Thiobacillus

Acid producers. Many bacteria produce acids. Acids may be organic or inorganic depending on the specific bacterium. In either case, the acids produced lower the pH, usually accelerating attack. Although many kinds of bacteria may generate acids, Thiobacillus thiooxidans and Clostridium species have most often been linked to accelerated corrosion on steel. 

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. 

MV Botuyan, A Toy-Palmer, J Chung, RC Blake II, P Beroza, DA Case. NMR solution structure of Cu(I) rusticyanm from Thiobacillus feiTooxidans Structural basis of the extreme acid stability and redox potential. J Mol Biol 263 752-767, 1996. 

Gram negative Bacteria cells which lose the crystal violet during the decolorizing step and are then colored by the counterstain. Pseudomonas and Thiobacillus are examples of gram negative strains. 

The resulting environment is low in pH and extremely corrosive. Thiobacillus and Beggiatoa are good examples of this form of bacteria. 

Fig. 2.19 Thiobacillus thio-oxidans (NCIB 8 342). Usually stubby rods, but a few elongated forms can be seen (these are most common in old cultures), x 260 (Crown copyright courtesy Microbiological Research Establishment)...

F. ferro-oxidants is capable of accelerating the oxidation of pyritic (FeSj) deposits at acid pH values. It is usually found in association with Thio-bacillus and was known as Thiobacillus ferroxidans before the distinction between the two organisms was appreciated. It is responsible for pollution problems arising from acid waters in gold and bituminous coal mines such waters are corrosive to pumping machinery and mining installations (see Fig. 2.20). 

Moreover, decomposition may also be caused by bacterial action (e.g. Thiobacillus thioparus), particularly if the solution has been standing for some time. For these reasons, the following recommendations are made ... 

Thiobacillus ferrooxidans function. 6, 651 Rhus vernicifera stellacyanin structure, 6,651 Riboflavin 5 -phosphate zinc complexes, 5,958 Ribonucleotide reductases cobalt, 6,642 iron, 6,634... 

To date, only two exceptions to the pK of 8 rule have been found the Rieske protein from Sulfolobus acidocaldarius (139) and that from Thiobacillus ferrooxidans (140). In both cases, a first pK is observed in the vicinity of 6 (Fig. 7). The fact that Sulfolobus and Thiobacillus are phylogenetically almost as distant as they can possibly be, but share acidophilic growth conditions (medium-pH of 2), indicates that the pK, which is lower by 2 pH units in Sulfolobus and Thiobacillus, reflects adaptation. In the absence of structural information for the two acidophilic Rieske proteins, the molecular modifications resulting in this pK shift are difficult to guess. The absence of sequence data for the Thiobacillus protein furthermore precludes a comparative approach. It seems likely, however, that the solvent-exposed histidine ligands to the cluster will become slightly more bur-... 

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.

Katayama Y, Y Matsushita, M Kaneko, M Kondo, T Mizuno, H Nyunoya (1998) Cloning of genes coding for the three subunits of thiocyanate hydrolase of Thiobacillus thioparus THI 115 and their evolutionary relationships to nitrile hydratase. J Bacterial 180 2583-2589. 

Strains of some facultatively heterotrophic and methylotrophic bacteria can use CS2 as sole energy source, and under aerobic conditions also COS, dimethyl sulfide, dimethyl disulfide, and thioacetate (Jordan et al. 1995). It was proposed that the strains belonged to the genus Thiobacillus, though they are clearly distinct from previously described species, and they have now been assigned to Paracoccus denitrificans (Jordan et al. 1997). 

In the leaching process, bacteria such as Thiobacillus ferroxidans and those belonging to the Sulfolobus genera, play a major role in the oxidation reactions at moderate and higher temperatures respectively. The oxidation of sulfides by bacteria is typified by the reactions of pyrite, a common accessory mineral in primary copper ore bodies this reaction can be considered to proceed through two stages ... 

Some metals can be converted to a less toxic form through enzyme detoxification. The most well-described example of this mechanism is the mercury resistance system, which occurs in S. aureus,43 Bacillus sp.,44 E. coli,45 Streptomyces lividans,46 and Thiobacillus ferrooxidans 47 The mer operon in these bacteria includes two different metal resistance mechanisms.48 MerA employs an enzyme detoxification approach as it encodes a mercury reductase, which converts the divalent mercury cation into elemental mercury 49 Elemental mercury is more stable and less toxic than the divalent cation. Other genes in the operon encode membrane proteins that are involved in the active transport of elemental mercury out of the cell.50 52... 

Inoue, C., Sugawara, K., and Kusano, T., Thiobacillus ferrooxidans mer operon Sequence analysis of the promoter and adjacent genes, Gene, 96 (1), 115-120, 1990. 

Adoki, A., Influence of divalent metal ions on degradation of dimethylsulphide by intact cells of Thiobacillus thioparus TK-m, Afr J Biotechnol, 6 (11), 1343-1347, 2007. 

Kanagawa T, Mikami E. 1989. Removal of methanethiol, dimethyl sulfide, dimethyl disulfide, and hydrogen sulfide from contaminated air by Thiobacillus thioparus TK-m. Appl Environ Microbiol 55(3) 555-558. 

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). 

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