新疆典型盐碱生境可培养细菌多样性及特色菌株资源挖掘

Culturable bacterial diversity and characteristic strains from saline-alkaline environments in Xinjiang

摘要:

目的 新疆盐碱生境蕴藏着丰富且独特的微生物资源，为系统挖掘新疆典型盐碱环境的可培养微生物资源，揭示其多样性及潜在应用价值，本研究对巴里坤湖、艾丁湖等7个不同盐碱生境开展了系统性分离培养。方法 采集盐湖沉积物和盐碱土样品，选用13种差异化培养基，通过梯度稀释涂布法进行菌株分离。结合16S rRNA基因序列测定、系统发育树构建及多条件培养实验，分析菌株的物种组成、培养基筛选效果、盐度适应性，并进一步解析潜在新物种、厌氧菌株及高产胞外多糖(exopolysaccharide, EPS)菌株。结果 共分离获得935株细菌菌株资源，归属于4门8纲25目54科125属310种，其中包括20株(15种)潜在新物种。本研究中，芽孢杆菌门(Bacillota)、假单胞菌门(Pseudomonadota)和放线菌门(Actinomycetota)为优势可培养类群。此外，本研究还获得52株(20种)厌氧细菌，这些厌氧菌株主要分布于盐单胞菌属(Halomonas)。不同培养基和盐度对纯培养微生物类群的影响较为明显：R2A培养基筛选到的物种数最多，共108种；在不添加盐胁迫(0 NaCl)时芽孢杆菌属(Bacillus)为主要类群；在中度盐胁迫(5% NaCl)条件下，海杆菌属(Marinobacter)为重要类群之一；无论是在低盐(0 NaCl)、中盐(5% NaCl)还是高盐(10% NaCl)条件下，Halomonas始终是优势类群。为获得具有极强抗逆性能的功能菌株，本研究进一步通过高盐高碱条件筛选，最终获得15株具有产胞外多糖能力的菌株，其中，棕沙居海杆状菌(Marivirga harenae) EGI S10258和南极嗜碱盐单胞菌(Halomonas alkaliantarctica) EGI S10283产量最高，可达4.5 g/L。结论 新疆盐碱生境蕴藏丰富的可培养微生物资源，采用盐度和培养基多策略组合的方法极大丰富了盐碱生境微生物资源。在此基础上，本研究成功获得一批潜在新物种及具特定功能的菌株，为其后续的系统分类、生态适应机制解析与资源开发利用提供了重要的菌种和数据支撑。

Abstract:

Objective The saline-alkaline habitats in Xinjiang harbor rich and unique microbial resources. This study employed the culture-dependent way to explore the culturable microbial resources and reveal their diversity and potential functions from seven different saline-alkaline habitats, including Barkol Lake and Aiding Lake in Xinjiang.Methods Soil and sediment samples were collected from the seven saline-alkaline habitats. Thirteen modified media were designed and used for strain isolation via the gradient dilution plating method. The 16S rRNA gene sequencing, phylogenetic analysis, and multi-condition culture were employed to analyze the taxonomic positions, suitable media, and salinity adaptability of the strains. Furthermore, potential novel taxa, anaerobic strains, and exopolysaccharide (EPS)-producing strains were screened.Results A total of 935 bacterial strains were isolated and identified as 310 species belonging to 125 genera, 54 families, 25 orders, 8 classes of 4 phyla, including 20 strains representing 15 potential novel taxa. The dominant culturable taxa were Bacillota, Pseudomonadota, and Actinomycetota. In addition, 52 strains (20 species) of anaerobic bacteria were obtained, with the genus Halomonas being dominant. The microbial resources varied significantly among different media, and R2A was the most effective medium, screening out 108 species. Bacillus was dominant under no salt stress (0 NaCl), and Marinobacter was one of the important genera under moderate salt stress (5% NaCl). However, the genus Halomonas kept being dominant under low-salt (0 NaCl), moderate-salt (5% NaCl), or high-salt (10% NaCl) stress. To obtain the functional strains with extremely strong stress resistance, we screened 15 EPS-producing strains under high-salt and high-alkali conditions. Among them, Marivirga harenae EGI S10258 and Halomonas alkaliantarctica EGI S10283 showed the highest EPS titer, which reached 4.5 g/L.Conclusion The saline-alkaline habitats in Xinjiang were rich with culturable microbial resources. The application of a multi-condition culture approach significantly enhances the depth and breadth of microbial resource exploration. This study provides important microbial resources and data support for subsequent research on systematic taxonomy, ecological adaptation mechanisms, and resource utilization by getting potential novel species and functional strains.