Department of Chemical Engineering, University of Washington , Seattle , USA ; Biotechnological Management of Resources Network, Institute of Ecology , A.C. Xalapa, Veracruz , Mexico.
Department of Chemical Engineering, University of Washington , Seattle , USA ; eScience Institute, University of Washington , Seattle , USA.
PeerJ. 2015 Feb 24;3:e801. doi: 10.7717/peerj.801. eCollection 2015.
We have previously observed that methane supplied to lake sediment microbial communities as a substrate not only causes a response by bona fide methanotrophic bacteria, but also by non-methane-oxidizing bacteria, especially by members of the family Methylophilaceae. This result suggested that methane oxidation in this environment likely involves communities composed of different functional guilds, rather than a single type of microbe. To obtain further support for this concept and to obtain further insights into the factors that may define such partnerships, we carried out microcosm incubations with sediment samples from Lake Washington at five different oxygen tensions, while methane was supplied at the same concentration in each. Community composition was determined through 16S rRNA gene amplicon sequencing after 10 and 16 weeks of incubation. We demonstrate that, in support of our prior observations, the methane-consuming communities were represented by two major types: the methanotrophs of the family Methylococcaceae and by non-methanotrophic methylotrophs of the family Methylophilaceae. However, different species persisted under different oxygen tensions. At high initial oxygen tensions (150 to 225 µM) the major players were, respectively, species of the genera Methylosarcina and Methylophilus, while at low initial oxygen tensions (15 to 75 µM) the major players were Methylobacter and Methylotenera. These data suggest that oxygen availability is at least one major factor determining specific partnerships in methane oxidation. The data also suggest that speciation within Methylococcaceae and Methylophilaceae may be driven by niche adaptation tailored toward specific placements within the oxygen gradient.
我们之前观察到，作为一种基质提供给湖泊沉积物微生物群落的甲烷不仅会引起真正的甲烷氧化菌的反应，也会引起非甲烷氧化菌的反应，尤其是甲基杆菌科的成员。这一结果表明，这种环境中的甲烷氧化可能涉及由不同功能类群组成的群落，而不是单一类型的微生物。为了进一步支持这一概念，并深入了解可能定义这种伙伴关系的因素，我们在五个不同的氧张力下，对来自华盛顿湖的沉积物样本进行了微宇宙培养，同时在每个样本中以相同的浓度供应甲烷。在 10 和 16 周的培养后，通过 16S rRNA 基因扩增子测序来确定群落组成。我们证明，支持我们之前的观察结果，甲烷消耗群落由两种主要类型代表：甲基球菌科的甲烷氧化菌和甲基杆菌科的非甲烷氧化甲基营养菌。然而，不同的物种在不同的氧张力下持续存在。在初始氧张力较高（150 至 225 µM）时，主要的参与者分别是甲基弧菌属和甲基单胞菌属的物种，而在初始氧张力较低（15 至 75 µM）时，主要的参与者是甲基杆菌属和甲基硫杆菌属。这些数据表明，氧气供应至少是决定甲烷氧化特定伙伴关系的一个主要因素。这些数据还表明，甲基球菌科和甲基杆菌科内的物种形成可能是由针对氧气梯度内特定位置的生态位适应驱动的。
