Abstract
Green sulfur bacterium Chlorobium tepidum grows phototrophically using various reduced inorganic sulfur compounds such as sulfide and thiosulfate, as well as hydrogen, as ultimate electron donors. The mechanism of thiosulfate oxidation in the oxidizing side of RC is obscure. In this study, we purified thiosalfate-oxydizing multi enzyme from C. tepidum by ammonium sulfate fractionation, anion-exchange chromatography and cation-exchange chromatography. From N-terminal amino acid sequences of subunits of the purified multi enzyme, it was shown that the genes coding subunits of thiosalfate-oxydizing multi enzyme composed a gene cluster in the genome of C. tepidum which is very similar to sox (sulfur oxidation) gene cluster of α-proteobacterium Paracoccus pantotrophus. It is being experimented on whether for the thiosalfate-oxydizing multi enzyme to involve in electron transfer from thiosulfate to RC.
