Hydrogen Generation in the Deep, Hot Biosphere

深部炎热生物圈中的氢气生成

• 批准号: NE/H02042X/1
• 负责人: Ronald Parkes
• 金额: $ 82.53万
• 依托单位: CARDIFF UNIVERSITY
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2011
• 资助国家: 英国
• 起止时间: 2011 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FH02042X%2F1
• 关键词: Hydrogen; Generation; Deep; Hot; Biosphere

The discovery of the Subsurface LithoAutotrophic Microbial Ecosystem (SLiME) in basalt formations in 1995, seemingly using hydrogen formed from water rock interactions, was of great significance as this anaerobic community could be independent of surface photosynthesis, both organic matter and oxygen. This potentially significant energy supply might also explain the surprisingly large numbers of prokaryotes found in subsurface terrestrial environment (at least to 3 km depth), despite extreme conditions and lack of obvious energy supply. It also has profound astrobiological significance as a mechanism for subsurface life in planets even with surface conditions that are unsuitable for life. However, the significance of this hydrogen generation is controversial having being criticized as being a negligible reaction in the environment (conditions too alkaline, restricted by limited reduced iron concentrations in minerals and by its dependence on the production of fresh reactive surfaces). However, hydrogen formation has also been detected at depth in earthquake fault zones and there is indirect evidence that this is used by subsurface prokaryotes to produce methane. The mechanism of hydrogen formation in this case is thought to be due to mechanochemistry as a result of subsurface fracturing of rocks in earthquake zones. If this is true then with some greater than 20,000 earthquakes a year any rock type could potentially produce hydrogen making a substantial SLiME community distinctly more possible. In addition, we have demonstrated that some prokaryotes may actually speed-up hydrogen formation from minerals in sediment slurries, including hydrogen generation from pure silica sand. As silicates make up ~95% of the Earth's crust this could potentially be a significant source of hydrogen. We intend to investigate further these mechanisms of hydrogen formation by testing a range of common minerals and conditions for hydrogen generation, including at increasing temperatures to simulate the heating that occurs due to sediment burial. We will determine whether microbial processes are stimulated by hydrogen formation and identify and culture the microbes involved. These enriched microbes will then be used with pure minerals to investigate their involvement and ability to use the mineral as an energy source in more detail. Some high pressure experiments will enable temperatures up to 150oC to be investigated. This is too high for microbes (max ~120oC) but may produce hydrogen and other compounds which can diffuse upwards to feed the base of the biosphere. Novel sealed rock crushing experiments will also be conducted (30 - 120oC) to test whether just cracking of rocks can produce enough hydrogen to feed a microbial population.

1995年在玄武岩地层中发现的地下岩石自养微生物生态系统（SLiME），似乎是利用水-岩石相互作用形成的氢，具有重要意义，因为这种厌氧群落可以独立于表面光合作用，有机物和氧气。尽管条件极端且缺乏明显的能量供应，但这种潜在的重要能量供应也可能解释在陆地地下环境（至少3公里深处）中发现的大量原核生物。它也具有深远的天体生物学意义，作为行星地下生命的机制，即使表面条件不适合生命。然而，这种氢生成的意义是有争议的，因为它被批评为在环境中是可忽略的反应（条件太碱性，受到矿物中有限的还原铁浓度的限制，并且受到其对新鲜反应性表面的产生的依赖性的限制）。然而，在地震断层带的深处也发现了氢的形成，有间接证据表明，地下原核生物利用氢产生甲烷。在这种情况下，氢的形成机制被认为是由于地震区岩石的地下破裂导致的机械化学。如果这是真的，那么每年大约有超过20，000次地震，任何岩石类型都可能产生氢气，使大量的SLiME社区明显更有可能。此外，我们已经证明，一些原核生物实际上可能会加速从沉积物泥浆中的矿物中生成氢，包括从纯硅砂中生成氢。由于硅酸盐占地壳的95%，这可能是氢的重要来源。我们打算通过测试一系列常见的矿物和产氢条件，包括在升高的温度下模拟沉积物埋藏引起的加热，进一步研究这些氢形成机制。我们将确定微生物过程是否受到氢气形成的刺激，并识别和培养所涉及的微生物。然后，这些富集的微生物将与纯矿物一起使用，以更详细地研究它们的参与和使用矿物作为能源的能力。一些高压实验将能够研究高达150 oC的温度。这对于微生物来说太高了（最高~ 120摄氏度），但可能会产生氢和其他化合物，这些化合物可以向上扩散以供给生物圈的底部。还将进行新的密封岩石破碎实验（30 - 120 ℃），以测试岩石的破裂是否能产生足够的氢来喂养微生物种群。

项目成果

Rock-crushing derived hydrogen directly supports a methanogenic community: significance for the deep biosphere.

岩石破碎产生的氢直接支持产甲烷群落：对深层生物圈的意义。

• DOI: 10.1111/1758-2229.12723
• 发表时间: 2019
• 期刊: Environmental microbiology reports
• 影响因子: 3.3
• 作者: Parkes RJ

Prokaryotes stimulate mineral H2 formation for the deep biosphere and subsequent thermogenic activity

原核生物刺激深层生物圈矿物质 H2 的形成以及随后的产热活动

• DOI: 10.1130/g31598.1
• 发表时间: 2011
• 期刊: Geology
• 影响因子: 5.8
• 作者: Parkes R

Complex coupled metabolic and prokaryotic community responses to increasing temperatures in anaerobic marine sediments: critical temperatures and substrate changes.

• DOI: 10.1093/femsec/fiv084
• 发表时间: 2015-08
• 期刊: FEMS microbiology ecology
• 影响因子: 4.2
• 作者: Roussel EG;Cragg BA;Webster G;Sass H;Tang X;Williams AS;Gorra R;Weightman AJ;Parkes RJ
• 通讯作者: Parkes RJ

Survival of Desulfotomaculum spores from estuarine sediments after serial autoclaving and high-temperature exposure.

• DOI: 10.1038/ismej.2014.190
• 发表时间: 2015-03-17
• 期刊: The ISME journal
• 作者: O'Sullivan LA;Roussel EG;Weightman AJ;Webster G;Hubert CR;Bell E;Head I;Sass H;Parkes RJ
• 通讯作者: Parkes RJ