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KMID : 0613820190290030376
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Journal of Life Science
2019 Volume.29 No. 3 p.376 ~ p.381
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Construction of Yeast Strain Suitable for Bioethanol Production by Using Fusion Method
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Kim Yeon-Hee
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Abstract
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To construct useful yeast strain for bioethanol production, we improved yeast harboring various phenotypes by using yeast protoplast fusion method. In this study, S. cerevisiae BYK-F11 strain which have ethanol tolerance, thermotolerance and β-glucanase activity and P. stipitisΔura strain which has xylose metabolism pathway were fused by genome shuffling. P. stipitisΔura strain was constructed for protoplast fusion by URA3 gene disruption, resulting in uracil auxotroph. By protoplast fusion, several fused cells were selected and BYKPS-F8 strain (fused cell) showing both karyotypes from two parent strains (S. cerevisiae BYK-F11 and P. stipitisΔura strain) among 22 fused cells was finally selected. Sequentially, various phenotypes such as β-glucanase activity, xylose utility, ethanol tolerance, thermotolerance and ethanol productivity were analyzed. The BYKPS-F8 strain obtained β-glucanase activity from BYK-F11 strain and 1.2 fold increased xylose utility from P. stipitisΔura strain. Also, the BYKPS-F8 strain showed thermotolerance at 40℃ and increased ethanol tolerance in medium containing 8% ethanol. In this fused cell, 7.5 g/l ethanol from 20 g/l xylose was produced and the multiple phenotypes were stably remained during long term cultivation (260 hr). It was proved that novel biological system (yeast strains) is easily and efficiently bred by protoplast fusion among yeasts having different genus.
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KEYWORD
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Ethanol tolerance, karyotype, protoplast fusion, thermotolerance, xylose utility
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