EFFICACY OF THE RYU NONSTAINING KOH TECHNIQUE FOR RAPIDLY DETERMINING GRAM REACTIONS OF FOOD-BORNE AND WATERBORNE BACTERIA AND YEASTS

A simple and rapid (< 60 s) nonstaining technique with 3% potassium hydroxide to determine Gram reactions was tested with 495 food-borne and waterborne bacteria and yeasts. In KOH, suspensions of gram-negative bacteria become viscous and string out. Gram-positive bacteria are not affected. There was 100% correlation between the KOH string test results and gram-positive and gram-negative strains.