Global Molecular and Morphological Effects of 24-Hour Chromium(VI) Exposure on Shewanella oneidensis MR-1

Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
Applied and Environmental Microbiology (Impact Factor: 3.67). 10/2006; 72(9):6331-44. DOI: 10.1128/AEM.00813-06
Source: PubMed


The biological impact of 24-h ("chronic") chromium(VI) [Cr(VI) or chromate] exposure on Shewanella oneidensis MR-1 was assessed by analyzing cellular morphology as well as genome-wide differential gene and protein expression profiles. Cells challenged aerobically with an initial chromate concentration of 0.3 mM in complex growth medium were compared to untreated control cells grown in the absence of chromate. At the 24-h time point at which cells were harvested for transcriptome and proteome analyses, no residual Cr(VI) was detected in the culture supernatant, thus suggesting the complete uptake and/or reduction of this metal by cells. In contrast to the untreated control cells, Cr(VI)-exposed cells formed apparently aseptate, nonmotile filaments that tended to aggregate. Transcriptome profiling and mass spectrometry-based proteomic characterization revealed that the principal molecular response to 24-h Cr(VI) exposure was the induction of prophage-related genes and their encoded products as well as a number of functionally undefined hypothetical genes that were located within the integrated phage regions of the MR-1 genome. In addition, genes with annotated functions in DNA metabolism, cell division, biosynthesis and degradation of the murein (peptidoglycan) sacculus, membrane response, and general environmental stress protection were upregulated, while genes encoding chemotaxis, motility, and transport/binding proteins were largely repressed under conditions of 24-h chromate treatment.

