一株色季拉山长鞭红景天根际溶磷菌的分离、鉴定及其低温适应性分析

[目的]从西藏色季拉山长鞭红景天根际土壤中分离筛选出溶磷菌株,为高寒植物根际促生菌的开发利用和丰富溶磷菌种质资源提供理论基础和科学依据.[方法]以长鞭红景天为研究物种,采用溶磷圈法从其根际土壤中分离溶磷菌,以钼锑抗比色法测定溶磷量进行复筛;筛选出溶磷效果最好的菌株,测定其产吲哚乙酸(IAA)、固氮促生特性,结合形态、生理生化特性和16S rRNA序列分析进行分类鉴定.以芽孢杆菌为对照,将芽孢杆菌和分离获得的溶磷菌株分别在4、10、15、20和30 ℃下培养7 d,研究其低温适应性.[结果]从长鞭红景天根际土壤中筛选出21株具有溶磷作用的菌株,其中PSB19菌株在PKO无机磷培养基上的溶磷圈直径/菌落直径(D/d)最高,液体溶磷量达392.15 μg/mL,具有产IAA和固氮特性,其在4和10℃的低温条件下生长良好.通过形态、生理生化鉴定和16S rDNA序列分析,将PSB19菌株归类于粘着箭菌(Ensifer adhaerens).[结论]PSB19菌株有较好的溶磷、产IAA和固氮特性及低温适应性,具有作为生物菌肥在农业生产及植被恢复等方面应用的潜力.

Isolation,identification and low temperature adaptation of a phosphorus solubilizing bacteria from rhizosphere soil of Rhodiola fastigiata in Sehgyla Mountains

[Objective]The strains with sound phosphate solubilizing capacity were isolated from rhizosphere soil of Rhodiola fastigiata in Sehgyla Mountains in Tibet,and their taxonomic status,growth promoting effects and low tempera-ture adaptation were introduced to provide theoretical basis and reference for developing growth promotion rhizobacteria of psychrophytes and enriching phosphate solubilizing strain resources.[Method]R.fastigiata was research species.Phos-phate solubilizing ring method was applied to isolate phosphate solubilizing bacteria,and the method of Mo-Sb colorime-try was applied to measure phosphorus solubilizing capacity.The strains with the optimum phosphorus solubilizing capaci-ty were selected,and their abilities of indoleacetic acid(IAA)production,nitrogen fixation and growth promotion were evaluated.These strains were graded based on morphology,physiological-biochemical characteristics and 16S rRNA gene sequence.Bacillus subtilis was used as control.B.subtilis and the strains isolated were cultured at 4,10,15,20 and 30℃for 7 d to study their low temperature adaptability.[Result]From the rhizosphere soil of Rhodiola fastigiata,21 bacterial strains with inorganic phosphate solubilizing capacity were selected.Phosphate solubilizing diameter/colony diameter(D/d) value of PSB19 was the highest in PKO liquid culture medium,and soluble phosphorus content reached 392.15 mg/L. PSB19 had ability of IAA secretion,nitrogen fixation,and grew well under low temperature(4 and 10℃). Through mor-phology,physiology and biochemistry identification and 16S rDNA sequence analysis,strain PSB19 was classified as En-sifer adhaerens.[Conclusion]Strain PSB19 has sound phosphate solubilizing capacity,IAA production,nitrogen fixation and low temperature adaptation.Therefore,it might act as a biological bacterial fertilizer for the application in agricultural production and revegetation.