Arsenite oxidation

Oremland RS, SE Hoeft, JM Santini, N Bano, RA Hollibaugh, JT Hollibaugh (2002) Anaerobic oxidation of arsenite in Mono Lake water and by a facultative, arsenite-oxidizing chemoauthotroph strain MLHE-1. Appl Environ Microbiol 68 4795-4802. 

Santini JM, LI Sly, RD Schnagl, JM Macy (2000) A new chemolithoautotrophic arsenite-oxidizing bacterium isolated from a gold mine phylogenetic, physiological and preliminary biochemical studies. Appl Environ Microbiol 66 92-97. 

Power et al. (2005) show the effeet of pH and initial As(III) coneentration on the kineties of arsenite oxidation at bimessite-water interfaees, when a competitive metal (e.g., Zn) is present in an adsorbed or nonadsorbed state (Fig. 16.5). Two well-defined trends in the As(III) oxidation reactions can be distinguished (1) the extent of As(III) oxidation decreases with increasing pH from 4.5 to 6.0 and (2) oxidation on a percent basis is suppressed with increasing initial As(III) concentration from 100 to 300 dM. The pH effects on As(III) oxidation may have been influenced by competitive adsorption reactions between As(III) and reaction products (e.g., Mn(II)) and were not influenced by arsenic solution speciation. The suppressed As(III) oxidation rate constant may be a result of differences in the amount of Mn(II) release, which compete with dissolved As(III) species for unreacted Mn(IV) surface sites, and of Mn(II) adsorption, which inhibit the reaction between As(III) and Mn(IV) surface sites. 

Fig. 16.5 Percent of dissolved As(lll), As(V)(3,j, and adsorbed As during As(III) oxidation kinetics on bimessite (suspension density 0.1 g Lin 0.01 M NaCl, and atmosphere) as a function of pH and initial As(lll) concentration, [As(lll)].. (a) pH 4.5, [As(lll)]. = lOOpM (b) pH 4.5, [As(III)]. = 300pM (c) pH 6.0, [As(lll)]. = lOOpM (d) pH 6.0, [As(lll)]. = 300pM. Reprinted with permission from Power LE, Arai Y, Sparks DL (2005) Zinc adsorption effect on arsenite oxidation kinetics at the bimessite water interface. Environ Sci Technol 39 181-187. Copyright 2005 American Chemical Society...

Gihring, T. M., Druschel, G. K., McCleskey, R. B., Hamers, R. J. Banfield, J. F. 2001. Rapid arsenite oxidation by Thermus aquaticus and Thermus thermophilus Field and laboratory investigations. Environmental Science and Technology, 35, 3857-3862. 

Pettine, M., Campanella, L. and Millero, F.J. (1999) Arsenite oxidation by H202 in aqueous solutions. Geochimica et Cosmochimica Acta, 63(18), 2727-35. 

Santini, J.M., Vanden Hoven, R.N. and Macy, J.M. (2002) Characteristics of newly discovered arsenite-oxidizing bacteria, in Environmental Chemistry of Arsenic (ed. W.T. Frankenberger Jr.), Marcel Dekker, New York, pp. 329-42. 

Xu, T., Kamat, P.V. and O Shea, K.E. (2005) Mechanistic evaluation of arsenite oxidation in Ti02 assisted photocatalysis. Journal of Physical Chemistry A, 109(40), 9070-75. 

Potassium iodide solution in the presence of concentrated hydrochloric acid, iodine is precipitated upon shaking the mixture with 1-2 ml of chloroform or of carbon tetrachloride, the latter is coloured blue by the iodine. The reaction may be used for the detection of arsenate in the presence of arsenite oxidizing agents must be absent. 

Oremland, R. S., Hoeft, S. E., Santini, J. M. et al. (2002a). Anaerobic oxidation of arsenite in Mono Lake water by a facultative arsenite oxidizing chemoautotroph, strain MLHE-1. Applied and Environmental Microbiology, 68, 4795-802. 

FIGURE 72.2. Arsenic detoxification mechanisms (reduction, oxidation, methylation, and resistance) in prokaryotes. (A) Respiratory arsenate reductase (Arr) is involved in the reduction of As(V) by the dissimilatory arsenate respiring organisms. (B) Arsenite oxidase (Aox/Aso) is responsible for oxidation of As(III) by chemoautotrophic or heterotrophic arsenite oxidizers. 

