THERMOPHILIC HYDROCARBON-OXIDIZING BACTERIA FROM OIL STRATA

Two strains of thermophilic hydrocarbon-oxidizing bacteria were isolat ed from Kazakhstan and West Siberia oil fields with stratal temperatur e above 50 - 60 degrees C. The bacteria were motile endospore-forming rods. Vegetative cells of strains B and K had ultrastructure typical o f Gram-positive bacteria and showed Gram-positive staining. The bacter ia did not show pigmentation. They developed at temperatures from 40 u p to 70 degrees C, with the optimum at 55 - 60 degrees C. The best gro wth was observed at neutral pH and NaCl concentrations of about 5 - 10 g/liter. Both strains were obligately aerobic and developed on synthe tic media with a wide range of organic substrates, including n-alkanes . No growth factors were required. Ammonium, nitrate, and dinitrogen w ere equally favorable as the nitrogen source. The G + C content in the DNA of strains K and B was 56.7 and 56.9 mol. %, respectively. On the basis of their morphological, physiological, and biochemical features the strains were assigned to Bacillus thermoleovorans. The investigat ed thermophilic hydrocarbon-oxidizing bacteria from oil strata had a n umber of ecologically beneficial features demonstrating their adaptati on to the habitat.