Bacterial biofilms"

Bhaduri, S., S. K. Mitra, and A. Kumar. "Understanding Biofilm Growth Dynamics Within a Stagnant Culture of Sporosarcina Pasteurii." In ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-36778.

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Biofilms are bacterial colonies that form at interfaces, where bacteria are encased in extracellular polymeric substances (EPS). Biofilms are ubiquitous in both artificial systems and our environment. Here we focus on understanding biofilm growth within a stagnant pool of confined diluted culture of the bacteria. Sporosarcina pasteurii is taken as the model bacterium for this study. The motivation behind the choice of this organism stems from the fact that S. Pasteurii has the unique ability to precipitate calcite inside the host media which has tremendous applications in reservoir and restoration engineering. As the biofilm evolves with time inside the confinement, the dynamics of transport is recorded continuously by an optical microscope and the data processed digitally to gain valuable insights into the bio-physical aspects of the system.

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Hassanpourfard, Mahtab, Amin Valiei, Thomas Thundat, Yang Liu, and Aloke Kumar. "Biofilm Streamer Formation in a Microfluidic Porous Media Mimic." In ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-38956.

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Several bacterial species possess the ability to attach to surfaces and colonize themselves in thin films called biofilms. Biofilms that grow in porous media are relevant to several industrial and environmental processes such as wastewater treatment and CO2 sequestration. We used Pseudomonas fluorescens, a gram negative aerobic biofilm forming bacteria, to investigate biofilm formation in a microfluidic porous media mimic device. The microfluidic device consists of an array of micro-posts, which were fabricated using soft-lithography. Subsequently, biofilm formation in this device was investigated as a function of time and the formation of filamentous biofilms known as streamers was observed. Furthermore, we used computational fluid mechanics simulation to better understanding of the streamer formation.

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Kostenko, Victoria, M. Mehdi Salek, Mohammad A. Boraey, Michael G. Surette, and Robert J. Martinuzzi. "Escherichea coli Biofilm Formation and Susceptibility in Response to Increased Shear Stresses." In ASME 2008 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2008. http://dx.doi.org/10.1115/sbc2008-193009.

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The development of biofilms, well organized communities of bacterial cells embedded in a self-generated extra-cellular polymeric matrix, on medical devices (vascular or urinary catheters, surgical implants) and surrounding tissue poses a great challenge for modern medicine. The biofilm environment confers onto bacterial cells resistance to antimicrobials and the host immune system that leads to persistent and recurrent device-associated infections, deterioration of patient life quality, and often replacement of the device [1].

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Salek, M., and R. J. Martinuzzi. "Numerical Simulation of Fluid Flow and Oxygen Transport in the Tube Flow Cells Containing Biofilms." In ASME/JSME 2007 5th Joint Fluids Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/fedsm2007-37063.

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The hydrodynamics in flow systems is known to induce phenotypic changes associated with bacterial biofilms, including increased tolerance to antimicrobial agents and biocides. Results obtained in flow cells commonly used in biological and medical studies on the influence of flow on biofilm behavior and antimicrobial susceptibility are sometimes contradictory. It is thus hypothesized that discrepancies in the results may be related to the flow cell geometry. In this study, the shear stress distribution and substrate concentration were numerically simulated inside long rectangular and square tubes. The fluid was Newtonian and a uniform distribution of biofilms, which consume the substrate from the medium, was assumed on the walls. The consumption of oxygen by biofilms was assumed to follow the Monod kinetics. The effects of flow velocity, flow cell geometry, and substrate diffusivity on wall shear stress and substrate concentration distributions were investigated. Based on simulation results, differences observed in the morphology and response of biofilms can be directly related to hydrodynamic changes caused by the flow cell configuration.

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Martins, Daniel P., Michael T. Barros, and Sasitharan Balasubramaniam. "Using Competing Bacterial Communication to Disassemble Biofilms." In NANOCOM'16: ACM The Third Annual International Conference on Nanoscale Computing and Communication. ACM, 2016. http://dx.doi.org/10.1145/2967446.2967463.

