[Possible pathways for acetyl-CoA formation by purple bacteria].

Purple sulfur (Ectothiorhodospira shaposhnikovii, Chromatium minutissimum, Lamprobacter modestohalophilus, Thiocapsa roseopersicina) and nonsulfur (Rhodospirillum rubrum, Rhodopseudomonas palustris, Rhodopseudomonas spheroides) bacteria are capable of forming acetyl-CoA synthetase, phosphotransacetylase and acetokinase independent of the medium composition and growth conditions. In all of the purple sulfur bacteria with an exception of E. shaposhnikovii, the activity of acetokinase is much higher than in purple nonsulfur bacteria. Apart from being involved in the synthesis of acetyl-CoA, such enzymes as phosphotransacetylase, acetokinase and adenylate kinase may play an important role in energy processes of some purple bacteria in the dark.