不同填闲模式对黄瓜根际土壤酶活性及细菌群落的影响

以温室连作3年黄瓜土壤为研究对象,以黄瓜为主栽作物,以青葱、小麦、油菜为不同季节填闲作物设置盆栽试验,采用常规化学方法、PCR-DGGE及qPCR技术,研究不同填闲模式对黄瓜土壤酶活性及细菌群落的影响.结果表明: 随着种植茬次的增加,填闲小麦处理的土壤脲酶、中性磷酸酶及转化酶活性均显著高于填闲青葱和油菜处理,同时油菜处理显著高于青葱处理;不同填闲模式间黄瓜根际土壤细菌群落结构不同,冬季填闲青葱和夏季填闲小麦处理维持了相对较高的多样性指数.qPCR检测结果表明: 随着种植茬次的增加,小麦处理的土壤细菌数量显著高于青葱和油菜处理.综上,不同填闲模式对土壤酶活性和细菌群落均产生一定影响,改变了土壤环境,其中夏季填闲小麦能保持相对较高的土壤酶活性、土壤细菌群落结构多样性及细菌数量.
     

Altering the mineral composition of soil causes a shift in microbial community structure

This study tests the hypothesis that altering the mineral composition of soil influences microbial community structure in a nutrient-deficient soil. Microcosms were established by adding mica (M), basalt (B) and rock phosphate (P) to soil separately, and in combination (MBP), and by planting with Lolium rigidum, Trifolium subterraneum or by leaving unplanted. The effects of mineral and plant treatments on microbial community structure were assessed using automated ribosomal intergenic spacer analysis. Bacterial community structure was significantly affected by both mineral (global R=0.73 and P<0.001) and plant (global R=0.71 and P<0.001) treatments, as was the fungal community structure: mineral (global R=0.65 and P<0.001) and plant (global R=0.65 and P<0.001) treatments. All pairwise comparisons of bacterial and fungal communities between different mineral treatments and between different plant treatments were significantly different (P<0.05). This study has shown that mineral addition to soil microcosms resulted in substantial changes in both bacterial and fungal community structure, dependent on the type of mineral added and the plant species present. These results suggest that the mineral composition of soil may be an important factor influencing the microbial community structure in soil.     

Effects of Manure Compost Application on Soil Microbial Community Diversity and Soil Microenvironments in a Temperate Cropland in China

The long-term application of excessive chemical fertilizers has resulted in the degeneration of soil quality parameters such as soil microbial biomass, communities, and nutrient content, which in turn affects crop health, productivity, and soil sustainable productivity. The objective of this study was to develop a rapid and efficient solution for rehabilitating degraded cropland soils by precisely quantifying soil quality parameters through the application of manure compost and bacteria fertilizers or its combination during maize growth. We investigated dynamic impacts on soil microbial count, biomass, basal respiration, community structure diversity, and enzyme activity using six different treatments [no fertilizer (CK), N fertilizer (N), N fertilizer + bacterial fertilizer (NB), manure compost (M), manure compost + bacterial fertilizer (MB), and bacterial fertilizer (B)] in the plowed layer (0–20 cm) of potted soil during various maize growth stages in a temperate cropland of eastern China. Denaturing gradient electrophoresis (DGGE) fingerprinting analysis showed that the structure and composition of bacterial and fungi communities in the six fertilizer treatments varied at different levels. The Shannon index of bacterial and fungi communities displayed the highest value in the MB treatments and the lowest in the N treatment at the maize mature stage. Changes in soil microorganism community structure and diversity after different fertilizer treatments resulted in different microbial properties. Adding manure compost significantly increased the amount of cultivable microorganisms and microbial biomass, thus enhancing soil respiration and enzyme activities (p<0.01), whereas N treatment showed the opposite results (p<0.01). However, B and NB treatments minimally increased the amount of cultivable microorganisms and microbial biomass, with no obvious influence on community structure and soil enzymes. Our findings indicate that the application of manure compost plus bacterial fertilizers can immediately improve the microbial community structure and diversity of degraded cropland soils.     

