Project description:Competitive hybridization of V1 variant of genome sequenced C. jejuni strain 11168 versus V1 variant in which flhA gene has been disrupted. Keywords: repeat sample
Project description:Competive hybridization of V1 variant of genome sequenced C. jejuni strain 11168 versus V1 variant in which fliA gene encoding sigma 28 has been disrupted Keywords: repeat sample
Project description:Campylobacter jejuni helical shape is important for colonization and host interactions with straight mutants having altered biological properties. Passage on calcofluor white (CFW) resulted in C. jejuni 81-176 isolates with morphology changes: either a straight morphology from frameshift mutations and single nucleotide polymorphisms in peptidoglycan hydrolase genes pgp1 or pgp2 or a reduction in curvature due a frameshift mutation in cjj81176_1105, a putative peptidoglycan endopeptidase. Shape defects were restored by complementation. Whole genome sequencing of CFW-passaged strains showed no specific changes correlating to CFW exposure. The cjj81176_1279 (recR; recombinational DNA repair) and cjj81176_1449 (unknown function) genes were highly variable in all 81-176 strains sequenced. A frameshift mutation in pgp1 of our laboratory isolate of the straight genome sequenced variant of 11168 (11168-GS) was also identified. The PG muropeptide profile of 11168-GS was identical to that of ?pgp1 in the original minimally passaged 11168 strain (11168-O). Introduction of wild type pgp1 into 11168-GS did not restore helical morphology. The recR gene was also highly variable in 11168 strains. Microbial cell-to-cell heterogeneity is proposed as a mechanism of ensuring bacterial survival in sub-optimal conditions. In certain environments, changes in C. jejuni morphology due to genetic heterogeneity may promote C. jejuni survival.
Project description:INTRODUCTION:Campylobacter jejuni is the leading cause of foodborne bacterial enteritis in humans, and yet little is known in regard to how genetic diversity and metabolic capabilities among isolates affect their metabolic phenotype and pathogenicity. OBJECTIVES:For instance, the C. jejuni 11168 strain can utilize both L-fucose and L-glutamate as a carbon source, which provides the strain with a competitive advantage in some environments and in this study we set out to assess the metabolic response of C. jejuni 11168 to the presence of L-fucose and L-glutamate in the growth medium. METHODS:To achieve this, untargeted hydrophilic liquid chromatography coupled to mass spectrometry was used to obtain metabolite profiles of supernatant extracts obtained at three different time points up to 24 h. RESULTS:This study identified both the depletion and the production and subsequent release of a multitude of expected and unexpected metabolites during the growth of C. jejuni 11168 under three different conditions. A large set of standards allowed identification of a number of metabolites. Further mass spectrometry fragmentation analysis allowed the additional annotation of substrate-specific metabolites. The results show that C. jejuni 11168 upon L-fucose addition indeed produces degradation products of the fucose pathway. Furthermore, methionine was faster depleted from the medium, consistent with previously-observed methionine auxotrophy. CONCLUSIONS:Moreover, a multitude of not previously annotated metabolites in C. jejuni were found to be increased specifically upon L-fucose addition. These metabolites may well play a role in the pathogenicity of this C. jejuni strain.
Project description:Transcriptional analysis (RNA hybridization) for 11168-G (genome sequenced) vs. 11168-O (original), cultured microaerobically or anaerobically (published as "severely O2-limited). Published in Gaynor et al, J. Bacteriology 186:503-517 The genome sequence of the enteric bacterial pathogen Campylobacter jejuni NCTC 11168 (11168-GS) was published in 2000, providing a valuable resource for the identification of C. jejuni-specific colonization and virulence factors. Surprisingly, the 11168-GS clone was subsequently found to colonize 1-day-old chicks following oral challenge very poorly compared to other strains. In contrast, we have found that the original clinical isolate from which 11168-GS was derived, 11168-O, is an excellent colonizer of chicks. Other marked phenotypic differences were also identified: 11168-O invaded and translocated through tissue culture cells far more efficiently and rapidly than 11168-GS, was significantly more motile, and displayed a different morphology. Serotyping, multiple high-resolution molecular genotyping procedures, and subtractive hybridization did not yield observable genetic differences between the variants, suggesting that they are clonal. However, microarray transcriptional profiling of these strains under microaerobic and severely oxygen-limited conditions revealed dramatic expression differences for several gene families. Many of the differences were in respiration and metabolism genes and operons, suggesting that adaptation to different oxygen tensions may influence colonization potential. This correlates biologically with our observation that anaerobically priming 11168-GS or aerobically passaging 11168-O caused an increase or decrease, respectively, in colonization compared to the parent strain. Expression differences were also observed for several flagellar genes and other less well-characterized genes that may participate in motility. Targeted sequencing of the sigma factors revealed specific DNA differences undetected by the other genomic methods An all pairs experiment design type is where all labeled extracts are compared to every other labeled extract. Keywords: all_pairs Overall design: Computed
Project description:Gene content comparison of control C. jejuni subsp. jejuni strain 11168 which colonizes and causes disease in C57BL/6 IL-10-/- mice versus C. jejuni strains D6844, D6845, D6846, D6847, D6848, D6849, D0121, D0835, D2586, D2600,33560 and NW in the C57BL/6 IL-10-/- mice. Keywords: DNA/DNA comparison Overall design: Two genome comparison of disease strain versus non disease strain of C.j., 4 Biological replicates - 2 of which were dye swaps
Project description:This study describes a novel approach to identify unique genomic DNA sequences from the unsequenced strain C. jejuni ATCC 43431 by comparison with the sequenced strain C. jejuni NCTC 11168. A shotgun DNA microarray was constructed by arraying 9,600 individual DNA fragments from a C. jejuni ATCC 43431 genomic library onto a glass slide. DNA fragments unique to C. jejuni ATCC 43431 were identified by competitive hybridization to the array with genomic DNA of C. jejuni NCTC 11168. The plasmids containing unique DNA fragments were sequenced, allowing the identification of up to 130 complete and incomplete genes. Potential biological roles were assigned to 66% of the unique open reading frames. The mean G+C content of these unique genes (26%) differs significantly from the G+C content of the entire C. jejuni genome (30.6%). This suggests that they may have been acquired through horizontal gene transfer from an organism with a G+C content lower than that of C. jejuni. Because the two C. jejuni strains differ by Penner serotype, a large proportion of the unique ATCC 43431 genes encode proteins involved in lipooligosaccharide and capsular biosynthesis, as expected. Several unique open reading frames encode enzymes which may contribute to genetic variability, i.e., restriction-modification systems and integrases. Interestingly, many of the unique C. jejuni ATCC 43431 genes show identity with a possible pathogenicity island from Helicobacter hepaticus and components of a potential type IV secretion system. In conclusion, this study provides a valuable resource to further investigate Campylobacter diversity and pathogenesis.
