[01] Parthasarathy Ramalingmam, Department of Plant Science, School of Life Sciences, Bharathidasan University, Tiruchirappalli, TamilNadu, India. [02] Sathiyabama Muthukrishnan, Department of Plant Science, School of Life Sciences, Bharathidasan University, Tiruchirappalli, TamilNadu, India. [03] Prabha Thangaraj, Department of Plant Science, School of Life Sciences, Bharathidasan University, Tiruchirappalli, TamilNadu, India.

The development of reliable green process for the synthesis of silver nanoparticles is an important branch of Nanobiotechnology. In the present investigation the use of the endophytic fungus Curvularialunata for the extracellular biosynthesis of silver nanoparticles (AgNPs) from silver nitrate solution is reported. It was observed that the aqueous silver (Ag⁺) ions, when exposed to a filtrate of C. lunata, were reduced in solution, resulting in the formation of stable AgNPs. These AgNPs were characterized by means of several techniques. The nanoparticles show maximum absorbance at 422 nm on ultraviolet-visible spectra. The presence of protein was identified by Fourier Transform infrared spectroscopy. The reduction of Ag⁺ ion to elemental silver was characterized by Energy - dispersive X-ray (EDX) Spectroscopy. Scanningelectron micrograph revealed the formation of polydispersed nanoparticles of 10-50 nm. The nanoparticles were also evaluated for their enhanced antimicrobial activities with various antibiotics against gram positive and gram negative bacteria. The antibacterial activities of Ampicillin, Rifampicin, Chloramphenicol, Erythromycin, and Kanamycin were increased in the presence of AgNPs against test strain. The highest fold increase of area was found for Erythromycin and Carbenicilin against E. coli, Ampicilin against S. paratyphi, Erythromycin against B. subtillis. The results showed that the combination of antibiotics with AgNPshas better antimicrobial effects.

Endophytic Fungi, Silver Nanoparticles, SEM, FTIR, Antibacterial Activity

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