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Evaluation of medium composition and fermentation parameters on pullulan production by Aureobasidium pullulans
Kuan-Chen Cheng1, Ali Demirci, Jeffrey M Catchmark
1Department of Agricultural and Biological Engineering, The Pennsylvania State University, University Park, PA 16802, USA.
Summary
This study optimized pullulan production by Aureobasidium pullulans using specific fermentation conditions. Key findings include enhanced pullulan yield and production rate through controlled pH, aeration, and agitation.
Area of Science:
- Microbiology
- Biotechnology
- Industrial Fermentation
Background:
- Pullulan, an exopolysaccharide, has diverse industrial applications.
- Optimizing pullulan production is crucial for economic viability.
- Aureobasidium pullulans is a key microorganism for pullulan biosynthesis.
Purpose of the Study:
- To enhance pullulan production by Aureobasidium pullulans.
- To investigate the effects of various fermentation parameters on pullulan yield.
- To determine optimal conditions for maximizing pullulan concentration and production rate.
Main Methods:
- Screening of carbon sources, yeast extract (YE) concentrations, and fermentation temperatures.
- Evaluation of different pH profiles, agitation speeds, and aeration rates.
- Assessment of fed-batch fermentation strategies and kinetic parameter optimization.
Main Results:
- Optimal initial conditions identified: 75 g/L sucrose, 3 g/L YE, 30°C, initial pH 5, yielding 20.7 g/L pullulan.
- Enhanced production to 25.8 g/L with a 0.68 g/L/h rate using optimized pH profile (pH 2.0 to 5.0), 200 rpm agitation, and 1.5 vvm aeration.
- Fed-batch fermentation showed no significant improvement; optimal conditions yielded 94.5% pullulan with 2.3 cP viscosity.
Conclusions:
- Fermentation parameter optimization significantly enhances pullulan production.
- Specific kinetic controls, including a dynamic pH shift, are critical for maximizing yield.
- The study provides a robust framework for industrial-scale pullulan biosynthesis.
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