Nano materials and their application are of great use in research because of their size range. In this study, Auricularia polytricha (EW1) collected from Benin in Southern Nigeria was subjected to mutation by exposure to UV-light resulting in a mutant (EW1M1). EW1 and EW1M1 were evaluated for biosynthesis of silver nano-particles. The anti-microbial properties of both strains were also evaluated. Absorption spectra of silver nano-particle (AgNPs) of mutant exhibited a strong broad peak at 420 nm while wild type absorption peak was obtained at less than 420 nm. The mutant was further characterised. DLS showed a monodispersion with diverse sizes, morphology and shapes. TEM micrograph revealed a monodispersed formation of the nano-particles, with uniform size at 10 – 20 nm. FTIR study revealed the absorption bands at 3380, 2921, 2839, 1658, 1083 and 610 cmֿ1 respectively showing the functional groups reducing the silver nitrate to silver ion. There was formation of zone of inhibition on all the microorganisms that were used for the study but the control showed no zone of inhibition. The mushroom extract of mutant strain exhibited higher anti microbial activity than the wild type.