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Alternative sigma factor B (σ^B) and catalase enzyme contribute to Staphylococcus epidermidis biofilm's tolerance against physico-chemical disinfection.

ABSTRACT: Staphylococcus epidermidis is the predominant cause of recalcitrant biofilm-associated infections, which are often highly resistant to antibiotics. Thus, the use of physico-chemical agents for disinfection offers a more effective approach to the control of S. epidermidis biofilm infections. However, the underlying tolerance mechanisms employed by S. epidermidis biofilm against these physico-chemical disinfectants remain largely unknown. The expression of a σ^B-dependent gene, alkaline shock protein 23 (asp23) and catalase activity by S. epidermidis biofilm and planktonic cells exposed to heat (50 °C), 0.8 M sodium chloride (NaCl), 5 mM sodium hypochlorite (NaOCl) or 50 μM hydrogen peroxide (H₂O₂) for 60 minutes were compared. Significantly higher asp23 expression levels were observed in biofilms exposed to 50 °C, 5 mM NaOCl or 50 μM H₂O₂ compared to the corresponding planktonic cells (p < 0.05). Conversely, asp23 expression levels in biofilm and planktonic cells exposed to 0.8 M NaCl were not significantly different (p > 0.05). Further, biofilms exposed to 50 °C, 0.8 M NaCl, 5 mM NaOCl or 50 μM H₂O₂ exhibited significantly higher catalase activity than the planktonic cells (p < 0.05). These results suggest that activities of σ^B and catalase may be involved in the tolerance of S. epidermidis biofilm against physico-chemical disinfection.

SUBMITTER: Olwal CO

PROVIDER: S-EPMC6440968 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundThe highly conserved macromolecular synthesis operon (MMSO) contains both dnaG (primase) and sigA (primary sigma factor). However, in previously evaluated gram-positive species, the MMSO is divergent upstream of dnaG. The MMSO of Bacillus subtilis contains three open reading frames (ORFs) that are differentially regulated by multiple promoters. In conjunction with studies to determine the expression profile of dnaG, the MMSO of Staphylococus epidermidis was characterized.ResultsThe ORFs of S. epidermidis were compared to the previously described MMSO of B. subtilis and two additional ORFs in S. epidermidis, serp1129 and serp1130, were identified. The largest transcript, 4.8 kb in length, was expressed only in exponential growth and encompassed all four ORFs (serp1130, serp1129, dnaG, and sigA). A separate transcript (1.5 kb) comprising serp1130 and serp1129 was expressed in early exponential growth. Two smaller transcripts 1.3 and 1.2 kb in size were detected with a sigA probe in both exponential and post-exponential phases of growth. Western blot analysis correlated with the transcriptional profile and demonstrated that Serp1129 was detected only in the exponential phase of growth. Computational analysis identified that Serp1130 contained a CBS motif whereas Serp1129 contained an ATP/GTP binding motif. Functional studies of Serp1129 demonstrated that it was capable of binding both ATP and GTP. Comparisons with a sigB:dhfr mutant revealed that the 1.3 kb sigA transcript was regulated by a sigma(B)-dependent promoter.ConclusionsThese studies demonstrated that the S. epidermidis 1457 MMSO contains two ORFs (serp1129 and serp1130) not described within the B. subtilis MMSO and at least three promoters, one of which is sigma(beta)-dependent. The transcriptional regulation of sigA by sigma(B) provides evidence that the staphylococcal sigma(B)-dependent response is controlled at both the transcriptional and post-transcriptional level. The conservation of serp1129 across multiple gram-positive organisms and its capability to bind ATP and GTP support the need for further investigation of its role in bacterial growth.

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Alternative sigma factor B (σ^B) and catalase enzyme contribute to Staphylococcus epidermidis biofilm's tolerance against physico-chemical disinfection.

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Dataset Information

Alternative sigma factor B (σB) and catalase enzyme contribute to Staphylococcus epidermidis biofilm's tolerance against physico-chemical disinfection.

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OmicsDI is part of the ELIXIR infrastructure

Tweets

Alternative sigma factor B (σ^B) and catalase enzyme contribute to Staphylococcus epidermidis biofilm's tolerance against physico-chemical disinfection.