Industrial Microbiology

European journal of applied microbiology and biotechnology

, Volume 5, Issue 2, pp 123-127

First online:

Rapid method for distinction of gram-negative from gram-positive bacteria

  • T. GregersenAffiliated withVeterinary Faculty for F.A.O. Fellows, The Royal Veterinary and Agricultural University

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A rapid method for distinction between gram-negative and grampositive bacteria by means of a 3% solution of potassium hydroxide is tested on 71 gram-positive and 55 gram-negative bacterial strains. The method proved reliable with one exception only, a Bacillus macerans strain. That strain was definately gram-negative on staining. Other Bacillus strains were proved gram-positive by the test, even those being gram-negative on staining.