Effects of colistin on surface ultrastructure and nanomechanics of pseudomonas aeruginosa cells

Ninell P. Mortensen, Jason D. Fowlkes, Claretta J. Sullivan, David P. Allison, Niels B. Larsen, Søren Molin, Mitchel J. Doktycz

Research output: Contribution to journalArticlepeer-review

87 Scopus citations

Abstract

Chronic lung infections in cystic fibrosis patients are primarily caused by Pseudomonas aeruginosa. Though difficult to counteract effectively, Colistin, an antimicrobial peptide, is proving useful. However, the exact mechanism of action, of Colistin is not fully understood. In this study, atomic force microscopy (AFM) was used to evaluate, in a liquid environment, the changes in P. aeruginosa morphology and nanomechanical properties due to exposure to Colistin. The results of this work revealed that after 1 h of Colistin exposure the ratio of individual bacteria to those found, to be arrested in the process of division changed from 1.9 to 0.4 and the length of the cells decreased significantly. Morphologically, it was observed that the bacterial surface changed from a smooth to a wrinkled phenotype after 3 h exposure to Colistin. Nanomechanically, in untreated bacteria, the cantilever indented the bacterial surface significantly more than it did after 1 h of Colistin treatment (P-value = 0.015). Concurrently, after 2 h of exposure to Colistin, a significant increase in the bacterial spring constant was also observed. These results indicate that the antimicrobial peptide Colistin prevents bacterial proliferation by repressing cell division. We also found that treatment with Colistin caused an increase in the rigidity of the bacterial cell wall while morphologically the cell surface changed from, smooth to wrinkled, perhaps due to loss of lipopolysaccharides (LPS) or surface proteins.

Original languageEnglish
Pages (from-to)3728-3733
Number of pages6
JournalLangmuir
Volume25
Issue number6
DOIs
StatePublished - Mar 17 2009

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