Science and Mathematics Faculty Publications

The Effect of a Cationic Porphyrin on Pseudomonas aeruginosa Biofilms

Document Type

Article

Publication Date

11-2010

Journal Title

Current Microbiology

ISSN

0343-8651

Volume

61

Issue

5

First Page

411

Last Page

416

DOI

10.1007/s00284-010-9629-y

Abstract

Current studies have indicated the utility of photodynamic therapy using porphyrins in the treatment of bacterial infections. Photoactivation of porphyrins results in the production of singlet oxygen (1O2) that damages biomolecules associated with cells and biofilms, e.g., proteins, polysaccharides, and DNA. The effect of a cationic porphryin on P. aeruginosa PAO1 biofilms was assessed by exposing static biofilms to 5,10,15,20-tetrakis(1-methyl-pyridino)-21H,23H-porphine, tetra-p-tosylate salt (TMP) followed by irradiation. Biofilms were visualized using confocal laser scanning microscopy (CLSM) and cell viability determined using the LIVE/DEAD BacLight viability assay and standard plate counts. At a concentration of 100 μM TMP, there was substantial killing of P. aeruginosa PAO1 wild-type and pqsA mutant biofilms with little disruption of the biofilm matrix or structure. Exposure to 225 μM TMP resulted in almost complete killing as well as the detachment of wild-type PAO1 biofilms. In contrast, pqsA mutant biofilms that contain less extracellular DNA remained intact. Standard plate counts of cells recovered from attached biofilms revealed a 4.1-log10 and a 3.9-log10 reduction in viable cells of wild-type PAO1 and pqsA mutant strains, respectively. Our results suggest that the action of photoactivated TMP on P. aeruginosa biofilms is two-fold: direct killing of individual cells within biofilms and detachment of the biofilm from the substratum. There was no evidence of porphyrin toxicity in the absence of light; however, biofilms pretreated with TMP without photoactivation were substantially more sensitive to tobramycin than untreated biofilms.

Keywords

Tobramycin, Minimal Salt Medium, Standard Plate Count, Cationic Porphyrin, BacLight Bacterial Viability

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

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