玉米赤霉烯酮降解菌的鉴定及其降解特性

Identification and degradation characteristics of a zearalenone degrading bacterium

摘要:

【背景】玉米赤霉烯酮(Zearalenone，ZEN)是一种具有类雌激素作用的霉菌毒素，常会污染谷物和饲料，严重威胁动物和人类的健康。生物脱毒作为理想的去除ZEN的方法，广受关注，然而相关菌株较少，仍有待进一步筛选。【目的】明确一株玉米赤霉烯酮降解菌的生物学分类地位，并优化其赤霉烯酮降解菌降解条件。【方法】通过菌株的16S rRNA基因序列比对，构建系统发育进化树，并开展了相关培养条件的单因素优化和玉米赤霉烯酮降解动力曲线的绘制。【结果】实验菌株WLB-29经鉴定为斯塔普氏菌属(Stappia)，其16S rRNA基因序列在GenBank上登录号为MT196321，该序列与模式菌株Stappia indica B106T相似性最高为97.47%，初步确定为斯塔普氏菌属潜在新种。单因素优化表明，菌株降解玉米赤霉烯酮的最佳条件为LB培养基、37 °C培养、pH 8.0、2%接种量和玉米赤霉烯酮初始浓度为10 mg/L，在此条件下培养144 h后，玉米赤霉烯酮的降解率最高可达92.56%。【结论】菌株WLB-29具有较好的ZEN降解作用，为进一步解析菌株降解ZEN作用机理提供了研究基础，也为进一步开发利用菌株开展ZEN的生物脱毒提供了新的菌株资源。

Abstract:

[Background] Zealenone (ZEN) is a mycotoxin with estrogen-like effect, which often contaminates grains and feed, and threatens the health of animals and humans seriously. As an ideal method to remove ZEN, the biological detoxification has been received with wide attentions. However, there are few related degradation strains, which need to be further screened. [Objective] To clarify the biological classification status of a ZEN-degrading bacterium and optimize the degradation conditions. [Methods] The phylogenetic tree was constructed by 16S rRNA gene sequences. Optimization of culture conditions with single factor analysis was carried out, and degradation kinetic of ZEN was analyzed. [Results] Based on 16S rRNA gene sequence similarities, the closest relative of WLB-29 was Stappia indica B106T (97.47%), which suggested WLB-29 was a potential novel species of the genus Stappia (GenBank accession number MT196321). Results of the optimization showed that the best conditions for strains to degrade ZEN were followed: LB culture medium, 37 °C, pH 8.0, 2% inoculum and initial concentration of 10 mg/L ZEN. Under the conditions, the degradation rate could reach 92.56% after cultured 144 hours. [Conclusion] The strain WLB-29 could degrade ZEN. It provides a research basis for further analyzing the mechanism of ZEN degradation by the strain, and utilization of the strain to ZEN detoxification in future.