Photosynthetic bacteria have been around for longer than the Earth’s atmosphere could sustain human life. It was only recently though that scientists began to unravel the mystery of how these micro-organisms execute the mechanisms of photosynthesis.
While scientists still have not been able to put all the pieces of the photosynthetic bacteria puzzle in the right places, they are actively studying them and are gaining valuable knowledge about the way they photosynthesize and how they have evolved. In fact, they believe that these micro-organisms may have had a huge impact on why the world evolved the way it did, and may show potential for life in places deemed uninhabitable, including extreme climates like Antarctica and even other planets.
Most persons are introduced to photosynthesis in relation to plants and algae. However, much of our understanding about how photosynthetic organisms harvest sunlight and convert it to more useful forms developed from research involving photosynthetic bacteria. Research has shown that the process of photosynthesis in purple non-sulphur bacteria (Rhodospirillaceae) is similar to photosynthesis in green plants but is less complicated and better understood.
Other forms of these micro-organisms identified by scientists include cyanobacteria, purple sulphur bacteria, green sulphur bacteria, heliobacteria and green gliding bacteria. It’s quite possible that there could be more out there that have not been discovered yet. Some may exist in small quantities or in places that make them difficult to find.
What are photosynthetic bacteria?
Much like the name suggests, these micro-organisms are special types of bacteria that contain light absorbing pigments and reaction centers which make them capable of converting light energy into chemical energy.
Cyanobacteria contain chlorophyll while other forms of bacteria contain bacteriochlorophyll. Although bacteriochlorophyll resembles chlorophyll, it absorbs light of a longer wavelength than chlorophyll. Bacteriochlorophyll a is the most common form of bacteriochlorophyll but other forms include b, c, d, e, f and g.
Bacteria that contain bacteriochlorophyll do not use water as an electron donor and therefore do not produce oxygen. This is known as anoxygenic photosynthesis. Cyanobacteria perform photosynthesis using water as an electron donor in a similar manner to plants. This results in the production of oxygen and is known as oxygenic photosynthesis.
Classification of Photosynthetic Bacteria
The slide presentation below provides additional information about photosynthetic bacteria.
Useful Applications for Photosynthetic Bacteria
Photosynthetic bacteria are currently being used in various applications which include water purification, bio-fertilizers, animal feed and bioremediation of chemicals among many others. They are used in the treatment of polluted water since they can grow and utilize toxic substances such as H2S or H2S203.
Researchers at Harvard’s Wyss Institute have engineered photosynthetic bacteria to produce simple sugars and lactic acid. In the video below, Dr. Jeffrey Way explains the science behind the innovation and the potential benefits of this technology.