The study of microorganism is called microbiology, which includes bacteria, viruses, fungi and Protozoa. Microbes play a major role in this field. Microbes are also used for life-saving drugs etc.. The effect of ultraviolet rays on the bacterias are mostly lethal to them, UV is a minor fraction of the solar spectrum reaching the ground surfaces, the UV light radiation will reduce the microbes in the surroundings as well as in the labs. Aim: The aim of this study was to evaluate the effect of

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... ultraviolet rays on pathogenic bacterias. Materials and methods: Three organisms were selected for the study. Pseudomonas, S. Aureus and Enterococcus. 30 watts Uv tube was used to evaluate the antibacterial activity of the Uv radiation. The exposure time was determined as 5, 10 and 15 mins at a close distance of 10cm. 20 microliter of suspension was taken and mixed in 2 ml of sterile normal saline and exposed for respective duration. Sub culture was done on suitable media after the exposure . Time exposed plates were incubated at 37 degree Celsius overnight and checked for the total CFU and data were tabulated. Results: The Ultraviolet radiation of pathogenic bacteria resulted in a significant reduction of the total colony forming unit. Conclusion: Ultraviolet rays were lethal to the bacterias. There are many airborne bacterias surrounded by environment ultraviolet rays exposure will cause an apparent decrease in the pathogenic bacterias.