# Genome‐Resolved Approach of Guerrero Negro Hypersaline Microbial Mats Reveals the Metabolic Potential of Key Players in a Stratified Community

## TL;DR

This study uses genome data to uncover the metabolic roles of microbes in hypersaline mats, revealing how different species contribute to carbon, sulfur, and nitrogen cycles.

## Contribution

The first genome-resolved analysis of Guerrero Negro microbial mats, linking microbial identity to metabolic processes in a stratified community.

## Key findings

- Phototrophic taxa are the main source of organic matter in environmental samples.
- Sulfur species act as electron acceptors in the metabolism of partially degraded organic matter in lower mat layers.
- MAGs' metabolic potential aligns with their vertical distribution in the microbial mat.

## Abstract

Hypersaline microbial mats at Guerrero Negro harbor a stratified, highly diverse community with diel metabolic changes. While oxygenic photosynthesis and sulfate reduction are the dominant bacterial metabolic processes, methylotrophic methanogenesis is the main archaeal pathway. Although these metabolic processes have been biochemically characterized, the identity and encoded metabolism of the microorganisms have been inferred only from gene‐marker data. Here, a genome‐resolved approach in both environmental, as well as experimental dark condition samples (control, H2/CO2, TMA, and H2/CO2‐TMA) was used to stimulate less‐known anaerobic strategies, determine the metabolic potential of the main microbial players, and analyze the community. Representative metagenome‐assembled genomes (170 MAGs) were obtained, encompassing 25 bacterial and 4 archaeal phyla. The metabolic analyses of three basic elements (carbon, sulfur, nitrogen) encoded in the MAGs suggested that in environmental samples, phototrophic taxa were the main source of the organic matter that fueled most of the community. Different sulfur species acting as electron acceptors led to the metabolism of partially degraded organic matter in the lower layers of the mat. These results link and clarify the biochemical processes and microbial players, adding a novel genomic component for the ecological understanding of the microbial mats of Guerrero Negro.

The first metagenome‐assembled genomes (MAGs) from Guerrero Negro hypersaline microbial mats were recovered from natural and incubated samples. These MAGs include dominant and rare taxa, whose metabolic potential provides clues to metabolic versatility in the cycling of three elements (carbon, sulfur, and nitrogen) at the genome and community levels. The MAGs' metabolic potential is consistent with their natural vertical distribution.