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

Qiang Lou12, Tao Zhu1, Jian Hu1, Haijing Ben1, Jinsong Yang3, Fangyou Yu4, Jingran Liu1, Yang Wu1*, Adrien Fischer5, Patrice Francois5, Jacques Schrenzel5 and Di Qu1*

Author Affiliations

1 Key laboratory of Medical Molecular Virology of Ministry of Education and Ministry of Public Health, Institute of Medical Microbiology and Institutes of Biomedical Sciences, Shanghai Medical College of Fudan University, 138 Yixueyuan Road, Shanghai, 200032, PR China

2 Laboratory of Cellular and Molecular Immunology, Henan University, Jinming Road, Kaifeng, 475004, PR China

3 Department of Orthopedics, The First Affiliated Hospital of Guangxi Medical University, 6 Shuangyong Road, Nanning, 530021, PR China

4 Department of Laboratory Medicine, the First Affiliated Hospital of Wenzhou Medical College, 2 Fuxue Road, Wenzhou, 325000, PR China

5 Genomic Research Laboratory, Service of Infectious Diseases, University of Geneva Hospitals, Rue Gabrielle-Perret-Gentil 4, Geneva, CH-1211, Switzerland

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BMC Microbiology 2011, 11:146  doi:10.1186/1471-2180-11-146

Published: 24 June 2011

Additional files

Additional file 1:

Fig. S1. Growth curves of SE1457ΔsaeRS and the parental strain in aerobic (A) or anaerobic (B) growth conditions. Overnight cultures were diluted 1:200 and incubated at 37°C with shaking at 220 rpm. The OD600 of the cultures was measured at 60 min intervals for 12 h. For anaerobic growth conditions, bacteria were cultured in the Eppendorf tubes that were filled up with the TSB medium and sealed with wax. WT, SE1457; SAE, SE1457ΔsaeRS.

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Additional file 2:

Fig. S2. PIA detection in S. epidermidis biofilms. S. epidermidis strains were grown in 6-well plates under static conditions at 37°C for 24 h. Next, the cells were removed by scraping and collected by centrifugation before being resuspended in 0.5 M EDTA (pH 8.0). After proteinase K treatment (20 mg/mL) for 3 h at 37°C, serial dilutions of the PIA extracts were spotted onto PVDF membranes. Spots corresponding to PIA were quantified using the Quantity-one software. WT, SE1457; SAE, SE1457ΔsaeRS; SAEC, SE1457saec; 35984, S. epidermidis ATCC35984.

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Additional file 3:

Fig. S3. SE1457ΔsaeRS and wild-type strain 2-DE profiles. SE1457ΔsaeRS and SE1457 were grown in TSB medium at 37°C until the post-exponential growth phase; the bacteria were then separated by centrifugation. Bacteria cell pellets were dissolved in lysis buffer and sonicated on ice. The 2-DE gels were performed using 24 cm immobilized dry strips (IPG, nonlinear, pH 4-7, GE Healthcare) and analyzed by ImageMaster 2D platinum 6.0 software (Amersham Biosciences). Protein spots were identified using a 4700 MALDI-TOF/TOF Proteomics Analyzer (Applied Biosystems, California, USA).

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Additional file 4:

Fig. S4. Detection of Aap expression. Aap in lysostaphin-treated bacterial cells of SE1457ΔsaeRS, SE1457, and SE1457saec was detected by Western blot using an anti-Aap monoclonal antibody (made in our laboratory). Proteins were separated on 7% SDS-PAGE gels and then transferred to polyvinylidene fluoride (PVDF) membranes by electroblotting. Bands corresponding to Aap were quantified using the Quantity-one software. WT, SE1457; SAE, SE1457ΔsaeRS; SAEC, SE1457sae.

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