Discovery and Description of Giant Submarine Smectite Cones on the Seafloor in Eyjafjordur, Northern Iceland, and a Novel Thermal Microbial Habitat

• Published in: Applied and Environmental Microbiology
• Main Authors: Marteinsson, Viggó Thór, Kristjánsson, Jakob K., Kristmannsdóttir, Hrefna, Dahlkvist, Maria, Sæmundsson, Kristján, Hannington, Mark, Pétursdóttir, Sólveig K., Geptner, Alfred, Stoffers, Peter
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Society for Microbiology 2001
• Subjects: The Cones; Iceland
• Online Access: http://dx.doi.org/10.1128/aem.67.2.827-833.2001; https://journals.asm.org/doi/pdf/10.1128/AEM.67.2.827-833.2001

ABSTRACT With the submersible JAGO and by scuba diving we discovered three remarkable geothermal cones, rising 33, 25, and 45 m from the seafloor at a depth of 65 m in Eyjafjordur, northern Iceland. The greatest geothermal activity was on the highest cone, which discharged up to 50 liters of freshwater per s at 72°C and pH 10.0. The cones were built up from precipitated smectite, formed by mixing of the hot SiO 2 -rich geothermal fluid with the cold Mg-rich seawater. By connecting a rubber hose to one outflow, about 240 liters of pure geothermal fluids was concentrated through a 0.2-μm-pore-size filter. Among 50 thermophilic isolates, we found members of Bacillus and Thermonema and a new unidentified low-G+C gram-positive member of the Bacteria as well as one member of the Archaea , Desulfurococcus mobilis . Analysis of small-subunit rRNA genes PCR amplified and cloned directly from environmental DNA showed that 41 out of 45 Bacteria sequences belonged to members of the Aquificales , whereas all of the 10 Archaea sequences belonged to the Korarchaeota . The physiological characteristics of isolates from different parts of the cones indicate a completely freshwater habitat, supporting the possibility of subterranean transmittance of terrestrial organisms.