Microbiology as we know it today was only made possible when in the year 1674 Antonie Van Leeuwenhoek, a Dutch scientist, created the first microscope. He used a small device (microscope) that he had invented to observe small beings in soil, river-water, saliva and feces samples, which he named "animalcules". That same year Leeuwenhoek wrote several letters to the Royal Society in London describing the beings he saw through his small microscope. It was these letters that were the birth of microbiology; after all, it was these letters that opened the eyes of the Royal Society to become aware of the existence of small microscopic beings.
Read the rest of this interesting article by Ingrid da Silva Dias at: http://www.microbiologia.ufrj.br/portal/index.php/en/destaques-2/news-about-microbiology/385-the-story-of-the-emergence-of-microbiology-remarkable-facts