Robert Koch Identifies Tuberculosis Bacillus

Robert Koch presented his identification of Mycobacterium tuberculosis to the Berlin Physiological Society, demonstrating through systematic experimentation that a specific bacterium caused tuberculosis. Working alone for nearly six months, Koch developed staining techniques using methylene blue and Bismarck brown to visualize the slow-growing bacillus, then cultured it on coagulated blood serum. He fulfilled what became known as Koch's postulates by isolating the organism, growing it in pure culture, and reproducing the disease in animal subjects.