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KMID : 0545119940040030222
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Journal of Microbiology and Biotechnology
1994 Volume.4 No. 3 p.222 ~ p.229
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The Fermentation Characteristics of Newly Selected Thermotolerant Yeasts at High Temperature
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Sohn, Ho Yong
Park, Wan/Jin, Ingn Yol/Seu, Jung Hwn
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Abstract
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In order to develop a method of economical production and to reduce energy-consumption in fuel alcohol production, we investigated the fermentation characters of two newly selected thermotolerant yeasts. The RA-74-2 showed stable and superior fermentability between 30 and 40℃ in 20% glucose media in comparison to the industrial strains. The optimum concentration of glucose for economical fermentation at 40℃ was 15∼18%, and organic nitrogen was necessary for a satisfactory fermentation. The optimum pH was 4.0 and aeration was adversed for high temperature fermentation. Agitation was an important factor at 40℃ and the addition of magnesium ion 0.2% was required in this experiment. When the inoculum was increased, ethanol productivity as well as the speed of fermentation increased. On the other hand RA-912, which can grow at 48℃, showed similar fermentability between 30∼45℃ in 20% glucose media As the concentration of substrate decreased, fermentation ratio increased at 45℃ (45%, 65%, 95% fermentation ratio in 20%, 15%, 10% glucose media, respectively). Also, requirement of organic nitrogen and magnesium ion in RA-912 was similar in RA-74-2. The optimum pH for fermentation was 5.0, and the effects of agitation were enhanced at 37℃ than at 45℃. As the inoculum was increased, fermentation speed became more enhanced but the ethanol productivity was less affected. RA-912 showed fermentability with various substrates. Among the substrates used, inulin was the most promising substrate for the high-temperature fermentation. When 14.5% inulin was used as the substrate, 93% and 55% fermentation ratios were shown at 37℃ and 45℃, respectively.
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