Genome wide transcriptome analysis of bacillus cereus producing biofilm in food environment.

: Background B. cereus is a human pathogen most commonly associated with food poisoning that causes two types of food-borne infections: the emetic disease caused by a thermostable toxin production in food and the diarrhoeal syndrome which is the result of ingested B. cereus spores that germinate in the human intestine. The B. cereus mechanism of intoxication and infection is strongly influenced by its spore-producing and germinating cycle in food together with the capacity to form biofilm. Objectives 1) Analysis of the biofilm formation capacity in food model. 2) Use a genome-wide microarray transcriptome analysis to explore transcriptional changes and molecular mechanism, behind the process of spore germination, outgrowth and toxin production. 3) Determination of the mRNA transcripts abundance and their role in dormant spores. Methods B. cereus UC10070 isolated from a food biofilm has been used. SEM and SEM-X-ray microanalysis (Bassi et al. 2009) were set to monitor the B. cereus biological cycle in food model. Combimatrix microarray 12K were applied to all samples and conditions analysed. The capacity of this strain to form biofilm has been assessed in flow cells. Conclusions B. cereus UC10070 was able to form biofilm on different abiotic materials and food matrices. Transcriptome and analysis of orthologous groups obtained, provide new basic knowledge on Bacillus cereus for what concerns genes responsible of germination and late-log/stationary phase. Pattern of major virulence genes involved in B. cereus-associated food borne disease have also been investigated.