Anti-aflatoxigenic activity of Lactobacillus casei pseudoplantarum

Lactobacillus casei pseudoplantarum 371 isolated from a silage inoculant was found to inhibit aflatoxins B1 and G1 biosynthesis by Aspergillus flavus subsp. parasiticus NRRL 2999, in liquid medium. The inhibitory activity in the Lactobacillus cell-free supernatant was found to be sensitive to proteolytic enzymes such as trypsin and α-chymotrypsin, but resistant to pepsin. Lab-Lemco tryptone broth (LTB), supplemented with 20% of dialyzed protein concentrate of the supernatant, totally inhibited the production of aflatoxins B1 and G1. When the protein concentrate was digested with trypsin, the production of aflatoxins B1 and G1 was restored. The inhibitory activity of the supernatant was inactivated within 10 min at 100 °C. A. flavus grown in the Lactobacillus cell-free supernatant did not produce a mutagenic response in the Salmonella mutagenicity test. However, Lactobacillus casei pseudoplantarum 371 did not have an effect on aflatoxin production and mold growth as measured by ergosterol and plate count, when the organisms were inoculated together on sterile steamed rice.