Effects of fertilization on bacterial community structure and function in a black soil of Dehui region estimated by Biolog and PCR-DGGE methods

Soil microbial community structure and function are commonly used as indicators for soil quality and fertility. In this paper, the bacterial community structure and function in a black soil of Dehui region influenced by fertilization were investigated by Biolog and PCR-DGGE (polymerase chain reaction-denaturing gradient gel electrophoresis) methods. Biolog examination showed that substrate richness and catabolic diversities of bacterial communities were the highest in the treatment of farm yard manure, and the lowest in the chemical fertilizer treatment. DGGE fingerprint showed that the majority of bands were similar among all treatments, suggesting that microbial communities with those bands were stable, and not influenced by fertilization. In general, chemical fertilizer decreased the diversity of soil bacterial communities. The PCA (principal component analysis) plots of Biolog and DGGE revealed that the structure and function of bacterial communities were similar in the non-fertilized control and the treatment of farm yard manure alone, which inferred that the application of farm yard manure increased the quantity of soil microbes but had less effect on the changes of community structure. The catabolic function was similar, but the composition structure differed between the treatments of chemical fertilizer alone and combined application of farm yard manure with chemical fertilizer. These results suggest that the use of chemical fertilizer mainly decreased the catabolic activity of the fast growth bacteria or eutrophic bacteria.     

Responses of soil bacterial and fungal communities to reciprocal transfers of soil between adjacent coniferous forest and meadow vegetation in the Cascade Mountains of Oregon

Little information exists on the responses of soil fungal and bacterial communities in high elevation coniferous forest/open meadow ecosystems of the northwest United States of America to treatments that impact vegetation and soil conditions. An experiment was conducted in which soil cores were reciprocally transplanted between immediately adjacent forests and meadows at two high elevation (∼1,600 m) sites (Carpenter and Lookout) in the H.J. Andrews Experimental Forest located in the Cascade Mountains of Oregon. Half of the cores were placed in PVC pipe (closed) to prevent new root colonization, whereas the other cores were placed in mesh bags (open) to allow recolonization by fine roots. A duplicate set of open and closed soil cores was not transferred between sites and was incubated in place. After 2 year, soil cores were removed and changes in fungal and bacterial biomasses determined using light microscopy, and changes in microbial community composition determined by PLFA analysis, and by length heterogeneity PCR of the internal transcribed spacer region of fungal ribosomal DNA. At both sites soil microbial community structures had responded to treatments after 2 year of incubation. At Carpenter, both fungal and bacterial community structures of forest soil changed significantly in response to transfer from forest to meadow, with the shift in fungal community structure being accompanied by a significant decrease in the PLFA biomarker of fungal biomass,18:2ω6,9. At Lookout, both fungal and bacterial community structures of forest soil changed significantly in response to open versus closed core treatments, with the shift in the fungal community being accompanied by a significant decrease in the 18:2ω6,9 content of closed cores, and the shift in the bacterial community structure being accompanied by a significant increase in bacterial biomass of closed cores. At both sites, fungal community structures of meadow soils changed differently between open and closed cores in response to transfer to forest, and were accompanied by increases in the18:2ω6,9 content of open cores. Although there were no significant treatment effects on the bacterial community structure of meadow soil at either site, bacterial biomass was significantly higher in closed versus open cores regardless of transfer.     

生态有机肥对番茄青枯病及土壤微生物多样性的影响

采用田间小区试验和FAMEs分析研究了不同用量生态有机肥对番茄青枯病的抑制效果和土壤微生物的影响。结果表明,连作地番茄青枯病发生率为100％,施生态有机肥显著地降低了连作地番茄青枯病的发生。用量为1kg·m^-2和0.5kg·m^-2时,番茄青枯病发生率分别为39％和50％,两种施肥量间差异不显著。施生态有机肥后土壤微生物群落脂肪酸指纹发生明显改变,革兰氏阴性菌生物标记物cyc17：0的含量增加,真菌生物标记物c18:2w6的含量增加,作为AM菌根的生物标记物c16:111c呈上升趋势。聚类分析表明,对照和施生态有机肥处理土壤微生物脂肪酸指纹之间的最短距离是1.08,不同施用量处理之间的最短距离是0.70。施用生态有机肥能调控土壤微生物群落结构,促进有益微生物的生长,增强土壤生态系统的稳定性和抑病性,从而提高了土壤质量。     

