True about cholera vibrios is -

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.