Improved ethanol production from sucrose by a mutant of Zymomonas mobilis lacking sucrases in immobilized cell fermentation
Ethanol production from sucrose by Zymomonas mobilis LS1A, a mutant strain lacking levansucrase (SacB) and intracellular sucrase (SacA), was studied in an alginate-immobilized cell fermentation. Since this mutant strain does not produce levan from sucrose, the immobilized cells were stable in sucros...
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Published in | Enzyme and microbial technology Vol. 22; no. 3; pp. 179 - 184 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
Amsterdam
Elsevier Inc
15.02.1998
Elsevier Science |
Subjects | |
Online Access | Get full text |
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Summary: | Ethanol production from sucrose by Zymomonas mobilis LS1A, a mutant strain lacking levansucrase (SacB) and intracellular sucrase (SacA), was studied in an alginate-immobilized cell fermentation. Since this mutant strain does not produce levan from sucrose, the immobilized cells were stable in sucrose fermentations and therefore produced higher amounts of ethanol (73.5 g l
−1) than that of its parent strain, B-806 (65.2 g l
−1) in an 18-h fermentation with 150 g sucrose l
−1. The absence of levansucrase and the decreased sucrose hydrolysis rate of this strain improved ethanol production without the formation of the by-products levan and sorbitol; however, an increase in the initial concentration of sucrose (150 to 250 g l
−1) in the fermentation medium favored the formation of sorbitol as a by-product. Coimmobilization of invertase with cells decreased the fermentation time from 18 to 12 h, thereby resulting in increased ethanol productivity from 4.08 g l
−1 h
−1 to 6.22 g l
−1 h
−1 and also increased the level of sorbitol. Decreased fermentation time (from 18 to 12 h) and increased ethanol productivity (6.3 g l
−1 h
−1) without any by-products were also achieved with the use of repeated batch fermentations of sucrose by immobilized cells of this mutant strain. |
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Bibliography: | ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 |
ISSN: | 0141-0229 1879-0909 |
DOI: | 10.1016/S0141-0229(97)00158-0 |