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Rhodopseudomonas palustris CGA009
   
   
 

Photo: Caroline Harwood
Rhodopseudomonas palustris is a purple non-sulfur phototrophic bacterium commonly found in soils and water that makes its living by converting sunlight to cellular energy and by absorbing atmospheric carbon dioxide and converting it to biomass. This microbe can also degrade and recycle a variety of aromatic compounds that comprise lignin, the main constituent of wood and the second most abundant polymer on earth. Because of its intimate involvement in carbon management and recycling, R. palustris has been selected by the DOE Carbon Management Program to have its genome sequenced by the JGI.

Rhodopseudomonas palustris is a common soil and water bacterium that makes its living by converting sunlight to cellular energy and by absorbing atmospheric carbon dioxide and converting it to biomass. This microbe can also degrade and recycle components of the woody tissues of plants (wood is the most abundant polymer on earth). Because of its intimate involvement in carbon management and recycling, R. palustris was selected by the DOE Carbon Management Program for genome sequencing by the JGI.

R. palustris is acknowledged by microbiologists to be one of the most metabolically versatile bacteria ever described. Not only can it convert carbon dioxide gas into cell material but nitrogen gas into ammonia, and it can produce hydrogen gas. It grows both in the absence and presence of oxygen. In the absence of oxygen, it prefers to generate all its energy from light by photosynthesis. It grows and increases its biomass by absorbing carbon dioxide, but it also can increase biomass by degrading organic compounds including such toxic compounds as 3chlorobenzoateto cellular building blocks. When oxygen is present, R. palustris generates energy by degrading a variety of carboncontaining compounds (including sugars, lignin monomers, and methanol) and by carrying out respiration.

R. palustris undergoes two major developmental processes. The first is cell division by budding. This process of asymmetric cell division results in two different kinds of daughter cellsone a motile swarmer cell and the other a stalked nonmotile cell. The second is the differentiation of an elaborate system of intracytoplasmic membrane vesicles when cells run out of oxygen and are placed in light. The membranes are used to house photosynthetic pigments and associated proteins. Budding division and differentiation to photosynthetically competent cells both require a temporally regulated program of gene expression followed by a pattern of precise localization of protein products.

R. palustris has a genetic system -- genes can be moved in and out of this bacterium easily, and specific genes thus can be targeted for mutagenesis -- which will allow researchers to rapidly apply information gained from genome sequencing to the developing area of functional genomics.

Bioenergy from Industrial Waste

Energy is the source of economic growth and energy consumption reflects the state of development of the country. Since fossil fuels like coal, gas, and oil are exhaustible, nuclear energy has its own limitation and non-conventional energy such as wind power, tidal and solar are not sufficiently exploited, bioenergy can prove to be a practical approach to obtain cheap, clean to use and unlimited source of energy. Waste to energy concept is now accepted as attractive proposal, particularly with the biotechnological progress in improving the efficiency of microorganisms involved, bioreactors used control on processes. It is not the energy production for distribution and use, but it is to save energy expenditure on waste treatment and instead to meet part of overheads.