tailieunhanh - Selection and identification of thermotolerant ethanol producing yeast strains

The objectives of this study are to select yeast strains capable of growth and ethanol production at elevated temperature from starters and to identification them to species. These results demonstrated that the K. marxianus ITB3 can be used for industrial ethanol production at high temperature in order to reduce energy consumption, especially in simultaneous saccharification and fermentation processes for production of ethanol from starchy and cellulosic materials that decreases the amount of saccharification enzymes and investment costs for a plant. | TẠP CHÍ SINH HỌC, 2012, 34(3SE): 125-131 SELECTION AND IDENTIFICATION OF THERMOTOLERANT ETHANOL PRODUCING YEAST STRAINS Tran Thanh Phong1*, Le Tan Hung1, Le Thi Bich Phuong1, Vo Thi Hanh1, Hasashi Hoshida2, Rinji Akada2 (1) Institute of Tropical Biology, VAST, (*)tranthanhphongitb@ (2) Yamaguchi University, Japan ABSTRACT: Among eight yeast strains isolated from starters in Vietnam, only one strain coded as ITB3 could grow well at 45°C with optical density (OD660nm) of that was equal to Kluyveromyces marxianus DMKU3-1042 strain (OD660nm of 4). At 30o C, the strain ITB3 fermented 10% (w/v) glucose to (v/v) ethanol in 14 hours at a yield of g ethanol/g glucose, or of theoretical yield that was slightly lower than that of K. marxianus DMKU3-1042 (produced % ethanol (v/v), g ethanol/g glucose, or 77% of theoretical yield). However, at 45oC, the strain ITB3 fermented 10% (w/v) glucose to (v/v) ethanol at a yield of g ethanol/g glucose, or of theoretical yield that was slightly higher than that of K. marxianus DMKU3-1042, (produced % (v/v), g ethanol/g glucose, or of theoretical yield). The strain ITB3 was identified as K. marxianus ITB3 based on the results of ITS rDNA sequencing and yeast mating. These results demonstrated that the K. marxianus ITB3 can be used for industrial ethanol production at high temperature in order to reduce energy consumption, especially in simultaneous saccharification and fermentation processes for production of ethanol from starchy and cellulosic materials that decreases the amount of saccharification enzymes and investment costs for a plant. Keywords: Kluyveromyces marxianus, ethanol fermentation, thermotolerant yeasts. INTRODUCTION In tropical countries, the ingenious alcoholic production has been done at high temperature because the day-time temperatures are high throughout the year ranging from 30 to 37oC. The advantages of traditional ethanol making at high .