College of Chemistry and Environmental Engineering, Chongqing Key Laboratory of Environmental Materials & Remediation Technologies, Chongqing University of Arts and Sciences, Chongqing, China.
Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau, School of Ecology and Environment, Inner Mongolia University, Hohhot, Inner Mongolia Autonomous Region, China.
PeerJ. 2023 Aug 21;11:e15909. doi: 10.7717/peerj.15909. eCollection 2023.
Alkaline lakes are a special aquatic ecosystem that act as important water and alkali resource in the arid-semiarid regions. The primary aim of the study is to explore how environmental factors affect community diversity and structure, and to find whether there are key microbes that can indicate changes in environmental factors in alkaline lakes. Therefore, four sediment samples (S1, S2, S3, and S4) were collected from Hamatai Lake which is an important alkali resource in Ordos' desert plateau of Inner Mongolia. Samples were collected along the salinity and alkalinity gradients and bacterial community compositions were investigated by Illumina Miseq sequencing. The results revealed that the diversity and richness of bacterial community decreased with increasing alkalinity (pH) and salinity, and bacterial community structure was obviously different for the relatively light alkaline and hyposaline samples (LAHO; pH < 8.5; salinity < 20‰) and high alkaline and hypersaline samples (HAHR; pH > 8.5; salinity > 20‰). Firmicutes, Proteobacteria and Bacteriodetes were observed to be the dominant phyla. Furthermore, Acidobacteria, Actinobacteria, and low salt-tolerant alkaliphilic nitrifying taxa were mainly distributed in S1 with LAHO characteristic. Firmicutes, Clostridia, Gammaproteobacteria, salt-tolerant alkaliphilic denitrifying taxa, haloalkaliphilic sulfur cycling taxa were mainly distributed in S2, S3 and S4, and were well adapted to haloalkaline conditions. Correlation analysis revealed that the community diversity (operational taxonomic unit numbers and/or Shannon index) and richness (Chao1) were significantly positively correlated with ammonium nitrogen (r = 0.654, < 0.05; r = 0.680, < 0.05) and negatively correlated with pH (r = -0.924, < 0.01; r = -0.800, < 0.01; r = -0.933, < 0.01) and salinity (r = -0.615, < 0.05; r = -0.647, < 0.05). A redundancy analysis and variation partitioning analysis revealed that pH (explanation degrees of 53.5%, pseudo-F = 11.5, < 0.01), TOC/TN (24.8%, pseudo-F = 10.3, < 0.05) and salinity (9.2%, pseudo-F = 9.5, < 0.05) were the most significant factors that caused the variations in bacterial community structure. The results suggested that alkalinity, nutrient salt and salinity jointly affect bacterial diversity and community structure, in which one taxon (Acidobacteria), six taxa (Cyanobacteria, Nitrosomonadaceae, , , and ) and five taxa (, , , and ) are related to carbon, nitrogen and sulfur cycles, respectively. Classes Clostridia and Gammaproteobacteria might indicate changes of saline-alkali conditions in the sediments of alkaline lakes in desert plateau.
碱性湖泊是一种特殊的水生生态系统，是干旱半干旱地区重要的水和碱资源。本研究的主要目的是探讨环境因素如何影响群落多样性和结构，并寻找是否存在能够指示碱性湖泊环境因素变化的关键微生物。因此，从内蒙古鄂尔多斯沙漠高原的重要碱资源哈马泰湖采集了四个沉积物样品（S1、S2、S3 和 S4）。样品沿盐度和碱度梯度采集，通过 Illumina Miseq 测序研究细菌群落组成。结果表明，随着碱度（pH）和盐度的增加，细菌群落的多样性和丰富度降低，细菌群落结构明显不同，对于相对较浅的碱性和低盐度样品（LAHO；pH<8.5；盐度<20‰）和高碱性和高盐度样品（HAHR；pH>8.5；盐度>20‰）。厚壁菌门、变形菌门和拟杆菌门被观察到是主要的门。此外，酸杆菌门、放线菌门和耐低盐碱性硝化类群主要分布在 S1 中，具有 LAHO 特征。Firmicutes、Clostridia、Gammaproteobacteria、耐盐碱性反硝化类群、卤代碱硫循环类群主要分布在 S2、S3 和 S4 中，能很好地适应卤代碱性条件。相关性分析表明，群落多样性（操作分类单元数和/或 Shannon 指数）和丰富度（Chao1）与铵氮（r=0.654， <0.05；r=0.680， <0.05）显著正相关，与 pH（r=-0.924， <0.01；r=-0.800， <0.01；r=-0.933， <0.01）和盐度（r=-0.615， <0.05；r=-0.647， <0.05）显著负相关。冗余分析和变异划分分析表明，pH（解释度 53.5%，伪 F=11.5， <0.01）、TOC/TN（24.8%，伪 F=10.3， <0.05）和盐度（9.2%，伪 F=9.5， <0.05）是导致细菌群落结构变化的最显著因素。结果表明，碱性、养分盐和盐度共同影响细菌多样性和群落结构，其中一个类群（酸杆菌门）、六个类群（蓝细菌门、、、和）和五个类群（、、、和）与碳、氮和硫循环有关。梭菌纲和γ-变形菌纲可能指示沙漠高原碱性湖泊沉积物中盐碱性条件的变化。
