Bacteriologists are the professionals trained in bacteriology which is a subdivision of microbiology. They examine the growth, structure, development, and other characteristics of bacteria in order to promote health and disease diagnosis and prevention. The beginnings of bacteriology corresponded with the development of the microscope, and the 17th century Dutch naturalist Antonie van Leeuwenhoek is believed to be the first person to see micro-organisms, including bacteria. The 19th century German physician Robert Koch was one of the founders of bacteriology. Another German, the naturalist and botanist Ferdinand Julius Cohn who became known for his studies of algae, bacteria, and fungi, is also considered a founder of bacteriology. He published many of the founding papers of bacteriology in the journal ‘Contributions to the Biology of Plants.’ Taking forward the work on bacteriology, Louis Pasteur established the connections between bacteria and the processes of fermentation and disease, and succeeded in immunizing animals against two diseases caused by bacteria. The Scottish biologist Sir Alexander Fleming was also a major authority in the field of bacteriology. This section provides you information about the life and works of famous bacteriologists from all over the globe.