Microbiologists work in the field of bacteriology and study bacteria, environmental microbiology and study microbial processes in the environment, work in the food industry and study pathogenic microorganisms that cause foodborne illness and spoilage, work in field of biotechnology and study microorganisms that produce useful products, work in the field of mycology and study fungi, protozoology and study protists, work in the field of virology and study viruses, the role of microorganisms in health and illness.