Dr. Alexander Flemming was an army doctor in First World War. He observed that many injured soldiers died because of bacterial infection of wounds.
He was working on antibiotics in his lab. One day he keenly observed that some fungi (mould) were preventing the growth of bacteria in the petridish, in which he was growing bacterial colonies. He separated the substances released by the fungus and tested it on some other disease causing bacteria. This substance also killed many other disease causing bacteria. The mould or fungus separated was identified as Penicillium notatum. The substance which was produced by the fungu Penicillium is named as Penicillin Substances that killed bacteria were generally named as antibiotics by D. Flemming.
The discovery of the antibiotic, penicillin was announced in 1929. In 1945 Dr. Alexander Fleming was awarded the Nobel prize along with other scientists (Dr Howard flory, and Dr. Ernst B chain) The discovery of penicillin paved the way to the discovery of many antibiotics like streptomycin, erythromycins etc. Can our body prevents the diseases without using antibiotics.