Extracellular DNA release confers heterogeneity in Candida albicans biofilm formation

Rajendran, R., Sherry, L. , Lappin, D. F., Nile, C. J. , Smith, K., Williams, C., Munro, C. A. and Ramage, G. (2014) Extracellular DNA release confers heterogeneity in Candida albicans biofilm formation. BMC Microbiology, 14, 303. (doi: 10.1186/s12866-014-0303-6) (PMID:25476750) (PMCID:PMC4262977)

Abstract

<b>Background</b> Biofilm formation by <i>Candida albicans</i> has shown to be highly variable and is directly associated with pathogenicity and poor clinical outcomes in patients at risk. The aim of this study was to test the hypotheses that the extracellular DNA release by <i>C. albicans</i> is strain dependent and is associated with biofilm heterogeneity.<p></p> <b>Results</b> Initially, biofilm formed by <i>C. albicans</i> high biofilm formers (HBF) or low biofilm formers (LBF) were treated with DNase to find whether eDNA play a role in their biofilm formation. Digestion of biofilm eDNA significantly reduced the HBF biofilm biomass by five fold compared to untreated controls. In addition, quantification of eDNA over the period of biofilm formation by SYBR green assay demonstrate a significantly higher level of 2 to 6 fold in HBF compared to LBF. Biochemical and transcriptional analyses showed that chitinase activity and mRNA levels of chitinase genes, a marker of autolysis, were upregulated in 24 h biofilm formation by HBF compared to LBF, indicating autolysis pathway possibly involved in causing variation. The biofilm biomass and eDNA release by single <i>(∆cht2, ∆cht3)</i> and double knockout <i>(∆cht2/∆cht3)</i> chitinase mutants were significantly less compared to their parental strain CA14, confirming the role of chitinases in eDNA release and biofilm formation. Correlation analysis found a positive correlation between chitinases and <i>HWP</i>1, suggesting eDNA may release during the hyphal growth. Finally, we showed a combinational treatment of biofilms with DNase or chitinase inhibitor (acetazolamide) plus amphotericin B significantly improved antifungal susceptibility by 2 to 8 fold.<p></p> <b>Conclusions</b> Collectively, these data show that eDNA release by <i>C. albicans</i> clinical isolates is variable and is associated with differential biofilm formation. Digestion of biofilm eDNA by DNase may provide a novel therapeutic strategies to destabilise biofilm growth and improves antifungal sensitivity.<p></p>

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Smith, Dr Karen and Lappin, Dr David and Ramage, Professor Gordon and Rajendran, Dr Ranjith and Williams, Dr Craig and Nile, Dr Christopher and Sherry, Dr Leighann
• Authors: Rajendran, R., Sherry, L., Lappin, D. F., Nile, C. J., Smith, K., Williams, C., Munro, C. A., 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: BMC Microbiology
• Publisher: BioMed Central
• ISSN: 1471-2180
• ISSN (Online): 1471-2180
• Copyright Holders: Copyright © 2014 The Authors
• First Published: First published in BMC Microbiology 14:303
• Publisher Policy: Reproduced under a Creative Commons License