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Singal, Ashish. "Design of Electromagnetic Coils and Temperature Regulation Circuits for Impeding Microbial Growth on Medical Device Surfaces." In 2017 Design of Medical Devices Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/dmd2017-3303.

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Microorganisms that form biofilm on surface of medical devices represent a major health risk for patients and an economic burden for the health care system [1]. Biofilms are conglomerates of bacterial colonies characterized by the production of an exo-polysaccharide matrix making it challenging to eradicate them by using chemical or antibiotic treatments [2]. More than 70% of biofilm-related infections are resistant to at least one drug, therefore, alternative forms of treatments have been investigated. Previously we have reported compelling new data showing the synergistic effects of electromagnetic fields (EMF) and elevated temperatures on the colonization and survival of pathogenic bacteria on medical device surfaces [3]. Here we report the design and development of prototypical EMF coils and temperature regulation circuits that are simple and cost effective for impeding microbial growth on medical device surfaces.

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Schafer, Mark E., and Tessie McNeely. "Coincident Light/ultrasound therapy to treat bacterial biofilms." In 2015 IEEE International Ultrasonics Symposium (IUS). IEEE, 2015. http://dx.doi.org/10.1109/ultsym.2015.0244.

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Ghodssi, Reza, Mariana T. Meyer, and Young W. Kim. "Microsystems for sensing and characterization of bacterial biofilms." In 2013 IEEE Sensors. IEEE, 2013. http://dx.doi.org/10.1109/icsens.2013.6688300.

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Sears, Cynthia L. "Abstract IA04: The carcinogenic potential of bacterial biofilms." In Abstracts: AACR Special Conference: Colorectal Cancer: From Initiation to Outcomes; September 17-20, 2016; Tampa, FL. American Association for Cancer Research, 2017. http://dx.doi.org/10.1158/1538-7445.crc16-ia04.

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Veríssimo, Graciete Soares Libório, Ivanize Barbosa De Souza, and Paula Carvalhal Lage Von Buettner Ristow. "BIOFILME: MECANISMO DE VIRULÊNCIA BACTERIANA." In II Congresso Brasileiro de Saúde On-line. Revista Multidisciplinar em Saúde, 2021. http://dx.doi.org/10.51161/rems/1503.

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Introdução: Biofilmes são comunidades microbianas complexas associada à superfícies bióticas ou abióticas, circundada por uma matriz extracelular polimérica autoproduzida pelos microrganismos ali presente. A formação de biofilme protege os microrganismos de condições ambientais desafiadoras, tornando a antibioticoterapia e mecanismos de defesa imunológica do hospedeiro ineficazes contra bactérias associadas ao biofilme. Objetivo: Este estudo buscou analisar o papel do biofilme como mecanismo que contribui para virulência bacteriana. Material e métodos: Consistiu-se em uma revisão de literatura, a partir de uma abordagem qualitativa, na base de dados Pubmed, utilizando como termo de busca booleano ((biofilm[Title/Abstract]) AND (virulence mechanism[Title/Abstract])) AND (bacteria*[Title/Abstract]). Foram encontrados 19 artigos, compreendendo o período de 2003 a 2021. Resultados: Por muito tempo acreditava-se que as bactérias viviam isoladas no ambiente, hoje é notório que o fenótipo de biofilme ocorre de forma ubíqua e é a principal forma de vida bacteriana. A formação de biofilme por patógenos oportunistas em implantes biomédicos, é considerado sério problema de saúde pública. Implantes biomédicos colonizados por essas bactérias, são mais resistentes a antibioticoterapia, tempo de internação e gerar maior custo ao sistema. A formação de biofilmes em hospedeiros pode ocorrer também com microrganismos aderindo diretamente a órgãos. Pacientes com fibrose cística, infectados de forma crônica por Pseudomonas aeruginosa com capacidade de formação de biofilme nos pulmões do hospedeiro, são a principal causa de mortalidade em pacientes com esta doença. O desenvolvimento de biofilmes também é um fator relacionado à infecções alimentares. Listeria monocytogenes pode causar gastroenterite, listeriose, septicemia, encefalite, endocardite, meningite e abortos, principalmente quando associado a formação de biofilme. A formação de biofilmes também pode contribuir para a transmissão de genes de resistência a antibióticos em sistemas de distribuição de água potável. Estudos detectaram um aumento da presença de bactérias resistentes à antibióticos em tubulações industriais com presença de biofilmes. Conclusão: Biofilmes compreendem o principal estilo de vida bacteriano. A melhor compreensão do estabelecimento desse fenótipo como um mecanismo de virulência e a sua relevância biológica são essenciais para criar soluções para problemas causados por biofilmes, bem como para aplicar a biossíntese de biofilmes sem situações benéficas.

