A strain of Aspergillus flavus from China shows potential as a biocontrol agent for aflatoxin contamination

Abstract

Aflatoxins are toxic and carcinogenic secondary metabolites produced by Aspergillus flavus and Aspergillus parasiticus. Strains of A. flavus that are non-aflatoxigenic (i.e., incapable of secreting aflatoxins) have proven effective in controlling contamination by these aflatoxin producing species in the field. In the present study, a non-aflatoxigenic A. flavus strain, GD-3, was isolated from a peanut field in Guangdong Province, China. Polymerase chain reaction (PCR) analysis showed that 12 aflatoxin biosynthesis genes (aflT, pksA, nor-1, fas-2, fas-1, aflR, aflJ, adhA, estA, norA, ver-1 and verA) were deleted in GD-3. Co-inoculation with a toxigenic strain, GD-15, at the ratio of 1:10, 1:1 or 10:1 (GD-3:GD-15), showed that GD-3 was capable of reducing detectable aflatoxin levels on three different substrates. This reduction ranged from 33% to 99% and correlated with competitor ratio. These results demonstrated that GD-3 was successful at reducing aflatoxin contamination and showed promise as a potential agent of biocontrol for local farmers.

Keywords:

• aflatoxin
• Aspergillus flavus
• atoxigenic strain
• aflatoxin gene cluster
• biocontrol

Acknowledgements

We are grateful to members of the Laboratory of Quality and Biosafety at Institute of Agro-products Processing Science and Technology, Chinese Academy of Agricultural Sciences for comments and participation in discussions.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This research was supported by the National Basic Research Program (973 Program) of China [grant number 2013CB127802], a Special Fund for Agro-scientific Research in the Public Interest (201203037) and the National Science Foundation of China (No. 31301478).