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Nitrifying bacteria are chemolithotrophic organisms that include species of genera such as Nitrosomonas, Nitrosococcus, Nitrobacter, Nitrospina, Nitrospira and Nitrococcus. These bacteria get their energy from the oxidation of inorganic nitrogen compounds. [1] Types include ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB).
Frankia is a nitrogen-fixed organism, explaining why it is able to resist heavy metals. [8] [clarification needed] Frankia is a gram-positive Bacteria that is found on the roots of plants. The fact that Frankia is gram-positive means that the bacteria is made up of thick cell walls made out of protein called peptidologlycan. This helps with the ...
Azotobacter chroococcum is a bacterium that has the ability to fix atmospheric nitrogen. It was discovered by Martinus Beijerinck in 1901, and was the first aerobic, free-living nitrogen fixer discovered. [2] A. chroococcum could be useful for nitrogen fixation in crops as a biofertilizer, fungicide, and nutrient indicator, and in bioremediation.
Azotobacter can fix at least 10 μg of nitrogen per gram of glucose consumed. Nitrogen fixation requires molybdenum ions, but they can be partially or completely replaced by vanadium ions. If atmospheric nitrogen is not fixed, the source of nitrogen can alternatively be nitrates, ammonium ions, or amino acids.
Some nitrogen-fixing bacteria have symbiotic relationships with plants, especially legumes, mosses and aquatic ferns such as Azolla. [4] Looser non-symbiotic relationships between diazotrophs and plants are often referred to as associative, as seen in nitrogen fixation on rice roots. Nitrogen fixation occurs between some termites and fungi. [5]
Heterocyst-forming species are specialized for nitrogen fixation and are able to fix nitrogen gas into ammonia (NH 3), nitrites (NO − 2) or nitrates (NO − 3), which can be absorbed by plants and converted to protein and nucleic acids (atmospheric nitrogen is not bioavailable to plants, except for those having endosymbiotic nitrogen-fixing ...
Another example is the cycling of nitrogen. Many lithotrophic bacteria play a role in reducing inorganic nitrogen (nitrogen gas) to organic nitrogen in a process called nitrogen fixation. [28] Likewise, there are many lithotrophic bacteria that also convert ammonium into nitrogen gas in a process called denitrification. [27]
Green sulfur bacteria exhibit activity from a Type-1 secretion system and a ferredoxin-NADP+ oxidoreductase to generate reduced iron, a trait that evolved to support nitrogen fixation. [34] Like purple sulfur bacteria, they can regulate the activity of nitrogenase post-translationally in response to ammonia concentrations. Their possession of ...