Alcaligenes faecalis and five members of the p Proteobacteria are heterotrophic arsenite oxidizers, whereas Pseudomonas arsenitoxidans and NT-26 grew anaerobically through chemoautotrophic oxidation (Oremland and Stolz, 2005 Santini et al, 2000). However, six members of a Proteobacteria (Ben-5, NT-3, NT-4, NT-2, NT-26, and NT-25) and one member of y Proteobacteria (MLHE-1) were known chemohthoautotrophic arsenite oxidizers (Oremland et al, 2002). The best characterized and probably most studied of aU arsenite oxidizers is Alcaligenes faecalis, a heterotrophic arsenite oxidizer (Osborne and Enrlich, 1976). The arsenite oxidase from Alcaligenes faecalis has been purified and structurally characterized (Ellis et al, 2001). A similar enzyme has also been purified from the heterotrophic arsenite oxidizers Hydrogenophaga sp. strain NT-14 (Vanden Hoven and Santini, 2004) and the chemolithoautotrophic Rhizobium sp. strain NT-26 (Santini and Vanden Hoven, 2004), which indicate that the arsenite oxidase enzyme is also a member of the DMSO reductase family of molybdenum enzymes, similar to the respiratory arsenate reductases (Arr). The arsenite oxidase heterodimer comprises an 88 kDa catalytic subunit encoded by the aoxB gene that contains a [3Fe-4S] cluster and molybdenum bound to the pyranopterin cofactor and a 14 kDa subunit... 

TABLE 72.2. Arsenite oxidizing prokaryotes characterized at molecular level... 

M. C., Boimefoy, V. (2008). Arsenite oxidation by a chemoau-tofrophic moderately acidophilic Thiomonas sp. from the strain isolation to the gene study. Environ. Microbiol. 10 228-37. 

Gihring, T.M., Banfield, J.F. (2001). Arsenite oxidation and arsenate respiration by a new Thermus isolate. FEMS Microbiol. Lett. 204 335-40. 

Rhine, E.D., Ni Chadhain, S.M., Zylstra, G.J., Young, L.Y. (2007). The arsenite oxidase genes (aroAB) in novel chemoautotrophic arsenite oxidizers. Biochem. Biophys. Res. Commun. 354 662-1. 

Vanden Hoven, R.N., Santini, J.M. (2004). Arsenite oxidation by the heterotroph Hydrogenophaga sp. str. NT-14 the arsenite oxidase and its physiological electron acceptor. Biochim. Biophys. Acta (BBA) - Bioenergetics 1656 148-55. 

Kinetics of the arsenite oxidation in seepage water from a tin mill tailings pond. Talanta 51, 1087—1095. 

Arsenic is a metalloid, which forms a number of toxic compounds, and the most toxic is arsenite oxide, AS2O3. This As " " is absorbed through the lungs and intestines. In biochemical processes. As acts to coagulate proteins, forms complexes with coenzymes, and inhibits the production of adenosite triphosphate (ATP) in essential metabolic reactions. 

M Pettine, L Campanella, El MiUero. Arsenite oxidation by H2O2 in aqueous solutions. Geochim Cosmochim Acta 63 2727-2735, 1999. 

N Wakao, H Koyatsu, Y Komai, H Shimokawara, Y Sakurai, H Shiota. Microbial oxidation of arsenite and occurrence of arsenite-oxidizing bacteria in acid mine water from a sulfur-pyrite mine. Geomicrobiol 6 11-24, 1988. 

CR Jackson, H Langner, J Christiansen, WP Inskeep, TR McDermott. Molecular analysis of the microhial community involved in arsenite oxidation in an acidic, thermal spring. Microbiol Ecol, in press, 2001. 

In addition to plasmid arsenic resistance that is well understood and for which clusters of genes have been isolated and sequenced, there are bacterial arsenic metabolism systems that involve oxidation of arsenite to arsenic. Arsenite oxidation by aerobic pseudomonads was first found with bacteria isolated from cattle dipping solutions where arsenicals were used as agents against ticks around the time of World War I. They were subsequently isolated by Turner and Legge... 

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