SYNTHESIS OF SILVER NANOPARTICLES FROM PSEUDOMONAS PUTIDA NCIM 2650 IN SILVER NITRATE SUPPLEMENTED GROWTH MEDIUM AND OPTIMIZATION USING RESPONSE SURFACE METHODOLOGY

Abstract

The environmental friendly process of silver nanoparticles synthesis using various biological systems was reported earlier. The bacterial strain was selected for study due to its ease of manipulation and maintenance. The present work focuses on the biosynthesis and optimization of silver nanoparticles using the bacterial strain Pseudomonas putida NCIM 2650. The bacterial strain, Pseudomonas putida is a gram negative facultative bacterium that has been certified as a biosafety host and also reported in bioremediation process. Pseudomonas putida NCIM 2650 was explored on silver nitrate (1mM) supplemented growth media and the silver nanoparticle synthesis was carried out. The extracellular nitrate reductase enzyme was assayed for the synthesis of silver nanoparticles; the activity of the enzyme was found to be 0.958 U/ml/min. The growth of an organism was monitored and transformation of silver nanoparticles was started from 22h to 48h. The biosynthesis of silver nanoparticles were optimized using Response Surface Methodology, the statistical tool which has the designs of experiments. The optimum synthesis was observed at 48 h, the optimum temperature was found to be at 37.5°C and pH of 6. The silver nanoparticles were characterized by UV spectroscopy, ICP-OES, Fourier transform infrared spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) confirmed the presence of silver nanoparticles crystals and the size of the silver nanoparticle by particle size analyze+r was found have uniform size of 70nm.