变形鞭毛虫的细胞培养和内共生甲烷菌的变化

CULTIVATION OF AMOEBOFLAGELLATE, PSALTERIOMONAS LATERNA, AND CHANGES OF THE ENDOSYMBIONTS, METHANOGENIC BACTERIA

一种奇特的变形鞭毛虫（Ｐｓａｌｔｅｒｉｏｍｏｎａｓ ｌａｍｅｒｎａ）从淡水厌氧污泥中分离后，在室内培养成功。其生长适宜条件：ｐＨ６·８，温度１５－２５℃，培养瓶内氧含量ｌ％或少于２·５％，盐含量不超过０．ｌｍｍｏｌ／Ｌ，所需营养物质０．０２％（Ｗ／Ｖ）的 蛋白胨。在无氧条件下生活的细胞产生甲烷。荧光显微镜和电镜揭示在寄主细胞内有内共生的甲烷菌。这些甲烷菌和类似微体的细胞器紧密相连形成球体。带有内共生菌的Ｐ．ｌａｎｔｅｒｎａ＋在厌氧环境中生活较好。当加入１％或少于２·５％氧时·其内共菌消失并转变成无甲烷菌的Ｐ．ｌａｎｔｅｒｎａ－，继续在相似的含氧量下培养时，其鞭毛消失，转变成变形虫。变形虫阶段的细胞仍不含内共生菌。

A novel amoeboflagellate Psalteriomonas lanterna has been isolated from freshwater anaerobic sediment, and cultured in monoculture. Optimal conditions for growth were: pH7, 15- 25 ℃, and 1 % or less than 2. 5 % of oxygen in the headspace of the culture bottle. The concentration of salts and sulfite were less than 0 lmg/L. Anaerobic cultivation of P. lanterna produced methane. Epifuorescence light and electron microscopic observations revealed the presence of methanogenic bacteria as endosymbionts. These methanogens in protozoa cells were found to be closely associated with microbody-like organelles and formed a central body. P. lanterna+ (with endosymbionts) grew well in anaerobic culture. When P. lanterna+ were cultivated in culture medium containing 1 % or less than 2. 5% of oxygen, they lost their endosymbionts and changed into. P. Lanterna-. When the cells were cultured continually in medium with the same content of oxygen, the flagellate of the cells disappeared, and small amoebae appeared. Cells of the amoeboid stage lacked the methanogenic endosymbionts. Both of the flagellate and amoebae cells without endosymbionts grew poorly in anaerobic culture.