A comparative molecular analysis of water-filled limestone sinkholes in north-eastern Mexico

Jason W. Sahl, Marcus O. Gary, J. Kirk Harris, John R. Spear

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


Sistema Zacatón in north-eastern Mexico is host to several deep, water-filled, anoxic, karstic sinkholes (cenotes). These cenotes were explored, mapped, and geochemically and microbiologically sampled by the autonomous underwater vehicle deep phreatic thermal explorer (DEPTHX). The community structure of the filterable fraction of the water column and extensive microbial mats that coat the cenote walls was investigated by comparative analysis of small-subunit (SSU) 16S rRNA gene sequences. Full-length Sanger gene sequence analysis revealed novel microbial diversity that included three putative bacterial candidate phyla and three additional groups that showed high intra-clade distance with poorly characterized bacterial candidate phyla. Limited functional gene sequence analysis in these anoxic environments identified genes associated with methanogenesis, sulfate reduction and anaerobic ammonium oxidation. A directed, barcoded amplicon, multiplex pyrosequencing approach was employed to compare ~100 000 bacterial SSU gene sequences from water column and wall microbial mat samples from five cenotes in Sistema Zacatón. A new, high-resolution sequence distribution profile (SDP) method identified changes in specific phylogenetic types (phylotypes) in microbial mats at varied depths; Mantel tests showed a correlation of the genetic distances between mat communities in two cenotes and the geographic location of each cenote. Community structure profiles from the water column of three neighbouring cenotes showed distinct variation; statistically significant differences in the concentration of geochemical constituents suggest that the variation observed in microbial communities between neighbouring cenotes are due to geochemical variation.

Original languageEnglish (US)
Pages (from-to)226-240
Number of pages15
JournalEnvironmental microbiology
Issue number1
StatePublished - Jan 2011
Externally publishedYes

ASJC Scopus subject areas

  • Microbiology
  • Ecology, Evolution, Behavior and Systematics


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