Stagars Marion H, Mishra Sonakshi, Treude Tina, Amann Rudolf, Knittel Katrin
Department of Molecular Ecology, Max Planck Institute for Marine MicrobiologyBremen, Germany.
Department of Marine Biogeochemistry, GEOMAR - Helmholtz Centre for Ocean Research KielKiel, Germany.
Front Microbiol. 2017 Apr 28;8:764. doi: 10.3389/fmicb.2017.00764. eCollection 2017.
Anaerobic microbial hydrocarbon degradation is a major biogeochemical process at marine seeps. Here we studied the response of the microbial community to petroleum seepage simulated for 190 days in a sediment core from the Caspian Sea using a sediment-oil-flow-through (SOFT) system. Untreated (without simulated petroleum seepage) and SOFT sediment microbial communities shared 43% bacterial genus-level 16S rRNA-based operational taxonomic units (OTU) but shared only 23% archaeal OTU. The community differed significantly between sediment layers. The detection of fourfold higher deltaproteobacterial cell numbers in SOFT than in untreated sediment at depths characterized by highest sulfate reduction rates and strongest decrease of gaseous and mid-chain alkane concentrations indicated a specific response of hydrocarbon-degrading Deltaproteobacteria. Based on an increase in specific CARD-FISH cell numbers, we suggest the following groups of sulfate-reducing bacteria to be likely responsible for the observed decrease in aliphatic and aromatic hydrocarbon concentration in SOFT sediments: clade SCA1 for propane and butane degradation, clade LCA2 for mid- to long-chain alkane degradation, clade Cyhx for cycloalkanes, pentane and hexane degradation, and relatives of for toluene degradation. Highest numbers of archaea of the genus were found in the methanogenic zone of the SOFT core where we detected preferential degradation of long-chain hydrocarbons. Sequencing of , a marker gene for alkane degradation encoding (1-methylalkyl)succinate synthase, revealed a low diversity in SOFT sediment with two abundant species-level MasD OTU.
厌氧微生物烃降解是海洋渗漏处的一个主要生物地球化学过程。在此，我们使用沉积物 - 油 - 流通（SOFT）系统，研究了里海沉积物岩心中微生物群落对模拟石油渗漏190天的响应。未处理（无模拟石油渗漏）的沉积物微生物群落与SOFT沉积物微生物群落共享43%基于细菌属水平16S rRNA的操作分类单元（OTU），但仅共享23%的古菌OTU。不同沉积层的群落存在显著差异。在硫酸盐还原速率最高且气态和中链烷烃浓度下降最强的深度处，检测到SOFT中的δ变形菌细胞数比未处理沉积物中的高四倍，这表明烃降解δ变形菌有特定响应。基于特定CARD - FISH细胞数的增加，我们认为以下几组硫酸盐还原菌可能是导致SOFT沉积物中脂肪族和芳香族烃浓度下降的原因：SCA1分支负责丙烷和丁烷降解，LCA2分支负责中长链烷烃降解，Cyhx分支负责环烷烃、戊烷和己烷降解，以及 分支的亲缘种负责甲苯降解。在SOFT岩心的产甲烷区发现了 属古菌的最高数量，在那里我们检测到长链烃的优先降解。对编码（1 - 甲基烷基）琥珀酸合酶的烷烃降解标记基因 进行测序，结果显示SOFT沉积物中的多样性较低，有两个丰富的种水平MasD OTU。
