Project description:Salmonella Typhimurium is one of the major foodborne pathogens due to its biofilm formation on food contact surfaces. A polymer of positively charged lysine, ε-Polylysine has been demonstrated to inhibit biofilm formation of both Gram-positive and -negative bacteria. To elucidate the mechanism for inhibition of biofilm formation by ε-Polylysine, transcriptional profiles were compared between the cells before and after treatment with ε-Polylysine in Salmonella Typhimurium. A genome-wide DNA microarray analysis was performed after cultivation in 0.1% bacto soytone in the presence of 0.001% ε-Polylysine at 30°C for 2 h. Genes involved in curli and cellulose production, quorum sensing, and flagellar motility were down-regulated, whereas genes associated with colanic acid synthesis were up-regulated. The data from microarray was validated by RT-qPCR. Furthermore, production of colanic acid in S. Typhimurium decreased in the presence of ε-Polylysine. The outcome of this study provides a basic understanding of the anti-biofilm mechanisms of ε-Polylysine and may contributes to develop new disinfectant to control biofilm during food manufacturing and storage.
Project description:Salmonella spp. biofilms have been implicated in persistence in the environment and plant surfaces. In addition, Salmonella is able to form biofilms on the surface on cholesterol gallstones. The ability of Salmonella spp. on these surfaces is superior to biofilm formation on surfaces on glass or plastic. Thus, we hypothesized that Salmonella gene expression is specific during biofilm development on cholesterol surfaces.
Project description:This study investigates the mechanisms employed by Salmonella to colonise and establish itself on fresh produce at critical timepoints following infection. We established an alfalfa infection model and compared the findings to those obtained from glass surfaces. Our research revealed dynamic changes in the pathways associated with biofilm formation over time, with distinct plant-specific and glass-specific mechanisms for biofilm formation, alongside the identification of shared genes playing pivotal roles in both contexts.
Project description:Salmonella spp. biofilms have been implicated in persistence in the environment and plant surfaces. In addition, Salmonella is able to form biofilms on the surface on cholesterol gallstones. The ability of Salmonella spp. on these surfaces is superior to biofilm formation on surfaces on glass or plastic. Thus, we hypothesized that Salmonella gene expression is specific during biofilm development on cholesterol surfaces. Flow through assays were performed whereby S. Typhimurium was inoculated into chambers coated with glass or cholesterol. At 24h post-inoculation, planktonic (from the flow through), biofilms (from glass or cholesterol) were collected. Thus we had 4 samples: Planktonic (2) and Biofilms (2), each with 2 biological replicates
Project description:Neisseria gonorrhoeae, the etiologic agent of gonorrhea, is frequently asymptomatic in women, often leading to chronic infections. One factor contributing to this may be biofilm formation. N. gonorrhoeae can form biofilms over glass and plastic surfaces. There is also evidence that biofilm formation may occur during natural cervical infection. To further study the mechanism of this biofilm formation, transcriptional profiles of N. gonorrhoeae biofilm were compared to planktonic profiles. Biofilm RNA was extracted from N. gonorrhoeae 1291 grown for 48 hours in continuous flow chambers over glass. Planktonic RNA was extracted from the biofilm runoff. When biofilm was compared to planktonic growth, 3.8 % of the genome was differentially regulated. Genes highly up-regulated in biofilm included aniA, norB, and ccp, which play critical roles in anaerobic metabolism and oxidative stress tolerance. Down-regulated genes included the nuo gene cluster (NADH dehydrogenase) and the cytochrome bcI complex, which are involved in aerobic respiration and are thought to contribute to endogenous oxidative stress. Furthermore, we determined that aniA, ccp, and norB insertional mutants are attenuated for biofilm formation over glass and transformed human cervical epithelial cells (THCEC). This data suggests that biofilm formation could minimize oxidative stress during cervical infection and allow N. gonorrhoeae to maintain a nitric oxide steady state that may be anti-inflammatory.
