Protists show high resilience and thrive under multiple chemical stressors

Abstract

Protists are an underexplored but functionally important component of aerobic-activated granular sludge under pollution stress. Using metagenomics, we profiled protistan responses to ciprofloxacin, triclosan, and Cu²⁺ (alone or in combination). Protists remained a stable 6.35%–7.88% of the bacterial community, and the consumers were the most abundant groups. Ciprofloxacin showed little effect on protist abundance, while Cu²⁺ increased protist abundance, especially consumers. Stress conditions also strengthened predominantly positive protist–bacteria associations, suggesting cross-domain interactions that may enhance community resilience. These results demonstrate that protists are key determinants in stabilizing microbial communities under multiple stressors.

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2026 The Author(s). mLife published by John Wiley & Sons Australia, Ltd on behalf of Institute of Microbiology, Chinese Academy of Sciences.