摘要：SummaryPseudomonas aeruginosabiofilms represent a major threat to health care. Rugose small colony variants (RSCV) ofP.aeruginosa, isolated from chronic infections, display hyperbiofilm phenotype. RSCV biofilms are highly resistant to antibiotics and host defenses. This work shows that RSCV biofilm aggregates consist of two distinct bacterial subpopulations that are uniquely organized displaying contrasting physiological characteristics. Compared with that of PAO1, the extracellular polymeric substance of RSCV PAO1ΔwspFbiofilms presented unique ultrastructural characteristics. Unlike PAO1, PAO1ΔwspFreleased fragmented extracellular DNA (eDNA) from live cells. Fragmented eDNA, thus released, was responsible for resistance of PAO1ΔwspFbiofilm to disruption by DNaseI. When added to PAO1, such fragmented eDNA enhanced biofilm formation. Disruption of PAO1ΔwspFbiofilm was achieved by aurine tricarboxylic acid, an inhibitor of DNA-protein interaction. This work provides critical novel insights into the contrasting structural and functional characteristics of a hyperbiofilm-forming clinical bacterial variant relative to its own wild-type strain.Graphical AbstractDisplay OmittedHighlights•Hyperbiofilm clinical isolate PAO1ΔwspFcontain unique cell state and organization•Bacterial cells in PAO1ΔwspFbiofilm are morphologically and physiologically unique•PAO1ΔwspF, unlike PAO1 that undergo explosive lysis, release eDNA from live cells•Aurine tricarboxylic acid, not DNAseI as for PAO1, disrupts PAO1ΔwspFbiofilmMicrobiology; Microbiofilms
