【摘要】 采用乙炔还原法对从圆果雀稗(Paspalum orbiculare)根、茎中分离到的5株内生固氮菌(POJy11、POG12、POGy22、POGy612、POG4)的固氮特性进行了研究。结果表明,POGy612、POG4固氮的pH适应范围是6.0-10.0,其余3株菌为6.0-8.0;POGy22固氮的最适温度为35℃,其余4株菌为30℃;随着NH4+浓度和NaCl浓度的升高,菌株固氮活性总体呈下降趋势,其中POGy22的固氮活性受NH4+抑制最明显,NH4+浓度为1.0 mmol/L时,已无固氮活性,但POGy612在NH4+浓度为2.5 mmol/L时的固氮活性最高,达到1 045.0 nmol ml-1h-1,POJy11、POGy22在NaCl浓度为0.5%时的固氮活性最高,分别达到735.5 nmol ml-1h-1、703.0 nmol ml-1h-1。更多还原

【Abstract】 Five endophytic diazotroph strains,including POJy11,POG12,POGy22,POGy612 and POG4 from rhizosphere and stalks of Paspalum orbiculare,were studied in acetylene reduction activity(ARA).ARA was maximal at pH 6.0-10.0 in POGy612 and POG4 strains and did at pH 6.0-8.0 in POJy11,POG12 and POGy22 strains.The maximum activity occurred at 35℃ in POGy22 strain and did at 30℃ in the other strains.The activity in those strains remarkably declined as NH4+ or NaCl concentration increased.ARA was mostly inhibited by NH4+ in POGy22 strain and lost over 1.0 mmol/L NH4+.ARA showed a peak of activity at 2.5 mmol/L NH4+ in POGy612 strain and did at 0.5% NaCl in POJy11 and POGy22 strains.更多还原