High-Resolution Melt Analysis for Rapid Comparison of Bacterial Community Compositions

In the study of bacterial community composition, 16S rRNA gene amplicon sequencing is today among the preferred methods of analysis. The cost of nucleotide sequence analysis, including requisite computational and bioinformatic steps, however, takes up a large part of many research budgets. High-resolution melt (HRM) analysis is the study of the melt behavior of specific PCR products. Here we describe a novel high-throughput approach in which we used HRM analysis targeting the 16S rRNA gene to rapidly screen multiple complex samples for differences in bacterial community composition. We hypothesized that HRM analysis of amplified 16S rRNA genes from a soil ecosystem could be used as a screening tool to identify changes in bacterial community structure. This hypothesis was tested using a soil microcosm setup exposed to a total of six treatments representing different combinations of pesticide and fertilization treatments. The HRM analysis identified a shift in the bacterial community composition in two of the treatments, both including the soil fumigant Basamid GR. These results were confirmed with both denaturing gradient gel electrophoresis (DGGE) analysis and 454-based 16S rRNA gene amplicon sequencing. HRM analysis was shown to be a fast, high-throughput technique that can serve as an effective alternative to gel-based screening methods to monitor microbial community composition.     

不同大豆连作年限对黑土细菌群落结构的影响

大豆连作导致作物产量下降、病原微生物富集和土壤退化等问题日趋严重。然而,目前关于大豆连作对土壤细菌群落结构组成及多样性分布的影响及发生机制尚不清楚。采用高通量测序技术,对大豆连作(不同年限)和大豆-玉米轮作下的黑土细菌16S rRNA基因进行测序分析。结果表明:轮作5年(CR5)和13年长期连作(CC13)处理显著增加了土壤pH、全氮(TN)、全磷(TP)和速效养分(AN、AP和AK)含量。与短期连作相比,CR5和CC13处理均提高了细菌群落的OTUs数量、PD值、Chao1指数和Shannon指数。聚类分析图谱结果显示细菌群落结构组成受到轮作和连作年限的双重影响,而土壤pH、TN、TP、AN、AP和AK是细菌群落结构发生变化的主要驱动因子(P0.05)。此外,VPA分析发现上述土壤因子中,土壤pH对细菌群落结构变化的贡献度最大。本研究证明大豆长期连作提高了土壤养分含量和细菌群落的丰富度和多样性指数,从分子生物学的角度证实大豆长期连作在一定程度上改善了土壤环境,为大豆连作障碍的研究提供了理论依据。     

基于高通量测序技术的不同年代公园绿地土壤细菌多样性

【背景】细菌多样性对绿地土壤生态功能有重要作用,但不同年代公园绿地土壤的细菌多样性尚未见相关报道。【目的】研究北京市不同年代公园绿地土壤细菌多样性和群落结构特征。【方法】利用IlluminaMiSeq测序技术,分别对北京市代表性古典公园和现代公园绿地土壤细菌群落多样性进行分析。【结果】北京市公园绿地土壤细菌群落共划分为45个已知的菌门,其中变形菌门、酸杆菌门、绿弯菌门和放线菌门为优势细菌群。土壤细菌群落α多样性分析结果表明,古典公园和现代公园的土壤细菌多样性存在差异,表现为古典公园的丰富度和多样性都高于现代公园。此外,土壤细菌群落相似性分析和主坐标分析都表明古典公园和现代公园的土壤细菌群落结构存在显著差异。冗余分析表明,对土壤微生物群落结构产生显著影响的环境因子分别为土壤含水量、有机质和全氮,其它土壤环境因子无统计学意义。首次引入公园年代作为影响因子进行冗余分析的研究结果表明,公园年代为影响公园细菌群落多样性的重要因子。【结论】不同年代公园绿地土壤细菌群落结构和物种多样性具有显著差异,随着公园年代的增加,土壤肥力和微生物多样性增加,绿地生态系统更稳定,可通过制定不同的绿地管理措施改变公园绿地土壤环境,进而优化土壤细菌群落结构,促进土壤碳氮养分循环,提高土壤肥力。     

