title: Efficacy of the Ryu nonstaining KOH technique for rapidly determining gram reactions of food-borne and waterborne bacteria and yeasts.
abstract: 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.
mesh_terms: D000818:Animals; D005069:Evaluation Studies as Topic; D005516:Food Microbiology; D005840:Gentian Violet; D006090:Gram-Negative Bacteria / Q000302:isolation & purification; D006094:Gram-Positive Bacteria / Q000302:isolation & purification; D006801:Humans; D006878:Hydroxides; D008828:Microbiological Techniques; D010619:Phenazines; D017680:Potassium Compounds; D014871:Water Microbiology; D015003:Yeasts / Q000302:isolation & purification
chemical_list: C035863:Gram's stain; D006878:Hydroxides; D010619:Phenazines; D017680:Potassium Compounds; D005840:Gentian Violet; C029943:potassium hydroxide