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【目的】从东祁连山高寒草地珠芽蓼内生细菌中筛选和鉴定具有固氮能力和拮抗能力的内生细菌。【方法】采用16S rRNA基因序列同源性分析和生理生化指标测定方法对该菌株进行鉴定。【结果】从珠芽蓼中分离获得的21株内生细菌中6株内生菌具有固氮能力,76.2%具有抑菌能力,其中5株内生细菌对5种以上的病原菌有抑制作用;菌株Z19具有较强固氮能力和分解纤维素的能力,其纤维素溶解圈直径与菌落直径比达3.33,产生的纤维素酶活性为0.31 U,且对辣椒立枯丝核病菌(Rhizoctonia solani)、油菜菌核病菌(Sclerotinia sclerotiorum)、番茄灰霉病菌(Botrytis cinerea)、小麦根腐病菌(Bipolaris sorokiniana)和番茄早疫病菌(Alternaria solani)具有较强拮抗能力;经PCR扩增和测序,获得了菌株Z19的固氮基因(nifH)序列和16S rRNA基因序列,在GenBank中的登录号分别为EU693340和EU236746;菌株Z19呈革兰氏阳性,杆状,产芽孢。【结论】结合生理生化特征及16S rRNA基因序列同源性比较,鉴定其为枯草芽孢杆菌(Bacillus subtilis)。
【Objective】 Endophytic bacteria with nitrogen fixation ability and antagonism ability were screened and identified from endophytic bacteria of Polygonum capitatum in alpine grassland of Eastern Qilian Mountains. 【Method】 The 16S rRNA gene sequence homology analysis and physiological and biochemical indexes were used to identify the strain. 【Result】 Among the 21 endophytic bacteria isolated from Polygonum viviparum, 6 strains of endophytic bacteria had nitrogen fixation capacity and 76.2% had antibacterial activity. Among them, 5 strains of endophytic bacteria inhibited the growth of more than 5 pathogens. Strain Z19 Has a strong ability of fixing nitrogen and decomposing cellulose, and the ratio of the diameter of cellulose dissolving ring to the diameter of the colony reaches 3.33 and the activity of cellulase produced is 0.31 U, and the activity of Rhizoctonia solani, Sclerotinia sclerotiorum, Botrytis cinerea, Bipolaris sorokiniana and Alternaria solani were highly antagonistic. After PCR amplification and sequencing, strain Z19 (NifH) sequence and 16S rRNA gene sequence in GenBank were EU693340 and EU236746 respectively. Strain Z19 was Gram-positive, rod-shaped and sporulated. 【Conclusion】 Bacillus subtilis was identified by comparing its physiological and biochemical characteristics and 16S rRNA gene sequence homology.