phototroph

Examples of phototroph in the following topics:

• Photoautotrophs and Photoheterotrophs

  • Phototrophs are organisms that use light as their source of energy to produce ATP and carry out various cellular processes.
  • Not all phototrophs are photosynthetic but they all constitute a food source for heterotrophic organisms.
  • Phototrophs can be of two types based on their metabolism .
  • In terrestrial environments plants are the predominant variety, while aquatic environments include a range of phototrophic organisms such as algae, protists, and bacteria.
  • Most of the well-recognized phototrophs are autotrophs, also known as photoautotrophs, and can fix carbon.

• Anoxygenic Photosynthesis

  • Anoxygenic photosynthesis is the phototrophic process where light energy is captured and converted to ATP, without the production of oxygen.
  • There are several groups of bacteria that undergo anoxygenic photosynthesis: Green sulfur bacteria , green and red filamentous anoxygenic phototrophs (FAPs), phototrophic purple bacteria, phototrophic Acidobacteria, and phototrophic heliobacteria.
  • Anoxygenic phototrophs have photosynthetic pigments called bacteriochlorophylls (similar to chlorophyll found in eukaryotes).
  • Bacteriochlorophylls c-g have the corresponding "peak" absorbance at more blue wavelengths when dissolved in an organic solvent, but are similarly red-shifted within their natural environment (with the exception of bacteriochlorophyll f, which has not been naturally observed).Unlike oxygenic phototrophs, anoxygenic photosynthesis only functions using (by phylum) either one of two possible types of photosystem.

• Facultative Phototrophy

  • A facultative phototroph can rely on photosynthesis and alternative energy sources to survive and grow.
  • Phototrophs, a type of autotroph, convert physical energy from sunlight (in case of green plants) into chemical energy in the form of reduced carbon.
  • 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.

• Anoxygenic Photosynthetic Bacteria

  • Anoxygenic photosynthesis is the phototrophic process where light energy is captured and converted to ATP, without the production of oxygen; water is, therefore, not used as an electron donor.
  • There are several groups of bacteria that undergo anoxygenic photosynthesis: green sulfur bacteria, green and red filamentous anoxygenic phototrophs (FAPs), phototrophic purple bacteria, phototrophic acidobacteria, and phototrophic heliobacteria.
  • Anoxygenic phototrophs have photosynthetic pigments called bacteriochlorophylls ; these are similar to chlorophyll found in eukaryotes.
  • Unlike oxygenic phototrophs, anoxygenic photosynthesis only functions using either one of two possible types of photosystem.
  • Bacteriochlorophylls are photosynthetic pigments that occur in various phototrophic bacteria.

• Chloroflexus and Relatives

  • Chloroflexus are Gram-negative filamentous anoxygenic phototrophic organisms that utilize type II photosynthetic reaction centers.
  • As a genus, Chloroflexus spp. are Gram-negative filamentous anoxygenic phototrophic (FAP) organisms that utilize type II photosynthetic reaction centers containing bacteriochlorophyll a similar to the purple bacteria, and light-harvesting chlorosomes containing bacteriochlorophyll c similar to green sulfur bacteria of the Chlorobi.
  • As the name implies, these anoxygenic phototrophs do not produce oxygen as a byproduct of photosynthesis, in contrast to oxygenic phototrophs such as cyanobacteria, algae, and higher plants.
  • While oxygenic phototrophs use water as an electron donor for phototrophy, Chloroflexus uses reduced sulfur compounds such as hydrogen sulfide, thiosulfate, or elemental sulfur.
  • The Chloroflexi or Chlorobacteria are a phylum of bacteria containing isolates with a diversity of phenotypes including members that are aerobic thermophiles, which use oxygen and grow well in high temperatures, anoxygenic phototrophs, which use light for photosynthesis, and anaerobic halorespirers, which use halogenated organics (such as the toxic chlorinated ethenes and polychlorinated biphenyls) as energy sources.

• Alphaproteobacteria

  • The Alphaproteobacteria comprise most phototrophic genera, but also several genera metabolising C1-compounds (e.g., Methylobacterium spp.), symbionts of plants (e.g., Rhizobium spp.) and animals, and a group of pathogens, the Rickettsiaceae.
  • Aerobic anoxygenic phototrophic bacteria are alphaproteobacteria, widely distributed marine plankton that may constitute over 10% of the open ocean microbial community.

• Betaproteobacteria

  • ., the ammonia-oxidising genus Nitrosomonas) and some phototrophs (members of the genera Rhodocyclus and Rubrivivax).

• The Energetics of Chemolithotrophy

  • The chemotroph designation is in contrast to phototrophs, which utilize solar energy.

• Electron Donors and Acceptors

  • Organotrophs (animals, fungi, protists) and phototrophs (plants and algae) constitute the vast majority of all familiar life forms.
  • Because of their volume of distribution, lithotrophs may actually out number organotrophs and phototrophs in our biosphere.

• Habitats and Energy Metabolism of Crenarchaeota

  • Other groups of archaea use sunlight as a source of energy (phototrophs).
  • Phototrophic archaea use light to produce chemical energy in the form of ATP.