In vitro aflatoxin B1 adsorption by Lactobacillus casei and Saccharomyces cerevisiae CECT 1891.

PIZZOLITTO, ROMINA; DALCERO ANA; SALVANO, MARIO

Huerta Grande Cba Argentina

Congreso; I Reunión Conjunta de Sociedades de Biología de la República Argentina; 2007

Glucomannan, peptidoglycans and polysaccharides present in the yeast and lactic acid bacteria cell wall, are able to remove aflatoxin B1 (AFB1) from liquid medium. Adsorption and release of toxin is a fast and reversible process, and does not involve AFB1 chemical modification. The amount of AFB1 removed is toxin and bacteria concentration-dependent and the same results are obtained with viable and non-viable bacteria. In this work L.casei (108 cells ml-1) and S. cerevisiae (107 cells ml-1) were incubated during 10 min at 37ºC in a shaking bath with 1 ml of PBS containing AFB1 (20-5000 ng ml-1). Later, the cells were pelleted by centrifugation at 5000 x g during 15 min and the supernatant, containing unbound AFB1, was analysed by HPLC. Under these conditions, both microorganisms showed a curve of toxin adsorption based on their concentration that was hyperbolic at low concentrations (0-500 ng ml-1) and sigmoid (cooperative effect) at high toxin concentrations (500-5000 ng ml-1). Thus, the efficiency (Keq x M) of both microorganisms showed an adaptation according to the added amount of AFB1. Although the Keq of the process was not significantly altered, the number of total adsorption sites by cell (M), was 12 times increased at high toxin concentrations. These results show the potential of L. casei and S. cerevisiae to allow the AFB1 detoxification.