Analysis of antimicrobial silver nanoparticles synthesized by coastal strains of Escherichia coli and Aspergillus niger
Authors: SriMahibala Pathmanaban
Kandasamy Kathiresan
Asmathunisha Nabikhan
Nabeel M Alikunhi
Saravanakumar Kandasamy
Journal: Canadian journal of microbiology (2010)
Discipline: MICROBIOLOGY
Keywords: Extracellular biosynthesis; antimicrobial silver nanoparticles; Escherichia coli; Aspergillus niger; coastal mangrove sediment
Affiliations: Centre of advanced study in Marine Biology, Annamalai University, Parangipettai, 608502 Tamil Nadu, India. 

Abstract:  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. 

Retracted: Yes

PubPeer comments:
  Fig. 3. X-ray diffraction pattern of silver nanoparticles synthesized in filtrates of Escherichia coli (A) and Aspergillus niger (B).  Motifs repeat within and between the two putative diffractograms. , 
  Fig. 5. Fourier transform infrared spectrum of silver nanoparticles synthesized in filtrates of Escherichia coli (A) and Aspergillus niger (B). Were these FTIR spectra hand-drawn?  , 
 Figure 6 is a classic of its kind.  SDSu2013PAGE patterns of purified protein of Escherichia coli and Aspergillus niger filtrates added with silver nitrate (SDSu2013 PAGE carried out using 10% polyacrylamide gel containing 0.1% SDS, and stained with 0.1% Coomassie Brilliant Blue R-250 after electrophoresis). Lanes: MARKER, molecular mass marker; ECOL, purified protein extract of E. coli with silver nitrate; AN, purified protein extract of A. niger with silver nitrate.  , 
 Fig 4:  Transmission electron micrograph of silver particles in filtrates of Escherichia coli (A) and Aspergillus niger (B) (scale bar = 50 nm). (Some) repetitions marked.  , 
 #3 Figre 6 seems to have been derived from *[at left]* Fig 8 from [Kathiresan et al (2009)] .  , 
 Figure 4 appears to be part of a series of at least three figures that show remarkable similarities within or between panels and also between papers. Note that the figures are representing very different plant or bacterial extract in each of these studies. * Figure 7 in Nabikhan 2010 doi: 10.1016 j.colsurfb.2010.05.018 * Figure 4 in Kathiresan 2010 doi: 10.1139 w10-094 (this paper) * Figure 3 in Kathiresan 2012 doi: 10.1504 ijbnn.2012.051222  , 
 Figure 4, update: there appears to be an additional overlap between panel A and B.  , 
 #7 In retrospect, it is obvious that the  filtrates of Escherichia coli (A) and Aspergillus niger (B) are enlargements from Fig 3A ( Sesuvium portulacastrum ) from [Kathiresan, Alikunhi Nabikhan (2012)] . Hence the shared details at the corners where the enlargements overlap.  , 
 2020 retraction. https: www.nrcresearchpress.com doi pdfplus 10.1139 cjm-2020-0029?src=recsys Ref.: Can. J. Microbiol. 56(12): 1050u20131059. doi:10.1139 W10-094. The Editors-in-Chief of the Canadian Journal of Microbiology have identified cases of image manipulation and image duplication without permission in this paper. Thus, the Editors-in-Chief have retracted the paper from the Canadian Journal of Microbiology. This decision is in compliance with the publishing policy of the Canadian Journal of Microbiology and its publisher, Canadian Science Publishing ,