Bacteriologists are scientists who study bacteria, which are a type of prokaryotic microorganisms. Bacteria are found in all environments on Earth, from soil to water to air, and they play important roles in the cycling of nutrients and the decomposition of organic matter. Bacteriologists study the structure, function, and genetics of bacteria, as well as their interactions with other organisms. They also study the mechanisms by which bacteria cause disease and the development of antibiotics and other antimicrobial agents to treat bacterial infections. Bacteriology is a branch of microbiology and is closely related to the fields of molecular biology, cell biology, and immunology.