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Open Access Original article

Evaluation of the food grade expression systems NICE and pSIP for the production of 2,5-diketo-D-gluconic acid reductase from Corynebacterium glutamicum

Vanja Kaswurm1*, Tien-Thanh Nguyen12, Thomas Maischberger1, Klaus D Kulbe1 and Herbert Michlmayr1

Author Affiliations

1 Food Biotechnology Laboratory, Department of Food Science and Technology, BOKU – University of Natural Resources and Life Sciences, Muthgasse 18, Vienna, 1190, Austria

2 School of Biotechnology and Food Technology, Hanoi University of Science and Technology (HUST), Hanoi, Vietnam

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AMB Express 2013, 3:7  doi:10.1186/2191-0855-3-7

Published: 28 January 2013

Abstract

2,5-diketo-D-gluconic acid reductase (2,5-DKG reductase) catalyses the reduction of 2,5-diketo-D-gluconic acid (2,5-DKG) to 2-keto-L-gulonic acid (2-KLG), a direct precursor (lactone) of L-ascorbic acid (vitamin C). This reaction is an essential step in the biocatalytic production of the food supplement vitamin C from D-glucose or D-gluconic acid. As 2,5-DKG reductase is usually produced recombinantly, it is of interest to establish an efficient process for 2,5-DKG reductase production that also satisfies food safety requirements. In the present study, three recently described food grade variants of the Lactobacillales based expression systems pSIP (Lactobacillus plantarum) and NICE (Lactococcus lactis) were evaluated with regard to their effictiveness to produce 2,5-DKG reductase from Corynebacterium glutamicum. Our results indicate that both systems are suitable for 2,5-DKG reductase expression. Maximum production yields were obtained with Lb. plantarum/pSIP609 by pH control at 6.5. With 262 U per litre of broth, this represents the highest heterologous expression level so far reported for 2,5-DKG reductase from C. glutamicum. Accordingly, Lb. plantarum/pSIP609 might be an interesting alternative to Escherichia coli expression systems for industrial 2,5-DKG reductase production.

Keywords:
Ascorbic acid; 2,5-diketo-D-gluconic acid reductase; 2-keto-L-gulonic acid; Corynebacterium glutamicum; Food–grade; Lactic acid bacteria; pSIP; NICE