THE MALTOSE REGULON OF VIBRIO-CHOLERAE AFFECTS PRODUCTION AND SECRETION OF VIRULENCE FACTORS

The effects of maltose on production and secretion of virulence factor s of Vibrio cholerae in strain X28214, classical biotype, and in malto se-defective transposon mutants constructed from this strain were char acterized. Maltose was found to inhibit secretion of cholera toxin and to reduce production of the mannose-sensitive hemagglutinin and the s oluble hemagglutinin-protease. In contrast, the amount of toxin-coregu lated pilus was increased in the presence of maltose. The maltose effe ct was apparently mediated by genes of the maltose regulon, since inac tivation of the malQ or malF gene of V. cholerae by transposon inserti on was found to affect production and secretion of the same virulence factors that were responsive to maltose. The malQ and malF mutants sho wed, in addition, reduced virulence in an infant-mouse model. These re sults suggest that maltose may have a significant regulatory role in t he production of virulence factors and that an intact maltose regulon is needed for full virulence of V. cholerae.