Open AccessAg/SiO2 nanocomposite mediated by Escherichia coli D8 and their antimicrobial potential
Author(s) -
Mohamed M. ElZahed,
Mohamed Abou-Dobara,
Ahmed El-Sayed,
Zakaria A. M. Baka
Publication year - 2022
Publication title -
nova biotechnologica et chimica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.212
H-Index - 9
eISSN - 1339-004X
pISSN - 1338-6905
DOI - 10.36547/nbc.1023
Subject(s) - antimicrobial , chemistry , bacillus cereus , silver nanoparticle , minimum inhibitory concentration , candida albicans , escherichia coli , nuclear chemistry , nanocomposite , fourier transform infrared spectroscopy , botrytis cinerea , antibacterial activity , minimum bactericidal concentration , microbiology and biotechnology , bacteria , nanoparticle , biochemistry , nanotechnology , organic chemistry , materials science , biology , chemical engineering , botany , genetics , engineering , gene
Silica (SiO2) has a fundamental role in the recuperation of plants in response to environmental stresses, besides the induction of resistance against plant diseases. Silver nanoparticles (AgNPs) have a superior antimicrobial activity. The combination between SiO2 and AgNPs is a promising approach due to their antimicrobial activity, biological activity, low toxicity, and high stability of the produced nanocomposite. The current study postulated a green method for silver/silica nanocomposite (Ag/SiO2NC) synthesis at room temperature using the crude metabolites of Escherichia coli D8 (MF062579) strain in the presence of sunlight. UV-Vis spectrophotometry, X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FTIR), and transmission electron microscopy (TEM) analyses have characterized the biosynthesized nanocomposite. TEM study of Ag/SiO2NC showed an average particle size of ~32 – 48 nm whereas AgNPs showed a mean size of 18 – 24 nm. The negative charged Ag/SiO2NC (-31.0 mV) showed potent antimicrobial activity against Bacillus cereus ATCC6633, Klebsiella pneumoniae ATCC33495, Staphylococcus aureus (ATCC25923), E. coli (ATCC25922), Candida albicans (ATCC10231), and Botrytis cinerea (Pers: Fr.). The minimum inhibitory concentration (MIC) test showed a dose-dependent manner of Ag/SiO2NC antimicrobial action. MIC values of Ag/SiO2NC against the tested pathogens exhibited 125 and 6.25 μg.mL-1 as antibacterial and antifungal agents, respectively. TEM micrographs showed changes in the pathogens treated with Ag/SiO2NC including wrinkling, damage, and rupture of the bacterial cell membrane. In addition, the formation of a mucilage matrix connecting the hyphal cells, the appearance of big vacuoles and lipid droplets with severe leakage of cytoplasmic contents of the treated B. cinerea were also recorded.