基于可培养法分析亚热带植物内生与根际芽胞杆菌种类分布异质性

Distribution heterogeneity of Bacillus-like species in endophyte and rhizosphere of subtropical crops based on culturable method

摘要:

【背景】芽胞杆菌是农业上重要的微生物菌剂，对植物具有促生、防病、防虫等作用。【目的】了解亚热带植物内生和根际芽胞杆菌的种群分布，为其功能挖掘提供科学依据。【方法】采用可培养手段对甘蔗(Saccharum officinarum)、红麻(Hibiscus cannabinus L.)、黄麻(Corchorus capsularis L.)、黄秋葵(Abelmoschus esculentus)和玫瑰茄(Hibiscus sabdariffa)根际土壤和根内生芽胞杆菌进行分离，利用16S rRNA基因测序对分离菌株进行分类鉴定，并分析系统发育地位。【结果】共获得了可培养芽胞杆菌菌株144株，其中根内生芽胞杆菌82株，根际土壤62株。经16S rRNA基因测序鉴定为芽胞杆菌4个属37个种，分别为芽胞杆菌属、短芽胞杆菌属、类芽胞杆菌属和赖氨酸芽胞杆菌属。芽胞杆菌菌落数量和种类在根部及其根际土壤中差异较大，根际土壤中芽胞杆菌菌落数量远远大于根部，根际土壤中芽胞杆菌菌落含量范围为(0.2?370.0)×105 CFU/g，而根部为 (0.1?81.0)×103 CFU/g。根部分离获得的芽胞杆菌种类远大于根际土壤中，从作物根际土壤中共获得了芽胞杆菌19个种，从根部获得内生芽胞杆菌共32个种。阿氏芽胞杆菌(Bacillus aryabhattai)、仙草芽胞杆菌(Bacillus mesonae)和假蕈状芽胞杆菌(Bacillus pseudomycoides)同时存在于4种作物的根际土壤和根部，其他芽胞杆菌种类仅存在于1种作物的根际或者根部。【结论】亚热带作物根际土壤和根部芽胞杆菌种类和数量极为丰富，而且还存在可分离培养的芽胞杆菌潜在新物种，这为了解植物与根际微生物相互作用、根际环境生态平衡提供了理论基础和科学依据。

Abstract:

[Background] Bacilllus-like species are important microbial inoculants in agriculture to promote plant growth, prevent disease and insect. [Objective] To study Bacillus-like species community of several subtropical plant endophyte and rhizosphere soil, providing scientific foundation for mining Bacillus-like species. [Methods] On the basis of the culturable method, Bacillus-like species were isolated from roots and rhizosphere soil samples of Saccharum officinarum, Hibiscus cannabinus L., Corchorus capsularis L., Abelmoschus esculentus, and Hibiscus sabdariffa. Then, the isolates were identified by 16S rRNA gene and phylogenetic tree was constructed to explore the relationship between isolates and their related type species. [Results] There were 144 isolates obtained, including 82 isolates of endophytic bacteria and 62 isolates of rhizosphere bacteria, which were identified as 37 species of 4 genera, including Bacillus, Brevibacillus, Lysinibacillus, and Paenibacillus through 16S rRNA gene sequencing. The dominant genus was Bacillus, and the second one was Paenibacillus. There was great difference of the species number and colonies content in the root and rhizosphere soil. The colonies content in the rhizosphere was greater than roots. The colonies content range of Bacillus-like species in rhizosphere was (0.2?370.0)×105 CFU/g, but (0.1?81.0)×103 CFU/g in the root. Species number in roots was much larger than rhizosphere, which 19 species were obtained from rhizosphere and 32 were from roots. Bacillus aryabhattai, Bacillus mesonae and Bacillus pseudomycoides were both distributed in the 4 crop’s roots and rhizosphere, other species only occurred in the one crop’s roots or rhizosphere. [Conclusion] there were rich Bacillus-like species number and abundant content in the crop’s rhizosphere and roots, and several culturable potential novel Bacillus species, providing the theoretical base and scientific foundation for interaction of plant-microbe and ecological balance of rhizosphere environment.