Transcriptome analysis of Bacillus thuringiensis spore life, germination and cell outgrowth in a vegetable-based food model

Toxigenic species belonging to Bacillus cereus sensu lato, including Bacillus thuringiensis, cause foodborne\r\noutbreaks thanks to their capacity to survive as spores and to grow in food matrixes. The goal of this\r\nwork was to assess by means of a genome-wide transcriptional assay, in the food isolate B. thuringiensis\r\nUC10070, the gene expression behind the process of spore germination and consequent outgrowth in a\r\nvegetable-based food model. Scanning electron microscopy and Energy Dispersive X-ray microanalysis\r\nwere applied to select the key steps of B. thuringiensis UC10070 cell cycle to be analyzed with DNAmicroarrays.\r\nAt only 40 min from heat activation, germination started rapidly and in less than two\r\nhours spores transformed in active growing cells. A total of 1646 genes were found to be differentially\r\nexpressed and modulated during the entire B. cereus life cycle in the food model, with most of the\r\nsignificant genes belonging to transport, transcriptional regulation and protein synthesis, cell wall and\r\nmotility and DNA repair groups. Gene expression studies revealed that toxin-coding genes nheC, cytK and\r\nhblC were found to be expressed in vegetative cells growing in the food model.