Bacteria arsenite-oxidizing

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. 

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. 

Characteristics of Newly Discovered Arsenite-Oxidizing Bacteria... 

This chapter concentrates on arsenite oxidation by NT-26 as well as a number of other recently isolated arsenite-oxidizing bacteria. It will be apparent that all but one of these organisms is phylogenetically distinct from the arsenite oxidizers previously identified. The isolation, phytogeny, physiology, and biochemistry of arsenite oxidation are described. 

For the isolation of arsenite-oxidizing bacteria, samples were taken from two different gold mine sites in Australia (13). Moist samples of arsenopyrite (FeAsS)... 

The phylogenetic analysis of 16S rRNA gene sequences of the above-mentioned arsenite-oxidizing bacteria showed that they were dispersed in either the a-Pro-teobacteria (Fig. 2) or the P-Proteobacteria (Fig. 3) (13). 

Six of the 11 arsenite-oxidizing bacteria (all members of the a-Proteobacteria) were able to grow chemolithoautotrophically (i.e., aerobically in a minimal salts medium with arsenite as the electron donor and carbon dioxide-bicarbonate as the sole carbon source) (Table 1) (13). The time required for these bacteria to oxidize 5 mM arsenite varied from 3 days (for NT-25 and NT-26) to more than 5 days (for BEN-5). The arsenite was oxidized to an equivalent amount of arsenate and the pH of the medium decreased from 8.0 to 6.5. For all of the abovemen-tioned bacteria, no growth occurs in the absence of arsenite (i.e., only in an aerobic minimal salts medium containing carbon dioxide-bicarbonate). 

Table 1 Comparisons of Chemolithoautotrophic Arsenite-Oxidizing Ability of Newly Isolated Arsenite-Oxidizing Bacteria with A. faecalis HLE...

Table 2 Comparisons of Optimum Buffer, pH, and Cellular Location of Arsenite Oxidases from Different Arsenite-Oxidizing Bacteria...

The discovery of six new chemolithoautotrophic arsenite-oxidizing bacteria isolated from gold mines in different regions of Australia demonstrates that energy... 

The chemolithoautotrophic arsenite-oxidizing bacteria described in this... 

JM Santini, LI Sly, A Wen, P Durand, D Comrie, JM Macy. New arsenite-oxidizing bacteria isolated from Australian gold-mining enviromnents Phylogenetic relationship. Geomicrobiology J, in press. 

Arsenate resistance in some bacteria occurs via an ars operon that encodes proteins involved in arsenate reduction to arsenite, and ATP-dependent efflux of arsenite (25-29). The presence of this system has not been demonsttated in arsenite-oxidizing bacteria. 

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