Escherichia coli HD701, a hydrogenase-upregulated strain, has the potential for industrial-scale H, production but is unable to metabolise sucrose, which is a major constituent of many waste materials that could be used as feedstocks for H-2 production processes. A 70 kb plasmid (pUR400), which carries the genes necessary for sucrose transport into the cell and its metabolism, was conjugated into E. coli strains HD701 and FTD701 [a derivative of HD701 which has a deletion of the tatC gene of the twin arginine transport (Tat) protein system] from an E. coli K12 strain. Comparative studies on H, evolution by FTD701 and HD701, with and without the pUR400 plasmid, were made using sucrose as substrate. The parental strains did not evolve H2, although HD701/pUR400 and FTD701/pUR400 evolved 1.27 +/-0.09 and 1.38 +/- 0.05 ml H-2 mg dry wt(-1) 1 culture(-1), respectively over 10 h. This work provides the choice for using a recombinant E. coli strain, which produces H-2 from sucrose, as an alternative to coupling-in an upstream invertase, and hence this provides a simpler method for the bioproduction of H-2 from sucrose.