Direct ethanol fermentation of the algal storage polysaccharide laminarin with an optimized combination of engineered yeasts.
Laminarin is the algal storage glucan and represents up to 35% of the dry weight of brown macroalgae. In this study, a novel laminarinase, Gly5M, was first found using focused proteome analysis of a laminarin-assimilating marine bacterium, Saccharophagus degradans, and the encoding gene was isolated. A Gly5M-displaying yeast strain was prepared with the cell surface display system using Saccharomyces cerevisiae. It showed a laminarin-degrading activity on the cell surface and caused the dominant accumulation of gentiobiose. The obtained gentiobiose was converted into glucose and could be assimilated by an Aspergillus aculeatus β-glucosidase (BG)-displaying yeast strain. When Gly5M- and BG-displaying yeasts were anaerobically cultivated together in fermentation medium containing 20g/L laminarin as a sole carbon source, the coculture system with the combination of optimized ratios of the 2 yeast strains directly produced 5.2g/L ethanol. This coculture system of the 2 engineered yeast strains would be a platform for the use of laminarin and contribute to the complete utilization of brown macroalgae.
Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
Keisuke
K
Motone
Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan; Japan Society for the Promotion of Science, Sakyo-ku, Kyoto 606-8502, Japan.
Toshiyuki
T
Takagi
Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan; Graduate School of Advanced Integrated Studies in Human Survivability, Kyoto University, Sakyo-ku, Kyoto 606-8306, Japan.
Yusuke
Y
Sasaki
Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
Kouichi
K
Kuroda
Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan. Electronic address: miueda@kais.kyoto-u.ac.jp.
Mitsuyoshi
M
Ueda
D034241:Alteromonadaceae; D049109:Cell Proliferation; D044602:Cellulases / Q000235:genetics / Q000378:metabolism; D018920:Coculture Techniques; D000431:Ethanol / Q000032:analysis / Q000378:metabolism*; D005285:Fermentation; D005936:Glucans / Q000032:analysis / Q000378:metabolism*; D060847:Metabolic Engineering / Q000379:methods*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism*; D012624:Seaweed
D005936:Glucans; D011994:Recombinant Proteins; D000431:Ethanol; C008247:laminaran; D044602:Cellulases
Cell surface engineering; Coculture; Ethanol; Laminarin; Macroalgae; Saccharomyces cerevisiae