Role of the SaeRS two-component regulatory system in Staphylococcus epidermidisautolysis and biofilm formation

Abstract

BackgroundStaphylococcus epidermidis (SE) has emerged as one of the most important causes of nosocomial infections. The SaeRS two-component signal transduction system (TCS) influences virulence and biofilm formation in Staphylococcus aureus. The deletion of saeR in S. epidermidis results in impaired anaerobic growth and decreased nitrate utilization. However, the regulatory function of SaeRS on biofilm formation and autolysis in S. epidermidis remains unclear.ResultsThe saeRS genes of SE1457 were deleted by homologous recombination. The saeRS deletion mutant, SE1457ΔsaeRS, exhibited increased biofilm formation that was disturbed more severely (a 4-fold reduction) by DNase I treatment compared to SE1457 and the complementation strain SE1457saec. Compared to SE1457 and SE1457saec, SE1457ΔsaeRS showed increased Triton X-100-induced autolysis (approximately 3-fold) and decreased cell viability in planktonic/biofilm states; further, SE1457ΔsaeRS also released more extracellular DNA (eDNA) in the biofilms. Correlated with the increased autolysis phenotype, the transcription of autolysis-related genes, such as atlE and aae, was increased in SE1457ΔsaeRS. Whereas the expression of accumulation-associated protein was up-regulated by 1.8-fold in 1457ΔsaeRS, the expression of an N-acetylglucosaminyl transferase enzyme (encoded by icaA) critical for polysaccharide intercellular adhesin (PIA) synthesis was not affected by the deletion of saeRS.ConclusionsDeletion of saeRS in S. epidermidis resulted in an increase in biofilm-forming ability, which was associated with increased eDNA release and up-regulated Aap expression. The increased eDNA release from SE1457ΔsaeRS was associated with increased bacterial autolysis and decreased bacterial cell viability in the planktonic/biofilm states.

Differences between Two Clinical Staphylococcus capitis Subspecies as Revealed by Biofilm, Antibiotic Resistance, and Pulsed-Field Gel Electrophoresis Profiling

“…In addition, a regulatory gene called icaR is located upstream and is transcribed in the opposite direction (4). Other surface molecules involved in the accumulation phase of biofilm formation include accumulation-associated protein (Aap) (5), extracellular matrixbinding protein (Embp) (6), and extracellular DNA (7). Aap is a 220-kDa LPXTG protein (8).…”

The synergy of berberine chloride and totarol against Staphylococcus aureus grown in planktonic and biofilm cultures

“…Here, a dot-blot assay was used to detect the production of PIA in the biofilm extracellular matrix. PIA was detected as described previously (Lou et al, 2011). Briefly, S. aureus strains were grown in 6-well plates under static conditions at 37 uC for 24 h. Then, the cells were scraped off and resuspended in 0.5 M EDTA (pH 8.0).…”

Oxidation-sensing Regulator AbfR Regulates Oxidative Stress Responses, Bacterial Aggregation, and Biofilm Formation in Staphylococcus epidermidis

“…Role of AbfR in Biofilm Formation-To examine whether AbfR modulates biofilm formation in S. epidermidis, we performed a semiquantitative adherence assay as previously described (39,40,42). As shown in Fig.…”

“…Biofilm Formation Assay-As previously described, the microtiter plate test was used to quantify the biofilm (39,40) with slight modifications. Briefly, overnight culture of S. epidermidis strains in BM medium was diluted 1:100 in fresh BM and grown with aeration at 37°C for 12 h. The culture was further diluted in fresh TSB to A 600 of 0.01 and then inoculated into a sterile 96-well polystyrene microtiter plates (200 l/well).…”