Microbial diversity and biomarker analysis of modern freshwater microbialites from Laguna Bacalar, Mexico

Laguna Bacalar is a sulfate‐rich freshwater lake on the Yucatan Peninsula that hosts large microbialites. High sulfate concentrations distinguish Laguna Bacalar from other freshwater microbialite sites such as Pavilion Lake and Alchichica, Mexico, as well as from other aqueous features on the Yucata...

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Bibliographic Details
Published in:Geobiology 2018-05, Vol.16 (3), p.319-337
Main Authors: Johnson, D. B., Beddows, P. A., Flynn, T. M., Osburn, M. R.
Format: Article
Language:English
Subjects:
Abundance
Agglomeration
Alphaproteobacteria
Bacteria
BASIC BIOLOGICAL SCIENCES
Biogeochemical cycles
Biogeochemistry
Biomarkers
Carbonates
Cyanobacteria
DNA
DNA sequences
DNA sequencing
Fatty acids
Freshwater
Freshwater lakes
Gammaproteobacteria
GEOSCIENCES
Inland water environment
Laguna Bacalar
lipid biomarkers
Lipids
Mangroves
Microbial activity
microbialites
Microscopy
Phylogenetics
Phylogeny
sulfate reducing bacteria
Sulfates
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Summary:Laguna Bacalar is a sulfate‐rich freshwater lake on the Yucatan Peninsula that hosts large microbialites. High sulfate concentrations distinguish Laguna Bacalar from other freshwater microbialite sites such as Pavilion Lake and Alchichica, Mexico, as well as from other aqueous features on the Yucatan Peninsula. While cyanobacterial populations have been described here previously, this study offers a more complete characterization of the microbial populations and corresponding biogeochemical cycling using a three‐pronged geobiological approach of microscopy, high‐throughput DNA sequencing, and lipid biomarker analyses. We identify and compare diverse microbial communities of Alphaproteobacteria, Deltaproteobacteria, and Gammaproteobacteria that vary with location along a bank‐to‐bank transect across the lake, within microbialites, and within a neighboring mangrove root agglomeration. In particular, sulfate‐reducing bacteria are extremely common and diverse, constituting 7%–19% of phylogenetic diversity within the microbialites, and are hypothesized to significantly influence carbonate precipitation. In contrast, Cyanobacteria account for less than 1% of phylogenetic diversity. The distribution of lipid biomarkers reflects these changes in microbial ecology, providing meaningful biosignatures for the microbes in this system. Polysaturated short‐chain fatty acids characteristic of cyanobacteria account for
ISSN:1472-4677
1472-4669
DOI:10.1111/gbi.12283