Thermal tolerance of prokaryote on surface of substrates

限制极端生物栖息深度的最关键参数之一是温度。已知超嗜热菌的最高生长温度为121摄氏度，但一些微生物生活在超过300摄氏度的底物表面，如热液烟囱。因此，我们推测那些附着在固体表面的人可能对高温等极端环境具有耐受性。我们使用耐300℃高温的井下流体采样器对这一假设进行了现场采样。这种钻孔采样器使我们能够将地热流体就地采集到压力密闭的样本室(1250毫升)，而不会发生剧烈的压力变化。此外，所有部件都可以通过高压灭菌器或加热到200℃进行灭菌。我们将该采样器应用于位于日本中部长野县Otari村的一口地热井N18-OT-2(1355m，&gt；140℃)。液体中含有丰富的碳酸氢盐…更多(2648ppm)，Na+(1752ppm)和氯(1048ppm)。流体的氧同位素含量(δ^&lt；18&gt；O&lt；Smow&gt；=-8.3permil)显示氧位移，这是水岩相互作用的标志。氢同位素含量(^&lt；18&gt；D=-83permil)相当于当地大气降水。溶解有机碳含量低至4.55±0.53 mg/L，不足以构成地热储深层生物圈。详细的地球化学和同位素模拟表明，该热液是由浅层含钙温泉水与可能来自第四纪Kazafuki-Dake火山附近的深部含CO2地热流体4：1混合而成的，值得注意的是，从温泉中获得了一种新的(门级别)嗜热化学异养丝状菌。详细信息将在发布后披露。另一方面，在井深593米处附着在方解石鳞片上的少量细胞由于数量稀少，无法用卡片-FISH方法进行培养或鉴定。较少

One of the most crucial parameters that limits the habitable depth for extremophiles is temperature. The maximum temperature of growth for hyperthermophile is known to be 121 deg-C but some microbes live on a surface of substrates such as hydrothermal chimneys at temperatures more than 300 deg-C. Therefore, it is presumed that those attached to solid surface may be tolerable to extreme environment such as high temperature.We examined this hypothesis by in-situ sampling from geothermal reservoir using high-temperature, borehole fluid sampler which is tolerant to temperature as high as 300 deg-C. This borehole sampler enables us to get geothermal fluid in-situ to pressure-tight sample chamber (1250 ml) without drastic pressure change. Besides, all the parts can be sterilized either by autoclave or heating up to 200 deg-C.We applied the sampler to a geothermal well N18-OT-2 (1355m,>140 deg-C) that locates in Otari Village, Nagano Prefecture, central Japan. The fluid is rich in bicarbonate … More (2648 ppm), Na^+(1752 ppm) and Cl(1048 ppm). The oxygen isotopic content of the fluid (δ^<18>O<SMOW>=-8.3 permil) shows oxygen shift that is the sign of water rock interaction. The hydrogen isotopic content (^<18>D=-83 permil) is equivalent to local meteoric water. The dissolved organic carbon content (DOC) is as low as 4.55±0.53mg/L which is not high enough to assume intensive deep biosphere within the geothermal reservoir. Detailed geochemical and isotopic modeling indicate that the fluid was formed by 4:1 mixing between shallow, Ca-bearing hot spring water and CO_2 bearing deep geothermal fluid which may come form nearby Quaternary Kazafuki-dake volcano.It is worthy to note that a novel (phylum-level) thermophilic chemo-heterotrophic filamentous bacterium was obtained from the hot spring. Detailed information will be disclosed after publication. On the other hand, small number of cells that attached to the calcite scale of the well at the depth of 593 meters cannot be cultured or identified by CARD-FISH method due to their paucity. Less