Not all but some specific bacteria can perform photosynthesis.
Some bacteria can produce their food via photosynthesis like autotrophs using photoreceptor pigments in their membrane.
Are most bacteria photosynthetic?
Unfortunately, most bacteria are not photosynthetic.
Photo-autotrophism in bacteria is rare, as they have mostly lost this ability over the millennials during evolution.
Most bacteria are either heterotrophs or parasites. Photoautotrophic bacteria are present mainly due to adaptations to their environments.
Image: Wikipedia
Are all bacteria photosynthetic?
No, the majority of bacterial organisms are not photosynthetic.
The majority of bacterial species depend on other organisms as a food source i.e. they are either heterotrophs or parasites.
Most bacteria might have started out as autotrophs but slowly lost of them lost the ability altogether, excepting some. Probably due to the commencement of the ice age, which lasted over a million years, when photosynthesis was quite impossible.
What type of bacteria is photosynthetic?
There are 2 main types of photosynthetic bacteria- these include those that use photosynthesis and others that use chemosynthesis.
Bacterial photosynthesis depends on the source of Hydrogen which can be water or Hydrogen sulphide. In either case, we have different by-products.
Bacteria that have chloroplasts can use water in the process of photosynthesis, there producing oxygen. Other bacteria that do not possess chloroplasts are usually equipped with photosynthetic pigments. However, these receptors cannot use water and hence these bacterial species use H2S as the source of oxygen, Thereby they produce sulphur gas as a by-product of photosynthesis.
Image: Wikipedia
Types of photosynthetic bacteria:
Bacteria capable of photosynthesis are mainly grouped into 5 distinct groups.
Cyanobacteria: Also called blue-green algae, cyanobacteria release oxygen as a byproduct of photosynthesis like that in plants. But unlike plants do not contain all the 4 components of the chlorophyll pigment, instead, they contain either one or two of them. Biologically they are called oxidative phototrophs.
Purple Bacteria or proteobacteria: Phyllum proteobacteria consists of some specific gram-negative bacteria belonging to the genera– Escherichia, Vibrio and Salmonella. Unlike the above type, purple bacteria perform anoxygenic photosynthesis, i.e. they do not evolve oxygen.
Heliobacteria: Heliobacteria are a group of gram-positive bacteria belonging to the phylum Firmicutes. Heliobacteria are biologically considered to be obligate anaerobes. Though they can perform simple photosynthesis they cannot exhibit phototrophic growth.
Chlorobi or green sulfur bacteria: Chlorobi is a phylum of obligatory anaerobes that can only thrive in anoxic environments. As the name indicates, green sulfur bacteria live in habitats rich in sulfur and where the intensity of light is comparatively low. They live in the lowermost section of the photic zone in ocean habitats.
Chloroflexi or chlorobacterium: Phylum Chloroflexi, includes bacteria with a wide range of features. Chlorobacterium has 2 main types- aerobic thermophiles and anoxygenic photoautotrophs. The former uses oxygen for its chemoheterotrophic existence. On the other hand, the latter uses light to photosynthesize.
Members of this phylum have a wide range of ecological and physiological characteristics and can be found in a variety of environments, including sediments and hot springs.
Photosynthetic bacteria characteristics:
- Photosynthetic bacteria usually have some photochromatic pigments or chlorophyll components to be able to capture light.
- Just like other autotrophs, they produce energy which can be used as food or for other purposes.
- Most photosynthetic bacteria love in places where other food sources are scarce.
- They are a major source of Carbon that is fixed by the ocean.
Which bacteria are not photosynthetic?
Excepting the five types of bacteria mentioned above, all other bacteria are incapable of photosynthesis.
Bacteria in most cases are heterotrophs or parasitic in nature, i.e. they depend on other sources for their replenishment.
Even photosynthetic bacteria like heliobacteria cannot use the food they produce for their autotrophic growth. They too need to consume and acquire replenishment from the environment.
Bacteria do not have any specialized structure and usually swallow their food whole and then digest it by consuming it into their body.
Photosynthetic bacteria examples:
Examples of photosynthetic bacteria include:
- Cyanobacteria or blue-green species include Synechococcus elongatus, Nostoc punctiforme etc
- Purple bacteria examples include: Rhodobacter capsulatus, Chromatium okenii, Rhodopseudomonas palustris etc.
- Best known Heliobacteria examples include Heliobacterium mobilis and Heliobacterium modesticaldum
- Green sulfur bacteria examples include Pelodictyon phaeoclathhratiforme, Chlorobium phaeobacteroides and more.
