The membrane potential in whole cells of Methanobacterium thermoautotrophicum |
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Authors: | Bertram Michael Butsch Reinhard Bachofen |
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Institution: | (1) Institute of Plant Biology, University of Zürich, Zollikerstr. 107, CH-8008 Zürich, Switzerland |
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Abstract: | of whole cells of Methanobacterium thermoautotrophicum was estimated under varying conditions using an electrode sensitive to the lipophilic cation tetraphenylphosphonium chloride (TPP+). Since was found to be extremely sensitive to air, a special reaction vessel was developed to maintain strict anaerobiosis. The cells took up TPP+ under energization by H2 and CO2 thus allowing to calculate the from the distribution of TPP+ inside and outside the cells. The unspecific uptake of deenergized cells was around 10% of the total uptake of energized cells. TPP+ itself slightly diminished the , but had no effect on the formation of methane. Typical values of were in the range of-150 to-200 mV. showed a quantitative dependence on both the electron donor H2 and the electron acceptor CO2. NaCl stimulated the extent of the , whereas KCl slightly diminished it. Valinomycin resulted in a linear decline of , whereas the methane production rate was only slightly affected. In contrast, monensin reduced both methanogenesis and .Abbreviations pmf
proton motive force
-
membrane potential
- TPP+
tetraphenylphosphonium (chloride salt)
- TPMP+
triphenylmethylphosphonium (chloride salt, if not otherwise indicated)
- d.w.
dry weight
-
t
d
doubling time
- PVC
polyvinylchloride |
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Keywords: | Methanobacterium thermoautotrophicum Membrane potential Tetraphenylphosphonium Methanogenesis Electron transport |
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