title: Purification and optimization of production conditions of a marine-derived antibiotic and ultra-structural study on the effect of this antibiotic against MRSA.
abstract: OBJECTIVE
  In this study we have attempted to partially purify, characterize and optimize the fermentation condition for the antimicrobial compound production with anti-MRSA (Methicillin Resistant Staphylococcus aureus) activity produced by Pseudoalteromonas piscicida PG-02 bacterium, isolated from the Persian Gulf, and finally understand the morphological changes in MRSA due to this antibiotic.
  
  
  METHODS
  Optimization process of antibacterial compound production was studied based on the sources of carbon and nitrogen, optimum temperature, optimum pH and optimum incubation time. The purification of intended antibiotic was done using TLC and also thermostability and enzymatic stability treatment was studied. Ultrastructural study on the effect of intended antibacterial compound on MRSA was done using a Transmission Electron Microscopy (TEM).
  
  
  RESULTS
  The optimized bioprocess conditions for the maximum production were at temperature 28 degrees C, pH 7, NaCI 0.5% (w/v), 96 hrs (incubation time), glucose and tryptone as carbon source and nitrogen source, respectively. The antibacterial component showed thermal sensitivity but it was sensitive to proteinase K, so this compound may have proteinaceous nature. The results of sonication revealed that this compound is accumulated in both intra- and extra-cellular locations. TEM pictures showed disorganization of cytoplasmic membrane upon the extract treatment comparing to control so, it can be said that this antibacterial compound can be considered as a bactericidal agent against MRSA.
  
  
  CONCLUSIONS
  On the basis of obtained results, this bacterium can be regarded as a valuable strain for discovery of new weapon as bactericidal agent in fighting against multi-drug resistant bacteria especially MRSA.
authors.affiliation: Department of Biology, Faculty of Science, Shahid Chamran University, Ahvaz, Iran. ismal_dar@yahoo.com
authors.forename: E
authors.initials: E
authors.lastname: Darabpour
authors.forename: M
authors.initials: M
authors.lastname: Roayaei Ardakani
authors.forename: H
authors.initials: H
authors.lastname: Motamedi
authors.forename: M T
authors.initials: MT
authors.lastname: Ronagh
authors.forename: H
authors.initials: H
authors.lastname: Najafzadeh
mesh_terms: D000900:Anti-Bacterial Agents / Q000096:biosynthesis* / Q000494:pharmacology*; D003470:Culture Media; D006863:Hydrogen-Ion Concentration; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects* / Q000648:ultrastructure; D008826:Microbial Sensitivity Tests; D046529:Microscopy, Electron, Transmission; D031161:Pseudoalteromonas / Q000737:chemistry*; D012623:Seawater / Q000382:microbiology; D012997:Solvents; D013696:Temperature; D014465:Ultrasonics
chemical_list: D000900:Anti-Bacterial Agents; D003470:Culture Media; D012997:Solvents