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KMID : 0545119940040040316
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Journal of Microbiology and Biotechnology
1994 Volume.4 No. 4 p.316 ~ p.321
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Application of Thermotolerant Yeast at High Temperature in Jar-fermentor Scale
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Sohn, Ho Yong
Kim, Young Ho/Rhee, In Koo/Seu, Jung Hwn
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Abstract
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We investigated the possibility of industrial application and economic process of high temperature fermentation by thermotolerant alcohol producing yeasts as previously reported. From the 20% glucose media, the RA-74-2 produced 11.8% (v/v) ethanol at 32℃ (0.5% inoculum) and 10.6% (v/v) ethanol at 40℃ (3% inoculum), respectively. Also, 11.3% (v/v) ethanol was produced for 96 hours in the temperature-gradient fermentation. These results suggest that the RA-74-2 could successfully be applied to save the cooling water and energy in industrial scale without re-investment or modification of established fermentation systems. When potato starch was used as the substrate for the RA-74-2, high temperature fermentation above 40℃ was more appropriate for industrial utilization because organic nitrogen was not necessary to economical fermentation. As the naked barley media just prior to industrial inoculation, taken from the Poongkuk alcohol industry Co., were used, 9.6% (v/v) ethanol was produced at 40℃ for 48 hours in jar-fermentor scale (actually, 9.5-9.8% (v/v) ethanol was produced at 30∼32℃ for 100 hours in industrial scale). The ethanol productivity was increased by the high glucoamylase activity as well as the high metabolic ratio at 40℃. Therefore, if the thermotolerant yeast RA-74-2 would be used in industrial scale, we could obtain a high productivity and saving of the cooling water and energy. Meanwhile, the RA-912 produced 6%(v/v) ethanol in 10% glucose media at 45℃ and showed the less ethanol-tolerance compared with industrial strains. As the produced alcohol was recovered by the vacuum evaporator at 45℃ in 15% glucose media, the final fermentation ratio was enhanced (76% of theoretical yields). This suggest that a hyperproductive process could be achieved by a continuous input of the substrate and continuous recovery of the product under vacuum in high cell-density culture.
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