Conversion of Vibrio eltor MAK757 to classical biotype: Role of phage PS166

Temperate phage PS166 infection of Vibrio eitor MAK757 resulted in complete changes in all biotype-specific determinants. About 10% of the PS166 lysog ens of MAK757 lost their eltor-specific determinants, namely, the ability t o produce soluble hemolysin, cell-associated hemagglutinin for chicken eryt hrocytes, and resistance to polymyxin B, as well as resistance to Mukherjee 's group IV phage and sensitivity to eitor phage e4. These lysogens were fo und to have acquired the properties of classical strains, most significantl y becoming sensitive to group IV phage but resistant to eltor-specific e4. The remainder of these lysogens, however, retained their parental biotype a nd serotype but acquired auxotrophy for glycine and histidine. The differen tial behavior of the two types of lysogen was due to the integration of the phage PS166 genome at different locations in the host chromosome. A 800-bp Bg/11 fragment was found to contain the attP site. Phage PS166 has a polyh edral head (95 nm in diameter) and a contractile tail (98 nm in length). Th e phage chromosome is a linear double-stranded DNA of 110 kb and a G + C co ntent of 58.7%. (C) 2000 Academic Press.