Doyle Shawn M, Lin Genmei, Morales-McDevitt Maya, Wade Terry L, Quigg Antonietta, Sylvan Jason B
Department of Oceanography, Texas A&M University, College Station, Texas, USA
School of Marine Sciences, Sun Yat-sen University, Zhuhai, China.
mSystems. 2020 Aug 25;5(4):e00668-20. doi: 10.1128/mSystems.00668-20.
Marine oil spills can impact both coastal and offshore marine environments, but little information is available on how the microbial response to oil and dispersants might differ between these biomes. Here, we describe the compositional and functional response of microbial communities to different concentrations of oil and chemically dispersed oil in coastal and offshore surface waters from the Texas-Louisiana continental shelf. Using a combination of analytical chemistry and 16S rRNA amplicon and metatranscriptomic sequencing, we provide a broad, comparative overview of the ecological response of hydrocarbon-degrading bacteria and their expression of hydrocarbon-degrading genes in marine surface waters over time between two oceanic biomes. We found evidence for the existence of different ecotypes of several commonly described hydrocarbon-degrading bacterial taxa which behaved differentially in coastal and offshore shelf waters despite being exposed to similar concentrations of oil, dispersants, and nutrients. This resulted in the differential expression of catabolic pathways for -alkanes and polycyclic aromatic hydrocarbons (PAHs)-the two major categories of compounds found in crude oil-with preferential expression of -alkane degradation genes in coastal waters while offshore microbial communities trended more toward the expression of PAH degradation genes. This was unexpected as it contrasts with the generally held view that -alkanes, being more labile, are attacked before the more refractory PAHs. Collectively, our results provide new insights into the existence and potential consequences of niche partitioning of hydrocarbon-degrading taxa between neighboring marine environments. In the wake of the Deepwater Horizon oil spill, the taxonomic response of marine microbial communities to oil and dispersants has been extensively studied. However, relatively few studies on the functional response of these microbial communities have been reported, especially in a longitudinal fashion. Moreover, despite the fact that marine oil spills typically impact thousands of square kilometers of both coastal and offshore marine environments, little information is available on how the microbial response to oil and dispersants might differ between these biomes. The results of this study help fill this critical knowledge gap and provide valuable insight into how oil spill response efforts, such as chemically dispersing oil, may have differing effects in neighboring coastal and offshore marine environments.
海洋石油泄漏会对沿海和近海海洋环境造成影响，但关于微生物对石油和分散剂的反应在这些生物群落之间可能存在何种差异的信息却很少。在此，我们描述了德克萨斯 - 路易斯安那大陆架沿海和近海表层水中微生物群落对不同浓度石油和化学分散石油的组成和功能反应。通过结合分析化学、16S rRNA扩增子和宏转录组测序，我们对两个海洋生物群落中随着时间推移，降解烃类细菌的生态反应及其在海洋表层水中烃类降解基因的表达提供了一个广泛的、比较性的概述。我们发现了几种常见的降解烃类细菌分类群存在不同生态型的证据，尽管它们暴露于相似浓度的石油、分散剂和营养物质中，但在沿海和近海大陆架水域中的表现却有所不同。这导致了原油中两类主要化合物——正构烷烃和多环芳烃（PAHs）——分解代谢途径的差异表达，沿海水域中正构烷烃降解基因优先表达，而近海微生物群落则更倾向于表达PAH降解基因。这是出乎意料的，因为这与普遍观点相反，即正构烷烃更不稳定，会在更难降解的PAHs之前被分解。总体而言，我们的结果为相邻海洋环境之间降解烃类分类群的生态位划分的存在及其潜在后果提供了新的见解。在深水地平线石油泄漏事件之后，海洋微生物群落对石油和分散剂的分类学反应已得到广泛研究。然而，关于这些微生物群落功能反应的相对较少的研究被报道，尤其是纵向研究。此外，尽管海洋石油泄漏通常会影响数千平方公里的沿海和近海海洋环境，但关于微生物对石油和分散剂的反应在这些生物群落之间可能存在何种差异的信息却很少。这项研究的结果有助于填补这一关键知识空白，并为诸如化学分散石油等溢油应对措施在相邻沿海和近海海洋环境中可能产生不同影响提供有价值的见解。
