KMS XINJIANG INSTITUTE OF ECOLOGY AND GEOGRAPHY，CAS
| 古尔班通古特沙漠生物结皮对氨氧化菌群差异分布的影响 | |
| Alternative Title | Effects of biological crusts on the differential distribution of ammonia-oxidizing microorganisms in Gurbantunggut Desert |
| 刘鑫 | |
| Subtype | 硕士 |
| Thesis Advisor | 荣晓莹 |
| 2020-09-30 | |
| Degree Grantor | 中国科学院大学 |
| Place of Conferral | 北京 |
| Degree Discipline | 工程硕士 |
| Keyword | 氨氧化菌群 生态位 荒漠土壤 潜在氨氧化速率 氮素转化 Ammonia-oxidizing microbes Niche Desert soil Potential ammonia oxidation rate Nitrogen transformation |
| Abstract | 生物土壤结皮（生物结皮） 是古尔班通古特沙漠地表的重要覆被类型，在荒漠生态系统的氮素循环中扮演重要角色，氨氧化过程是氮素循环的限速步骤， 目前， 我们仍不清楚荒漠生物结皮系统对沙漠土壤氨氧化微生物的作用。本研究利用荧光定量 PCR（fluorescent quantative PCR， qPCR）方法分析不同季节生物结皮覆盖与去除结皮不同土层（0-2， 2-5， 5-10 和 10-20 cm）氨氧化菌群丰度特征，利用高通量测序的方法分析结皮覆盖与去除结皮不同土层氨氧化古菌（ammoniaoxidizing archaea， AOA）的微生物群落结构，结合氨氧化速率和土壤理化参数，以期探究生物结皮对荒漠土壤氨氧化微生物的影响以及冻融期荒漠土壤氮素转化过程。我们分析发现氨氧化古菌是古尔班通古特沙漠土壤的优势氨氧化菌群。生物结皮显著抑制表层（0-2 cm）土壤 AOA 和 0-20 cm 层土壤 AOB（ammonia-oxidizingbacteria， AOB） amoA 基因的丰度（P < 0.05）。 AOA 在次表层（2-5 cm） 土壤中amoA 基因丰度最高（1.4×104 – 8.7×104 copies·g-1）， AOB 在去除结皮表层土壤中amoA 基因丰度最高（6.8×103 – 2.6×104 copies·g-1）。 AOA amoA 基因丰度在夏季（Summer） 显著增加（P < 0.05）， AOB amoA 基因丰度在冬季（Winter） 最高（P< 0.05）。冗余分析（redundancy analysis， RDA）结果显示土壤温度、全碳以及全氮含量、电导率、含水量和 pH 是影响荒漠生态系统氨氧化微生物 amoA 基因丰度最重要的环境因子。古尔班通古特沙漠土壤氨氧化古菌主要隶属于泉古菌门（Crenarchaeota）。荒漠生物结皮与结皮下层土壤 AOA 群落结构具有显著差异， 次表层土壤 AOA群落多样性显著高于表层土壤（P < 0.001）。 OTU61 是表层和次表层土壤 AOA群落优势氨氧化菌 OTU，生物结皮表层和次表层土壤该 OTU 相对丰度分别为75%和 40%。冻融期生物结皮覆盖显著降低表层土壤 AOA amoA 基因的丰度以及 0-20 cm层土壤 AOB amoA 基因丰度（P < 0.01），同时生物结皮显著增加 2-20 cm 层土壤AOA amoA 基因丰度（P < 0.05）。 荒漠土壤不同土层潜在氨氧化速率（Potentialammonia oxidation rate， PAR） 也具有显著差异（P < 0.001）。 结皮表层土壤 PAR显著大于去除结皮表层土壤 PAR（0.20 – 0.38 μg·N day-1·g-1 > 0.14 – 0.19 μg·N day-1·g-1）（P < 0.01），显示生物结皮对冻融期荒漠表层土壤氨氧化过程具有促进作用。 土壤全碳、全氮以及铵态氮含量、电导率和含水量是显著促进冻融期荒漠结皮土壤氨氧化过程的重要环境因子。冻融期荒漠土壤氨氧化古菌同其他季节主要属于泉古菌门（Crenarchaeota）。方差分析发现结皮覆盖与去除结皮处理对 AOA 群落结构没有显著影响， 表层土壤 AOA 多样性、丰富度以及均匀度显著低于次表层、下层以及深层土壤（P <0.05）。冻融期， 土壤氨氧化古菌主要属于泉古菌门（Crenarchaeota）。 结皮覆盖与去除结皮对土壤 AOA 的群落结构无显著影响，次表层、下层以及深层土壤 AOA的群落多样性、丰富度以及均匀度都显著高于表层土壤（P < 0.05）。表层土壤优势 AOA 菌群更偏好高水、高氮的富营养环境，而深层土壤优势 AOA 菌群与之相反，而且表层土壤优势 AOA 菌群可能更有利于促进氨氧化作用。综上所述， 我们认为生物结皮与去除结皮不同处理多种土壤环境因素协同作用，促使古尔班通古特沙漠氨氧化古菌和细菌随生物结皮垂直梯度以及不同季节差异分布，并耦合环境因子促使氨氧化菌群时间空间生态位分化和介导荒漠土壤的氨氧化过程。本研究为认识温带荒漠结皮系统的氮素转化提供基础依据。 |
| Other Abstract | Biological soil crust (Biocrust) is an important cover type on the surface of theGurbantunggut Desert, which fixed large amount of nitrogen in the desert and playsimportant roles in the nitrogen cycle of the desert ecosystem. The ammoxidation is therate-limiting step of nitrogen cycle, while little is known about effects of biocrust onammonia oxidation in the Gurbantunggut Desert. In this study, fluorescencequantitative PCR (qPCR) was used to quantify ammonia-oxidizing archaea (AOA) andammonia-oxidizing bacteria (AOB) amoA gene abundance in different depth (0-2, 2-5,5-10 and 10-20 cm) of Biocrust and Biocrust-removal soil from winter to summer.High-throughput sequencing of AOA, potential ammonia oxidation rate and soilphysical and chemical parameters were compiled to explore the effect of biocrust onthe ammonia-oxidizing microorganisms and process of nitrogen transformation indesert soil during freeze-thaw periods.The results suggested that the abundances of AOA (7.8×103 – 9.2×104 copies·g-1)in soil of Biocrusts and Biocrusts-removal (0–2, 2–5, 5–10, 10–20 cm) werepredominant over that (1.4×101 – 2.6×104 copies·g-1) of AOB (P < 0.001). Biocrustsignificantly inhibited the abundance of AOA amoA genes in surface soil and theabundance of AOB amoA genes in 0-20 cm soil (P < 0.05). The abundance