一株玉米赤霉烯酮降解菌的筛选及其降解特性

Screening and degradation characterization of a zearalenone-degrading strain

摘要:

玉米赤霉烯酮(zearalenone, ZEN)是一种由镰刀菌属真菌产生的次级代谢产物，严重危害人类和动物的健康。目的 筛选出可降解ZEN的细菌菌株，并探究其在不同条件下的生长与降解特性。方法 以ZEN为唯一碳源，从安徽某地连作的玉米田的土壤样品中筛选出一株能够高效降解ZEN的细菌菌株。通过形态学观察、生理生化试验和16S rRNA基因序列系统发育树分析对菌株进行鉴定；研究不同温度、pH值和培养时间对菌株生长速率和ZEN降解效率的影响；测定菌株不同活性成分对ZEN的降解效率，并对其活性物质进行定位。结果 从土壤样品中共筛选出21株ZEN降解菌候选菌株，其中菌株DC-R2的降解效果最佳。经形态学观察、生理生化检测和16S rRNA基因序列系统发育树分析，鉴定该菌株属于戈登氏菌属(Gordonia sp.)。该菌株的最适培养基为BHI培养基，最适ZEN降解温度和pH值分别为37 ℃和8.0。在此条件下，孵育6 h时可降解100%的ZEN (5 μg/mL)。活性成分定位试验结果表明，菌株DC-R2主要以胞内酶降解ZEN。结论 本研究报道了一株能够高效降解ZEN毒素的戈登氏菌DC-R2，该菌株所具有的胞内酶是降解ZEN的关键。本研究为后续工作中关键降解酶的纯化及其潜在应用奠定了坚实基础。

关键词:玉米赤霉烯酮;戈登氏菌;筛选;ZEN降解菌

Abstract:

Zearalenone (ZEN) is a secondary metabolite produced by the filamentous fungi of Fusarium, causing serious harm to human and animal health.Objective To identify a ZEN-degrading strain and investigate its growth and degradation characteristics under different conditions.Methods A bacterial strain that can efficiently degrade ZEN was screened out with ZEN as the only carbon source from soil samples of a field with continuous maize cropping in Anhui Province, China. The strain was identified by morphological observation, biochemical tests, and phylogenetic analysis based on 16S rRNA gene sequences. The effects of temperature, pH, and incubation time on the growth rate and ZEN degradation efficiency of the strain were studied. Furthermore, the efficiency of different active components of the strain on ZEN degradation was measured, and the locations of the active components were determined.Results A total of 21 ZEN-degrading strains were isolated from the soil samples, among which strain DC-R2 showed the strongest degradation effect and it was identified as Gordonia sp. BHI medium was the optimal medium for the growth of this strain. The optimal culture conditions of the strain for ZEN degradation were 37 ℃ and pH 8.0, under which 100% ZEN (5 μg/mL) was degraded within 6 h. Intracellular enzymes were the main contributors in DC-R2 to ZEN degradation.Conclusion We isolated a strain Gordonia sp. DC-R2 capable of efficiently degrading ZEN. The intracellular enzyme present in this strain is the key to the degradation of ZEN. This provides a foundation for the purification of the key degrading enzyme in subsequent work and the potential application.

Key words:zearalenone (ZEN);Gordonia;screening;ZEN-degrading strains