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Growth kinetics and energetics of a deep‐sea hyperthermophilic methanogen under varying environmental conditions
Author(s) -
Ver Eecke Helene C.,
Akerman Nancy H.,
Huber Julie A.,
Butterfield David A.,
Holden James F.
Publication year - 2013
Publication title -
environmental microbiology reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.229
H-Index - 69
ISSN - 1758-2229
DOI - 10.1111/1758-2229.12065
Subject(s) - methanogen , methanogenesis , energetics , bioenergetics , hydrothermal circulation , kinetics , carbon fibers , hyperthermophile , archaea , nitrogen , biology , hydrothermal vent , flux (metallurgy) , chemistry , environmental chemistry , biophysics , biochemistry , ecology , methane , materials science , gene , paleontology , physics , organic chemistry , quantum mechanics , composite number , mitochondrion , composite material
Summary A hyperthermophilic deep‐sea methanogen, M ethanocaldococcus strain JH 146, was isolated from 26°C hydrothermal fluid at A xial V olcano to model high temperature methanogenesis in the subseafloor. Emphasis was placed on defining growth kinetics, cell yields and growth energy demand ( GE ) across a range of conditions. The organism uses H 2 and CO 2 as its sole carbon and energy sources. At various temperatures, pHs, and chlorinities, its growth rates and cell yields co‐varied while GE remained uniform at 1.69 × 10 −11 J cell −1 s −1 ± 0.68 × 10 −11 J cell −1 s −1 (s.d., n = 23). An exception was at superoptimal growth temperatures where GE increased to 7.25 × 10 −11 J cell −1 s −1 presumably due to heat shock. GE also increased from 5.1 × 10 −12 J cell −1 s −1 to 7.61 × 10 −11 J cell −1 s −1 as NH 4 + concentrations decreased from 9.4 mM to 0.14 mM. JH146 did not fix N 2 or assimilate NO 3 − , lacked the N 2 ‐fixing (cluster II ) nifH gene, and became nitrogen limited below 0.14 mM NH 4 Cl . Nitrogen availability may impact growth in situ since ammonia concentrations at A xial V olcano are < 18 μM. Our approach contributes to refining bioenergetic and carbon flux models for methanogens and other organisms in hydrothermal vents and other environments.