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

ObjectiveThe 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.MethodR.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.ResultFrom 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.ConclusionStrain 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.