Isolation and characterization of the exo-enterotoxin of Vibrio cholerae strain 110 Cal

Vibrio Cholerae "strain 110 Cal" from Calabar, Nigeria were grown in syncase broth. Exo-enterotoxin secreted into the medium was then isolated purified and characterized. The toxin had enterotoxic activity using the infant mouseassay of World Health Organization. The toxin also had a molecular weight of about 89,000 daltons by gel filtration through sephadex G-150 and 100,000 daltons by polyacrylamide gel electrophoresis (PAGE). The toxin exhibited two subunits with molecular weights of about 63,000 and 31,000 daltons on SDS-PAGE. The toxin was resolved through sephadex G-150 into three peaks having molecular weights of about 89,000, 44,000 and 14,000 daltons respectively. The three peaks had enterotoxic activity. Each peak contained a single protein band on PAGE and SDS-PAGE showed that peak I consisted of two subunits with molecular weights of 56,000 and 31,000 daltons and peak II and III were monomers.