一株烃降解菌的分离鉴定及耐盐机制

Isolation,Identification and Salinity Tolerance of A Novel Hydrocarbon-degrading Strain,Rhodococcus sp. HX-2

随着科学技术与工业经济的发展,石油的开采量也在逐年提升,在其开采以及加工处理过程中会产生大量含有较高盐分的含油废水难以处理,因此对高耐盐度烃类降解菌的筛选极为重要。从新疆油田石油污染土壤中分离得到一株以柴油为唯一碳源的耐盐菌株HX-2,通过生理生化特征、菌体形态观察及16S rRNA基因序列分析,鉴定菌株HX-2属于红球菌属(Rhodococcus),该菌株可耐受的最高盐度(Na Cl)和柴油浓度分别为10%和8 000 mg/L。菌株生长及降解的最适p H和温度分别为7. 0和25℃,在盐度为5%以内、p H为7. 0、温度为25℃、菌种投加量为2%的条件下,初始浓度为4 000 mg/L的柴油经4 d降解后,去除率均超过50%以上,且盐度为10%仍有10. 3%的降解率。对其耐盐机制进行分析表明细胞内相容性物质(甜菜碱)的含量随着盐浓度的增加而增大,说明甜菜碱的积累是菌株抵抗高盐浓度的主要机制。通过外源添加甜菜碱可以改善菌株在高盐条件下的生长情况并提高柴油降解率。因此,菌株HX-2是一株在盐渍化烃类污染修复方面极具应用潜力的烃降解菌。

With the development of the world economy and industry,the use of petroleum is constantly increasing. The oily wastewater generated during oil exploitation and petroleum processing often contains high concentrations of salt,which makes it difficult to processing. Therefore,screening high salinity tolerance of hydrocarbon-degrading bacteria is extremely important. A salt-tolerant diesel-degrading bacterium HX-2,which could utilize diesel as sole carbon source,was isolated from oil contaminated soil in Xinjiang Oil Field. On the basis of morphology,biochemical and physiological characteristics and 16 S rRNA sequence analysis. Strain HX-2 was identified as Rhodococcus sp. Strain HX-2 could tolerate 10% of NaCl and 8 000 mg/L of diesel. The suitable pH and temperature for strain HX-2 growth is 7 and 25 ℃,respectively. Under the conditions of salinity less of 5%,p H of 7. 0,temperature of 25 ℃,the degradation rate of diesel was over 50% when initial concentration of 4 000 mg/L,and the degradation rate was still 10. 3% when NaCl was 10%. The content of intracellular compatible solute( betaine)increased with the salt concentration,indicating that the accumulation of betaine is the main mechanism by which HX-2 resists high salt concentration. Exogenous betaine addition improved cell growth and the degradation rate of diesel oil in the presence of high salinity. These results demonstrate the capability of Rhodococcus sp. HX-2 to degrade hydrocarbons and its potential for application in bioremediation of hydrocarbon pollution in saline environments.