Dissimilatory Sulfate- and Sulfur-Reducing Prokaryotes

Three types of hydrogenases have been isolated from the sulfate-reducing bacteria of the genus Desulfovibrio. They differ in their subunit and metal compositions, physico-chemical characteristics, amino acid sequences, immunological reactivities, gene structures and their catalytic properties. Broadly, the hydrogenases can be considered as 'iron only' hydrogenases and nickel-containing hydrogenases. The iron-sulfur-containing hydrogenase ([Fe] hydrogenase) contains two ferredoxin-type (4Fe-4S) clusters and an atypical iron-sulfur center believed to be involved in the activation of H2. The [Fe] hydrogenase has the highest specific activity in the evolution and consumption of hydrogen and in the proton-deuterium exchange reaction and this enzyme is the most sensitive to CO and NO2-. It is not present in all species of Desulfovibrio. The nickel-(iron-sulfur)-containing hydrogenases [( NiFe] hydrogenases) possess two (4Fe-4S) centers and one (3Fe-xS) cluster in addition to nickel and have been found in all species of Desulfovibrio so far investigated. The redox active nickel is ligated by at least two cysteinyl thiolate residues and the [NiFe] hydrogenases are particularly resistant to inhibitors such as CO and NO2-. The genes encoding the large and small subunits of a periplasmic and a membrane-bound species of the [NiFe] hydrogenase have been cloned in Escherichia (E.) coli and sequenced. Their derived amino acid sequences exhibit a high degree of homology (70%); however, they show no obvious metal-binding sites or homology with the derived amino acid sequence of the [Fe] hydrogenase. The third class is represented by the nickel-(iron-sulfur)-selenium-containing hydrogenases [( NiFe-Se] hydrogenases) which contain nickel and selenium in equimolecular amounts plus (4Fe-4S) centers and are only found in some species of Desulfovibrio. The genes encoding the large and small subunits of the periplasmic hydrogenase from Desulfovibrio (D.) baculatus (DSM 1743) have been cloned in E. coli and sequenced. The derived amino acid sequence exhibits homology (40%) with the sequence of the [NiFe] hydrogenase and the carboxy-terminus of the gene for the large subunit contains a codon (TGA) for selenocysteine in a position homologous to a codon (TGC) for cysteine in the large subunit of the [NiFe] hydrogenase. EXAFS and EPR studies with the 77Se-enriched D. baculatus hydrogenase indicate that selenium is a ligand to nickel and suggest that the redox active nickel is ligated by at least two cysteinyl thiolate and one selenocysteine selenolate residues.(ABSTRACT TRUNCATED AT 400 WORDS)

The three classes of hydrogenases from sulfate-reducing bacteria of the genus Desulfovibrio

https://mmbr.asm.org/content/mmbr/30/4/732.full.pdf

Classification of Desulfovibrio species, the nonsporulating sulfate-reducing bacteria.

Classification of the spore-forming sulfate-reducing bacteria.

The Main Outlines of Bacterial Classification

Since first discovered by J~eijerincl~ in 1895 (5) in di tch and canal mud and soil, the bacter ia have been repea ted ly recovered from the~e hab i ta t s and also found in ocean mud and sea sand, bo t tom deposits of the Black Sea, and other saline basins, sand and c lay of dunes and polders, springs, sewage, brines of oil wells and water a t the bo t tom of gasoline storage tanks . The b lack color of muds and c lay caused b y the precipi ta t ion of iron sulfide a t tes t s to their act ivi ty. The oxidat ion of this iron sulfide plays an impor tan t pa r t in the reclamat ion of the soils of the Dutch polder land (16). Von Wol. zogen Ki~hr ascribes to these bacter ia the corrosion of iron conduits under anaerobic conditions in ground containing considerable amounts of sulfate (37, 38). I t is believed t ha t t hey were concerned with an explosion of a gasoline storage t ank (39, 9), the corrosion of concrete (2) and the periodic destruct ion of large numbers of fish in waters of the South African coas~ (11). I t is even possible t ha t some deposits of mineral sulfides have been formed through the ac t iv i ty of the sulfate-reducing bacter ia (4). The distr ibut ion, importance and general characterist ics of the bacter ia have been so adequate ly discussed b y Bears (1) and others (8, 40, 3) during recent years tha t a detai led review is tmnecessary.

Robert L. Starkey

Papers

A study of spore formation and other morphological characteristics of vibrio desulfuricans