Soil Microbial Communities in Corn Fields Treated with Atoxigenic Aspergillus flavus

Abstract

Aspergillus flavus refers to a diverse group of saprophytic soil fungi that includes strains producing aflatoxins (toxigenic strains) in the kernels of corn (Zea mays L.) and other crops, causing pre-harvest and post-harvest aflatoxin contamination. Some A. flavus strains are atoxigenic, and the introduction of such strains into the crop environment helps reduce toxigenic aflatoxin contamination. Corn growers in Texas have used the product FourSure™, which contains four atoxigenic strains of A. flavus; however, effects on soil microbial communities associated with these applications are unknown. We compared soil fungal and bacterial communities in corn fields treated with FourSure™ to nearby untreated (control) corn fields in Texas during the summer of 2019. Analysis of soil microbial community structure showed that total fatty acid methyl esters (FAMEs), fungal, and bacterial populations were not significantly different (p = 0.31) between the FourSure™-treated and control fields, yet corn fields located in the northern counties had more (p < 0.05) Gram—bacteria, actinobacteria, and total bacteria than fields in the southernmost county. The Gram—bacteria and actinobacteria were positively correlated (p = 0.04; r = 0.48 and 0.49, respectively) with soil water content. Similar fungal and bacterial abundances between FourSure™-treated and control fields indicated that atoxigenic A. flavus had no negative effects on soil microbial communities.