title: Transcriptional and functional analysis of the effects of magnolol: inhibition of autolysis and biofilms in Staphylococcus aureus.
abstract: BACKGROUND
  The targeting of Staphylococcus aureus biofilm structures are now gaining interest as an alternative strategy for developing new types of antimicrobial agents. Magnolol (MOL) shows inhibitory activity against S. aureus biofilms and Triton X-100-induced autolysis in vitro, although there are no data regarding the molecular mechanisms of MOL action in bacteria.
  
  
  RESULTS
  The molecular basis of the markedly reduced autolytic phenotype and biofilm inhibition triggered by MOL were explored using transcriptomic analysis, and the transcription of important genes were verified by real-time RT-PCR. The inhibition of autolysis by MOL was evaluated using quantitative bacteriolytic assays and zymographic analysis, and antibiofilm activity assays and confocal laser scanning microscopy were used to elucidate the inhibition of biofilm formation caused by MOL in 20 clinical isolates or standard strains. The reduction in cidA, atl, sle1, and lytN transcript levels following MOL treatment was consistent with the induced expression of their autolytic repressors lrgA, lrgB, arlR, and sarA. MOL generally inhibited or reversed the expression of most of the genes involved in biofilm production. The growth of S. aureus strain ATCC 25923 in the presence of MOL dose-dependently led to decreases in Triton X-100-induced autolysis, extracellular murein hydrolase activity, and the amount of extracellular DNA (eDNA). MOL may impede biofilm formation by reducing the expression of cidA, a murein hydrolase regulator, to inhibit autolysis and eDNA release, or MOL may directly repress biofilm formation.
  
  
  CONCLUSIONS
  MOL shows in vitro antimicrobial activity against clinical and standard S. aureus strains grown in planktonic and biofilm cultures, suggesting that the structure of MOL may potentially be used as a basis for the development of drugs targeting biofilms.
authors: Key Laboratory of Zoonosis, Ministry of Education, Institute of Zoonosis, College of Animal Science and Veterinary Medicine, Jilin University, Changchun, People's Republic of China.
authors: Dacheng
authors: D
authors: Wang
authors: Qi
authors: Q
authors: Jin
authors: Hua
authors: H
authors: Xiang
authors: Wei
authors: W
authors: Wang
authors: Na
authors: N
authors: Guo
authors: Kaiyu
authors: K
authors: Zhang
authors: Xudong
authors: X
authors: Tang
authors: Rizeng
authors: R
authors: Meng
authors: Haihua
authors: H
authors: Feng
authors: Lihui
authors: L
authors: Liu
authors: Xiaohong
authors: X
authors: Wang
authors: Junchao
authors: J
authors: Liang
authors: Fengge
authors: F
authors: Shen
authors: Mingxun
authors: M
authors: Xing
authors: Xuming
authors: X
authors: Deng
authors: Lu
authors: L
authors: Yu
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001329:Autolysis / Q000139:chemically induced*; D001433:Bacteriolysis / Q000187:drug effects; D018441:Biofilms / Q000187:drug effects*; D001713:Biphenyl Compounds / Q000494:pharmacology*; D017705:Lignans / Q000494:pharmacology*; D017830:Octoxynol; D013211:Staphylococcus aureus / Q000187:drug effects*; D059467:Transcriptome
chemical_list: D000900:Anti-Bacterial Agents; D001713:Biphenyl Compounds; D017705:Lignans; C005498:magnolol; D017830:Octoxynol