Removal of aflatoxins by viable and heat-killed lactic acid bacteria and bifidobacteria

The contamination of food and animal feed with AFB(1) and AFM(1) is a worldwide problem. AFB(1) and AFM(1) are currently of great interest because of their toxic, carcinogenic and mutagenic potential on human and animal health. For this reason, there is a great demand for novel strategies to reduce or inactivate AFB(1) and AFM(1) The most recent approach for protecting humans against aflatoxins is the utilization of dairy strains of lactic acid bacteria which are supposed to bind aflatoxins efficiently in the human gastrointestinal tract. For this purpose, four dairy strains of lactic acid bacteria and four bifidobacteria, viable as well as heat-killed, were tested for their AFM(1) binding ability both in phosphate-buffered saline (PBS) and skim milk. Viable and heat-killed bacteria were incubated with 0.1 mug ml(-1) AFM(1) both in PBS and skim milk for 24 hours and the AFM(1) residue in the supernatant was measured using enzyme-linked immunosorbent assay. All viable and heat-killed strains were able to bind AFM(1) in PBS and skim milk. The binding abilities of AFM(1) by viable test strains were found to range from 22.9% to 45.3% and 19.3% to 38.3% for PBS and skim milk, respectively. Abilities of heat-treated strains to bind AFM(1) ranged from 31.3 to 61.9% and 24.6 to 51.5% for PBS and skim milk, respectively. Moreover, the abilities of five strains of viable probiotic bacteria to bind AFB(1) after 24 hours incubation with 1 mug ml(-1) AFB(1) were determined by thin-layer chromatography. The binding capacity was found to range from 81.0% to 46.5% and 29.5% to 38.5% for phosphate-buffered saline and reconstituted milk, respectively.