[Hydrocarbon-oxidizing microflora of uncontaminated seawater].

The distribution of hydrocarbon-oxidizing microflora in noncontaminated sea waters was studied in the northern region of the Pacific Ocean in the vicinity of the Copper Island. The total number of microorganisms was assayed as well as the number of heterotrophic, oligocarbophilic and hydrocarbon-oxidizing microorganisms. Oligocarbophilic bacteria were the most abundant group (from 120 to 24,000 cells per 1 ml), and predominated in 12 stations among 23. The number of heterotrophic organisms was not great and did not exceed 200 cells per 1 ml in 13 stations. A solid medium with an oil product (1%) which was used to determine the number of hydrocarbon-oxidizing bacteria gave overstated results due to the growth of oligocarbophilic forms that could survive in the presence of high hydrocarbon concentrations in the medium. A silica gel medium with an oil product is recommended. Despite the absence of oil contaminations in littoral waters, hydrocarbon-oxidizing bacteria were found in all samples and their content was high in some stations. This can be accounted for by the variety of nutrient requirements of these microorganisms and, apparently, by the presence in water of high molecular weight aliphatic lipids inding the capacity to oxidize hydrocarbons. Organisms belonging to the genera Mycobacterium and Arthrobacter prevailed among hydrocarbon-oxidizing bacteria.