International Journal of Molecular Sciences (Mar 2008)
Interaction of Wild Strains of Aspergilla with Aspergillus parasiticus ATCC15517 on Aflatoxins Production
Abstract
Aflatoxins are secondary metabolites produced by some competent mould strains of Aspergillus flavus, A. parasiticus and A. nomius. These compounds have been extensively studied concerning its toxicity for animals and humans; they are able to induce liver cancer and caused a large range of adverse effects on living organisms. Aflatoxins are found as natural contaminants of food and feed; the main line of the strategy to control them is based on the prevention of the mould growth in raw vegetable or during its storage and monitoring of each crop batch. Moulds growth is conditioned by many ecological factors, including biotic one’s. Hazard characterization models for Aflatoxins in crops must take in consideration the biotic interaction that moulds establish between them on their growth development. The aim of this work is to study the effect of the biotic interaction of 14 different wild strains of Aspergilla (different species), with a competent strain (Aspergillus parasiticus ATCC 15517) using an in vitro production model. The laboratorial model concerns to a natural matrix (humidified cracked corn), in which each wild strain challenged the producer strain for Aflatoxins production. Cultures were incubated at 28ºC for 12 days and sampled at 8th and 12th. Aflatoxins detection and quantification was performed by HPLC using a procedure with a MRPL = 1 μg/kg. Results of those interactive cultures revealed both synergic and antagonist effects on the Aflatoxin biosynthesis. Productivity increases were particularly evident at 8th day of incubation with wild strains of A. flavipes (+ 70.4 % ), A. versicolor (+ 54.9 %) and A. flavus 3 (+ 62.6 %). Antagonist effects were found with A. niger (- 69.5%) , A. fumigatus (- 47.6 %) and A. terreus (- 47.6 %) at 12th day. The increasable effects were more evident at 8th of incubation and the decrease was more patent at the 12th day. Results show that the development of Aspergilla strains concomitantly with competent aflatoxins producer moulds has a significant influence on the natural biosynthesis pattern.
