String test with Vibrio cholerae. The string test may be performed on plastic petri dish in a drop of 0.5% aqueous solution of sodium deoxycholate - the bacterial cells will be lysed by the sodium deoxycholate, the suspension will lose turbidity, and DNA will be released from the lysed cells causing the mixture to become viscous. Aeromonas strains are usually negative.

		Vibrio cholerae string test
		The string test may be performed on a glass microscope slide or plastic petri dish by suspending 18- to 24-hour growth from HIA or other noninhibitory medium in a drop of 0.5% aqueous solution of sodium deoxycholate. If the result is positive, the bacterial cells will be lysed by the sodium deoxycholate, the suspension will lose turbidity, and DNA will be released from the lysed cells causing the mixture to become viscous. A mucoid “string” is formed when an inoculating loop is drawn slowly away from the suspension. Most vibrios are positive, whereas Aeromonas strains are usually negative. Text: CDC
Microscopy: Gram-negative, curved, non-spore-forming rods.

Vibrio cholerae string test