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.
Author: Sha XuXiaobei WangGuocheng DuJingwen ZhouJian Chen
Credits/Source: Microbial Cell Factories 2014, 13:146
Published on: 2014-10-18
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