529 / 2018-09-19 16:33:20

A functional complex designer cellulosome via self-surface assembly on Saccharomyces cerevisiae

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Cellulosomes are considered one of the most efficient systems for the degradation of plant cell wall polysaccharides. In complex cellulosome, enzymes assembly is mediated through binding of enzyme-burn dockerin modules to cohesin modules of the secondary scaffoldin which could bind to primary scaffoldin on the cell surface. Thus far, however, assemble such complex designer cellulosome on Saccharomyces cerevisiae cell is still challenging. Here we report an effort to self assembly complex designer cellulosome and direct covert cellulose to ethanol with CBP S.cerevisiae consortium. In this work, we employed “chimercal primary scaffoldin (scaf I)” strategy to assemble two secondary scaffoldins (scaf II) for binding cohesin cipa and scab respectively. As a result, we constructed four complexed designer cellulosomes: (A) cellulases bind to scaf I; (B) cellulases bind to scaf II-cipa; (C) cellulases bind to scaf II-scab; (D) cellulases bind to both scaf II-cipa and scaf II-scab. The performance of complex designer cellulosome with scaf II was more efficient in the hydrolysis of phosphoric acid swollen cellulose (PASC). During 72 h, cellulosome B and C produced 0.997 g/L and 0.815 g/L ethanol respectively, which was higher than 0.49 g/L of cellulosome A. However, 0.868 g/L ethanol of cellulosome D was lower than that of cellulosome B and C. These data indicated that the secondary scaffoldin could improve the synergy of cellulases, meanwhile, it is the steric hindrance effect between the two scaf IIs on the scaf I.