ELECTRON-TRANSPORT SYSTEM IN PSEUDOMONAS-HYDROGENOTHERMOPHILA STRAIN TH-1, A THERMOPHILIC HYDROGEN-OXIDIZING BACTERIUM

The electron transport system in Pseudomonas hydrogenothermophila strain TH-1, a thermophilic, aerobic hydrogen-oxidizing bacterium, was studied using a membrane fraction, an ubiquinone-depleted membrane fraction (Q(-) MF), and an ubiqunone-reconstituted membrane fraction (Q(+) MF). From spectrophotometric and TLC analyses, cytochromes b and c, ubiquinone-8 (Q(8)), and cytochrome o were detected as respiratory components in the membrane fraction of P. hydrogenothermophila. Spectrophotometric analyses also showed that reduction of all the components in the membrane fraction depends on a membrane-bound hydrogenase reaction. In Q(-) MF, reduction of cytochromes b and c depending on membrane-bound hydrogenase reaction could not be observed. However, the reduction was restored in Q(+). MF. From these results, a possible electron transport system in P. hydrogenothermophila strain TH-1 is proposed.