Chromosome Mobilization in Vibrio cholerae (biotype eltor) Mediated by Sex Factor P

Summary: Crosses between P+ strains of Vibrio cholerae (biotype ‘eltor’) and P− strains of V. cholerae (‘classical’) were infertile under conditions in which P+ × P− crosses of V. cholerae (‘classical’) strains were fertile. The efficiency of conjugation, as determined by the frequency of P transfer, was lower with P+ strains of the ‘eltor’ biotype compared with P+ strains of V. cholerae (‘classical’). However, incubation of P+ strains at 44·5°C, prior to mating, induced fertility in bacteria of the ‘eltor’ biotype and enhanced it in V. cholerae (‘classical’) crosses. It is suggested that new donors associated with a greater efficiency of conjugation are formed at 44·5°C in P+ strains of both biotypes.