SELECTION OF LACTOBACILLUS MUTANTS FOR THEIR ALPHA-DICARBONYL PRODUCTION

A method was devised for detecting Lactobacillus mutants that produced amounts of dicarbonyl compounds different from those of their parents. The mutants were recognized by contacting colonies with glass filter paper, which later was sprayed with a solution of o-dianisidine and heated. The amount of dicarbonyl could be estimated by the intensity of the resulting brown spots. The amounts of glyoxal, methylglyoxal, and diacetyl produced by mutants and parents were determined by a high performance chromatography method after growth on two media. Mutants that differed in the production of all three dicarbonyls were noted. The expression of the mutation varied with the medium used. © 1990, American Dairy Science Association. All rights reserved.