土壤与基质栽培系统对生菜(Lactuca sativa)根际细菌群落的影响

以生菜(Lactuca sativa)"申选5号"与"罗莎红"为材料,采用PCR-DGGE和Real-Time PCR技术,分析了土壤栽培系统和基质栽培系统根际细菌群落的差异。Real-Time PCR检测结果表明,基质栽培的两个生菜品种根际细菌数量均显著高于土壤(P0.05);PCR-DGGE图谱条带结果表明,根际细菌群落多样性基质高于土壤。栽培系统是造成多样性差异的主要原因,但也与品种有关:"申选5号"基质的Shannon-Wiener指数(H),Simpson指数(D)和均匀度(E)均显著高于土壤(P0.05);"罗莎红"基质的H显著高于土壤,而D和E无显著差异。结合土壤和基质理化性质的RDA分析结果,土壤和基质具有不同的细菌群落,p H值与硝态氮是塑造根际细菌群落的主要因子,含水量、碳氮比和有效磷与细菌群落的形成呈正相关。     

镉污染对烤烟根际土壤细菌和真菌群落结构的影响

根际土壤微生物是根际土壤生态系统的重要组成部分,为了明确镉污染条件下烤烟根际土壤微生物群落结构变化,采用全生育期盆栽方法,利用分子生物学PCR-DGGE技术,对不同浓度镉污染下烤烟根际细菌和真菌的群落结构进行了分析,结果表明:(1)镉污染浓度为4 mg kg-1处理的根际土壤细菌群落条带数,明显少于其他处理;随镉污染浓度的增加,一些土壤细菌类群逐渐消失,但特定细菌对高浓度镉污染具有较强的耐受能力;根际细菌可归入8个类群,Bacterium ellin、Acidobacteria酸杆菌和Mycobacterium分枝杆菌属对不同浓度镉污染具有较强的适应能力,其中leptolyngbya瘦鞘丝藻属能适应中等浓度的镉污染,在该浓度下,该微生物可大量繁殖为优势种群。(2)随着镉污染浓度增加,部分特有真菌类群出现,但是在中等镉浓度(4 mg kg-1)处理下,部分真菌类群消失;真菌群落结构可归入4个类群,其中优势和共有类群为Fusarium镰刀菌属和未知菌属,对不同浓度镉污染耐受性较强;Acremonium sclerotigenum硬化支顶孢霉对镉污染反应敏感,Rhizopus根霉菌属嗜好高浓度镉的真菌。     

连作对再植枸杞根际细菌群落多样性和群落结构的影响研究

受枸杞道地产区土地资源等因素限制,连作障碍已成为影响枸杞产业发展的重要原因之一,导致严重的经济损失.研究连作条件下枸杞农田土壤生态系统微生物群落的演替规律对枸杞产业的可持续发展具有重要的理论意义.以宁夏银川市南梁农场连作多年的枸杞地为研究对象,利用Illumina MiSeq测序技术分析了连作对再植枸杞根际/非根际细菌群落的影响.结果表明,连作地显著抑制再植枸杞苗地径的增加,且其土壤pH较对照样地显著降低(p<0.05).测序结果证实,与对照样地相比,连作地再植枸杞根际土壤细菌物种数显著降低(p<0.05),细菌群落α多样性下降(p>0.05).主坐标分析表明,连作和对照样地间枸杞非根际细菌群落结构无明显差异,但连作显著改变再植枸杞根际细菌的群落结构.对细菌群落丰度的统计分析发现,连作地枸杞根际浮霉菌门、非根际假单胞菌门的相对丰度较对照样地显著降低(p<0.05).此外,冗余分析结果表明:枸杞园土壤pH和有效磷含量是影响枸杞非根际土壤细菌群落结构变化的主要因素,分别解释了41.8%和35.4%的群落结构变化(p<0.05),其他土壤因子无统计学意义,但土壤理化因子对再植枸杞根际细菌群落结构变化的影响均未达显著水平.这些结果证实连作能够显著抑制再植枸杞生长、影响再植枸杞根际细菌群落结构和多样性,干扰枸杞与土壤细菌群落间的互作关系.这些研究结果将为解析枸杞连作障碍机制提供理论基础.     

