Use Of Lactobacillus Strains As A Strategy To Remove Fumonisins

Fumonisins, as one group of mycotoxins which often occur in corn and corn-related products, are very harmful to human beings and animals. Currently, removal of fumonisins from their environments mainly depends upon physical and chemical tools, and to date few reports on the use of microorganisms as biological agents to bind the mycotoxins have been described yet. This present study discussed the possibility of selected lactic acid bacteria in reducing fumonisins. Therefore, its major objectives were to:(1) select potential lactobacilli strains which are able to bind effectively fumonisins in terms of a combination of ELISA assay and HPLC method; (2) investigate the binding of two selected strains, i.e., Lactobacillus plantarum B7 and Lactobacillus pentosus X8 to fumonisins (FBI and FB2); (3) discuss the influences of pH, HCl, TCA, lysozyme on the binding of two strains to fumonisins; (4) evaluate the death rates of Caco-2 cells exposed to directly fumonisins and LAB-FBs; and (5) finally present the possible mechanisms of two lactobacilli strains to bind fumonisins. The following were main results.1. Two lactobacilli strains B7 and X8 showed the ablitiy to bind fumonisins B1 and B2. FBI-bound rate by strain B7 was 52.9% and 58% by strain X8. FB2-bound percentage was 85.2% for strain B7, and 86.5% for strain X8. More FB2 than FB1 was bound by two strains. The binding of fuminisins was strain-specific. Strain X8 was relately poor in binding FBI and FB2 than strain B7.2.5μg/mL of fumonisins had no effects on the growth of strains B7 and X8. The two strains still survived well after they were co-cultured with FBs at 37 ℃ for 1 h. They showed good viability when the cells of strains B7 and X8 bound fumonisins. However, Factors which included pH, chemical and enzymatic treatments, affected the bound ability of two strains. A decreasing pH led two strains to adsorb more fumonisins. As the pH was lowered, FB1-bound percentage of two strains was more than 50%, and FB2-bound percentage higher than 80%. The treatments of HCl and TCA promoted the binding ability of two strains to fumonisins, but using lysozyme to treat bacterial cells caused their fumonisins-binding ability to decrease.3. Caco-2 cell lines were used a model to exame the damage of fumonisins in the presence and absence of two lactobacilli strains in vitro. Supernatant collected from centrifugated strain B7-fuminisins reduced significantly the death percentage of CaCo-2 cells from 34.1% to 28.1%. Compared to the effect of fumonisins on CaCo-2 cells, the death percentage of CaCo-2 cells by strain X8-fumonisins was reduced from 34.1% to 21.9%. This data proved the removal ability of fumonisins via the binding of two strains B7 and X8.4. The binding site of strains-FBs probably lay in the peptidoglycans of cell wall. The peptidoglycans espeacially intact peptidoglycans which obtained from two strains B7 and X8 showed the strongest ability to bind fumonisins. The FBs-bound percentage reached 82.6% and 95.8% for strain B7, and 86.2% and 97.5% for strain X8, respectively. Additionally, the FBs-bound percentage by cell spheroplasts was less than 10%. Clearly, peptidoglycans, espeacially intact peptidoglycans played a key role in binding fumonisins.Briefly, L. plantarum B7 and L. pentosus X8 showed good ability to bind fumonisins. They should be good candidates as useful biological agents to reduce the occurance of the mycotoxins, and beneficial to the human body.