An Approach towards Continuous Production of Silver Nanoparticle Using Bacillus Thuringiensis

Abstract

Applying the principles of green chemistry for the synthesis of nanoparticles (NPs) is an emerging field of the current era. Continuous production of NPs, i.e. simultaneous bacterial growth and NPs production, if possible, would be more effective for different NPs mediated applications. Hence, our approach here is to optimize the method to produce and extract silver nanoparticle (AgNP) during growth of the bacteria, Bacillus thuringiensis. The fabricated AgNP was obtained when the bacteria were grown at minimum inhibitory concentration of AgNO3 in culture medium. The microorganism produced elemental silver NP with particular surface physico-chemical properties pertaining to the cellular moieties acting as a capping agent. Fabrication of the NP was confirmed in UV-Vis absorbance spectra, attenuated total reflection fourier transform infrared spectra, zeta analysis, and field emission scanning electron micrographs. The UV-Vis and IR studies together indicated the presence of proteins on the NP surface. The fabricated NPs were further purified using size exclusion chromatograph (SEC), and the presence of NP in different elutions was further confirmed using the UV-Vis, IR spectroscopes, and TEM. The yield, upon purification, was 98.75 µg AgNP from 500 mL of the culture, which is relatively good yield. Additionally, the purified AgNP was found to have relatively stronger antibacterial activity against Escherichia coli than commercially available AgNP. The work shows that the microorganism with resistance to significant concentrations of metal ions can be used for continuous production of metal NPs for industrial as well as biological applications.