Green synthesis of silver nanoparticles using keratinase obtained from a strain of Bacillus safensis LAU 13

Abstract

In this study, crude extracellular keratinase obtained from a novel keratin-degrading bacterial strain, Bacillus safensis LAU 13 (GenBank accession No. KJ461434) was used for the synthesis of silver nanoparti- cles (AgNPs). The particles were characterised by UV– Visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and transmission electron microscopy. The biosynthesised AgNPs exhibited maximum absorbance at 409 nm. They are spherical in shape with the size ranging 5–30 nm. The FTIR spectrum showed peaks at 3410, 2930, 1664, 1618, 1389 and 600 cm-1, indicating that proteins were the capping and stabilisation molecules in the syn- thesis of AgNPs. Data obtained from XRD showed that the particles have face-centred cubic phase and are crystalline in nature with average size of *8.3 nm. The particles showed effective inhibitory activity against five clinical isolates of Escherichia coli. Therefore, the keratinase of this strain could be used to develop an environmental friendly method for the rapid synthesis of AgNPs. To the best of our knowledge, this is the first report of green synthesis of AgNPs using the metabolite of B. safensis, and the report adds to the growing relevance of B. safensis as a potential industrially viable organism. Keywords