What is Anoxygenic Photosynthesis? How Does Anoxygenic Photosynthesis Work

Anoxygenic photosynthesis is a phototrophic process that captures and converts light energy to ATP without producing oxygen; water is thus not required as an electron donor.

Anoxygenic photosynthesis is a kind of anaerobic bacterial photosynthesis that uses the photosynthetic electron transport chain in a non–cyclic mode and reduced inorganic electron donors such as hydrogen sulfide, hydrogen, or ferrous ion as electron donors.

How Does Anoxygenic Photosynthesis Work

There are numerous cases of anaerobic photosynthetic electron transport chains functioning cyclically; in this circumstance, decreasing power generation is not required or is disconnected from the photosynthetic process. Green bacteria have archetypal non–cyclic anoxygenic photosynthesis.

The reductant utilized (e.g., hydrogen sulfide instead of water) and the byproduct formed distinguish bacterial anoxygenic photosynthesis from the more well-known oxygenic photosynthesis in plants (e.g. elemental sulfur instead of molecular oxygen).

Anaerobic photosynthetic pigments are similar to chlorophyll but differ in molecular detail and peak wavelength of light absorbed.

Within their typical membrane environment, bacteriochlorophylls absorb the most electromagnetic radiation in the near-infrared.

This is in contrast to chlorophyll a, the most common plant and cyanobacteria pigment, which has a peak absorption wavelength that is roughly 100 nanometers shorter (in the red portion of the visible spectrum).

Green sulfur bacteria (GSB), red and green filamentous phototrophs, purple bacteria, acidobacteria, and heliobacteria are among the bacteria that can perform anoxygenic photosynthesis.

Some archaea use light energy to power their metabolism and are thus phototrophic, although none are known to “fix” carbon (i.e.be photosynthetic).

Instead of a chlorophyll-type receptor and an electron transport chain, proteins like halorhodopsin use diterpenes to transfer ions against a gradient and create ATP via chemiosmosis in the same way as mitochondria do.

What does Anoxygenic photosynthesis produce?

Anoxygenic photosynthesis generates cellular energy (ATP) without the use of oxygen as a byproduct. Anoxygenic organisms, in contrast to eukaryotic species, rely on bacteriochlorophylls for photosynthesis.

What is the difference between oxygenic and anoxygenic photosynthesis?

Anoxygenic and oxygenic photosynthesis differ in the type of light-sensitive pigment and the process by which electrons are transferred.

Anoxygenic photosynthesis uses bacteriochlorophylls, which are red-pigmented, high-wavelength light absorbers and act as antennae that absorb light at or near the visible wavelength range.

Can anoxygenic photosynthesis be used in biosynthesis?

Anoxygenic photosynthesis is used by some bacteria but not biosynthetically. It is a process that can be highly energized but not required for the basic tasks of a bacterium, such as protection from the environment or metabolic production.

Green sulfur bacteria (GSB) use this type of cell to store energy in the form of reduced ferrous ions in their cytoplasm (ferric sulfide).

Where does Anoxygenic photosynthesis occur?

Anoxygenic photosynthesis is widely distributed over several bacterial phyla. Purple bacteria in the phylum Proteobacteria and green sulfur bacteria in the phylum Chlorobi described above inhabit various environments such as soil, ocean, lakes, and rivers.

Where do anoxygenic photosynthetic bacteria live?

Anoxygenic photosynthesis is found in some bacteria, such as the ubiquitous “Acidianus”.

The ability to perform anoxygenic photosynthesis is abundant on Earth and it’s thought to be closely related to the environment in which they live. For example, anoxygenic photosynthetic bacteria are commonly found at hot springs and petroleum deposits.

Why is bacterial photosynthesis called anoxygenic?

In contrast to oxygenic photosynthesis, which uses molecular oxygen as a primary electron donor, anoxygenic photosynthesis does not use molecular oxygen.

The name derives from the fact that “oxygen” is the correct term for molecular oxygen, whereas “anion” is used in chemistry to refer to anions with negatively charged electrons (the opposite of cation).

In contrast to other forms of bacterial photosynthesis that generate ATP as a byproduct of its energy production process.

Is anoxygenic photosynthesis?

Anoxygenic photosynthesis is one of many different types of bacterial photosynthesis.

This type of photosynthetic process has been observed in several forms and is widely distributed across several traits and phyla.

Is anoxygenic photosynthesis widely used as a part of bacterial metabolism?

Anoxygenic photosynthesis is widely used in some bacteria, such as the ubiquitous “Acidianus”. Anoxygenic photosynthesis has been found in purple bacteria and a few others.

Is bacterial photosynthesis an anaerobic process?

Bacterial photosynthesis uses water, but not molecular oxygen, as the primary electron donor. However, the process of bacterial photosynthesis occurs aerobically.

Aerobic processes generate ATP by breaking down glucose and are never anaerobic.

Is there a difference between bacterial and plant photosynthesis?

Bacteria that undergo photosynthesis, such as Xenobacteria and heliobacterium, have many similarities in structure to plants or cyanobacteria.

Green sulfur bacteria are one source of hydrogen sulfide gas, which is used by methanogenic archaea in their metabolism.

Is anoxygenic photosynthesis cyclic?

The electron transport chain of anoxygenic phototrophs is cyclic, meaning the electrons used during photosynthesis are fed back into the system, therefore no electrons are left over to oxidize water into oxygen.