Environmental stress destabilizes microbial networks

Environmental stress is increasing worldwide, yet we lack a clear picture of how stress disrupts the stability of microbial communities and the ecosystem services they provide. Here, we present the first evidence that naturally-occurring microbiomes display network properties characteristic of unstable communities when under persistent stress. By assessing changes in diversity and structure of soil microbiomes along 40 replicate stress gradients (elevation/water availability gradients) in the Florida scrub ecosystem, we show that: (1) prokaryotic and fungal diversity decline in high stress, and (2) two network properties of stable microbial communities-modularity and negative:positive cohesion-have a clear negative relationship with environmental stress, explaining 51-78% of their variation. Interestingly, pathogenic taxa/functional guilds decreased in relative abundance along the stress gradient, while oligotrophs and mutualists increased, suggesting that the shift in negative:positive cohesion could result from decreasing negative:positive biotic interactions consistent with the predictions of the Stress Gradient Hypothesis. Given the crucial role microbiomes play in ecosystem functions, our results suggest that, by limiting the compartmentalization of microbial associations and creating communities dominated by positive associations, increasing stress in the Anthropocene could destabilize microbiomes and undermine their ecosystem services.

Automated summary

Research shows that natural microbiomes under persistent stress exhibit characteristics of instability, with declines in microbial diversity and changes in network properties of stable communities. Pathogenic taxa decrease while oligotrophs and mutualists increase along stress gradients, impacting the negative:positive cohesion and potentially destabilizing microbiomes and their ecosystem services.