While several individuals contributed to early microscopic observations, two names prominently stand out: Robert Hooke and Antonie van Leeuwenhoek.
Robert Hooke's Contributions (1665)
Robert Hooke, a Fellow of the Royal Society, was the first to describe the fruiting structures of molds in 1665 using a primitive microscope. His observations, though not of bacteria themselves, represented a crucial early step in understanding the existence of microscopic life. https://pubmed.ncbi.nlm.nih.gov/15209075/ https://www.aaas.org/taxonomy/term/10/discovery-bacteria https://royalsocietypublishing.org/doi/10.1098/rsnr.2004.0055 He documented live processes, furthering the field. https://bio.libretexts.org/Bookshelves/Microbiology/Microbiology_(Boundless)/01%3A_Introduction_to_Microbiology/1.01%3A_Introduction_to_Microbiology/1.1B%3A_History_ofMicrobiology-_Hooke_van_Leeuwenhoek_and_Cohn
Antonie van Leeuwenhoek's Breakthrough (1676)
Antonie van Leeuwenhoek, also a Fellow of the Royal Society, is largely credited with the discovery of bacteria in 1676. He meticulously documented his observations of microorganisms, including bacteria, protists, and other microscopic life forms in pond water and other samples. https://pmc.ncbi.nlm.nih.gov/articles/PMC10458164/ https://en.wikipedia.org/wiki/Antonie_van_Leeuwenhoek He provided detailed descriptions far surpassing Hooke's earlier work, becoming the first to document microscopic observations of muscle fibers and bacteria. https://asm.org/Articles/2022/June/Suddenly-I-See-How-Microscopes-Made-Microbiology-P
Conclusion
Both Hooke and van Leeuwenhoek made significant contributions to the early understanding of microorganisms. While Hooke provided early descriptions of microscopic life, van Leeuwenhoek is generally given credit for the first discovery and documentation of bacteria. The existence of microscopic organisms was established between 1665 and 1683 through their combined efforts.
