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

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.

Key words:Pyrazosulfuron-ethyl, Enrichment culture technique, Photosynthetic bacterium, Rhodopseudomonas sp.