Succinate Degradation through the Citric Acid Cycle in Bradyrhizobium japonicum J501 Bacteroids under Low Oxygen Concentrations

Abstract

The succinate metabolizing pathway under low oxygen concentrations in soybean nodule bacteroids was surveyed by pulse-chase experiments using [2, 3-¹⁴C] succinate and by radio-respirometry. Oxidation of exogenous succinate through the complete citric acid cycle was strongly suggested. Amino acid and sugar formations from exogenous succinate were also observed in the bacteroids. Addition of succinate to the bacteroids increased both the NAD⁺/NADH ratio from 1.8 to 3.0 and the adenylate energy value from 0.25 to 0.53.