Ecological and Physiological Studies on Marine Methane-Oxidizing Bacteria.

甲烷是由有限的微生物群生物利用的，这些微生物被称为“甲烷菌”。这些菌群由一些有限的酵母菌和细菌组成。在淡水区和发酵方面，已经有相当多的关于甲烷氧化菌的工作。尽管甲烷气体不仅分布在富营养化的海岸沉积物中，而且最近还发现了热喷口和冷渗漏区，但对海洋甲烷氧化菌的研究还很少。在不添加有机物的基础上，以甲烷+空气(1：1)为气相，对海洋产甲烷菌群进行了培养。将沿海沉积物在培养基中培养1个月后，将一部分转移到新鲜的培养基中。这样的培养重复3~4次。研究了基础培养基休眠细胞、甲烷和空气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。用该方法检测了大津湾、厦门湾、东京湾等近岸海域以及相模湾冷渗区等近海海域甲烷氧化菌的分布情况。由于琼脂平板集落形成困难，目前以纯培养的方法分离这些细菌并不成功。用电子显微镜对这些微生物的薄片进行了观察，发现存在II型膜结构，这是甲烷氧化菌的特征。还研究了甲烷在沿海地区沉积物核心水和水柱中的分布。

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.