of AOAamoA gene was the highest in subsurface soil (1.4×104 – 8.7×104 copies·g-1), and theabundance of AOB amoA gene was the highest in Biocrust-removal surface soil(6.8×103 – 2.6×104 copies·g-1). AOA amoA gene abundance increased significantly inSummer (P < 0.05), while AOB amoA gene abundance was the highest in Winter (P <0.05). Redundancy analyses (RDA) further indicated that soil temperature, total carbonand total nitrogen content, electrical conductivity, moisture, and pH were the mostimportant environmental factors that affect the abundance of the amoA gene ofammonia-oxidizing microorganisms in desert ecosystems.Ammonia-oxidizing archaea mainly belongs to Crenarchaeota in theGurbantunggut Desert. There were significant differences in AOA community structurebetween biocrust and subsurface soil in the Gurbantunggut Desert. The diversity ofAOA community in the subsurface soil of Biocrust was significantly higher than thatof surface soil (P < 0.001). OTU61 was the dominant OTU of AOA communities,accounting for about 75% and 40% of the relative abundance of AOA communities in surface and subsurface soils, respectively.During freeze-thaw periods, Biocrust significantly reduced the abundance of AOAin the surface soil and AOB in 0-20 cm depth, but Biocrust significantly increased theabundance of AOA in 2-20 cm depth. Potential ammonia oxidation rate (PAR) ofdifferent soil depths was significantly different in desert soil (P < 0.001). The PAR ofsurface soil of Biocrust was significantly higher than that of Biocrust-removal (0.20 –0.38 μg·N day-1·g-1 > 0.14 – 0.19 μg·N day-1·g-1) (P < 0.01). Biocrust can promote theammoxidation process of desert surface soil during freeze-thaw period. Soil totalcarbon, total nitrogen and ammonium nitrogen content, conductivity and moisture wereimportant environmental factors that significantly promoted the process of ammoniaoxidation in desert biocrust soil.The second period of freeze-thaw, ammonia-oxidizing archaea also mainlybelongs to Crenarchaeota in the desert soil. The community structure of AOA was notsignificantly affected by Biocrust and Biocrust-removal, the community diversity,richness and evenness of AOA in subsurface, under and deep soil were significantlyhigher than that in surface soil (P < 0.05). The dominant AOA community in the surfacesoil prefered the eutrophic environment with high water and nitrogen, while thedominant AOA community in the deep soil were the opposite, and the dominant AOAcommunity in the surface soil may be more conducive to the promotion of ammoniaoxidation.In summary, significant differences in environmental factors were caused byBiocrust and Biocrust-removal in the Gurbantunggut desert. The abundance of theammonia-oxidizing microorganism amoA gene was affected by various environmentalfactors, leading to spatiotemporal differentiation in AOA and AOB niche production indesert soil. Biocrust promoted AOA and AOB to be distributed according to temperatureand nitrogen substrate utilization efficiency difference by coupling environmentalfactors, and can promote the ammonia oxidation process of desert surface soil. Ourstudy provides knowledge for understanding of the nitrogen transformation intemperate desert. |
| Subject Area | 生物工程 |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | http://ir.xjlas.org/handle/365004/15437 |
| Collection | 中国科学院新疆生态与地理研究所 研究系统 |
| Affiliation | 中国科学院新疆生态与地理研究所 |
| First Author Affilication | 中国科学院新疆生态与地理研究所 |
| Recommended Citation GB/T 7714 | 刘鑫. 古尔班通古特沙漠生物结皮对氨氧化菌群差异分布的影响[D]. 北京. 中国科学院大学,2020. |
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