Project description:transcriptome analysis of enterohemorrhagic E. coli treated with either one of two different concentrations of short chain fatty acid mixes or the corresponding sodium chloride osmolarity control
Project description:transcriptome analysis of enterohemorrhagic E. coli treated with either one of two different concentrations of short chain fatty acid mixes or the corresponding sodium chloride osmolarity control four conditions: 30mM SCFA mix; 30mM NaCl control; 172mM SCFA mix: 172 mM NaCl control. Biological replicates: 4 per group
Project description:An experiment to identify the downstream targets of PatE, a prophage encoded AraC-like transcriptional regulator, in transcriptional activation of acid-resistance pathways of enterohemorrhagic Escherichia coli strain EDL933 using deletion and complementation strains (Delta3 and Delta3_1, respectively).
Project description:In 2011, in Germany, Escherichia coli O104:H4 caused the enterohemorrhagic E. coli (EHEC) outbreak with the highest incidence rate of hemolytic uremic syndrome. This pathogen carries an exceptionally potent combination of EHEC- and enteroaggregative E. coli (EAEC)-specific virulence factors. Here, we identified an E. coli O104:H4 isolate that carried a single nucleotide polymorphism (SNP) in the start codon (ATG>ATA) of rpoS, encoding the alternative sigma factor S. The rpoS ATG>ATA SNP was associated with enhanced EAEC-specific virulence gene expression. Deletion of rpoS in E. coli O104:H4 Dstx2 and typical EAEC resulted in a similar effect. Both rpoS ATG>ATA and DrpoS strains exhibited stronger virulence-related phenotypes in comparison to wild type. Using promoter-reporter gene fusions, we demonstrated that wild-type RpoS repressed aggR, encoding the main regulator of EAEC virulence. In summary, our work demonstrates that RpoS acts as a global repressor of E. coli O104:H4 virulence, primarily through an AggR-dependent mechanism.
Project description:Biosynthesis of carboxylic acids and fatty acids from renewable biomass is a key issue in biorefinery. However, their productivities are often limited due to various toxic effects of the products on the host organisms. Here, we have investigated the factors that influence tolerance of Escherichia coli to long chain carboxylic acid (e.g., n-heptanoic acid)-induced stress by using transcriptome analysis. The metabolic and genomic responses of E. coli BL21 and MG1655 strains with n-heptanoic acid indicated that acid stress is one of the major stresses, which might be generated by n-heptanoic acid in addition to the presumed solvent-like stress.
Project description:Investigation of whole genome gene expression level changes in a E. coli fatty acid overproducing strain with or without heterologous expression of the M. luteus FabH. The strain expressing M. luteus FabH produces more methyl ketones. This study will be further described in Goh, E.B., E.E.K. Baidoo, J.D. Keasling, and H.R. Beller. Engineering of bacterial methyl ketone synthesis for biofuels. A 11 microarray study using total RNA recovered from six separate control cultures of Escherichia coli K-12 DH1 fatty acid overproducing strain with empty vector and five separate cultures of test strain, Escherichia coli K-12 DH1 fatty acid overproducing strain with vector overexpressing M. luteus FabH. Each chip measures the expression level of 4,254 genes from Escherichia coli K-12 with eight 60-mer probe pairs (PM/MM) per gene, with 2-fold technical redundancy.
Project description:Persisters represent a small bacterial population that is dormant and that survives under antibiotic treatment without experiencing genetic adaptation. Persisters are also considered one of the major reasons for recalcitrant chronic bacterial infections. Although several mechanisms of persister formation have been proposed, it is not clear how cells enter the dormant state in the presence of antibiotics or how persister cell formation can be effectively controlled. A fatty acid compound, cis-2-decenoic acid, was reported to decrease persister formation as well as revert the dormant cells to a metabolically active state. We reasoned that some fatty acid compounds may be effective in controlling bacterial persistence because they are known to benefit host immune systems. This study investigated persister cell formation by pathogens that were exposed to nine fatty acid compounds during antibiotic treatment. We found that three medium chain unsaturated fatty acid ethyl esters (ethyl trans-2-decenoate, ethyl trans-2-octenoate, and ethyl cis-4-decenoate) decreased the level of Escherichia coli persister formation up to 110-fold when cells were exposed to ciprofloxacin or ampicillin antibiotics. RNA sequencing analysis and gene deletion persister studies elucidated that these fatty acids inhibit bacterial persistence by regulating antitoxin HipB. A similar persister cell reduction was observed for pathogenic E. coli EDL933, Pseudomonas aeruginosa PAO1, and Serratia marcescens ICU2-4 strains. This study demonstrates that fatty acid ethyl esters can be used to disrupt bacterial dormancy to combat persistent infectious diseases.
Project description:Short chain fatty acids were shown to affect regulatory immune response in context of autoimmune diseases like multiple sclerosis (MS). Recent studys in an animal model of MS revealed significant impact of short chain fatty acid propionate (PA) on the differentiation towards regulatory Tcells (Treg). In a translational proof of concept study PA was administered to relapse remitting MS patients. We observed an increase of Treg in peripheral blood as well as functional improvement in Treg suppressive capacity beside a decrease of proinflammatory Thelper1 and 17 cells. To investigate underlying mechanisms of the observed shift in immune cell balance, intensive transcriptomic analysis on isolated Treg from whole blood PBMC of PA treated relapse remitting MS patients was performed at baseline, 14 days and 90 days of treatment.
Project description:An experiment to identify the downstream targets of PatE, a prophage encoded AraC-like transcriptional regulator, in transcriptional activation of acid-resistance pathways of enterohemorrhagic Escherichia coli strain EDL933 using deletion and complementation strains (Delta3 and Delta3_1, respectively). Incomplete 2 factor with dye swaps. Genotype: 3 levels (wt, detla3, delta3_1) Bicarbonate: 2 levels (pos, neg) on wt only. 4 biological replicates, 2 in each dye orientation. Microarrays processed at Australian Genome Research Facility.
