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Impact of growth environment and physiological state on metal immobilization by Pseudomonas aeruginosa PAO1

Hunter, Ryan C. and Phoenix, Vernon R. and Saxena, Anuradha and Beveridge, Terry J. (2010) Impact of growth environment and physiological state on metal immobilization by Pseudomonas aeruginosa PAO1. Canadian Journal of Microbiology, 56 (7). pp. 527-538. ISSN 0008-4166. http://resolver.caltech.edu/CaltechAUTHORS:20100909-111540019

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Abstract

Environmental growth conditions and cell physiology have the potential to influence bacterial surface–metal interactions in both planktonic and biofilm systems. Here, Pseudomonas aeruginosa was studied to determine the influence of these factors (pH, redox potential, and active respiration) on surface electrostatics and metal immobilization. Acid–base titrations revealed a decrease in ionizable ligands at pK_a5 (putative carboxyls) in cells grown below pH 6.2 and in cells grown anaerobically relative to cells grown under oxic and circumneutral pH conditions. This observation correlates with Western immunoblotting assays that revealed a reduction in carboxylated B-band lipopolysaccharide in these cells. Furthermore, spectrophotometric analysis revealed a decrease in zinc, copper, and iron immobilization in these cells, suggesting that lipopolysaccharide modification in response to environmental stimuli influences metal binding. The effect of active versus inactive metabolism on metal adsorption was also examined using respiration inhibitors carbonyl cyanide m-chlorophenylhydrazone and sodium azide. Cells treated with these compounds bound more zinc, copper, and iron than untreated controls, suggesting proton extrusion through respiration competes with metal cations for reactive groups on the cell surface. Accumulation of gold did not show the same trend, and transmission electron microscopy studies confirmed it was not a surface-mediated process. These results suggest that variations in growth environment and cell physiology influence metal accumulation by bacterial cell surfaces and may help to explain discontinuous accumulation of metal observed throughout microbial communities.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1139/W10-038 DOIUNSPECIFIED
Additional Information:© 2010 Published by NRC Research Press. Received 30 November 2009. Revision received 23 March 2010. Accepted 23 April 2010. Published on the NRC Research Press Web site at cjm.nrc.ca on 24 June 2010. R.C.H. was funded through a Natural Science and Engineering Research Council of Canada (NSERC) graduate fellowship. Experimentation was funded through NSERC– Discovery, US Department of Energy, and Advanced Food and Materials Network (AFMnet) – Network Centres of Excellence grants to T.J.B. The electron microscopy was performed in the NSERC Guelph Regional Integrated Imaging Facility (GRIIF), which is partially funded through an NSERC Major Facilities Access grant to T.J.B.
Funders:
Funding AgencyGrant Number
Natural Science and Engineering Research Council of Canada (NSERC) UNSPECIFIED
Department of Energy (DOE)UNSPECIFIED
Advanced Food and Materials Network (AFMnet) - Network Centres of Excellence UNSPECIFIED
Subject Keywords:biofilms, microenvironments, biomineralization, acid–base titrations
Record Number:CaltechAUTHORS:20100909-111540019
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20100909-111540019
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:19847
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:15 Sep 2010 21:51
Last Modified:25 Oct 2017 19:16

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