不同pH紫色土中硝化作用及硝化微生物宏基因组研究

发布时间：2018-01-06 15:06

  本文关键词：不同pH紫色土中硝化作用及硝化微生物宏基因组研究　出处：《西南大学》2017年硕士论文　论文类型：学位论文

  更多相关文章： pH 紫色土 宏基因组 硝化微生物 硝化作用

【摘要】：紫色土作为我国特有的土壤资源,广泛分布于以四川盆地,该区紫色土占全国紫色土总面积的90%以上,而且较为肥沃,矿质元素丰富,是当地重要的农业土壤资源。众所周知,土壤中发生的硝化作用与农业环境污染密切相关,且是对pH高度敏感的生物化学过程,pH被认为是影响硝化作用及硝化微生物的一个关键因素。由于pH对土壤中发生的各种物理、化学以及生物过程都有着广泛的影响,其对土壤硝化作用的效应是综合的,弄清土壤pH对硝化作用的影响机制对于提高氮肥利用率和降低环境污染具有重要意义。首先,本文以四川盆地三种不同pH的紫色土为研究对象(酸性紫色土pH5.7;中性紫色土pH 7.3;石灰性紫色土pH 8.0),通过人为加酸或碱将三种不同初始pH的紫色土短期调节pH分别获得3个pH梯度的土壤子样品,添加8 mmol N kg-1硫酸铵保持田间持水量的60%置于28℃恒温培养箱黑暗培养,定期采样测定土壤硝态氮、铵态氮、pH值、氨氧化微生物丰度,研究pH的长期和短期改变对土壤硝化作用及氨氧化微生物的影响。结果如下:(1)三种不同pH紫色土原样在9天的培养过程中平均净硝化率为石灰性紫色土(7.02 mg kg-1d-1)中性紫色土(2.42 mg kg-1d-1)酸性紫色土(-0.23 mg kg-1d-1),土壤硝化作用的强度与pH呈显著正相关。三种不同pH紫色土原样中AOA/AOB比值为:酸性紫色土(126)中性紫色土(1.55)石灰性紫色土(0.6),说明酸性紫色土中AOA在数量上占主导地位,石灰性紫色土中AOB在数量上占主导地位,而在中性紫色土中AOA与AOB在数量上相当,可能都在硝化作用过程中起一定作用。(2)酸性紫色土三个子样品平均净硝化率为:-0.23、-0.22、-0.23 mg kg-1d-1;中性紫色土三个子样品pH 6.5-H2SO4,pH 7.3,pH 8.1-NaOH的平均净硝化率分别为:1.23、2.42、3.27 mg kg-1d-1;石灰性紫色土三个子样品平均净硝化率为:7.05、7.04、7.02 mg kg-1d-1。说明酸性及石灰性紫色土中,短期改变土壤pH并不能显著影响其硝化作用,而在中性紫色土中,短期提高或降低土壤pH会相应地增强或减弱其硝化作用强度。三种不同pH的紫色土子样品间AOA与AOB丰度无显著差异,且培养期间的变化趋势相同,表明短期改变pH不会显著影响土壤AOA和AOB的数量。(3)双因素方差分析发现长期pH改变对硝化作用影响极显著(F=569.547,P0.001),短期pH改变对硝化作用影响显著(F=4.723,P=0.02),长期pH改变对硝化作用的影响大于短期pH改变对硝化作用的影响。根据培养实验的结果,推测pH长期短期改变对硝化作用的影响机制不同,pH的长期改变是通过影响硝化微生物来影响硝化作用,为证明这一推测,对三种不同pH土壤原样提取总微生物DNA,运用Hiseq高通量测序技术对土壤中所有微生物进行测序分析,揭示长期pH改变对土壤微生物群落结构及功能基因的影响,结果如下:(1)Hiseq高通量测序总共发现89门,222纲,527目,1009科,2769属,14354种。所有土样中检测到10种相同的优势菌群,中性紫色土检测到一个独有的优势菌群Nitrospirae(硝化螺菌门),石灰性紫色土缺少优势菌群Thaumarchaeota(奇古菌门),Proteobacteria(变形菌门)在三种紫色土中均占比最多。(2)在所有序列中挑选功能基因发现,nxrA在所有土壤中占比最大,其次为nxrB,与AMO相关的功能基因在中性土占比最大,其次为石灰性土,酸性土最小,而且酸性土中没有检测到hao基因,石灰性土中的hao基因占比最大。(3)对微生物群落和土壤性质的相关性分析发现土壤的pH值、有机质、总氮、铵氮、硝氮和田间持水量对土壤微生物的群落结构都具有显著的相关性,且土壤pH对微生物群落的影响最大(r2=0.9985,P=0.001);通过冗余分析发现,三种不同pH紫色土的微生物群落结构差异很大。总氮,田间持水量,有机质和铵氮是影响酸性紫色土微生物群落的主要因素,而pH和硝氮则分别对中性及石灰性紫色土群落结构的影响明显。综合全文分析发现,三种不同pH紫色土中微生物群落结构差异极大,土壤pH与硝化作用呈显著正相关,pH长期改变是通过改变土壤硝化微生物群落结构和功能来影响硝化作用,而pH的短期改变是通过改变底物有效性来影响土壤硝化作用。
[Abstract]:Purple soil as a soil resource of China, is widely distributed in the Sichuan basin, the purple soil in this area accounted for more than 90% of the total area of purple soil, and more fertile, rich mineral elements, is important to the local agricultural soil resources. As everyone knows, soil nitrification occurred closely related to agricultural environmental pollution, and the biochemistry process is highly sensitive to pH, pH is considered to be a key factor affecting nitrification and nitrifying microorganisms. Because of various physical pH occurring in soil, chemical and biological processes have a broad impact, its effect on soil nitrification is the comprehensive effect, clarify the mechanism of pH on soil nitrification the role for improving the utilization rate of nitrogen fertilizer and reduce the pollution of the environment is of great significance. Firstly, this paper takes the Sichuan basin with three different pH in purple soil as the research object (purple acidic soil, neutral purple pH5.7; Soil pH 7.3; calcareous purple soil pH 8), by adding acid or alkali short of purple soil in three different initial pH regulation of pH obtained 3 pH soil samples were graded, 60% placed in a constant temperature of 28 DEG C to add 8 mmol N kg-1 ammonium sulfate to keep the field capacity incubator dark culture, regularly sampling and determination of soil nitrate nitrogen, ammonium nitrogen, pH value, microbial abundance of ammonia oxidation, pH long and short term effect on soil nitrification and ammonia oxidizing microorganisms. The results are as follows: (1) it is three kinds of different pH in purple soil during the 9 day culture average net nitrification rate for Calcareous purple soil (7.02 mg kg-1d-1) neutral purple soil (2.42 mg kg-1d-1) in acid purple soil (-0.23 mg kg-1d-1), soil nitrification intensity was positively correlated with pH. AOA/AOB three different pH ratio: purple soil is acidic purple soil (126) neutral (1.55) calcareous purple soil Purple