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Analysis of antimicrobial silver nanoparticles synthesized by coastal strains of Escherichia coli and Aspergillus niger

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The present study investigated the extracellular biosynthesis of antimicrobial silver nanoparticles by Escherichia coli AUCAS 112 and Aspergillus niger AUCAS 237 derived from coastal mangrove sediment of southeast India. Both microbial species were able to produce silver nanoparticles, as confirmed by X-ray diffraction spectrum. The nanoparticles synthesized were mostly spherical, ranging in size from 5 to 20 nm for E. coli and from 5 to 35 nm for A. niger, as evident by transmission electron microscopy. Fourier transform spectroscopy revealed prominent peaks corresponding to amides I and II, indicating the presence of a protein for stabilizing the nanoparticles. Electrophoretic analysis revealed the presence of a prominent protein band with a molecular mass of 45 kDa for E. coli and 70 kDa for A. niger. The silver nanoparticles inhibited certain clinical pathogens, with antibacterial activity being more distinct than antifungal activity. The antimicrobial activity of E. coli was more pronounced than that of A. niger and was enhanced with the addition of polyvinyl alcohol as a stabilizing agent. This work highlighted the possibility of using microbes of coastal origin for synthesis of antimicrobial silver nanoparticles.

Cette étude visait à examiner la synthèse extracellulaire de nanoparticules d’argent antimicrobiennes par Escherichia coli AUCAS 112 et Aspergillus niger AUCAS 237 issus de sédiments de mangrove côtière du sud-est de l’Inde. Les deux espèces microbiennes pouvaient produire des nanoparticules d’argent, tel que confirmé le spectre de diffraction de rayons-X. Les nanoparticules synthétisées étaient principalement sphériques, dont la taille allait de 5 à 20 nm chez E. coli et de 5 à 35 nm chez A. niger, selon l’analyse par microscopie électronique par transmission. La spectroscopie à transformée de Fourier a révélé la présence de pics proéminents correspondant aux amides I et II, indiquant la présence d’une protéine qui stabiliserait les nanoparticules. L’analyse en électrophorèse a révélé la présence d’une protéine majeure d’un poids moléculaire de 45 kDa chez E. coli et de 70 kDa chez A. niger. Les nanoparticules d’argent inhibaient certains pathogènes cliniques. L’activité antibactérienne était plus nette que l’activité antifongique. L’activité antimicrobienne était très prononcée chez E. coli et A. niger, et elle était accrue lorsque l’alcool polyvinylique était ajouté comme agent de stabilisation. Ce travail met en évidence la possibilité d’utiliser des microbes d’origine côtière pour synthétiser des nanoparticules d’argent antimicrobiennes.

Document Type: Research Article

Publication date: 2010-12-01

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  • Published since 1954, this monthly journal contains new research in the field of microbiology including applied microbiology and biotechnology; microbial structure and function; fungi and other eucaryotic protists; infection and immunity; microbial ecology; physiology, metabolism and enzymology; and virology, genetics, and molecular biology. It also publishes review articles and notes on an occasional basis, contributed by recognized scientists worldwide.
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