Desulphovibrio

Corrosion of iron and steel, especially in anaerobic conditions such as waterlogged soils, is usually caused by sulphate-reducing bacteria of which the genus Desulphovibrio is the most commonly occuring. The presence of organic materials such as acetate often stimulates these organisms reducing... 

It can be seen from equation 2.14 that the ratio of iron corroded to iron in the form of sulphide should be 4 1, but values from 0.9 to 48 are commonly obtained experimentally. Subsequently it was shown by Booth and his co-workers that the ratios of the corrosion products were dependent on the particular strain of Desulphovibrio and on their rates of growth. Later the activity of the enzyme hydrogenase which bring about the reaction ... 

This is a simplified treatment but it serves to illustrate the electrochemical nature of rusting and the essential parts played by moisture and oxygen. The kinetics of the process are influenced by a number of factors, which will be discussed later. Although the presence of oxygen is usually essential, severe corrosion may occur under anaerobic conditions in the presence of sulphate-reducing bacteria Desulphovibrio desulphuricans) which are present in soils and water. The anodic reaction is the same, i.e. the formation of ferrous ions. The cathodic reaction is complex but it results in the reduction of inorganic sulphates to sulphides and the eventual formation of rust and ferrous sulphide (FeS). 

For example, a collation of results of five researchers in the 1970s and 1980s (Table 1) shows Bacillus, Pseudomonas, Proteus, Enterobacter and Escherichia to be the most commonly contaminating aerobic bacteria. In addition Opperman and Goll (1984) also investigated the incidence of anaerobic micro-organisms finding Bacteroides, Clostridium, Desulphovibrio and Bifidobacterium species. 

Some bacteria can give products a rancid smell others can impart the "sweet" odour of dirty drains by the production of certain pyrazine derivatives. Other bacteria, known as sulphate reducers, for example Desulphovibrio desulphuricans, are able, under anaerobic conditions, to utilise oxygen from sulphates leading ultimately to the formation of hydrogen sulphide. Opperman and Goll (1984) in their study of contaminated emulsion paints concluded that more than a quarter were infected with these and other anaerobic organisms. 

Figure 3.12 Active site of a reduced form of the Fe-only hydrogenase from Desulphovibrio desul-phuricans. The Fe atom on the right is defined as the proximal Fe (relative to the neighbouring [Fe-S] cluster), Fep the Fe atom on the left is defined as the distal Fe, FeD. The arrow indicates the potential hydron-binding site on FeD that is occupied by either HzO or an extrinsic CO in the structure of Cp I. Also shown is a close contact between the bridgehead atom X of the exogenous dithiolate ligand and the S atom of cysteine-178. (Reprinted with permission from Parkin et al., 2006. Copyright (2005) American Chemical Society.)...

Parkin, A., Cavazza, C., Fontecilla-Camps, J.C. and Armstrong, F.C. (2006) Electrochemical investigations of the interconversions between catalytic and inhibited states of the [FeFe]-hydrogenase from Desulphovibrio desulfuricans, JACS, 128, 16808-16815. 

Clostridium pasteurianum Desulfduruibrio gigas Desulphovibrio vulgaris 2Fe 2S Ferredoxin Cys-6 Cys-9 Cys-39 Cys-42 Watenpaugh et al. (1980) Frey et al. (1987) Adman et al. (1977)... 

Finally, as an alternative to colloidal metal particles it is possible to use hydrogenase,133,153 186 187-200,202,238"248 normally from Desulphovibrio vulgaris, or a synthetic analogue derived from Fe4S4 clusters248 in the presence of bovine serum albumin, as the redox catalyst for production of hydrogen from MVf and protons. 

Postgate, J.R., 1951. The reduction of sulphur compounds by Desulphovibrio desul-phuricans. J. Gen. Microbiol., 5 725—738. 

Jobson, A.M., 1975. Physiological Characterisation of a Desulphovibrio sp. Isolated from Crude Oil. Ph.D. Thesis, University of Alberta, 194 pp. 

Nickel has been found essential for nutrition in pigs, also rats (Nielsen, 1975). The essential quantity is so much smaller than was required for the earlier-established essential metals, that searchers had to wait for the discovery of new analytical techniques, such as neutron activation. The enzyme urease (in beans) is nickel-dependent (Dixon et al, 1975). Several bacteria have reductases that need nickel, such as Methanobacterium and Desulphovibrio (Thauer, 1980), and so do bacterial carbon monoxide dehydrogenases (Deake, Hu and Ward, 1980). 

Battersby AR, Jones K, McDonald E, Robinson JA, Morris HR (1977) The structures and chemistry of isobacteriochlorins from Desulphovibrio gigas. Tetrahedron Lett 25 2213... 

The first of these micro-organisms was isolated by Winogradsky in 1895, it is Clostridium pasteuricmum, sometimes called Amylobacter. In this anaerobe, unlike Rjhvsobium, fixation is not inhibited in the presence of carbon dioxide. The ability to fix nitrogen is widespread in the Clostridia and it has also been foimd in another anaerobe, Desulphovibrio, which reduces sulphates. 

From some reports, it is known that some SRB (such as Desulphovibrio desul-phuricans [58] and Desulphovibrio gracillis [59]) are capable of reducing nitrate. Excluding such weird SRBs, some methods have been proposed and exercised to use nitrate-reducing bacteria (NRB) against SRB. Two examples of these methods are, bio-competitive exclusion and bio-augmentation [60], The essential components of the definitions of these methods [60] are schematically presented as Figure 9.8. 

Desulphovibrio, usually under anaerobic conditions. In soils subject... 

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