Inhibition ofAspergillus flavus growth and aflatoxin B1 production by natamycin

Abstract

Aspergillus flavus causes huge crop losses, reduces crop quality and has adverse effects on human and animal health. A large amount of food contaminated with aflatoxin can greatly increase the risk of liver cancer. Therefore, prevention and control of aflatoxin production have aroused attention of research in various countries. Natamycin extracted fromStreptomyces spp. has been widely used in production practice due to its good specificity and safety. Here, we found that natamycin could significantly inhibit fungal growth, conidia germination, ergosterol and AFB1 production byA. flavus in a dose-dependent manner. Scanning electron microscope analysis indicated that the number of conidia was decreased, the outer wall of conidia was destroyed, and the mycelia were shrivelled and tangled by natamycin. RNA-Seq data indicated that natamycin inhibited fungal growth and conidia development ofA. flavus by significantly down-regulating some genes involved in ergosterol biosynthesis, such asErg13,HMG1 andHMG2. It inhibited conidia germination by significantly down-regulating some genes related to conidia development, such asFluG andVosA. After natamycin exposure, the decreased ratio ofaflS/aflR caused by the down-regulation of all the structural genes, which subsequently resulted in the suppression of AFB1 production. In conclusion, this study served to reveal the inhibitory mechanisms of natamycin on fungal growth and AFB1 biosynthesis inA. flavus and to provide solid evidence for its application in controlling AFB1 contamination.