Identification and characterisation of capidermicin, a novel bacteriocin produced by Staphylococcus capitis

Abstract

One hundred human-derived coagulase negative staphylococci (CoNS) were screened for antimicrobial activity using agar-based deferred antagonism assays with a range of indicator bacteria. Based on the findings of the screen and subsequent well assays with cell free supernatants and whole cell extracts, one strain, designated CIT060, was selected for further investigation. It was identified as Staphylococcus capitis and herein we describe the purification and characterisation of the novel bacteriocin that the strain produces. This bacteriocin which we have named capidermicin was extracted from the cell-free supernatant of S. capitis CIT060 and purified to homogeneity using reversed-phase high performance liquid chromatography (RP-HPLC). Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometric (MS) analysis revealed that the capidermicin peptide has a mass of 5,464 Da. Minimal inhibitory concentration (MIC) experiments showed that capidermicin was active in the micro-molar range against all the Gram-positive bacteria that were tested. Antimicrobial activity was retained over a range of pHs (2–11) and temperatures (10–121°C x 15 mins). The draft genome sequence of S. capitis CIT060 was determined and the genes predicted to be involved in the biosynthesis of capidermicin were identified. These genes included the predicted capidermicin precursor gene, and genes that are predicted to encode a membrane transporter, an immunity protein and a transcriptional regulator. Homology searches suggest that capidermicin is a novel member of the family of class II leaderless bacteriocins.

Virulence Factors in Coagulase-Negative Staphylococci

“…Likewise, other CoNS produce other important lantibiotics such as gallidermin (S. gallinarium) [425], hominicin [426] and nukacin KQU-131 [427] (S. hominis), nukacin ISK-1 [428] and SWLP1 [429] (S. warneri), nukacin 3299 [430] (S. simulans), and Nisin J [431] (S. capitis). However, CoNS also produce bacteriocins belonging to other classes such as the epidermicin NI01 (produced by S. epidermidis) [432] and capidermicin (S. capitis) [433], which belong to class II, and endopeptidade ALE-1 (S. capitis) and lysostaphin (S. simulans) [434] that belong to class III bacteriocins. Because (i) several staphylococcins target clinically important pathogens such as S. aureus, including methicillin-resistant and vancomycin-intermediate, (ii) the shortage in novel and efficient antibiotics, (iii) the increase in antibiotic resistance, and (iv) the lower toxic effect of bacteriocins when compared to antibiotics [406], the potential use of staphylococcins against both human and animal pathogens has been particularly explored (reviewed in [408,409]).…”

“…Because (i) several staphylococcins target clinically important pathogens such as S. aureus, including methicillin-resistant and vancomycin-intermediate, (ii) the shortage in novel and efficient antibiotics, (iii) the increase in antibiotic resistance, and (iv) the lower toxic effect of bacteriocins when compared to antibiotics [406], the potential use of staphylococcins against both human and animal pathogens has been particularly explored (reviewed in [408,409]). Despite the promising results obtained in vitro, both in planktonic and biofilm modes of growth [426,431,[433][434][435][436], only a few staphylococcins, namely lysostaphin [437][438][439] and epidermicin NI01 [440,441], were evaluated using in vivo models. These two bacteriocins constitute promising candidates as therapeutic antimicrobial agents, lysostaphin currently being in late clinical trials for topical application [409].…”

Living in Your Skin: Microbes, Molecules, and Mechanisms

“…2 ). Bacteriocins, which are ribosomally synthesized, heat-resistant, and highly potent molecules that often inhibit the growth of closely related bacterial species ( 105 ), have been identified to be produced by numerous CoNS species ( 19 , 106 – 109 ) and are likely produced by the majority of skin commensals. S. epidermidis produces numerous bacteriocins and phenol-soluble modulins that selectively kill skin pathogens but are not active against S. epidermidis itself ( 110 ).…”

Bacteriocins: An Overview of Antimicrobial, Toxicity, and Biosafety Assessment by in vivo Models

“…The formulation had a significant antibacterial effect and animals showed no changes of behavior or obvious toxic effects ( Ovchinnikov et al, 2020 ). Therefore, there is a growing interest for the study of the therapeutic properties and side effects of bacteriocins using in vivo systems ( Abanoz and Kunduhoglu, 2018 ; Bagci et al, 2019 ; Iseppi et al, 2019 ; Lynch et al, 2019 ; Lajis, 2020 ; Meade et al, 2020 ).…”