Photosynthetic bacteria are a unique species of microorganisms that use the sun as a source of energy. Plants use a substance called chlorophyll to absorb the sun’s rays and turn it into the nutrients needed for everyday maintenance and growth. Bacteria contain a similar compound called bacteriochlorophyll, which allows them to also photosynthesize. There are three groups of photosynthetic bacteria: Chlorobiacae, Chromatiacae, and Rhodospirillacae. These three groups will be explained later on, but first, it will help to understand what photosynthesis is and how it provides energy to an organism.
The process of photosynthesis is fairly simple and can be reduced to a chemical equation. The sun produces light energy which the bacteria can convert into chemical energy. The energy is primarily used to form carbohydrates a food source for the bacteria, but ultimately will make all the materials of the organism. While not a great deal is known about photosynthetic bacteria, scientists have applied facts known about plants to the bacteria, thinking that both organisms have the same processes. Although it is difficult to say, their theories seem to be correct.
Photosynthesis takes place on the surface of the cell, which is known as the cell membrane, or a thin sheet that covers and protects the bacteria. Embedded in the cell membrane are reaction centers which specifically absorb light energy. These reaction centers exist in the forms of sacs, tubes, or sheets, depending on the amount of surface area that is needed.
Rhodospirillacae are purple bacteria. They are a rod-shaped bacteria, although the length of each rod varies slightly. The purple color of the bacteria makes them distinctive and easy to identify in a mixture. These bacteria can use hydrogen gas as an organic electron donor or can also use succinate or malate, depending on the availability of each compound. Another type is Chromatiacae which is also a purple bacteria. They are short gram-negative rods. Unlike the Rhodospirillacae, they can use sulfur and sulphide as the electron donor. The last kind are the Chlorobiacae which are a green bacteria. They are also a sulfur bacteria.
This is a short summary of the definition of photosynthesis, the different types of photosynthetic bacteria and how they differ from each other. It is important to note that other photosynthetic bacteria may exist and have not been identified yet. These bacteria primarily live in the water and can be difficult to find and isolate, especially if they exist in small quantities. However, these three types are the major and probably the most important kinds of photosynthetic bacteria.