Fig. 5.

The engineered FTD147h3 strain displays hydrogenase activity. FTD147h3 (‘Fh3’) alone, or the strain transformed with pSUtat-Sh-GX-EF encoding accessory genes (‘Acc’), was cultured anaerobically in 0.4% (w/v) glucose, 2 mM cysteine, 2 mM ferric ammonium citrate. Cells were lysed by sonication resulting in a crude cell lysate, which was assayed for hydrogenase activity. ‘H₂ evolution’ activity refers to methyl viologen-dependent H₂ production measured in a modified Clark-type electrode. ‘H₂ oxidation’ activity refers to H₂-dependent benzyl viologen reduction monitored at 578 nm. N₂-saturated buffer (‘N2’) and unbroken intact cells (‘whole cells’) were used as controls. Error bars represent the standard error of three independent experiments.