Improved ethanol production from sucrose by a mutant of Zymomonas mobilis lacking sucrases in immobilized cell fermentation

T. R. Kannan, G. Sangiliyandi, P. Gunasekaran

Research output: Contribution to journalArticlepeer-review

29 Scopus citations

Abstract

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.

Original languageEnglish (US)
Pages (from-to)179-184
Number of pages6
JournalEnzyme and Microbial Technology
Volume22
Issue number3
DOIs
StatePublished - Feb 15 1998

Keywords

  • Ethanol
  • Fermentation
  • Immobilization
  • Levan
  • Sorbitol
  • Zymomonas mobilis

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Biochemistry
  • Applied Microbiology and Biotechnology

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