一株野生大豆内生细菌YDX14菌株的分离、鉴定及促生效应研究

Isolation,Identification and Growth Promoting Effect of an Endophytic Bacteria YDX14 in Wild Soybean

为筛选具有促生效应的内生细菌资源,从野生大豆叶片中分离筛选出1株内生细菌菌株YDX14,采用形态学观察和分子生物学分析方法对该菌株进行鉴定;通过测定菌株溶磷能力、产IAA能力、产ACC脱氨酶能力等研究菌株的促生特性;通过水培促生试验测定菌株对小麦幼苗的促生作用,并采用单因素和正交试验确定菌株的最佳发酵条件。结果表明:YDX14菌落为白色圆形,表面粘稠有光泽,边缘整齐,呈杆状,大小为(2.0~3.2)μm×(0.9~1.2)μm,是一种有芽孢,有荚膜,有鞭毛的革兰氏阴性细菌,为普罗威登斯菌属(Providencia)菌株;菌株具有溶磷能力,溶磷量为46 mg·L^(-1);且具有产IAA能力,达到19.97 mg·L^(-1);ACC酶活性达到8.59μmol·mg^(-1)·h^(-1);菌株处理小麦10 d后,促生效果最显著,株高、根长、叶干重与根干重分别增加了58.46%、81.89%、54.87%和29.9%;可溶性糖和可溶性蛋白含量均高于对照;其最佳发酵条件是以牛肉膏蛋白胨培养基为基础,葡萄糖1%、酵母膏1%、氯化钙2%、磷酸二氢钾0.1%,pH5.0。

To screen endophytic bacteria resources with growth-promoting effect,an endophytic bacterial strain YDX14 was isolated from wild soybean(Glycine soja)leaves and identified by morphological observation and molecular biological analysis.The growth-promoting characteristics of the strain were studied by measuring the ability to dissolve phosphorus,producing IAA,and producing ACC deaminase.The growth-promoting effect of strain on wheat seedlings was determined by hydroponic growth-promoting test,and the optimum fermentation conditions of strain were determined by a single factor experiment and orthogonal experiment.The results showed that YDX14 colony was white and round,with a sticky and shiny surface,neat edge and rod shape,and its size was(2.0-3.2)μm×(0.9-1.2)μm.It was a gram-negative bacterium with spores,capsules,and flagella,belonging to Providencia.The strain had the ability to dissolve phosphorus,and the amount of dissolving phosphorus was 46 mg·L^(-1).The IAA production capacity reached 19.97 mg·L^(-1).The ACC enzyme activity reached 8.59μmol·mg^(-1)·h^(-1).After 10 days of wheat treatment,the growth-promoting effect was the most significant,and the plant height,root length,leaf and root dry weight increased by 58.46%,81.89%,54.87%and 29.9%respectively.The contents of soluble sugar and soluble protein were higher than those of control.The optimum fermentation conditions were based on beef paste peptone medium,glucose 1%,yeast extract 1%,calcium chloride 2%,potassium dihydrogen phosphate 0.1%,and pH5.0.