Fig. 2.

Identification and isolation of the thermostable HDCR. a The putative HDCR gene cluster of T. kivui compared to the HDCR gene cluster of A. woodii. Shown is the present identity of pairwise alignment of the deduced amino acid sequence. For hyc genes, only pairs showing highest percent identity are shown. b Hydrogen production from formate catalyzed by cell free extracts of T. kivui grown on different substrates. 50 mM formate was added to 0.5 mg cell free extract incubated at 60 °C in anoxic buffer (100 mM HEPES/NaOH, 2 mM DTE, pH 7.0) and production of H₂ was measured in the gas phase. c Denaturating SDS polyacrylamide gel electrophoresis of the fractions during isolation of the HDCR from T. kivui. 10 µg protein per lane; stained with Coomassie Brilliant blue. Right part, further separation of the small subunits by SDS polyacrylamide gel electrophoresis. LC–MS/MS was used to trace back the isolated protein to its encoding gene; A, fdhF1; B, hydA2; C, hycB2; D, hycB1