1. Department of Chemical and Biomolecular Engineering; University of Illinois, Urbana-Champaign; 600 South Mathews Ave. Urbana IL 61801 USA
2. Energy Biosciences Institute; University of Illinois, Urbana-Champaign; 1206 W Gregory Dr. Urbana IL 61801 USA
3. Current address: Institute of Industrial Science; The University of Tokyo; Komaba 4-6-1, Meguro Tokyo 153-8505 Japan