Basic Microbiology Glossary

   Aerobic using oxygen for metabolism.

Anaerobic not using oxygen for metabolism. Some anaerobes cannot survive

in the presence of oxygen.

Agar plate a medium made solid by the addition of agar, a seaweed derivative.

The medium contains specific nutrients for culturing specific microbes

. Aplate is most often prepared in a petri dish.

Archaea a domain of life believed to be the most ancient and to contain

organisms believed to be similar to ancient prokaryotes. This domain of

unicellular organisms includes the halophiles, organisms that grow in high-salt

environments; methanogans, anaerobes that produce methane; and

thermophiles, which thrive in high-temperature environments.

Bacteriorhodopsin a red pigment that enables some microbes to turn solar

energy into chemical energy.

Binary fission splitting of a parent cell into two daughter cells.

Carotenoids a group of pigments ranging from yellow to red that occur widely

among a variety of organisms. They help protect Halobacterium from the

harmful effects of UV radiation.

Clone a genetic duplicate of an organism. A microbial colony consists of

clones of the founding cell.

Colony a visible cluster of millions of microbial cells resulting from binary

fission of a founder cell and its daughters and so on.

Colony-forming unit (cfu) a microbial cell capable of undergoing binary

fission and founding a colony.

Generation time length of time for a particular microbe to complete its

division cycle to form two new daughter cells.

Genotype the genetic makeup of an organism, either in total or in terms of

one or a few sets of alleles.

Incubate to furnish appropriate conditions for an inoculated solid or liquid

medium to produce colonies or larger populations of the inoculated microbes.

Inoculum living material used to initiate a culture of microbes

Insertion sequences (IS elements) sections of DNA that insert at random

into the genome, causing mutations that often bring about phenotypic change;

also known as “jumping genes.”

Lyse to cause the breaking open of a cell wall and membrane such that the

contents are released and the cell dies (the breaking open itself is referred to

as “lysing”).

Medium substrate or material on or in which microbes are grown for study.

Microbiology the study of single-celled life forms.

Pathogen a disease-causing agent.

Phenotype observable characteristic of an organism, e.g., brown, blue, or

green eyes in people.

Pure culture colony or collection of microorganisms containing only one

type. A pure culture is usually obtained after a series of cultures has been

performed to isolate a particular microbe.

Salinity measure of the proportion of salt in a substance. Aquatic halophiles

live in water of high salinity.

Solar salt production collection of sea salt by means of flooding shallow pools

and allowing the sun to evaporate the water. The brine is moved to pools of

successively higher salt concentration until crystals form.

Sterile technique (aseptic technique) accepted laboratory practices geared

toward preventing contamination of cultures and the laboratory and

surroundings. Sterile technique covers procedures regarding lab preparation,

transfer of cultures, and cleanup and disposal.

Streak to spread a microbial sample over the surface of a plate in order to

isolate colonies. Usually, streaking is done as a pattern of zigzags.