Adsorption of aflatoxins from a culture onto different bentonites

A. MAGNOLI; A. M. DALCERO; R. M. TORRES SANCHEZ; S. M. CHIACCHIERA; L. TALLONE

Carlos Paz

Conferencia; Advances in research on toxigenic fungi and mycotoxins in South America ensuring food and feed safety in a myco-globe context. Myco-Globe.; 2006

Unversidad de Rio Cuarto

The contamination of agricultural products with fungi are able to produce toxic metabolites is often unavoidable and of worldwide concern, Mycotoxins cause a wide variety of adverse clinical signs depending on its nature and concentration of toxins: in the diets, on animal species, on its age and on nutritional and health status at the time of exposure to contaminated-fedd. Aflatoxins (AF) are produced by the Aspergillus section Flavi A. Flavus and A parasiticus. They cause a variety of effects in poultry including the decrease in both the body weight gain and feed utilization efficiency. Aflatoxins B1,a cyclopentanone difurocoumarine is the most acutely toxic of the 16 naturally AF. In poultry, AFB1 is, associated with liver damage, poor performance and inmuno suppression. Definitive ways for complete detoxification of mycotoxins contaminated food and feed do not exist even though different methods to eliminate mycotoxicosis are known. The most popular seems to be the use of non nutritive additives to animal diets, that acts as sequestering agents which prevent the gastrointestinal adsorption of toxin. The efficacy of layered aluminosilicates such bentonites have been probed. In fact, they are already commercially used both, for detoxification of aflatoxin-contaminated feedstuffs and as binding agents for increasing the durability and palatability of the feed. However, the ability of these adsorbents may vary from different geological sources and even from different batch in in a given source. The scope of this study was to evaluate the affinity and capacity of three commercial bentonites to adsorb aflatoxins. In this study the mycotoxins were isothermally mixed with each adsorbent to study the adsorption process. S-type isotherms were characterized from all data. The effect of the pH upon the adsorption process was studied. Fowler-Guffenheim isotherm data fits showed attractive interactions among species on the solid surface. A multilayer adsorption mechanism seems to be operating for some of the bentonite samples. The maximum coverage for AFs varies with the SB. This fact seems to be correlated with a multilayer adsorption mechanism. The strength of the toxin-adsorbent interaction against the variation in the pH was evaluated by means of controlled pH extraction of the AFs-SB complexes. The observed finding were analyzed taking into account the structural characteristic of the adsorbent.