Synopsis: Regulation of nitrogen assimilation.
Chapters 12 and 18.4
Inorganic nitrogen assimilation versus dissimilation.
(primarily a waste product of deamination of amino acids, essentially
(biosynthetic incorporation into amino acids, routes subject to some
complex regulation by ammonium concentration) versus
electron donor in
nitrifying bacteria, unregulated but sensitive to absence of oxygen).
nitrate reduction (biosynthetic nitrate reduction to nitrite and thence to
ammonium, repressed by ammonium, induced by nitrate, insensitive to oxygen tension) versus
nitrate reduction (alternative electron acceptor in respiration, membrane and electron
transport associated nitrate reduction to nitrite, insensitive to ammonium, induced by nitrate, repressed
nitrite reduction (biosynthetic nitrite reduction to ammonium, repressed by
ammonium, induced by nitrate/nitrite, insensitive to oxygen tension) versus
reduction (alternative electron acceptor in respiration). There are two routes of dissimilatory nitrite
reduction to ammonium
by enterics such as
, (insensitive to ammonium, induced by
nitrite, repressed by oxygen; also called nitrite respiration);
reduction to nitric oxide, then nitrous oxide and ultimately dinitrogen
] in a process
called denitrification by various facultative anaerobic, obligate respiratory microorganisms
(insensitive to ammonium, induced by nitrite, repressed by oxygen).
dinitrogen reduction to ammonium, also called nitrogen fixation (a strictly
biosynthetic process, repressed by ammonium and nitrate, and, in most cases, by oxygen).