Evaluation of Saccharomyces cerevisiae as an anti-fumonisin B-1 additive in a horse digestion model

Abstract

In this study, the capacity of Saccharomyces cerevisiae to adsorb fumonisin B-1 (FB1) was evaluated in in vitro assays. The digestion of nutrients from maize contaminated with FB1 was assessed as well as the influence of digestive enzymes and pH on the bioavailability of FB1 in solution. Adsorption assays in buffers containing 5 mu g/ml of FB1 were conducted to determine the strain to be used in the in vitro digestion assays. Four different yeast strains (1, 2, 3 and 4) along with five different cell concentrations of each one were studied under pH 2 and 6.8 at 39 degrees C. Strain 4 showed higher adsorption values at 1x10(9) cfu/ml, adsorbing 39.4% of the mycotoxin at pH 2 and 37.5% at pH 6.8. After that, the in vitro enzymatic digestion was conducted in two separated experiments. First, maize artificially contaminated with FB1 (5 mu g/g) was used in five different treatments. Then, assays with maize naturally contaminated with FB1 (Maize A: 3.2 mu g/g and Maize B: 29.0 mu g/g) were conducted. In all samples, FB1 was quantified by HPLC-FL in liquid fraction and in solid residue. Samples of maize in natura and solid residues were subjected to chemical analysis of dry matter, organic matter, crude protein, neutral detergent fibre and starch to estimate the digestion of nutrients. The presences of FB1 and S. cerevisiae (Strain 4) in these assays had no influence on the digestion of the maize nutrients. The adsorption capacity of yeast was observed more clearly in treatments with higher concentrations of FB1 in the maize grain. S. cerevisiae strain 4 removed between 8 to 18% of FB1 in solution, showing a limited capacity to adsorb FB1 under in vitro conditions of horse enzymatic digestion.