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Rapports d'organisations sur le sujet "Bacterial biofilms"

Wurl, Oliver. Biofilm-like habitat at the sea-surface: A mesocosm study, Cruise No. POS537, 14.09.2019 – 04.10.2019, Malaga (Spain) – Cartagena (Spain) - BIOFILM. University of Oldenburg, 2020. http://dx.doi.org/10.3289/cr_pos537.

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OceanRep OceanRep Startseite Kontakt Schnellsuche Einfache Suche Erweiterte Suche Blättern Autor Forschungsbereich Publikationsart Jahr Studiengang Neuzugänge Artikel – begutachtet Alle Über uns GEOMAR Bibliothek Open Access Policies Grundsätze Hilfe FAQs Statistik Impressum Biofilm-like habitat at the sea-surface: A mesocosm study, Cruise No. POS537, 14.09.2019 – 04.10.2019, Malaga (Spain) – Cartagena (Spain) - BIOFILM . Logged in as Heidi Düpow Einträge verwaltenManage recordsManage shelvesProfilGespeicherte SuchenBegutachtungAdminLogout - Tools Wurl, Oliver, Mustaffa, Nur Ili Hamizah, Robinson, Tiera-Brandy, Hoppe, Jennifer, Jaeger, Leonie, Striebel, Maren, Heinrichs, Anna-Lena, Hennings, Laura Margarethe, Goncalves, Rodrigo, Ruiz Gazulla, Carlota und Ferrera, Isabel (2020) Biofilm-like habitat at the sea-surface: A mesocosm study, Cruise No. POS537, 14.09.2019 – 04.10.2019, Malaga (Spain) – Cartagena (Spain) - BIOFILM . Open Access . POSEIDON Berichte . University of Oldenburg, Oldenburg, 35 pp. [img] Text Cruise_Reports_POS537_final.pdf - publizierte Version Available under License Creative Commons: Attribution 4.0. Download (2417Kb) | Vorschau Abstract Biofilm-like properties can form on sea surfaces, but an understanding of the underlying processes leading to the development of these biofilms is not available. We used approaches to study the development of biofilm-like properties at the sea surface, i.e. the number, abundance and diversity of bacterial communities and phytoplankton, the accumulation of gel-like particles and dissolved tracers. During the expedition POS537 we used newly developed and free drifting mesocosms and performed incubation experiments. With these approaches we aim to investigate the role of light and UV radiation as well as the microbes themselves, which lead to the formation of biofilms. With unique microbial interactions and photochemical reactions, sea surface biofilms could be biochemical reactors with significant implications for ocean and climate research, e.g. with respect to the marine carbon cycle, diversity of organisms and oceanatmosphere interactions.

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Ringelberg, David B., Karen L. Foley, and Charles M. Reynolds. Community Composition of Bacterial Biofilms Formed on Simple Soil Based Bioelectrochemical Cell Anodes and Cathodes. Defense Technical Information Center, 2012. http://dx.doi.org/10.21236/ada559329.

