Biosynthesis of silver nanoparticles by a new strain of Streptomyces sp. compared with Aspergillus                      fumigatus.
Locally isolated strains of a thermoalkalotolerant Streptomyces sp. and Aspergillus fumigatus were used for the in vitro biosynthesis of silver nanoparticles from AgNO(3) solutions. An autolysed cell-free culture filtrate from each strain was used, indicating that the formation mechanism depends on intra-cellular components for both organisms, since culture broths had no significant nanoparticle formation potential. Nanoparticle formation was indicated by a change of the solution from colourless or light brown to dark brown after 24 h or more, and UV-visible spectroscopy and x-ray diffraction analysis confirmed the formation by both organisms. The initial formation kinetics were faster with Aspergillus, but formation continued for a longer period with Streptomyces, resulting in higher concentrations after 48 h. Transmission electron microscope images revealed well dispersed nanoparticles with diameters ranging from 15 to 45 nm from A. fumigatus, while those from Streptomyces sp. had a narrower size distribution of 15-25 nm. The higher productivity and preferred narrower size distribution of Streptomyces, together with its well established industrial use, may make it the preferred choice for further optimization studies.
Engineering Technology, Biotechnology Program, McMaster University, Hamilton, ON, Canada.
Faiez
F
Alani
Murray
M
Moo-Young
William
W
Anderson
D001232:Aspergillus fumigatus / Q000378:metabolism*; D007700:Kinetics; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles / Q000648:ultrastructure*; D012834:Silver / Q000378:metabolism*; D012835:Silver Nitrate / Q000378:metabolism; D013057:Spectrum Analysis; D013302:Streptomyces / Q000378:metabolism*; D013997:Time Factors; D014961:X-Ray Diffraction
D012834:Silver; D012835:Silver Nitrate