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Oxygen likely affects denitrification in multiple ways—because most denitrifiers are facultative, oxygen can inhibit rates, but it can also stimulate denitrification by facilitating nitrification and the production of nitrate. In wetlands as well as deserts, [21] moisture is an environmental limitation to rates of denitrification.
Nitrification is the biological oxidation of ammonia to nitrate via the intermediary nitrite. Nitrification is an important step in the nitrogen cycle in soil . The process of complete nitrification may occur through separate organisms [ 1 ] or entirely within one organism, as in comammox bacteria.
There is a great diversity in biological traits. [1] Denitrifying bacteria have been identified in over 50 genera with over 125 different species and are estimated to represent 10-15% of bacteria population in water, soil and sediment. [3] Denitrifying include for example several species of Pseudomonas, Alcaligenes, Bacillus and others.
The conversion of nitrogen can be carried out through both biological and physical processes. Important processes in the nitrogen cycle include fixation, ammonification, nitrification, and denitrification. The majority of Earth's atmosphere (78%) is atmospheric nitrogen, [16] making it the largest source of nitrogen.
The evolutionary motivation for a decoupled, two-step nitrification reaction is an area of ongoing research. In 2015, it was discovered that the species Nitrospira inopinata possesses all the enzymes required for carrying out complete nitrification in one step, suggesting that this reaction does occur. [12] [13]
Biological nitrogen fixation (BNF) occurs when atmospheric nitrogen is converted to ammonia by a nitrogenase enzyme. [1] The overall reaction for BNF is: N 2 + 16ATP + 16H 2 O + 8e − + 8H + → 2NH 3 +H 2 + 16ADP + 16P i. The process is coupled to the hydrolysis of 16 equivalents of ATP and is accompanied by the co-formation of one equivalent ...
Aerobic denitrification, or co-respiration, the simultaneous use of both oxygen (O 2) and nitrate (NO − 3) as oxidizing agents, performed by various genera of microorganisms. [1] This process differs from anaerobic denitrification not only in its insensitivity to the presence of oxygen, but also in its higher potential to form nitrous oxide ...
Microbial simultaneous nitrification-denitrification is the conversion of the ammonium ion to nitrogen gas in a single bioreactor. The process is dependent on floc characteristics, reaction kinetics, mass loading of readily biodegradable chemical oxygen demand {rbCOD}, and the dissolved oxygen {DO} concentration.