Studies on degradation mechanism of petroleum under anoxic condition.

从油田中分离出的菌株HD-1能够厌氧降解脂肪族和芳烃。本课题研究了细菌在缺氧条件下降解石油的机理，以十四烷（烷烃）为底物，在HD-1细胞中积累了两种烷烃作为降解中间体。最后通过FT-IR、1H-NMR、GC/MS等分析数据，鉴定出该烯烃的主要成分为1-十二烯。结果表明，菌株HD-1在缺氧条件下对烷烃进行脱氢。虽然1992年德国的一个研究小组报道了一个在缺氧条件下烷烃降解的例子，但这是第一个关于降解中间体结构分析的报告。此外，发现菌株HD-1能够以CO2为唯一碳源生长，并在细胞内产生烷烃。其产量为干电池质量的0.1%。从二氧化碳到烷烃的代谢途径需要在未来进一步阐明。最近从油罐中分离出一株新的细菌TK-122。在缺氧和缺氧条件下，其原油降解能力均优于HD-1。石油中约70%的烷烃（从辛烷到十六烷）在缺氧条件下3天内降解。以钼酸盐（MoO4^<2->）为电子受体，对烷烃进行厌氧降解。这一结果表明发现了一条新的石油降解途径。根据菌株TK-122的16S rRNA核苷酸序列分析，大肠杆菌属或柠檬酸杆菌属是最可能的属。然而，该菌株的生理特征与这些属都不匹配。结果表明，菌株TK-122属于一个新属。

Bacterial strain HD-1, isolated from an oil field, is able to degrade both aliphatic and aromatic hydrocarbons anaerobically. In this project, bacterial degradation mechanisms of petroleum under anoxic condition was studied Utilizing tetradecane (alkane) as a substrate, two kinds of alkene were accumulated as degradation intermediates in HD-1 cells. Finally a main component of the alkenes was identified as 1-dodecene based on analyzes data from FT-IR,1H-NMR,and GC/MS.This result shows that alkane is dehydrogenated by the strain HD-1 under anoxic condition. Although one example was reported in 1992 from a research group in Germany about alkane degradation under anoxic condition, this is the first report on the structural analysis of a degradation intermediate. Moreover, strain HD-1 were found to be able to grow on CO2 as a sole carbon source and produce alkane in the cells. Its production yield was 0.1% in dry cell weight. The metabolic pathway from CO2 to alkane needs to be elucidated in a future.Recently, a new bacterial strain TK-122 was isolated oil-reservoir tank. Its oil degradation ability is superior to HD-1 under both oxic and anoxic conditions. About 70% of alkanes (from octane to hexadecane) in petroleum, was degraded in 3 days under anoxic condition. Molibdenate (MoO4^<2->) was used as an electron acceptor in the anaerobic degradation of alkane. This result indicates a finding of a new petroleum degradation pathway. According to the analysis on 16S rRNA nucleotide sequence of the strain TK-122, Escherichia or Citrobacter was most probable genus. However, physiological characterization of the strain matched with none of these genera. It is indicated that the strain TK-122 belongs to a new genus.