@article {1202,
	title = {Growth kinetics and energetics of a deep-sea hyperthermophilic methanogen under varying environmental conditions.},
	journal = {Environ Microbiol Rep},
	volume = {5},
	year = {2013},
	month = {2013 Oct},
	pages = {665-71},
	abstract = {<p>A hyperthermophilic deep-sea methanogen, Methanocaldococcus strain JH146, was isolated from 26{\textdegree}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 H2 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 1.69 {\texttimes} 10(-11) J cell(-1)s(-1) {\textpm} 0.68 {\texttimes} 10(-11) J cell(-1)s(-1) (s.d., n = 23). An exception was at superoptimal growth temperatures where GE increased to 7.25 {\texttimes} 10(-11) J cell(-1)s(-1) presumably due to heat shock. GE also increased from 5.1 {\texttimes} 10(-12) J cell(-1)s(-1) to 7.61 {\texttimes} 10(-11) J cell(-1)s(-1) as NH4 (+) concentrations decreased from 9.4 mM to 0.14 mM. JH146 did not fix N2 or assimilate NO3 (-), lacked the N2-fixing (cluster II) nifH gene, and became nitrogen limited below 0.14 mM NH4Cl. Nitrogen availability may impact growth in situ since ammonia concentrations at Axial Volcano are < 18 μM. Our approach contributes to refining bioenergetic and carbon flux models for methanogens and other organisms in hydrothermal vents and other environments.</p>},
	issn = {1758-2229},
	doi = {10.1111/1758-2229.12065},
	author = {Ver Eecke, Helene C and Akerman, Nancy H and Huber, Julie A and Butterfield, David A and Holden, James F}
}
