Lactic acid bacteria with promising AFB1 binding properties as an alternative strategy to mitigate contamination on brewers’ grains

Abstract

Adsorption of molecules to the cell walls of microorganisms plays an important role in helping to prevent animal exposure to the toxic and carcinogenic effects of aflatoxins (AFs). The aim of this study was to evaluate the ability of LAB strains, isolated from brewers’ grains, to adsorb aflatoxin B1 (AFB1). All LAB were able to reduce the bioavailability of AFB1 from phosphate buffered-saline (PBS). In addition, the strains retained their effectiveness even after heat treatment. The AFB1-LAB complex stability was first evaluated through sequential washing steps. These assays demonstrated that a low percentage of AFB1 was released after consecutive washes. After subjecting the complex to different pH and bile salt treatments, the percentage of bound AF decreased, as compared to the control, but remained at high levels. Finally, to simulate the formation of the AFB1-LAB complex at conditions similar to those of the gastrointestinal tract, LAB and AFB1 were homogenized in PBS adjusted at acidic conditions or under different bile salt concentrations. In general, LAB strains showed the highest AFB1 adsorption at the lowest pH (2) and bile salt concentration (0.05%). In conclusion, the studied strains represent promising biocontrol agents for preventing and/or ameliorating the AFB1 contamination of feed.