biostudies-literatureSolomon RIsraeli Dairy BoardIsrael Science FoundationIsrael Science Foundation (ISF)Israeli Dairy Board (Israel Dairy Board)1187-1197https://www.ebi.ac.uk/biostudies/studies/S-EPMC8941083biostudies-literatureUnknown16(4)Unicellular eukaryotes are an integral part of many microbial ecosystems where they interact with their surrounding prokaryotic community-either as predators or as mutualists. Within the rumen, one of the most complex host-associated microbial habitats, ciliate protozoa represent the main micro-eukaryotes, accounting for up to 50% of the microbial biomass. Nonetheless, the extent of the ecological effect of protozoa on the microbial community and on the rumen metabolic output remains largely understudied. To assess the role of protozoa on the rumen ecosystem, we established an in-vitro system in which distinct protozoa sub-communities were introduced to the native rumen prokaryotic community. We show that the different protozoa communities exert a strong and differential impact on the compThe ISME journalProtozoa populations are ecosystem engineers that shape prokaryotic community structure and function of the rumen microbial ecosystem.PMC8941083603/20362-0524/25Wein TDror RFurman OEshed SJami ELevy BReiss VSolomon RZehavi TMizrahi IfalseProtozoa populations are ecosystem engineers that shape prokaryotic community structure and function of the rumen microbial ecosystem.Unicellular eukaryotes are an integral part of many microbial ecosystems where they interact with their surrounding prokaryotic community-either as predators or as mutualists. Within the rumen, one of the most complex host-associated microbial habitats, ciliate protozoa represent the main micro-eukaryotes, accounting for up to 50% of the microbial biomass. Nonetheless, the extent of the ecological effect of protozoa on the microbial community and on the rumen metabolic output remains largely understudied. To assess the role of protozoa on the rumen ecosystem, we established an in-vitro system in which distinct protozoa sub-communities were introduced to the native rumen prokaryotic community. We show that the different protozoa communities exert a strong and differential impact on the comp2022-01-01T00:00:00Z2022 Apr2025-04-05T15:52:59.102Z2025-04-05T15:52:59.102ZS-EPMC89410833488754910.1038/s41396-021-01170-y