What contribution did Robert Koch make to bacteriology?

Robert Koch made a number of significant contributions to bacteriology and is commonly termed the father of modern bacteriology. Some of his contributions are:
1) Koch's postulates: A set of four postulates that are used as a standard for determining the exact bacterium responsible for causing an infectious disease. 
2) Causative agent for Anthrax: Koch determined bacillus anthracis to be the causative agent of the infection anthrax. He extracted the bacterium from an infected sheep and injected a mouse with it. He reported that the mouse also became infected.
3) Creation of solid medium for bacterial growth: Instead of using a liquid medium for bacterial growth, Koch started using a solid medium (by solidifying liquid broth with gelatin and agar), which is much easier to handle and work with.
4) Staining for improved visibility: Koch also developed methods to stain bacteria, which improves their visibility when using a microscope.
For his contributions, Robert Koch was awarded the Nobel Prize in 1905. 
http://broughttolife.sciencemuseum.org.uk/broughttolife/people/robertkoch