Aflatoxins are secondary metabolites produced by some competent mould strains
of Aspergillus flavus, A. parasiticus and A. nomius. These compounds have been
extensively studied with regards to their toxicity for animals and humans; they are able to
induce liver cancer and may cause a wide range of adverse effects in 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. Mould growth is conditioned by many
ecological factors, including biotic ones. Hazard characterization models for aflatoxins in
crops must take into consideration biotic interactions between moulds and their potential
effects on 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
laboratory model used was a natural matrix (humidified cracked corn), on which each wild
strain challenged the aflatoxin production of a producer strain. Cultures were incubated at 28ºC for 12 days and sampled at the 8th and 12th. Aflatoxin 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 antagonistic effects on aflatoxin biosynthesis.
Productivity increases were particularly evident on the 8th day of incubation with wild
strains of A. flavipes (+ 70.4 % ), A. versicolor (+ 54.9 %) and A. flavus 3 (+ 62.6 %).
Antagonistic effects were found with A. niger (- 69.5%) , A. fumigatus (- 47.6 %) and A.
terreus (- 47.6 %) on the 12th day. The increased effects were more evident on the 8th of
incubation and the decreases were more patent on the 12th day. Results show that the
development of Aspergilla strains concomitantly with competent aflatoxin producing
moulds has a significant influence on the natural biosynthesis pattern.