本文關(guān)鍵詞：不同pH紫色土中硝化作用及硝化微生物宏基因組研究　出處：《西南大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： pH 紫色土 宏基因組 硝化微生物 硝化作用

【摘要】：紫色土作為我國(guó)特有的土壤資源,廣泛分布于以四川盆地,該區(qū)紫色土占全國(guó)紫色土總面積的90%以上,而且較為肥沃,礦質(zhì)元素豐富,是當(dāng)?shù)刂匾霓r(nóng)業(yè)土壤資源。眾所周知,土壤中發(fā)生的硝化作用與農(nóng)業(yè)環(huán)境污染密切相關(guān),且是對(duì)pH高度敏感的生物化學(xué)過(guò)程,pH被認(rèn)為是影響硝化作用及硝化微生物的一個(gè)關(guān)鍵因素。由于pH對(duì)土壤中發(fā)生的各種物理、化學(xué)以及生物過(guò)程都有著廣泛的影響,其對(duì)土壤硝化作用的效應(yīng)是綜合的,弄清土壤pH對(duì)硝化作用的影響機(jī)制對(duì)于提高氮肥利用率和降低環(huán)境污染具有重要意義。首先,本文以四川盆地三種不同pH的紫色土為研究對(duì)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),通過(guò)人為加酸或堿將三種不同初始pH的紫色土短期調(diào)節(jié)pH分別獲得3個(gè)pH梯度的土壤子樣品,添加8 mmol N kg-1硫酸銨保持田間持水量的60%置于28℃恒溫培養(yǎng)箱黑暗培養(yǎng),定期采樣測(cè)定土壤硝態(tài)氮、銨態(tài)氮、pH值、氨氧化微生物豐度,研究pH的長(zhǎng)期和短期改變對(duì)土壤硝化作用及氨氧化微生物的影響。結(jié)果如下:(1)三種不同pH紫色土原樣在9天的培養(yǎng)過(guò)程中平均凈硝化率為石灰性紫色土(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),土壤硝化作用的強(qiáng)度與pH呈顯著正相關(guān)。三種不同pH紫色土原樣中AOA/AOB比值為:酸性紫色土(126)中性紫色土(1.55)石灰性紫色土(0.6),說(shuō)明酸性紫色土中AOA在數(shù)量上占主導(dǎo)地位,石灰性紫色土中AOB在數(shù)量上占主導(dǎo)地位,而在中性紫色土中AOA與AOB在數(shù)量上相當(dāng),可能都在硝化作用過(guò)程中起一定作用。(2)酸性紫色土三個(gè)子樣品平均凈硝化率為:-0.23、-0.22、-0.23 mg kg-1d-1;中性紫色土三個(gè)子樣品pH 6.5-H2SO4,pH 7.3,pH 8.1-NaOH的平均凈硝化率分別為:1.23、2.42、3.27 mg kg-1d-1;石灰性紫色土三個(gè)子樣品平均凈硝化率為:7.05、7.04、7.02 mg kg-1d-1。說(shuō)明酸性及石灰性紫色土中,短期改變土壤pH并不能顯著影響其硝化作用,而在中性紫色土中,短期提高或降低土壤pH會(huì)相應(yīng)地增強(qiáng)或減弱其硝化作用強(qiáng)度。三種不同pH的紫色土子樣品間AOA與AOB豐度無(wú)顯著差異,且培養(yǎng)期間的變化趨勢(shì)相同,表明短期改變pH不會(huì)顯著影響土壤AOA和AOB的數(shù)量。(3)雙因素方差分析發(fā)現(xiàn)長(zhǎng)期pH改變對(duì)硝化作用影響極顯著(F=569.547,P0.001),短期pH改變對(duì)硝化作用影響顯著(F=4.723,P=0.02),長(zhǎng)期pH改變對(duì)硝化作用的影響大于短期pH改變對(duì)硝化作用的影響。根據(jù)培養(yǎng)實(shí)驗(yàn)的結(jié)果,推測(cè)pH長(zhǎng)期短期改變對(duì)硝化作用的影響機(jī)制不同,pH的長(zhǎng)期改變是通過(guò)影響硝化微生物來(lái)影響硝化作用,為證明這一推測(cè),對(duì)三種不同pH土壤原樣提取總微生物DNA,運(yùn)用Hiseq高通量測(cè)序技術(shù)對(duì)土壤中所有微生物進(jìn)行測(cè)序分析,揭示長(zhǎng)期pH改變對(duì)土壤微生物群落結(jié)構(gòu)及功能基因的影響,結(jié)果如下:(1)Hiseq高通量測(cè)序總共發(fā)現(xiàn)89門,222綱,527目,1009科,2769屬,14354種。所有土樣中檢測(cè)到10種相同的優(yōu)勢(shì)菌群,中性紫色土檢測(cè)到一個(gè)獨(dú)有的優(yōu)勢(shì)菌群Nitrospirae(硝化螺菌門),石灰性紫色土缺少優(yōu)勢(shì)菌群Thaumarchaeota(奇古菌門),Proteobacteria(變形菌門)在三種紫色土中均占比最多。(2)在所有序列中挑選功能基因發(fā)現(xiàn),nxrA在所有土壤中占比最大,其次為nxrB,與AMO相關(guān)的功能基因在中性土占比最大,其次為石灰性土,酸性土最小,而且酸性土中沒(méi)有檢測(cè)到hao基因,石灰性土中的hao基因占比最大。(3)對(duì)微生物群落和土壤性質(zhì)的相關(guān)性分析發(fā)現(xiàn)土壤的pH值、有機(jī)質(zhì)、總氮、銨氮、硝氮和田間持水量對(duì)土壤微生物的群落結(jié)構(gòu)都具有顯著的相關(guān)性,且土壤pH對(duì)微生物群落的影響最大(r2=0.9985,P=0.001);通過(guò)冗余分析發(fā)現(xiàn),三種不同pH紫色土的微生物群落結(jié)構(gòu)差異很大�？偟�,田間持水量,有機(jī)質(zhì)和銨氮是影響酸性紫色土微生物群落的主要因素,而pH和硝氮?jiǎng)t分別對(duì)中性及石灰性紫色土群落結(jié)構(gòu)的影響明顯。綜合全文分析發(fā)現(xiàn),三種不同pH紫色土中微生物群落結(jié)構(gòu)差異極大,土壤pH與硝化作用呈顯著正相關(guān),pH長(zhǎng)期改變是通過(guò)改變土壤硝化微生物群落結(jié)構(gòu)和功能來(lái)影響硝化作用,而pH的短期改變是通過(guò)改變底物有效性來(lái)影響土壤硝化作用。
[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.

【學(xué)位授予單位】：西南大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：S155.25

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