title: Characterization of the codY gene and its influence on biofilm formation in Bacillus cereus.
abstract: The foodborne pathogen Bacillus cereus can form biofilms on various food contact surfaces, leading to contamination of food products. To study the mechanisms of biofilm formation by B. cereus, a Tn5401 library was generated from strain UW101C. Eight thousand mutants were screened in EPS, a low nutrient medium. One mutant (M124), with a disruption in codY, developed fourfold less biofilm than the wild-type, and its defective biofilm phenotype was rescued by complementation. Addition of 0.1% casamino acids to EPS prolonged the duration of biofilms in the wild-type but not codY mutant. When decoyinine, a GTP synthesis inhibitor, was added to EPS, biofilm formation was decreased in the wild-type but not the mutant. The codY mutant produced three times higher protease activity than the wild-type. Zymogram and SDS-PAGE data showed that production of the protease ( approximately 130 kDa) was repressed by CodY. Addition of proteinase K to EPS decreased biofilm formation by the wild-type. Using a dpp-lacZ fusion reporter system, it was shown that that the B. cereus CodY can sense amino acids and GTP levels. These data suggest that by responding to amino acids and intracellular GTP levels CodY represses production of an unknown protease and is involved in biofilm formation.
authors.affiliation: Department of Bacteriology, Food Research Institute, University of Wisconsin, Madison, WI 53706, USA.
authors.forename: Yi-Huang
authors.initials: YH
authors.lastname: Hsueh
authors.forename: Eileen B
authors.initials: EB
authors.lastname: Somers
authors.forename: Amy C Lee
authors.initials: AC
authors.lastname: Wong
mesh_terms: D001409:Bacillus cereus / Q000737:chemistry / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019286:Endopeptidase K / Q000494:pharmacology; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D008970:Molecular Weight; D016254:Mutagenesis, Insertional; D009876:Operon; D010447:Peptide Hydrolases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017422:Sequence Analysis, DNA
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D012097:Repressor Proteins; D010447:Peptide Hydrolases; D019286:Endopeptidase K