Are decaying bacteria photosynthetic?
No decaying bacteria do not perform photosynthesis.
Decaying bacteria are basically saprophytic, that is they consume the nutrients from dead and decaying matter.
If these bacterial species could perform photosynthesis they would not be depending on the dead matter for sustenance. These bacteria species usually break down these dead materials and break them down. In this way, they have often been considered cleaners, and help the nutrients to return to nature.
Are aerobic bacteria photosynthetic?
Not all aerobic bacteria perform photosynthesis.
Similarly, not all photosynthetic bacteria are aerobic. The ability to perform photosynthesis depends on the presence of pigments in the bacteria that are photoreceptive.
Cellular respiration depends if the bacteria species is living in an environment where oxygen is abundant or not. Most bacterial species naturally are usually aerobic or facultative anaerobes. Facultative anaerobic bacteria can shift between aerobic and anaerobic respiration depending on the availability of oxygen in their environment.
However, some bacteria are also obligate anaerobes because they survive in severely oxygen-depleted environments. However, even these types of bacteria are photosynthetic.
Photosynthetic bacteria for plants:
Photosynthetic bacteria are really useful to plants:
- They act as biofertilizers.
- They naturally fix the soil with nitrogen.
- They also fix carbon sulphur, hydrogen and carbon enriching soil.
- They are also involved in nitration and denitration of the nitrogen that is fixed in the soil.
- They allow for the better regulation of the nitrogen and carbon cycle.
Image: Wikipedia
How do photosynthetic bacteria grow?
Photosynthetic bacteria grow by producing food by photoautotrophism.
They produce their own food by photosynthesis and use it to grow in size and then simply divide, to form their progenesis.
Some exceptions include the heliobacteria, which do photosynthesize but are unable to use the produced food in autotrophic growth. Instead, they feed n other materials like all other bacterial organisms.
Function of photosynthetic bacteria:
Functions of photosynthetic bacteria include:
- Ability to fix gases like nitrogen, Sulphur, Hydrogen and Carbon. Especially in the soil and in the ocean.
- Nitrification of the soil by these bacteria allows atmospheric nitrogen to be incorporated into the soil in the form of compounds.
- Nitrification and denitrification of soil make it richer and provide plants with ample nutrients.
- They are often used in wastewater management industries for the process of the water purification process.
- They are also used as biofertilizers and animal feed for natural enrichment.
Do photosynthetic bacteria evolve oxygen?
Cyanobacteria and blue-green algae do evolve oxygen as a by-product of photosynthesis.
Only bacteria that contain chlorophyll are capable of producing oxygen as a gas.
Not all photosynthetic bacteria contain chlorophyll. Excepting cyanobacteria, the other 4 types of photosynthetic bacteria contain bacteriochlorophyll or some other photopigments. These other bacteria do not use water as an electron donor. While some others are anaerobic facultative or obligate, hence they do not evolve oxygen.
What do photosynthetic bacteria release?
The byproducts of the photosynthetic reaction in these bacteria mainly depend on the electron donor.
If the electron donor is water, oxygen is released, but not all bacteria use water as their electron donor.
Cyanobacteria containing chlorophyll use water as their electron donor. Hence the chemical reaction produces Oxygen. On the other green sulphur bacteria living in hot springs uses H2S as their electron donor. In the latter case, Sulphur gas s released as a byproduct.
Image: Wikipedia
Do photosynthetic bacteria use cellular respiration?
No, not all photosynthetic bacteria do not use cellular respiration.
If some bacteria are obligate anaerobes they do not perform cellular respiration under any condition.
Varieties like cyanobacteria and green sulfur bacteria do have access to oxygen so they undergo cellular respiration. But most bacterial species are facultative(i.e. by choice depending on availability) anaerobes or obligate anaerobes by nature. These photosynthetic bacteria species live in environments that are normally devoid or short in oxygen supply.
Conclusion:
This shows that some bacteria re capable of performing photosynthesis, due to the presence of photoreceptive pigments in them, but the process may or may not involve the evolution of oxygen as seen in plants.
Also Read:
- Incomplete dominance example
- Are proteins soluble
- Cofactor examples
- Miscible examples
- Monogenea characteristics
- Autotroph
- Carrier proteins types
- Non native species examples
- Types of eukaryotic chromosomes
- Bacterial enzyme example
I am Trisha Dey, a postgraduate in Bioinformatics. I pursued my graduate degree in Biochemistry. I love reading .I also have a passion for learning new languages.
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