Table 2_Taxonomic and functional diversity of alkali-tolerant bacteria enriched from the Taklimakan Desert.xlsx

The Taklimakan Desert is a naturally alkaline ecosystem harboring a rich diversity of alkali-resistant microorganisms. However, systematic studies on their distribution, diversity, and biotechnological potential remain limited. In this study, five representative soil samples were collected from the central region of the Taklimakan Desert, where the original soil pH ranged from 8.78 to 9.8. To investigate the effect of alkaline conditions on microbial communities, the samples were subjected to enrichment in culture media adjusted to pH 9–11. The bacterial community structure of the enriched fraction was assessed using culture-independent 16S rRNA gene amplicon sequencing, while a non-enriched control (CK) group—consisting of the same soils without pH adjustment—was simultaneously sequenced to determine the baseline bacterial composition. In parallel, a culture-dependent approach was employed to isolate alkali-tolerant bacterial strains from the same samples using Gibbons medium at pH 9, 10, and 11. Based on distinct colony morphologies, isolates were selected, repeatedly purified by streaking, and taxonomically identified via 16S rRNA gene sequencing, resulting in a total of 291 strains. These isolates were taxonomically assigned to four phyla, six classes, 17 orders, 25 families, and 56 genera. Among them, 114 strains shared less than 98.65% sequence identity with known species, suggesting the presence of numerous potential novel taxa. Approximately 14.07 and 61.48% of the isolates were categorized as alkali-tolerant and alkalophilic, respectively, with 85 strains capable of growing under extreme conditions (pH 12 and/or 25% salinity). Functional screening revealed enzymatic activity in a substantial portion of the isolates: 20.35% produced amylase, 19.91% protease, 30.30% cellulase, and 47.61% exhibited at least one enzymatic function. Overall, this study integrates both culture-independent and culture-dependent approaches to reveal the taxonomic and functional diversity of alkali-tolerant bacteria in the Taklimakan Desert, highlighting their ecological roles and potential applications in industrial biotechnology.

塔克拉玛干沙漠是天然碱性生态系统，孕育着丰富的耐碱微生物（alkali-resistant microorganisms）多样性，但目前针对其分布、多样性及生物技术潜力的系统性研究仍较为有限。本研究从塔克拉玛干沙漠中部区域采集了5份代表性土壤样本，其原始土壤pH值介于8.78至9.8之间。为探究碱性条件对微生物群落的影响，研究人员将样本置于pH调节至9~11的培养基中进行富集培养；对富集组分，采用不依赖培养的16S rRNA基因扩增子测序（culture-independent 16S rRNA gene amplicon sequencing）解析其细菌群落结构；同时设置未富集的对照组（CK组），即未经pH调节的原土壤样本，同步进行测序以解析基线细菌群落组成。与此同时，本研究采用依赖培养的（culture-dependent）方法，使用pH分别为9、10、11的Gibbons培养基，从相同土壤样本中分离耐碱细菌菌株。研究人员依据菌落形态差异挑选分离株，通过划线法反复纯化，并借助16S rRNA基因测序（16S rRNA gene sequencing）完成分类学鉴定，最终共获得291株菌株。这些分离株经分类学归属，隶属于4个门、6个纲、17个目、25个科以及56个属。其中114株菌株与已知物种的序列同源性低于98.65%，表明存在大量潜在的新分类单元。约14.07%和61.48%的分离株分别被归类为耐碱菌和嗜碱菌（alkalophilic），另有85株菌株可在极端条件（pH 12和/或25%盐度（salinity））下生长。功能筛选结果显示，多数分离株具有酶活性：20.35%的菌株可产生淀粉酶，19.91%可产生蛋白酶，30.30%可产生纤维素酶，47.61%的菌株至少具备一种酶功能。综上，本研究结合不依赖培养的与依赖培养的两种手段，揭示了塔克拉玛干沙漠中耐碱细菌的分类学与功能多样性，凸显了其生态作用及在工业生物技术领域的潜在应用价值。