The cidA murein hydrolase regulator contributes to DNA release and biofilm development in Staphylococcus aureus

Abstract

The Staphylococcus aureus cidA and lrgA genes have been shown to affect cell lysis under a variety of conditions during planktonic growth. It is hypothesized that these genes encode holins and antiholins, respectively, and may serve as molecular control elements of bacterial cell lysis. To examine the biological role of cell death and lysis, we studied the impact of the cidA mutation on biofilm development. Interestingly, this mutation had a dramatic impact on biofilm morphology and adherence. The cidA mutant (KB1050) biofilm exhibited a rougher appearance compared with the parental strain (UAMS-1) and was less adherent. Propidium iodide staining revealed that KB1050 accumulated more dead cells within the biofilm population relative to UAMS-1, indicative of reduced cell lysis. In agreement with this finding, quantitative real-time PCR experiments demonstrated the presence of 5-fold less genomic DNA in the KB1050 biofilm relative to UAMS-1. Furthermore, treatment of the UAMS-1 biofilm with DNase I caused extensive cell detachment, whereas similar treatment of the KB1050 biofilm had only a modest effect. These results demonstrate that cidA-controlled cell lysis plays a significant role during biofilm development and that released genomic DNA is an important structural component of S. aureus biofilm.autolysis ͉ extracellular DNA ͉ programmed cell death ͉ holin

The antimicrobial and antibiofilm activities of copper(II) complexes

“…This has been found to be an important component of the extracellular matrix of biofilms, and for instance DNAse treatment significantly reduces the biomass of biofilms of S. aureus and other bacteria [28]. However, a number of other DNAbinding metallo-complexes that we tested have no or barely any activity on biofilms, including the aforementioned compounds 10 and 11, as well as other compounds such as major groove-binding complexes of iron [22] or ruthenium [23] (data not shown).…”

Fluconazole impacts the extracellular matrix of fluconazole-susceptible and -resistant Candida albicans and Candida glabrata biofilms

“…After that, biofilms were vortexed, centrifuged (5,500× g /10 min/4°C) and the supernatant containing the soluble part of the matrix was separated from the pellet, which contained the insoluble part of the matrix. The supernatant was divided for the quantification of WSPs (1 mL) [37], eDNA (0.650 mL) [38], and matrix protein in the soluble portion (0.150 mL) [39]. The pellet was washed twice and resuspended in sterile ultrapure water; then, it was separated for the quantification of insoluble biomass (0.8 mL), protein from the insoluble portion (0.05 mL) [39], and ASPs (0.95 mL) [37].…”

Phage-induced lysis enhances biofilm formation in Shewanella oneidensis MR-1

“…Other factors implicated in cell lysis are toxin/antitoxin system that have been characterized, for example, in Enterococcus faecalis (Thomas et al, 2008) and Staphylococcus sp. (Qin et al, 2007;Rice et al, 2007;Mann et al, 2009). However, a role for toxin/antitoxin systems in biofilm formation is not necessarily directly linked to cell lysis, as has been demonstrated for E. coli (Kim et al, , 2010.…”

“…In contrast, the significance of eDNA for cellular attachment and structural integrity has more recently been recognized for an increasing number of Gram-negative and Grampositive species (Whitchurch et al, 2002;Steinberger and Holden, 2005;Allesen-Holm et al, 2006;Moscoso et al, 2006;Jurcisek and Bakaletz, 2007;Qin et al, 2007;Izano et al, 2008;Thomas et al, 2008;Heijstra et al, 2009;Vilain et al, 2009;Harmsen et al, 2010;Lappann et al, 2010). Release of DNA in bacterial biofilms has mainly been attributed to the lysis of a cellular subpopulation, mediated by the activity of autolysis systems (Allesen-Holm et al, 2006;Rice et al, 2007;Thomas et al, 2008Thomas et al, , 2009Mann et al, 2009). The analysis of aggregates formed by S. oneidensis MR-1 in planktonic cultures indicated the presence of proteins, a-D-mannose or a-D-glucose containing exopolysaccharides, and substantial amounts of eDNA (McLean et al, 2008b).…”