施氮和间作花生对木薯根际土壤细菌群落结构的影响

在等量施肥条件下,木薯间作一季花生,是否具有间作优势,间作模式中木薯根际土壤细菌群落结构如何变化,相关研究报道较少。以木薯品种"华南205"、花生品种"粤油200"为试验材料,设计施氮、不施氮2个处理和等量施肥条件下的3种种植模式(木薯单作、花生单作、木薯间作花生),采用高通量测序技术,研究施氮和间作花生对木薯根际土壤细菌群落结构的影响。结果表明,在等量施肥条件下,木薯-花生间作的土地当量比大于1,表现出间作优势。施氮和间作花生对木薯根际土壤细菌的多样性无显著影响。4个优势细菌门类依次为绿弯菌门、变形菌门、放线菌门和酸杆菌门。不同处理间的菌门Saccharibacteria的差异极显著,施氮显著降低了疣微菌门的相对丰度。木薯根际土壤细菌的属数量共464个。相对丰度排名前30的菌属中,不同处理间菌属Acidobacteriaceae__Subgroup_1_和Sphingomonas的差异达显著或极显著水平,施氮显著降低了菌属Subgroup_7的相对丰度,显著提高了菌属Acidothermus的相对丰度。主成分分析表明,施氮对细菌群落组成的影响大于种植模式;冗余分析得出,有机质、pH值显著影响细菌属水平群落组成。     

毒死蜱对棉花根际土细菌群落多样性和结构的影响

通过室内盆栽试验模拟自然环境条件,采用高效液相色谱(HPLC)和末端限制性片段长度多态性(T-RFLP)技术,研究了土壤使用推荐剂量(5 mg·kg~(-1))及推荐剂量的2倍、3倍和4倍(10 mg·kg~(-1)、15 mg·kg~(-1)、20 mg·kg~(-1))毒死蜱对棉花根际土壤细菌群落多样性和结构的影响,以不施用毒死蜱的土壤为对照。结果表明,5 mg·kg~(-1)、10 mg·kg~(-1)、15 mg·kg~(-1)和20 mg·kg~(-1)毒死蜱在土壤中的半衰期分别为10.04 d、11.36 d、11.55 d和12.16 d,60 d时基本完全降解。毒死蜱处理60 d后,棉花生物量显著降低;毒死蜱浓度越高,棉花生物量越低。无毒死蜱条件下不同取样时间根际细菌多样性无显著差异,毒死蜱处理组前30 d细菌多样性均显著降低,60 d时毒死蜱处理组细菌多样性恢复到正常水平。研究发现毒死蜱浓度越高对细菌多样性抑制作用越显著,恢复越缓慢。主成分分析结果发现,第10 d、30 d和60 d毒死蜱处理组与对照组细菌群落结构差异显著,其中60 d时20 mg·kg~(-1)毒死蜱处理组差异最显著,即使土壤中毒死蜱完全降解,根际细菌群落结构仍不会恢复到正常水平。60 d时,被毒死蜱抑制的细菌有硝化刺菌属(Nitrospina sp.)和Cellulophaga sp.等,被激活的有芽孢杆菌属(Bacillus sp.)和链霉菌属(Streptomyces sp.)等。可见,毒死蜱的引入,重新构建了土壤细菌群落结构,显著影响棉花生长,对棉花根际土壤微生态环境冲击较大,应对其生态安全性予以重视。     

亚热带四种主要植被类型土壤细菌群落结构分析

应用PCR-DGGE方法分别对天目山和玲珑山的四种典型森林土壤细菌群落结构进行了研究分析。结果表明,阔叶林、杉木林、马尾松林和毛竹林在天目山土壤中的DGGE条带数分别为49、45、51和51条,在玲珑山土壤中的DGGE条带数分别为42、4i多是奥前啊2、44和48条。不同森林植被土壤DGGE带谱差异不明显,天目山和玲珑山4种森林土壤分别有31条和23条共性条带,分别占总数的61%和48%以上,然而每种林分也有各自的特征条带。相对而言,两个样地杉木林与其他三种林分的土壤细菌群落结构相似度较低,相似值分别为0.72和0.68,其土壤细菌多样性指数也明显低于其他3种林分,而毛竹林和马尾松林多样性指数则没有显著差异。同时分析两个采样区的土壤细菌DGGE发现,土壤性质对细菌群落结构的影响大于植被。     

炭疽病发病草莓与健康草莓根际细菌群落结构及功能差异

  目的   比较研究炭疽病不同发病程度草莓根际微生物群落结构并开展基因功能预测分析,为指导农田管理及筛选草莓炭疽病拮抗菌提供理论依据和参考。  方法  采集设施栽培大棚中健康和不同发病程度的草莓植株根际土壤,利用Illumina Miseq测序比较分析不同发病程度对草莓根际细菌多样性,根际细菌门、属水平群落组成特征的影响。  结果  发病植株根际细菌多样性显著低于健康植株,其中轻度发病草莓根际细菌丰富度ACE降低了7.2%,而中度发病草莓根际细菌丰富度降低了11%。草莓根际土壤的优势菌群为变形菌门、放线菌门和拟杆菌门,不同发病程度的草莓根际土壤的细菌群落结构发生了显著改变,其中发病草莓显著提高了根际土壤中芽孢菌属和亚栖热菌属的相对丰度,而降低了与促生功能相关的黄杆菌属和伯克氏菌属的相对丰度。PICRUSt2分析表明,炭疽病显著提高草莓根际细菌的细胞交流、细胞传递和分解,转录以及循环等功能,而降低了脂质代谢和消化功能。  结论  本研究表明炭疽病显著降低草莓根际细菌多样性,并改变细菌群落结构,降低了促进草莓营养吸收细菌种类的相对丰度,改变了根际细菌功能特征,研究结果为指导草莓生产管理和筛选抗病微生物提供参考。     

