A global overview of the trophic structure within microbiomes across ecosystems

• We investigated paired bacteria and protists across ecosystems at the global scale. Predatory dominated in soils, phototrophs aquatic environments. positively correlated with bacterial richness natural soils. Anthropogenic factors might have negative effects on microbiome trophic structures. The colossal project of mapping Earth is rapidly advancing, a focus individual microbial groups. However, assessment associations between predatory their prey still missing cross-ecosystem level. This knowledge critical to better understand importance top-down links structuring microbiomes. Here, we examined 38 sequence-based datasets protistan taxa, covering 3,178 samples from diverse habitats including freshwater, marine show that community profiles strongly within habitats, structures fundamentally differing habitats. Soils hosted most heterogenous Protist communities were by predators soils led changes ratio total richness, which was highest marine, while Taxon relative abundance These differed protist forest grassland but not agricultural Our results suggested anthropogenic pressure affects higher levels more than lower ones leading decoupled structure Together, our cumulative overview patterns scale revealed major differences microbiomes Earth’s Furthermore, increased impact especially suggests often-observed reduced ecosystem functions systems be partly attributed reduction complexity.