厌氧原生动物的内共生甲烷菌及其氢酶的细胞化学研究

阿米巴鞭毛虫Psalteriomonas lanterna生活史分为鞭毛虫和阿米巴阶段。其培养液2%(V/V)氧时,细胞失去了内共生甲烷菌,继续培养在1%氧中,则鞭毛消失,小阿米巴出现。在1%氧条件下,阿米巴细胞生长较快,密度约1.2×104cells/ml,氧含量2.5%生长被抑制,超过7.5%细胞则死亡。无氧状态生长缓慢,加入甲酸甲烷杆菌(Methanobacterium formicicum Strain MsL)后,出现细胞密度增加的趋势。外萤光显微镜和电镜观察以及水洗P.lanterna后,培养液中生长的甲烷产物的事实证明;其细胞内含的萤光菌是甲烷杆菌(种类待定)。细胞化学染色法对细胞中氢酶的活性定位证实P.lanterna所含的类似微体的细胞器是氢体。染色结果:低浓度的戊二醛固定细胞,外加H2和苯异噻唑酞肼苯乙烯四唑(BspT)化合物,细胞的氢体膜周围有电子致密点生成。整个过程是在非常严格的厌氧条件下进行的。对照组以N2代替H2的细胞无上述反应。       

Oxygen responses of the free-living anaerobic amoeboflagellate Psalteriomonas lanterna

Abstract The effects of O₂ on growth of the anaerobic amoeboflagellate Psalteriomonas lanterna were studied. The organism tolerates low oxygen tensions (about 1% O₂ atm. sat.) and under these conditions growth was stimulated in mixed populations. Catalase could not be found in the cells, whereas superoxide dismutase was present. Addition of O₂ resulted in loss of the methanogenic endosymbionts and favoured the transformation to amoeba cells. Symbiont-free cells did not grow under anaerobic conditions probably due to the accumulation of H₂.     

变形鞭毛虫的细胞培养和内共生甲烷菌的变化

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。失去内共菌的鞭毛虫和变形虫细胞在厌氧中生长极为缓慢     

Monoxenic cultivation of the anaerobic amoeboflagellate Psalteriomonas lanterna and isolation of the methanogenic endosymbiont

Abstract The endosymbiont of the anaerobic amoeboflagellate Psalteriomonas lanterna was isolated and identified as Methanobacterium formicicum , a H₂/CO₂- and formate-utilizing methanogen. A monoxenic culture of P. lanterna was established in a complex liquid medium with Pseudomonas fluorescenss as food bacterium.