Thiobacillus ferrooxidans

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.

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. 

Torma, A. E. The role of Thiobacillus ferrooxidans in hydrometallurgical processes. Advances in Biochemical Engineering 1977, 6, 1-37. 

Fujii, M., Matayoshi, Y., Umeda, T., Matsubara, S., Fukunaga, K., and Nomura, Y., Research on Treatment by Thiobacillus ferrooxidans of Pickling and Plating Waste Waters at Steelworks, Nippon Steel Technical Report, 37 59 (1988)... 

Grishin, S. I., and Tuovinen, O. H., Scanning Electron Microscopic Examination of Thiobacillus ferrooxidans on Different Support Matrix Materials in Packed Bed and Fluidized Bed Bioreactors, Appl. Microbiol. Biotechnol., 31 505 (1989)... 

Finally, whereas most laboratory experiments have been conducted in largely abiotic environments, the action of bacteria may control reaction rates in nature (e.g., Chapelle, 2001). In the production of acid drainage (see Chapter 31), for example, bacteria such as Thiobacillus ferrooxidans control the rate at which pyrite (FeS2) oxidizes (Taylor et al., 1984 Okereke and Stevens 1991). Laboratory ob-... 

Okereke, A. and S. E. Stevens, Jr., 1991, Kinetics of iron oxidation by Thiobacillus ferrooxidans. Applied and Environmental Microbiology 57,1052-1056. 

The ability of the chemolithoautotrophic bacteria Thiobacillus ferrooxidans to oxidize Fe has already been utilized for construction of a microbial sensor for the determination of iron [101]. The limit of determination of this biosensor is 60 pmol 1" with a response time ranging from 30 s to 5 min, depending on the Fe +-concentration in the sample. 

Nemati, M. and Webb, C., Effect of ferrous iron concentration on the catalytic activity of immobilized cells of Thiobacillus ferrooxidans, Appl. Microbiol. Biotechnol. 1996 vol. 46, no. 3, pp. 250-255. 

However chemical methods of mercury detoxification are far from adequate. It has become evident that mercury can be solubilized from HgS under conditions that could be present in a landfill. We have demonstrated chemical solubilization followed by volatilization with Fe2(S04)3, a product of oxidation of FeS04 (pyrite) by Thiobacillus ferrooxidans (data not shown). Other researchers have indicated that T. ferrooxidans can facilitate solubilization and volatilization of Hg° from HgS. Growth of T. ferrooxidans in the presence of cinnabar (mercury ore-contains HgS and some impurities) by Silver and Torma (1984) resulted in dissolved mercury concentration in the bioreactor of 64 mg/L (the form of Hg was not given). In similar experiments with T. ferrooxidans and cinnabar, Baldi and Olson (1987) did not... 

Baldi, F. and G. J. Olson. 1987. Effect of cinnabar pyrite oxidation by Thiobacillus ferrooxidans and cinnabar mobilization by a mercury-resistant strain. Appl. Environ. Microbiol. 53 772-776. 

Olson, G. J., F. D. Porter, J. Rubinstein, and S. Silver. 1982. Mercuric reductase from a mercury-volatilizing strain of Thiobacillus ferrooxidans. J. Bacteriol. 151 (3) 1230-1236. 

Silver, M. and A. E. Torma. 1974. Oxidation of metal sulfides by Thiobacillus ferrooxidans grown on different substrates Can. J. Microbiol. 20 141-147. 

The "iron bacterium" Thiobacillus ferrooxidans obtains energy from the oxidation of Fe2+ to Fe3+ with subsequent precipitation of ferric hydroxide (Eq. 18-23). However, it has been recognized recently that a previously unknown species of Archaea is much more important than T. ferrooxydans in catalysis of this reaction.3243... 

The other small blue proteins are only poorly characterized at present It is assumed their function is that of electron transfer. Rusticyanin from Thiobacillus ferrooxidans is thought to be the initial electron acceptor from iron(II) in the respiratory chain at pH 2. Rusticyanin contains 159 residues, with one cysteine, three methionine and five histidine residues. The protein is unusually stable at low pH, in accord with its presence in an acidophilic organism. The midpoint potential of rusticyanin is high (+680 mV), and is second in magnitude only to that of Polyporus laccase. 

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