Desulfovibrio species, anaerobic

Soluble proteins containing b-type hemes have not been detected in anaerobes, with the exception of catalase all other examples of b-type cytochromes known so far are membrane-associated. A catalase was isolated from D. vulgaris [87], and its activity has also been detected in other strains of Desulfovibrio species. Superoxide dismutase activities have also been detected in these bacteria [87]. As mentioned in the introduction, the finding of catalase and superoxide dismutase in an anaerobe is puzzling. It is not known whether these enzymes are just used for detoxification or indicate the presence of adaptation capabilities to oxygenic environments. 

The taxonomy of the formation and river water samples (Table 13) showed a typical cross section of aerobic bacteria associated with soil and water. Three genera predominated Bacillus, Pseudomonas, and Arthrobacter. Anaerobic sulfate reducers were found only in the formation water sample but constituted 40 percent of the isolates from this source. Four of the five sulfate reducing isolates were Desulfovibrio species one was Desulfotomaculum spe-... 

Bacterial anaerobes including Desulfovibrio, Desulfomonas, and Desulfotomaculum are known sulfate-reducing species. They can survive in fresh, brackish, and sea water and are present in most soils and sediments containing sulfate and sulfite compounds. Enzymes which promote the conversion of sulfates and sulfites to metal sulfides through chemical reduction are present in these bacteria. Iron sulfide, FeS, is a product of this process. 

Deposition of elemental sulphur formed from sulphate Essential collaboration of at least two different microbial species occurs in the transformation of sulphate to S° in salt domes or similar sedimentary formations (see Ivanov, 1968). This transformation is dependent on the interaction of a sulphate reducer like Desulfovibrio desulfuricans, which transforms sulphate to H2S in its anaerobic respiratory metabolism, and an H2S oxidizer like Thiobacillus thioparus, which, under conditions of limited O2 availability, transforms H2S to S° in its respiratory metabolism (van den Ende van Gemerden, 1993). The collaboration of these two physiological types of bacteria is obligatory in forming S° from sulphate because sulphate reducers cannot form S° from sulphate, even as a metabolic intermediate. It should be noted, however, that the sulphate reducers and H2S oxidizers are able to live completely independent of each other as long as the overall formation of S° from sulphate is not a requirement. 

Sulfate reducers, originally identified as the bacterial species—desulfovibrio, desulfomaculum, and desulfomonas— have restricted nutrition unable to degrade organic materials below acetate. Recent investigations have vastly expanded the number of species that anaerobically use aliphatic, aromatic, and heterocyclic organic molecules, and some use H2 as an energy source to reduce sulfate. 

This has been attributed to the anaerobic respiration by microorganisms like Desulfovibrio in seep sediments (Aharon, 2000) they use the abundant reduced carbon forms as electron donors and seawater-derived S042 as an electron acceptor. In addition to H2S, this metabolism can also produce carbonate species and ammonia whose concentration and type depend on the nature of the reduced carbon substrates and on the buffering capacity of the environment. Sulphate and H2S often show a linear, inverse relationship in profiles of seep sediment pore fluids, further indicating the link between sulphate reduction and H2S production (Aharon, 2000). 

The heme c nitrite reductase was isolated from anaerobes or facultative anaerobes like Desulfovibrio desulfuricans (ATCC 27774) [128], Wolinella suc-cinogenes [129], Escherichia coli [130], two Vibrio species [131,132] and Sulfurospirillum deleyianum [133]. In D. desulfuricans (ATCC 27774), W. succi-nogenes and S.deleyianum the enzyme is membrane-bound, and in the other cases it was isolated from the soluble fraction. 

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