COMPARATIVE-ANALYSIS OF FACTORS PROMOTING OPTIMAL PRODUCTION OF CHOLERA-TOXIN BY VIBRIO-CHOLERAE O1 (CLASSICAL AND ELTOR BIOTYPES) AND O139

Various culture media [AKI, Brain heart infusion broth (BHI), Casamino acid-yeast extract broth (CAYE), Casamino acid-yeast extract broth su pplemented with 90 mu g/ml of lincomycin (CAYE-L), Tryptic soy broth ( TSB) and Yeast extract peptone (YEP)], cultural conditions (stationary and shaking) and incubation temperatures (30 degrees C and 37 degrees C) were evaluated to determine optimal conditions for production of c holera toxin (CT) by different biotypes (classical and ElTor) and sero groups (O1 and O139) of V. cholerae. It was found that V. cholerae O1 ElTor grown in CAYE-L and incubated at 30 degrees C with constant shak ing was optimal for production of CT, while for the classical biotype and for the O139 serogroup, CT was maximally produced when grown in YE P and incubated at 30 degrees C in a shaker. Temperature appeared to b e a prominent factor affecting the production of CT by the O1 ElTor bi otype when the media used were AKI, CAYE-L and YEP and also for the cl assical biotype when the media used were the AKI, BHI, CAYE and YEP. I n the case of the O1 ElTor biotype, CAYE-L was the best medium for CT production whereas for the classical biotype, CAYE-L was a poor medium as far as CT production was concerned. Irrespective of the media used , 30 degrees C shake culture condition seemed to be more favourable fo r supporting CT production except in CAYE medium for the O1 ElTor biot ype where incubation at 37 degrees C in a shaker was as good as incuba tion at 30 degrees C.