Thermophilic Archaeal Diversity and Methanogenesis from El Tatio Geyser Field, Chile

ABSTRACT

The hydrothermal fluid chemistry at El Tatio Geyser Field (ETGF) in northern Chile suggests that biogenic CO₂–CH₄ cycling may play an important role in water chemistry, and relatively low sulfate (0.6–1 mM) and high molecular hydrogen (H₂) concentrations (67–363 nM) suggest that methanogenic Archaea are present in ETGF microbial mats. In this study, δ¹³C analysis of dissolved inorganic carbon and methane was not indicative of biogenic methane production (δ¹³C_CH4 values ranging from −15‰ to −5.3‰); however, methanogenic Archaea were successfully cultured from each of the hydrothermal sites sampled. Sanger sequencing using universal Archaea primers identified putative methanogenic orders with varying metabolic capabilities, including Methanobacteriales, Methanomicrobiales and Methanosarcinales.

KEYWORDS:

• Archaea
• community structure
• methanogenesis

Acknowledgments

We are extremely grateful for field and laboratory support from Jeff Landrum, Jay Santillan, Kim Myers, Reed Malin and Suzanne Pierce. We also thank the anonymous reviewers for their valuable comments.

Funding

This work was generously funded by the National Science Foundation (EAR-0544960 and EAR-0545336) from 2006-2009, and by the Jackson School of Geosciences at The University of Texas at Austin.