一株耐盐碱多黏类芽孢杆菌TaRb44的分离鉴定和耐盐促生作用评价

Isolation, identification, and plant growth-promoting effect evaluation of a saline-alkali-tolerant rhizobacterium Paenibacillus polymyxa TaRb44

摘要:

目的 为筛选获得具有良好耐盐碱能力的植物根际促生菌，并对其功能进行评价。方法 采集不同盐碱条件下的小麦根际土，通过耐盐碱富集和稀释涂布法分离高效耐盐碱细菌。利用平板对峙和选择性培养基检测菌株的抑菌和促生特性，并利用ELISA试剂盒检测菌株分泌的固氮酶活性。结合形态学、生理生化及系统进化分析鉴定其分类地位。通过室内盆栽人工模拟盐胁迫，探究菌株对小麦生长的影响。结果 从根际土壤中富集到一株丰度较高的耐盐碱细菌，命名为TaRb44，该菌株能够在3% NaCl和pH 10.0的条件下正常生长。菌株TaRb44对引起小麦茎基腐病的假禾谷镰孢菌、引起西瓜枯萎病的尖孢镰孢菌西瓜专化型、引起香蕉枯萎病的尖孢镰孢菌古巴专化型，以及引起番茄采后灰霉病的灰葡萄孢菌，均具有较强的拮抗作用。同时，该菌株还能产生嗜铁素、淀粉酶、纤维素酶等多种植物促生相关活性物质，并具有良好的生物固氮活性，其分泌的固氮酶含量为65.50 U/L。经系统鉴定，菌株TaRb44为多黏类芽孢杆菌(Paenibacillus polymyxa)。温室盆栽试验结果表明，经P. polymyxa TaRb44浸种处理后，在盐胁迫和非盐胁迫条件下均能显著促进小麦幼苗生长，增加根系生物量。结论 本研究获得了一株具有防病、促生、耐盐碱等多种优良性状的多黏类芽孢杆菌TaRb44，为今后开发新的微生物菌肥和土壤改良剂提供了良好的菌种资源。

关键词:耐盐碱;拮抗;促生;多黏类芽孢杆菌

Abstract:

Objective To screen and identify the plant growth-promoting bacterial strain with saline-alkali tolerance and evaluate its functions.Methods The rhizosphere soil of wheat was collected from different saline-alkali regions, and the highly efficient saline-alkali-tolerant bacterial strain was isolated by enrichment under saline-alkali condition and dilution coating. The antifungal spectrum and plant growth-promoting effects of the isolate were evaluated in vitro, and the nitrogenase activity was measured by an ELISA kit. The strain was identified based on the morphological, physiological, biochemical characteristics and phylogenetic analysis. The effect of the strain on wheat growth under salt stress was investigated by a pot experiment.Results A highly abundant bacterium with saline-alkali tolerance was enriched from rhizosphere soil and designated as TaRb44, which could grow normally under 3% NaCl and pH 10.0. Strain TaRb44 showed strong antagonism against soil-borne pathogenic fungi such as Fusarium pseudograminearum causing wheat crown rot, Fusarium oxysporum f. sp. niveum causing watermelon Fusarium wilt, and Fusarium oxysporum f. sp. cubense causing banana wilt, as well as Botrytis cinerea causing gray mold of postharvest tomatoes. Further tests showed that strain TaRb44 produced a variety of plant growth-promoting substances such as siderophores, amylase, and cellulase, and it had nitrogen fixation activity with the nitrogenase level of 65.50 U/L. Finally, the strain TaRb44 was identified as Paenibacillus polymyxa, which significantly promoted the growth of wheat seedlings and increased the root biomass under both salt stress and non-salt stress conditions.Conclusion In this study, P. polymyxa TaRb44 was obtained with much excellent properties such as disease prevention, plant growth promotion, and saline-alkali tolerance. It serves as an elite strain for developing new microbial fertilizer and soil amendments in the future.

Key words:saline-alkali tolerance;antagonism;plant growth-promoting;Paenibacillus polymyxa