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    • "l mass it takes longer period for chromate reduc - tion ( Chatterjee et al . , 2009 ; McLean et al . , 2000 ; Sau et al . , 2008 ) . At higher initial concentrations , Cr ( VI ) has been reported to decrease the growth rate of the bacterial cells , accompanied by morphological changes due to toxicity and chromate stress ( Ackerley et al . , 2006 ; Chourey et al . , 2006 ; Desai et al . , 2008 ) ."
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    ABSTRACT: The anthropogenic inputs of hexavalent chromium [Cr(VI)] have increased enormously during the past few decades and has become a challenge for life on earth and hence removal of this carcinogen has become the need of the hour. Cr(VI) removal through common physico-chemical techniques is highly expensive and inappropriate at low concentration. Microbial reduction of Cr(VI) to trivalent form is considered a favorable technique for Cr(VI) removal from wastewater, as it reduces the highly toxic form of Cr to less toxic form and therefore this article conveys essential fundamental information on removal of Cr(VI) by bacteria. For efficient bio-removal of Cr(VI), the main machinery of the process-”the microbes” and their conditions which decide the fate of this heavy metal, should be appropriate. Hence, this article covers vast information about the isolation of chromium resistant bacteria from various environment and their Cr(VI) resistance capability. Extensive report has been given on information pertaining to the factors such as cell density, pH, temperature, salt concentration, oxidation-reduction potential, electron donor, oxyanions, metabolic inhibitors and other heavy metals which influence or affect the efficient Cr(VI) removal, are discussed. Cr(VI) removal by immobilized bacterial cells and their advantages have also been summarized. In transferring this technology from laboratory to a large scale application, better understanding of all these aspects are necessary. Hence, this developing biotechnological method which encompasses fields from genetic engineering to reactor engineering demands for focused research in these directions, which may lead to implementation of this technology on a larger scale and drive it towards being the most opted technology.
    Critical Reviews in Environmental Science and Technology 01/2012; 43(9). DOI:10.1080/10643389.2011.627022 · 3.47 Impact Factor
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    • "Peptide identifications were filtered and sorted into proteins with DTASelect (Tabb et al., 2002) as described previously (VerBerkmoes et al., 2009). Contrast (Tabb et al., 2002) was used to display all proteins across runs, differentially expressed proteins were identified based on the following criteria (Chourey et al., 2006): at least under one condition, 440% sequence coverage, more than five unique peptides and X2-fold difference in spectral counts identified between DE195/DVH and DE195 isolate. Data identification as well as the actual MS/MS spectra from every peptide and accessory scores are available at "
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    ABSTRACT: Dehalococcoides ethenogenes strain 195 (DE195) was grown in a sustainable syntrophic association with Desulfovibrio vulgaris Hildenborough (DVH) as a co-culture, as well as with DVH and the hydrogenotrophic methanogen Methanobacterium congolense (MC) as a tri-culture using lactate as the sole energy and carbon source. In the co- and tri-cultures, maximum dechlorination rates of DE195 were enhanced by approximately three times (11.0±0.01 μmol per day for the co-culture and 10.1±0.3 μmol per day for the tri-culture) compared with DE195 grown alone (3.8±0.1 μmol per day). Cell yield of DE195 was enhanced in the co-culture (9.0±0.5 × 107 cells per μmol Cl− released, compared with 6.8±0.9 × 107 cells per μmol Cl− released for the pure culture), whereas no further enhancement was observed in the tri-culture (7.3±1.8 × 107 cells per μmol Cl− released). The transcriptome of DE195 grown in the co-culture was analyzed using a whole-genome microarray targeting DE195, which detected 102 significantly up- or down-regulated genes compared with DE195 grown in isolation, whereas no significant transcriptomic difference was observed between co- and tri-cultures. Proteomic analysis showed that 120 proteins were differentially expressed in the co-culture compared with DE195 grown in isolation. Physiological, transcriptomic and proteomic results indicate that the robust growth of DE195 in co- and tri-cultures is because of the advantages associated with the capabilities of DVH to ferment lactate to provide H2 and acetate for growth, along with potential benefits from proton translocation, cobalamin-salvaging and amino acid biosynthesis, whereas MC in the tri-culture provided no significant additional benefits beyond those of DVH.Keywords: Dehalococcoides; syntrophy; chlorinated ethenes; microarray; proteomics; bioremediation
    The ISME Journal 08/2011; 6(2):410-421. DOI:10.1038/ismej.2011.111 · 9.30 Impact Factor
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    • "Abiotic stresses, including heavy metals, induce changes in plant protein expression (Cuypers et al., 2005; Amme et al., 2006; Ndimba et al., 2005). Proteomic changes in response to Cr(VI) toxicity have been recently reported in bacteria, in the freshwater green alga Pseudokirchneriella subcapitata and in the leaves of Typha angustifolia (Chourey et al., 2006; Kılıç et al., 2010; Vannini et al., 2009; Bah et al., 2010). However, up to now there is no comparative proteomic report on protein pattern changes during Cr(III) and Cr(VI) stress in plants cells. "
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    ABSTRACT: The present study is aimed at identifying molecular changes elicited by Cr(III) and Cr(VI) on germinating kiwifruit pollen. To address this question, comparative proteomic and DNA laddering analyses were performed. While no genotoxic effect was detected, a number of proteins whose accumulation levels were altered by treatments were identified. In particular, the upregulation of some proteins involved in the scavenging response, cell redox homeostasis and lipid synthesis could be interpreted as an oxidative stress response induced by Cr treatment. The strong reduction of two proteins involved in mitochondrial oxidative phosphorylation and a decline in ATP levels were also observed. The decrease of pollen energy availability could be one of the causes of the severe inhibition of the pollen germination observed upon exposure to both Cr(III) and Cr(VI). Finally, proteomic and biochemical data indicate proteasome impairment: the consequential accumulation of misfolded/damaged proteins could be an important molecular mechanism of Cr(III) toxicity in pollen.
    Phytochemistry 06/2011; 72(14-15):1786-95. DOI:10.1016/j.phytochem.2011.06.001 · 2.55 Impact Factor
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