Evaluation Of Surface Binding Of Aflatoxin B1 By Lactic Acid Bacteria And Saccharomyces cerevisiae.

PIZZOLITTO, R.,; CHIACCHIERA, S.; SALVANO M.

Villa Carlos Paz (Córdoba)

Congreso; Myco-globe; 2006

Universidad Nacional de Río Cuarto

Aflatoxins (AFs) are mycotoxins that cause health and economic problems when they contaminate food and feeds. They are synthesized as sencondary metabolites of toxigenic Aspergillus flavus, A. paraciticus and A. nomius strains (Peltronen et al., 2001). Once food is contaminated with aflatoxin, there are two options if the food is to be used: either the toxin is removed or the toxin is degraded into less toxic or non toxic compounds (El-Nezami et al., 1998). The control of AFs may be by pre- and postharvest methods and the last one can comprise the binding of AFs in the animal or human gut by lactic acid bacteria (LAB) (Bueno et al. 2001). Metabolic conversion and covalent binding of AFB1 by the bacteria have been excluded as a mechanism of removal, and non covalent binding of AFB1 to the bacterial surface has been proposed (Haskard et al., 2001; Lee et al., 2003). Furthermore, the cell wall peptidoglycan, or components bound covalently to peptidoglycan, are very important for AFB1 binding (Lahtinen et al., 2004) and the process involved could be more selective to AFs than some nutrients, for example vitamin B 12 (Turbic et al., 2002) In addition Saccharomyces cerevisiae and its cell wall component (mannanoligosaccharide) minimize the adverse effects of AFB1 in poultry, because they have a high affinity for the mycotoxins, both in vitro and within the intestinal tract (Yildiz et al., 2004) Objetive:  To determine if Lactobacillus casei (LC), Lactobacillus spp. (LV), Pediococcus B entosaceus (L8) and Saccharomyces cerevisiae could demostrate potencial antitoxin effects resulting from binding AFB1 and to asses the stability of the formed complexes. Conclutions: LAB strains and Saccharomyces cerevisiae are capable to remove AFB1 from liquid medium. The adsorption process is fast, c. a. 1 minute. The amount of bounded AFB1 was strain specific. Not viable and viable bacteria have the same ability to remove AFB1. The process is reversible. Co-operative effect allows to these microorganisms to capture AFs at high concentration levels. At low AFB1 concentration a physical adsorption mechanism seems to be operating, i.e. reversible adsorption