title: Bioremediation of hexavalent chromium (VI) by a soil-borne bacterium, Enterobacter cloacae B2-DHA.
abstract: Chromium and chromium containing compounds are discharged into the nature as waste from anthropogenic activities, such as industries, agriculture, forest farming, mining and metallurgy. Continued disposal of these compounds to the environment leads to development of various lethal diseases in both humans and animals. In this paper, we report a soil borne bacterium, B2-DHA that can be used as a vehicle to effectively remove chromium from the contaminated sources. B2-DHA is resistant to chromium with a MIC value of 1000 µg mL(-1) potassium chromate. The bacterium has been identified as a Gram negative, Enterobacter cloacae based on biochemical characteristics and 16S rRNA gene analysis. TOF-SIMS and ICP-MS analyses confirmed intracellular accumulation of chromium and thus its removal from the contaminated liquid medium. Chromium accumulation in cells was 320 µg/g of cells dry biomass after 120-h exposure, and thus it reduced the chromium concentration in the liquid medium by as much as 81%. Environmental scanning electron micrograph revealed the effect of metals on cellular morphology of the isolates. Altogether, our results indicate that B2-DHA has the potential to reduce chromium significantly to safe levels from the contaminated environments and suggest the potential use of this bacterium in reducing human exposure to chromium, hence avoiding poisoning.
authors.affiliation: a Systems Biology Research Center, School of Bioscience, University of Skövde , Skövde , Sweden.
authors.forename: Aminur
authors.initials: A
authors.lastname: Rahman
authors.forename: Noor
authors.initials: N
authors.lastname: Nahar
authors.forename: Neelu N
authors.initials: NN
authors.lastname: Nawani
authors.forename: Jana
authors.initials: J
authors.lastname: Jass
authors.forename: Khaled
authors.initials: K
authors.lastname: Hossain
authors.forename: Zahangir Alam
authors.initials: ZA
authors.lastname: Saud
authors.forename: Ananda K
authors.initials: AK
authors.lastname: Saha
authors.forename: Sibdas
authors.initials: S
authors.lastname: Ghosh
authors.forename: Björn
authors.initials: B
authors.lastname: Olsson
authors.forename: Abul
authors.initials: A
authors.lastname: Mandal
mesh_terms: D001459:Bangladesh; D001673:Biodegradation, Environmental; D002857:Chromium / Q000378:metabolism*; D016972:Enterobacter cloacae / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D007220:Industrial Waste / Q000032:analysis*; D010802:Phylogeny; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000302:isolation & purification*; D013633:Tanning
chemical_list: D007220:Industrial Waste; D012989:Soil Pollutants; D002857:Chromium; C074702:chromium hexavalent ion
keywords: Bioremediation; Enterobacter cloacae; chromium; human health; soil borne bacterium; tannery effluents