Microbiology, << `my` kroh by AHL uh jee, >> is the study of microscopic organisms. Scientists sometimes call these organisms microbes or microorganisms. They typically include bacteria, fungi, and viruses as well as single-celled organisms called archaea, animallike creatures called protozoans, and plantlike life forms called algae. Microbiologists study microorganisms to learn about basic processes common to all living things. Microbiology also addresses practical problems in agriculture, industry, medicine, and the environment.
Microorganisms
live almost everywhere on Earth. A typical microorganism measures less than 10 micrometers. A micrometer equals 1/25,400 inch or 0.001 millimeter. Microorganisms vary in size from less than 0.1 micrometers (0.0001 millimeter) to many hundreds of micrometers. Scientists study most microorganisms with microscopes that magnify objects at least 1,000 times. To study viruses, microbiologists must use electron microscopes that magnify objects many thousands of times.
Scientists call viruses acellular microorganisms because they do not have true cell structures. All other microorganisms are cellular. They have cell membranes containing a liquid called cytoplasm and either a nucleus or a nucleoid that carries genetic material. Bacteria are the smallest single-celled organisms. The smallest bacteria may measure as little as 0.2 micrometer (0.0002 millimeter). About 1,000 small viruses could fit into a cell the size of one of these bacteria.
Because many microorganisms grow rapidly, they serve as excellent models for studying basic life processes. Studies of microorganisms help scientists to understand the functioning of cells in larger organisms, including people. Scientists have studied microorganisms heavily since their discovery in the late 1600’s. However, some scientists estimate that as few as 1 percent of Earth’s microorganisms have been studied.
Fields of microbiology.
Microbiology consists of a broad area of study that includes numerous specialized fields. General microbiologists study the basic features of microorganisms, such as their ecology, physiology (functioning), and structure. Many microbiologists specialize in the study of certain kinds of microorganisms. For example, bacteriologists work with bacteria, mycologists examine fungi, and virologists study viruses.
Many microbiologists study the relationships between microorganisms and plants and animals, including people. For example, agricultural microbiologists study the effects of microorganisms on soil fertility and plant diseases. Medical and veterinary microbiologists investigate microorganisms involved in human and animal diseases. Dental microbiologists study the microorganisms found in the mouth and their role in tooth decay. Industrial microbiologists use microorganisms to manufacture such products as alcoholic beverages, antibiotics, and dairy products.
Tooth decay
