Transcriptional control of hydrogen production during mixed carbon fermentation by hydrogenases 4 (hyf) and 3 (hyc) in Escherichia coli

► H2 producing hydrogenases (Hyd) were studied in E. coli grown on mixed carbon at pH 6.5. ► Using hyfG mutant, activity of Hyd-4 involved in H2 production was revealed. ► Using appropriate mutants, Hyd-1 and Hyd-2 were shown to operate in a reversed mode. ► H2 production was inhibited by N,N′-dicyclohexylcarbodiimide in fhlA and hyfG fhlA mutants. ► Interactions between Hyd enzymes and of FhlA protein with the F0F1-ATPase are suggested.