CHAPTER 5: Advances in the Genetic Manipulation of Cellulosic Bioenergy Crops for Bioethanol Production

The high cost, and huge amount needed, of hydrolysis enzymes are still considered key hindrances in commercial-scale bioethanol production from lignocellulosic biomass. Currently, although enzyme production using microbes has been greatly improved, large capital investments will be required to build and operate the numerous fermenters needed to meet the goal of 36 billion gallons of bioethanol production in the US per year by 2022. A potential alternative is to use plants as biofactories for production of these hydrolysis enzymes. Extensive research has been performed, and promising results have been achieved in this area. We will discuss recent accomplishments, problems, challenges, and solutions for achieving commercial-scale enzyme production from plants, especially bioenergy crops. In addition, possible alternative pretreatments with ligninase and hemicellulase enzymes are also discussed.