Assessing the effect of air-drying and storage on microbial biomass and community structure in paddy soils

To understand the effect of air-drying pre-treatment, refrigeration, and freezing storages on microbial biomass and community structure in paddy soils, we measured total phospholipid fatty acid (PLFA) and PLFA profile after five treatments, including flooded (F), flooded-freezing (FF), flooded-air-drying (FAD), flooded-air-drying-freezing (FADF), and flooded-air-drying-refrigeration (FADR). FF and FADF treatments were followed by freeze-drying before analyzing the total PLFA and PLFA profile. The results showed that FF and FADF treatments increased the content of polyunsaturated fatty acids, but decreased that of branched chain saturated fatty acids. FAD treatment increased the concentrations of bacterial, aerobic bacterial, stress, Type I methanotrophs, and Gram-negative bacterial biomarkers, while it decreased the concentration of hydroxy fatty acid group and the ratios of cyclopropyl saturated fatty acids to their monoenoic precursors. FADR significantly decreased the concentration of total PLFA and all PLFA groups except for the mono-unsaturated fatty acid group. Statistical analysis with correspondence analysis showed that air-drying and storage changed the microbial community structure, but the effect of air-drying on soil microbial community structure was more pronounced than that of freezing. These results indicated that deep freezing followed by freeze-drying may be the most recommendable procedure before soil biochemical analysis in flooded paddy soils.     

Minerals in soil select distinct bacterial communities in their microhabitats

We tested the hypothesis that different minerals in soil select distinct bacterial communities in their microhabitats. Mica (M), basalt (B) and rock phosphate (RP) were incubated separately in soil planted with Trifolium subterraneum, Lolium rigidum or left unplanted. After 70 days, the mineral and soil fractions were separated by sieving. Automated ribosomal intergenic spacer analysis was used to determine whether the bacterial community structure was affected by the mineral, fraction and plant treatments. Principal coordinate plots showed clustering of bacterial communities from different fraction and mineral treatments, but not from different plant treatments. Permutational multivariate anova ( permanova ) showed that the microhabitats of M, B and RP selected bacterial communities different from each other in unplanted and L. rigidum , and in T. subterraneum , bacterial communities from M and B differed ( P <0.046). permanova also showed that each mineral fraction selected bacterial communities different from the surrounding soil fraction ( P <0.05). This study shows that the structure of bacterial communities in soil is influenced by the mineral substrates in their microhabitat and that minerals in soil play a greater role in bacterial ecology than simply providing an inert matrix for bacterial growth. This study suggests that mineral heterogeneity in soil contributes to the spatial variation in bacterial communities.     

采煤塌陷地不同施肥处理对土壤微生物群落结构的影响

采用磷脂脂肪酸(PLFA)分析方法,对山西长治襄垣五阳煤矿采煤沉陷区复垦土壤的微生物群落结构进行了研究。结果表明:施肥处理能够不同程度的增加土壤微生物的PLFA总量、细菌PLFA量和真菌PLFA量,其中化肥+有机肥处理下的土壤微生物PLFA总量,细菌PLFA量和真菌PLFA量增加作用比较明显,差异显著于对照处理;对不同施肥处理的复垦土壤微生物群落PLFA进行主成分分析也可得出化肥+有机肥处理下的土壤微生物的群落结构变化比较大,从因子载荷图上进一步分析可知,化肥+有机肥处理下的土壤中代表真菌的不饱和脂肪酸C18∶2ω6t、C18∶3ω6、18∶1ω9t、18∶3ω3的含量较高,这些脂肪酸将化肥+有机肥处理与单施化肥和对照处理区分开来,产生了明显的优势种群。土壤PLFA总量与土壤有机质、碱解氮、速效磷和速效钾含量都有很好的相关性,相关系数分别为0.76,0.85,0.67和0.67。     

