一种耐铀植物促生菌的筛选及促生特性研究

Isolation and Identification of a Uranium-resistant Strain and Effect of Its Characteristics on Growth Promoting

采用富集培养法和LB平板法从铀尾矿污染区蓼科植物酸模根部中筛选和分离一株具有较强铀耐受能力的细菌菌株,通过特征反应和平均吸光度法分析其生长特性和不同培养条件下植物促生特性。结果表明:该菌株可在铀浓度350 mg/kg(土)条件下生长。具有较强的分泌IAA能力,普通条件下24 h产IAA 40.21 mg/L,最佳产IAA条件为温度为35℃,pH 7,转速为150 r/min,氮源为酵母膏,碳源为甘油;兼具ACC脱氨能力,普通条件下24 h产ACC酶活为0.32 U/μg,最佳的ACC酶活条件为温度为30℃,pH 7,转速180 r/min。结合形态学特征,生理生化初步特征和16s rDNA序列确定菌株为木糖氧化无色杆菌。不同铀浓度的盆栽实验接种该菌种能使苜蓿干重分别提高17.9%-110.4%;对铀的富集率分别提高12.2%-180.6%。

A uranium-resistant and plant growth-promoting bacterial strain was isolated from the root of a native Rumex acetosa in a uranium mining by enrichment culture and LB plate.Its growth characteristics and the performance of plant growth-promoting under different experimental conditions were analyzed by characteristic reaction and average absorbance method.The results showed that the strain grew well at the uranium concentration of 350 mg/kg,it produced indole-3-acetic acid(IAA)and IAA reached 40.21 mg/L in 24 h at normal condition.The optimal condition for IAA production was the temperature 30℃,pH 7,rotating speed 150 r/min,yeast extract as nitrogen source,and glycerol as carbon source.The strain also had deaminase capacity of ACC,and ACC enzymatic activity was 0.32 U/μg for 24 h at normal condition.The optimal condition for ACC enzyme activity was temperature 35℃,pH 7,and rotating speed 180 r/min.The strain was identified as Achromobacter xylosoxidans while combined morphological characteristic with physiological and biochemical preliminary characteristics and 16s rDNA sequence.Dry biomass of Medicago sativa increased by 17.9%-110.4%and U was enriched by 12.2%-180.6%under different U concentration.