, Diagnosis an-&& of Shrimp Diseases - Central Institute of ...

Iizterpretation: Development of pink colour indicates a positive reaction.Voges Proscauer? TestPrinciple: The test detects acetoin or acetyl methyl carbinol, an intermediate product in theformation of butylene glycol during the metabolism of glucose. Acetoin is oxidised todiacetyl in the presence of oxygen by potassium or sodium hydroxide, which is a red colouredcomplex. Sensitivity of the test is further improved by addition of a-naphthol prior toaddition of KOH.Procedure:i. Grow pure culture of the bicteria in 5 ml of MRVP broth at 37°C for 48 h.ii. Transfer about 2.5 ml of culture to another tube.iii.Add 0.3 ml of.alcoholic a-naphthol and 0.1 ml of 40% KOH solution, gently agitate thetube and allow to stand for 10-15'.iv. Observe for formation of red colour.I~zterpretation: Developinent of red / crimson colour indicates that bacteria produce acetylmethyl carbinol.Salt tolerancePrinciple: Various species of Vibrio and related bacteria can be differentiated based on theirability to grow in the presence of different levels of sodium chloride.Procedure:Inoculate bacterial culture into nutrient broth tubes containing 0, 3, 6, 8 and 10% NaCI..I'Incubate at 37'C overnight and observe for growth, which is indicated by turbidity of thebroth, compared to uninoculated control.Sensitivity to 01129Prirzciple: Vibrio species are sensitive to 150 pg of 01129 (2,4 di amino, 6-7 di isopropylpteridine), while the other related genera like Pseudomonas, Aeromonas, Plesiomonas,