摘要:盐地碱蓬作为生物改良盐碱地的理想材料，其根际土壤微生物对土壤改良发挥着重要作用。为了深入探索环渤海滨海盐碱地碱蓬根际土壤细菌群落结构组成及其功能，采用Illumina Misep高通量测序平台对环渤海地区滨海盐碱地盐地碱蓬根际土壤和裸地土壤进行测序。从16个样本中获得有效序列734 792条，4 285个OTUs，归属于41门、100纲、282目、400科、892属、1 577种。盐地碱蓬根际土壤细菌群落由变形菌门（Proteobacteria）、放线菌门（Actinobacteria）、绿弯曲门（Chloroflexi）、拟杆菌门（Bacteroidetes）、芽单胞菌门（Gemmatimonadetes）、酸杆菌门（Acidobacteria）、厚壁菌门（Firmicutes）、蓝藻细菌门（Cyanobacteria）、髌骨细菌门（Patescibacteria、浮霉菌门（Planctomycetes）组成。Alpha多样性计算结果表明，盐地碱蓬根际土壤细菌群落结构多样性高并与裸地土壤间差异显著；LEfSe（LDA Effect Size）分析发现，盐地碱蓬与裸地差异指示种明显不同。PCoA与相关性Heatmap表明，盐地碱蓬、速效氮、速效钾、速效磷、电导率是影响土壤细菌目类水平群落组成的主要因子。PICRUSt（Phylogenetic Investigation of Communities by Reconstruction of Unobserved States）分析表明微生物群落在新陈代谢等40个功能方面盐地碱蓬根际土壤比裸地土壤高。本研究表明盐地碱蓬覆盖能够降低土壤盐分，增加土壤养分，对土壤细菌群落多样性及其功能有积极作用。
Abstract:Suaeda salsa is an ideal agent for the biological enrichment of saline-alkali soil. Microorganisms in the rhizosphere of this plant play an essential role in soil improvement. The Illumina Misep high-throughput sequencing platform was used to explore the structural composition and function of the bacterial community in the rhizosphere soil of S. salsa and bare soil from coastal saline-alkali land in the Bohai Bay Rim area of Hebei, Shandong, and Tianjin, China. In total, 734 792 effective sequences were obtained from 16 samples, of which 4 285 OUTs belonged to 41 phyla, 100 classes, 282 orders, 400 families, 892 genera, and 1 577 species. The bacterial community in the rhizosphere soil of S. salsa contained Proteobacteria, Actinobacteria, Chloroflexi, Bacteroidetes, Gemmatimonadetes, Acidobacteria, Firmicutes, Cyanobacteria, Patescibacteria, and Planctomycetes. These results were consistent with the Alpha diversity analysis results, indicating that the community was highly diversified and significantly different from that of the bare soil. The LEfSe (LDA Effect Size) analysis showed that indicator species differentially occurred in S. salsa and bare soils. In S. salsa soil, Cyanobacteria, Acidobacteria, Alphaproteobacteria, Oxyphotobacteria, Chloroflexi, Rhizobiales, Nostocales, Sphingomonadales, Sphingomonadaceae, and Bacillus were the indicator species. Based on principal coordinates analyses and a correlation heatmap, the main factors affecting the soil bacterial community at order level were the presence of S. salsa, alkali-hydrolyzable nitrogen, available potassium, available phosphorus, and electrical conductivity. Also, Ectothiorhodospira and Balneolaceae could survive in bare soil with poor fertility, high salinity, and a viscous structure. PICRUSt (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States) analysis showed that 304 metabolic pathways at pathway level 3 were active in both soil, of which 41 pathways, especially those involving in metabolism were different between S. salsa soil and bare land soil. These results indicated that S. salsa growth has a positive effect on the diversity and function of soil bacterial community by improving soil structure and increasing nutrients levels. These findings may be applied to improve saline-alkali land, optimize soil environment, and enhance its usefulness and sustainability.
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