Environmental stress destabilizes microbial networks

Authors: HERNANDEZ, DAMIAN - University Of Miami; David, Aaron; MENGES, ERIC - Archbold Biological Station; SEARCY, CHRISTOPHER - University Of Miami; AFKHAMI, MICHELLE - University Of Miami

Submitted to: The ISME Journal: Multidisciplinary Journal of Microbial Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/9/2020
Publication Date: 1/15/2021
Citation: Hernandez, D., David, A.S., Menges, E., Searcy, C., Afkhami, M. 2021. Environmental stress destabilizes microbial networks. The ISME Journal: Multidisciplinary Journal of Microbial Ecology. 15:1722–1734. https://doi.org/10.1038/s41396-020-00882-x.
DOI: https://doi.org/10.1038/s41396-020-00882-x

Interpretive Summary: The Stress Gradient Hypothesis (SGH), which predicts that stress increases the prevalence of facilitative interactions compared to competitive ones, could inform how stress shapes microbial interactions with consequences for composition, function, and distribution of microbial communities. Here, we conduct the first test of the SGH in microbial communities by combining a new network analysis tool, “cohesion”, and microbiome sequencing of >40 replicated stress gradients in the Florida Scrub. Our analyses demonstrate that soil microbiomes do follow the predictions of the SGH. Our results support the SGH as a conceptual framework for understanding mechanisms underlying microbial interactions and cohesion analysis as a key part of a future multifaceted, integrative approach to understand interactions in microbial communities.

Technical Abstract: With heightened environmental stress in the Anthropocene, it is crucial to understand how stress impacts species interactions underpinning community structure and ecosystem functions. The Stress Gradient Hypothesis (SGH), which predicts that stress increases the prevalence of facilitative interactions compared to competitive ones, could inform how stress shapes microbial interactions with consequences for composition, function, and distribution of microbial communities. Currently, the SGH is untested in microbiomes due to challenges assessing millions of microscopic interactions. Here, we conduct the first test of the SGH in microbial communities by combining a new network analysis tool, “cohesion”, and microbiome sequencing of >40 replicated stress gradients in the Florida Scrub. We find a positive relationship between stress and the ratio of putative facilitative to negative interactions, supporting microbial adherence to the SGH in this ecosystem. Specifically, the stress/facilitation relationship is unimodal with positive:negative cohesion increasing monotonically until decreasing in the most stressful habitat. Our results support the SGH as a conceptual framework for understanding mechanisms underlying microbial interactions and cohesion analysis as a key part of a future multifaceted, integrative approach to understand interactions in microbial communities.