1. Department of Biological Systems Engineering Washington State University Richland WA 99354 USA
2. Current address: Center of Biomass Engineering/College of Agronomy and Biotechnology China Agricultural University Beijing 100193 PR China
3. Pacific Northwest National Laboratory 902 Battelle Boulevard Richland WA 99354 USA
4. National Bioenergy Center National Renewable Energy Laboratory 15013 Denver West Parkway Golden CO 80401 USA