facultative

Examples of facultative in the following topics:

• Facultative Phototrophy

  • A facultative phototroph can rely on photosynthesis and alternative energy sources to survive and grow.
  • In terms of biology facultative means "optional" or "discretionary" the antonym of which is obligate meaning "by necessity".
  • Thus facultative phototrophy means an organism that can switch between phototrophy to make organix compounds and other means of getting cellular energy.
  • Probably the best studied example of a facultative phototrophy is Chlamydomonas reinhardtii.
  • As one can imagine switching energy sources under varying conditions allows facultative microbes to live in different conditions, in the case of a facultative phototroph it can rely of light other energy sources.

• Oxygen

  • Facultative anaerobes can use oxygen, but also have anaerobic (i.e. not requiring oxygen) methods of energy production.
  • And finally, facultative anaerobes, which can grow without oxygen but can utilize oxygen if it is present.
  • Aerobically different bacteria behave differently when grown in liquid culture: 1) Obligate aerobic bacteria gather at the top of the test tube in order to absorb maximal amount of oxygen. 2) Obligate anaerobic bacteria gather at the bottom to avoid oxygen. 3) Facultative bacteria gather mostly at the top, since aerobic respiration is advantageous (ie, energetically favorable); but as lack of oxygen does not hurt them, they can be found all along the test tube. 4) Microaerophiles gather at the upper part of the test tube but not at the top.

• Hyperthermophiles from Terrestrial Volcanic Habitats

  • Thermophiles are classified into obligate and facultative thermophiles; obligate thermophiles (also called extreme thermophiles) require such high temperatures for growth, whereas facultative thermophiles (also called moderate thermophiles) can thrive at high temperatures, but also at lower temperatures (below 50°C).

• Hyperthermophiles from Submarine Volcanic Habitats

  • Thermophiles are classified into obligate and facultative thermophiles: Obligate thermophiles (also called extreme thermophiles) require such high temperatures for growth, whereas facultative thermophiles (also called moderate thermophiles) can thrive at high temperatures, but also at lower temperatures (below 50°C).

• Bacterial Genomes

  • Facultative and recently evolved pathogenic bacteria exhibit a smaller genome size than free-living bacteria, yet they have more pseudogenes than any other form of bacteria.
  • Evidence of a deletional bias is present in the respective genome sizes of free-living bacteria, facultative and recently derived parasites and obligate parasites and symbionts.
  • As such, in recently formed and facultative parasites, there is an accumulation of pseudogenes and transposable elements due to a lack of selective pressure against deletions.

• Overview of Proteobacteria

  • Most members are facultatively or obligately anaerobic, chemoautotrophs, and heterotrophic, but there are numerous exceptions.

• Noncholera Vibrios

  • Vibrio species are facultative anaerobes that test positive for oxidase and do not form spores.

• The Rumen and Ruminant Animals

  • There is no oxygen in the rumen, so bacteria in the rumen are typically anaerobes or facultative anaerobes.

• Brucellosis (Undulant Fever)

  • They function as facultative intracellular parasites causing chronic disease, which usually persists for life.

• Gas Requirements

  • They live in habitats low in oxygen, such as soils and decaying vegetable matter. 2) Facultative anaerobes that can grow either with or without oxygen, but they only fix nitrogen anaerobically.