西双版纳保护区植物根际细菌的筛选及其促生能力研究

Screening of plant-growth promoting rhizosphere actinomycetes in Xishuangbanna Reserve

摘要:

【背景】西双版纳自然保护区具有丰富的生物多样性，而该区域植物根际细菌特别是放线菌及其促生能力相关报道较少。【目的】从西双版纳保护区根际土壤中筛选出植物根际促生菌，并检测其促生能力。【方法】采用5种不同培养基筛选出植物根际促生菌并通过16S rDNA序列分析进行分类学鉴定，运用Salkowski法测定菌株产IAA的能力，CAS法测定菌株产铁载体能力，钼锑抗显色法测定菌株的解磷能力，CMC-Na法测定菌株产纤维素酶能力和改良的Young法测定产淀粉酶能力，综合评价所得菌株的促生能力。【结果】从土样中分离纯化得到14株典型促生菌，经鉴定分别归属于链霉菌属(Streptomyces)、诺卡菌属(Nocardi)、杆菌属(Bacillus)、中华根瘤菌属(Ensifer)、中慢生根瘤菌属(Mesorhizobium)、固氮螺菌属(Azospirillum)和狭单胞菌属(Stenotrophomonas)。其中菌株B433产吲哚乙酸的能力在培养12 d时达到最大值9.23 mg/L；菌株B351、B453、B546这3株菌株产铁载体的能力较强，其Su>80%，最高可达86.67%，强度为+++++；菌株B541的解磷能力最强，磷酸根的浓度达到9.79 mg/L；菌株B442综合产纤维素酶能力最强为31.86 U/mL；菌株B412淀粉酶活力为16.07 U/mL。【结论】西双版纳保护区植物根际土壤促生细菌种类丰富，且具有较强的广谱促生能力，有潜在的开发价值，本研究可为此地的微生物资源开发提供可靠的菌株资源依据。

Abstract:

[Background] Xishuangbanna Nature Reserve is rich in biodiversity, but few reports about plant growth promoting rhizobacteria especially actinomycetes in this reserve are found. [Objective] Screen the plant growth promoting rhizobacteria in Xishuangbanna Nature Reserve and test their growth-promoting ability. [Methods] Plant growth-promoting rhizobacteria was selected by five types of medium and followed by taxonomic identification based on 16S rDNA sequence analysis. The ability of obtained strains to produce IAA, siderophores, dissolved phosphorus, cellulase, and amylase activities were determined by Salkowski method, CAS method, molybdenum anti-chromogenic method, CMC-Na method and improved Young method, respectively. [Results] Fourteen strains of growth-promoting rhizobacteria, were isolated and purified from soil samples and identified as Streptomyces, Nocardia, Bacillus, Ensifer, Mesorhizobium, Azospirillum and Stenotrophomonas. Among the 14 strains isolated, strain B433 had the maximum capacity of indole acetic acid (9.23 mg/L) at 12 d. The strains of B351, B453 and B546 had strong iron siderophore production capacity, where the Su value were all >80%, and the maximum was 86.67%, with a strength of +++++. Strain B541 showed the strongest phosphorus solubility, and the concentration of dissolved phosphate reached 9.79 mg/L. The comprehensive cellulase production capacity of strain B442 was 31.86 U/mL. The amylase activity of strain B412 was 16.07 U/mL. [Conclusion] The rhizosphere soil in Xishuangbanna Nature Reserve contained a variety of growth-promoting rhizobacteria with strong and broad spectrum growth-promoting ability, which is valuable for research and exploitation. This study provides reliable basis of bacterial strain resource for the development of microorganism resource in Xishuangbanna Nature Reserve.