Rapid biosynthesis, Characterization and Antimicrobial Effects of Silver Nanoparticles from microorganism serratia marcescens

Biosynthesised nanoparticles have wider applications in medical and pharmaceutical fields. In our study aims to synthesis silver nanoparticles using biological source Serratia marcescens. The nano particle synthesis was optimized with different pH of the culture medium and concentration of metal salts that affected the nanoparticles formation during synthesis. Culture medium with different pH showed variation in the synthesis of nanoparticles. The absorbance of each sample is recorded and a graph was plotted between pH and absorbance at 420nm. Initially on increasing the pH the nanoparticle synthesis increased gradually up to pH 8. Hence the maximum synthesis of silver nanoparticles was observed at pH 8. The samples with 0.1M silver nitrate concentration showed dark brown colour when compared to the samples with concentration of 0.2M and 0.3M. The bacterial biomass was exposed to silver nitrate the metal ions are reduced to nanoparticles. The observed colour change provided the evidence for nitrogen reductase mediated bio reduction of silver salts to produce nanoparticles. The synthesized AgNps were characterized using UV-visible spectrum, FTIR, AFM. The antibacterial activity of synthesised silver nanoparticles is determined using different Gram negative and Gram positive bacteria. The observed zone of inhibition was measured against Escherichia coli 12 mm, staphylococcus aureus 10 mm, pseudomonas aeruginosa 9 mm. The positively charged AgNps exhibit a greater affinity toward the negatively charged bacterial cells resulting in the microbicidal activity.