title: Effect of hydrogen and carbon dioxide partial pressures on growth and sulfide production of the extremely thermophilic archaebacterium Pyrodictium brockii.
abstract: The effect of hydrogen and carbon dioxide partial pressure on the growth of the extremely thermophilic archaebacterium Pyrodictium brockii at 98 degrees C was investigated. Previous work with this bacterium has been done using an 80:20 hydrogen-carbon dioxide gas phase with a total pressure of 4 atm; no attempt has been made to determine if this mixture is optimal. It was found in this study that reduced hydrogen partial pressures affected cell yield, growth rate, and sulfide production. The effect of hydrogen partial pressure on cell yield and growth rate was less dramatic when compared to the effect on sulfide production, which was not found to be growth-associated. Carbon dioxide was also found to affect growth but only at very low partial pressures. The relationship between growth rate and substrate concentration could be correlated with a Monod-type expression for either carbon dioxide or hydrogen as the limiting substrate. The results from this study indicate that a balance must be struck between cell yields and sulfide production in choosing an optimal hydrogen partial pressure for the growth of P. brockii.
authors.affiliation: Department of Chemical Engineering, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
authors.forename: A K
authors.initials: AK
authors.lastname: Parameswaran
authors.forename: R N
authors.initials: RN
authors.lastname: Schicho
authors.forename: J P
authors.initials: JP
authors.lastname: Soisson
authors.forename: R M
authors.initials: RM
authors.lastname: Kelly