Fumonisin B1 Binding by Saccharomyces cerevisiae CECT 1891 and Lactobacillus acidophilus 24: Mechanism Involved and Potential Protection Against Fumotoxicosis and Aflatoxicosis Simultaneously

PIZZOLITTO R. P.; DALCERO A. M,; SALVANO M.

Mendoza

Congreso; MycoRed ISM conference. Strategies to reduce the impact of mycotoxins in Latin America in a global context; 2011

UNRC

Aims: To investigate the remotion capacity of fumonisin B1 (FB1) by Saccharomyces cerevisiae CECT 1891 and Lactobacillus acidophilus 24 from liquid medium, since both microorganisms have been previously reported by their high efficiency to remove aflatoxin B1 (AFB1). To know the mechanism involved in FB1-microorganism interaction and the performance of these microorganisms if in the liquid medium AFB1 and FB1 co-occur. Methods and results: The ability of both microorganisms to remove FB1 from liquid medium was tested. Cells, at the necessary concentration, were suspended in phosphate-buffered saline (PBS) in the presence of different amounts of FB1 and incubated during the indicated time, at 37 °C. Then, the microorganisms were pelleted by centrifugation, the supernatants were collected and the free FB1 was quantified by HPLC. The influence of time contact, cell concentration, fumonisin B1 concentration, cell viability, release of FB1 bound to cells and the importance of the cell wall integrity of the microorganisms on the FB1 remotion, were evaluated. The results indicated that: (i) both microorganisms were able to remove fumonisin B1 from liquid medium; (ii) the removal was a fast and reversible process; (iii) the cell viability was not necessary; (iv) the amount of FB1 removed was both toxin- and microorganism concentration-dependent, but although the removal of mycotoxin increased with the cell concentration, this was never enough to remove all  environmental FB1; (v) the process did not involve chemical modification of FB1 molecules; and (vi) the cell wall structural integrity of the microorganisms was required for the FB1 remotion. Accordingly, we propose that the mechanism involved in the removal of fumonisin B1 by these microorganisms is a PHYSICAL ADSORPTION (physisorption) of the toxin molecule to cell wall components of the microorganisms.  This mechanism is the same proposed for AFB1 remotion, and as these microorganisms showed high ability to remove this toxin too, assays with both mycotoxins in co-occurrence were performed, showing that FB1 and AFB1 are bound to different adsorption sites located on the cell wall of the microorganisms. In addition, S. cerevisiae CECT 1891, the microorganism with the largest area of contact, was always more efficient than L. acidophilus 24 in the remotion of both mycotoxins, suggesting that binding efficiency is a more quantitative phenomenon (large surface area) than a qualitative phenomenon (chemical structure involved in the interaction). Conclusion: These microorganisms are efficient in the remotion of aflatoxin B1 and fumonisin B1, but occupying different binding sites in the cell wall, therefore the physical adsorption is independent even with co-occurrence of both mycotoxins. Thus, the inclusion of any of these microorganisms in the animal diet is potentially able to protect against aflatoxicosis and fumotoxicosis simultaneously.