Effect of extracellular protease production on bacteriophage sensitivity of Vibrio cholerae

The effect of varying levels of extracellular protease production on the bacteriophage type of Vibrio cholerae 1621 serotype 01, biotype E1 Tor, has been investigated. It has been shown that the production of high levels of exoprotease can alter the apparent type of the strain by rendering it insensitive to infection by a number of bacteriophages. Prevention of a productive infection appears to be due to altered surface characteristics rather than to specific damage to the bacteriophages. Such altered surface characteristics may be due to auto-digestion. The importance of this observation to epidemiological studies of V. cholerae is noted and discussed.