DMCA
STP Stationary phase (2010)
BibTeX
@MISC{Yilmaz10stpstationary,
author = {Luftu Safak Yilmaz and Wayne S. Kontur and Alison P. S and Ugur Sohmen and Timothy J. Donohue and Daniel R. Noguera and Fum Fumarate and Glc Glucose},
title = {STP Stationary phase},
year = {2010}
}
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Abstract
Abstract The partitioning of reducing power into different electron-accepting pathways was evaluated during growth and stationary phases of H2-producing Rhodobacter sphaeroides cultures. For this, an electron balance method was developed using the chemical oxygen demand concept to quantitatively analyze the partitioning of nutrient electrons into H2, cell biomass, polyhydroxybutyrate (PHB), and soluble microbial products (SMP). Overall, these four electron sinks were accounted for greater than 85 % of the electrons provided by the nutrients. Glucose, lactate, succinate, fumarate, and pyruvate were individually provided as the main carbon source, and in all cases, glutamate was provided as a nitrogen source in order to enhance H2 production. About 25–35 % of the electrons ended up in H2 during growth, while up to 60 % of the electrons partitioned into H2 in some stationary phase cultures. The other two major electron sinks in the growth phase were cell mass and PHB, while in stationary phase, SMP were accounted for>30 % of the substrate electrons utilized. In general, the largest portion of SMP comprised low-molecular weight (<3 kDa) compounds mostly pro-duced during stationary phase, although larger-size mole-cules were also detected in both phases. Overall, the fractions of electrons that partitioned into H2 (0.21 to 0.35) and PHB (0.06 to 0.21) were highly correlated with the standard free energy change of the substrate oxidation half-reaction equation, normalized per electron equivalent. In a PHB(−) mutant, electron redistribution increased H2 production, the extent of which depended on the carbon source provided.
Keyphrases
stp stationary phase stationary phase h2 production standard free energy change low-molecular weight main carbon source cell biomass chemical oxygen demand concept cell mass electron sink soluble microbial product electron balance method nutrient electron substrate oxidation half-reaction equation major electron sink different electron-accepting pathway growth phase nitrogen source h2-producing rhodobacter carbon source electron redistribution electron equivalent substrate electron larger-size mole-cules stationary phase culture
