Zhang Kaoping, Shi Yu, Cui Xiaoqing, Yue Ping, Li Kaihui, Liu Xuejun, Tripathi Binu M, Chu Haiyan
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China.
University of Chinese Academy of Sciences, Beijing, China.
mSystems. 2019 Feb 12;4(1). doi: 10.1128/mSystems.00225-18. eCollection 2019 Jan-Feb.
Soil salinization is a growing environmental problem caused by both natural and human activities. Excessive salinity in soil suppresses growth, decreases species diversity, and alters the community composition of plants; however, the effect of salinity on soil microbial communities is poorly understood. Here, we characterize the soil microbial community along a natural salinity gradient in Gurbantunggut Desert, Northwestern China. Microbial diversity linearly decreased with increases in salinity, and community dissimilarity significantly increased with salinity differences. Soil salinity showed a strong effect on microbial community dissimilarity, even after controlling for the effects of spatial distance and other environmental variables. Microbial phylotypes ( = 270) belonging to , , [], , and showed a high-salinity niche preference. Out of nine potential phenotypes predicted by BugBase, oxygen-related phenotypes showed a significant relationship with salinity content. To explore the community assembly processes, we used null models of within-community (nearest-taxon index [NTI]) and between-community (βNTI) phylogenetic composition. NTI showed a significantly negative relationship with salinity, suggesting that the microbial community was less phylogenetically clustered in more-saline soils. βNTI, the between-community analogue of NTI, showed that deterministic processes have overtaken stochastic processes across all sites, suggesting the importance of environmental filtering in microbial community assembly. Taken together, these results suggest the importance of salinity in soil microbial community composition and assembly processes in a desert ecosystem. Belowground microorganisms are indispensable components for nutrient cycling in desert ecosystems, and understanding how they respond to increased salinity is essential for managing and ameliorating salinization. Our sequence-based data revealed that microbial diversity decreased with increasing salinity, and certain salt-tolerant phylotypes and phenotypes showed a positive relationship with salinity. Using a null modeling approach to estimate microbial community assembly processes along a salinity gradient, we found that salinity imposed a strong selection pressure on the microbial community, which resulted in a dominance of deterministic processes. Studying microbial diversity and community assembly processes along salinity gradients is essential in understanding the fundamental ecological processes in desert ecosystems affected by salinization.
土壤盐渍化是一个由自然和人类活动共同导致的日益严重的环境问题。土壤中盐分过高会抑制植物生长、降低物种多样性并改变植物群落组成；然而，盐分对土壤微生物群落的影响却鲜为人知。在此，我们对中国西北部古尔班通古特沙漠中沿自然盐度梯度的土壤微生物群落进行了特征描述。微生物多样性随盐度增加呈线性下降，群落差异随盐度差异显著增加。即使在控制了空间距离和其他环境变量的影响之后，土壤盐度对微生物群落差异仍有强烈影响。属于[具体分类]的270种微生物系统型表现出对高盐度生态位的偏好。在BugBase预测的九种潜在表型中，与氧气相关的表型与盐分含量存在显著关系。为了探究群落组装过程，我们使用了群落内（最近分类单元指数[NTI]）和群落间（βNTI）系统发育组成的零模型。NTI与盐度呈显著负相关，表明在盐度较高的土壤中微生物群落的系统发育聚类程度较低。βNTI作为NTI的群落间类似物，表明在所有地点确定性过程已超过随机过程，这表明环境过滤在微生物群落组装中具有重要作用。综上所述，这些结果表明盐度在沙漠生态系统土壤微生物群落组成和组装过程中的重要性。地下微生物是沙漠生态系统养分循环中不可或缺的组成部分，了解它们如何应对盐度增加对于管理和改善盐渍化至关重要。我们基于序列的数据显示，微生物多样性随盐度增加而降低，某些耐盐系统型和表型与盐度呈正相关。使用零模型方法来估计沿盐度梯度的微生物群落组装过程，我们发现盐度对微生物群落施加了强大的选择压力，这导致确定性过程占主导地位。研究沿盐度梯度的微生物多样性和群落组装过程对于理解受盐渍化影响的沙漠生态系统的基本生态过程至关重要。
