0 1987 The Pathological Society of Great Britain and Ireland Phage-induced change of toxigenesis in Vibrio cholerae

Summary. A temperate phage coding for constitutive hypertoxigenicity has been constructed in Vibrio cholerae strain 569B and used to lysogenise the low-toxin-producing strain MAK 757; 18 % of lysogens showed 10-100-fold increase in toxin production. This property was also transmitted at low frequency to second generation lysogens. Thus temperate phage can increase toxin production in a low-toxin-producing strain. Introduction Bhattacharyya, 1982). The preparation of phage @ and Pathogenic strains of Vibrio cholerae usually produce moderate levels of toxin in vitro whereas environmental strains do not. The possibility for evolution of a toxigenic variant from environmenta