In vitro efficacy of two microbial strains and physicochemical effects on their aflatoxin decontamination in poultry feeds

The efficacy of two microbial isolates, Bacillus spp. (B285) and Saccharomyces spp. yeast strain (Y833), in reducing aflatoxin concentration in poultry feeds in comparison with the commonly used commercial chemical binder, bentonite, was investigated using the VICAM ® fluorometer. The influence of the poultry feed matrix, pH (4.5 and 6.5), and temperature (room temperature, 37 and 42oC) on the aflatoxin reducing activity by the two microorganisms was also explored. All microorganisms and bentonite reduced aflatoxins by over 74% of the original concentration. Bentonite registered the highest reduction at 93.4%; followed by Y833 (83.6%), then the combination of Y833 and B285 (77.9%); and lastly B285 (74.9%). Temperature and pH did not have significant effect on the performance of the biological agents and bentonite. The aflatoxin reducing activity was lower in presence of feeds compared to that in phosphate buffered saline except for Y833. The yeast strain was more effective than the bacterial strain in reducing the aflatoxin levels; however, both are promising strategies for countering the aflatoxin challenges in animal feeds. In response to the advocacy for use of biological control agents, there is need for more investigations to establish the safety of the microorganisms and the mechanism of aflatoxin decontamination.   Key words: Aflatoxin decontamination, Saccharomyces, Bacillus, commercial binder, animal feeds, pH, temperature.