New perspectives for the application of bioplastic materials in the biocontrol of Aspergillus flavus in corn

Mycotoxins are secondary metabolites produced by certain filamentous fungi that can contaminate a large variety of agricultural commodities before and after harvest. Among different mycotoxins, aflatoxins and especially aflatoxin B1 are of particular concern because they are potent natural carcinogens. Aflatoxin-producing fungi, mainly Aspergillus flavus and A. parasiticus, are ubiquitous, being commonly isolated from agricultural soil and crop debris. Although many aspects of the ecology of aflatoxin-producing fungi have been elucidated, control of aflatoxin contamination of agricultural crops remains a difficult task. Agronomical practices promoting general plant health have shown variable and more frequently limited success in preharvest control of aflatoxin contamination. Competitive replacement of indigenous toxigenic soil isolates is considered a more promising and effective approach. This biocontrol strategy is based on field application of a large number of propagules of nontoxigenic strains of A. flavus. Biocontrol strains are typically formulated as inoculated or spore-coated grain seeds. More recently, efforts to explore new approaches and technologies have resulted in the development of other practical solutions, including a bioplastic-based formulation. This formulation originally developed in 2008, consists of bioplastic granules entrapping spores of the nontoxigenic biocontrol strain, A. flavus NRRL 30797. Laboratory and field studies that have been conducted until now have clearly shown that granules of the starch-based bioplastic Mater-Bi® are effective in delivering this biocontrol strain. In addition to having a satisfactory shelf life, the granules are easy to prepare, handle, and apply to agricultural fields. More importantly, this novel bioplastic formulation is capable of efficiently reducing aflatoxin contamination of corn. The bioplastic Mater-Bi® can also have other applications. For instance, rods or granules prepared using a slightly modified Mater-Bi® bioplastic matrix can be used to selectively isolate A. flavus from soil and corn kernels. © 2011 Informa Healthcare USA, Inc.