Ecological and Physiological Studies on Marine Methane-Oxidizing Bacteria.

Research Project

Project/Area Number	62560184
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	General fisheries
Research Institution	Ocean Research Institute, University of Tokyo
Principal Investigator	OHWADA Kouichi Ocean Research Institute, University of Tokyo, 海洋研究所, 助教授 (30013585)
Project Period (FY)	1987 – 1988
Project Status	Completed (Fiscal Year 1988)
Budget Amount *help	¥2,100,000 (Direct Cost: ¥2,100,000) Fiscal Year 1988: ¥500,000 (Direct Cost: ¥500,000) Fiscal Year 1987: ¥1,600,000 (Direct Cost: ¥1,600,000)
Keywords	Methane / Methane oxidizing bacteria / 海洋細菌
Research Abstract	Methane is utilized biologically by limited groups of microorganisms called "methanotroph". These groups are composed of some limited spe-cies of yeasts and bacteria. There has been rather a lot of works on methanotrophs in freshwater areas and fermentasion aspects. There has been not so many works on marine methane oxidizing bacteria in spite of the methane gas distribution not only in the eutrophicated coastal sediments but also recently found areas of hot thermal venting and cold seep. We tried to culture marine groups of methanotroph using basal medium of noaddition of organic matter, and addition of methane + air (1:1) as air phase. After incubation of coastal sediment in the medium for one month, a portion was transferred to fresh medium. Such culture was repeated 3 to 4 times. Microorganisms in the medium was studied for the ability to utilize methane using resting cells with basal medium, methane and air. It was confirmed that these cells utilized mthane and oxygen and produced carbon dioxide with the progress of time. This method was used to check the distribution of methane oxidizing bacteria in coastal areas, such as Otsuchi bay, Aburatsubo Inlet and Tokyo Bay, and in off shore area like cold seep area of Sagami Bay. Isolation of these bacteria as pure culture was not successflu at present time because of the dificulty of colony formation on agar plates. Electron microscopicobservation with thin section of such microorganisms revealed the presence of II types of membrane structure which is charecteristics of methanotrophs. Distribution of methane in the core waters of sediments and in the water columns was also studied in the coastal areas.