Rhodococcus turbidus PD630 enables efficient biodegradation of aflatoxin B1

Abstract

Microbial degradation is a promising method for eliminating aflatoxin B1 (AFB1). In this study, we used a co-culture method to screen for microorganisms capable of efficiently degrading AFB1 and identified the strain Rhodococcus turbidus PD630 as a highly effective degrader. Our results demonstrated that PD630 had a high degradation efficiency, and the degradation efficiency of PD630 strain could be further enhanced by AFB1 induction or change of carbon and nitrogen sources. The extracellular fluid of PD630 exhibited the highest AFB1 degradation activity (81.67%), mainly due to the action of extracellular enzymes, with the extracellular enzyme precipitated by 70% saturated ammonium sulfate showing the highest degradation activity (55.01%). This extracellular enzyme maintained high degradation activity over a pH range (7–10) and broad temperature range (10–80 °C). Li+ and Cu2+ were identified as the primary activators of the enzyme, and the AFB1 lactone ring was cleaved and transformed into a substance completely different from the parent compound. In AFB1 contaminated corn, wheat, and peanut substrates, fermentation time, liquid-to-solid ratio, and inoculation amount all significantly impacted the degradation efficiency, with wheat showing the highest degradation efficiency. Additionally, PD630 showed a degradation rate of over 40% for the co-contaminant zearalenone.