该实验采用富集培养的方法从土壤中筛选出有效降解玉米赤霉烯酮（Zearalenone，ZEN）的菌株。初筛采用ZEN涂布至无机盐培养基作为唯一碳源，复筛是以菌株的发酵液对ZEN的降解率作为评价指标，得到一株菌株A.lwoffi.Haut.1，其发酵液在37 ℃下与5 μg/mL ZEN共培养48 h，降解率高达93.54%。经16S rDNA基因测序分析、生理生化实验和菌落形态观察初步对菌株进行鉴定，并对该菌株的降解活性物质进行初步定位，最终探究丹宁-聚乙二醇法和盐沉法对无细胞上清液进行粗降解酶的提取效果。结果表明，该菌株鉴定判断为鲁氏不动杆菌（Acinetobacter lwoffii）；该菌株的无细胞上清液的降解率最高为82.31%，无细胞上清液经加热处理、蛋白酶K处理和蛋白酶K+SDS处理后，降解率分别为20.10%、41.67%和18.68%，说明降解活性物质主要为胞外酶；当单宁浓度为15 mg/mL，聚乙二醇溶液浓度为10 mg/mL，提出的酶液降解率为64.33%，而盐沉法加入60%硫酸铵提出的粗酶液降解率为20.30%，因此，单宁聚乙二醇法提取降解酶效果更好。该研究为菌株降解ZEN的作用机理提供了研究基础，也为生物降解ZEN提供了新的研究材料。

A zearalenone (ZEN)-degrading bacterial strain was screened from soil using the enrichment culture method. ZEN was coated onto an inorganic salt medium as the sole carbon source in the initial screening, and the degradation rate of ZEN in the fermentation broth of the strain was used as the evaluation index in the second screening. The strain with the highest degradation rate was named A.lwoffi.Haut.1, which showed a degradation rate of 93.54% after co-incubation with 5 μg/mL ZEN in the fermentation broth for 48 h at 37 ℃. The strain was identified through 16S rDNA gene sequencing analysis, physiological and biochemical experiments, and observation of colony morphology, followed by the preliminary localization of its degradation active substances. Finally, the effectiveness of the tannic acid-polyethylene glycol and salt precipitation methods for crude ZEN-degrading enzyme extraction in cell-free supernatant was tested. A.lwoffi.Haut.1 was identified as a strain of Acinetobacter lwoffii. The highest ZEN-degradation rate of A.lwoffi.Haut.1 in cell-free supernatant was 82.31%, which decreased to 20.10%, 41.67%, and 18.68% after treatment with heat, protease K, and protease K+SDS, respectively, thus indicating that extracellular enzymes were the main degradation active substances. The degradation rate of the crude enzyme solution extracted using 15 mg/mL of tannic acid and 10 mg/mL of polyethylene glycol solution was 64.33%, and that using salt precipitation with 60% ammonium sulfate was only 20.30%. Therefore, the tannic acid-polyethylene glycol method was highly effective for the extraction of degradation enzymes. This study provides a research basis for investigating the bacterial degradation mechanism of ZEN and a new research material for ZEN biodegradation.

河南省高校科技创新团队项目（20IRTSTHN023）；郑州市重大科技创新专项项目（2020CXZX0077）