acidophile – acid-loving microbe

alkaliphile – alkaline-loving microbe

Archaea – A group of microbes that look like bacteria, but are no more related to Bacteria than to Eukarya.

Bacteria – The group of microbes that, like archaea, do not have their DNA contained in a nucleus and do not have compartments inside their cells.

endosymbiont – any organism that lives within the body or cells of another organism in a mutualistic relationship with the host body or cell, often but not always to mutual benefit.

Eukarya – Also called eukaryotes. A group of organisms, some of which are microbes, that have cells with compartments (chloroplasts, mitochondria, for example) and with their DNA contained a compartment called a nucleus. Plants, animals, fungi and humans are eukaryotes as are the microbes yeast and algae.

extremophile – a microbe that loves “extreme” conditions; “extreme” is based on what is extreme to humans, since we are making the definition; usually this refers to organisms (nearly all of which are microbes) that live at the very extremes of conditions

halophile – salt-loving microbe

horizontal gene transfer – The transfer of genes (made of DNA) between cells (usually belonging to unrelated groups). Genes encoding traits are usually transfered from ”parents” to their progeny and this is called vertical transmission. When traits are transferred to unrelated organisms by transfering DNA, this is called horizontal transfer or acquisition. This process largely happens among microbes, though there is evidence that it has happened in plants and animals.

mutualistic – an ecological association between two or more species where each species benefits.

protozoa – an informal term for single-celled eukaryotes, either free-living or parasitic, which feed on organic matter such as other microorganisms or organic tissues and debris. Historically, the protozoa were regarded as “one-celled animals”, because they often possess animal-like behaviors, such as motility and predation, and lack a cell wall, as found in plants and many algae.

psychrophile – cold-loving microbe

thermophile – heat-loving microbe; Groups of microbes are said to be “moderate thermophiles” if they grow best at 45-55°C, “thermophiles” at 55-70°C, “extreme thermophiles at 70-90°C, and “hyperthermophiles” above 90°C.

symbiosis – any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or parasitic. The organisms, each termed a symbiont, may be of the same or of different species.

xerophile – dry-loving microbe