A curated database of rumen ciliate protozoal 18S rRNA gene sequences for metataxonomic applications

Objectives Protozoa are key members of the rumen microbiome playing significant roles in nutrient cycling and methane production, yet are understudied. As rumen metataxonomic studies increasingly incorporate protozoal primers, the lack of curated dedicated reference databases limits accurate classification. This dataset was developed to address that gap and support future protozoa-focused rumen microbial analyses. Data description The curated dataset comprises 228 rumen ciliate protozoal 18S rRNA gene sequences sourced from publicly available datasets. Sequences were processed to remove redundancy and standardise naming. The final database spans 23 families, 53 genera, and 100 species, and is suitable for use in metataxonomic pipelines, including QIIME2. It provides a valuable resource for researchers aiming to improve taxonomic resolution of protozoal communities in rumen environments.