Antifungal and mycotoxin detoxification potentials of Acetobacter tropicalis AT7 and Lactiplantibacillus plantarum LP64 in whole-plant corn silage

Whole-plant corn silage is an important forage for ruminant livestock; however, it is vulnerable to contamination by spoilage molds and mycotoxins because corn is an excellent substrate for fungal growth. Mycotoxins in corn silage have been found to significantly impair the productivity, health status, and fertility of dairy herds. It is urgent to develop a biological control strategy to prevent toxigenic fungi and mitigate mycotoxins in silage. This study aimed to evaluate the biocontrol potential of two novel isolated strains against toxigenic fungi and their toxins in corn silage. Acetobacter tropicalis AT7 and Lactiplantibacillus plantarum LP64 were isolated from mold-contaminated silages based on their potential antifungal and detoxifying properties. The antifungal activity of the two strains was affected by pH and heating, the antifungal compounds against A. flavus might be proteinaceous substances. The supernatants and cell pellets of the two isolates exhibited mycotoxin removal abilities for Aflatoxin B1 (AFB1), Zearalenone (ZEN), and Deoxynivalenol (DON), indicating that both adsorption and biodegradation contributed to mycotoxin detoxification. The two strains were ensiled with artificial fungal-infected (FI) or non-fungal-infected (NFI) whole-plant corn for 180 d. The FI silages had higher concentrations of aflatoxin B1 and deoxynivalenol than NFI silages. Both A. tropicalis AT7 and L. plantarum LP64 decreased aflatoxin B1 and zearalenone concentrations. Two strains affected the bacterial and fungal communities during the ensiling, indicated by the decline in the relative abundance (RA) of Pseudopithomyces and Periconia as compared to untreated corn silages. Inoculating A. tropicalis AT7 increased microbial network stability of NFI silage. In summary, A. tropicalis AT7 has the potential to be used as a biological preservative for reducing mycotoxigenic fungi and mycotoxin contamination in silages.