Abstract To identify hydrocarbon-degrading microorganisms contributing to the formation of heavy oil we investigated the microbial community composition in different types of crude oils from oil-production facilities and in crude oil and asphalt from different natural seeps from the Kurdistan Region of Iraq (KRI). Crude oils from five out of six production facilities did not contain microorganisms detectable by 16S rRNA gene PCR amplicon sequencing likely reflecting a low microbial abundance in these samples. Crude oil and asphalt from the natural seeps hosted diverse microbial communities. The same phylotypes of uncultivated Deferribacteres and Thermodesulfobacteraceae were predominant community members across crude oils and asphalts from separate geographical locations. Soils surrounding seeps did not contain these phylotypes suggesting that they originate from the subsurface and although they seem commonly detected in hydrocarbon-rich environments their role in hydrocarbon-degradation is unknown. GC-MS analyses showed that mainly aromatic hydrocarbons were present in the crude oil and asphalt and that they were undergoing biodegradation - likely with sulfate and nitrate as terminal oxidants. In agreement, only bssA gene, but not assA gene-carrying microorganisms were detectable in the analyzed sampled. Overall our study identified several abundant uncultivated taxa with likely roles in transformation of nitrate, sulfate and hydrocarbons.

中文翻译：

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伊拉克库尔德斯坦地区原油和沥青中的微生物群落组成

摘要 为了鉴定有助于形成重油的烃降解微生物，我们研究了来自伊拉克库尔德斯坦地区 (KRI) 的石油生产设施的不同类型原油以及来自不同天然渗漏的原油和沥青中的微生物群落组成。 . 来自六个生产设施中的五个生产设施的原油不含可通过 16S rRNA 基因 PCR 扩增子测序检测到的微生物，这可能反映了这些样品中微生物丰度低。来自天然渗漏的原油和沥青承载着不同的微生物群落。在不同地理位置的原油和沥青中，未培养的去铁细菌和嗜热脱硫杆菌科的相同系统发育是主要的群落成员。渗漏周围的土壤不包含这些系统发育型，表明它们起源于地下，尽管它们似乎在富含碳氢化合物的环境中很常见，但它们在碳氢化合物降解中的作用尚不清楚。GC-MS 分析表明，原油和沥青中主要存在芳烃，并且它们正在经历生物降解——可能以硫酸盐和硝酸盐作为末端氧化剂。一致地，在分析的采样中只能检测到 bssA 基因，而不能检测到携带 assA 基因的微生物。总体而言，我们的研究确定了几种丰富的未开发分类群，它们可能在硝酸盐、硫酸盐和碳氢化合物的转化中发挥作用。GC-MS 分析表明，原油和沥青中主要存在芳烃，并且它们正在经历生物降解——可能以硫酸盐和硝酸盐作为末端氧化剂。一致地，在分析的采样中只能检测到 bssA 基因，而不能检测到携带 assA 基因的微生物。总体而言，我们的研究确定了几种丰富的未开发分类群，它们可能在硝酸盐、硫酸盐和碳氢化合物的转化中发挥作用。GC-MS 分析表明，原油和沥青中主要存在芳烃，并且它们正在经历生物降解——可能以硫酸盐和硝酸盐作为末端氧化剂。一致地，在分析的采样中只能检测到 bssA 基因，而不能检测到携带 assA 基因的微生物。总体而言，我们的研究确定了几种丰富的未开发分类群，它们可能在硝酸盐、硫酸盐和碳氢化合物的转化中发挥作用。