Engineered Yeast for Cellulosic Ethanol Production

Tech ID: 27365 / UC Case 2009-328-0

Background

Ethanol from renewable sources provides an attractive form of alternative energy. Cellulosic biomass such as plant material waste represents an inexpensive feedstock for sustainable ethanol production. However the main issue with cellulosic biomass use is the preparative steps necessary to degrade cellulose into ethanol. Specifically, the high cost of cellulases needed for cellulose degradation is one of the major obstacles in economically feasible ethanol production from biomass.

Brief Description

Prof. Wilfred Chen and his lab at the University of California, Riverside designed and expressed a cellulosome that simultaneously hydrolyzes cellulose and produces ethanol that has an efficiency that is four times greater when compared to free floating enzymes like cellulases. A cellulosome is a consortium of hydrolytic enzymes that is expressed on the surface of yeast. This novel cellulosome design was inspired by anaerobic microbes that use enzyme consortiums to achieve sufficient energy production in unfavorable conditions. In close proximity, the constituent enzymes in the consortium can work synergistically, rapidly converting cellulose into ethanol.

Fig

Fig. 1 shows the functional assembly of cellulosomes on the yeast cell surface. Cohesin and dockerin proteins are linked to the enzymes to help assemble the complex cellulosome.

Fig2

Fig. 2 shows time profiles of ethanol production from cellulose. A variety of different enzyme consortiums (At, At+Ec etc.) were used in the study, as well as free-floating cellulosomes and a control group (no cellulosome or free enzymes)

 

 

Advantages

  • Economically sustainable biofuels production for transportation and other uses
  • Modification of other bacterium for high-efficiency production

Patent Status

Country Type Number Dated Case
United States Of America Issued Patent 8,815,553 08/26/2014 2009-328
 

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Keywords

biofuels, cellulose, hydrolysis, ethanol, cellulosome, yeast, clean energy

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