Growth, denitrification and nitrate ammonification of the rhizobial strain TNAU 14 in presence and absence Of C2H4 and C2H2
ANNALS OF MICROBIOLOGY, 57 (4):
509-514 (2007)Abstract
Soil-N (NO3-) initiates as far as a threshold concentration is
surpassed manifold physiological reactions on N-2-fixation. Organic N
and ammonium oxidised to NO3- means oxygen depletion. Plants suffering
under O-2 or infection stress start to excrete ethylene (C2H4), C2H4
widens the root intercellulars that O-2-respiration will continue. Now
microbes may more easily enter the plant interior by transforming the
reached methionine into C2H4. Surplus nitrate and C2H4 inhibit
nodulation of leguminous plants. Excess NO3 in the nodulesphere could
be diminished by N-2-fixing bacteria which in addition can denitrify or
ammonify nitrate. Consequently, it was asked whether CA interferes with
the potential of N-2-fixing bacteria to reduce nitrate. The
groundnut-nodule isolate TNAU 14, from which it was known that it
denitrifies and ammonifies nitrate, served as inoculum of a
KNO3-mannitol-medium that was incubated under N-2(-), 1% (v/v)
N-2-C2H4-, and 1% (v/v) N-2-C2H2-atmosphere in the laborator