Host identity is the dominant factor in the assembly of nematode and tardigrade gut microbiomes in Antarctic Dry Valley streams

• Published in: Scientific Reports
• Main Authors: J. Parr McQueen, Kaitlin Gattoni, Eli M. S. Gendron, Steven K. Schmidt, Pacifica Sommers, Dorota L. Porazinska
• Format: Article in Journal/Newspaper
• Language: English
• Published: Nature Portfolio 2022
• Subjects: Medicine; R; Science; Q; Antarctic; Antarc*; antarcticus; Eudorylaimus antarcticus; Tardigrade
• Online Access: https://doi.org/10.1038/s41598-022-24206-5; https://doaj.org/article/0dcd1c5363794a77879d1d302178232b

Abstract Recent work examining nematode and tardigrade gut microbiomes has identified species-specific relationships between host and gut community composition. However, only a handful of species from either phylum have been examined. How microbiomes differ among species and what factors contribute to their assembly remains unexplored. Cyanobacterial mats within Antarctic Dry Valley streams host a simple and tractable natural ecosystem of identifiable microinvertebrates to address these questions. We sampled 2 types of coexisting mats (i.e., black and orange) across four spatially isolated streams, hand-picked single individuals of two nematode species (i.e., Eudorylaimus antarcticus and Plectus murrayi) and tardigrades, to examine their gut microbiomes using 16S and 18S rRNA metabarcoding. All gut microbiomes (bacterial and eukaryotic) were significantly less diverse than the mats they were isolated from. In contrast to mats, microinvertebrates’ guts were depleted of Cyanobacteria and differentially enriched in taxa of Bacteroidetes, Proteobacteria, and Fungi. Among factors investigated, gut microbiome composition was most influenced by host identity while environmental factors (e.g., mats and streams) were less important. The importance of host identity in predicting gut microbiome composition suggests functional value to the host, similar to other organisms with strong host selected microbiomes.