Microbial Resources Division, Research Center for Chemistry, Biology and Agriculture (CPQBA), University of Campinas - UNICAMP, Campinas, Brazil; Institute of Biology, University of Campinas - UNICAMP, Campinas, Brazil.
Microbial Resources Division, Research Center for Chemistry, Biology and Agriculture (CPQBA), University of Campinas - UNICAMP, Campinas, Brazil; Institute of Biology, University of Campinas - UNICAMP, Campinas, Brazil.
Sci Total Environ. 2020 May 1;715:136646. doi: 10.1016/j.scitotenv.2020.136646. Epub 2020 Jan 15.
Microbial biodegradation of hydrocarbons in petroleum reservoirs has major consequences in the petroleum value and quality. The identification of microorganisms capable of in-situ degradation of hydrocarbons under the reservoir conditions is crucial to understand microbial roles in hydrocarbon transformation and the impact of oil exploration and production on energy resources. The aim of this study was to profile the metagenome of microbial communities in crude oils and associated formation water from two high temperature and relatively saline oil-production wells, where one has been subjected to water flooding (BA-2) and the other one is considered pristine (BA-1). The microbiome was studied in the fluids using shotgun metagenome sequencing. Distinct microbial compositions were revealed when comparing pristine and water flooded oil wells in contrast to the similar community structures observed between the aqueous and oil fluids from the same well (BA-2). The equal proportion of archaea and bacteria together with the greater anaerobic hydrocarbon degradation potential in the BA-1 pristine but degraded reservoir contrasted with the predominance of bacteria over archaea, aerobic pathways and lower frequency of anaerobic degradation genes in the BA-2 water flooded undegraded well. Our results suggest that Syntrophus, Syntrophomonas, candidatus Atribacteria and Synergistia, in association with mainly acetoclastic methanogenic archaea of the genus Methanothrix, were collectively responsible for the oil biodegradation observed in the pristine petroleum well BA-1. Conversely, the microbial composition of the water flooded oil well BA-2 was mainly dominated by the fast-growing and putatively aerobic opportunists Marinobacter and Marinobacterium. This presumable allochthonous community introduced a greater metabolic versatility, although oil biodegradation has not been detected hitherto perhaps due to in-reservoir unfavorable physicochemical conditions. These findings provide a better understanding of the petroleum reservoir microbiomes and their potential roles in biogeochemical processes occurring in environments with different geological and oil recovery histories.
油藏中微生物对碳氢化合物的生物降解对石油的价值和质量有重大影响。鉴定能够在油藏条件下原位降解碳氢化合物的微生物对于了解微生物在碳氢化合物转化中的作用以及石油勘探和生产对能源资源的影响至关重要。本研究的目的是对来自两口高温高盐油生产井的原油和伴生地层水的微生物群落进行宏基因组分析，其中一口井经历了注水（BA-2），另一口井被认为是原始的（BA-1）。使用鸟枪法宏基因组测序研究了微生物组在流体中的情况。与同一井的水相和油相之间观察到的相似群落结构相比，原始和注水油井之间显示出截然不同的微生物组成。BA-1 原始但降解的储层中，古菌和细菌的比例相等，并且具有更大的厌氧烃降解潜力，而 BA-2 注水未降解井中，细菌占优势，有氧途径和较低频率的厌氧降解基因。我们的结果表明，Syntrophus、Syntrophomonas、candidatus Atribacteria 和 Synergistia 与主要为产乙酸甲烷古菌属 Methanothrix 的甲烷菌共同作用，是导致 BA-1 原始石油井中观察到的石油生物降解的原因。相反，注水油井 BA-2 的微生物组成主要由生长迅速且可能为需氧的机会主义者 Marinobacter 和 Marinobacterium 主导。这个假定的外来群落引入了更大的代谢多样性，尽管迄今为止尚未检测到石油生物降解，这可能是由于油藏中不利的物理化学条件所致。这些发现为了解油藏微生物组及其在具有不同地质和采油历史的环境中发生的生物地球化学过程中的潜在作用提供了更好的认识。