Project description:To combat dental implant-associated infections, there is a need for novel materials which effectively inhibit bacterial biofilm formation. In the present study, a titanium surface functionalization based on the “slippery liquid-infused porous surfaces” (SLIPS) principle was analyzed in an oral flow chamber system. The immobilized liquid layer was stable over 13 days of continuous flow. With increasing flow rates, the surface exhibited a significant reduction in attached biofilm of both the oral initial colonizer Streptococcus oralis and an oral multi-species biofilm composed of S. oralis, Actinomyces naeslundii, Veillonella dispar and Porphyromonas gingivalis. Using single cell force spectroscopy, reduced bacterial adhesion forces on the lubricant layer could be measured. Gene expression patterns in biofilms on SLIPS, on control surfaces and planktonic cultures were also compared. For this purpose, the genome of S. oralis strain ATCC® 9811TM was sequenced using PacBio Sequel technology. Even though biofilm cells showed clear changes in gene expression compared to planktonic cells, no differences could be detected between bacteria on SLIPS and on control surfaces. Therefore, it can be concluded that the ability of liquid-infused titanium to repel biofilms is solely due to weakened bacterial adhesion to the underlying liquid interface.
Project description:The plant pathogen Agrobacterium tumefaciens attaches to and forms biofilms on both biotic and abiotic surfaces. The transition between free-living, planktonic A. tumefaciens and multicellular biofilms is regulated by several well-defined environmental and nutritional inputs, including pH, oxygen tension, and phosphate concentration. In many bacterial species limiting iron levels inhibit attachment and biofilm formation. We demonstrate that A. tumefaciens biofilm formation is reduced under limiting iron conditions. Treatment of A. tumefaciens cultures with EDDHA, an iron-specific extracellular chelator, inhibited both planktonic growth rate and adherent biomass. These effects were reversed upon addition of exogenous ferrous iron. This reduced biofilm formation effect is independent of the known iron-responsive regulators Irr and RirA. Transcriptome analysis comparing gene expression under iron-replete versus iron-deficient conditions identified hundreds of genes that are differentially regulated. Downregulated genes suggest an iron sparing response. Four biological replicates, independent RNA preparations, one dye swap.
Project description:The plant pathogen Agrobacterium tumefaciens attaches to and forms biofilms on both biotic and abiotic surfaces. The transition between free-living, planktonic A. tumefaciens and multicellular biofilms is regulated by several well-defined environmental and nutritional inputs, including pH, oxygen tension, and phosphate concentration. In many bacterial species limiting iron levels inhibit attachment and biofilm formation. We demonstrate that A. tumefaciens biofilm formation is reduced under limiting iron conditions. Treatment of A. tumefaciens cultures with EDDHA, an iron-specific extracellular chelator, inhibited both planktonic growth rate and adherent biomass. These effects were reversed upon addition of exogenous ferrous iron. This reduced biofilm formation effect is independent of the known iron-responsive regulators Irr and RirA. Transcriptome analysis comparing gene expression under iron-replete versus iron-deficient conditions identified hundreds of genes that are differentially regulated. Downregulated genes suggest an iron sparing response.
Project description:The plant pathogen Agrobacterium tumefaciens attaches to and forms biofilms on both biotic and abiotic surfaces. The transition between free-living, planktonic A. tumefaciens and multicellular biofilms is regulated by several well-defined environmental and nutritional inputs, including pH, oxygen tension, and phosphate concentration. In many bacterial species limiting iron levels inhibit attachment and biofilm formation. In several systems intracellular levels of the redox-active manganous (Mn2+) and ferrous (Fe2+) ions are interrelated and have tight corresponding regulation with respect to one another. We show that limiting manganese concentrations elicit similar growth and biofilm phenotypes to those seen under iron-limiting conditions. Microarray analysis comparing gene expression in manganese-replete versus manganese-limiting conditions identified a small number of differentially regulated transcripts. These results indicate that the redox-active manganous and ferrous ions are required for wild-type levels of growth and biofilm formation, and that the manganese-dependent response is primarily post-transcriptional and complementary to, but not redundant with, the iron-dependent response. Four biological replicates, independent RNA preparations, two dye swaps.
Project description:Pseudomonas aeruginosa is a ubiquitous gram-negative bacterium capable of forming biofilms on living and non-living surfaces, frequently leading to undesirable consequences. We found that lauroyl arginate ethyl (LAE), a synthetic non-oxidizing biocide, inhibited biofilm formation by P. aeruginosa at sub-growth inhibitory concentrations in both static and flow conditions. To identify the genes targeted by LAE, a global transcriptome analysis was conducted using a gene chip microarray.