Kinetics and thermodynamics of ethanol production by a thermotolerant mutant of Saccharomyces cerevisiae in a microprocessor-controlled bioreactor
Authors:
- 1 May 2005
- journal article
- research article
- Published by Oxford University Press (OUP) in Letters in Applied Microbiology
- Vol. 40 (5) , 316-321
Abstract
The present investigation deals with the development of thermotolerant mutant strain of yeast for studying enhanced productivity of ethanol from molasses in a fully controlled bioreactor. The parental culture of Saccharomyces cerevisiae ATCC 26602 was mutated using UV treatment. A single thermotolerant mutant was isolated after extensive screening and optimization, and grown on molasses medium in liquid cultures. The mutant was 1.45-fold improved than its wild parent with respect to ethanol productivity (7.2 g l-1 h-1), product yield (0.44 g ethanol g-1 substrate utilized) and specific ethanol yield (19.0 g ethanol g-1 cells). The improved ethanol productivity was directly correlated with titres of intracellular and extracellular invertase activities. The mutant supported higher volumetric and product yield of ethanol, significantly (P<or=0.05) higher than the parental and other strains. The mutated cultures produced 1.8- and 2.6-fold more extracellular and intracellular invertase productivity, respectively, than that produced by its wild parent at 40 degrees C. Thermodynamic studies revealed that the cell system exerted protection against thermal inactivation during formation of products. A mutant derivative of Sacchromyces cerevisiae with improved productivity of ethanol and invertases has been obtained, which showed concomitant improvement in thermostability of endogenous metabolism for formation of both ethanol and invertases. The results of the present study are of commercial value as the mutant can be used for ethanol production in parts of Pakistan where the temperature may go up to 40 degrees C in April. Ethanol product yield coefficient and volumetric productivity, revealed the hyper-productivity of ethanol from molasses at 40 degrees C, which is not appropriate for wild organism.Keywords
This publication has 16 references indexed in Scilit:
- Isolation and characterization of two specific regulatory Aspergillus niger mutants shows antagonistic regulation of arabinan and xylan metabolismMicrobiology, 2003
- Hyperthermostabilization of Bacillus licheniformis α-amylase and modulation of its stability over a 50°C temperature rangeProtein Engineering, Design and Selection, 2003
- Effect of temperature and cell density on ethanol fermentation by a thermotolerant aquatic yeast strain isolated from a hot spring environmentFisheries Science, 2002
- Improved Properties of Baker's Yeast Mutants Resistant to 2-Deoxy- d -GlucoseApplied and Environmental Microbiology, 2001
- Simultaneous Saccharification and Fermentation of Steam-Pretreated Spruce to EthanolApplied Biochemistry and Biotechnology, 2000
- Simultaneous effects of immobilization and substrate protection on the thermodynamics of glucose isomerase activity and inactivationEnzyme and Microbial Technology, 1997
- The heat shock and ethanol stress responses of yeast exhibit extensive similarity and functional overlapFEMS Microbiology Letters, 1995
- Characterization and potential industrial applications of five novel, thermotolerant, fermentative, yeast strainsWorld Journal of Microbiology and Biotechnology, 1995
- Ethanol production at 45 ° by an alginate-immobilized, thermotolerant strain of Kluyveromyces marxianus following growth on glucose-containing mediaBiotechnology Letters, 1994
- Mannose fermentation by an ethanologenic recombinant Escherichia coliBiotechnology Letters, 1993