Thiobacilli

Estimation The above medium is reinforced with lOg/i of thiocyanate, sulphur is omitted and it is prepared as pour plates by the addition of 3% agar. Organisms other than Thiobacilli will grow from spread samples, but the Thiobacilli are easily distinguished by sulphur haloes (see Fig. 2.19). 

Mechanism and sulphur oxidation Apart from its intrinsic interest the economic importance of acid corrosion and more lately interest in ore leaching, has stimulated considerable work on the oxidation of sulphur, Fe and Mn. It must be stressed that the Thiobacilli are obligate aerobes, i.e. that depend on molecular oxygen as a terminal electron acceptor. Possible reactions for the oxidation of sulphur are... 

Facultatively heterotrophic thiobacilli that use a number of organic sulfur compounds as energy source... 

The microorganisms reduce the nitrate and produce sulfuric acid, which eventually dissolves the rock formation, thus releasing oil. The microorganisms can be denitrifying thiobacilli, such as T. denitrificans [1667]. 

Milde, K., W. Sand, W. Wolf, and E. Bock (1983), Thiobacilli of the corroded concrete walls of the Hamburg sewer system,/. General Microbiology, 129, 1327-1333. 

Sand, W. (1987), Importance of hydrogen sulfide, thiosulfate and methylmercaptan for growth of thiobacilli during simulation of concrete corrosion, Applied and Environmental Microbiology, 53(7), 1645-1648. 

Although these equations held true for some strains of bacteria under some growth conditions, they did not help explain the commonly observed quantitative conversion of both sulfur atoms of thiosulfate to sulfate, rather than the liberation of the sulfane-sulfur mainly as elemental sulfur. During the 1960s, cyclic reactions of polythionates and other polysulfur compounds continued to be postulated as mechanisms for thiosulfate and polythionate metabolism (Trudinger 1967), but none of these was supported at the time by strong biochemical evidence. The time was opportune for a new approach to the problem of thiosulfate oxidation in thiobacilli. 

Oxidation of the Sulfane-Sulfur of Thiosulfate and the Resynthesis of the Sulfonate Group of Thiosulfate from Sulfane-Sulfur by Thiobacilli... 

Suzuki I, Silver M. 1966. The initial product and properties of the sulfur-oxidizing enzyme of thiobacilli. Biochim Biophys Acta 122 22-33. 

Trudinger PA. 1967. The metabolism of inorganic sulphur compounds by thiobacilli. Rev Pure Appl Chem 17 1-24. 

FeOOH) indicated that a Clostridium species released 55% of the coprecipitated nickel after 40 hours. Similarly, precipitated nickel sulfides in sediment can be mobilized through sulfur oxidation by Thiobacilli (Wood 1987). In this case, the oxidized sulfur may produce H2SO4 and decrease the pH. 

Aerobic microbial oxidation Beggiatoa mat Coastal marine sediment Coastal marine sediment Estuarine sediments Thiobacilli in water of L. Faro S oxidation in water of Big Soda L, Chemical oxidation by oxygen0 Black Sea Calculated Hypolimnetic Sediment... 

A few mechanisms were postulated for this reaction (6). No matter what mechanism is considered, the oxidation of elemental sulfur or thiosulfate is accompanied by reductive cleavage of the sulfur-sulfur bridges. In the case of sulfur, the intermediate involved is a cyclic form of sulfur, probably Ss, although there is little difference observed for different allotrophic forms of sulfur such as rhombic, precipitated, and amphorous. These cyclic sulfides form the basis of polysulfanes and polythionates which could be metabolized readily by Thiobacilli (as shown in Figure 3). Actually, sulfur oxidation begins with its reduction, in which the gluathione-sulfhydryl groups located near the cell surface take part ... 

Figure 3. Summary of DMS transformations. 1) aerobic and anaerobic bacteria 2) chemical and probably biochemical oxidation 3) aerobic and anaerobic bacteria 4) thiol S-methyltransferase S) sulfate reducers and methanogens 6) aerobic bacteria (hyphomicrobia and thiobacilli) 7) chemical and biochemical (aerobic and anaerobic) 8) chloroperoxidase 9) mechanism unknown 10) aerobic and anaerobic bacteria.

Bacteria of the genus Thiobacillus, obtain energy not by oxidation of organic compounds, but by oxidation of inorganic sulfur compounds (including sulfides) to sulfuric acid. The following reactions are performed by mixed cultures of Thiobacilli... 

One final consideration when storing solid sulfur is the almost inevitable presence of sulfuric acid. Sulfur can become naturally contaminated with sulfuric acid through the presence of thiobacilli thiooxidans3 or continuous exposure to direct sunlight.4 Recent research has demonstrated the short-term effectiveness of certain bactericides in delaying bacterial colonization. Nevertheless, discrete pockets of weak (highly corrosive) sulfuric acid should always be presumed to exist within a sulfur storage pile. Hydrochloric acid, which may also be present when solid sulfur has been transported by vessel,5 must be neutralized to avoid potentially disastrous corrosion of downstream equipment. 

Harrison, A. P. 1984. The acidophilic thiobacilli and other acidophilic bacteria that share their habitat. Annu. Rev. Microbio. 38 265-292. 

Shell Paques A version of the THIOPAQ process for removing H2S from gas streams by use of natural bacteria (Thiobacilli). It was awarded a prize by IChemE in 2002. 

Thiamine pirophosphate, lipoamide dehydrogenase and, 126 Thiobacilli, adenylyl sulfate reductases in, 282... 

This family includes the sulfite oxidases and dehydrogenases of prokaryotes Thiobacilli sp.), plants, birds, and animals, and the assimilatory nitrate reductases from bacteria, algae, fungi, and plants. The sulfite oxidases of higher eukaryotes are 100-110kDa homodimers (Table 1) they are located in the mitochrondrial intermembrane space and catalyze the oxidation of toxic sulfite to innocuous sulfate (equation 7). Human sulfite oxidase deficiency leads to major neurological abnormalities, mental retardation, dislocation of the ocular lenses, and early death. ... 

The thiobacilli are autotrophs that produce sulfate (or H2SO4) directly from the oxidation of H2S, the gas that may be produced by other bacteria or by volcanic emanations. Other bacteria, and including some Archea, may accumulate elemental S° when H2S is in short supply, and... 

Aminuddin M. and Nicholas D. J. D. (1974) Electron transfer during sulfide to sulfite oxidation in Thiobacillis denitrifi-cans. J. Gen. Microbiol. 82, 115-123. 

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