Cheng Lei, Shi Shengbao, Li Qiang, Chen Jianfa, Zhang Hui, Lu Yahai
College of Resources and Environmental Sciences, China Agricultural University, Beijing, 100193, China; Key Laboratory of Development and Application of Rural Renewable Energy, Biogas Institute of Ministry of Agriculture, Chengdu, 610041, China.
State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum (Beijing), Beijing, 102200, China.
PLoS One. 2014 Nov 19;9(11):e113253. doi: 10.1371/journal.pone.0113253. eCollection 2014.
Although methanogenic degradation of hydrocarbons has become a well-known process, little is known about which crude oil tend to be degraded at different temperatures and how the microbial community is responded. In this study, we assessed the methanogenic crude oil degradation capacity of oily sludge microbes enriched from the Shengli oilfield under mesophilic and thermophilic conditions. The microbial communities were investigated by terminal restriction fragment length polymorphism (T-RFLP) analysis of 16S rRNA genes combined with cloning and sequencing. Enrichment incubation demonstrated the microbial oxidation of crude oil coupled to methane production at 35 and 55°C, which generated 3.7±0.3 and 2.8±0.3 mmol of methane per gram oil, respectively. Gas chromatography-mass spectrometry (GC-MS) analysis revealed that crude oil n-alkanes were obviously degraded, and high molecular weight n-alkanes were preferentially removed over relatively shorter-chain n-alkanes. Phylogenetic analysis revealed the concurrence of acetoclastic Methanosaeta and hydrogenotrophic methanogens but different methanogenic community structures under the two temperature conditions. Candidate divisions of JS1 and WWE 1, Proteobacteria (mainly consisting of Syntrophaceae, Desulfobacteraceae and Syntrophorhabdus) and Firmicutes (mainly consisting of Desulfotomaculum) were supposed to be involved with n-alkane degradation in the mesophilic conditions. By contrast, the different bacterial phylotypes affiliated with Caldisericales, "Shengli Cluster" and Synergistetes dominated the thermophilic consortium, which was most likely to be associated with thermophilic crude oil degradation. This study revealed that the oily sludge in Shengli oilfield harbors diverse uncultured microbes with great potential in methanogenic crude oil degradation over a wide temperature range, which extend our previous understanding of methanogenic degradation of crude oil alkanes.
尽管烃类的产甲烷降解已成为一个广为人知的过程，但对于哪些原油在不同温度下易于降解以及微生物群落如何响应却知之甚少。在本研究中，我们评估了在中温和嗜热条件下从胜利油田富集的含油污泥微生物的产甲烷原油降解能力。通过对16S rRNA基因进行末端限制性片段长度多态性（T-RFLP）分析并结合克隆和测序来研究微生物群落。富集培养表明，在35℃和55℃下原油能被微生物氧化并伴有甲烷生成，分别产生每克油3.7±0.3和2.8±0.3 mmol的甲烷。气相色谱-质谱（GC-MS）分析表明，原油正构烷烃明显降解，高分子量正构烷烃比相对较短链的正构烷烃更易被去除。系统发育分析表明，在两种温度条件下均存在乙酸营养型的甲烷八叠球菌属和氢营养型产甲烷菌，但产甲烷群落结构不同。推测JS1和WWE 1候选类群、变形菌门（主要由互营杆菌科、脱硫杆菌科和互营栖热菌属组成）和厚壁菌门（主要由脱硫肠状菌属组成）参与中温条件下的正构烷烃降解。相比之下，与热脱硫线菌目、“胜利菌群”和互养菌纲相关的不同细菌系统型主导了嗜热菌群，这很可能与嗜热原油降解有关。本研究表明，胜利油田的含油污泥含有多种未培养微生物，在较宽温度范围内具有巨大的产甲烷原油降解潜力，这扩展了我们之前对原油烷烃产甲烷降解的认识。
