Changes in the Protein Profiles of Staphylococcus epidermidis Planktonic Cultures and Biofilms under Anoxic Conditions in the Presence of the CNP Hormone

Although natriuretic peptides (NP) may affect the biofilms of human commensal microorganisms, including members of the genus Staphylococcus, no literature data on molecular changes caused by these hormones at the posttranslational level are available. The present work is the first report on noticeable changes in protein profiles of Staphylococcus epidermidis cells and biofilms caused by the C-type natriuretic peptide (CNP). The presence of the hormone caused a more pronounced difference in protein profiles between planktonic cells and biofilms compared to the control pairs of samples. The main processes affected were the TCA cycle, protein transport, purine synthesis (decreased content of the relevant proteins in biofilms) and nitrate metabolism (increased content of nitrogenases and other proteins in biofilms). Decreased content of lysostaphin in biofilms compared to planktonic cultures caused by exposure to CNP should be mentioned specifically. This may be one of the potential mechanisms of the recently shown decreased competitiveness of S. epidermidis in communities with other microorganisms, which is induced by the presence of CNP in the medium. Moreover, our results support the hypothesis that, as in the case of other human hormones, the effect of CNP on S. epidermidis is multitargeted. One of the likely mechanisms of the action of the hormone may be the disruption of transition from planktonic culture to the biofilm, which can be assumed without suppressing cell growth, which needs further verification.