Physical Adsorption of Aflatoxin B1 by Lactic Acid Bacteria and Saccharomyces cerevisiae: A Theoretical Model

DANTE J. BUENO ,; CESAR H. CASALE; ROMINA P. PIZZOLITTO,; MARIO A. SALVANO; GUILLERMO OLIVER

JOURNAL OF FOOD PROTECTION

INT ASSOC FOOD PROTECTION

Año: 2007 vol. 90 p. 2148 - 2154

0362-028X

The ability of lactic acid bacteria (LAB) and Saccharomyces cerevisiae to remove aflatoxin B1 (AFB1) from liquid médium was tested. The experimental results indicated that (i) AFB1 binding to microorganisms was a rapid process (no more than 1min); (ii) this binding involved the formation of a reversible complex between the toxin and microorganism surface, without chemical modification of the toxin; (iii) the amount of AFB1 removed was both toxin- and bacteria concentration–dependent; and (iv) quantitatively similar results were obtained with viable and nonviable (heat-treated) bacteria. According to these details, a physical adsorption model is proposed for the binding of AFB1 to LAB and S. cerevisiae, considering that the binding (adsorption) and release (desorption) of AFB1 to and from the site on the surface of microorganism took place (AFB1 +S = S - AFB1). The model permits the estimation of two parameters: the number of binding sites per microorganism (M) and the reaction equilibrium constant (Keq) involved, both of which are useful for estimating the adsorption efficiency (M/Keq) of a particular microorganism. Application of the model to experimental data suggests that different microorganisms have similar Keq values and that the differences in toxin removal efficiency are mainly due to differences in M values. The most important application of the proposed model is the capacity to select the most efficient microorganism to remove AFB1. Furthermore, it allows us to know if a modification of the adsorption efficiency obtained by physical, chemical, or genetic treatments on the microorganism is a consequence of changes in M, Keq, or both.