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Genetic engineering to improve 1,3-propanediol production in an isolated Citrobacter freundii strain

Paper ID Volume ID Publish Year Pages File Format Full-Text
34472 45027 2015 13 PDF Available
Title
Genetic engineering to improve 1,3-propanediol production in an isolated Citrobacter freundii strain
Abstract

•Citrobacter freundii strain was genetically modified for improved 1,3-PD production.•Overexpression of PDOR activity in a custom made vector was carried out.•Accumulation of toxic 3-HPA was decreased in the modified strain.•The modified strain produced more 1,3-PD in flask and bioreactor cultures.

In this study, the isolated strain, Citrobacter freundii AD970, was genetically modified to improve production of 1,3-propanediol (1,3-PD). The strain was modified through overexpression of 1,3-PD oxidoreductase (PDOR from Shimwellia blattae), catalyzing the final step of glycerol-to-1,3-PD conversion. The aim of such approach was to decrease accumulation of toxic 3-hydroxypropionaldehyde (3-HPA) and to increase 1,3-PD synthesis. To this end, a genetic construct suitable for the modification of the strain was developed. Our results showed that PDOR was successfully overexpressed in the novel expression system. Flask cultivations in a glycerol-based medium demonstrated that the modified strain produced nearly two-fold higher concentrations of 1,3-PD (8.6 vs. 4.75 g/L). During bioreactor fed-batch cultivations in a glycerol-based medium, accumulation of 3-HPA was successfully decreased, leading to enhanced 1,3-PD synthesis (35.6 vs. 25.5 g/L), at higher yield (0.49 vs. 0.44 mol/mol at 48 h) and productivity (12.41 vs. 8.06 g1,3-PD/gDCW and 0.32 vs. 0.23 g1,3-PD/(L*h)). Considering the final volume of the fed-batch cultures, the V + I strain synthesized 20 g more of 1,3-PD (49.9 g vs. 29.9 g). To the best of our knowledge, this is the first report on genetic engineering of a wild-type Citrobacter strain to modulate the 1,3-PD synthesis pathway.

Keywords
1,3-Propanediol; Glycerol; Citrobacter freundii; Genetic engineering; 1,3-Propanediol oxidoreductase
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Genetic engineering to improve 1,3-propanediol production in an isolated Citrobacter freundii strain
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Publisher
Database: Elsevier - ScienceDirect
Journal: Process Biochemistry - Volume 50, Issue 1, January 2015, Pages 48–60
Authors
, , , , , ,
Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us