Propionate formation in Rhodospirillum rubrum under anaerobic dark conditions

✍ Scribed by H. Voelskow; Prof. Dr. G. Schön

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 618 KB
• Volume: 21
• Category: Article
• ISSN: 0233-111X
• DOI: 10.1002/jobm.19810210708

✦ Synopsis

Abstract

Experiments with ^14^C labelled propionyl‐CoA, methylmalonyl‐CoA and succinyl‐CoA showed that these compounds are intermediates of propionate synthesis in fermentative metabolism of Rhodospirillum rubrum. The rate of propionate and succinate production is dependent on the CO~2~ concentration of the medium. There is, however, no evidence for a transcarboxylation, and high concentrations of propionate in the medium did not inhibit propionate synthesis as is the case in propionibacteria. PEP‐carboxykinase (EC 4.1.1.32) and propionyl‐CoA‐carboxylase (EC 6.4.1.3) showed high activities, whereas the other two PEP‐carboxylases (EC 4.1.1.31, EC 4.1.1.38), and the pyruvate‐carboxylase (EC 4.1.1.1.) showed only very low activity. It is probable that in pyruvate fermentation metabolism of R. rubrum no specific enzymes are activated for propionate formation and all enzymes are still present from aerobic or phototrophic preculture.