一株红霉素降解菌的筛选、鉴定与降解特性

优良的菌种资源是污染环境微生物修复技术的核心。为获取红霉素高效降解菌,采用梯度驯化法,以长期堆放鸡粪的有机肥生产车间土壤为对象,开展降解菌筛选鉴定,并研究不同红霉素质量浓度、培养温度、转速、初始pH值,以及外加碳氮源、金属离子对菌株降解红霉素的影响。结果表明,筛选获得一株红霉素高效降解菌株Ery-6。通过菌落形态和16S rDNA序列分析方法,将该菌株鉴定为甲基菌属(Methylobacillus sp.)。Ery-6菌株可以在以红霉素为唯一碳源的无机盐培养基中快速生长,60 h后进入生长稳定期。接种Ery-6菌株可提高红霉素在培养基中的降解速率常数,使其半衰期从88.4 h降低至30.7 h。该菌株在含有100 mg·L^-1红霉素的无机盐培养基中,在温度35 ℃、转速120 r·min^-1、初始pH值7.0、外加50 mg·L^-1蔗糖的条件下,对红霉素的降解效果最佳,48 h降解率达88.68%。菌株可耐受1 000 mg·L^-1高质量浓度的红霉素,在温度35 ℃、转速120 r·min^-1、初始pH值7.0的条件下48 h降解率达31.95%。该菌株对多种金属离子具有良好的耐受性;但Cu²⁺既会抑制Ery-6菌株的生长,也会对其降解红霉素产生一定的影响。本研究首次发现甲基菌属菌株具有降解红霉素的能力,且降解效果较好,为生物降解养殖废弃物与环境中的抗生素污染提供了一种新的微生物资源。

Isolation and identification of an erythromycin degradation bacterium strain and its biodegradation characteristics

In order to obtain efficient erythromycin degradation bacteria, erythromycin was used as the sole carbon source, and gradient domestication method was used to isolate and screen erythromycin degradation bacteria. It was shown that an erythromycin degradation bacterium strain Ery-6 was isolated from the soil of an organic fertilizer production workshop where chicken manure was stacked for a long time. The Ery-6 strain was identified as Methylobacillus sp. through colony morphology identification and 16S rDNA sequence analysis. Further, high performance liquid chromatography (HPLC) was used to measure the degradation rate of erythromycin, and the degradation conditions of erythromycin by Ery-6 strain were optimized, including different erythromycin concentration, culture temperature, rotation speed, initial pH value, exogenous carbon and nitrogen sources and metal ions. The Ery-6 strain could reach a degradation rate of 88.68% after 48 h in inorganic salt medium containing 100 mg·L^-1 erythromycin under temperature of 35 ℃, rotation speed of 120 r·min^-1, initial pH value of 7.0, and 50 mg·L^-1 sucrose. Meanwhile, the Ery-6 strain could tolerate 1 000 mg·L^-1 high-concentration erythromycin, and exhibited a degradation rate of 31.95% after 48 h under temperature of 35 ℃, rotation speed of 120 r·min^-1, initial pH value of 7.0. The Ery-6 strain had a good tolerance to various metal ions. Cu²⁺ could inhibit its growth, and pose direct effect on the degradation of erythromycin by Ery-6. The present study for the first time reported that the Methylobacillus sp. strain had the ability to degrade erythromycin, and it could tolerate high concentration of erythromycin, and maintain a certain degradation rate, which provided new microorganism for biodegradation of erythromycin in the environment.