Growth kinetics and energetics of a deep-sea hyperthermophilic methanogen under varying environmental conditions Journal Article


Authors: Ver Eecke, Helene C.; Akerman, Nancy H.; Huber, Julie A.; Butterfield, David A.; Holden, James F.
Article Title: Growth kinetics and energetics of a deep-sea hyperthermophilic methanogen under varying environmental conditions
Abstract: A hyperthermophilic deep-sea methanogen, Methanocaldococcus strain JH146, was isolated from 26 degrees C hydrothermal fluid at Axial Volcano 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 CO2 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 1.69x10(-11) J cell(-1)s(-1)+/- 0.68x10(-11) J cell(-1)s(-1) (s.d., n=23). An exception was at superoptimal growth temperatures where GE increased to 7.25x10(-11) J cell(-1)s(-1) presumably due to heat shock. GE also increased from 5.1x10(-12) J cell(-1)s(-1) to 7.61x10(-11) J cell(-1)s(-1) as NH4+ concentrations decreased from 9.4mM to 0.14mM. JH146 did not fix N-2 or assimilate NO3-, lacked the N-2-fixing (cluster II) nifH gene, and became nitrogen limited below 0.14mM NH4Cl. Nitrogen availability may impact growth in situ since ammonia concentrations at Axial Volcano are lt;18M. Our approach contributes to refining bioenergetic and carbon flux models for methanogens and other organisms in hydrothermal vents and other environments.
Keywords: DIVERSITY; IDENTIFICATION; HYDROTHERMAL VENT; RIDGE; BIOSPHERE; SYSTEMS; SUBSURFACE; SP. NOV.; ENERGY-REQUIREMENTS; ARCHAEON
Journal Title: Environmental Microbiology Reports
Volume: 5
Issue: 5
ISSN: 1758-2229
Publisher: Blackwell Publishing  
Publication Place: HOBOKEN; 111 RIVER ST, HOBOKEN 07030-5774, NJ USA
Date Published: 2013
Start Page: 665
End Page: 671
DOI/URL:
Notes: PT: J; TC: 0; UT: WOS:000325142700005