Koch was born on December 11, 1843. As one of thirteen children born to a mining engineer and his wife, Koch spent his youth in the Harz Mountains in Clausthal, Germany. During his adolescent years, his father insisted he learn the shoemaker's trade, but when money became available for an academic career, Koch entered the University of Göttingen as a student of medicine and natural science at the age of 19. He graduated in 1866. After service as a surgeon in the Franco-Prussian War, Koch settled down as a country doctor in Wollstein, what is now Wolsztyn, Poland.

Working in a homemade laboratory that was separated from his examining room by a curtain, Koch began to study microorganisms. His microscopic studies led him to develop a technique by which he spread a liquid gelatin on glass slide plates to produce a transparent solid medium for the isolation of pure cultures...