[Carbonic anhydrase activity of phototropic bacteria]

The activity of carboanhydrase was assayed in seven species of phototrophous bacteria: three species of the Rhodospirillaceae genus, three species of the Chromatiaceae genus, and one species of the Chlorobiaceae genus. The activity of carboanhydrase was found in five species among seven. It decreased on passing from photoautotrophous to photoheterotrophous conditions of growth, and then to dark heterotrophous conditions, which correlated with the activity of the Calvin cycle in the bacteria. No activity of carboanhydrase was detected in Ectothiorhodospira shaposhnikovii and Chlorobium limicola, probably because Chl. limicola fixed carbon dioxide not in the Calvin cycle, but in the reactions of reductive carboxylation of organic acids.