期刊
MICROBIAL CELL FACTORIES
卷 13, 期 -, 页码 -出版社
BMC
DOI: 10.1186/s12934-014-0146-8
关键词
L-ascorbic acid; D-sorbitol dehydrogenase; Poly(A/T) tails; Immobilization; Fed-batch fermentation
资金
- National High Technology Research and Development Program of China (863 Program) [2012AA022103]
- National Natural Science Foundation of China [21406087]
- Program for New Century Excellent Talents in University [NCET-12-0876]
- Foundation for the Author of National Excellent Doctoral Dissertation of PR China (FANEDD) [201256]
- Priority Academic Program Development of Jiangsu Higher Education Institutions
- Fundamental Research Funds for the Central Universities [JUSRP211A25]
- 111 Project [111-2-06]
Background: Production of L-sorbose from D-sorbitol by Gluconobacter oxydans is the first step to produce L-ascorbic acid on industrial scale. The sldhAB gene, which encodes the sorbitol dehydrogenase (SLDH), was overexpressed in an industrial strain G. oxydans WSH-003 with a strong promoter, P-tufB. To enhance the mRNA abundance, a series of artificial poly(A/T) tails were added to the 3'-terminal of sldhAB gene. Besides, their role in sldhAB overexpression and their subsequent effects on L-sorbose production were investigated. Results: The mRNA abundance of the sldhAB gene could be enhanced in G. oxydans by suitable poly(A/T) tails. By self-overexpressing the sldhAB gene in G. oxydans WSH-003 with an optimal poly(A/T) tail under the constitutive promoter P-tufB, the titer and the productivity of L-sorbose were enhanced by 36.3% and 25.0%, respectively, in a 1-L fermenter. Immobilization of G. oxydans-sldhAB6 cells further improved the L-sorbose titer by 33.7% after 20 days of semi-continuous fed-batch fermentation. Conclusions: The artificial poly(A/T) tails could significantly enhance the mRNA abundance of the sldhAB. Immobilized G. oxydans-sldhAB6 cells could further enlarge the positive effect caused by enhanced mRNA abundance of the sldhAB.
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