Optimal percentage of NaCl for V cholerae -

Ans. is 'a' i.e., 1% VIBRIO CHOLERAEo MorphologyGram negativeBacilliNon capsulatedComma shapedS-shaped or spiral form may be seen.Arranged in parallel rows - Fish in stream appearance.Motile by polar flegellum - Darting type motility.Actively motile vibrios suggest a 'Swarm of gnats'o Culture characteristicStrongly aerobic (obligate aerobe)Growth is better in alkaline medium (pH 6-4-9.6)0'5-l% 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, infundibuliform (funnelshaped) or napiform (turnip shaped) liquefaction occur.Remembero While 0-5-1% NaCl is required for optimal growth, 6% or above NaCl inhibits the growth.