专一性脱硫菌脱硫活性比较与基因保守性研究

对几株能专一性脱除二苯并噻吩(DBT)中硫元素生成2-羟基联苯的细菌,即短芽孢杆菌(Bacillus brevis)R-6、德氏假单孢菌(Pseudomonas delafleldii)R-8、小球诺卡氏菌(Nocardia globerula)R-9、球形芽孢杆菌(Bacillus sphaericus)R-16、红平红球菌(Rhodococcus erythropolis)LSSE8-1和戈登氏菌(Gordonia nitida)LSSEJ-1展开研究。对照研究发现它们对DBT及其衍生物的代谢活性存在着一定的差异。为了从基因水平分析造成这些差别的原因,对这几株菌的脱硫基因展开了研究。根据Rhodococcus erythropolisIGTS8脱硫基因的保守区设计引物,PCR扩增了R-6、R-8的脱硫基因。测序结果表明脱硫基因高度保守,与IGTS8的相关脱硫基因相似性在99%以上。为了进一步验证不同专一性脱硫菌的脱硫基因的保守性,PCR扩增、克隆了LSSEJ-1和R-9的整个脱硫操纵子,结果表明脱硫基因在这两株菌中也是高度保守的。与IGTS8的相关脱硫基因相比较:R-9的dszA与IGTS8的dszA同源性为99.6%,LSSEJ-1的dszA与IGTS8的dszA的同源性为99.9%;R-9和LSSEJ-1的dszB的同源性与IGTS8的dszB都是99.9%;R-9的dszC与IGTS8的dszC同源性是99.9%,LSSEJ-1的dszC与IGTS8的dszC同源性为99.1%。对比研究认为专一性脱硫嗜温菌的脱硫基因的起源可能相同。

Comparison of the desulfurization activity among several bacteria and analysis of the conservation of their desulfurization genes

Several bacteria,Bacillus brevis R-6,Pseudomonas delafleldii R-8,Nocardia globerula R-9,Bacillus sphaericus R-16,Rhodococcus erythropolis LSSE8-1 and Gordonia nitida LSSEJ-1,which can convert dibenzothiophene into 2-hydroxybiphenyl and sulfate, were investigated. Desulfurization products were quantitively determined by HPLC. Result revealed that each of these bacteria desulfurize DBT at a different rate. In order to obtain more information, the fragments encoding desulfurizing enzymes were studied. Desulfurization genes of R-6 and R-8 were separately amplified via PCR with specific primers based on the related sequences of Rhodococcus sp.IGTS8.Both sequences areminimally 99% related to IGTS8 sequence. Afterwards, dsz operon of LSSEJ-1 and R-9 were amplified and cloned. Sequences are also highly conservative. Data shows that identity of dszA between R-9 and IGTS8 is 99.6%, and identity of dszA between LSSEJ-1 and IGTS8 is 99.9%;dszB sequence of R-9 and LSSEJ-1 is 99.6% similarity to their counterpart sequence from IGTS8;Identity of dszC between R-9 and IGTS8 is 99.9%,and identity of dszC between LSSEJ-1 and IGTS8 is 99.1%.It may be deduced that the origins of desulfurization genes from mesophilic bacteria are the same.