Synthetic methanogenic communities reveal differential impact of ecological perturbations on aceto- and hydrogeno-trophic methanogens
Synthetic methanogenic communities reveal differential impact of ecological perturbations on aceto- and hydrogeno-trophic methanogens
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DOI：
10.1101/307041
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发表时间：
2018-04
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影响因子：
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通讯作者：
J. Chen;Matthew John Wade;J. Dolfing;Orkun S. Soyer
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作者：
J. Chen;Matthew John Wade;J. Dolfing;Orkun S. Soyer
合成微生物群落提供了可在特定条件下研究的简化微生物生态。在这里，我们使用这种方法来研究支撑厌氧消化群落的相互作用，并涉及硫酸盐还原剂（Desulfovibrio vulgaris）、乙酰（Methanosarcina barkeri）和氢营养（Methanococcus maripaludis）产甲烷菌的关键微生物种群。我们创建了这些物种的所有可能的混合培养物组合，并分析了每个系统在多个亚培养物和不同硫酸盐水平下的稳定性和生产力，以强电子受体可用性的形式模拟生态扰动。我们发现，所有三个物种都可以在没有硫酸盐的情况下共存，并且与共培养相比，系统生产力（以乳酸生产甲烷的形式）几乎增加了两倍。随着硫酸盐可用性的增加，共存受到干扰，两个产甲烷种群均呈现减少趋势。有趣的是，我们发现，尽管系统中持续存在乙酸盐，但乙酸营养型产甲烷菌更容易被硫酸盐扰动破坏。我们表明，这是由于巴克氏菌代谢转向增加氢与乙酸盐的共同利用，我们通过单一培养物实验和共培养物中的质量平衡计算验证了这一点。我们得出的结论是，氢是氢营养产甲烷作用和醋营养产甲烷作用的关键因素，并且在强电子受体可用性的常见生态扰动下可以对这些种群产生不同的影响。这些发现将有助于设计更大的合成群落，以用于生物降解的特定应用，并了解动物肠道、沉积物和生物反应器中发现的复杂厌氧消化群落。
Synthetic microbial communities provide reduced microbial ecologies that can be studied under defined conditions. Here, we use this approach to study the interactions underpinning anaerobic digestion communities and involving the key microbial populations of a sulfate reducer (Desulfovibrio vulgaris), and aceto-(Methanosarcina barkeri) and hydrogenotrophic (Methanococcus maripaludis) methanogens. We create all possible mixed culture combinations of these species and analyse the stability and productivity of each system over multiple sub-culturings and under different sulfate levels, mimicking ecological perturbation in the form of strong electron acceptor availability. We find that all three species can co-exist in the absence of sulfate, and that system productivity (in form of methane production from lactate) increases by almost two-fold compared to co-cultures. With increasing sulfate availability, co-existence is perturbed and both methanogenic populations display a diminishing trend. Interestingly, we find that, despite the continued presence of acetate in the system, the acetotrophic methanogens are more readily disrupted by sulfate perturbation. We show that this is due to a shift in M. barkeri metabolism towards increased co-utilisation of hydrogen with acetate, which we verified through experiments on mono cultures and mass balance calculations in co-cultures. We conclude that hydrogen is a key factor for both hydrogeno- and aceto-trophic methanogenesis and can influence these populations differentially under the common ecological perturbation of strong electron acceptor availability. These findings will help engineering of larger synthetic communities for specific applications in biodegradation and understanding complex anaerobic digestion communities found in animal guts, sediments, and bioreactors.