Extracellular DNA release acts as an antifungal resistance mechanism in mature aspergillus fumigatus biofilms

Rajendran, R., Williams, C., Lappin, D.F., Millington, O., Martins, M. and Ramage, G. (2013) Extracellular DNA release acts as an antifungal resistance mechanism in mature aspergillus fumigatus biofilms. Eukaryotic Cell, 12(3), pp. 420-429. (doi:10.1128/EC.00287-12)

Rajendran, R., Williams, C., Lappin, D.F., Millington, O., Martins, M. and Ramage, G. (2013) Extracellular DNA release acts as an antifungal resistance mechanism in mature aspergillus fumigatus biofilms. Eukaryotic Cell, 12(3), pp. 420-429. (doi:10.1128/EC.00287-12)

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Abstract

Aspergillus fumigatus has been shown to form biofilms that are associated with adaptive antifungal resistance mechanisms. These include multidrug efflux pumps, heat shock proteins, and extracellular matrix (ECM). ECM is a key structural and protective component of microbial biofilms and in bacteria has been shown to contain extracellular DNA (eDNA). We therefore hypothesized that A. fumigatus biofilms also possess eDNA as part of the ECM, conferring a functional role. Fluorescence microscopy and quantitative PCR analyses demonstrated the presence of eDNA, which was released phase dependently (8 < 12 < 24 < 48 h). Random amplification of polymorphic DNA (RAPD) PCR showed that eDNA was identical to genomic DNA. Biofilm architectural integrity was destabilized by DNase treatment. Biochemical and transcriptional analyses showed that chitinase activity and mRNA levels of chitinase, a marker of autolysis, were significantly upregulated as the biofilm matured and that inhibition of chitinases affected biofilm growth and stability, indicating mechanistically that autolysis was possibly involved. Finally, using checkerboard assays, it was shown that combinational treatment of biofilms with DNase plus amphotericin B and caspofungin significantly improved antifungal susceptibility. Collectively, these data show that eDNA is an important structural component of A. fumigatus ECM that is released through autolysis, which is important for protection from environmental stresses, including antifungal therapy.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Lappin, Dr David and Ramage, Professor Gordon and Rajendran, Dr Ranjith and Williams, Dr Craig
Authors: Rajendran, R., Williams, C., Lappin, D.F., Millington, O., Martins, M., and Ramage, G.
College/School:College of Medical Veterinary and Life Sciences > School of Medicine, Dentistry & Nursing
College of Medical Veterinary and Life Sciences > School of Medicine, Dentistry & Nursing > Dental School
Journal Name:Eukaryotic Cell
ISSN:1535-9778
ISSN (Online):1535-9786
Published Online:11 January 2013

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