| Summary: | 碩士 === 國立中興大學 === 植物學系 === 82 === The highest of nitrogenase specific activity (17 mU/mg prot.
24mU/mg prot.) heterocyst frequency (7.4 % 7.7 %) growth rate
(0.083 h-1 0.089 h-1) doubling time (8 h 7 h) and GS specific
activity (507 mU/mg prot.592 mU/mg prot.) were obtained from
Anabaena sp. CH1 and CH3 grown in the presence of atmospheric
N2. Most of them more sensitive to NH4+, growth was inhibited
when the concentration higher than 0.25 mM NH4Cl NH4NO3
(Anabaena CH1) or 0.5 mM NH4Cl NH4NO3 (Anabaena CH3). When
Anabaena sp.CH1 and CH3 were grew in 0.03-0.1 mM NH4+-
containing media, the GOGAT specific activity was not affected
in the presence of KNO3 NH4Cl and NH4NO3. In addition, the GS
specific activity was 72-76 % as compared to that in N2-grown
cultures, and the ADH specific activity GDH specific activity
were stimulated 195-199 % 257-260 %. For these isolates grown
in the medium containing 0.05 mM NH4Cl 0.03 mM NH4NO3 (Anabaena
CH1)or 0.1 mM NH4Cl 0.05 mM NH4NO3 (Anabaena CH3 ).In contrast,
most of them were very insensitive to NO3-. These isolates grew
well in the medium containing KNO3 up to 30 50 mM{0.081 h-1
0.054 h-1(Anabaena CH1);0.084 h-1 0.073 h-1 (Anabaena CH3)} ,
but the growth were inhibited when the concentration higher
than 70 mM KNO3. However, with the increase of the KNO3 NH4Cl
and NH4NO3 concentration in medium, their nitrogenase specific
activity growth rate heterocyst frequency and GS specific
activity declined rapidly. Energy were needed for nitrogen
fixation and ammonium assimilation in Anabaena sp.CH1 and CH3,
The energy produced from photosynthesis was believed to be the
main source for nitrogen fixation and ammonium assimilation of
them.
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