Synthesis of silver nanoparticles by solar irradiation of cell-free Bacillus amyloliquefaciens extracts and AgNO3

► AgNPs can be synthesized by the biomass of Bacillus amyloliquefaciens under solar radiation. ► The synthesis rate is much higher than previous safe microbial synthesis methods. ► Application of sunlight overcomes the energy consumption for preparation of AgNPs. ► AgNPs show obvious antimicrobial activity against Bacillus subtilis and Escherichia coli.