Glutathione enhances 2-keto-l-gulonic acid production based on Ketogulonicigenium vulgare model iWZ663

► Prediction of sulfate metabolism deficiency in iWZ663 was confirmed by experiments in a defined medium. ► CoA was proved to be a critical factor for cell growth and 2-KLG production of K. vulgare. ► GSH enhanced 2-KLG productivity by 20.9% in a 7-L fermenter.