The first observation of microbes using a microscope is generally credited to the Dutch draper and haberdasher, Antonie van Leeuwenhoek, who lived for most of his life in Delft, Holland. It has, however, been suggested that a Jesuit priest called Athanasius Kircher was the first to observe microorganisms. He was among the first to design magic lanterns for projection purposes, so he must have been well acquainted with the properties of lenses. One of his books contains a chapter in Latin, which reads in translation – ‘Concerning the wonderful structure of things in nature, investigated by Microscope. Here, he wrote “who would believe that vinegar and milk abound with an innumerable multitude of worms”. He also noted that putrid material is full of innumerable creeping animalculae. These observations antedate Robert Hooke’s Micrographia by nearly 20 years and was published some 29 years before van Leeuwenhoek saw protozoa and 37 years before he described having seen bacteria.
Reference: http://helixgene.com/microbiology_and_molecularbiology.html
Photo: http://www.campion.ox.ac.uk/sites/default/files/kircher-portrait.jpg