Potential of biocontrol agents, antioxidant compounds and natural extracts on aflatoxin containment: a simple and highthroughput procedure

Aflatoxin B1 is considered one of the most dangerous mycotoxin for humans and animals health. Moreover severe economic losses may be encountered due to its possible contamination of food and feed during each step of their transformation process (from field to table). Preventing fungal infection/ toxin contamination of crops in the field is considered the preferred strategy to cope with the “aflatoxin risk”. Biocontrol by competitive inhibition using atoxigenic (afla–) Aspergillus flavus strains has been shown to be an effective method in aflatoxin containment in peanuts, maize and cottonseed(1). Naturally occurring populations of afla– strains are considered reservoirs from which to select the strongest biocompetitors. However, the selection of biocontrol strains is not an easy task, due both to the small amount of afla– strains and to the various environmental conditions that may affect their efficacy in the field(2). High throughput procedures are therefore desirable to screen large amount of isolates in order to identify “good competitors”. Moreover, as field trials required to assess their efficiency are expensive and laborious, reconstruction experiments have been generally performed under laboratory conditions to investigate the biological mechanisms underlying the efficacy of afla– strains in preventing aflatoxin production and/or to give a preliminary indication of strain performance when released in the crops. We developed a simple and inexpensive fluorescence-based procedure that may be used: 1) to scale-up the screening process(3) and also 2) to increase knowledge on the mechanisms interfering with mycotoxin production during intraspecific competition and 3) to analyze the effect of natural and/or synthetic compounds for their possible effects on aflatoxin biosynthesis. Here we give a report of our results concerning the evaluation of the potential of afla– strains, colonizing the corn fields of the Po Valley, in reducing aflatoxin accumulation, and show some preliminary evidence that suggest the possible use of antioxidants as part of an additional strategy to contain aflatoxin contamination of food and feed commodities. Conversely the procedure may be used to uncover the presence of antioxidant agents in complex mixtures deriving from natural sources.