User:A chavez St/Rhodopseudomonas palustris

(1)http://www.nature.com/nbt/journal/v22/n1/abs/nbt923.html

The bacterium Rhodopseudomonas palustris is a purple non-sulfur bacteria. This bacterium has been found to grow in swine waste lagoons, earthworm droppings, marine coastal sediments and pond water. Even though purple non-sulfur bacteria are normally photoheterotrophic organism R. palustris has the ability to switch between the four different modes of metabolism that support life, which are: photoautotrophic, photoheterotrophic, chemoautotroph and chemoheterotrophic. This means that this bacterium can grow with or without oxygen, it can use light, inorganic compounds or organic compounds for energy, it can acquire carbon from either carbon dioxide fixation or green plant-derived compounds and it can also fix nitrogen. This metabolic versatility has raised interest in the research community and make this bacterium suitable for potential use in biotechnological applications.

Currently efforts are being made to understand how this organism integrates the various metabolic modules in response to environmental changes. The complete genome of the strain Rhodopseudomonas palustris CGA009 was sequenced (List of sequenced bacterial genomes) in hope of getting more information about how the bacterium senses environmental changes and how it regulates its metabolic pathways accordingly. It was found that R. palustris has genes that encode for proteins that make up light harvesting complexes and photosynthetic reaction centres. Light harvesting complexes and photosynthetic reaction centers are typically found in photosynthetic organisms like green plants. Besides being a photosynthetic bacteria R. palustris can modulate photosynthesis according to the amount of light available. For instance in low light circumstances it responds by increasing the level of these light harvesting (LH) complexes that allow light absorption.

R. palustris also has genes that encode for the protein RubisCO, an enzyme that is necessary for carbondioxide fixation (see Carbon fixation) found in plants and other photosynthetic organisms. The genome reveals also the existence of proteins involved in nitrogen fixation (see Diazotroph).

Purple photorophic bacteria are of great interest due their use in biotechnological applications. These bacteria can be used for 'bioplastic' synthesis and hydrogen production. R. palustris differs from other purple bacteria due to is ability to modulate photosynthesis according to the amount of light available and its ability to degrade aromatic compounds found in agricultural and industrial waste. It also has the unique characteristic of encoding for a vanadium containing nitrogenase which produces as a byoproduct of nitrogen fixation three times more hydrogen than the nitrogenase of other bacteria (molybennum-containing nitrogenase). The potential to manipulate R. palustris to be used as hydrogen production source and biodegradation still requires more detailed knowledge of its metabolic pathways and regulation mechanisms.