People fermented food for millennia without a theory of microbes. The microscope made the actors visible; germ theory made them politically urgent.
The twentieth century added chemistry (antibiotics) and information (sequencing). Each gift created a new problem: resistance, and too much data.
Timeline
Antonie van Leeuwenhoek describes moving specks from teeth and water.
Swan-neck flasks and pasteurisation attack spontaneous generation and save food.
A specific bacillus is tied to a specific disease ? germ theory gets a method.
Hans Christian Gram gives clinics a two-bucket wall test still used daily.
Fleming sees a mould zone; Florey and Chain later make a medicine.
Soil microbe chemistry hits tuberculosis ? a reminder that allies live in dirt.
rRNA trees peel Archaea away from 'bacteria' as a mixed bag.
Haemophilus influenzae is sequenced; metagenomics will soon skip culture entirely.
History of bacteria is also history of cities, war hospitals and kitchens ? not only famous men with microscopes.
Keep exploring
More in Tree of microbes
Viruses
Packets of DNA or RNA that are not cells — they replicate only inside living hosts.
Familiarity 96Fungi
A eukaryotic kingdom of yeasts, moulds and mushrooms — chitin walls, external digestion, partners of plants.
Familiarity 80Archaea
A prokaryotic domain that is not bacteria — methanogens, extremophiles and no known human pathogens.
Familiarity 35Bacteriophages
Viruses that infect bacteria — Earth's most abundant biological entities, and a concept-level idea in medicine.
Familiarity 42Protozoa
Motile unicellular eukaryotes — a teaching grade that includes pond ciliates and a minority of serious parasites.
Familiarity 58