Single bacteriocin typing scheme for the vibrio group of organisms

A total of 743 strains of O-I "agglutinable" and 293 strains of O I "inagglutinable" Vibrio cholerae were subjected to bacteriocin typing based on deferred antagonism of eight indicator bacteria, including two strains of V. cholerae, by the method of Chakrabarty et al. (Infect. Immun. 1:293-299, 1970). A minor modification that was effected in the typing medium was replacement of iodoacetic acid by ammonium chloride (at a final concentration of 0.003%) which appeared to regulate bacteriocin production more accurately and increase the stability of the types. Of the agglutinable strains, 94% were found to be bacteriocinogenic and could be fitted into 11 of the earlier-reported types (Chakrabarty et al., Infect. Immun. 1:293-299, 1970), and 6 newer types were recognized. Likewise, 285 (90.7%) of the inagglutinable strains were found to be bacteriocinogenic and could be accommodated within 10 original and 8 newer types identified for the inagglutinable vibrios. Thirteen types were common to the two groups of vibrios. The single bacteriocin typing scheme appeared to be simple and adequate for both groups of organisms, and the producer as well as the indicator bacteria behaved remarkably stably in this typing scheme over many years.