Optimization of the biosynthesis of silver nanoparticles using bacterial extracts and their antimicrobial potential

•The AgNPs were synthesized using bacterial supernatant and intracellular extract by green method.•AgNPs were successfully synthesized using bacterial supernatants at pH 10 and 60 °C.•AgNPs synthesized exhibited antimicrobial activity against E. coli.•AgNPs biosynthesized using the supernatant of C. necator at pH 10 and 60 °C presented the highest antimicrobial activity against E. coli.