几种禾草内生固氮菌的分离及固氮活性测定

Isolation of endophytic diazotrophic bacteria from several gramineae grasses and determination of their nitrogenase activity

从13种禾草组织中分离内生细菌，研究比较不同禾草品种，不同组织中内生细菌的菌群密度和分布特点；筛选内生固氮菌菌株，经乙炔还原法测定其固氮酶活性。结果表明，不同禾草品种的内生细菌菌群密度有较大差异，菌群密度为8．70×10^4～8．06×10^4CFU／g鲜重。根组织中菌群密度高于叶。采用CCM培养基结合无氮选择性培养基筛选获得21株内生固氮菌菌株，其固氮酶活性在8～2865nmol／h·mL。研究结果证明从禾草中可分离到具有高固氮酶活性的菌株，具有开发应用的潜力。

This study evaluated community structures in different cultivars and tissues of endophytic bacteria isolated from 13 gramineae grass species in Xinjiang, and their nitrogenase activity was detected using an acetylene-reduction assay. The population densities of the endophytic bacteria varied depending on gramineae grass species. The quantities of endophytes in different cultivars varied from 8. 70 × 10^4 to 8.06 × 10^6 CFU/g fresh weight, and were much higher in roots than in foliage. Twenty-one endophytic diazotrophic bacterial strains were isolated using CCM medium combined with selected nitrogen-free medium, and the detected nitrogenase activity ranged from 8 to 2 865 nmol/h · mL. The research revealed that endophytic bacterial strains with high nitrogenase activity can be isolated from gramineae grass, and have considerable application potentials to be used as biofertilizers.