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A preliminary information about continuous fermentation using cell recycling for improving microbial xylitol
S S Silva1, A Q Chanto, M Vitolo
1Department of Biotechnology, Faculty of Chemical Engineering of Lorena, FAENQUIL/DEBIQ, Rod. Itajubá/Lorena km 74.5 Caixa Postal 116-12600-000, Lorena-São Paulo, Brazil. silvio@debiq.faenquil.br
Applied Biochemistry and Biotechnology
|August 12, 2004
Summary
Continuous fermentation with cell recycling using Candida guilliermondii FTI 20037 enhances xylitol production. This biotechnological approach offers advantages over chemical methods for producing this valuable sugar-alcohol.
Area of Science:
- Biotechnology
- Microbiology
- Biochemical Engineering
Background:
- Xylitol, a sugar-alcohol, possesses valuable properties like anticariogenicity and low caloric value, driving demand in food and pharmaceutical industries.
- Biotechnological xylitol production offers economic advantages over conventional chemical reduction of xylose.
- Optimizing fermentation efficiency and productivity relies on selecting appropriate microorganisms and process conditions.
Purpose of the Study:
- To evaluate a continuous culture system with cell recycling for enhanced xylitol production.
- To assess the capability of Candida guilliermondii FTI 20037 in a continuous fermentation setup.
- To investigate the impact of dilution rate on xylitol concentration and volumetric productivity.
Main Methods:
- A simple continuous culture system with cell recycling was employed in a 2-L bench-scale fermentor.
- Fermentation was initiated batchwise, followed by continuous feeding at a dilution rate (D) of 0.060/h after xylose depletion.
- Cell concentration was maintained at approximately 4.0 g/L during continuous operation.
Main Results:
- Continuous fermentation at D = 0.060/h achieved a xylitol concentration of approximately 15 g/L, representing a 35% increase.
- Volumetric productivity (Qp) was significantly influenced by the dilution rate, decreasing by 37% when D was reduced from 0.060/h to 0.025/h.
- The study demonstrated that continuous fermentation with cell recycling is a viable method for studying xylitol production.
Conclusions:
- Continuous fermentation with cell recycling is an effective strategy for improving xylitol production by Candida guilliermondii.
- Process conditions, particularly dilution rate, critically affect xylitol concentration and volumetric productivity.
- This approach provides a valuable platform for further research into optimizing yeast-based xylitol biosynthesis.