Characteristics and Mechanism of Zearalenone Degradation by Acinetobacter pittii

Zearalenone (ZEN) is one of the most widely distributed Fusarium toxins that can contaminate a variety of agricultural products, such as maize. A strain with high degradation efficiency of ZEN was isolated from wheat inter-root humus soil with ZEN as the sole carbon source. Through morphological observation, 16S rDNA sequencing and whole genome sequencing, it was identified as Acinetobacter pittii M - 1. Through degradation activity verification, it was found that the detoxifying enzymes with degradation activity to ZEN were mainly concentrated in the fermentation supernatant. It was found that the optimal degradation temperature and pH for M - 1 were 60 ℃ and 9, respectively. Under these conditions, the degradation rate for 10 μg/mL of ZEN reached as high as 90.85% within 48 h. Mn²⁺ could significantly enhance the detoxification activity of the fermentation supernatant. Under the optimal conditions, M - 1 achieved a degradation of 89.92% for 2 μg/mL of ZEN. Based on the Q exactive focus quadrupole orbitrap mass spectrometry, the structure identification of ZEN degradation products was preliminarily completed, and the ZEN degradation product was identified as zearalenone 4-sulfate, which had significantly lower toxicity than ZEN. Based on the M - 1 whole genome sequence, screening of genes encoding ZEN detoxification enzyme was carried out, and the coding gene in M - 1 was preliminarily identified as ahpC, and the detoxification enzyme was NADH-dependent peroxiredoxin. In addition, it was found that H₂O₂ intervention could significantly improve the degradation efficiency of ZEN in M - 1, and further increased the possibility of detoxification enzyme as NADH-dependent peroxiredoxin. This research indicated the ability of Acinetobacter pittii to degrade ZEN, which provided novel microbial resources for ZEN detoxification in grains. Furthermore, it established a foundational framework for high-efficiency expression and industrial application of ZEN-detoxifying enzymes derived from Acinetobacter pittii.