Ethanol production from starch by a coimmobilized mixed culture system of Aspergillus awamori and Zymomonas mobilis
The production of ethanol from starch by a coimmobilized mixed culture system of aerobic and anaerobic microorganisms in Ca-alginate gel beads was investigated. The mold Aspergillus awamori was used as an aerobic amylolytic microorganism and an anaerobic bacterium, Zymomonas mobilis, as an ethanol producer. By controlling the mixing ratio of the microorganisms in the inoculum size, a desirable coimmobilized mixed culture system, in which the aerobic mycelia grew on and near the oxygen-rich surface of the gel beads while the anaerobic bacterial cells mainly grew in the oxygen-deficient central part of the gel beads, was naturally established under the aerobic culture conditions, and ethanol could be directly produced from starch by the system. The ethanol productivity by the system in flask culture was particularly affected by the shear stress (dependent on the shaking speed) which controlled the mycelial growth on the surface of the gel beads. Under optimum culture conditions in the flask culture, the glucose produced was instantly consumed, and was not observed in the culture broth; the final concentration of ethanol produced from 100 g/L starch was 25 g/L and the yield coefficient for ethanol, Y/sub p/s/, was 0.38. The ethanol productivity by the coimmobilized mixed culture system was compared with those by other various culture systems and the advantages of the system were clarified.
- Research Organization:
- Univ. of Tsukuba, Ibaraki, Japan
- OSTI ID:
- 6823249
- Journal Information:
- Biotechnol. Bioeng.; (United States), Journal Name: Biotechnol. Bioeng.; (United States) Vol. 28:12; ISSN BIBIA
- Country of Publication:
- United States
- Language:
- English
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AEROBIC CONDITIONS
ALCOHOLS
ANAEROBIC CONDITIONS
ASPERGILLUS
BACTERIA
BIOCONVERSION
BIOSYNTHESIS
CARBOHYDRATES
CELL CULTURES
CHEMICAL REACTIONS
DECOMPOSITION
ENZYMATIC HYDROLYSIS
ENZYME ACTIVITY
ETHANOL
FERMENTATION
FUNGI
HYDROLYSIS
HYDROXY COMPOUNDS
IMMOBILIZED CELLS
LYSIS
MICROORGANISMS
ORGANIC COMPOUNDS
PLANTS
POLYSACCHARIDES
PRODUCTIVITY
REAGENTS
SACCHARIDES
SOLVOLYSIS
STARCH
SYNTHESIS
ZYMOMONAS MOBILIS