一株乙腈降解菌的鉴定及其生物学特性

Identification and biological characterization of an acetonitrile degrading strain

【目的】明确乙腈降解菌BX2的分类地位及生物学特性,评价其处理含乙腈废水的可行性。【方法】通过形态特征、生理生化特性以及系统发育分析对菌株BX2进行鉴定。考察温度、初始pH及接种量等因素对菌株生长的影响,确定菌株的最佳生长条件及在该条件下的乙腈降解能力。测定菌株BX2对NaCl的耐受能力。【结果】乙腈降解菌BX2的形态特征及生理生化特性与紫红红球菌(Rhodococcus rhodochrous)最相近。其16S rRNA、gyrB、secA1基因序列与紫红红球菌的相似性分别为99.37%、99.29%、97.87%。最佳生长条件为35℃,初始pH 7.5,接种量1%。此条件下,菌株BX2在16 h内对浓度为800 mg/L乙腈的降解率为95.87%。菌株BX2在NaCl含量高于6%的培养基中无法生长。【结论】菌株BX2被鉴定为紫红红球菌。该菌株有较强的环境适应能力,可降解高浓度乙腈,在含氰废水的生物修复中有很好的应用前景。

[ Objective] To identify and characterize an acetonitrile degrading strain BX2, thus to assess its potentials in the treatment of acetonitrile containing wastewater. [ Methods ] By means of phenotype and physio-biochemical characterization as well as phylogenetic analysis, we identified strain BX2. The optimum culture conditions of the strain were studied with single factor test, and the degradation of acetonitrile under the optimal growth conditions was determined. Additionally, NaC1 tolerance was investigated. [ Results ] The phenotype and physio-biochemical characteristics of strain BX2 were similar to those of Rhodococcus sp.. The phylogenetic analysis based on 16S rRNA, gyrB and secA1 gene suggested strain BX2 was the closest relative of Rhodococcus rhodochrous with 99.37% , 99.29% and 97.87% sequence similarity respectively. The optimal conditions for cell growth were 35℃ , initial pH 7.5, and 1% inoculum. Under these conditions, the degradation rate of acetonitrile was 95.87% （800mg/L） within 16 h. Strain BX2 was able to grow in defined medium containing NaCl up to 6%. [ Conclusion] Strain BX2 was identified as Rhodococcus rhodochrous and named Rhodococcus rhodochrous BX2. It showed great environmental adaptation and high capability of degrading acetonitrile.