title: Synthesis of silver nanoparticles by endosymbiont Pseudomonas fluorescens CA 417 and their bactericidal activity.
abstract: The present study emphasizes on biogenic synthesis of silver nanoparticles and their bactericidal activity against human and phytopathogens. Nanoparticle synthesis was performed using endosymbiont Pseudomonas fluorescens CA 417 inhabiting Coffea arabica L. Synthesized nanoparticles were characterized using hyphenated spectroscopic techniques such as UV-vis spectroscopy which revealed maximum absorption 425nm. Fourier transform infrared spectroscopy (FTIR) analysis revealed the possible functional groups mediating and stabilizing silver nanoparticles with predominant peaks occurring at 3346 corresponding to hydroxyl group, 1635 corresponding carbonyl group and 680 to aromatic group. X-ray diffraction (XRD) analysis revealed the Bragg's diffraction pattern with distinct peaks at 38° 44°, 64° and 78° revealing the face-centered cubic (fcc) metallic crystal corresponding to the (111), (200), (220) and (311) facets of the crystal planes at 2θ angle. The energy dispersive X-ray spectroscopy (EDS) analysis revealed presence of high intense absorption peak at 3keV is a typical characteristic of nano-crystalline silver which confirmed the presence of elemental silver. TEM analysis revealed the size of the nanoparticles to be in the range 5-50nm with polydisperse nature of synthesized nanoparticles bearing myriad shapes. The particle size determined by Dynamic light scattering (DLS) method revealed average size to be 20.66nm. The synthesized silver nanoparticles exhibited significant antibacterial activity against panel of test pathogens. The results showed Klebsiella pneumoniae (MTCC 7407) and Xanthomonas campestris to be more sensitive among the test human pathogen and phyto-pathogen respectively. The study also reports synergistic effect of silver nanoparticles in combination with kanamycin which displayed increased fold activity up to 58.3% against Klebsiella pneumoniae (MTCC 7407). The results of the present investigation are promising enough and attribute towards growing scientific knowledge on development of new antimicrobial agents to combat drug resistant microorganisms. The study provides insight on emerging role of endophytes towards reduction of metal salts to synthesize nanoparticles.
authors.affiliation: Bionanotechnological Laboratory, Department of Studies in Microbiology, University of Mysore, Manasagangotri, Mysore, India; Laboratory of Biotechnology of New Materials, Siberian Federal University, Siberia, Russia.
authors.forename: Baker
authors.initials: B
authors.lastname: Syed
authors.affiliation: Department of Biotechnology, JSS Science and Technology University, JSS Technical Institutional Campus, Mysore 570006, India.
authors.forename: Nagendra Prasad
authors.initials: NP
authors.lastname: M N
authors.affiliation: Toxicology and Drug Discovery Unit, Centre for Emerging Technologies (CET), Jain University, Ramanagara, 562 112, India.
authors.forename: Dhananjaya
authors.initials: D
authors.lastname: B L
authors.affiliation: Universidad Nacional Autonoma de Mexico, Instituto de Ciencias Fisicas, Avenida Universidad s/n, 62210, Cuernavaca, MOR, Mexico; Department of Chemistry, Madanapalle Institute of Technology & Science, Post Box No: 14, Kadiri Road, Angallu (V), Madanapalle, 517325, Chittoor District, Andhra Pradesh, India.
authors.forename: Mohan Kumar
authors.initials: MK
authors.lastname: K
authors.affiliation: BMS R and D Centre, BMS College of Engineering, Bangalore 560 019, India.
authors.forename: Yallappa
authors.initials: Y
authors.lastname: S
authors.affiliation: Bionanotechnological Laboratory, Department of Studies in Microbiology, University of Mysore, Manasagangotri, Mysore, India. Electronic address: satish.micro@gmail.com.
authors.forename: Satish
authors.initials: S
authors.lastname: S
mesh_terms: D000900:Anti-Bacterial Agents / Q000378:metabolism* / Q000494:pharmacology*; D001709:Biotechnology; D040503:Coffea / Q000382:microbiology; D060026:Endophytes / Q000145:classification / Q000378:metabolism; D055772:Green Chemistry Technology; D006801:Humans; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D008826:Microbial Sensitivity Tests; D036103:Nanotechnology; D011551:Pseudomonas fluorescens / Q000145:classification / Q000378:metabolism*; D012834:Silver / Q000737:chemistry* / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D012834:Silver
keywords: Antibacterial activity; Coffea arabica L; Endosymbiont; Kanamycin; Pseudomonas fluorescens CA 417; Silver nanoparticles