This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Gilleland, H. E. Articles by Eagon, R. G. Search for Related Content PubMed PubMed Citation Articles by Gilleland, H. E., Jr. Articles by Eagon, R. G.

Ultrastructural and Chemical Alteration of the Cell Envelope of Pseudomonas aeruginosa, Associated with Resistance to Ethylenediaminetetraacetate Resulting from Growth in a Mg²⁺-Deficient Medium

Department of Microbiology, University of Georgia, Athens, Georgia 30602

ABSTRACT

Cells of Pseudomonas aeruginosa became resistant to the lytic effect of ethylenediametetraacetate (EDTA) when grown in a Mg²⁺-deficient medium. To correlate ultrastructural changes in the cell wall associated with the shift to EDTA-resistance, a freeze-etch study was performed. Upon fracturing, the outer cell wall membrane split down the hydrophobic center to reveal the outer (concave) and inner (convex) layers. The concave cell wall layer of EDTA-sensitive cells grown in Mg²⁺-sufficient medium contained spherical units resting on an underlying smooth support layer. Upon EDTA treatment, approximately one-half of these spherical units were extracted. Cells grown in Mg²⁺-deficient medium were resistant to EDTA. The concave cell wall layer of EDTA-resistant cells had increased numbers of highly compacted spherical units, giving this layer a disorganized appearance. The highly compacted appearance of this layer was unaltered by EDTA treatment. Thus, growth in Mg²⁺-deficient medium resulted in cells which were resistant to EDTA and which possessed an ultrastructurally altered outer layer of the outer cell wall membrane. Cell envelopes from EDTA-resistant cells were found to possess 18% less phosphorus, 16.4% more total carbohydrate, and 13.3% more 2-keto-3-deoxyoctonate than cell envelopes from EDTA-sensitive cells. There were also qualitative, but not quantitative, differences in the protein content of cell envelopes from EDTA-resistant and EDTA-sensitive cells.

¹ Present address: Department of Bacteriology and Immunology, University of Western Ontario, London 72, Ontario, Canada.

This article has been cited by other articles:

• Brown, A. R., Govan, J. R. W. (2007). Assessment of Fluorescent In Situ Hybridization and PCR-Based Methods for Rapid Identification of Burkholderia cepacia Complex Organisms Directly from Sputum Samples. J. Clin. Microbiol. 45: 1920-1926 [Abstract] [Full Text]  
• McPhee, J. B., Bains, M., Winsor, G., Lewenza, S., Kwasnicka, A., Brazas, M. D., Brinkman, F. S. L., Hancock, R. E. W. (2006). Contribution of the PhoP-PhoQ and PmrA-PmrB Two-Component Regulatory Systems to Mg2+-Induced Gene Regulation in Pseudomonas aeruginosa. J. Bacteriol. 188: 3995-4006 [Abstract] [Full Text]  
• Walker, J. R., Altman, E. (2005). Biotinylation Facilitates the Uptake of Large Peptides by Escherichia coli and Other Gram-Negative Bacteria. Appl. Environ. Microbiol. 71: 1850-1855 [Abstract] [Full Text]  
• Godoy, P., Ramos-Gonzalez, M. I., Ramos, J. L. (2001). Involvement of the TonB System in Tolerance to Solvents and Drugs in Pseudomonas putida DOT-T1E. J. Bacteriol. 183: 5285-5292 [Abstract] [Full Text]  
• Macfarlane, E. L. A., Kwasnicka, A., Hancock, R. E. W. (2000). Role of Pseudomonas aeruginosa PhoP-PhoQ in resistance to antimicrobial cationic peptides and aminoglycosides. Microbiology 146: 2543-2554 [Abstract] [Full Text]  
• McDonnell, G., Russell, A. D. (1999). Antiseptics and Disinfectants: Activity, Action, and Resistance. Clin. Microbiol. Rev. 12: 147-179 [Abstract] [Full Text]  
• Gotoh, N., Tsujimoto, H., Tsuda, M., Okamoto, K., Nomura, A., Wada, T., Nakahashi, M., Nishino, T. (1998). Characterization of the MexC-MexD-OprJ Multidrug Efflux System in Delta mexA-mexB-oprM Mutants of Pseudomonas aeruginosa. Antimicrob. Agents Chemother. 42: 1938-1943 [Abstract] [Full Text]