不同施肥制度土壤微生物量碳氮变化及细菌群落16S rDNA V3 片段PCR产物的DGGE分析

应用化学分析和变性梯度凝胶电泳（DGGE）技术分离PCR扩增的16S rDNA的方法,研究了不同施肥制度对土壤微生物量碳、氮变化及微生物多样性的影响。结果表明,连续15a长期试验下,土壤微生物量碳（SMB-C）和微生物量氮（SMB-N）的含量大小均为长期撂荒（CK0）土壤高于农田土壤,而在农田土壤中,长期施肥的处理（NPK、NPKM、NPKSt和NPKF）高于长期不施肥处理（CK）,不同的种植制度中,长期复种轮作（NPKF）高于长期复种连作（NPK）;各处理的SMB-C/SOC（土壤有机碳）和SMB-N/TN（全氮）的比值的变化趋势与SMB-C和SMB-N变化一致;从PCR-DGGE分析,长期氮磷钾化肥配施有机肥（NPKM）处理的微生物量碳、氮的含量最高,微生物丰度最高,细菌物种最多,其次为长期撂荒（CK0）,CK处理细菌物种最少。UPGMC聚类分析表明NPK和NPKF处理细菌的群落结构相似,CK和CK0处理细菌的群落结构相似,而NPKM和NPKSt处理细菌的群落结构相似。     

长期施肥对新疆灰漠土土壤微生物群落结构与功能多样性的影响

以20a新疆国家灰漠土土壤肥力与肥料效益长期定位试验为平台,采用常规培养法,结合Biolog技术对可培养微生物、生理菌群数量和碳源利用进行测定分析,研究撂荒(CK0)、耕作不施肥(CK)、不同化肥(N、NK、NP、PK、NPK)、化肥配施低量高量有机肥(NPKM1和NPKM2)和秸秆还田(NPKS)等10种处理土壤微生物特征,揭示长期施肥对土壤微生物群落结构与功能多样性的影响。结果表明:(1)可培养微生物:与CK处理相比,CK0处理显著提高了细菌、放线菌和真菌的数量(P0.05),NPKS处理微生物数量则显著降低(P0.05);不同化肥处理的细菌(除PK处理外)、放线菌(除PK和N处理外)数量也有所增加,增幅在8.14%—135.70%和15.30%—44.78%之间;真菌数量(除NK处理外)则有一定幅度的降低;NPKM1和NPKM2处理,微生物数量最高,细菌分别增加了162.20%和173.75%,放线菌增加了34.39%和39.37%,真菌增加了63.33%和488.33%;(2)生理菌群:与CK0相比,CK处理显著提高了自生固氮菌和亚硝化细菌数量(P0.05),显著降低了氨化细菌和纤维素分解菌数量(P0.05);与CK相比,NPKM1和NPKM2处理显著提高土壤中与氮素转化有关的生理菌群数量(P0.05),不同化肥处理和NPKS处理的影响不相同,NPK处理显著高于其余处理(P0.05);(3)微生物碳源利用:微生物活性表现为NK、NPKM1、NPKM2N、NPK、CKPK、NPKSCK0、NP;CK0处理3个多样性指数以及NPKM1、NPKM2和NK处理Shannon(H)指数最高,其余施肥处理差异不显著;糖类、氨基酸类、羧酸类和胺类是微生物利用的主要碳源。(4)聚类分析表明,除NP处理外,施氮处理土壤有较为相似的碳源利用,细菌和真菌与养分之间有较好的相关性,可培养微生物和生理菌群与微生物碳源利用的相关性较差。因此,长期不同施肥对新疆灰漠土土壤微生物群落结构和功能多样性产生了显著的影响,长期耕作不施肥降低了土壤微生物群落结构和功能多样性,不同化肥配合施用对微生物群落的影响不同,NPK及NPK配施有机肥可提高土壤微生物多样性。     

