Protist communities of microbial mats from the extreme environments of five saline Andean lagoons at high altitudes in the Atacama Desert

Front Microbiol. 2024 Mar 20:15:1356977. doi: 10.3389/fmicb.2024.1356977. eCollection 2024.


Introduction: Heterotrophic protists colonizing microbial mats have received little attention over the last few years, despite their importance in microbial food webs. A significant challenge originates from the fact that many protists remain uncultivable and their functions remain poorly understood.

Methods: Metabarcoding studies of protists in microbial mats across high-altitude lagoons of different salinities (4.3-34 practical salinity units) were carried out to provide insights into their vertical stratification at the millimeter scale. DNA and cDNA were analyzed for selected stations.

Results: Sequence variants classified as the amoeboid rhizarian Rhogostoma and the ciliate Euplotes were found to be common members of the heterotrophic protist communities. They were accompanied by diatoms and kinetoplastids. Correlation analyses point to the salinity of the water column as a main driver influencing the structure of the protist communities at the five studied microbial mats. The active part of the protist communities was detected to be higher at lower salinities (<20 practical salinity units).

Discussion: We found a restricted overlap of the protist community between the different microbial mats indicating the uniqueness of these different aquatic habitats. On the other hand, the dominating genotypes present in metabarcoding were similar and could be isolated and sequenced in comparative studies (Rhogostoma, Euplotes, Neobodo). Our results provide a snapshot of the unculturable protist diversity thriving the benthic zone of five athalossohaline lagoons across the Andean plateau.

Keywords: Euplotes; Rhogostoma; co-occurrence; metabarcoding; microbial mats; protists; salinity.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. The study was carried out in the frame of Collaborative Research Centre 1211 “Evolution at the dry limit”. This study was supported by grants from the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) to HA (project numbers 268236062 (SFB 1211; B03, B02) and to FN (SPP 1991, project NI 1097/4). EA was supported by the German Academic Exchange Service (DAAD) Program Research Scholarships “Promotionen in Deutschland, 2019/20” (57440921).