Key role of teichoic acids on aflatoxin B1 binding by probiotic bacteria

Aims: To assess the ability of five probiotic bacteria to bind aflatoxin B-1 and to determine the key role of teichoic acids in the binding mechanism. Methods and Results: The strains were incubated in aqueous solutions containing aflatoxin B-1 (AFB(1)). The amount of free toxin was quantified by HPLC. Stability of the bacteria-aflatoxin complex was evaluated by repeated washes with buffer. In order to understand the binding process, protoplasts, spheroplasts and cell wall components of two strains were analysed to assess their capacity to bind AFB(1). Additionally, the role of teichoic acids in the AFB(1) binding process was assessed. Lactobacillus reuteri strain NRRL14171 and Lacto-bacillus casei strain Shirota were the most efficient strains for binding AFB(1). The stability of the AFB(1)-bacteria complex appears to be related to the binding ability of a particular strain; AFB(1) binding was also pH-dependent. Our results suggest that teichoic acids could be responsible for this ability. Conclusions: Our results provide information concerning AFB(1) binding by previously untested strains, leading to enhanced understanding of the mechanism by which probiotic bacteria bind AFB(1). Significance and Impact of the Study: Our results support the suggestion that some probiotic bacteria could prevent absorption of aflatoxin from the gastrointestinal tract.