Helmholtz Centre for Environmental Research-UFZ, Department of Environmental Microbiology, Permoserstraße 15, 04318, Leipzig, Germany.
School of Engineering, Environmental Engineering, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
Environ Microbiol. 2019 Jan;21(1):164-181. doi: 10.1111/1462-2920.14437. Epub 2018 Nov 8.
In completely insular microbial communities, evolution of community structure cannot be shaped by the immigration of new members. In addition, when those communities are run in steady state, the influence of environmental factors on their assembly is reduced. Therefore, one would expect similar community structures under steady-state conditions. Yet, in parallel setups, variability does occur. To reveal ecological mechanisms behind this phenomenon, five parallel reactors were studied at the single-cell level for about 100 generations and community structure variations were quantified by ecological measures. Whether community variability can be controlled was tested by implementing soft temperature stressors as potential synchronizers. The low slope of the lognormal rank-order abundance curves indicated a predominance of neutral mechanisms, i.e., where species identity plays no role. Variations in abundance ranks of subcommunities and increase in inter-community pairwise β-diversity over time support this. Niche differentiation was also observed, as indicated by steeper geometric-like rank-order abundance curves and increased numbers of correlations between abiotic and biotic parameters during initial adaptation and after disturbances. Still, neutral forces dominated community assembly. Our findings suggest that complex microbial communities in insular steady-state environments can be difficult to synchronize and maintained in their original or desired structure, as they are non-equilibrium systems.
在完全孤立的微生物群落中，群落结构的进化不能通过新成员的迁入来塑造。此外，当这些群落处于稳定状态时，环境因素对它们组装的影响会降低。因此，人们预计在稳定状态下会出现相似的群落结构。然而，在平行设置中，确实会发生可变性。为了揭示这种现象背后的生态机制，在单细胞水平上对五个平行的反应器进行了大约 100 代的研究，并通过生态措施量化了群落结构的变化。通过实施软性温度胁迫作为潜在的同步因子来测试群落可变性是否可以得到控制。对数正态等级丰度曲线的低斜率表明主要是中性机制，即物种身份不起作用。亚群落丰度等级的变化和群落间成对β多样性的增加随时间的推移支持了这一点。还观察到了生态位分化，这表明在初始适应和干扰后，等级状丰度曲线变得更加陡峭，生物和非生物参数之间的相关性增加。尽管如此，中性力量还是主导了群落组装。我们的研究结果表明，在孤立的稳定环境中，复杂的微生物群落可能难以同步，也难以保持其原始或期望的结构，因为它们是非平衡系统。
