Strategies for the production of cell wall-deconstructing enzymes in lignocellulosic biomass and their utilization for biofuel production

Microbial cell wall-deconstructing enzymes are widely used in the food, wine, pulp and paper, textile, and detergent industries and will be heavily utilized by cellulosic biorefineries in the production of fuels and chemicals. Due to their ability to use freely available solar energy, genetically engineered bioenergy crops provide an attractive alternative to microbial bioreactors for the production of cell wall-deconstructing enzymes. This review article summarizes the efforts made within the last decade on the production of cell wall-deconstructing enzymes in planta for use in the deconstruction of lignocellulosic biomass. A number of strategies have been employed to increase enzyme yields and limit negative impacts on plant growth and development including targeting heterologous enzymes into specific subcellular compartments using signal peptides, using tissue-specific or inducible promoters to limit the expression of enzymes to certain portions of the plant or certain times, and fusion of amplification sequences upstream of the coding region to enhance expression. We also summarize methods that have been used to access and maintain activity of plant-generated enzymes when used in conjunction with thermochemical pretreatments for the production of lignocellulosic biofuels

The quest for alternatives to microbial cellulase mix production: corn stover-produced heterologous multi-cellulases readily deconstruct lignocellulosic biomass into fermentable sugars

Abstract BACKGROUND: Production of cellulosic ethanol is still expensive compared with corn (maize) grain ethanol due to the high costs of bulk production of microbial cellulases. At least three cellulases including endo-cellulase, exo-cellulase and cellobiase are needed to convert cellulosic biomass into fermentable sugars. All these cellulases could be self-produced within cells of transgenic bio-energy crops. The production of heterologous Acidothermus cellulolyticus (E1) endo-cellulase in endoplasmic reticulum and mitochondria of green tissues of transgenic corn plants was recently reported, and it was confirmed that the heterologous E1 converts cellulose into fermentable sugars

Genetic Transformation of Common Bean (Phaseolus vulgaris L.) with the Gus Color Marker, the Bar Herbicide Resistance, and the Barley (Hordeum vulgare) HVA1 Drought Tolerance Genes

Five common bean (Phaseolus vulgaris L.) varieties including “Condor,” “Matterhorn,” “Sedona,” “Olathe,” and “Montcalm” were genetically transformed via the Biolistic bombardment of the apical shoot meristem primordium. Transgenes included gus color marker which visually confirmed transgenic events, the bar herbicide resistance selectable marker used for in vitro selection of transgenic cultures and which confirmed Liberty herbicide resistant plants, and the barley (Hordeum vulgare) late embryogenesis abundant protein (HVA1) which conferred drought tolerance with a corresponding increase in root length of transgenic plants. Research presented here might assist in production of better P. vulgaris germplasm