The answer is Antibiotic. This revolutionized medicine, However the effectiveness and easy access lead to the over use of this substance. The substance produce by microorganism that can kill or inhibit the growth of others are being studied to produce a synthetic form that can be use in medicine. Penicillin is an example of antibiotic that was derived from fungi and can kill bacterias. There is now a serious threat about antimicrobial resistance. This can also be used in soaps and disinfectants.
