Growth Phase-Dependent Synthesis of Gold Nanoparticles Using Bacillus Licheniformis

Abstract

Biological agents play an important role in biosynthesis of nanoparticles and regarded as green technology and environmental-friendly approach, which is an important step in the field of application of nanotechnology. The present study reports biosynthesis of gold nanoparticles from gold precursor using Bacillus licheniformis at 37 °C depending upon its growth phase. Growth phase study of bacteria was performed and biosynthesis of gold nanoparticles was carried out at early log phase, mid log phase, stationary phase, and decline phase. The synthesis of gold nanoparticles was confirmed by UV–visible spectrum that showed peak between 545 and 559 nm which was later reconfirmed by SEM studies. Size of gold nanoparticles as measured by dynamic light scattering was found to be in the range of 16–95 nm. Zeta potential measurement showed that gold nanoparticles were negatively charged with zeta potential value between −20.8 and −25.8 mV. The stationary phase culture, out of early and late log phase showed best results, synthesizing small-sized gold nanoparticles.