Streptomyces ‐derived actinomycin D inhibits biofilm formation via downregulating ica locus and decreasing production of PIA in Staphylococcus epidermidis

Abstract

Aim The objective of this study was to investigate the biofilm inhibitory activity of Streptomyces‐derived actinomycin D against biofilm formation by Staphylococcus epidermidis. Methods and Results The microtitre plate method and microscopy were used to detect the biofilm formation of S. epidermidis. And an attempt was made to detect the effect of actinomycin D on important biofilm components, exopolysaccharides (EPS) in S. epidermidis using precolumn derivation HPLC. Also cell surface hydrophobicities of S. epidermidis were assessed to explore action mechanisms. The qPCR was performed to demonstrate the genetic mechanisms of biofilm formation by S. epidermidis. Unlike other antibiotics, actinomycin D (1·5 μg ml−1) from Streptomyces luteus significantly inhibited biofilm formation by S. epidermidis. Additionally, it effectively inhibited S. epidermidis cells from adhering to glass slides. Actinomycin D downregulated ica locus and then the reduced polysaccharide intercellular adhesin production caused S. epidermidis cells to become less hydrophobic, thus supporting its anti‐biofilm effect. Conclusion Streptomyces‐derived actinomycin D is active in inhibiting the biofilm formation of S. epidermidis. Significance and Impact of the Study Actinomycin D can be used as a promising antibiofilm agent in inhibiting S. epidermidis biofilm formation. The study is also the first insight into how actinomycin D inhibited the biofilm formation of S. epidermidis. Actinomycin D could potentially be used to reduce the risk of biofilm‐associated infections. Our study also suggests that the metabolites from Actinomycete strains keep further attention as potential antibiofilm agents against biofilm formation of S. epidermidis, even biofilm infections of the other bacteria.

Quercetin Inhibits Biofilm Formation by Decreasing the Production of EPS and Altering the Composition of EPS in Staphylococcus epidermidis

“…A static biofilm formation assay was performed using 96well polystyrene plates as previously described, with slight modifications (Pratt and Kolter, 1998;Xie et al, 2019;Mu et al, 2020). Briefly, cells were diluted 1:100 with fresh TSB and cultured with different concentrations of quercetin (0-1,000 µg ml −1 ) for 24 h without shaking at 37 • C. Biofilms were stained with crystal violet (Sigma, C3886) and dissolved in 95% ethanol (0.5%, w/v).…”

“…Biofilms grown on glass slides were stained with crystal violet and were visualized by light microscopy (Nikon Eclipse Ti 100) at a magnification of ×400 (Nithyanand et al, 2010;Xie et al, 2019;Mu et al, 2020). SEM was used to observe biofilm cells as previously described (Lee et al, 2016).…”

“…Pre-column derivation high-performance liquid chromatography (HPLC) was used to detect the monosaccharide composition of EPS in S. epidermidis (Zhang et al, 2009;Xie et al, 2019;Mu et al, 2020). Ribose (∼1 mmol, per 50 ml) was used as the internal standard solution.…”

“…Cell surface hydrophobicity was tested as previously described (Rosenberg et al, 1980;Xie et al, 2019;Mu et al, 2020). Briefly, 1 ml of bacteria (OD 400 = 0.6) was placed into glass tubes and 250 µl of n-hexadecane (Macklin, H810865) was added.…”

“…Moreover, the antibiotic therapy against pathogenic bacteria is currently decreasing, which is partly attributed to biofilm formation (Al-Yousef et al, 2017;Singh et al, 2017). Consequently, the ability of biofilm formation by S. epidermidis is focused on in recent years (Vadyvaloo and Otto, 2005;Xie et al, 2019;Mu et al, 2020).…”