Industrial Fermentation of Vitamin C

Abstract

L-ascorbic acid (vitamin C), which was first isolated in 1928, is an essential nutrient for humans and a few other mammals. Vitamin C is widely used in the food, beverage, animal feed and pharmaceutical industries. Reichstein–Grüssner process was first designed for vitamin C production on industrial scale in 1933. D-sorbitol is converted to L-ascorbic acid using a fermentation step (Bioconversion of D-sorbitol to L-sorbose by Gluconobacter oxydans) and several chemical steps (from L-sorbose to L-ascorbic acid). Today, a two-step fermentation process is widely used by Chinese manufacturers for vitamin C production due to low cost and high product quality. When compared with the classical process, a mixed fermentation consisting of Ketogulonicigenium vulgare and Bacillus spp. is conducted to convert L-sorbose to the intermediate 2-keto-L-gulonic acid (2-KLG) in the two-step fermentation process. Many efforts, such as strains improvements, metabolic regulation and fermentation process optimisation, have been made to improve the fermentation efficiency for 2-KLG production. Finally, perspectives on improving the fermentation efficiency for the industrial production of vitamin C are discussed.