Crude oil oxidation without an electron acceptor; syntrophic hydrocarbon degrading microbes work together to 'crack' a tough problem.

如果你被问到哪个国家拥有最多的石油，你肯定会回答中东的一个大型石油生产国，比如沙特阿拉伯或科威特。尽管这些国家确实拥有巨大的石油储量（仅沙特阿拉伯的Ghawar油田就估计超过2600亿桶），但它们实际上并不是地球上最大的石油储量。这一荣誉是由加拿大西部（阿萨巴斯卡焦油砂）和委内瑞拉（奥里诺科河重油带）的巨大石油矿床所拥有的，每一个都含有超过1万亿桶的石油。美洲的大油田不如中东的大油田为人所知，因为随着地质年代的推移，它们所含的石油已经被生活在石油储层中的微生物生物降解。生物降解去除了最有价值的成分，留下了重质粘稠的焦油状石油，这种石油的生产和提炼比中东的自由流动石油困难得多，成本也高得多。不断上涨的油价和有限的碳氢化合物资源意味着重油油田是一种价值不断增长的经济资源，但它们也为地壳深处的生物圈提供了一个独特的窗口。地球化学测量表明，油藏中的石油生物降解可能是由厌氧碳氢化合物降解细菌引起的，地球化学模型表明，它们的作用速度比在近地表环境中慢数千倍。如果我们要更好地了解导致形成巨大的生物降解石油矿床的过程，需要更积极的实验室规模的厌氧石油生物降解系统。在许多生物降解的石油储层中，厌氧石油降解的主要最终产物似乎是甲烷气体，然而在文献中只有很少的产甲烷石油生物降解的实例。我们最近获得了一种产甲烷微生物菌群，其以在实验室中可测量的速率将石油转化为甲烷（然而这些仍然是非常缓慢的过程）。这项研究的目的是了解什么生物在原油转化为甲烷的过程中具有重要的定量意义，以及什么因素决定了它们在环境中的活动。当我们有了这些信息，好处将是几倍。首先，我们可以开始评估地质时间尺度上石油储层中原油生物降解的地球化学控制。这对石油勘探具有潜在的好处，因为可以避免可能具有有利于石油生物降解的条件的地质构造。它也将被证明是有价值的了解是什么控制泄漏的石油释放到缺氧的地下水或沉积物的命运。甚至有可能将无法用常规手段开采的石油储藏中的残余石油转化为更容易开采的甲烷气体。这项研究将告诉我们哪些生物能够进行产甲烷石油生物降解，它们如何相互作用以及是什么控制着它们的活动。此外，我们还将了解它们将石油转化为甲烷和其他最终产品的速度，这些信息最终可用于预测原油在一系列环境中的行为。

If you were asked which countries have the most oil, you would undoubtedly answer with the name of one of the large oil-producing countries in the Middle East such as Saudi Arabia or Kuwait. Although these countries do have vast oil reserves (Saudi Arabia's Ghawar oil field alone, is estimated to contain in excess of 260 billion barrels) they are not actually the largest oil deposits on Earth. This honour is held by the gigantic petroleum deposits in Western Canada (Athabasca tar sands) and Venezuela (Orinoco heavy oil belt) which each contain well over 1 trillion barrels of oil. The giant oil fields in the Americas are less well known than those in the Middle East because, over geological time, the oil which they contain has been biodegraded by microorganisms living in the petroleum reservoirs. Biodegradation removes the most valuable components leaving behind heavy viscous tar-like oil which is much more difficult and expensive to produce and refine than the free-flowing oils from the Middle East. Increasing oil prices and finite hydrocarbon resources mean that heavy oil fields represent an economic resource of growing value, but they also provide a unique window on the biosphere found deep within the Earth's crust. Geochemical measurements have shown that petroleum biodegradation in oil reservoirs is probably caused by anaerobic hydrocarbon-degrading bacteria and geochemical modelling suggests that they operate at rates thousands of times slower than they do in near surface environments. If we are to better understand the processes that lead to the formation of giant biodegraded oil deposits, more active experimental laboratory-scale anaerobic oil biodegradation systems are required. A major end product of anaerobic oil degradation in many biodegraded petroleum reservoirs appears to be methane gas, however there are only very few examples of methanogenic oil biodegradation in the literature. We have recently obtained a methanogenic microbial consortium that converts oil to methane at rates which are measurable in the laboratory (these are however still very slow processes). The objective of this research is to understand what organisms are quantitatively significant in the conversion of crude oil to methane and what factors dictate their activity in the environment. When we have this information the benefits will be several fold. Firstly we can begin to assess the geochemical controls on crude oil biodegradation in petroleum reservoirs on geological timescales. This has potential benefits for petroleum exploration where geological formations that may have had conditions conducive to petroleum biodegradation may be avoided. It will also prove valuable for understanding what controls the fate of spilled petroleum released to anoxic groundwater or sediments. There is even the possibility that residual oil in petroleum reservoirs, which cannot be recovered by conventional means, could be converted to more readily recoverable methane gas. This research will tell us what organisms are capable of methanogenic oil biodegradation, how they interact with each other and what controls their activity. In addition we will learn how quickly they can convert oil to methane and other end products, information that can ultimately be used to predict the behaviour of crude oil in a range of environments.