Project description:The fastidious nature of the foodborne bacterial pathogen Campylobacter jejuni contrasts with its ability to survive in the food chain. The formation of biofilms, or the integration into existing biofilms by C. jejuni, is thought to contribute to food chain survival. As extracellular DNA (eDNA) has previously been proposed to play a role in C. jejuni biofilms, we have investigated the role of extracellular DNases (eDNases) produced by C. jejuni in biofilm formation. A search of 2791 C. jejuni genomes highlighted that almost half of C. jejuni genomes contains at least one eDNase gene, but only a minority of isolates contains two or three of these eDNase genes, such as C. jejuni strain RM1221 which contains the cje0256, cje0566 and cje1441 eDNase genes. Strain RM1221 did not form biofilms, whereas the eDNase-negative strains NCTC 11168 and 81116 did. Incubation of pre-formed biofilms of NCTC 11168 with live C. jejuni RM1221 or with spent medium from a RM1221 culture resulted in removal of the biofilm. Inactivation of the cje1441 eDNase gene in strain RM1221 restored biofilm formation, and made the mutant unable to degrade biofilms of strain NCTC 11168. Finally, C. jejuni strain RM1221 was able to degrade genomic DNA from C. jejuni NCTC 11168, 81116 and RM1221, whereas strain NCTC 11168 and the RM1221 cje1441 mutant were unable to do so. This was mirrored by an absence of eDNA in overnight cultures of C. jejuni RM1221. This suggests that the activity of eDNases in C. jejuni affects biofilm formation and is not conducive to a biofilm lifestyle. These eDNases do however have a potential role in controlling biofilm formation by C. jejuni strains in food chain relevant environments.
Project description:Transcriptional analysis (RNA hybridization) for 11168-G (genome sequenced) vs. 11168-O (original), cultured microaerobically or anaerobically (published as "severely O2-limited). Published in Gaynor et al, J. Bacteriology 186:503-517 The genome sequence of the enteric bacterial pathogen Campylobacter jejuni NCTC 11168 (11168-GS) was published in 2000, providing a valuable resource for the identification of C. jejuni-specific colonization and virulence factors. Surprisingly, the 11168-GS clone was subsequently found to colonize 1-day-old chicks following oral challenge very poorly compared to other strains. In contrast, we have found that the original clinical isolate from which 11168-GS was derived, 11168-O, is an excellent colonizer of chicks. Other marked phenotypic differences were also identified: 11168-O invaded and translocated through tissue culture cells far more efficiently and rapidly than 11168-GS, was significantly more motile, and displayed a different morphology. Serotyping, multiple high-resolution molecular genotyping procedures, and subtractive hybridization did not yield observable genetic differences between the variants, suggesting that they are clonal. However, microarray transcriptional profiling of these strains under microaerobic and severely oxygen-limited conditions revealed dramatic expression differences for several gene families. Many of the differences were in respiration and metabolism genes and operons, suggesting that adaptation to different oxygen tensions may influence colonization potential. This correlates biologically with our observation that anaerobically priming 11168-GS or aerobically passaging 11168-O caused an increase or decrease, respectively, in colonization compared to the parent strain. Expression differences were also observed for several flagellar genes and other less well-characterized genes that may participate in motility. Targeted sequencing of the sigma factors revealed specific DNA differences undetected by the other genomic methods An all pairs experiment design type is where all labeled extracts are compared to every other labeled extract. Computed
Project description:Strain specific growth of C. jejuni on fucose has been linked to a plasticity region of the chromosome (PR2) and confers a competitive advantage during intestinal colonization. Growth on fucose induces gene expression of PR2 genes, but the regulatory mechanism of the structural genes involved with fucose utilization is unknown. Additionally, the mechanism of fucose dissimilation by C. jejuni is not known since no fucose catabolism homologs are found in the C. jejuni genome. Transcriptional profiles of C. jejuni grown with and without fucose may provide insight in to the genes that are necessary for fucose utilization. The design utilized an available two color microarray slide for the entire transcriptome of Campylobacter jejuni wild type strain NCTC 11168. Each sample represents one competitive hybridization: sham-treated NCTC 11168 v.s. 25mM fucose treated NCTC 11168. There were four biological replicates of each sample with a dye swap introduced in alternating replicates. Samples were independently grown, treated and harvested.