Variant FhlA133 (Q11H, L14V, Y177F, K245R, M288K, and I342F) had eight- fold higher hydrogen production than FhlA wild-type under 30 min of anaerobic incubation in modified-complex 20 mM formate at 37ºC. The mechanism by which the FhlA133 mutations increase hydrogen production is by increasing the transcription of all of the genes activated by the native FhlA (FHL complex). Overall design: Strains: E. coli BW25113 fhlA/pCA24N-FhlA wild-type and E. coli BW25113 fhlA/pCA24N-FhlA133 (Q11H, L14V, Y177F, K245R, M288K, and I342F). Medium: Modified-complex 20 mM formate 1 mL of overnight culture in modified - complex 20 mM formate + Cm 30 µg/mL was inoculated in 9 mL of fresh modified - complex 20 mM formate + Cm 30 µg/mL and incubated anaerobically at 37oC in 27 mL glass vials. Time: 30 minutes Cell type: Suspension