Effect of different microbial concentrations on binding of aflatoxin M₁ and stability testing

Aflatoxin M₁ (AFM₁) is a group 2b category carcinogenic compound of global concern due to its occurrence in milk. Various microbes have been employed for the binding of AFM₁ and to reduce its bioavailability in humans. In the current study three strains of lactic acid bacteria, a strain of Saccharomyces cerevisiae and a mixture of all four were used to evaluate their binding potentials for AFM₁. Milk samples were spiked with two different concentrations of AFM₁, 0.05 and 0.1 μg/l, and four concentrations of microbes, 10⁷, 10⁸, 10⁹ and 10¹⁰ cfu/ml, were tested to evaluate their binding potentials. The concentration of AFM₁ and microbes were found to significantly affect the binding potentials of microbes. Saccharomyces cerevisiae, Lactobacillus helveticus and the mixture of microbes at the concentration of 10¹⁰ cfu/ml resulted in 100% binding of AFM₁. Lactobacillus helveticus was found to have a higher binding potential than any other lactic acid bacteria reported previously. The binding of AFM₁ with microbes was reversible as the washing test resulted in ∼20–∼70% release of AFM₁. These results indicate that the microbes can be effectively used for the reduction of AFM₁ levels up to safe limits in milk and milk products.