石灰碳铵熏蒸联合生物有机肥对香蕉枯萎病和细菌群落的影响

以连续种植的香蕉枯萎病高发病蕉园为试验点,通过实时定量PCR和高通量测序等方法,研究了田间条件下石灰碳铵熏蒸联合生物有机肥施用对香蕉枯萎病的防治效果,以及对土壤细菌群落结构和组成的影响。结果表明: 与不熏蒸施用有机肥(OF)相比,香蕉枯萎病发病率在施用有机肥前使用石灰碳铵进行熏蒸处理(LAOF)和施用生物有机肥前使用石灰碳铵进行熏蒸处理(LABF)中分别降低了13.3%和21.7%,病原菌的拷贝数分别降低了22.4%和33.0%。与OF处理相比,石灰碳铵熏蒸联合不同肥料施用均显著降低了细菌的丰富度和多样性,形成了明显不同的群落结构,且熏蒸对群落组成的差异产生了决定性的影响。LABF的细菌丰富度和多样性均低于其他处理,群落组成也与其他处理存在明显差异。与OF处理相比,熏蒸处理(LAOF和LABF)显著增加了土壤中水恒杆菌、布鲁式菌和漯河杆菌属的相对丰度,且在LABF中的相对丰度均高于LAOF,水恒杆菌和布鲁式菌的相对丰度差异显著。在田间条件下,施用生物有机肥之前使用石灰碳铵进行熏蒸处理能够显著降低病原菌数量,改变土壤细菌群落结构,激发土壤有益微生物,从而减少香蕉枯萎病的发生。     

Bacterial community structure and diversity in a century-old manure-treated agroecosystem

Changes in soil microbial community structure and diversity may reflect environmental impact. We examined 16S rRNA gene fingerprints of bacterial communities in six agroecosystems by PCR amplification and denaturing gradient gel electrophoresis (PCR-DGGE) separation. These soils were treated with manure for over a century or different fertilizers for over 70 years. Bacterial community structure and diversity were affected by soil management practices, as evidenced by changes in the PCR-DGGE banding patterns. Bacterial community structure in the manure-treated soil was more closely related to the structure in the untreated soil than that in soils treated with inorganic fertilizers. Lime treatment had little effect on bacterial community structure. Soils treated with P and N-P had bacterial community structures more closely related to each other than to those of soils given other treatments. Among the soils tested, a significantly higher number of bacterial ribotypes and a more even distribution of the bacterial community existed in the manure-treated soil. Of the 99 clones obtained from the soil treated with manure for over a century, two (both Pseudomonas spp.) exhibited 100% similarity to sequences in the GenBank database. Two of the clones were possible chimeras. Based on similarity matching, the remaining 97 clones formed six major clusters. Fifty-six out of 97 were assigned taxonomic units which grouped into five major taxa: alpha-, beta-, and gamma-Proteobacteria (36 clones), Acidobacteria (16 clones), Bacteroidetes (2 clones), Nitrospirae (1 clone), and Firmicutes (1 clone). Forty-one clones remained unclassified. Results from this study suggested that bacterial community structure was closely related to agroecosystem management practices conducted for over 70 years.     

氮掺杂碳纳米颗粒对稻田根际土壤细菌群落的影响

氮掺杂碳纳米颗粒(N-CNPs)具有较高的农田氮肥增效潜力,但其对稻田根际土壤细菌群落结构和功能的影响尚不明确。本研究以连续3年施用低(1.2%,N-CNPs1)、中(6.7%,N-CNPs2)和高(9.3%,N-CNPs3)氮掺杂碳纳米颗粒的稻田根际土壤为研究对象,采用高通量测序技术和PICRUSt 功能预测方法研究其细菌群落组成和代谢功能变化。结果表明: 连续3年配施N-CNPs能提升稻田根际土壤细菌群落多样性,改变细菌群落功能;不同氮掺杂量水平间存在差异,其中以中氮掺杂量(N-CNPs2)碳纳米颗粒处理变化幅度最大。细菌群落分析结果指出,配施N-CNPs提升了根际土壤中变形菌门、酸杆菌门和疣微菌门的相对丰度,降低了浮霉菌门、绿弯菌门、硝化螺旋菌门和芽单胞菌门的相对丰度。PICRUSt 功能预测结果表明,在二级预测功能分类中,配施N-CNPs处理的氨基酸代谢、碳水化合物代谢和脂类代谢功能得到增强,而其他代谢功能则受到减弱。KEGG 直系同源基因簇丰度热图结果显示,N-CNPs2处理能提升根际土壤碳、氮代谢相关的细菌群落的相对丰度。     

