Assessment of arsenic resistance and removal by Pseudomonas sp. ASR3 isolated from arsenic-enriched water sources

摘要

Arsenic (As) occurs in the environment in several forms but in natural waters, it is mostly found as trivalent arsenite [As(Ⅲ)] or pentavalent arsenate [As (V)]. Arsenate generally is the dominant form in oxic waters. In contrast, arsenite dominates in sulfidic and methanic waters including most geo-thermal water. Both forms are toxic; comparatively arsenite is the most toxic forms (Welch et al., 2006). While As is a well-known poison, a number of taxo-nomically diverse microorganisms have evolved biochemical mechanisms that involve intracellular reduction of arsenate to arsenite followed by efflux of the arsenite (Broeer et al., 1993, Raja et al., 2006). Pseudomonas fluorescens has been reported as active reducer under aerobic conditions (Ehrlich, 2008). Patel et al., (2007) reported reduction of arsenate to arsenite by Pseudomanas hypertoler-ant to As. Likewise, microorganisms and microbial products have been reported to efficiently remove soluble and particulate forms of metals, especially from dilute solutions, through bioaccumulation and therefore microbe-based technologies provide an alternative to the conventional techniques of metal removal/recovery (Ozdemir et al., 2004).