Ecological and Physiological Studies on Marine Methane-Oxidizing Bacteria.

甲烷被称为“甲烷营养菌”的有限微生物群体生物利用。这些菌群由一些有限的酵母菌和细菌组成。关于淡水地区甲烷氧化菌和发酵方面的研究已经相当多。海洋甲烷氧化细菌不仅在富营养化的海岸沉积物中有甲烷气体分布，而且在最近发现的热液喷口和冷泉区也有甲烷气体分布，但对海洋甲烷氧化细菌的研究还不多。在不添加有机物的基础培养基上，以甲烷+空气（1：1）为空气相，培养海洋甲烷氧化菌。沿海沉积物在培养基中孵育一个月后，将一部分转移到新鲜培养基中。将这种培养重复3至4次。使用具有基础培养基、甲烷和空气的静息细胞研究培养基中的微生物利用甲烷的能力。证实了这些细胞利用甲烷和氧气，并随着时间的推移产生二氧化碳。利用该方法对大槌湾、油坪湾、东京湾等沿岸地区和相模湾冷泉区等近海海岸地区的甲烷氧化细菌分布进行了调查。由于在琼脂平板上形成菌落的困难，目前这些细菌作为纯培养物的分离尚不成功。电镜观察表明，该菌具有甲烷氧化菌特有的Ⅱ型膜结构。还研究了沿海地区沉积物核心沃茨和水柱中甲烷的分布。

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.