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Arnett, Clint, and Justin Lange. Method for localizing and differentiating bacteria within biofilms grown on indium tin oxide : spatial distribution of exoelectrogenic bacteria within intact ITO biofilms via FISH. Construction Engineering Research Laboratory (U.S.), 2017. http://dx.doi.org/10.21079/11681/25701.

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Harwood, Caroline S. Biofilm Formation by a Metabolically Versatile Bacterium. Defense Technical Information Center, 2009. http://dx.doi.org/10.21236/ada499781.

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Stanley-Wall, Nicola, and Joana Carneiro. Life of Bacteria over 200 degrees centigrade: Teachers' Guide. University of Dundee, 2022. http://dx.doi.org/10.20933/100001272.

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The “Life of bacteria over 200 degrees centigrade” video was created by the Public Engagement team at the University of Dundee’s School of Life Sciences, in collaboration with the Nicola-Stanley Wall Lab. This video follows a microbiologist performing an experiment in the laboratory and explains how scientists can study bacteria and biofilms. The video can be used by teachers to show their pupils how some microbial research is done in a professional laboratory environment. This guide helps teachers in this process.

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Nick, Jerry A. Targeted Prevention or Treatment of Bacterial Biofilm Infections of Severe Burns and Wounds. Defense Technical Information Center, 2010. http://dx.doi.org/10.21236/ada540955.

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REGUERA, GEMMA. From Nanowires to Biofilms: An Exploration of Novel Mechanisms of Uranium Transformation Mediated by Geobacter Bacteria. Office of Scientific and Technical Information (OSTI), 2014. http://dx.doi.org/10.2172/1114653.

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Choudhary, Ruplal, Victor Rodov, Punit Kohli, Elena Poverenov, John Haddock, and Moshe Shemesh. Antimicrobial functionalized nanoparticles for enhancing food safety and quality. United States Department of Agriculture, 2013. http://dx.doi.org/10.32747/2013.7598156.bard.

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Original objectives The general goal of the project was to utilize the bactericidal potential of curcumin- functionalizednanostructures (CFN) for reinforcement of food safety by developing active antimicrobial food-contact surfaces. In order to reach the goal, the following secondary tasks were pursued: (a) further enhancement of the CFN activity based on understanding their mode of action; (b) preparing efficient antimicrobial surfaces, investigating and optimizing their performance; (c) testing the efficacy of the antimicrobial surfaces in real food trials. Background to the topic The project dealt with reducing microbial food spoilage and safety hazards. Cross-contamination through food-contact surfaces is one of the major safety concerns, aggravated by bacterial biofilm formation. The project implemented nanotech methods to develop novel antimicrobial food-contact materials based on natural compounds. Food-grade phenylpropanoidcurcumin was chosen as the most promising active principle for this research. Major conclusions, solutions, achievements In agreement with the original plan, the following research tasks were performed. Optimization of particles structure and composition. Three types of curcumin-functionalizednanostructures were developed and tested: liposome-type polydiacetylenenanovesicles, surface- stabilized nanoparticles and methyl-β-cyclodextrin inclusion complexes (MBCD). The three types had similar minimal inhibitory concentration but different mode of action. Nanovesicles and inclusion complexes were bactericidal while the nanoparticlesbacteriostatic. The difference might be due to different paths of curcumin penetration into bacterial cell. Enhancing the antimicrobial efficacy of CFN by photosensitization. Light exposure strengthened the bactericidal efficacy of curcumin-MBCD inclusion complexes approximately three-fold and enhanced the bacterial death on curcumin-coated plastic surfaces. Investigating the mode of action of CFN. Toxicoproteomic study revealed oxidative stress in curcumin-treated cells of E. coli. In the dark, this effect was alleviated by cellular adaptive responses. Under light, the enhanced ROS burst overrode the cellular adaptive mechanisms, disrupted the iron metabolism and synthesis of Fe-S clusters, eventually leading to cell death. Developing industrially-feasible methods of binding CFN to food-contact surfaces. CFN binding methods were developed for various substrates: covalent binding (binding nanovesicles to glass, plastic and metal), sonochemical impregnation (binding nanoparticles to plastics) and electrostatic layer-by-layer coating (binding inclusion complexes to glass and plastics). Investigating the performance of CFN-coated surfaces. Flexible and rigid plastic materials and glass coated with CFN demonstrated bactericidal activity towards Gram-negative (E. coli) and Gram-positive (Bac. cereus) bacteria. In addition, CFN-impregnated plastic material inhibited bacterial attachment and biofilm development. Testing the efficacy of CFN in food preservation trials. Efficient cold pasteurization of tender coconut water inoculated with E. coli and Listeriamonocytogeneswas performed by circulation through a column filled with CFN-coated glass beads. Combination of curcumin coating with blue light prevented bacterial cross contamination of fresh-cut melons through plastic surfaces contaminated with E. coli or Bac. licheniformis. Furthermore, coating of strawberries with CFN reduced fruit spoilage during simulated transportation extending the shelf life by 2-3 days. Implications, both scientific and agricultural BARD Report - Project4680 Page 2 of 17 Antimicrobial food-contact nanomaterials based on natural active principles will preserve food quality and ensure safety. Understanding mode of antimicrobial action of curcumin will allow enhancing its dark efficacy, e.g. by targeting the microbial cellular adaptation mechanisms.

