Development of a droplet digital PCR assay for population analysis of aflatoxigenic and atoxigenic Aspergillus flavus mixtures in soil

AbstractAflatoxin B1 is a potent hepatotoxin and carcinogen that poses a serious safety hazard to both humans and animals.Aspergillus flavus is the most common aflatoxin-producing species on corn, cotton, peanuts, and tree nuts. Application of atoxigenic strains to compete against aflatoxigenic strains ofA. flavus has emerged as one of the most practical strategies for ameliorating aflatoxin contamination in food. Genes directly involved in aflatoxin biosynthesis are clustered on an 82-kb region of the genome. Three atoxigenic strains (CA12, M34, and AF123) were each paired with each of four aflatoxigenic strains (CA28, CA42, CA90, and M52), inoculated into soil and incubated at 28  °C for 2 weeks and 1 month. TaqMan probes, omtA-FAM, and norA-HEX were designed for developing a droplet digital PCR (ddPCR) assay to analyze the soil population of mixtures ofA. flavus strains. DNA was extracted from each soil sample and used for ddPCR assays. The data indicated that competition between atoxigenic and aflatoxigenic was strain dependent. Variation in competitive ability among different strains ofA. flavus influenced the population reduction of the aflatoxigenic strain by the atoxigenic strain. Higher ratios of atoxigenic to aflatoxigenic strains increased soil population of atoxigenic strains. This is the first study to demonstrate the utility of ddPCR to quantify mixtures of both atoxigenic and aflatoxigenicA. flavus strains in soil and allows for rapid and accurate determina...
Source: Mycotoxin Research - Category: Toxicology Source Type: research