Extracellular DNA Chelates Cations and Induces Antibiotic Resistance in Pseudomonas aeruginosa Biofilms (original) (raw)
Figure 2
Extracellular DNA induces membrane perturbation, cell lysis, DNA release and death.
(A) Membrane integrity was monitored by visualizing DNA, EDTA or buffer treated P. aeruginosa producing mCherry fluorescent lipoproteins in either the IM or OM. The release of OMVs (white arrow) and genomic DNA strands (grey arrow) into the extracellular milieu following cell lysis in response to DNA or EDTA treatment was demonstrated by (B) PI staining and (C) semi-quantitative PCR which detects P. aeruginosa genomic DNA but not salmon sperm DNA. Cells were treated with 2% (w/v) salmon sperm DNA, 2 mM EDTA, or buffer alone (negative control), pelleted and 1 µl of supernatent used as a template for semi-quantitative PCR. PCR controls included 2% (w/v) salmon sperm DNA (primer specificity) and a negative and positive PCR control. The scale bar equals 2.5 microns.