Project description:Bacillus weihenstephanensis is a subspecies of the Bacillus cereus sensu lato group of spore forming bacteria known to cause food spoilage or food poisoning. The key distinguishing phenotype of B. weihenstephanensis is its ability to grow below 7°C or, from a food safety perspective, to grow and potentially produce toxins in a refrigerated environment. In order to gain insight into to the mechanistic basis of its psychrotolerant phenotype, as well as elucidate relevant aspects of its toxigenic profile, the proteome profiles of cells grown at either 6°C or 30°C were compared.
Project description:Pathogenic species belonging to Bacillus cereus sensu lato group possess a high evolutionary advantage in the environment and in food matrices thanks to their capacity to survive as silent spores to harsh environmental insults and grow at relatively low temperatures. Ready to re-heat products are at severe risk for contamination by members of Bacillus cereus s.l. group if not stored at proper conditions. In this work, the goal was to assess, by means of a genome-wide transcriptional assay, the isolated strain Bacillus cereus UC10070 gene expression behind the process of spore germination and consequent outgrowth in an artificially contaminated vegetable-based food model. A vegetable food model subjected to a heat treatment was determined to present favourable conditions for spores germination. Microscopic analyses together with OD measurements were applied to select the key steps of B. cereus cell cycle to be used for the microarray analysis. Using this approach we found a total of 1,646 probe sets differentially expressed and modulated during the entire B. cereus life cycle in the vegetable foodstuff.
2015-01-26 | GSE65259 | GEO
Project description:WGS Bacillus cereus sensu lato
Project description:The glycopeptide vancomycin is a drug of choice for the treatment of severe non-gastrointestinal infections with members of Bacillus cereus sensu lato. Recently, sporadic detection of vancomycin resistant phenotypes emerged, mostly for agar diffusion testing. The food packaging isolate BC70 displayed a pseudo-resistant phenotype for vancomycin in both Etest and disk diffusion. In this work, we used RNA-Seq on the nanopore platform to study differentially expressed genes in BC70 cells, which were able to actively move into the inhibition zone during vancomycin susceptibility testing using Etest and therefore appeared to be resistant. Transcriptomic analysis revealed several key genes of biofilm formation (e.g. calY, tasA, krsEABC) to be upregulated in pseudo-resistant cells suggesting a biofilm-related mechanism of motility. Downregulation of virulence (e.g. hblABCD, nheABC, plcR) and flagellar genes compared to swarming cells also confirmed the non-swarming phenotype of the pseudo-resistant isolate. This type of biofilm-related motility was distinct from swarming motility and joined the list of bacterial strategies interfering with reliable antimicrobial susceptibility testing.
Project description:Pathogenic species belonging to Bacillus cereus sensu lato group possess a high evolutionary advantage in the environment and in food matrices thanks to their capacity to survive as silent spores to harsh environmental insults and grow at relatively low temperatures. Ready to re-heat products are at severe risk for contamination by members of Bacillus cereus s.l. group if not stored at proper conditions. In this work, the goal was to assess, by means of a genome-wide transcriptional assay, the isolated strain Bacillus cereus UC10070 gene expression behind the process of spore germination and consequent outgrowth in an artificially contaminated vegetable-based food model. A vegetable food model subjected to a heat treatment was determined to present favourable conditions for spores germination. Microscopic analyses together with OD measurements were applied to select the key steps of B. cereus cell cycle to be used for the microarray analysis. Using this approach we found a total of 1,646 probe sets differentially expressed and modulated during the entire B. cereus life cycle in the vegetable foodstuff. RNA was isolated from the dormant spores (DS), germinating spores at 40 minutes (GSP), early-log phase at 2h (C2h) and late log phase cells at 12 hours (C12h) after thermal treatment of B. cereus UC10070 previously isolated froma biofilm on a spoiled vegetable-based puree. There were 3 biological replicates (independent cultures) for each condition. Complete genome sequence of B. thuringiensis sv konkukian str. 97-27 (NCBI Reference Sequence: NC_005957.1) was chosen for its high homology with B. cereus s.l. UC10070, to design probes corresponding to 5,197 genes spotted in duplicates onto ElectraSenseH 12K microarrays chip.