Composition of the Biofilm Matrix of Cutibacterium acnes Acneic Strain RT5

Abstract

In skin, Cutibacterium acnes (former Propionibacterium acnes ) can behave as an opportunistic pathogen, depending on the strain and environmental conditions. Acneic strains of C. acnes form biofilms inside skin–gland hollows, inducing inflammation and skin disorders. The essential exogenous products of C. acnes accumulate in the extracellular matrix of the biofilm, conferring essential bacterial functions to this structure. However, little is known about the actual composition of the biofilm matrix of C. acnes . Here, we developed a new technique for the extraction of the biofilm matrix of Gram-positive bacteria without the use of chemical or enzymatic digestion, known to be a source of artifacts. Our method is based on the physical separation of the cells and matrix of sonicated biofilms by ultracentrifugation through a CsCl gradient. Biofilms were grown on the surface of cellulose acetate filters, and the biomass was collected without contamination by the growth medium. The biofilm matrix of the acneic C. acnes RT5 strain appears to consist mainly of polysaccharides. The following is the ratio of the main matrix components: 62.6% polysaccharides, 9.6% proteins, 4.0% DNA, and 23.8% other compounds (porphyrins precursors and other). The chemical structure of the major polysaccharide was determined using a nuclear magnetic resonance technique, the formula being →6)-α- D -Gal p -(1→4)-β- D -Man p NAc3NAcA-(1→6)-α- D -Glc p -(1→4)-β- D -Man p NAc3NAcA-(1→3)-β-Gal p NAc-(1→. We detected 447 proteins in the matrix, of which the most abundant were the chaperonin GroL, the elongation factors EF-Tu and EF-G, several enzymes of glycolysis, and proteins of unknown function. The matrix also contained more than 20 hydrolases of various substrata, pathogenicity factors, and many intracellular proteins and enzymes. We also performed surface-enhanced Raman spectroscopy analysis of the C. acnes RT5 matrix for the first time, providing the surface-enhanced Raman scattering (SERS) profiles of the C. acnes RT5 biofilm matrix and biofilm biomass. The difference between the matrix and biofilm biomass spectra showed successful matrix extraction rather than simply the presence of cell debris after sonication. These data show the complexity of the biofilm matrix composition and should be essential for the development of new anti- C. acnes biofilms and potential antibiofilm drugs.

Porphyrins produced by acneic Cutibacterium acnes strains activate the inflammasome by inducing K+ leakage

“…Third, little is known about concentration of porphyrins inside the sebaceous gland and in sebum, and it remains to be seen whether the concentrations of porphyrins used in the present study are physiologically relevant ( Borelli et al., 2006 ; Gannesen et al., 2019 ).…”

Epinephrine affects gene expression levels and has a complex effect on biofilm formation in Micrococcus luteus strain C01 isolated from human skin

“…Also, a potential decrease in the GroES cochaperone may also be a factor in biofilm growth inhibition [ 67 , 68 ]. Additionally, the downregulated co-chaperone GroES of M. luteus has 74.5% similarity with the GroS cochaperone of Cutibacterium acnes HL043PA2, which is one of the major protein components of the biofilm matrix of C. acnes HL043PA2 [ 69 ]. This finding enables us to suggest the involvement of this protein in biofilm inhibition.…”

Acne and Stress: Impact of Catecholamines on Cutibacterium acnes

“…However, the cytotoxicity studies were performed using planktonic bacteria, as growing biofilms on cultured cells was not possible. As recently shown, the matrix of C. acnes contains highly diverse molecules, which can affect the viability of eukaryotic cells (40), and biofilm matrix is frequently considered itself to be a virulence factor (41). In addition, C. acnes virulence factor expression can be modulated by the microenvironment (27) and generally requires the contribution of host molecules, such as acid sphingomyelinase (42).…”