The work describes a novel approach for sustained photobiological production of H(2) gas via the reversible hydrogenase pathway in the green alga Chlamydomonas reinhardtii. This single-organism, two-stage H(2) production method circumvents the severe O(2) sensitivity of the reversible hydrogenase by temporally separating photosynthetic O(2) evolution and carbon accumulation (stage 1) from the c...

Hydrogen production by microorganisms is often described as a promising sustainable and clean energy source, but still faces several obstacles, which prevent practical application. Among them, oxygen sensitivity of hydrogenases represents one of the major limitations hampering the biotechnological implementation of photobiological production processes. Here, we describe a hierarchical biodivers...

[NiFe]-hydrogenases generally carry the bimetallic Ni-Fe reaction center on their largest subunit. The [NiFeSe]-hydrogenase Vhu from Methanococcus voltae has an unusual subunit composition. Some of the amino acids participating in the formation of the reaction center are within a separate, very small subunit, called VhuU. It consists of only 25 amino acids and contains the selenocysteinyl resid...

The nucleotide sequence has been determined for a twelve-gene operon of Escherichia coli designated the hyf operon (hyfABCDEFGHIR-focB). The hyf operon is located at 55.8-56.0 min and encodes a putative nine-subunit hydrogenase complex (hydrogenase four or Hyf), a potential formate- and sigma 54-dependent transcriptional activator, HyfR (related to FhlA), and a possible formate transporter, Foc...

Hydrogen evolution is observed in the green alga Scenedesmus obliquus after a phase of anaerobic adaptation. In this study we report the biochemical and genetical characterization of a new type of iron hydrogenase (HydA) in this photosynthetic organism. The monomeric enzyme has a molecular mass of 44.5 kDa. The complete hydA cDNA of 2609 base pairs comprises an open reading frame encoding a pol...

Hydrogenase-mediated reduction of flavin mononucleotide by H 2 is exploited to enable cleaner application nitroreductase enzymes for aromatic nitro functional groups. This turns the overall reaction into a biocatalytic hydrogenation. Use flavin-containing nitroreductases in industrial biotechnology typically relies upon NADH or NADPH as reductant, together with glucose dehydrogenase and regener...

BACKGROUND Several recent studies have reported successful hydrogen (H2) production achieved via recombinant expression of uptake [NiFe]-hydrogenases from Hydrogenovibrio marinus, Rhodobacter sphaeroides, and Escherichia coli (hydrogenase-1) in E. coli BL21(DE3), a strain that lacks H2-evolving activity. However, there are some unclear points that do not support the conclusion that the recombin...

Two hydrogenases from the methanogenic bacterium Methanobacterium thermoautotrophicum strain DeltaH have been purified and contain tightly bound nickel as well as the anticipated iron/sulfur atoms with a fixed ratio of 15-20 iron atoms per nickel. One hydrogenase reduces the 8-hydroxy-5-deazaflavin coenzyme factor 420 (F(420)), whereas the other has been purified as a methyl viologen-reducing h...