Rice Weevil ( L.) Gut Bacteria Inhibit Growth of and Degrade Aflatoxin B1.

In this study, bacteria residing in the gut of the rice weevils ( L.) (Coleoptera: Curculionidae) feeding on aflatoxin-contaminated corn kernels were isolated and evaluated for their ability to suppress and to remove/degrade aflatoxin B1 (AFB1). Four morphologically distinct gut-associated bacterial isolates were isolated and identified as (RWGB1), (RWGB2), (RWGB3), and (RWGB4) based on 16S rRNA gene sequence analysis. These bacterial isolates inhibited growth in the dual culture assay and induced morphological deformities in the fungal hyphae, as confirmed by scanning electron microscopy. All four bacterial isolates were capable of removing AFB1 from the nutrient broth medium. In addition, culture supernatants of these bacterial isolates degraded AFB1, and the degradation of toxin molecules was confirmed by liquid chromatography-mass spectrometry. The bacterial isolates, RWGB1, RWGB2, and RWGB4, were capable of producing antifungal volatile organic compounds that inhibited growth. These results suggest that the bacterial isolates from gut have the potential to bind and/or degrade AFB1. Further research on their application in the food and feed industries could enhance the safety of food and feed production.