高寒草地紫花针茅拮抗内生细菌263ZY2的功能测定及其鉴定

Function determination and identification of endo⁃phytic bacteria 263ZY2 from Stipa purpurea in Alpine Grassland

【目的】为获得优良的紫花针茅内生细菌菌株并探究其生物功能,同时丰富高寒地区生防菌资源。【方法】采用传统微生物分离培养法,从东祁连山高寒草地紫花针茅体内分离得到一株内生细菌263ZY2,对其抑菌、分泌吲朵乙酸(IAA)、固氮和溶磷能力进行了测定,并通过16S rDNA序列分析及对形态学特征进行了鉴定。【结果】菌株263ZY2对马铃薯坏疽病菌Phoma foveata、枯萎病菌Fusarium avenaceum和炭疽病菌Colletotrichum coccodes的拮抗能力均在60%以上,且具有良好的固氮能力;在含和不含色氨酸的King氏培养基中分泌IAA的量分别为10.07 mg/L和12.32 mg/L;在PKO培养基中有明显的溶磷效果,其溶磷能力达13.46 mg/L;在NA培养基平板上,菌落大小为2 mm,圆形,边缘整齐,表面光滑,干燥,中间隆起,呈奶白色,菌体杆状,大小为1.45×0.38~3.85×0.78μm,革兰氏阳性。16S rDNA序列在GenBank中登录号为KF831365.1。【结论】结合形态特征和16S rDNA基因序列同源性分析,将263ZY2鉴定为枯草芽孢杆菌(Bacillus subtilis),且其具有良好的抑菌、固氮、溶磷和分泌IAA能力。

【Objective】The study was made to obtain excellent endophytic bacteria strains of Stipa purpurea and explore their biological functions,and to enrich biocontrol bacteria resources in alpine areas.【Method】Endophytic bacterial strain which named 263ZY2 was isolated from Stipa purpurea in alpine grassland in Eastern Qilian Moun⁃tains by using traditional microbial culture method.Its functions of anti⁃pathogenic fungi,secretion of IAA,nitrogen⁃fixing and phosphate⁃solubility were tested.The identification was made by 16S rDNA sequence analysis and morpho⁃logical characteristics.【Result】The result showed that 263ZY2 inhibited Phoma foveata,Fusarium avenaceum and Colletotrichum coccodes,and the inhibition rates were all above 60%.Besides,263ZY2 also possessed strong abili⁃ties of nitrogen fixation.In the medium containing tryptophan or not,secretion of IAA by 263ZY2 was 10.07 mg/L and 12.32 mg/L respectively.Strain 263ZY2 had obvious phosphorus dissolving effect in PKO medium,and its phos⁃phorus dissolving ability reached 13.46 mg/L.When strain 263ZY2 was placed on NA medium plate,the colony size was 2 mm,round,the edges were neat,the surface was smooth,dry,the middle was raised,the cell was milky white,the cell was rod shaped,the size was 1.45×0.38~3.85×0.78μm,and the strain was Gram positive.The 16S rDNA sequence had the entry number KF831365 in GenBank.【Conclusion】Based on morphological characteristics and sequence homology analysis of 16S rDNA,263ZY2 has been identified as Bacillus subtilis.It has good bacterio⁃stasis,nitrogen fixation,phosphorus solubility and IAA secretion ability.