Question: what are the major branches of microbiology?
Answer: Bacteriology: the study of bacteria.
Immunology: the study of the immune system. ... 
Mycology: the study of fungi, such as yeasts and molds.
Nematology: the study of nematodes (roundworms).
Parasitology: the study of parasites. ... 
Phycology: the study of algae.