Biofilm formation and sliding translocation in Bacillus cereus

The main goal of this study is to identify and characterize the genes involved in biofilm formation and to understand the mechanism of sliding in Bacillus cereus.; B. cereus is a rod-shaped, sporeforming gram-positive bacterium. It is a foodborne pathogen that causes emetic and diarrheal syndromes as well as a variety of local and systemic infections. It can form biofilms on different materials used in food processing and biofilm accumulation in food processing environments can lead to decreased food quality and safety. Several forms of surface translocation have been linked to biofilm formation. Biosurfactant production may be involved in sliding, which is produced by the expansive forces in a growing colony in combination with special surface properties of the cells, and in biofilm formation in B. cereus.; PlcR is a pleiotropic regulator in B. cereus that controls a variety of genes at the onset of stationary phase. The B. cereus ATCC 14579 DeltaplcR mutant formed more abundant biofilm than its wild-type. We found that PlcR may decrease the production of a biosurfactant, which is required for biofilm formation and sliding. Delta plcR mutant formed dendritic patterns on EPS (low nutrient) agar via sliding translocation due to its production of biosurfactant. This biosurfactant was identified as a lipopeptide and has a mass of 1278.1722 (m/z). It was shown to have hemolytic activity and inhibited the growth of several gram-positive bacteria.; In order to understand biofilm formation in B. cereus, a high biofilm producing strain UW101C was used. A codY transposon mutant was identified, which attached less, detached earlier, and produced four-fold lower biofilm than the wild-type. CodY is a global regulator that represses many genes in exponential phase. It appears CodY may repress a ∼130 kDa protease that contributes to biofilm detachment. B. cereus CodY can replace B. subtilis CodY and senses amino acid and GTP levels. These data suggest that CodY represses the production of an unknown protease and is involved in biofilm formation.