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2 O + H 2 O (Nitric-oxide reductase) N 2 O + 2 H + + 2 e − → N 2 + H 2 O (Nitrous-oxide reductase) The complete process can be expressed as a net balanced redox reaction, where nitrate (NO 3 −) gets fully reduced to dinitrogen (N 2): 2 NO 3 − + 10 e − + 12 H + → N 2 + 6 H 2 O
Another important environmental issue concerning denitrification is the fact that the process tends to produce large amounts of by-products. Examples of by-products are nitric oxide (NO) and nitrous oxide (N 2 O). NO is an ozone depleting species and N 2 O is a potent greenhouse gas which can contribute to global warming. [3]
Many species of nitrifying bacteria have complex internal membrane systems that are the location for key enzymes in nitrification: ammonia monooxygenase (which oxidizes ammonia to hydroxylamine), hydroxylamine oxidoreductase (which oxidizes hydroxylamine to nitric oxide - which is further oxidized to nitrite by a currently unidentified enzyme ...
Nitrous-oxide reductase is a homodimer that is located in the bacterial periplasm. X-ray structures of the enzymes from Pseudomonas nautica and Paracoccus denitrificans have revealed that each subunit (MW=65 kDa) is organized into two domains. [ 7 ]
Sewage treatment plants mix these organisms as activated sludge or circulate water past organisms living on trickling filters or rotating biological contactors. [5] Aquatic vegetation may provide similar surface habitat for purifying bacteria, protozoa, and rotifers in a pond or marsh setting; although water circulation is often less effective.
Approximately 78% of Earth's atmosphere is N gas (N 2), which is an inert compound and biologically unavailable to most organisms.In order to be utilized in most biological processes, N 2 must be converted to reactive nitrogen (Nr), which includes inorganic reduced forms (NH 3 and NH 4 +), inorganic oxidized forms (NO, NO 2, HNO 3, N 2 O, and NO 3 −), and organic compounds (urea, amines, and ...
The use of nitrites in food preservation is highly controversial [22] due to the potential for the formation of nitroso-compounds such as nitrosamines, N-nitrosamides and nitrosyl-heme. [citation needed] When the meat is cooked at high temperatures, nitrite-cured meat products can also lead to the formation of nitrosamines.
Biological functions of nitric oxide are roles that nitric oxide plays within biology. Nitric oxide (nitrogen monoxide) is a molecule and chemical compound with chemical formula of N O . In mammals including humans, nitric oxide is a signaling molecule involved in several physiological and pathological processes. [ 1 ]