Related Experiment Video
Updated: Jun 13, 2026
09:27
Immobilization of Multi-biocatalysts in Alginate Beads for Cofactor Regeneration and Improved Reusability
Published on: April 22, 2016
Sorbitol production using recombinant Zymomonas mobilis strain
Changjun Liu1, Hongwei Dong, Jianjiang Zhong
1State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China.
Journal of Biotechnology
|May 5, 2010
Summary
Engineered Zymomonas mobilis over-expresses glucose-fructose oxidoreductase (GFOR) for enhanced sorbitol and gluconic acid production. Divalent metal ions, particularly Zn(2+), significantly improved yields and reduced ethanol byproduct.
Area of Science:
- Biotechnology
- Metabolic Engineering
- Enzyme Technology
Background:
- Zymomonas mobilis is a bacterium used in industrial bioconversions.
- Glucose-fructose oxidoreductase (GFOR) catalyzes the conversion of glucose and fructose into sorbitol and gluconic acid.
- Optimizing GFOR activity and bioconversion pathways is crucial for efficient product generation.
Purpose of the Study:
- To construct a recombinant Zymomonas mobilis strain with over-expressed GFOR.
- To improve the bioconversion process for sorbitol and gluconic acid production.
- To investigate the effect of divalent metal ions on GFOR activity and product yields.
Main Methods:
- Construction of a recombinant Zymomonas mobilis strain using plasmid pHW20a-gfo for GFOR over-expression.
- Measurement of GFOR specific activity in the recombinant and wild strains.
- Evaluation of various divalent metal ions (e.g., Zn(2+), Ca(2+)) to optimize the bioconversion of glucose and fructose.
Main Results:
- The recombinant strain exhibited at least a two-fold increase in GFOR specific activity compared to the wild strain.
- Maximum volumetric and cellular GFOR activities reached 2.59 U/ml and 0.70 U/mg, respectively.
- Zn(2+) ions significantly reduced ethanol byproduct formation (from 16.7 to 1.8 g/l) and increased sorbitol yield to nearly 100%. Ca(2+) also enhanced sorbitol yield and facilitated gluconate separation.
Conclusions:
- Over-expression of GFOR in Zymomonas mobilis enhances enzyme activity for bioconversion.
- Divalent metal ions, especially Zn(2+), are effective in improving sorbitol and gluconic acid production efficiency by inhibiting competing pathways.
- This engineered strain and optimized process offer a promising approach for industrial production of valuable chemicals.
Related Concept Videos
01:27Production of Alcohol
Continuous fermentation is a key strategy in industrial ethanol production, particularly when efficiency, scalability, and high yields are essential. This approach allows for uninterrupted operation and optimized resource utilization. The primary feedstock, corn starch, undergoes enzymatic hydrolysis facilitated by α-amylase and glucoamylase. These enzymes break down the starch into fermentable sugars such as glucose, which are readily assimilated by fermentative microorganisms.Fermentation...
01:22Bioreactor Controls-III
Strain improvement is a foundational strategy in industrial microbiology aimed at maximizing microbial productivity, particularly because natural isolates typically yield commercially valuable products in very low concentrations. Although optimizing the culture medium and environmental conditions can improve yields, these adjustments are inherently limited by the organism’s genetic potential. As a result, the focus shifts toward genetic modifications to enhance biosynthetic capacity. The...
01:25Production of Organic Acids
Lactic acid, an important organic acid extensively applied in food, pharmaceutical, and biodegradable polymer industries, is primarily produced via microbial fermentation. This method is favored over chemical synthesis due to its environmental sustainability and capacity for enantiomerically pure product formation. Among various microbial processes, the fermentation of starch-based substrates stands out due to the abundance and renewability of raw materials like corn and potatoes.Hydrolysis of...
01:20Fates of Pyruvate
Pyruvate is the end product of glycolysis, where glucose is oxidized to pyruvate, simultaneously reducing NAD+ to NADH. Two molecules of ATP are also produced by substrate-level phosphorylation.
In aerobic organisms, pyruvate is metabolized via the citric acid cycle to produce reduced coenzymes NADH and FADH2. These coenzymes are then oxidized in the electron transport chain to produce ATP and, in the process, regenerate the NAD+ and FAD. As seen in some cell types and organisms, fermentation...
In aerobic organisms, pyruvate is metabolized via the citric acid cycle to produce reduced coenzymes NADH and FADH2. These coenzymes are then oxidized in the electron transport chain to produce ATP and, in the process, regenerate the NAD+ and FAD. As seen in some cell types and organisms, fermentation...
01:26Biosynthesis of Polysaccharides
Polysaccharides such as glycogen and starch are synthesized from nucleoside diphosphate sugars, primarily uridine diphosphate glucose (UDPG) and adenosine diphosphate glucose (ADPG). These activated glucose donors act as key intermediates in carbohydrate metabolism and biosynthesis. UDPG primarily involves glycogen synthesis in animals and many bacteria, while ADPG plays a fundamental role in starch synthesis in plants and certain bacteria.UDPG is formed when glucose-1-phosphate reacts with...
01:30Production of Pharmaceuticals
Industrial insulin production uses genetically engineered E. coli expressing a proinsulin gene controlled by a tryptophan promoter and containing a methionine linker for later cleavage. The cells also carry ampicillin resistance for selective growth. Seed cultures are stored at −80 °C and production begins by thawing a small amount to inoculate starter cultures, which are progressively scaled to a 50,000-L bioreactor. In the bioreactor, E. coli grow in nutrient-rich media under sterile, tightly...