Improved co-production of S-adenosylmethionine and glutathione using citrate as an auxiliary energy substrate

The effects of sodium citrate on the fermentative co-production of S-adenosylmethionine (SAM) and glutathione (GSH) using Candida utilis CCTCC M 209298 were investigated. Sodium citrate was beneficial for the biosynthesis of SAM and GSH and in turn improved intracellular SAM and GSH contents. Adding 2 g/L of sodium citrate at 15 h was the most efficient approach for achieving elevated co-production of SAM and GSH. Using this sodium citrate addition mode, co-production of SAM and GSH reached 663.9 mg/L, which was increased by 27.5% compared to the control. Based on analysis of the kinetic parameters, evaluation of the energy metabolism and assay of key enzymes, sodium citrate was verified to act as an auxiliary energy substrate for the overproduction of SAM and GSH.