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Rahimipour, Shai, and David Donovan. Renewable, long-term, antimicrobial surface treatments through dopamine-mediated binding of peptidoglycan hydrolases. United States Department of Agriculture, 2012. http://dx.doi.org/10.32747/2012.7597930.bard.

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There is a need for renewable antimicrobial surface treatments that are semi- permanent, can eradicate both biofilms and planktonic pathogens over long periods of time and that do not select for resistant strains. This proposal describes a dopamine binding technology that is inexpensive, bio-friendly, non-toxic, and uses straight-forward commercially available products. The antimicrobial agents are peptidoglycanhydrolase enzymes that are non-toxic and highly refractory to resistance development. The goal of this project is to create a treatment that will be applicable to a wide variety of surfaces and will convey long-lasting antimicrobial activity. Although the immediate goal is to create staphylolytic surfaces, the technology should be applicable to any pathogen and will thus contribute to no less than 3 BARD priorities: 1) increased animal production by protecting animals from invasive and emerging diseases, 2) Antimicrobial food packaging will improve food safety and security and 3) sustainable bio- energy systems will be supported by coating fermentation vats with antimicrobials that could protect ethanolic fermentations from Lactobacillus contamination that reduces ethanol yields. The dopamine-based modification of surfaces is inspired by the strong adhesion of mussel adhesion proteins to virtually all types of surfaces, including metals, polymers, and inorganic materials. Peptidoglycanhydrolases (PGHs) meet the criteria of a surface bound antimicrobial with their site of action being extracellular peptidoglycan (the structural basis of the bacterial cell wall) that when breached causes osmotic lysis. As a proof of principle, we will develop technology using peptidoglycanhydrolase enzymes that target Staphylococcus aureus, a notoriously contagious and antimicrobial-resistant pathogen. We will test for susceptibility of the coating to a variety of environmental stresses including UV light, abrasive cleaning and dessication. In order to avoid resistance development, we intend to use three unique, synergistic, simultaneous staphylococcal enzyme activities. The hydrolases are modular such that we have created fusion proteins with three lytic activities that are highly refractory to resistance development. It is essential to use multiple simultaneous activities to avoid selecting for antimicrobial resistant strains. This strategy is applicable to both Gram positive and negative pathogens. We anticipate that upon completion of this award the technology will be available for commercialization within the time required to achieve a suitable high volume production scheme for the required enzymes (~1-2 years). We expect the modified surface will remain antimicrobial for several days, and when necessary, the protocol for renewal of the surface will be easily applied in a diverse array of environments, from food processing plants to barnyards.

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Splitter, Gary A., Menachem Banai, and Jerome S. Harms. Brucella second messenger coordinates stages of infection. United States Department of Agriculture, 2011. http://dx.doi.org/10.32747/2011.7699864.bard.

