Alexander flemming is really great!!!He made many efforts to help the soldiers who were injured during first world war by discovering penicillin .This ia antibiotic which helps to kill bacteria. He discovered penicillin which was named after identifying the organism as penicillium notatum.Alexander flemming helped all people to get cured from bacterial problems. He is obviously great and appreciable for his work if discovery. We all are really thankful to him . Hope this helps you