The use of a thermotolerant fermentative Kluyveromyces marxianus IMB3 yeast strain for ethanol production

Abstract

An investigation was carried out on the growth and ethanol production of a novel thermotolerant ethanol-producing Kluyveromyces marxianus IMB3 yeast strain. It grew aerobically on glucose, lactose, cellobiose, xylose and whey permeate and fermented all the above carbon sources to ethanol at 45 OC. This strain was capable of growing under anaerobic chemostat fermentation conditions at 45 OC and a dilution rate of 0.15 h-l and produced I 0 . 9 g / l biomass and 1.8% (v/v) ethanol. An increase in biomass (up to 10.0 g/l) and ethanol (up to 4.3% v / v at 45 "C and 7.7% v / v at 40 "C) were achieved by applying a continuous two-stage fermentation in sequence (one aerobic and one anaerobic stage) or a two-stage anaerobic fermentation with cell recycling. Potential applications, involving alcohol production systems, for use in dairy and wood related industries, were. discussed.

Ethanol and xylitol production from glucose and xylose at high temperature by Kluyveromyces sp. IIPE453

“…Figure 2 shows the growth and ethanol production simultaneously with speciWc growth rate of 0.23 h ¡1 on glucose, whereas on xylose, the cells grew with speciWc growth rate of 0.34 h ¡1 without producing ethanol in aerobic conditions. Banat et al [5] reported speciWc growth rate of Kluyveromyces marxianus IMB3 0.63 and 0.19 h ¡1 on glucose and xylose, respectively, in batch fermentation at 50°C.…”

“…The strain has the ability to convert hexose sugars to cell mass as well as ethanol during the growth phase. This ability shows that the yeast follows the Crabtree rather than the Pasteur eVect [5]. The yeast Saccharomyces cerevisiae also follows Crabtree [23].…”

High alcohol production by solid substrate fermentation from starchy substrates using thermotolerant Saccharomyces cerevisiae

“…The production of ethanol by yeast fermentation in tropical countries especially during summer months is not economically viable because of high energy input required to cool the reactors inorder to maintain the temperature during the fermentation process [1]. Thermotolerant yeasts offer potential advantages in alcohol industry by reducing the cost of ethanol distillation saving of energy by avoiding the need to cool reactors and in having faster fermentation rates which makes the process economical [2,3]. Although ethanol is produced by the process of submerged fermentation in various parts of the world, there is tremendous scope for Solid Substrate Fermentation (SSF) because of the following potential advantages [4±6]: (a) less requirement of water (especially attractive in summer months when water is scarce), (b) smaller volumes of fermentation mash, (c) less physical energy requirement, (d) less capital investment, (e) less operating costs and lower space requirement, (f) reduced reactor volumes, easier product recovery less liquid waste to be disposed of and hence less pollution problems.…”

Automated UV-C Mutagenesis of Kluyveromyces marxianus NRRL Y-1109 and Selection for Microaerophilic Growth and Ethanol Production at Elevated Temperature on Biomass Sugars

“…[4][5][6][7][8][9][10][11][12][13] Recently, increasing attention has been directed toward developing microbial catalysts for ethanol production at elevated temperatures. [14][15][16][17][18] Fermentation processes conducted at elevated temperatures will significantly reduce cooling costs, improve efficiency of simultaneous saccharification and fermentation, allow continuous ethanol removal by evaporation under reduced pressure, and reduce risk of contamination, all of which would improve profitability of fuel ethanol production from biomass. 15,16,18,19 The temperatures suitable for conventional strains of S. cerevisiae are relatively low (25 to 30 °C), although some S. cerevisiae strains have been isolated that are able to produce ethanol efficiently at 40 °C or 42 °C.…”