title: Antibacterial mode of action of violacein from Chromobacterium violaceum UTM5 against Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA).
abstract: Violacein, violet pigment produced by Chromobacterium violaceum, has attracted much attention recently due to its pharmacological properties including antibacterial activity. The present study investigated possible antibacterial mode of action of violacein from C. violaceum UTM5 against Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) strains. Violet fraction was obtained by cultivating C. violaceum UTM5 in liquid pineapple waste medium, extracted, and fractionated using ethyl acetate and vacuum liquid chromatography technique. Violacein was quantified as major compound in violet fraction using HPLC analysis. Violet fraction displayed bacteriostatic activity against S. aureus ATCC 29213 and methicillin-resistant S. aureus ATCC 43300 with minimum inhibitory concentration (MIC) of 3.9 μg/mL. Fluorescence dyes for membrane damage and scanning electron microscopic analysis confirmed the inhibitory effect by disruption on membrane integrity, morphological alternations, and rupture of the cell membranes of both strains. Transmission electron microscopic analysis showed membrane damage, mesosome formation, and leakage of intracellular constituents of both bacterial strains. Mode of action of violet fraction on the cell membrane integrity of both strains was shown by release of protein, K+, and extracellular adenosine 5'-triphosphate (ATP) with 110.5 μg/mL, 2.34 μg/mL, and 87.24 ng/μL, respectively, at 48 h of incubation. Violet fraction was toxic to human embryonic kidney (HEK293) and human fetal lung fibroblast (IMR90) cell lines with LC50value of 0.998 ± 0.058 and 0.387 ± 0.002 μg/mL, respectively. Thus, violet fraction showed a strong antibacterial property by disrupting the membrane integrity of S. aureus and MRSA strains. This is the first report on the possible mode of antibacterial action of violet fraction from C. violaceum UTM5 on S. aureus and MRSA strains.
authors.affiliation: Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, UTM, 81310, Johor Bahru, Johor, Malaysia.
authors.forename: Claira Arul
authors.initials: CA
authors.lastname: Aruldass
authors.affiliation: Electron Microscopy Unit, Institute for Medical Research, Jalan Pahang, 50588, Kuala Lumpur, Malaysia.
authors.forename: Santhana Raj Louis
authors.initials: SRL
authors.lastname: Masalamany
authors.affiliation: Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, UTM, 81310, Johor Bahru, Johor, Malaysia.
authors.forename: Chidambaram Kulandaisamy
authors.initials: CK
authors.lastname: Venil
authors.affiliation: Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, UTM, 81310, Johor Bahru, Johor, Malaysia. azlina@kimia.fs.utm.my.
authors.forename: Wan Azlina
authors.initials: WA
authors.lastname: Ahmad
mesh_terms: D000900:Anti-Bacterial Agents / Q000302:isolation & purification / Q000494:pharmacology* / Q000633:toxicity; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000648:ultrastructure; D002470:Cell Survival / Q000187:drug effects; D002861:Chromobacterium / Q000737:chemistry*; D057809:HEK293 Cells; D006801:Humans; D007211:Indoles / Q000302:isolation & purification / Q000494:pharmacology* / Q000633:toxicity; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects* / Q000648:ultrastructure; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability / Q000187:drug effects; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000648:ultrastructure
chemical_list: D000900:Anti-Bacterial Agents; D007211:Indoles; C063155:violacein
keywords: Antibacterial mechanism; MRSA; Membrane damage; Membrane integrity; S. aureus; Violacein