1. Energy Bioscience Institute; University of California; Berkeley CA 94720 USA
2. Department of Chemical and Biomolecular Engineering; University of California; Berkeley CA 94720 USA
3. BP North America; Berkeley CA 94720 USA
4. Current affiliation: BASF Corporation; 33 Wood Avenue South Iselin New Jersey 08830 USA
5. BP Formulated Products Technology; Technology Centre, Whitchurch Hill; Reading RG8 7QR UK