摘要： 为鉴定从滨海盐土中分离的2株自生固氮菌，并探讨其环境适应性及小麦盆栽接种效应。采用形态特征、生理生化测定和16S rDNA基因序列分析的方法研究了2株菌的分类地位，采用乙炔还原法测定其固氮酶活性，用IAA分泌量表征环境适应性，利用小麦盆栽试验评价其对小麦幼苗的促生作用。初步鉴定菌株1为争论贪噬菌，菌株2为玉米固氮螺菌，固氮酶活性分别为4.71，2.84 μmol/（h·mL）。菌株1、2对酸碱度具有较强的适应性。渗透压结果显示，菌1、2在5% NaCl及以下浓度，IAA分泌能力较强。菌株1对甘露醇利用效果较好，菌株2对葡萄糖利用效果最好。外源低浓度NH₄⁺提高菌株1分泌IAA能力，当NH₄⁺浓度> 0.5 mmol/L，其分泌IAA能力受到不同程度抑制。菌株2对NH₄⁺利用呈M型曲线。盆栽试验表明，菌株1、2显著提高小麦株高、地上部干质量，促进小麦氮、磷、钾吸收，提高了土壤速效养分含量。土壤脲酶活性增加了16.00%，48.15%，其中菌株2效果最佳。菌株1、2具有较高的固氮酶活性、较强的环境适应性，小麦盆栽接种效果良好，属于高效固氮耐盐菌株，可为新垦低产盐碱农田的培肥使用，并可为中高产盐碱农田优化施肥结构提供技术支撑。

关键词: 滨海盐土, 自生固氮菌, 固氮酶活性, 生长素, 土壤脲酶, 16S rDNA

Abstract: In order to identify two strains of azotobacter isolated from coastal saline soil, explore the environmental adaptability of two strains and inoculated effect by pot experiment in wheat. Morphological observation, physiological and biochemical determination and 16S rDNA sequence identification were carried out. We also studied environmental adaptability of bacteria by the analysis of IAA and effect of wheat seedlings was evaluated by pot experiment in wheat.The characteristic of morphology and 16S rDNA sequence analysis revealed that strain 1 was classified as Variovorax paradoxus. And strain 2 was identified as Azospirillum zeae. The nitrogenase activity of strain 1 and strain 2 were 4.71 and 2.84 μmol/ (h·mL). The analysis of IAA indicated that both of two strains had strong ability to keep themselves under acid or alkalinity. The two strains had strong ability of IAA under 5% concentration of NaCl concentration. The strain 1 utilized mannitol most and the IAA amount of strain 2 was significantly higher under glucose. The results of strains secreted IAA under exogenous NH₄⁺ showed that low concentration of NH₄⁺ stimulate the strain 1 to secrete IAA.When the concentration of NH₄⁺ was over 0.5 mmol/L, IAA was inhibited in different degrees. The curve of strain 2 showed a M curve. Pot experiments showed that strain 1 and strain 2 significantly increased height and dry weight of wheat shoots, promoted the absorption of nitrogen, phosphorus and potassium in wheat, and improved the content of available nutrients in soil.The soil urease activity of two strains increased by 16.00% and 48.15%, and the strain 2 had the best effect. The two strains have high nitrogenase activity and strong adaptability. The treatments of two strains have good effect on the growth of wheat. The results can be used for the cultivation of new low yield saline alkali soil and provide technical support for optimizing the fertilization structure of medium and high yield saline alkali farmland.

Key words: Coastal saline soil, Abiogenous azotobacter, Nitrogenase activity, Auxin, Soil urease, 16S rDNA

中图分类号: 

• S154.1