水分驱动半干旱区河流沉积物/土壤厌氧绳菌群落的空间异质性

Moisture determined spatial heterogeneity of river sediment/soil Anaerolineaceae communities in semiarid region

摘要:

【背景】厌氧绳菌纲、目、科及属是海洋沉积物和湿地土壤中优势的微生物类群，但关于特定水分梯度下河流沉积物/土壤厌氧绳菌群落是否存在空间异质性及核心环境驱动力等问题尚不明晰。【目的】阐明蒙古高原半干旱区河流系统水生、湿生、旱生环境梯度下厌氧绳菌群落的空间异质性及环境驱动力，探明干旱胁迫下萎缩型河流湿地复湿过程中厌氧绳菌群落的指示作用。【方法】利用16S rRNA基因高通量测序及相关性和变异权重分析等方法研究河流系统水分梯度下沉积物/土壤厌氧绳菌群落不同种群的组成、丰度、分布及其环境驱动力。【结果】厌氧绳菌群落15个种群主要分布在水生及湿生环境，由水分、氨氮、砂粒及pH正向驱动，由盐度、全氮、全磷、粉粒和黏粒等负向驱动(uncultured_us15由砂粒和氨氮负向驱动及粉粒和盐度正向驱动除外)；9个和6个厌氧绳菌种群分别由总有机碳正向和负向驱动。变异权重分析表明水分、氨氮、盐度、有机碳、pH分别解释了厌氧绳菌群落空间变异的64.8%、8.9%、7.5%、2.2%、1.7%。【结论】蒙古高原半干旱区厌氧绳菌群落存在明显的空间异质性，偏好高水砂、高氨、高pH等水生和湿生环境，不耐受盐度和营养偏高的旱生环境，由水分核心驱动，可能为自养异养混合的游离型氨氧化细菌，是干旱胁迫下萎缩型河流湿地水分恢复过程的重要指示生物。

Abstract:

[Background] The members of Anaerolineaceae family (e.g., Anaerolinea genus) from Anaerolineales order of Anaerolineae class are mainly distributed in marine sediments and wetland soils. However, little is known about the spatial heterogeneity of sediments/soils Anaerolineaceae communities and environmental drivers under a specific moisture gradient. [Objective] To elucidate the spatial heterogeneity of Anaerolineaceae communities and core environmental drivers under the moisture gradient along aquatic, hygrophic and xerophytic environments in river system from semiarid region of Mongolian Plateau, and deciphering the early predicting function of Anaerolineaceae communities during the rewetting process of drought-induced shrinking river wetland. [Methods] High-throughput sequencing of 16S rRNA gene, Pearson correlation and variation partitioning analyses were employed to detect the compositions, abundance, spatial distribution of sediment/soil different populations in Anaerolineaceae communities and environmental drivers under the moisture gradient. [Results] The 15 populations of Anaerolineaceae communities were mainly distributed in the aquatic, hygrophic environments, which were positively driven by moisture, pH, sand and ammonia nitrogen, while negatively driven by salinity, total nitrogen and total phosphorus, silt and clay particles. Exceptionally, Uncultured_us15 population was negatively driven by sand and ammonia while positively driven by silt and salinity. Interestingly, 9 and 6 populations in Anaerolineaceae communities showed positive and negative correlation with total organic carbon, respectively. Variation partitioning analysis showed that moisture, ammonia, salinity, organic carbon and pH explained the spatial variation of Anaerolineaceae communities with 64.8%, 8.9%, 7.5%, 2.2% and 1.7%, respectively. [Conclusion] Anaerolineaceae communities demonstrated obvious spatial heterogeneity, which preferred to aquatic and hygrophic environments with high moisture, sand, ammonia and high pH rather than xerophytic environments with relatively rich salinity and nutrition from semiarid region of Mongolia Plateau. The spatial heterogeneity of Anaerolineaceae communities was mainly driven by moisture. Anaerolineaceae communities were key indicators predicting the rewetting process of drought-induced shrinking river wetland, which were probably autotrophic or heterotrophic ammonia-oxidizing bacteria.