A microbiologist studies living organisms that are invisible to the naked eye. Microbiologists study bacteria, fungi, and other one-celled organisms (microbes), as well as viruses. A microbiologist may study a single molecule isolated from a bacterium, or a complex ecosystem with many microbial species.

In the course of their work, microbiologists do a variety of tasks. These include inoculating microbes using sterile techniques, viewing microbes under the microscope, purifying DNA or other molecules from microbes, counting microbes, preparing sterile media, and developing experiments to better understand these organisms, often using the techniques of genetic analysis. Many microbiologists supervise other employees, and they frequently work with a group of people to plan experiments or validate laboratory procedures. Some microbiologists teach or are engaged in sales, so their duties may include presenting information. As they gain experience, microbiologists working in a laboratory frequently assume more responsibility to supervise others and...