BACKGROUND: As both S-adenosylmethionine (SAM) and glutathione (GSH) are biosynthesized with ATP consumption in yeast cells, their efficient co-production not only depends on high activities of key enzymes, but also on sufficient energy supply. In this study, dissolved oxygen (DO) was optimized to improve enzyme activity and energy supply for high co-production of SAM and GSH. RESULTS: Batch culture of Candida utilis CCTCC M 209298 under different DO control modes was carried out in a 5 L stirred fermentor. Based on the analyses of kinetic parameters and metabolic fluxes of key nodes involved in the metabolism of SAM and GSH, a two-stage DO control strategy with an initial agitation rate of 350 rpm followed by a constant DO level of 30% was designed for the overproduction of SAM and GSH. A maximum co-production of SAM and GSH of 593.9mg L-1 was achieved using the two-stage DO control strategy, which was much higher than that obtained from other DO control modes. CONCLUSION: Physiological mechanism analysis revealed that the improved co-production of SAM and GSHwas closely related to the increase in key enzyme activities and sufficient energy supply under the two-stage DO control strategy. (C) 2017 Society of Chemical Industry