Proteomic Analysis Reveals a Biofilm-Like Behavior of Planktonic Aggregates of Staphylococcus epidermidis Grown Under Environmental Pressure/Stress

Abstract

Prosthetic joint replacement failure has a huge impact on quality of life and hospitalization costs. A leading cause of prosthetic joint infection is bacteria-forming biofilm on the surface of orthopedic devices. Staphylococcus epidermidis is an emergent, lowvirulence pathogen implicated in chronic infections, barely indistinguishable from aseptic loosening when embedded in a mature matrix. The literature on the behavior of quiescent S. epidermidis in mature biofilms is scarce. To fill this gap, we performed comparative analysis of the whole proteomic profiles of two methicillin-resistant S. epidermidis strains growing in planktonic and in sessile form to investigate the molecular mechanisms underlying biofilm stability. After 72-h culture of biofilmforming S. epidermidis, overexpression of proteins involved in the synthesis of nucleoside triphosphate and polysaccharides was observed, whereas planktonic bacteria expressed proteins linked to stress and anaerobic growth. Cytological analysis was performed to determine why planktonic bacteria unexpectedly expressed proteins typical of sessile culture. Images evidenced that prolonged culture under vigorous agitation can create a stressful growing environment that triggers microorganism aggregation in a biofilm-like matrix as a mechanism to survive harsh conditions. The choice of a unique late time point provided an important clue for future investigations into the biofilm-like behavior of planktonic cells. Our preliminary results may inform comparative proteomic strategies in the study of mature bacterial biofilm. Finally, there is an increasing number of studies on the aggregation of free-floating bacteria embedded in an extracellular matrix, prompting the need to gain further insight into this mode of bacterial growth.

Phenotypic Modulation of Biofilm Formation in a Staphylococcus epidermidis Orthopedic Clinical Isolate Grown Under Different Mechanical Stimuli: Contribution From a Combined Proteomic Study

“…A previous study on the proteome of S. epidermidis GOI1153754-03-14 demonstrated the ability of this clinical isolate to form aggregates after 72 h of culture (Bottagisio et al, 2019). This peculiar behavior may be a survival mechanism to cope with harsh conditions after prolonged culture in a media without renewed nutrients (Bottagisio et al, 2019). In the present study, planktonic S. epidermidis showed the ability to aggregate after 24 h and synthesize cell wall molecules which contribute to this phenotype.…”

“…Although planktonic bacteria were grown under vigorous agitation to prevent their adhesion and the subsequent biofilm formation, LFQ analysis revealed the presence of proteins linked to biofilm-like behavior. A previous study on the proteome of S. epidermidis GOI1153754-03-14 demonstrated the ability of this clinical isolate to form aggregates after 72 h of culture (Bottagisio et al, 2019). This peculiar behavior may be a survival mechanism to cope with harsh conditions after prolonged culture in a media without renewed nutrients (Bottagisio et al, 2019).…”

“…S. epidermidis ATCC 35984 is known to have a faster growth rate compared to the clinical isolate strain (Bottagisio et al, 2019); this is characterized by a different proteomic profile even after 24 h of either sessile or planktonic culture (data not shown). Since the aforementioned culture conditions did not make it possible to determine which proteins are crucial for the initial steps of biofilm formation process, attention was then focused only on the restricted number of proteins differentially expressed by S. epidermidis GOI1153754-03-14 sessile and planktonic forms at the beginning of the biofilm formation process after 24 h of culture.…”

A universal stress protein in Mycobacterium smegmatis sequesters the cAMP-regulated lysine acyltransferase and is essential for biofilm formation

“…For example, deletion of the uspA gene in Porphyromonas gingivitis resulted in poor biofilm formation, and levels of UspA were increased during biofilm formation (57). A uspA gene in Staphylococcus epidermidis is upregulated in planktonic aggregates that show biofilm-like behaviour (58). Finally, deletion of a usp gene in Micrococcus luteus regulated the expression of a number of genes including those involved in central carbon metabolism (59).…”

Antimicrobial Effects of Conditioned Medium From Amniotic Progenitor Cells in vitro and in vivo: Toward Tissue Regenerative Therapies for Bovine Mastitis

“…Briefly, reduction (DTT 8 mM in urea buffer −8 M urea and 100 mM Tris), alkylation (IAA 50 mM in urea buffer −8 M urea and 100 mM Tris), and digestion by trypsin at a final concentration of 0.01 µg/µl (Promega Italia srl, Milan, Italy) were performed on filter tubes (Nanosep centrifugal device with Omega membrane-30 K MWCO, Sigma-Aldrich). LC-MS analysis was performed as previously described (39). First, 500 fmol/µl of digestion of enolase from Saccharomyces cerevisiae (P00924) was added to each sample as an internal standard, tryptic peptides were separated, and then 0.25 µg of each digested sample was loaded onto a Symmetry C18 5 µm, 180 µm × 20 mm precolumn (Waters Corp., Milford, MA, United States) and subsequently separated by a 90-min reversed-phase gradient at 300 nl/min (linear gradient, 2-85% CH3CN over 90 min) using a HSS T3 C18 1.8 µm, 75 µm × 150 mm nanoscale LC column (Waters Corp.) maintained at 40 • C. The separated peptides were analyzed on a high-definition Synapt G2-Si Mass spectrometer directly coupled to the chromatographic system.…”