# What defines a photosynthetic microbial mat in western Antarctica?

## TL;DR

This study explores the composition and characteristics of photosynthetic microbial mats in western Antarctica, revealing consistent bacterial communities and the role of diatoms in distinguishing different regions.

## Contribution

The study provides a detailed metagenomic analysis of Antarctic microbial mats, identifying key bacterial and eukaryotic components and their functional roles.

## Key findings

- Bacteria dominate Antarctic microbial mats, with Bacteroidota and Pseudomonadota being the most abundant phyla.
- Diatoms are a distinguishing factor between rapidly warming Maritime Antarctica and other regions.
- All mats showed nitrogen limitation and shared functional patterns despite varying environmental conditions.

## Abstract

Antarctic microbial mats, with their significant biodiversity and key role in biogeochemical cycling, were the focus of our study. We employed a metagenomic approach to analyze 14 microbial mats from meltwater streams of western Antarctica, covering the Maritime, Peninsula, and Dry Valleys regions. Our findings revealed that the taxonomic compositional level of the microbial mat communities is characterized by similar bacterial groups, with diatoms being the main distinguishing factor between the rapidly warming Maritime Antarctica and the other mats. Bacteria were found to be the predominant component of all microbial mats (>90%), followed by Eukarya (>3%), Archaea (<1%), and Viruses (<0.1%). The average abundance of the main phyla composing Antarctic microbial mats included Bacteroidota (35%), Pseudomonadota (29%), Cyanobacteriota (19%), Verrucomicrobiota (3%), Bacillariophyta (2%), Planctomycetota (2%), Acidobacteriota (2%), Actinomycetota (2%), Bacillota (1%), and Chloroflexota (1%). We also identified some microeukaryotes that could play essential roles in the functioning of Antarctic microbial mats. Notably, all mats were found in sites with varied environmental characteristics, showed N-limitation, and shared functional patterns.