一株高效柴油降解菌Serratia sp. J-3的筛选、鉴定和降解特性

Isolation and identification of a high efficiency diesel oil degrading strain Serratia sp. J-3 and its degradation characteristics

[目的]本文旨在筛选出不同种类和特性的高效降解柴油菌株,研究降解菌株对不同环境下柴油污染的降解机制。[方法]从南京扬子石化厂区的油泥沉积物中分离出1株高效柴油降解菌J-3,通过细菌形态学、生理生化及16S rRNA基因序列分析比对初步鉴定菌株J-3为沙雷氏菌属(Serratia sp.)。通过水培及土壤培养并结合气质联用(GC-MS)和全基因组比对技术研究其降解率和降解机制。[结果]该菌能利用柴油为唯一碳源生长,产生表面活性物质,具有稳定的乳化性能。在温度20~40℃、初始pH5~9条件下生长良好,能耐受15 g·L^-1 NaCl和5 g·L^-1柴油。在最适生长条件(pH7,25℃,1 g·L^-1 NaCl,0.5 g·L^-1柴油)下对柴油降解率为62.0%,GC-MS图谱分析确定菌株J-3对柴油中各组分均有降解能力,对部分中长直链烷烃降解率超过99%。通过菌株J-3的全基因组比对分析,发现2个烷烃氧化相关的基因,烷烃羟化酶基因alkB和长链烷烃羟化酶基因almA,推断菌株J-3能降解柴油可能是这2个氧化酶基因产生作用。将菌株J-3应用于柴油污染土壤修复试验,对土壤中各柴油组分均有降解能力。不同处理下菌株J-3降解率可达33.8%~49.0%,可有效降解土壤中的柴油。[结论]Serratia sp. J-3是一株高效降解柴油的菌株,在水体和土壤中均能很好利用柴油进行生长代谢,可应用于柴油污染实际生物修复工程。

[Objectives]The paper aimed to screen different kinds and properties of diesel strains with high degradation capacity and study their degrading mechanism in different environmental media. [Methods]A high-efficiency diesel degrading bacteria named as strain J-3 was isolated from the sludge sediments of Nanjing Yangzi Petrochemical Plant. The physiological and biochemical test together with 16 S rRNA gene sequencing analysis indicated that the strain J-3 belonged to Serratia sp.. The degradation efficiency of diesel and the degradation mechanism were studied by hydroponic and soil culture methods combined with gas chromatography-mass spectrometric analysis(GC-MS)and genome comparison techniques. [Results]The strain could efficiently grow using diesel as its sole carbon and energy source. It could produce surfactant,which showed it had a stable emulsifying property. The strain grew well under the temperature of 20-40 ℃,and the pH of 5-9 conditions,it could tolerate 15 g·L^-1 salinity and 5 g·L^-1 diesel concentration. The degradation efficiency of diesel under the optimal growth conditions(pH7,25 ℃,1 g·L^-1 salinity and 0.5 g·L^-1 diesel concentration)was 62.0%. GC-MS spectrum analysis confirmed that J-3 had the ability to degrade all components in diesel oil,and the degradation of some media and long straight-chain alkanes exceeded 99%. Based on the whole-genome DNA sequence analysis of the strain J-3,the two genes associated with alkane oxidation were found,namely alkB,an alkane hydroxylase gene,and almA,a long-chain alkane monooxygenase gene. These two oxidase genes might play a role in the degradation of diesel oil by strain J-3. In addition,when the strain J-3 was applied to the soil remediation test of diesel pollution,it could degrade all diesel components in the soil. The degradation of strain J-3 under different treatments was up to 33.8%-49.0%,which could effectively degrade diesel in soil. [Conclusions]The strain J-3 was a high-efficiency diesel degradation bacterial strain. It can be well used for growth in both water and soil,and can be applied to the actual bioremediation project of diesel oil pollution.