摘要:
Thermophilic gram-positive anaerobic host cells, for example Thermoanaerobacterium saccharolyticum (“T sacch”), express heterologous biomass degrading enzymes, such as cellulases, and are able to produce useful fermentation products from cellulose. Useful fermentation products include, for example, ethanol, acetic acid, lactic acid or CO2. In order to provide maximum expression and activity levels, biomass degrading enzymes can be expressed from codon-optimized nucleotide sequences, can be expressed under the control of a high-efficiency promoter, and/or can be fused to a signal peptide. In addition, the host cell, for example, a T sacch host cell, can be genetically altered to further improve ethanol production, for example by disrupting the production of organic products other than ethanol.
摘要:
The present invention provides for heterologous expression of termite and termite-associated symbiont cellulases. The cellulases can, for example, be codon-optimized and expressed in yeast host cells, such as the yeast Saccharomyces cerevisiae. The cellulases can also be co-expressed in host cells with other cellulases. The expression in such host cells of the termite and termite-associated symbiont cellulases, and variants and combinations thereof, result in yeast with improved cellulosic activity. Thus, such genes and expression systems are useful for efficient and cost-effective consolidated bioprocessing systems.
摘要:
The present invention is directed to the construction of prototrophic, cellulo lytic strains of Saccharomyces cerevisiae with tethered and secreted cellulases and selection-based improvement of growth on cellulose by these strains. In some embodiments, host cells of the invention are able to produce ethanol using crystalline cellulose as a sole carbon source.