Techtmann Stephen M, Zhuang Mobing, Campo Pablo, Holder Edith, Elk Michael, Hazen Terry C, Conmy Robyn, Santo Domingo Jorge W
Department of Biological Sciences, Michigan Technological University, Houghton, Michigan, USA.
Department of Biomedical, Chemical and Environmental Engineering, University of Cincinnati, Cincinnati, Ohio, USA.
Appl Environ Microbiol. 2017 May 1;83(10). doi: 10.1128/AEM.03462-16. Print 2017 May 15.
To better understand the impacts of Corexit 9500 on the structure and activity levels of hydrocarbon-degrading microbial communities, we analyzed next-generation 16S rRNA gene sequencing libraries of hydrocarbon enrichments grown at 5 and 25°C using both DNA and RNA extracts as the sequencing templates. Oil biodegradation patterns in both 5 and 25°C enrichments were consistent with those reported in the literature (i.e., aliphatics were degraded faster than aromatics). Slight increases in biodegradation were observed in the presence of Corexit at both temperatures. Differences in community structure were observed between treatment conditions in the DNA-based libraries. The 25°C consortia were dominated by , , , , and species, while the 5°C consortia were dominated by several species of the genera , , and Most of these genera have been linked to hydrocarbon degradation and have been observed after oil spills. and , known aromatic degraders, were also found in these enrichments. The addition of Corexit did not have an effect on the active bacterial community structure of the 5°C consortia, while at 25°C, a decrease in the relative abundance of was observed. At 25°C, , , and were present at higher relative abundances in the RNA than DNA libraries, suggesting that they were active in degradation. Similarly, was greatly stimulated by the addition of oil at 5°C. While dispersants such as Corexit 9500 can be used to treat oil spills, there is still debate on the effectiveness on enhancing oil biodegradation and its potential toxic effect on oil-degrading microbial communities. The results of this study provide some insights on the microbial dynamics of hydrocarbon-degrading bacterial populations in the presence of Corexit 9500. Operational taxonomic unit (OTU) analyses indicated that several OTUs were inhibited by the addition of Corexit. Conversely, a number of OTUs were stimulated by the addition of the dispersant, many of which were identified as known hydrocarbon-degrading bacteria. The results highlight the value of using RNA-based methods to further understand the impact of dispersant on the overall activity of different hydrocarbon-degrading bacterial groups.
为了更好地理解Corexit 9500对烃降解微生物群落结构和活性水平的影响，我们分析了在5°C和25°C下培养的烃富集物的下一代16S rRNA基因测序文库，使用DNA和RNA提取物作为测序模板。5°C和25°C富集物中的石油生物降解模式与文献报道一致（即脂肪族比芳香族降解得更快）。在两个温度下，Corexit存在时均观察到生物降解略有增加。基于DNA的文库中，处理条件之间观察到群落结构差异。25°C的聚生体以 、 、 、 和 物种为主，而5°C的聚生体以 、 和 属的几个物种为主。这些属中的大多数都与烃降解有关，并且在石油泄漏后被观察到。已知的芳香族降解菌 和 也在这些富集物中被发现。添加Corexit对5°C聚生体的活性细菌群落结构没有影响，而在25°C时，观察到 的相对丰度下降。在25°C时， 、 和 在RNA文库中的相对丰度高于DNA文库，表明它们在降解中具有活性。同样，在5°C时添加油极大地刺激了 。虽然像Corexit 9500这样的分散剂可用于处理石油泄漏，但关于其增强石油生物降解的有效性及其对石油降解微生物群落的潜在毒性作用仍存在争议。本研究结果为Corexit 9500存在下烃降解细菌种群的微生物动态提供了一些见解。操作分类单元（OTU）分析表明，添加Corexit抑制了几个OTU。相反，添加分散剂刺激了许多OTU，其中许多被鉴定为已知的烃降解细菌。结果突出了使用基于RNA的方法进一步了解分散剂对不同烃降解细菌群体整体活性影响的价值。
