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Antarctica · Microbial mats · Microbial diversity · 16S rRNA genes · James Ross Archipelago
Abstract:
The James Ross archipelago houses numerous lakes and ponds. In this region, a vast diatom and cyanobacterial variety has
been reported; however, the prokaryotic diversity in microbial mats from these lakes remains poorly explored. Here, a high-
throughput sequencing of 16S rRNA gene in microbial mats from Lake Bart-Roja in James Ross Island and lakes Pan Negro
and North Pan Negro located in Vega Island was performed. Combined with mineralogical and environmental characteristics,
we analyzed the diversity and structure of the microbial communities. Sequences assigned to Archaea were extremely low,
while Bacteria domain prevailed with the abundance of Proteobacteria (mostly Betaproteobacteriales) followed by Bacte-
roidetes, Verrucomicrobia, Firmicutes, and Cyanobacteria. Local environmental conditions, such as conductivity and Eh,
provided differential microbial assemblages that might have implications in the oligotrophic status of the lakes. Consequently,
a clear segregation at the family level was observed. In this sense, the assigned diversity was related to taxa recognized as
denitrifiers and sulfur oxidizers. Particularly, in Lake Pan Negro sulfur-reducing and methanogenic representatives were
also found and positively correlate with alkalinity and water depth. Moreover, Deinococcus-Thermus was observed in Lake
Bart-Roja, while Melainabacteria (Cyanobacteria)—poorly reported in Antarctic mats—was detected in Lake Pan Negro.
Epsilonbacteraeota was exclusively found in this lake, suggesting new potential phylotypes. This study contributes to the
understanding of the diversity, composition, and structure of Antarctic benthic microbial ecosystems and provides highly
valuable information, which can be used as a proxy to evaluate environmental changes affecting Antarctic microbiota.
