OILSPORE

微生物是地球上最丰富的生命形式。据估计，大约有一万亿亿亿亿万个个体有机体，分别属于两个主要的微生物类群(细菌和古生菌)。这是已知宇宙中恒星估计数量的100万倍。据信，这些庞大的种群中的大部分都是在远离地面和海底的深层沉积物中发现的。人们很容易认为这个埋藏着生物(微生物)多样性的巨大储存库与人类无关，但事实并非如此。这个陆地内的微生物群被称为“深层生物圈”，它是物质在地质时间尺度上循环的中心。更紧迫的问题是，某些深层生物圈生物在改变石油储藏层中的原地石油方面发挥了作用。世界上大多数石油(例如加拿大西部巨大的沥青砂矿藏)在人类开采出第一滴原油之前很久就已经被微生物就地降解了。我们小组的研究发现了导致石油储藏中原油生物降解的微生物过程，并确定了促进生物降解的生物和地质因素。其中一个因素是温度。地壳温度每100米随深度增加约2-3摄氏度，温度高于90摄氏度的储油层不会受到生物降解的影响。然而，更冷、更浅的水库并不总是生物降解的。这些未退化的、凉爽的浅层储层曾经生活在较深的地方，但由于地质隆升而移动到较浅的深度。它们似乎没有被石油降解菌重新定居，这些储油层中的石油保持完好。这种对油藏的瞬时加热过程杀死了现存的石油降解微生物群，被称为古不透明潜伏化。北极的研究为了解油藏深层生物圈提供了一个窗口。北极寒冷沉积物中的细菌在50摄氏度左右具有最佳活性，可能来自泄漏的温暖油藏，因为它们的近亲以前是在热油井中发现的。这些有机体形成的孢子对极端环境具有高度的抵抗力，并充当生存胶囊，保护细菌从地球深处旅行。这些细菌在没有氧气的情况下茁壮成长(厌氧菌)，孢子抵抗氧气的暴露。英国港口的沉积物中含有芽胞形成细菌，这种细菌在没有氧气的情况下降解原油，为细菌和石油储藏之间提供了另一种联系。该项目旨在确定形成孢子、降解石油的细菌和北极细菌最终是否来自石油储集层，以及古不透明杀菌过程是否会杀死它们并防止它们播种地表沉积物。该项目专注于生物学和地质学之间的基础科学，具有实际意义。来自深层生物圈的降解碳氢化合物的厌氧菌的供应对表层沉积物中的微生物多样性有影响，这些细菌可能在耗氧沉积物(即沿海沉积物以及Macondo井口附近的墨西哥湾深海海底)的石油清理中发挥作用。相关细菌还会在油层酸化过程中产生有毒气体硫化氢，从而给石油行业带来问题。这降低了石油的价值，并对工人构成了危险。英国拥有一个主要的海上石油行业，为就业和经济繁荣做出了重大贡献。在化石碳能源经济向可再生能源经济过渡期间，仍然需要创新的业务做法，以减少石油生产和勘探对环境的影响；这在很大程度上是基于对与石油生产和石油在环境中的降解有关的微生物的了解。

Microorganisms are the most abundant life forms on Earth. It is estimated that there are around 10 thousand, billion, billion, billion individual organisms belonging to two main microbial groups (the bacteria and archaea). This is 1 million times more than the estimated number of stars in the known Universe. It is believed that most of this vast population is found in deep sediments far below the ground and the sea floor. It is easy to think that this huge repository of buried biological (microbial) diversity is irrelevant to mankind, but nothing could be further from the truth.This intra-terrestrial microbiota has been coined the 'deep biosphere' and it is central to the cycling of matter over geological timescales. Of more immediate concern is the role that certain deep biosphere organisms have played in modifying oil in situ in petroleum reservoirs. Most of the world's oil (e.g. the giant tar sand deposits in Western Canada) has been degraded by microbes in situ long before humans recovered the first drop of crude oil. Research from our group has uncovered the microbial processes responsible for crude oil biodegradation in petroleum reservoirs and identified biological and geological factors that promote biodegradation. One of these factors is temperature. The temperature of the Earth's crust increases with depth by approximately 2-3 C every 100 meters and petroleum reservoirs at temperatures above 90 C are not subject to biodegradation. However cooler, shallower reservoirs are not always biodegraded. These non-degraded, cool shallow reservoirs once resided at greater depths but have been moved by geological uplift to shallower depths. It appears that they are not re-colonized by oil-degrading bacteria and the oil in these reservoirs remains intact. This process of transient heating of a petroleum reservoir which kills the resident oil-degrading microbiota has been termed palaeopasteurization.Research in the Arctic has provided a window into the petroleum reservoir deep biosphere. Cold Arctic sediments harbour bacteria that have optimal activity at around 50 C and may have come from leaky warm petroleum reservoirs because their closest relatives were previously identified in hot oil wells. These organisms form spores which are highly resistant to environmental extremes and act as survival capsules that protect the bacteria on their journey from deep within the Earth. These bacteria thrive without oxygen (anaerobes) and the spores resist exposure to oxygen. Sediments in the UK harbour spore-forming bacteria that degrade crude oil without oxygen, providing another link between bacteria and petroleum reservoirs. This project aims to determine if spore-forming oil-degrading and Arctic bacteria ultimately derive from petroleum reservoirs and if the process of palaeopasteurization kills them and prevents them seeding surface sediments.The project focuses on fundamental science at the interface between biology and geology and has practical implications. A supply of hydrocarbon degrading anaerobes from the deep biosphere has implications for microbial diversity in surface sediments where these bacteria may play a role in oil clean up in oxygen depleted sediments (i.e., in coastal sediments but also the deep Gulf of Mexico seafloor near the Macondo wellhead). Related bacteria also cause problems in the oil industry by producing the toxic gas hydrogen sulphide in a process known as reservoir souring. This reduces the value of oil and poses a hazard to workers. The UK hosts a major offshore oil industry that contributes significantly to employment and economic prosperity. During the transition between a fossil carbon energy economy and a renewable energy economy, the need remains for innovative operational practices to reduce the environmental impact of oil production and exploration; much of this is underpinned by an understanding of microorganisms associated with oil production and oil degradation in the environment.