Arsenic accumulation by Pseudomonas stutzeri and its response to some thiol chelators

Abstract

Objective The aim of this study is to examine arsenic accumulation by Pseudomonas stutzeri and its response to some thiol chelators, DMPS and MiADMSA. MethodsDetermination of arsenic accumulation by Pseudomonas sp. was carried out using an atomic absorption spectrophotometer, a TEM and an EDAX. Arsenate reductase enzyme assay was carried out from a cell-free extract of Pseudomonas sp. The effect of chelating agents on arsenite accumulation was analyzed. Total cellular proteins were analyzed using 1-D SDS-PAGE. Results Pseudomonas sp. exhibited a maximum accumulation of 4 mg As g -1 (dry weight). TEM and EDAX analysis showed the presence of As-containing electrondense particles inside the cells. Data on arsenate reductase enzyme kinetics yielded a K m of 0.40 mM for arsenate and a V max of 5,952 lmol arsenate reduced per minute per milligram of protein. The chelating agents MiADMSA and DMPS were found to reduce the arsenic accumulation by 60 and 35%, respectively, whereas the presence of both chelating agents in medium containing cells pretreated with arsenite reduced it by up to 90%. The total protein profile of the cellular extract, obtained by 1-D SDS-PAGE, indicated five upregulated proteins, and three of these proteins exhibited differential expression when the cells were grown with MiADMSA and DMPS. Conclusion This study shows a new approach towards arsenic detoxification. A combination treatment with MiADMSA and DMPS may be useful for removing intracellular arsenic. The proteins that were found to be induced in this study may play an important role in the extrusion of arsenic from the cells, and this requires further characterization.

Arsenate reduction and mobilization in the presence of indigenous aerobic bacteria obtained from high arsenic aquifers of the Hetao basin, Inner Mongolia

“…Joshi et al (2008) found that, compared with the growth in the medium with the absence of As, the strain growth in the media with 50 mM As(V) or 0.2 mM As(III) decreased by 43% and 56%. Liao et al (2011) found that, under aerobic conditions on MSM agar plates, the lowest As(III) concentration that Table 2 The primer sequences used for the PCR of arrA gene and ars genes.…”

“…Other study showed that the P. stutzeri strain As-1 isolated in the laboratory grew in a culture medium with 50 mM As(V) or 0.2 mM As(III) (Joshi et al, 2008). Joshi et al (2008) found that, compared with the growth in the medium with the absence of As, the strain growth in the media with 50 mM As(V) or 0.2 mM As(III) decreased by 43% and 56%.…”

Comparison of arsenate reduction and release by three As(V)-reducing bacteria isolated from arsenic-contaminated soil of Inner Mongolia, China

“…The strains could tolerate As(Ⅴ) at varying concentrations from 30 to 50 mM or As(Ⅲ) from 10 to 15 mM. Joshi et al (2008) found that the growth of the isolated strain As-1 (P. stutzeri) was inhibited in the medium with 50 mM As(Ⅴ) or 0.2 mM As(Ⅲ) (Joshi et al, 2008). In this study, strain JQ could tolerate 60 mM As(Ⅴ) or 16 mM As(Ⅲ), strain DJ-3 could tolerate more than 60 mM As(Ⅴ) or 8 mM As(Ⅲ), indicating that the strains in our study had a relatively stronger resistance to As than other strains.…”

Integrated phytobial remediation for sustainable management of arsenic in soil and water

“…The volatile arsines in air have short life span and their quick oxidation again contribute to soil and water pool of As(III)/As(V). In addition to biotransformation many microbes have been found in nature that bioaccumulate large amount of As Joshi et al, 2008;Xie et al, 2013a, Tripathi et al, 2007.…”