Determination of the effective origin source for nanosilver particles produced by Escherichia coli strain S78 and its application as antimicrobial agent

It is known that extracellular biosynthesis of nano-particles could be highly advantageous for its synthesis in large quantities and easy downstream processing. Therefore, the present study aims to specify and determine the effective origin source for Ag-NPs produced by Escherichia coli strain S78, if it was culture broth, supernatant or cell pellet. The reduction of silver nitrate was determined by estimating the excreted amount of the enzyme nitrate reductase. Additionally, the produced silver from the specified corresponding production phase was characterized. Moreover, the antibacterial effect of produced Ag-NPs against both Gram positive and Gram negative bacteria was investigated. The results demonstrated that after 7 days of incubation culture broth produced the highest yield of Ag-NPs followed by the cell-free supernatant. FTIR spectra, nitrate reductase assay and accumulation efficiency confirmed the extracellular production of Ag-NPs. The results also revealed that the produced Ag-NPs has got a good antibacterial activity against Gram negative, when compared with the Gram positive bacteria. In final conclusion, the Ag-NPs produced in the culture broth of strain S78 could be used successfully as an environmental friendly disinfector of water and wastewater against pathogenic microorganisms.

The present study was aiming to specify and determine the effective origin source for Ag-NPs produced by Escherichia coli strain S78, if it is the culture broth, supernatant and/or cells pellet. The reductase enzyme amounts which corresponding for the reduction of silver nitrate was determined. The antibacterial effect of produced Ag-NPs against both Gram positive and Gram negative bacteria was investigated. The results demonstrated that the highest yield of Ag-NPs was obtained in the culture broth followed by cell-free supernatant after 7 days of incubation. The results also revealed that the produced Ag-NPs have good antibacterial activity against Gram negative when compared with the Gram positive bacteria. In final conclusion, the Ag-NPs produced in the culture broth of strain S78 could be used successfully as an environmentally friendly disinfector of water and wastewater against pathogenic microorganisms.Figure optionsDownload as PowerPoint slideHighlights
► The effective origin source for Ag-NPs produced by Escherichia coli strain S78 was tested.
► The reductase enzyme amounts responsible for silver reduction were determined.
► The Ag-NPs from the specified corresponding production phase was characterized.
► Highest yield of Ag-NPs was attained in the culture broth after 7 days of incubation.
► The produced Ag-NPs have a good antibacterial activity.