Glossary

Algae A type of phototroph that grows by oxygenic photosynthesis and whose cells contain a nucleus.  There is an astonishing variety of algae that differ in many ways, but for practical purposes they can be considered microscopic plants and are found nearly in all soils, sediments and waters where there is light.
Anoxygenic photosynthesis Photosynthesis that does not produce oxygen gas (see oxygenic photosynthesis).  For more detail, see the Photosynthesis page.
Autotroph An organism that can use carbon dioxide as the sole carbon source for growth.
Chemoautotroph An organism that uses energy from chemical reactions to grow on carbon dioxide as the sole carbon source.
Chemoautotrophy The process by which chemical energy is used to convert carbon dioxide into new cellular material. Winogradsky called this chemosynthesis.
Chemosynthesis See Chemoautotrophy
Cyanobacteria A type of phototroph that grows by oxygenic photosynthesis.  Unlike algae and diatoms, their cells do not contain a nucleus.  For practical purposes they can be considered microscopic plants and are found nearly in all soils, sediments and waters where there is light.
Diatoms A type of phototroph that grows by oxygenic photosynthesis.  Like algae, their cells have nuclei, but unlike algae their cell walls are made of silicon dioxide; i.e. glass.  These are the original organisms that live in glass houses and are found in nearly all soils, sediments and waters where there is light
Enrichment culture A method of growing specific types of microbes from the environment by providing the right environmental conditions (temperature, light, pH, etc.) and nutrients that select (enrich) for the desired type of microbe.  Winogradsky columns simultaneously enrich for multiple types of phototrophic microbes by generating multiple zones where specific type of phototrophs prefer to grow.
Green phototrophic bacteria A type of phototroph that grows by anoxygenic photosynthesis and whose cells do not contain a nucleus.  Green phototrophic bacteria can come in a range of colors from olive green to rust colored to brown.
Heterotroph An organism that can use organic carbon as the sole carbon source for growth.  Organic carbon includes carbohydrates, proteins, lipids, and organic acids like acetic acid (i.e. vinegar) and alcohols (including ethanol).
Heterotrophy The process by which organic carbon is oxidized to carbon dioxide and the energy released by this process is captured by an organism for growth.
Microbe An organism that is too small to be seen by the unaided human eye (<0.1 mm); also microorganism.
Microorganism See microbe
Oxygenic photosynthesis Photosynthesis that leads to the production of oxygen gas.  Oxygenic photosynthesis is the source of all oxygen in the earth’s atmosphere, half of which is produced by microbial phototrophs (algae, diatoms, and cyanobacteria) in the oceans. For more detail, see the Photosynthesis page.
Photoautotroph An organism that uses light energy to grow on carbon dioxide as the sole carbon source. Plants and most phototrophic microbes are photoautotrophs.
Photoautotrophy See Photosynthesis
Photosynthesis The process by which light energy is used to convert carbon dioxide into new cellular material. Also known as photoautotrophy.
Phototroph An organism that can capture light energy and use that energy to support its growth.
Purple phototrophic bacteria A type of phototroph that grows by anoxygenic photosynthesisand whose cells do not contain a nucleus.  Purple phototrophic bacteria can come in a range of colors from bright purple to blood red to brownish.
Sulfate reducing bacteria Heterotrophic or autotrophic  bacteria that reduce sulfate to hydrogen sulfide.  Sulfate serves the same purpose for these organisms that oxygen serves for human cells, so these organisms are “breathing” sulfate.
Winogradsky column A method for enriching phototrophic microbes from sediment, soil, and water samples generating opposing gradients of sulfide and oxygen in a microcosm.  Named for Sergei N. Winogradsky, a famous Russian microbiologist of the late 19th and early 20th century.

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