Microorganisms may reciprocally select for specific interacting partners, forming a network with interdependent relationships. The methanotrophic interaction network, comprising methanotrophs and non-methanotrophs, is thought to modulate methane oxidation and give rise to emergent properties beneficial for the methanotrophs. Therefore, microbial interaction may become relevant for community functioning under stress. However, empirical validation of the role and stressor-induced response of the interaction network remains scarce. Here, we determined the response of a complex methane-driven interaction network to a stepwise increase in NH₄Cl-induced stress (0.5–4.75 g L⁻¹, in 0.25–0.5 g L⁻¹ increments) using enrichment of a naturally occurring complex community derived from a paddy soil in laboratory-scale incubations. Although ammonium and intermediates of ammonium oxidation are known to inhibit methane oxidation, methanotrophic activity was unexpectedly detected even in incubations with high ammonium levels, albeit rates were significantly reduced. Sequencing analysis of the 16S rRNA and pmoA genes consistently revealed divergent communities in the reference and stressed incubations. The 16S rRNA-based co-occurrence network analysis revealed that NH₄Cl-induced stress intensification resulted in a less complex and modular network, likely driven by less stable interaction. Interestingly, the non-methanotrophs formed the key nodes, and appear to be relevant members of the community. Overall, stressor intensification unravels the interaction network, with adverse consequences for community functioning.

中文翻译：

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甲烷驱动的相互作用网络对应激源强化的响应。

微生物可以相互选择特定的相互作用伙伴，从而形成具有相互依存关系的网络。包括甲烷营养菌和非甲烷营养菌的甲烷营养菌相互作用网络被认为可调节甲烷氧化并产生对甲烷营养菌有益的新兴性质。因此，微生物相互作用可能与压力下的社区功能有关。但是，对相互作用网络的作用和压力源性反应的经验验证仍然很少。在这里，我们确定了复杂的甲烷驱动的相互作用网络对NH ₄ Cl诱导的应力逐步增加的响应（0.5–4.75 g L ^-1，在0.25–0.5 g L ^-1中在实验室规模的孵化中，使用源自稻田的天然复杂群落的富集。尽管已知铵和铵氧化的中间体会抑制甲烷氧化，但即使在高铵水平的温育条件下，也无法检测到甲烷营养活性，尽管速率显着降低。对16S rRNA和pmoA基因的测序分析一致地揭示了参考中的不同群落并强调了孵育。基于16S rRNA的共现网络分析显示NH ₄Cl诱导的应力增强导致不太复杂和模块化的网络，可能是由不太稳定的交互作用驱动的。有趣的是，非甲烷营养生物形成了关键节点，并且似乎是社区的相关成员。总体而言，压力源激化会破坏互动网络，对社区功能产生不利影响。