Aerobe. Organisms that require oxygen for survival. Bacterial aerobes use oxygen as the terminal electron
acceptor during respiration.
Aerotolerant anaerobes. Organisms that cannot use oxygen, nor are affected by its presence.
Anaerobes. Organisms that do not require oxygen for survival. These organisms use inorganic compounds
as the terminal electron acceptor during respiration.
Complex medium. An undefined medium containing unknown quantities of reagents. These media contain
complex ingredients, such as yeast extract and peptone, which contain a combination of compounds in
Cryopreservation. Ultra-low temperature storage of cells, tissues, embryos, or seeds. This storage is usually
carried out using temperatures below -100°C.
Defibrinated blood. Whole blood from which fibrin has been separated during the clotting process.
Defined medium. Media with known proportions of all reagents. These media consist of a defined carbon
and nitrogen source.
Desiccant. A hygroscopic substance that induces or sustains a state of dryness in its local vicinity in a sealed
Desorption. The phenomenon where a substance is released from or through a surface.
Enrichment medium. These media contain the nutrients required to support the growth of a wide array
Facultative anaerobe. An organism that can survive in the presence and absence of oxygen. If given the
choice, these organisms prefer the use of oxygen as it has the highest reduction potential of all terminal
Fastidious. Having to do with microorganisms that have complex nutritional needs and require growth on
Hypotonic. An environment where the water concentration is greater and solute concentration is lower on
the outside of a cell. In this environment, water flows into the cell.
Isotonic. An environment where both the water and solute concentrations are the same on the inside and
outside of a cell. In this environment, water flows in and out of a cell at an equal rate.
Lyophilization. A process that extracts water molecules from microbial cultures so that products remain
stable and easy to store. This storage is usually carried out under low-oxygen, low-moisture conditions at
Mesophile. An organism that grows best at moderate temperatures, between 25°C to 40°C.
Microaerophile. An organism that requires oxygen for respiration, however, in lower levels than found in
Obligate anaerobe. An organism that cannot survive and are often killed by the presence of oxygen.
Osmolarity. The concentration of a solution in terms of osmoles. Osmosis is the diffusion of water across
a membrane from an area of higher water concentration (lower solute concentration) to lower water
concentration (higher solute concentration).
Psychrophile. An extremophilic organism that is capable of growth in cold temperatures ranging from 0°C
Ribotyping. A method of identification involving the fingerprinting of genomic DNA restriction fragments.
Selective medium. Media used for the growth of specific microorganisms. These media are often
supplemented with reagents, such as antibiotics, that prevent the growth of other microorganisms.
Thermophile. An extremophilic organism that thrives a high temperatures ranging from 45°C to 122°C.