True about cholera vibrios is -: (A) Can tolerate wide range of alkaline pH, (B) Non motile bacilli, (C) Can't be grown in media, (D) All
Answer is A. Ans. is 'a' i.e., Can tolerate wide range of alkaline pH VIBRIO CHOLERAE Morphology - Gram negative - Bacilli - Non capsulated - Comma shaped - S-shaped or spiral form may be seen. - Arranged in parallel rows --> Fish in stream appearance. - Motile by polar flegellum ---> Daing type motility. - Actively motile vibrios suggest a 'Swarm of gnats' . Culture characteristic - Strongly aerobic (obligate aerobe) - Growth is better in alkaline medium (pH 6-4-9.6) - 0.5-1% Nacl is required for optimal growth. - MaConkeys agar --> Initial colourless colonies, later become reddish due to late lactose fermentation. - Blood agar --> Initially sorrounded by a zone of greening, which later become clear due to hemodigestion. - In gelatin stab culture, infundibulifornz (funnel shaped) or napiform (turnip shaped) liquefaction occur. Remember . While 0.5-1% NaCl is required for optimal growth, 6% or above NaCl inhibits the growth.