ISOLATION OF A NEW MIXOTROPHIC BACTERIUM WHICH CAN FIX CO2 AND ASSIMILATE ALIPHATIC AND AROMATIC-HYDROCARBONS ANAEROBICALLY

We isolated a new type of Gram-negative mixotrophic bacterium, Pseudomonas sp. HD-1, which is a facultative anaerobe. Cells were grown on CO2 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 vacuoles 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-layer structure irrespective of the presence of oil.