Antimicrobial screening of silver nanoparticles synthesized by marine cyanobacterium Phormidium formosum

Nanoparticles are widely used in various fields such as electronics, cosmetics, water purification, biomedical and biotechnology. Biosynthesis of nanoparticles using biological agents have gained much attention in the area of nanotechnology in the last few decades because of cost effective, non-toxic, and eco-friendly. Algae have been used to reduce metal ions and subsequently for the biosynthesis of nanoparticles.

Silver nanoparticles (AgNPs) have been biosynthesized by Phormidium formosum isolated from Mediterranean Sea coast Egypt in an aqueous system. An aqueous solution of silver ions was treated with alive biomass of P. formousm for the formation of AgNPs. The physio-chemical properties of synthesized silver nanoparticles were studied using analytical techniques such as UV-Vis spectrophotometer, transmission electron microscopy (TEM), and Fourier Transform Infrared Spectroscopy (FTIR). The antimicrobial effect of synthesized silver nanoparticles was also tested on several microorganisms by measuring the inhibition zone.

These nanoparticles showed an absorption peak at λmax 437 nm in the UV-visible spectrum, corresponding to the Surface Plasmon Resonance of AgNPs. The transmission electron micrographs of nanoparticles in an aqueous solution showed production of silver nanoparticles synthesized by P. formosum. The obtained AgNPs are spherical in shape with a size ranging from 1.83 nm to 26.15nm. The Fourier transmittance infrared spectrum (FTIR) confirms the presence of bio component in alive biomass of P. formosum which was responsible for the nanoparticles synthesis. The antimicrobial test revealed that AgNPs synthesized by P. formosum is capable to inhibit the growth of microorganisms.

The results confirmed that AgNPs can act as a powerful antimicrobial agent against fish and human pathogens.