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Aim 1: To determine levels of this second messenger in: a) B. melitensiscyclic-dimericguanosinemonophosphate-regulating mutants (BMEI1448, BMEI1453, and BMEI1520), and b) B. melitensis16M (wild type) and mutant infections of macrophages and immune competent mice. (US lab primary) Aim 2: To determine proteomic differences between Brucelladeletion mutants BMEI1453 (high cyclic-dimericguanosinemonophosphate, chronic persistent state) and BMEI1520 (low cyclicdimericguanosinemonophosphate, acute virulent state) compared to wild type B. melitensisto identify the role of this second messenger in establishing the two polar states of brucellosis. (US lab primary with synergistic assistance from the Israel lab Aim 3: Determine the level of Brucellacyclic-dimericguanosinemonophosphate and transcriptional expression from naturally infected placenta. (Israel lab primary with synergistic assistance from the US lab). B. Background Brucellaspecies are Gram-negative, facultative intracellular bacterial pathogens that cause brucellosis, the most prevalent zoonosis worldwide. Brucellosis is characterized by increased abortion, weak offspring, and decreased milk production in animals. Humans are infected with Brucellaby consuming contaminated milk products or via inhalation of aerosolized bacteria from occupational hazards. Chronic human infections can result in complications such as liver damage, orchitis, endocarditis, and arthritis. Brucellaspp. have the ability to infect both professional and non-professional phagocytes. Because of this, Brucellaencounter varied environments both throughout the body and within a cell and must adapt accordingly. To date, few virulence factors have been identified in B. melitensisand even less is known about how these virulence factors are regulated. Subsequently, little is known about how Brucellaadapt to its rapidly changing environments, and how it alternates between acute and chronic virulence. Our studies suggest that decreased concentrations of cyclic dimericguanosinemonophosphate (c-di-GMP) lead to an acute virulent state and increased concentrations of c-di-GMP lead to persistent, chronic state of B. melitensisin a mouse model of infection. We hypothesize that B. melitensisuses c-di-GMP to transition from the chronic state of an infected host to the acute, virulent stage of infection in the placenta where the bacteria prepare to infect a new host. Studies on environmental pathogens such as Vibrio choleraeand Pseudomonas aeruginosasupport a mechanism where changes in c-di-GMP levels cause the bacterium to alternate between virulent and chronic states. Little work exists on understanding the role of c-di-GMP in dangerous intracellular pathogens, like Brucellathat is a frequent pathogen in Israeli domestic animals and U.S. elk and bison. Brucellamust carefully regulate virulence factors during infection of a host to ensure proper expression at appropriate times in response to host cues. Recently, the novel secondary signaling molecule c-di-GMP has been identified as a major component of bacterial regulation and we have identified c-di-GMP as an important signaling factor in B. melitensishost adaptation. C. Major conclusions, solutions, achievements 1. The B. melitensis1453 deletion mutant has increased c-di-GMP, while the 1520 deletion mutant has decreased c-di-GMP. 2. Both mutants grow similarly in in vitro cultures; however, the 1453 mutant has a microcolony phenotype both in vitro and in vivo 3. The 1453 mutant has increased crystal violet staining suggesting biofilm formation. 4. Scanning electron microscopy revealed an abnormal coccus appearance with in increased cell area. 5. Proteomic analysis revealed the 1453 mutant possessed increased production of proteins involved in cell wall processes, cell division, and the Type IV secretion system, and a decrease in proteins involved in amino acid transport/metabolism, carbohydrate metabolism, fatty acid production, and iron acquisition suggesting less preparedness for intracellular survival. 6. RNAseq analysis of bone marrow derived macrophages infected with the mutants revealed the host immune response is greatly reduced with the 1453 mutant infection. These findings support that microlocalization of proteins involved in c-di-GMP homeostasis serve a second messenger to B. melitensisregulating functions of the bacteria during infection of the host.

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