The University of Wisconsin-Madison is world-renowned for its research and training in microbiology. Two closely interacting and complementary departments serve as a core of microbiological research on the campus, Bacteriology and Medical Microbiology and Immunology. These two departments have unified their respective graduate programs to form an integrated Microbiology Doctoral Training Program, including all faculty and trainers previously affiliated with either or both departments, as well as trainers from other departments on campus.

The UW-Madison played a central role in the growth of Microbiology. Six UW faculty have served as president of the American Society of Microbiology (or its forerunner). Joshua Lederberg, then a member of the Genetics Department, received the Nobel Prize for establishing that genetic exchange occurs in bacteria. Edward L. Tatum received early training at the UW and developed the one gene-one enzyme hypothesis, for which he shared the Nobel Prize. Nitrogen-fixation by microorganisms associated with plants has been investigated with great insight for more than 50 years by members of the departments of Bacteriology and Biochemistry. The Primary penicillin-producing strains of Penicillium were developed in collaboration with scientists in the departments of Bacteriology and Botany. Today's faculty continue to develop novel antimicrobial natural products. Research in sensory behavior of microorganisms is a current strength of this campus and follows upon the pioneering genetic and biochemical studies of chemotaxis by Julius Adler (Biochemistry).

Much of the birth and development of molecular biology also occured at the UW. Gobind Khorana shared the Nobel Prize for deciphering the genetic code and was the first to synthesize a gene with a member of the Biochemistry faculty. Members of the department of Genetics, Biochemistry, and Zoology provided many of the earliest insights into the mechanism of protein synthesis, ribosome structure and assembly. Members of our faculty continue this line by investigating the origin of the genetic code, the structure and function of transfer RNA and the mechanisms controlling synthesis of ribosomal RNA. Several faculty in the departments of Bacteriology, Biochemistry, Genetics, and Oncology played and continue to have central roles in the analysis of gene regulation, DNA replication, and transposition, using Escherichia coli, other bacteria, and bacteriophages lambda or mu. Howard Temin (Oncology) received the Nobel Prize for discovering reverse transcription by oncogenic RNA viruses, now known as retroviruses. The laboratory of Fred Blattner in Genetics completed the nucleotide sequencing of the chromosome of the bacerium E. coli, a crucial contribution to the current widespread efforts to elucidate microbial and other complete genomes.

In addition to studies of model microorganisms, UW investigators have made significant contributions to the study of pathogenic microorganisms and of immunologic responses of the mammalian host. Examination of the numerous increasingly important etiologic agents of infectious diseases include research on basic cellular and molecular biology, such as protein processing and export; on molecular mechanisms of pathogenesis, such as adherence and entry, toxin production and gene regulation during infection; and on critical host defense mechanisms, such as macrophage activation, cytokine production, and lymphocyte-mediated immunity. There are many bacteriologists, virologists, parasitologists, mycologists, and immunologists on campus participating in these areas, and members of the Departments of Bacteriology and Medical Microbiology and Immunology are actively involved with programs in Cell and Molecular Biology, Virology, and Cell and Molecular Parasitology.