CHARACTERIZATION AND ANTIMICROBIAL ACTIVITY OF ZINC NANOPARTICLE SYNTHESIZED FROM SOIL BACTERIAL ISOLATES

Abstract

Zinc (Zn) nanoparticles have piqued the interest of researchers all over the world due to their numerous potential as antibacterial and antifungal compounds in biomedicine and agriculture. Green nanotechnology has developed as an important approach for the fabrication and production of Zn nanoparticles in recent years. Bacteria have unrivalled capability to convert zinc ions into nanoparticles, which make them the best candidate for the synthesis of Zn nanoparticles because of their rapid growth rates and ease of handling. Therefore, this study was performed to characterize and evaluate the anti-microbial activity of zinc nanoparticles synthesized from soil bacterial isolate. Three different bacteria, J-1, J-2 and J-3 were found in the soil sample. A single bacteria i-e., J-2 with isolated colonies was selected from them and subjected to further processing and later on identified as Serratia nematodiphila through biochemical tests and sequencing. The Zn nanoparticles were prepared by mixing zinc sulphate stock solution with the bacterial supernatant culture and incubated in the dark in shaking incubator for 3-5 days. After incubation, the appearance of white color precipitate indicated the successful formation of Serratia-nematodiphila mediated Zn nanoparticles. The nanoparticles were further analyzed via UV-Vis, XRD, FT-IR, SEM and TEM analysis. The nanoparticles were pure, spherical, polydispersed and crystalline in nature. The nanoparticles ranged in size from 17 nm to 28 nm with an average size of 24.74 nm. The FTIR values for the synthesized Zn nanoparticles were 510, 620, 880, 1430, 1600, 2400, 3100, 3350, 3600 and 3700 cm -1. The highest peaks formed ranged from 3100 to 3700 cm -1. Weak peak was formed at 2400 cm -1, whereas, medium peak was observed at 1430 and 1600 cm -1. The maximum SPR was found at 379 nm. The nanoparticles showed antibacterial activity and antifungal activity against S. aureus, E. coli, Sporothrix schenkii and Aspergillus fumigatus, respectively at a concentration of 100 µg/mL and 75 µg/mL, respectively. The zones of inhibitions were reduced with the decrease in nanoparticles concentrations. Hence, according to the findings of the preceding investigations the bacteria-synthesized Zn nanoparticles have a strong antibacterial and antifungal potential.

Keywords : Aspergillus fumigatus, FT-IR, Serratia-nematodiphila, Sporothrix schenkii,  Zn nanoparticles.