水稻根际固氮菌NX-2的分离鉴定及其培养条件优化

Isolation, Identification and Optimization of culture conditions of Nitrogen-Fixing Bacteria NX-2 from Rice Rhizosphere

筛选高效固氮能力的植物根际促生菌是研发微生物肥料的关键。研究从水稻根际土壤中分离筛选得到一株固氮菌NX-2,利用乙炔还原法测定其固氮酶活可达16.18μmol/(m L·h)(以C2H4浓度计)。通过形态观察、生理生化特性和16S r DNA序列分析,菌株NX-2被鉴定为褐球固氮菌。进一步研究其生长特性,结果显示最佳培养条件为培养温度28℃、初始p H值6.5、接种量3%。

It is a key issue to screen the rhizosphere promoting bacteria of high efficient nitrogen fixing ability for the development of microbial fertilizer. In this study a nitrogen-fixing bacteria NX-2 was isolated from rice rhizosphere soil. Nitrogenase activity was measured by acetylene reduction at 16.18 μmol/（mL·h） calculated C2H4 concentration. Through morphological observation, physiological and biochemical characteristics and 16 S r DNA sequence analysis, the strain NX-2 was identified as Azotobacter. Its growth characteristics were further studied, the results showed that the optimal fermentation condition was the initial temperature 28℃, pH 6.5, inoculum size 3%.