施肥和土壤管理对土壤微生物生物量碳、氮和群落结构的影响

以中国科学院沈阳生态试验站的长期定位试验为平台,研究了不同施肥和土壤管理对潮棕壤微生物生物量碳、氮和群落结构的影响。结果表明,裸地和农田处理的微生物生物量碳、氮较低,但是农田处理下施肥增加了微生物生物量,其中NPK+M效果最明显。DGGE图谱显示,处理间细菌条带分布较相似,其中裸地的细菌多样性最高;长期施肥和土壤管理改变了土壤真菌群落结构,施肥增加了真菌多样性,且有机肥的影响大于化肥;不同处理间氨氧化细菌群落结构差异显著,NPK+M显著增加了氨氧化细菌多样性,且无机肥和有机肥对氨氧化细菌群落影响不同。施肥和土壤管理对细菌影响较小,但显著改变了真菌和氨氧化细菌的群落结构。聚类分析结果显示,土壤管理措施较施肥对细菌、真菌和氨氧化细菌群落的影响更为显著。     

Biolog和PCR-DGGE技术解析施肥对德惠黑土细菌群落结构和功能的影响

试验采用Biolog和PCR-DGGE技术研究了不同施肥处理对吉林省德惠市黑土细菌群落结构和功能的影响.Biolog试验结果表明,单施有机肥处理的土壤细菌群落对底物碳源利用种类最多,代谢功能多样性最高;而施用化肥处理降低了土壤细菌群落代谢功能.DGGE图谱表明,不同施肥处理的土壤细菌16S rDNA多数条带分布相同,说明这些细菌类群在黑土中较稳定,在本试验中未受到施肥的影响,但也有一些特殊条带出现或缺失,施用化肥处理降低了土壤细菌群落结构组成多样性.对Biolog和DGGE试验结果的主成分分析显示,未施肥和单施有机肥处理的土壤细菌群落结构和功能相似,表明单施有机肥处理主要是增加了土壤微生物的总量,而对黑土细菌群落结构组成影响是次要的;单施化肥和半量有机肥 化肥处理的土壤细菌群落代谢功能多样性相似,但其结构组成产生了分离.研究表明化肥处理主要是影响到土壤中快速生长和富营养的细菌类群,施用化肥降低了这些细菌类群的代谢活性.     

Community Structure Analyses Are More Sensitive to Differences in Soil Bacterial Communities than Anonymous Diversity Indices

Changes in the diversity and structure of soil microbial communities may offer a key to understanding the impact of environmental factors on soil quality in agriculturally managed systems. Twenty-five years of biodynamic, bio-organic, or conventional management in the DOK long-term experiment in Switzerland significantly altered soil bacterial community structures, as assessed by terminal restriction fragment length polymorphism (T-RFLP) analysis. To evaluate these results, the relation between bacterial diversity and bacterial community structures and their discrimination potential were investigated by sequence and T-RFLP analyses of 1,904 bacterial 16S rRNA gene clones derived from the DOK soils. Standard anonymous diversity indices such as Shannon, Chao1, and ACE or rarefaction analysis did not allow detection of management-dependent influences on the soil bacterial community. Bacterial community structures determined by sequence and T-RFLP analyses of the three gene libraries substantiated changes previously observed by soil bacterial community level T-RFLP profiling. This supported the value of high-throughput monitoring tools such as T-RFLP analysis for assessment of differences in soil microbial communities. The gene library approach also allowed identification of potential management-specific indicator taxa, which were derived from nine different bacterial phyla. These results clearly demonstrate the advantages of community structure analyses over those based on anonymous diversity indices when analyzing complex soil microbial communities.