Novel Approaches Using Water Potential and Antagonistic Bacteria, to Reduce <i>Aspergillus flavus</i> Population in Soil

The peanut market in the United States is expected to reach $81 billion dollars in 2025 and the state of Georgia is the main producer. Frequent contamination of peanuts with aflatoxins due to pre and postharvest fungal infection, mainly with Aspergillus flavus, results in up to 30% rejection of shelled runner peanuts. Most studies to mitigate aflatoxins have been focused on peanut varieties and plant responses to environmental stress such as drought and temperature. Despite A. flavus being present in all USA peanut growing soils, information on management of A. flavus populations in soil is scarce. In this study, we designed and implemented a controlled environment system to assess soil water potential (SWP) and soil amendment with antagonistic Bacillus subtilis for monitoring A. flavus populations in soil over time. We found that saturated soil (0 kPa) conditions led to decreased A. flavus titers compared to dryer conditions (30 – 1000) kPa; whereas soil amendment with B. subtilis did not significantly affect A. flavus counts. This method will facilitate further research into strategies to reduce aflatoxigenic Aspergilli in soil and potentially minimize pre-harvest aflatoxin accumulation.