Surface display of a functional minicellulosome by intracellular complementation using a synthetic yeast consortium and its application to cellulose hydrolysis and ethanol production.
In this paper, we report the surface assembly of a functional minicellulosome by using a synthetic yeast consortium. The basic design of the consortium consisted of four different engineered yeast strains capable of either displaying a trifunctional scaffoldin, Scaf-ctf (SC), carrying three divergent cohesin domains from Clostridium thermocellum (t), Clostridium cellulolyticum (c), and Ruminococcus flavefaciens (f), or secreting one of the three corresponding dockerin-tagged cellulases (endoglucanase [AT], exoglucanase [EC/CB], or β-glucosidase [BF]). The secreted cellulases were docked onto the displayed Scaf-ctf in a highly organized manner based on the specific interaction of the three cohesin-dockerin pairs employed, resulting in the assembly of a functional minicellulosome on the yeast surface. By exploiting the modular nature of each population to provide a unique building block for the minicellulosome structure, the overall cellulosome assembly, cellulose hydrolysis, and ethanol production were easily fine-tuned by adjusting the ratio of different populations in the consortium. The optimized consortium consisted of a SC:AT:CB:BF ratio of 7:2:4:2 and produced almost twice the level of ethanol (1.87 g/liter) as a consortium with an equal ratio of the different populations. The final ethanol yield of 0.475 g of ethanol/g of cellulose consumed also corresponded to 93% of the theoretical value. This result confirms the use of a synthetic biology approach for the synergistic saccharification and fermentation of cellulose to ethanol by using a yeast consortium displaying a functional minicellulosome.
Tsai
Shen-Long
SL
Department of Chemical and Environmental Engineering, University of California, Riverside, CA 92521, USA.
Goyal
Garima
G
Chen
Wilfred
W
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002482:Cellulose / Q000378:metabolism*; D044603:Cellulosomes / Q000235:genetics* / Q000378:metabolism*; D046973:Ruminiclostridium cellulolyticum / Q000235:genetics; D048013:Acetivibrio thermocellus / Q000235:genetics; D000431:Ethanol; D006868:Hydrolysis; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D045857:Ruminococcus / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000201:enzymology* / Q000235:genetics
D001426:Bacterial Proteins; D008565:Membrane Proteins; D011994:Recombinant Proteins; C105449:SdbA protein, bacteria; D000431:Ethanol; D002482:Cellulose