Inhibition of Aflatoxin Production of Aspergillus flavus by Lactobacillus casei

Abstract

Lactobacillus casei KC-324 was tested for its ability to inhibit aflatoxin production and mycelial growth of Aspergillus flavus ATCC 15517 in liquid culture. Aflatoxin B₁ biosynthesis and mycelial growth were inhibited in both simultaneous culture and individual antagonism assays, suggesting that the inhibitory activity was due to extracellular metabolites produced in cell-free supernatant fluids of the cultured broth of L. casei KC-324. In cell-free supernatant fluids of all media tested, deMan, Rogosa and Sharpe broth, potato dextrose broth, and Czapek-Dox broth +1% yeast extract showed higher anti-aflatoxigenie activity. In these ease, fungal growths, however, was not affected as measured by mycelial dry weight. The anti-aflatoxigenie metabolites from L. casei KC-324 were produced over wide range of temperatures between 25°C and 3TC. However, these metabolites were not thermostable since the inhibitory activity of the supernatant was inactivated within 30 minutes at 100°C and 121°C. The inhibitory activity was not influenced by changing pH of supernatant between 4 and 10. However, the antiaflatoxigenic activity was slightly reduced at pH 10.

Keywords::

• Aflatoxin
• Antiaflatoxigenic metabolites
• Aspergillus flavus
• Lactobacillus casei