Factors affecting the removal of aflatoxin M₁ from food model by Lactobacillus and Bifidobacterium strains

Abstract

This paper describes the ability of six dairy strains of Lactobacillus and Bifidobacterium to remove aflatoxin M₁ (AFM₁) from phosphate-buffered saline (PBS) and reconstituted milk. Bacteria were incubated in both PBS and reconstituted milk containing 5, 10 and 20 ng mL⁻¹ for 0, 4 and 24 h at 37°C. After centrifugation the concentration of AFM₁ was determined in the supernatant fraction using high-performance liquid chromatography. The binding abilities of AFM₁ by viable (10⁸ CFU mL⁻¹) and heat-killed Lactobacillus and Bifidobacterium strains in PBS ranged from 10.22 to 26.65% and 14.04 to 28.97%, respectively. Similarly, AFM₁-binding capacity in reconstituted milk was found to range from 7.85 to 25.94% and from 12.85 to 27.31% for viable and heat-killed bacteria, respectively within 4 h. While B. bifidum Bb 13 was the best binder, the poorest removal was achieved by L. acidophilus NCC 68. Binding was reversible, and a small proportion of AFM₁ was released back into the solution. The toxin concentration and incubation period had no effect on the removal of AFM₁ by bacteria both in PBS and reconstituted milk.

Keywords:

• Aflatoxin M₁
• Lactobacillus
• Bifidobacterium
• removal
• high-performance liquid chromatography

Acknowledgments

This study was supported by the Cukurova University Research Council (project no: ZF2004D13). We greatly thank Prof. Hans P. van Egmond from National Institute for Public Health and the Environment for supplying the AFM₁ standard. We also thank A. Bozdogan for performing statistical analysis.