Thiobacillus sulfur

Thiobacillus thiooxidans is an aerobic organism that oxidizes various sulfur-containing compounds to form sulfuric acid. These bacteria are sometimes found near the tops of tubercles (see Chap. 3, Tubercu-lation ). There is a symbiotic relationship between Thiobacillus and sulfate reducers Thiobacillus oxidizes sulfide to sulfate, whereas the sulfate reducers convert sulfide to sulfate. It is unclear to what extent Thiobacillus directly influences corrosion processes inside tubercles. It is more likely that they indirectly increase corrosion by accelerating sulfate-reducer activity deep in the tubercles. 

Fig. 6. Representative EPR spectra displayed by trinuclear and tetranucleEir iron-sulfur centers, (a) and (b) [3Fe-4S] + center in the NarH subunit of Escherichia coli nitrate reductase and the Ni-Fe hydrogenase fromD. gigas, respectively, (c) [4Fe-4S] + center in D. desulfuricans Norway ferredoxin I. (d) [4Fe-4S] center in Thiobacillus ferrooxidans ferredoxin. Experimental conditions temperature, 15 K microwave frequency, 9.330 GHz microwave power, (a) 100 mW, (b) 0.04 mW, (c) smd (d) 0.5 mW modulation amplitude (a), (c), (d) 0.5 mT, (b) 0.1 mT.

The colorless sulfur-oxidizing microorganisms include relatives of the bluegreen algae (Beggiaioa and Thiothrix) and a genus of the eubac-teria (Thiobacillus). The latter require iron for growth and presumably synthesize the cytochrome systems (60). 

More specifically, the invention involves the use of Thiobacillus denitrificans under anaerobic conditions to oxidize sulfur compounds such as hydrogen sulfide to sulfate. The process may be carried out in various ways such as in a batch or a continuous bioreactor system using a suspended or an immobilized biocatalyst. The method is particularly applicable to treating natural gas containing hydrogen sulfide and producing a biomass byproduct. 

The genus Thiobacillus, especially the species T. denitrificans catalyzed the oxidation reactions of hydrogen sulfide yielding soluble hydrosulfide compounds, elemental sulfur, and sulfuric acid. Carbonyl sulfide and carbon disulfide are converted to hydrogen sulfide by hydrolysis. Additionally, they are oxidized to SOx and sulfates via microbial action. The reported oxidation reactions of thiosulfate using nitrate as electron acceptor are ... 

In the biotechnological arena, a process for removing H2S and mercaptans from a hydrocarbon stream, such as a LPG, was disclosed [171]. Sulfide oxidizing microorganisms, such as those from the genera Thiobacillus and Thiomicrospira, are employed to convert H2S to sulfur and mercaptans to disulfides. First a weakly basic stream, (e.g., a sodium bicarbonate solution) is used to extract the sulfur molecules from the hydrocarbon stream using an ordinary extraction column. The extracted sulfur molecules are then... 

The aerobic bacteria responsible for this oxidation of hydrogen sulfide to sulfuric acid belong to the aerobic and autotrophic Thiobacillus family (Sand, 1987 Milde et al., 1983). These bacteria may be active at rather low pH values. Thiobacillus concretivorus is active at pH values between about 0.5 and 5 and may produce solutions of sulfuric acid up to about 7%. To be active, it requires that other species of the Thiobacillus family bring down the pH value. 

Two of the species, Thiobacillus concretivorus and Thiobacillus neapolitanus, are, in addition to sulfide, also able to use thiosulfate and elemental sulfur as energy sources. 

Aerobic The reactions carried out by Nitrosomonas and Nitrobacter (reactions b and c, autotrophic respectively) are known as nitrification, while those carried out by Beggiatoa and Thiobacillus thiooxidans (reactions d and e, respectively) are examples of sulfur oxidation ... 

Peck s hrst signihcant contribution was to look at Thiobacillus thioparus (the type species of the genus Thiobacillus) through the eyes of one who knew a lot about sulfate-reducing bacteria and about the enzymes involved in sulfate metabolism in yeast and mammalian tissues. This led him to think maybe the same enzymes are involved in sulfur oxidation as in reduction. The seminal paper of 1960 showed that this was indeed the case. 

