Antimicrobial substance produced by Lactobacillus helveticus 2700

Abstract

Fifteen lactic acid bacteria (LAB) were screened for their ability to produce antimicrobial substances against Lactobacillus delbrueckii ssp. bulgaricus 2519, Lactobacillus helveticus 2700, Lactobacillus casei 2603 and Lactobacillus jugurti 2819. Of the fifteen LAB, L. helveticus 2700, Lactobacillus plantarum 2903 and Lactobacillus fermentum 5174 exhibited antimicrobial activity. The characteristics of the antimicrobial substance produced by L. helveticus 2700 were studied. The antimicrobial substance produced in fermented milk by L. helveticus 2700 inhibited seven strains of L. delbrueckii ssp. bulgaricus, the producer organism L. helveticus 2700, 14 strains of L acidophilus and one strain each of L. plantarum 2903 and L. jugurti 2819, but not the other LAB, spoilage and pathogenic micro-organisms tested. The antimicrobial activity of L. helveticus 2700 was not due to organic acids or hydrogen peroxide. The molecular weight of the substance was less than 5000 daltons. The substance was active over a pH range of 3.0-10.0, and inactivation occurred at 70°C.