Comparative analysis of biologically synthesized silver nanoparticles by pathogenic and non-pathogenic bacteria and their applications

Biosynthesis of silver nano particles using biological micro-organisms such as bacteria is considered a green technology, as it does not involve any harmful chemicals, physical and chemical processes. The present study reports the synthesis of silver nanoparticles (Ag NPs) from silver nitrate solution by pathogenic bacteria named as Pseudomonas aeruginosa and E. coli (MTCC 1195) non-pathogenic bacteria. AgNPs were characterized by UV–vis spectrophotometer and Scanning electron microscope (SEM). According to SEM and UV-vis spectrophotometric analysis, silver nano particles synthesized by Pseudomonas aeruginosa and E. coli (MTCC 1195) are 5 and 10 nm in size. AgNPs possess potential to exhibit antimicrobial, larvicidal, DNA photocleavage activities and are also involved in catalytic degradation of organic dyes. Antimicrobial activity of Ag NPs (0.52 and 1 ppm) synthesized from Pseudomonas aeruginosa and E. coli (MTCC 1195) is observed againstE. coli (Z.O.I of 11, 12 mm and 10, 11 mm).Larvicidal activity of Ag NPS was tested against third instar larvae of Drosophila melanogaster. LC50 and LC90 is achieved by AgNPs synthesized from Pseudomonas aeruginosa and LC60 and LC30 by AgNPs synthesized from E. coli (MTCC 1195) at 1 and 2 ppm. AgNPs exhibits enormous potential to degrade organic dyes namely Rhodamine B, Safranine, Bromophenol blue and Trypan blue. Rate of degradation of Rhodamine B, Safranine, Bromophenol blue and Trypan blue is observed to be 27, 83, 10.57, and 5.3% by AgNPs synthesized from Pseudomonas aeruginosa and 25, 79, 8.25 and 4.8% by AgNPs synthesized from E. coli (MTCC 1195). AgNPs synthesized from Pseudomonas aeruginosa and E. coli (MTCC 1195) shows a significant DNA photocleavage activity against pUC 18 at concentration of 131 and 175 ppb. Silver nano particles synthesized by pathogenic Pseudomonas aeruginosa exhibits better biological activities in comparison to AgNPs synthesized from E. coli (MTCC 1195).