Biogenic Synthesis and Characterization of Silver Nanoparticles (AgNPs) Produced by Indigenous Microorganisms Isolated from Banana (Musa spp) Soils

This research focused on the screening of indigenous microorganisms isolated from banana soils for their capability to synthesize silver nanoparticles (AgNPs) extracellularly. Ninety-five isolates were screened for AgNP production. The cell-free extracts of these isolates were added to silver nitrate (AgNO3) aqueous solution and were observed for color changes from original pale yellow to dark brown. Ten isolates (3 bacteria and 7 fungi) were found capable of producing AgNPs. Bacterial isolates B2, B3, and B5 were molecularly identified as Bacillus aryabhattai, Priestia megaterium, and B. megaterium, respectively. The AgNPs produced by these bacterial isolates were circular and showed an absorbance peak at approximately 420 nm. On the other hand, the fungal isolates F2, F3, and F43 were molecularly identified as Penicilliumcitrinum, P. glaucoroseum, and P. oxalicum. The AgNPs produced by the Penicillium spp were aggregated, circular and showed absorbance peaks at 420 nm. The other four fungal isolates, F7, F24, F29, and F40, were identified as Aspergillus flavus, A. terreus, and A. japonicum (F29 and F40), respectively. The AgNPs produced by the Aspergillus spp. were circular and showed absorbance peaks between 420 nm and 450 nm. The continuous search for novel isolates that can carry out the biogenic synthesis of AgNPs remains the focus of nanotechnological research. This study confirms microorganisms of Bacillus, Penicillium, and Aspergillus genera can effectively biosynthesize AgNPs.