title: Biogenesis of antibacterial silver nanoparticles using the endophytic bacterium Bacillus cereus isolated from Garcinia xanthochymus.
abstract: OBJECTIVE
  To synthesize the ecofriendly nanoparticles, which is viewed as an alternative to the chemical method which initiated the use of microbes like bacteria and fungi in their synthesis.
  
  
  METHODS
  The current study uses the endophytic bacterium Bacillus cereus isolated from the Garcinia xanthochymus to synthesize the silver nanoparticles (AgNPs). The AgNPs were synthesized by reduction of silver nitrate solution by the endophytic bacterium after incubation for 3-5 d at room temperature. The synthesis was initially observed by colour change from pale white to brown which was confirmed by UV-Vis spectroscopy. The AgNPs were further characterized using FTIR, SEM-EDX and TEM analyses.
  
  
  RESULTS
  The synthesized nanoparticles were found to be spherical with the size in the range of 20-40 nm which showed a slight aggregation. The energy-dispersive spectra of the nanoparticle dispersion confirmed the presence of elemental silver. The AgNPs were found to have antibacterial activity against a few pathogenic bacteria like Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Salmonella typhi and Klebsiella pneumoniae.
  
  
  CONCLUSIONS
  The endophytic bacteria identified as Bacillus cereus was able to synthesize silver nanoparticles with potential antibacterial activity.
authors.affiliation: Department of Biotechnology, Sathyabama University, Chennai, India.
authors.forename: Swetha
authors.initials: S
authors.lastname: Sunkar
authors.forename: C Valli
authors.initials: CV
authors.lastname: Nachiyar
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D001409:Bacillus cereus / Q000187:drug effects* / Q000302:isolation & purification; D004926:Escherichia coli / Q000187:drug effects; D029760:Garcinia / Q000737:chemistry*; D007711:Klebsiella pneumoniae / Q000187:drug effects; D053768:Metal Nanoparticles / Q000737:chemistry*; D008826:Microbial Sensitivity Tests; D053758:Nanoparticles / Q000737:chemistry; D008517:Phytotherapy / Q000379:methods; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D011550:Pseudomonas aeruginosa / Q000187:drug effects; D012834:Silver / Q000737:chemistry* / Q000494:pharmacology; D013211:Staphylococcus aureus / Q000187:drug effects
chemical_list: D000900:Anti-Bacterial Agents; D010936:Plant Extracts; D012834:Silver
keywords: Antibacterial activity; Bacillus cereus; Endophytic bacteria; SEM; Silver nanoparticles; TEM; UV-Vis spectra