Efficient aerobic fermentation of gluconic acid by high tension oxygen supply strategy with reusable Gluconobacter oxydans HG19 cells.

Abstract

Gluconic acid is a widely used food and beverage additive, but its production suffers from low efficiency and high cost. In this study, a preferable gluconic acid biosynthesis method without repeated seed culture was proposed and developed using the superior performance of Gluconobacter oxydans. A high oxygen atmosphere satisfying the demand of bio-oxidation increased the productivity of gluconic acid up to ~ 32g/L/h and the accumulation up to ~ 420g/L within 24h of fed-batch fermentation. However, the productivity remarkably decreased when the gluconic acid content was over 350g/L. Therefore, a continuous fermentation was designed, which in combination with 5 runs of fed-batch fermentation resulted in the final production of 1700g gluconic acid from 1750g glucose within 60h in a 3L bioreactor. The results suggest that the validity of this model and can enable cost-competitive gluconic acid production in the industry.