Activity and Distribution of Thermophilic Prokaryotes in Hydrothermal Fluid Sulfidic Structures and Sheaths of Alvinellids (East Pacific Rise 13°N)

摘要

Processes of inorganic carbon assimilation, methanogenesis, sulfate reduction, and acetate oxidation to CO2 occurring in samples from the East Pacific Rise at 13°N were traced, using radioisotopically labeled substrates, at temperatures ranging from 65 to 100°C. Molecular hydrogen stimulated lithotrophic methanogenesis and sulfate reduction but inhibited inorganic carbon assimilation. Active mineralization of acetate was observed in an organic-rich Alvinella-associated system at 80°C. Members of the Thermococcales were the most numerous hyperthermophilic archaea in these samples, their density achieving 10⁸ cells per cm³, while the numbers of cultured hydrogen-utilizing thermophilic lithotrophs were several orders of magnitude lower.