Phosphatase mediated bioprecipitation of lead as pyromorphite by Achromobacter xylosoxidans. (1st July 2018)

• Record Type: Journal Article
• Authors: Sharma, Jaya; Shamim, Kashif; Dubey, Santosh Kumar
• Is Part Of: Journal of environmental management. Volume 217(2018)
• Page Start: 754
• Page End: 761
• Publication Date: 2018-07-01
• Subjects: Lead precipitation -- SEM-EDX -- XRD -- Pyromorphite -- Phosphatase -- LC-MS/MS; Environmental policy -- Periodicals; Environmental management -- Periodicals; Environment -- Periodicals; Ecology -- Periodicals; 363.705
• DOI: 10.1016/j.jenvman.2018.04.027
• Languages: English
• ISSNs: 0301-4797

Abstract

Abstract: Achromobacter xylosoxidans strain SJ11, tolerating up to 4.0 mM lead nitrate, in a defined minimal medium was isolated from the waste of a battery manufacturing industry, Goa, India. Interestingly, it formed white precipitate on exposure to lead nitrate which was also evident from scanning electron micrograph (SEM). Energy dispersive X-ray spectroscopic analysis revealed the presence of lead (48.5% by weight) along with phosphorus and chlorine in the precipitate. Transmission electron microscopy (TEM) of bacterial cells clearly refuted the possibility of intracellular lead uptake confirming extracellular precipitation as a predominant mechanism of lead resistance in this bacterium. The extracellular precipitate was further identified as pyromorphite [Pb5 (PO4 )3 Cl] by X-ray diffraction analysis. This was also corroborated by fourier transformed infrared spectroscopy (FTIR) indicating a significant involvement of phosphate groups. Atomic absorption spectroscopic analysis clearly demonstrated that 465.8 mg g −1 lead was precipitated by the bacterial cells. There was remarkable increase of 160% in phosphatase activity suggesting it's important role in lead precipitation. This was further substantiated by significant up-regulation of phosphatase, CheZ using LC-MS/MS. Therefore phosphatase mediated extracellular precipitation of lead as pyromorphite by A. xylosoxidans strain SJ11 clearly demonstrated it's potential in bioremediation of lead contaminated environmental sites. Graphical abstract: Image 1 Highlights: Achromobacter xylosoxidans strain SJ11 precipitates lead extracellularly. Lead constituted 48.5% of the precipitate. Lead precipitate was identified as pyromorphite [Pb5 (PO4)3Cl]. Phosphatase, CheZ showed 1.73 fold up-regulation in presence of 0.2 mM lead.