1.
Current challenges facing one-step production of l-ascorbic acid.
Wang, P, Zeng, W, Xu, S, Du, G, Zhou, J, Chen, J
Biotechnology advances. 2018;(7):1882-1899
Abstract
l-ascorbic acid (L-AA, vitamin C) is an essential vitamin that is widely used as a nutrient or medicine in the pharmaceuticals, cosmetics, food, beverage and feed additive industries, and accounts for the largest share of the global vitamins market. L-AA is mainly produced by a classic two-step fermentation process that suffers from the use of a multi-step mixed culture system and two rounds of sterilisation, which significantly increases the cost of the final product. One-step fermentation has been attempted, but a method rivalling the efficiency of the two-step process has not yet been achieved on an industrial scale. In this review, based on the current classical two-step fermentation processes and other potential routes for L-AA production, the challenges and pitfalls of a one-step fermentation process are summarised. The prospects for one-step fermentation production of L-AA and how this might be achieved are also discussed.
2.
Effect of Oral Vitamin C Supplementation on High-Altitude Hyperuricemia in Young Men Initially Migrating to High Altitude: A Pilot Study.
Peng, H, Feng, D, Wang, Y, Dong, Z, Chen, Q, Zhang, L, Luo, R, Chen, J, Wang, A, Ma, S
High altitude medicine & biology. 2018;(4):373-381
Abstract
OBJECTIVE Clinical studies have shown that oral vitamin C supplementation can reduce serum uric acid levels in multiple populations and may also improve acute mountain sickness. However, it is unclear whether this protocol can improve high-altitude hyperuricemia. Therefore, we aimed to evaluate the role of vitamin C supplementation on high-altitude hyperuricemia. METHODS A preliminary prospective control study was performed in 2015. Young male army recruits (n = 66), who had recently arrived on the Tibetan Plateau for the first time, were recruited for study I. Subjects were assigned to either the vitamin C group, who took an oral daily dose of 500 mg vitamin C for 1 month, or the blank control group, who had no intervention. The levels of serum uric acid, serum creatinine, and blood urea nitrogen were monitored at baseline and at the end of 1 month. In a second study II in 2016 (n = 120), the effect of 500 mg/d vitamin C on high-altitude hyperuricemia was compared with 75 IU/d of vitamin E. RESULTS In study I, the level of serum uric acid at 1 month was significantly higher than at baseline (436.1 ± 79.3 μmol/L vs. 358.0 ± 79.8 μmol/L, p < 0.001) and the prevalence of hyperuricemia was also significantly higher (63.6% [95% confidence interval, CI: 52.0%-75.2%] vs. 19.7% [95% CI: 10.1%-29.3%], p < 0.001). Both the level of serum uric acid (411.5 ± 74.2 μmol/L vs. 460.8 ± 54.8 μmol/L, p = 0.003) and the prevalence of hyperuricemia (48.5% [95% CI: 31.4%-65.6%] vs. 78.8% [95% CI: 64.9%-92.7%], p = 0.020) were significantly lower in the vitamin C group than in the blank control group. In study II, the levels of serum uric acid and the frequency of hyperuricemia also increased over 1 month and were similar in the vitamin C and the vitamin E groups at both baseline and 1 month (p > 0.05). The change in serum uric acid was positively correlated with both the changes in serum creatinine (r = 0.599, p < 0.001) and blood urea nitrogen (r = 0.207, p = 0.005). CONCLUSIONS These findings indicate that healthy young men develop an increase in serum uric acid within a month of moving from low to high altitude. Oral vitamin C supplementation can safely reduce this increase at a low cost.
3.
Structure, mechanism and regulation of an artificial microbial ecosystem for vitamin C production.
Zou, W, Liu, L, Chen, J
Critical reviews in microbiology. 2013;(3):247-55
Abstract
At present, the modern two-step fermentation process is one of the major approaches for the industrial production of vitamin C. The key step in this process is the conversion of L-sorbose to 2-keto-L-gulonic acid (2-KLG), the vitamin C precursor, which is accomplished by an artificial microbial ecosystem consisting of Ketogulonicigenium vulgare and Bacillus megaterium. This review describes current progress in understanding this ecosystem, not only the individual physiological characteristics of the two strains, but also the interactions between them. Special emphasis is placed on recent systems biology studies of the ecosystem. We also discuss the regulation and improvement of this ecosystem, including analysis of the fermentation medium components and genetic engineering and optimum fermentative strategies. Finally, perspectives on the knowledge and engineering of this important artificial microbial ecosystem are discussed.
4.
Reconstruction and analysis of a genome-scale metabolic model of the vitamin C producing industrial strain Ketogulonicigenium vulgare WSH-001.
Zou, W, Liu, L, Zhang, J, Yang, H, Zhou, M, Hua, Q, Chen, J
Journal of biotechnology. 2012;(1):42-8
Abstract
Ketogulonicigenium vulgare WSH001 is an industrial strain commonly used in the vitamin C producing industry. In order to acquire a comprehensive understanding of its physiological characteristics, a genome-scale metabolic model of K. vulgare WSH001, iWZ663, including 830 reactions, 649 metabolites, and 663 genes, was reconstructed by genome annotation and literature mining. This model was capable of predicting quantitatively the growth of K. vulgare under L-sorbose fermentation conditions and the results agreed well with experimental data. Furthermore, phenotypic features, such as the defect in sulfate metabolism hampering the syntheses of L-cysteine, L-methionine, coenzyme A (CoA), and glutathione, were investigated and provided an explanation for the poor growth of K. vulgare in monoculture. The model presented here provides a validated platform that can be used to understand and manipulate the phenotype of K. vulgare to further improve 2-KLG production efficiency.
5.
Metabolic engineering of microorganisms for vitamin C production.
Zhou, J, Du, G, Chen, J
Sub-cellular biochemistry. 2012;:241-59
Abstract
Vitamin C, an important organic acid, is widely used in the industries of pharmaceuticals, cosmetics, food, beverage and feed additives. Compared with the Reichstein method, biotechnological production of vitamin C is an attractive approach due to the low cost and high product quality. In this chapter, biosynthesis of vitamin C, including one-step fermentation processes and two-step fermentation processes are discussed and compared. Furthermore, the prospects of the biotechnological production of vitamin C are also presented.