Medium-reductant directed expression of methyl coenzymeM reductase isoenzymes in Methanobacterium thermoautotrophicum (strain ΔH)

AbstractMethanobacterium thermoautotrophicum was grown in a chemostat under various controlled conditions in the presence of either sodium sulfide or sodium thiosulfate. After establishment of the steady state, cells were taken and examined for expression of the mRNA transcripts coding for the different forms of methyl coenzymeM reductase (MCR) and methylene tetrahydomethanopterin dehydrogenase (MDH). MCR isoenzymeII expression varied most markedly. Expression was found not only to depend on known parameters temperature, pH and gassing rate, but also on the medium composition, especially the reductant present