Characterization of Anaerobic Petroleum Degrading Bacterium strain HD-1.

我们分离到一株新型革兰氏阴性混合营养细菌--假单胞菌。HD-1，为兼性厌氧菌。以CO2为唯一碳源，H_2为唯一碳源，通过添加脂肪族和芳香族碳氢化合物促进了该菌株的厌氧生长。当细胞在正构烷烃上厌氧生长时，细胞内形成许多油空泡，细胞干重的40-50%是脂肪和油。细胞内亲水性成分的增加表明脂肪烃的厌氧同化作用。结果表明，该菌株在厌氧条件下能降解十四烷(C&lt；14&gt；)，其主要代谢中间产物之一为1-十二烯(C&lt；12&gt；)。这一结果表明，烷烃在没有分子氧的情况下可以通过不同于β-氧化的途径进行生物降解。发现该菌株在CO_2上生长，有十四烷存在，无H_2气体和光照。这些事实有力地表明，该细菌能够以厌氧方式利用烷烃作为能源。

We isolated a new type of Gram-negative mixotrophic bacterium, Pseudomonas sp. HD-1, which is a facultative anaerobe. Cells were grown on CO_2 as a sole carbon source in the presence of H_2. Anaerobic growth of the strain was enhanced by the addition of aliphatic as well as aromatic hydrocarbons. When cells were grown on n-alkane anaerobically, many oil vacuoes formed in the cells and about 40-50% of the dry cell weight was lipid and oil. The total increase in the hydrophilic components of the cells indicated the anaerobic assimilation of aliphatic hydrocarbon. Electron microscopic observation showed that the cell surface was highly wavy and that the membrane had a multi-layr structure irrespective of the presence of oil.The strain was demonstrated to degrade tetradecane (C_<14>) under anaerobic condition and one of the major metabolic intermediates was identified as 1-dodecene (C_<12>). This result demonstrates that alkanes are biodegradable without molecular oxygen via a pathway different from beta-oxidation. The strain was found to grow on CO_2 in the presence of tetradecane and absence of H_2 gas and light. These facts strongly indicate that the bacterium is able to utilize alkane as an energy source anaerobically.