Abstract
Hexavalent chromium [Cr(VI)] is a soluble carcinogen that has caused widespread contamination of soil and water in many industrial nations. Bacteria have the potential to aid remediation as certain strains can catalyze the reduction of Cr(VI) to insoluble and less toxic Cr(III). Here, we examine Cr(VI) reducing Microbacterium spp. (Cr-K1W, Cr-K20, Cr-K29, and Cr-K32) isolated from contaminated sediment (Seymore, Indiana) and show varying chromate responses despite the isolates’ phylogenetic similarity (i.e., identical 16S rRNA gene sequences). Detailed analysis identified differences based on genomic metabolic potential, growth and general metabolic capabilities, and capacity to resist and reduce Cr(VI). Taken together, the discrepancies between the isolates demonstrate the complexity inter-strain variation can have on microbial physiology and related biogeochemical processes.
Highlights
Chromium (Cr) has become a major environmental pollutant due to its extensive use in industrial and mining industries (Barak et al, 2006; Brose & James, 2010; Cheng, Holman & Lin, 2012)
Chromium is of particular concern because of its solubility in water and potential risk to drinking water; as well as the potential to inhibit the natural microbial communities engaged in the bioremediation of other pollutants (Baath, 1989; Gough et al, 2008; Gough & Stahl, 2011; Kourtev, Nakatsu & Konopka, 2009; Nakatsu et al, 2005; Said & Lewis, 1991)
Bacterial isolation and characterization of chromate resistance and reduction Four bacterial strains isolated from chromium contaminated soil samples were studied for their ability to resist and reduce Cr(VI)
Summary
Chromium (Cr) has become a major environmental pollutant due to its extensive use in industrial and mining industries (Barak et al, 2006; Brose & James, 2010; Cheng, Holman & Lin, 2012). Cr(VI) is highly toxic, soluble, and can be transported across cell membranes of both eukaryotic and prokaryotic organisms via sulfate and other active transporters (Ackerley et al, 2004b; Cheng, Holman & Lin, 2012). Cr(III) is sparingly soluble, thermodynamically stable, and found in oxide, hydroxide, and sulfate minerals, or complexed by organic matter (Barak et al, 2006; Brose & James, 2010; Oze, Bird & Fendorf, 2007; Oze et al, 2004; Viti et al, 2013). Many microorganisms have been found to possess various mechanisms to reduce Cr(VI), which has potential impacts on bioremediation strategies (Suzuki et al, 1992)
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