Kimura Hiroyuki, Sugihara Maki, Yamamoto Hiroyuki, Patel Bharat K C, Kato Kenji, Hanada Satoshi
Department of Biology and Geosciences, Faculty of Science, Shizuoka University, 836 Oya, Suruga, Shizuoka 422-8529, Japan.
Extremophiles. 2005 Oct;9(5):407-14. doi: 10.1007/s00792-005-0454-3. Epub 2005 Jun 25.
To investigate the biomass and phylogenetic diversity of the microbial community inhabiting the deep aquifer of the Great Artesian Basin (GAB), geothermal groundwater gushing out from the aquifer was sampled and analyzed. Microbial cells in the groundwater were stained with acridine orange and directly counted by epifluorescence microscopy. Microbial cells were present at a density of 10(8)-10(9) cells per liter of groundwater. Archaeal and bacterial small-subunit rRNA genes (rDNAs) were amplified by PCR with Archaea- and Bacteria-specific primer sets, and clone libraries were constructed separately. A total of 59 clones were analyzed in archaeal and bacterial 16S rDNA libraries, respectively. The archaeal 16S rDNA clones were divided into nine operated taxonomic units (OTUs) by restriction fragment length polymorphism. These OTUs were closely related to the methanogenic genera Methanospirillum and Methanosaeta, the heterotrophic genus Thermoplasma, or miscellaneous crenarchaeota group. More than one-half of the archaeal clones (59% of total 59 clones) were placed beside phylogenetic clusters of methanogens. The majority of the methanogen-related clones (83%) was closely related to a group of hydrogenotrophic methanogens (genus Methanospirillum). The bacterial OTUs branched into seven phylogenetic clusters related to hydrogen-oxidizing thermophiles in the genera Hydrogenobacter and Hydrogenophilus, a sulfate-reducing thermophile in the genus Thermodesulfovibrio, chemoheterotropic bacteria in the genera Thermus and Aquaspirillum, or the candidate division OP10. Clones closely related to the thermophilic hydrogen-oxidizers in the genera Hydrogenobacter and Hydrogenophilus were dominant in the bacterial clone library (37% of a total of 59 clones). The dominancy of hydrogen-users strongly suggested that H(2) plays an important role as a primary substrate in the microbial ecosystem of this deep geothermal aquifer.
为了研究大自流盆地（GAB）深层含水层中微生物群落的生物量和系统发育多样性，对从该含水层涌出的地热地下水进行了采样和分析。地下水中的微生物细胞用吖啶橙染色，并通过落射荧光显微镜直接计数。地下水中微生物细胞的密度为每升10⁸ - 10⁹个细胞。利用古菌和细菌特异性引物对，通过聚合酶链反应（PCR）扩增古菌和细菌的小亚基rRNA基因（rDNA），并分别构建克隆文库。古菌和细菌16S rDNA文库分别共分析了59个克隆。通过限制性片段长度多态性将古菌16S rDNA克隆分为9个操作分类单元（OTU）。这些OTU与产甲烷菌属的甲烷螺菌属和甲烷八叠球菌属、异养菌属嗜热栖热菌属或杂色泉古菌组密切相关。超过一半的古菌克隆（占59个克隆总数的59%）位于产甲烷菌的系统发育簇旁边。大多数与产甲烷菌相关的克隆（83%）与一组嗜氢产甲烷菌（甲烷螺菌属）密切相关。细菌OTU分为7个系统发育簇，分别与氢杆菌属和嗜氢菌属中的氢氧化嗜热菌、脱硫弧菌属中的硫酸盐还原嗜热菌、嗜热栖热菌属和水生螺菌属中的化学异养细菌或候选分类群OP10相关。与氢杆菌属和嗜氢菌属中的嗜热氢氧化菌密切相关的克隆在细菌克隆文库中占主导地位（占59个克隆总数的37%）。氢利用者的优势强烈表明H₂在这个深部地热含水层的微生物生态系统中作为主要底物发挥着重要作用。
