Abstract
From an environmental standpoint, lignocellulosic biomass is a promising feedstock for conversion to fuels and other useful chemicals. However, commercialization of such biorefinery has not been achieved, largely due to high cost of microbial cellulases, used for enzymatic hydrolysis of cellulose to fermentable sugars. Transgenic plants expressing cellulases at high levels are expected as an alternative approach to cost-effective cellulase production. In this work, we introduced the hyperthermophilic cellulase gene from Pyrococcus horikoshii into the tobacco plastid genome. The transplastomic tobacco leaves accumulated the intact hyperthermophilic cellulase up to comparable level to Rubisco large subunit. Enzyme assays indicated that the active enzyme was retained not only in fresh leaves but also in dry ones. When grown on synthetic medium, there was no apparent difference in phenotype between the transformants and wild-type plants.
