Soil Microbial Responses to Aflatoxin Exposure: Consequences for Biomass, Activity and Catabolic Functionality

Aflatoxins (AFs) are fungal secondary metabolites frequently detected in soil that exhibit vitro toxicity to certain microorganisms. However, microbial responses at different levels and complex systems such as the environment have not been systematically studied. Therefore, we investigated multiple two soils (sandy loam clay) aflatoxin B1 (AFB1) environmentally relevant concentrations (0.5–500 µg kg−1) during a 28-day incubation. General parameters for biomass (microbial carbon ergosterol), activity (glucose-induced basal respiration), catabolic functionality (substrate utilization patterns) were assessed. We observed minor transient effects both soils. In sandy loam, found negative on with increased metabolic quotient, while clay exhibited stimulation same parameters, suggesting hormetic effect due reduced bioavailability through sorption onto minerals. Our results indicate AFB1 does pose threat general indicators under test conditions without previous AF contamination. Given toxic potential of AFs specific microorganisms, further studies should investigate higher taxonomic functional natural environments aflatoxigenic fungi, tropical soils, including additional physicochemical stressors.