一株吡嘧磺隆降解菌S8-1的分离鉴定及生物学特性

Isolation, Identification and Biological Characteristics of a Pyrazosulfuron-ethyl Degrading Bacterium Strain S8-1

摘要:

以多年连续施用吡嘧磺隆除草剂的水稻试验田泥土为材料, 采用富集培养、平板反复划线分离方法, 分离到一株能以吡嘧磺隆为唯一碳源和能源生长的光合细菌(Photosynthetic Bacterium, 简称PSB), 命名为S8-1。通过菌落形态特征观察、菌体形态学观察、活细胞吸收光谱特征、培养特性、生理生化特性及16S rRNA同源性序列分析(GenBank登录号: GQ180069)等试验, 初步鉴定该菌为红假单胞菌属(Rhodopseudomonas sp.)。利用高效液相色谱(HPLC)测定了菌株S8-1的降解性能, 得出该菌降解吡嘧磺隆的最佳条件为: pH值为7.0?7.5, 温度为30°C?35°C; 在30°C与pH 7.0的光合细菌培养基中培养7 d, 对100 mg/L的吡嘧磺隆降解率为52.07%; 并且该菌对浓度高达800 mg/L的吡嘧磺隆仍保持降解活性, 外加发酵提取物能够明显提高菌体的生长及其降解效率, 显示了该菌在高浓度农药废水处理及土壤农药残留生物修复方面潜在的开发价值。

Abstract:

A strain of photosynthetic bacterium capable of degrading the herbicide pyrazosulfuron-ethyl, designated as S8-1, was isolated and purified from the rice experimental field soil samples which have been successively used pyrazosulfuron-ethyl for many years by continuous enrichment culture techniques. The isolate exhibited substantial growth in mineral salt medium amended with pyrazosulfuron-ethyl as a sole source of carbon and energy. Based on the colony and cell morphological observation, absorption spectra of living cells, cultural and biochemical characteristics, and the sequence analysis of the partial 16S rRNA gene, the isolate S8-1 had been preliminary identified as Rhodopseudomonas sp.. High performance liquid chromatography (HPLC) data analysis revealed the optimum degradation conditions of strain S8-1 were: pH value at 7.0?7.5 and temperature at 30°C?35°C, respectively. At the concentration of 100 mg/L, 52.07% of pyrazosulfuron-ethyl was degraded in 7 days at pH 7.0, 30°C and 7500 lx of light illumination intensity. The strain S8-1 still maintained degradation activity at the concentration of pyrazosulfuron-ethyl up to 800 mg/L, additional yeast extract can significantly increase the growth speed and degradation rate. The result indicated that strain S8-1 has potential value for biodegradation of pyrazosulfuron-ethyl plant waste water or contaminated soils and waters.