It now seems probable that cleavage of thiosulfate in T. thioparus (and Thiobacillus denitrificans) depends not on a reductase as originally perceived by Peck (1960) but on a sulfur transferase of the rhodanese type (Peck 1968). Rhodanese is usually detected by its ability to transfer the sulfane-sulfur of thiosulfate to the nonphysiologic acceptor cyanide, producing thiocyanate and liberating sulfite ... 

Suzuki I. 1965b. Incorporation of atmospheric oxygen-18 into thiosulfate by the sulfur-oxidizing enzyme of Thiobacillus thiooxidans. Biochim Biophys Acta 110 97-101. 

Organisms such as Thiobacillus thiooxidans and Clostridium species have been linked to accelerated corrosion of mild steel. Aerobic Thiobacillus oxidizes various sulfur-containing compounds such as sulfides to sulfates. This process promotes a symbiotic relationship between Thiobacillus and sulfate-reducing bacteria. Also, Thiobacillus produces sulfuric acid as a metabolic by-product of sulfide oxidation. 

Because Thiobacillus feed on sulfur-containing compounds, they require other carbon-containing fuel to survive and multiply. Having a scaffold that can serve as a reservoir for nutrients could be an advantage, as opposed to the feed-and-starve cycle typically used. The team decided that the packing materials listed in Table 1.1 were not sufficient for the new biofilter design. 

Aerobic, chemolithotrophic bacteria. Colorless sulfur bacteria Thiobacillus iron or manganese-oxidizing bacteria, magnetotactic bacteria nitrifying bacteria Nitrobacter, Nitrosomonas... 

The sulfur-oxidizing bacteria. Anaerobic conditions prevail in marine sediments, in poorly stirred swamps, and around hydrothermal vents at the bottom of the sea. Sulfate-reducing bacteria form high concentrations (up to mM) of H2S (in equilibrium with HS and s2-)318-320 This provides the substrate for bacteria of the genus Thiobacillus, which are able to oxidize sulfide, elemental sulfur, thiosulfate, and sulfite to sulfate and live where the aerobic and anaerobic regions meet.311 321-323 Most of these small gram-negative... 

The oxidation and reduction of elemental sulfur and sulfide occur in different species of bacteria, e.g., the oxidation of sulfides via elemental sulfur to sulfate takes place in Chromaiia, the alternative oxidation to sulfate in Thiobacillus. The reduction of sulfate to sulfide occurs in Desiilfovibrio, The biosynthesis of organic sulfur compounds from sulfate takes place mainly in plants and bacteria, and the oxidation of these compounds to sulfate is characteristic of animal species and of heterotrophic bacteria. 

Rudimentary investigations of microbial desulfurization have received little attention in the literature at this time (2). One successful example of desulfurization is the removal of pyrite from coal by Thiobacillus sp. and Ferrobaccus sp. (3). While studies of the complex hydrocarbon-sulfur systems are of great value, being closer to in situ reality, investigation of a defined system should form the foundation of these more detailed studies. 

Hydrogen ion concentration (pH) was the second criterion by which growth of the bacilli was established. Sulfuric acid is a natural metabolic by-product of sulfur oxidation by the acidophillic Thiobacillus thiooxidans (5). As sulfur is used, acid is built-up in the medium thus lowering the pH. Studies in this laboratory have shown that the bacteria grow well in a pH as low as 0.5. 

Modified Waksman s medium was prepared in a Fernbach culture flask. An amount of organic sulfide normalized to an equivalent sulfur content of the standard medium (10 g/1.) was added followed by an emulsifier. The medium was then autoclaved for 30 min at 15 psi (121°C), or, as with the polysulfide and elemental sulfur, sterilization was achieved by membrane filtration. Upon cooling, the medium was inoculated with 10 cc of the pure strain of Thiobacillus thiooxidans. The culture s initial pH value was read, and an initial gravimetric sulfate assay was performed. Thereafter, pH and sulfate values were determined at two-day intervals for 25 days. 

Thiobacillus thiooxidans Aerobic acid producer that oxidizes various forms of sulfur to produce sulfuric acid (see reaction below), which in turn causes acid corrosion of steel. 

Sulfur bacteria Thiobacillus thiooxidans is an aerobic acid- and corrosion-producing sulfur bacterium. Thiothrix sp. are troublesome aerobic slime formers. The most prolific of the slime- and corrosion-producing sulfate-reducing bacteria (SRB) is the anaerobe Desulfovibrio desulfuricans. Other sulfur bacteria include the anaerobes Beggiatoa sp. and Clostridium migrificans. 

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