發(fā)布時間：2018-08-08 15:38

【摘要】：甲醇是甲烷氧化過程的中間產(chǎn)物,高濃度的甲醇可能會對甲烷單加氧酶產(chǎn)生反饋抑制,從而抑制甲烷的氧化�；趍xaF和xoxF蛋白質(zhì)序列的系統(tǒng)發(fā)育分析結(jié)果顯示,甲醇脫氫酶蛋白質(zhì)家族組成至少有六種不同的獨立分支(mxaF和xoxFl-5)。而xoxF基因是最近新發(fā)現(xiàn)的甲基營養(yǎng)菌的甲醇脫氫酶。雖然,在海洋環(huán)境中利用xoxF基因檢測到多種甲醇氧化菌,但在濕地沉積物和草原土壤中的多樣性及分布還尚無報道。為了解濕地沉積物及草原土壤中甲醇氧化菌的多樣性,本文以內(nèi)蒙古高原典型濕地和草原作為研究區(qū)域,選擇重度富營養(yǎng)化的烏梁素海濕地、半干旱區(qū)錫林河水庫、錫林河圍封濕地,以及典型草原毛登牧場,采集表層土壤或沉積物作為研究對象,提取樣品總DNA并構(gòu)建xoxF5基因克隆文庫,共測序221個克隆子序列(132個OTUs)并進行甲醇氧化菌群落結(jié)構(gòu)及多樣性分析。研究結(jié)果如下:(1)三個不同濕地沉積物中都檢測出α-變形菌門(豐度:12～48%,下同),β-變形菌門(7～47%),γ 變形菌門(37～54%)的甲醇氧化菌,生境不同而有所差異。在屬水平上,Type Ⅰ甲烷氧化菌(Cluster 6和Cluster 8)是同時作為烏梁素海(WWT),錫林河水庫(XRR),錫林河濕地(XWT)的主要菌群(豐度分別17%,38%及22%)。其次,Hyphomicrobium屬相關(guān)的Cluster 3B是烏梁素海(WWT)和錫林河水庫(XRR)中的豐度較高(分別22%和41%)。而Methylibium sp.Root1272親緣菌群(OTU005)是錫林河濕地(XWT)特異的優(yōu)勢菌(16%)。還有,Beggiatoa相關(guān)Cluster 4(17%)也是烏梁素海特異性主要菌群。這些結(jié)果顯示,甲烷氧化菌也是濕地主要甲醇氧化菌,可能為其他氮或硫循環(huán)功能的甲醇氧化菌提供碳素營養(yǎng)。(2)毛登牧場草原土壤的甲醇氧化菌中包含α-變形菌門(63%),β-變形菌門(13%),γ-變形菌門(5%),厚壁菌門(17%)及放線菌門(2%)。其中,α-變形菌門的Hyphomicrobiu 相關(guān) Cluster 3B(16%)和Bradyrhizobi m親緣 Cluster 3A(23%),以及未知的厚壁菌門的未知的Cluster 5(20%)是主要功能菌群,另外γ-變形菌門的Type Ⅰ甲烷氧化菌(4%)。而且與濕地相比,Bradyrhizobium與未知的Cluster 5是草原特異菌群,在草原土壤中甲醇氧化菌可能對草原土壤氮循環(huán)起重要作用。(3)甲醇氧化菌的多樣性分析結(jié)果是毛登草原的香農(nóng)指數(shù)最高(H'=3.62),依次是錫林河濕地(3.32),錫林河水庫(3.18),烏梁素海濕地(2.88)。RDA分析結(jié)果表明,總磷,銨態(tài)氮及pH可能對甲醇氧化菌群組分及多樣性有一定的影響。
[Abstract]:Methanol is the intermediate product of methane oxidation, and high concentration of methanol may inhibit the oxidation of methane by feedback inhibition of methane monooxygenase. Phylogenetic analysis based on mxaF and xoxF protein sequences showed that there were at least six distinct branches (mxaF and xoxFl-5) of methanol dehydrogenase protein family. The xoxF gene is a newly discovered methanol dehydrogenase of methyl nutrition bacteria. Although a variety of methanol-oxidizing bacteria were detected by xoxF gene in marine environment, the diversity and distribution of methanol-oxidizing bacteria in wetland sediments and steppe soils have not been reported. In order to understand the diversity of methanol-oxidizing bacteria in wetland sediment and steppe soil, the typical wetland and steppe in Inner Mongolia Plateau were selected as the study area, the Wuliangsuhai wetland with heavy eutrophication and the Xilin River reservoir in semi-arid area were selected. The Xilin River enclosed wetland and typical grassland Maoden pasture were collected from the surface soil or sediment as the research object, the total DNA of the sample was extracted and the xoxF5 gene clone library was constructed. 221 clone sequences (132 OTUs) were sequenced and the community structure and diversity of methanol-oxidizing bacteria were analyzed. The results are as follows: (1) the methanol-oxidizing bacteria of 偽 -Proteus (abundance 12: 48, the same below), 尾 -Proteus (747%) and 緯 -Proteus (3754%) were detected in three different wetland sediments, with different habitats. At the generic level, methane-oxidizing bacteria (Cluster _ 6 and Cluster _ 8) are the main flora (abundance 17 38% and 22%) of (XWT) in (XRR), Xilin River wetland of (WWT), Xilin River Reservoir in Wuliangsuhai. The relative Cluster 3B of Hyphomicrobium was higher in (WWT) and Xilin Reservoir (22% and 41%, respectively). Methylibium sp.Root1272 phylogeny (OTU005) was the dominant strain of (XWT) in Xilin River wetland (16%). Beggiatoa related Cluster 4 (17%) is also the main specific flora of Uliangsuhai. These results show that methanogens are also the main methanol-oxidizing bacteria in wetlands. It may provide carbon nutrition for other methanol-oxidizing bacteria with nitrogen or sulfur cycling function. (2) Methanol-oxidizing bacteria in Maoden pastureland soil include 偽 -Proteus (63%), 尾 -Proteus (13%), 緯 -Proteus (5%), P. thuringiensis (17%) and Actinomycetes (2%). Among them, Hyphomicrobiu associated Cluster 3B (16%) and Bradyrhizobi m related Cluster 3A (23%) and unknown Cluster 5 (20%) of 偽 -Proteus phylum were the main functional flora, and Type 鈪，

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