Nitrogen is an essential nutrient. As N2 gas it is a major constituent of the atmosphere, but N2 is chemically inert and therefore unavailable as a source of nitrogen for use by most living organisms. However, some bacteria have the ability to reduce N2 and thereby “fix” atmospheric nitrogen using the enzyme nitrogenase. Many leguminous plants have capitalised on this special bacterial asset by going into partnership with nitrogen-fixing bacteria called rhizobia. In return for supplying nutrients to the bacteria, the plants receive a supply of reduced nitrogen. In essence, the legumes create a highly specialised environment within which the bacteria fix nitrogen. These specialised plant structures are called nodules; usually they are found on roots, but they also occur on the stems of some legumes.
KeywordsProline Flavonoid Succinate Acetylene Oligosaccharide
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