内蒙古和海南干旱地区芽孢杆菌和伯克霍德尔菌的耐旱性

Drought tolerance of Bacillus spp. and Burkholderia spp. in arid areas of Inner Mongolia and Hainan

摘要:

【背景】 世界旱灾的频发对农作物的产量和品质都造成了严重的影响，亟需一种经济节约的方法来缓解。植物根际促生细菌有望直接用于农作物提高耐旱性。【目的】 干旱环境中的微生物物种组成和分布格局具有独特性。研究从干旱土壤中筛选出的细菌遗传多样性和功能多样性十分必要。【方法】 利用聚乙二醇6000 (polyethylene glycol 6000, PEG-6000)模拟干旱胁迫，对内蒙古和海南干旱地区采集分离获得的30份芽孢杆菌(Bacillus spp.)和伯克霍德尔菌(Burkholderia spp.)进行耐旱性分析及生物学特性分析。【结果】 通过聚类分析把30株供试菌株的耐旱能力分为三类群，并且不同胁迫条件下供试菌株表现为3种生长模式：在第一类生长模式中，渗透势-0.2 mPa与0 mPa的OD₆₀₀值无显著差异；第二类生长模式中，随着渗透势的增加，菌株的OD₆₀₀值也随之下降。这类菌占总体供试菌株的43.33%；第三类生长模式中，菌株在-0.6 mPa和-1.2 mPa渗透势下，OD₆₀₀值无显著差异。对30株供试菌株进行生物学特性分析，发现每株菌都有产吲哚乙酸(indole acetic acid, IAA)、铁载体、脲酶、精氨酸脱羧酶和生物膜这5种特性中的1-4种特性，即供试菌株都具有潜在的植物促生功能。【结论】 基于耐旱性分析和生物学特性分析，最终筛选到2株优质耐旱芽孢杆菌NC51、NO89，均为第三类生长模式。为今后提高作物耐旱性和研发微生物菌剂提供菌种资源。

Abstract:

[Background] The frequent occurrence of drought in the world has seriously affected both the yield and quality of crops. An economically efficient method to alleviate it is urgently needed. Plant growth-promoting rhizobacteria (PGPR) are expected to directly improve drought tolerance in crops. [Objective] In arid environments, the species composition and distribution patterns of microbial communities are unique. It is essential to study the genetic diversity and functional diversity of bacteria screened from arid soils. [Methods] Thirty strains of Bacillus spp. and Burkholderia spp. were collected and isolated from the arid areas in Inner Mongolia and Hainan provinces, respectively. These strains were subjected to drought tolerance analysis and biological characteristic analysis using polyethylene glycol 6000 (PEG-6000) to simulate drought stress. [Results] Cluster analysis categorized the drought tolerance of the 30 tested strains into 3 groups. The tested strains exhibited 3 growth patterns under different stress conditions: in the first type of growth pattern, there was no significant difference in OD₆₀₀ value between the permeability potential of -0.2 mPa and 0 mPa; in the second type of growth pattern, the OD₆₀₀ value of the strain decreased as permeability potential increased, and the strains which exhibited this growth pattern represent 43.33% of the total tested strains; in the third type of growth pattern, there was no significant difference in OD₆₀₀ values at -0.6 mPa and -1.2 mPa permeation potential. The biological characteristics of the 30 tested strains revealed that each strain exhibited 1 to 4 characteristics of IAA, siderophore, urease, arginine decarboxylase, and biofilm, indicating the tested strains have potential plant growth-promoting functions. [Conclusion] Based on drought tolerance analysis and biological characteristic analysis, two superior drought resistance Bacillus strains, NC51 and NO89, were finally screened, both exhibiting the third type of growth pattern. These strains provide microbial resources for improving crop drought tolerance and developing microbial inoculants in the future.