Analysis of fumonisin B 1 removal by microorganisms in co-occurrence with aflatoxin B 1 and the nature of the binding process

Abstract

The objectives of this investigation were to evaluate the ability of Saccharomyces cerevisiae CECT 1891 and Lactobacillus acidophilus 24 to remove fumonisin B1 (FB1) from liquid medium; to determine the nature of the mechanism involved in FB1?microorganism interaction and to analyze whether the presence of aflatoxin B1 (AFB1) interferes with the removal of FB1 and vice versa. The results obtained indicated that: (i) both microorganisms were able to remove FB1 from liquid medium; (ii) the removal was a fast and reversible process; (iii) cell viability was not necessary; (iv) the amount of FB1 removed was both toxin- and microorganism concentration-dependent; (v) the process did not involve chemical modification of FB1 molecules; and (vi) cell wall structural integrity of the microorganisms was required for FB1 removal. Consequently, we propose that the mechanism involved in the removal of FB1 is a physical adsorption (physisorption) of the toxin molecule to cell wall components of the microorganisms. It is highly probable that FB1 and AFB1 co-occur in contaminated foods, since the fungal genera Aspergillus and Fusarium frequently occur simultaneously. Therefore, we analyzed whether the presence of AFB1 interferes with the removal of FB1 by the microorganisms previously evaluated, and vice versa. Studies of co-occurrence of both mycotoxins clearly showed that they did not compete for binding sites on the microorganism cell wall and the presence of one toxin did not modify the efficiency of the organism in the removal of the other mycotoxin. These findings may be useful for optimization of mycotoxin binding and provide an important contribution to research on microorganisms with ability to remove these secondary metabolites.