Photosynthetic bacteria
Photosynthetic bacteria
Photosynthesis is the mechanism through which prokaryotes (such as photosynthetic bacteria) transform energy from the sun into chemical energy. As a result of their ability to generate their energy from inorganic materials found in their environment, they are also categorized as photoautotrophs. They are therefore not entirely reliant on other organic species for energy.
Numerous varieties of photosynthetic bacteria are seen in both aquatic and terrestrial habitats. Various organisms also function as primary producers in these areas, such as maritime habitats, where the most widespread photosynthetic bacteria may be found. As a result, they play a critical part in the food chain.
They are typically separated into five major groupings, which include:
1. Cyanobacteria
Cyanobacteria also called “blue-green algae,” are Gram-negative bacteria that are frequently present in aquatic habitats. Although the phylum Cyanobacteria has more than 2,000 recognized species, it is thought that there are more than 6,000 species spread across various ecosystems worldwide.
Some of these species can be found in symbiotic relationships with different plants and lichens due to their capacity to fix nitrogen. However, a large number of different species can be discovered existing naturally in soil and water.
Oxygen is released during photosynthesis in cyanobacteria, just like it is in plants and algae. Oxygenic photosynthesis is the name given to this form of photosynthesis. As a result, these bacteria are categorized as oxygenic phototrophs. They do, however, also display variety and adaptability in their pigmentation, according to research.
2. Proteobacteria
The Proteobacteria phylum includes the second category of photosynthetic bacteria. Proteobacteria are widespread Gram-negative bacteria that share similarities with cyanobacteria. Salmonella, Escherichia, and Vibrio are only a few of the harmful taxa found in this phylum, unlike Cyanobacteria.
According to research, there are more than 1,600 species spread among five primary classes: Alphaproteobacteria, Betaproteobacteria, Epsilonproteobacteria, Gammaproteobacteria, & Deltaproteobacteria. The Phylum Proteobacteria contains over 460 genera. Members of such phylum Proteobacteria are mostly linked to anoxygenic photosynthesis, in contrast to Cyanobacteria, which are oxygenic photosynthetic bacteria.
Nevertheless, several aerobic species were discovered in a variety of settings around the globe. Purple bacteria that are capable of photosynthesis have already been proven to solely consist of a solitary photosystem (bacteriochlorophyll) inside the internal membrane, in contrast to plants and other photosynthetic bacteria (such as Cyanobacteria).
3. Heliobacteria
Heliobacteria, a subclass of Gram-positive bacteria within phylum Firmicutes, were first identified in 1983. Most known members of these groups also are capable of nitrogen fixation, just like some Cyanobacteria. In contrast to other types of soil, rice paddy soil contains a large number of Heliobacteria species.
Because they are obligate anaerobes, heliobacteria are extremely sensitive to oxygen. They can so do photosynthesis but do not produce oxygen. Heliobacteria have been demonstrated to be unable to grow through autotrophic growth while being capable of simple photosynthesis. Therefore, photosynthesis plays a crucial role in nitrogen fixation in this situation.
Heliobacteria differ from other photosynthesis-capable bacteria in that they have bacteriochlorophyll g, a special photosynthetic pigment (BChl g).
4. Chlorobi
Chlorobi, also referred to as the green sulfur bacteria, is a phylum of obligate anaerobic bacteria that can only exist in anoxic environments. Members of this species are typically observed in habitats rich in sulfur and characterized by low light intensities, as suggested by their name.
They can be located in the lowermost region of the photic zone in marine environments. The area or layer that is close to the ocean’s surface is known as the photic zone. In this place, they can absorb the light energy needed for photosynthesis. Green sulfur bacteria can obtain light energy and are shielded from ambient oxygen by being localized in the lowermost region of the photic zone. They are extremely oxygen sensitive.
5. Chloroflexi
Chloroflexi, also referred to as Chlorobacteria, is a phylum comprising bacteria made up of bacteria with various properties. For instance, whereas some organisms live chemoheterotrophic lives as aerobic thermophiles that need oxygen, other species are anoxygenic photoautotrophs that can do photosynthesis utilizing light energy.
Members of this phylum can be found in a variety of environments, such as sediments and hot springs, and are environmentally and physiologically diverse.
The majority of Chloroflexi classes are distinguished by filamentous morphologies. Phototrophic bacteria only make up the class Chloroflexia, usually referred to as filamentous green non-sulfur bacteria, within the phylum Chloroflexi.