soil (0.6), shows that Acidic Purple Soil AOA is dominant in quantity, in calcareous purple soils AOB dominated in number, while in neutral purple soil AOA and AOB in number, may play a role in the process of nitrification in acid purple soil. (2) three sub sample average net nitrification rate is: -0.23, -0.22, -0.23 mg kg-1d-1; neutral purple soil samples of pH 6.5-H2SO4 three, pH 7.3, the average net nitrification rate were: pH 8.1-NaOH 1.23,2.42,3.27 mg kg-1d-1; calcareous purple soil of three sub samples of the average net nitrification rate is: 7.05,7.04,7.02 mg kg-1d-1. acid and calcareous purple in the soil, short-term changes in soil pH did not significantly affect the nitrification, while in neutral purple soil, short-term increase or decrease the soil pH will correspondingly increase or decrease the nitrification intensity. Three kinds of purple soil with different pH samples between AOA and AO No significant differences in B abundance, and culture during the same trend, indicating that short-term changes of pH did not significantly influence the amount of soil AOA and AOB. (3) two factor variance analysis showed that the long-term pH changes had significant effect on nitrification (F=569.547, P0.001), short-term pH change significant effect on nitrification (F=4.723, P=0.02) pH, long-term effect on nitrification is greater than the short-term impact of pH changes on nitrification. According to the experimental results that pH training, short-term and long-term effect mechanism on nitrification, long-term changes in pH is to influence nitrification by affecting microbial nitrification, to confirm this hypothesis, three different kinds of soil pH it is the extraction of total microbial DNA, using high-throughput Hiseq sequencing technology to sequence analysis of all microorganisms in the soil, revealing the long-term impact of pH changes on soil microbial community structure and function of genes, results Are as follows: (1) Hiseq high-throughput sequencing found a total of 89 phyla, 222 classes, 527 orders, 1009 families, 2769 genera, 14354 species. All soil samples were detected in the same 10 dominant bacteria, neutral purple soil detected a unique advantage of flora Nitrospirae (nitrification Spirillum door), lime the lack of purple soil bacteria (Thaumarchaeota bacteria, Proteobacteria odd gate) (Proteobacteria) in three kinds of purple soil are accounted for most. (2) selection of functional genes found in all sequences, nxrA in all the soil in the largest proportion, followed by nxrB, the function of genes associated with AMO in neutral soil accounted for the largest, followed by calcareous soil, acidic soil is minimum, and no acid soil were detected in the Hao gene, Hao gene in calcareous soil. The largest proportion (3) of correlation between microbial communities and soil properties analysis showed that soil pH value, organic matter, total nitrogen, ammonium nitrogen. The nitrate nitrogen and the field capacity of soil The microbial community structure were significant, and the effect of pH on soil microbial communities (r2=0.9985, P=0.001); the maximum by redundancy analysis showed that microbial community structure between three different pH of purple soil. The total nitrogen, soil water, organic matter and ammonia nitrogen are the main factors affecting the acid purple soil microbial community the pH and nitrate respectively influence on neutral and calcareous purple soil microbial community structure significantly. The analysis found that three kinds of microbial community structure in different pH in purple soil, soil pH was positively correlated with nitrification, pH long-term change is to influence nitrification denitrification by changing the soil microbial community the structure and function of pH, and the short-term change is to influence soil nitrification by changing substrate availability.

【学位授予单位】：西南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S155.25

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