Thiosphaera pantotropha

Ammonium Alcaligenes latus Pseudomonas oleovorans Pseudomonas cepacia Ralstonia eutrophus Rhodobacter sphaeroides Speudomonas sp. K. Methylocystus oarvus Thiosphaera pantotropha Rhizobium ORS 571... 

Bell, L. C., and Ferguson, S. J. (1991). Nitric and nitrous oxide reductases are active under aerobic conditions in cells of Thiosphaera pantotropha. Biochem. J. 273, 423-427. 

Moir, W. B., Baratta, D., Richardson, D. J., and Ferguson, S. ]. (1993). The purification of a cd -type nitrite reductase from, and the absence of a copper-type nitrite reductase from, the aerobic denitrifier Thiosphaera pantotropha. Eur. J. Biochem. 212, 377-385. 

Cheesman, M., Ferguson, S. J., Moir, J. W. B., Richardson, D. J., Zumft, W. G., and Thomson, A. J., 1997, Two enzymes with a common function but different heme ligands. The optical and magnetic properties of the heme groups in the oxidised forms of nitrite reductase, cytochrome cdi, from Pseudomonas stutzeri and Thiosphaera pantotropha. Biochemistry 36 16267916276. 

Kobayashi, K., Koppenh fer, A., Ferguson, S. J., and Tagawa, S., 1997, Pulse radiolysis studies on cytochrome cd nitrite reductase from Thiosphaera pantotropha Evidence for a fast intramolecular electron transfer from c heme to d, heme, RiocAemtstry 36 1361 In 13616. 

Castignetti, D. (1990). Bioenergetic examination of the heterotrophic nitrifier-denitrifier Thiosphaera pantotropha. Antonie Van Leeuwenhoek International Journal of General and Molecular Microbiology 58, 283-289. 

Wehrfritz, J. M., ReiUy, A., Spiro, S., and Richardson, D.J. (1993). Purification of hydroxylamine oxidase from Thiosphaera pantotropha Identification of electron acceptors that couple heterotrophic nitrification to aerobic denitrification. FEES Letters 335, 246—250. 

Although the oxidation mechanism of nitrite to nitrate in the heterotrophic nitrifiers has not been known at all on the enzyme level, the oxidation mechanism of ammonia to nitrite has been partially clarified. Ammonia is oxidized to nitrite through hydroxylamine also in the heterotrophic bacteria. The oxidation of ammonia to hydroxylamine is catalyzed by ammonia monooxygenase as in the enzyme of Nitrosomonas europaea. The enzyme purified from Paracoccus pantotropha GB17 (formerly Thiosphaera pantotropha GB17 or Paracoccus denitrificans GB17) catalyzes the oxidation of ammonia to hydroxylamine and contains copper, but its activity is not inhibited by acetylene (Moir et al., 1996), unlike the enzyme of Nitrosomonas europaea. 

Robertson LA, Van Niel EWJ, Torremans RAM, Kuenen JG (1988) Simultaneous nitrification and denitrification in aerobic chemostat cultures of Thiosphaera pantotropha. Appl Environ Microbiol 54 2812-2818... 

Wehrfritz J-M, Carter JP, Soiro S, Richardson DJ (1997) Hydroxylamine oxidation in heterotro-phic nitrate-reducing soil bacteria and purification of hydroxylamine cytochrome c oxidore-ductase from Pseudomonas species. Arch Microbiol 166 421 —424 Wehrfritz J-M, Reilly A, Spiro S, Richardson DJ (1993) Purification of hydroxylamine oxidase from Thiosphaera pantotropha. Identification of electron acceptors that couple heterotrophic nitrification to aerobic denitrification. FEBS Lett 335 246-250 Wetzstein H-G, Ferguson SJ (1985) Respiration-dependent proton translocation and the mechanism of proton motive force generation in Nitrobacter winogradskyi. FEMS Microbiol Lett 30 87-92... 

The bacterium Thiosphaera pantotropha is one such, and is about as far removed as we can get from our sense of an evolutionary pinnacle it lives on faeces. Originally isolated in 1983 from an effluent-treatment plant, it applies an extraordinary virtuosity to the extraction of energy from sewage. 

There are two main types of NiRs involved in the reduction of nitrites, namely, the heme-containing cytochrome cdj NiR which was obtained and first purified from Thiosphaera pantotropha (261). The second kind of NiR is the copper-containing NiR which was first isolated from Alcaligenes xylosoxidans NCIB 11015, a bacterial isolated from a soil in Japan. Other Cu NiR have been isolated from, Achromohacter cycloclastes, Alcaligenes faecalis S-6, Bacillus halodenitrificans, Haloferax denitrificans, Nitrosomonas europaea, Pseudomonas aureofaciens, Rhodobacter sphaeroides, and Hyphomicrobium sp. (262 and references thereinj. In mammalian systems, nitrites are reduced by deoxyHb (263) and by ferrous myoglobin (264,265) to nitric oxide. In synthetic iron porphyrins. Ford and coworkers have demonstrated how nitrites inhibit the reductive nitrosylation process by forming ferric-nitrites species (266). 

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