狗牙根内生固氮菌生长条件

从已分离的多个狗牙根(Cynodon dactylon)内生固氮菌株中筛选到两株固氮酶活性较高的菌株7D和BM13,为明确固氮菌株对环境因子的适应性,研究了在不同的生长环境条件下菌株的生长量。采用Ashby无氮培养基,测定了温度、pH、渗透压以及不同氮源和碳源等环境条件对固氮菌生长的影响。结果表明,在10~40℃的温度范围内、pH值3.92~9.64的酸碱环境和30g·L~(-1) NaCl的高渗透压下,固氮菌7D和BM13均能正常生长;菌株能耐受0~10mmol·L~(-1)的NH_4~+和NO_3~-,而且能利用蔗糖、甘油、麦芽糖、甘露醇和葡萄糖等多种碳源生长。说明狗牙根内生固氮菌株7D和BM13对环境因子有很强的抗逆性和适应性,但两菌株之间存在一定差异,可望进一步研发成为优良的固氮微生物肥料生产菌种。

Growth conditions of endophytic diazotroph isolated from Cynodon dactylon

Effects of environmental factors on the growth of endophytic diazotroph strains 7D and BM13 isolated from Cynodon dactylon were investigated in our experiment.In this study,strains 7D and BM13 were exam-ined for their adaptability to the stress of temperature,pH,NaCl,NH4 +,NO3 - and carbon sources by Ashby media.The results showed that the two strains could grow under wide range of temperature of 10~40 ℃ and pH from 3.92~9.64.The strains could also tolerate NaCl concentrations of 30 g.L-1 ,NH4 + and NO3 - con-centrations of 0~10 mmol.L-1 ,respectively.The strains were capable of using various carbon sources.It was suggested that the strains 7D and BM13 had superior tolerance to stress of diverse environment factors,but their tolerance abilities differed partly.Endophytic diazotroph strain is a candidate to be further developed for microbial fertilizer production.