耐盐碱固氮菌的分离筛选及固氮特性研究

采用改良的无氮Burk’s培养基,从松嫩平原盐碱化土壤中分离出2株具有耐盐碱能力固氮菌,编号为FC5和FC10。采用扫描电镜对固氮菌的形态观察和生理生化指标测定表明,FC5和FC10属于固氮菌属。探讨了FC5和FC10对酸碱度、碳源、渗透压和NH4+浓度的适应性,结果表明:2株菌具有一定的耐盐碱能力,FC10的固氮酶活在pH值为7.7时达到峰值,FC5当pH值为8.2时达到最大值;FC5和FC10在利用乳糖和葡萄糖时表现出了较高的固氮酶活性;FC5和FC10对渗透压具有较强的适应性;当NH4+浓度在0.2～2mmol/L时,固氮酶活性迅速降低。

Isolating Screening and Nitrogen Fixation Capability of Salt-tolerant Azotobacter

Two strains of salt tolerance Azotobacter named FC5 and FC10 were isolated using improved non-nitrogenous Burk’s culture medium from saline soils in Songnen Plain. On the basis of its physiological characteristics and morphological observation using SEM, FC5 and FC10 were identified as Azotobacter. Adaptability study of FC5 and FC10 for pH, carbon source, osmotic pressure and concentration of NH4+ showed that the two strains have proper ability of salt tolerance, with nitrogenase of FC10 at maximum in pH 7.7 and nitrogenase of FC5 at maximum in pH 8.2. Both FC5 and FC10 have high nitrogenase with lactose and glucose as substrate as well as high adaptability for osmotic pressure. Nitrogenase was reduced immediately with concentration of NH4+ 0.2～2mmol/L.