在辽河口湿地油田石油污染土壤中分离到一株耐盐柴油高效降解菌株L7,经过形态学观察、16S rRNA基因序列分析鉴定菌株L7属于不动杆菌属(Acinetobacter).该菌株能够以柴油、十五烷、十六烷、十七烷、十八烷、十九烷、二十烷和二十二烷为唯一碳源和能源生长.在柴油无机盐培养基中,菌株的最适生长温度为30°C,最适pH值为7.0,菌株L7在pH 6.0~9.0,盐度范围为3%以内都可以生长.与其他的菌株相比较,菌株L7在柴油中生长更加迅速,在最适培养条件下培养4d后菌株的OD600nm就可以达到4.0,通过紫外分光光度法测定培养5d后,柴油的降解效率为61.5%.通过对菌株L7的全基因组测序和分析,在基因组上找到一个烷烃羟化酶基因alkB,将基因克隆到pME6032质粒上,并电转至不依赖柴油生长的恶臭假单胞菌KT2440中,含有该质粒的KT2440菌株能够在柴油无机盐培养基中生长.GC-MS检测确定了菌株L7及其alkB基因对饱和烷烃的降解能力.推测菌株L7中烷烃降解途径为末端氧化途径,是由烷烃羟化酶催化反应生成相应的醇,最终通过β-氧化反应实现完全矿化.%A high-efficient diesel degrading bacterial strain isolated from oil-contaminated soil in Liaohe oil field was identified as Acinetobacter sp. and named as L7. The strain could efficiently grow with diesel, n-tridecane, n-hexadecane, n-heptadecane, n-octadecane and n-nonadecane as its sole carbon and energy source. The cultivation conditions of the strain L7 in diesel basic salt medium were investigated. The suitable pH value for the growth of the strain ranged from 6.0~9.0 with the optimum value of 7.0. The optimum temperature and salinity for the cultivation of the strain was 30°C and 1%, respectively. The degradation efficiency of diesel oil was 61.5% under the optimum conditions. Based on the whole-genome DNA sequence analysis of the bacterial strain, an alkane hydroxylase gene, alkB, was identified. To study the function of the alkB gene in n-alkane utilization by the bacterial strain, the pME6032-alkB plasmid was constructed and electroporated into another bacterial strain Pseudomonas KT2440, which could not grow in diesel. The electroporated bacteria Pseudomonas KT2440 could grow in diesel basic salt medium. Through gas chromatography-mass spectrometric analysis, the degradation capacity of the bacterial strain L7 for n-alkanes and the roles of the alkB gene were determined. The results indicated that the n-alkanes were degraded by the strain L7 via the terminal oxidation and β-oxidation pathway.
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