根表功能细菌生物膜及其在土壤有机污染控制与修复中的潜在应用价值

土壤中的有机污染物可从根系进入植物体内,并可进一步通过食物链富集,从而威胁人群健康。植物根际微生物种类繁多、数量巨大,其中很多根际细菌可通过成膜作用在植物根表形成细菌生物膜,协助植物抵抗外界的不良环境或促进植物生长。有机污染物在被植物根系吸收的过程中,多需经过根表细菌生物膜这一特殊界面。综述了根际细菌在植物根表的成膜作用,以及根表功能细菌生物膜对污染物根际环境过程的影响及作用机理,分析了利用根表功能细菌生物膜调控植物吸收有机污染物的可行性,试图为防治土壤有机污染、降低作物污染风险、保障农产品安全等提供理论依据。     

间作刺槐对魔芋根际细菌群落结构及软腐病发生的影响

为研究间作刺槐对魔芋根际细菌群落结构的影响及其与软腐病的关系,以深入理解特定作物间作模式下的根际微生态特征。本试验设置塑料膜全隔（单作）、尼龙网网隔（半间作）和无隔（间作）3种刺槐‖魔芋根系分隔处理,采用高通量测序和荧光实时定量PCR(qRT-PCR)技术分析不同处理魔芋根系和根际土壤细菌多样性、群落组成和土壤氮循环相关基因表达丰度。结果表明,魔芋根系和根际土壤细菌α多样性指数均随着根系互作加强而明显提高。无隔处理根际细菌群落β多样性与全隔处理有明显差异。戴沃斯菌属（Devosia）、极地所菌属（Pricia）、藤黄单胞菌属（Luteimonas）、链霉菌属（Streptomyces）及溶杆菌属（Lysobacter）相对丰度值在所有处理根系和土壤中均较大;原小单孢菌属（Promicromonospora）相对丰度在网隔处理土壤中最高;链霉菌属、根瘤菌属（Rhizobium）和溶杆菌属相对丰度在网隔和无隔魔芋根系和土壤中较大。与全隔相比,无隔处理显著提高了土壤氮循环相关固氮酶基因（nifH）、亚硝酸还原酶基因（nirS）、氧化亚氮还原酶基因（nosZ）和氨单加氧酶基因（AOA amoA...     

不同栽培模式对黄瓜根际土壤酶活性及细菌群落结构的影响

分别以小麦、燕麦、毛葱、芹菜、白菜与黄瓜伴生或套作,研究了不同栽培模式对黄瓜根际土壤酶活性及细菌群落结构的影响,为连作土壤环境修复提供理论依据。结果表明:小麦/黄瓜、燕麦/黄瓜伴生,毛葱/黄瓜套作显著提高了根际土壤过氧化氢酶活性（P0.05）;芹菜/黄瓜套作和小麦/黄瓜伴生显著提高了根际土壤过氧化物酶活性（P0.05）;芹菜/黄瓜套作显著提高了根际土壤脲酶活性（P0.05）;不同栽培模式均显著提高了各时期根际土壤转化酶活性（P0.05）。PCR-DGGE分析结果显示,不同栽培模式在一定程度上提高了黄瓜根际土壤细菌群落结构多样性。DGGE条带测序显示,黄瓜根际土壤细菌大多与不可培养的细菌种属具有较高的同源性,测序比对推测,主要分属于-变形菌纲（Alphaproteobacteria）、-变形菌纲（Betaproteobacteria）、鞘脂杆菌纲（Sphingobacteria）和芽单胞菌纲（Gemmatimonadetes）四个纲。本研究说明不同栽培模式对土壤酶活性和土壤细菌群落结构均产生一定影响,改变了土壤环境,其中小麦与黄瓜伴生栽培模式效果较好。     

土壤中多环芳烃的分布特征及其来源分析

利用气相色谱法分析了南充市10个不同功能区表层土壤中美国环保署规定的16种优控多环芳烃（PAHs）的含量和组分特征,运用同分异构体比率揭示了其污染来源。研究表明,该区土壤中PAHs的含量在9.1～2269.1μg·kg-1之间,而且工业区的残留量大于农业区和居民区的残留量。按PAHs的环数来分,在工业污染区PAHs的含量总的趋势是四环〉二环〉三环〉五环〉六环;农业和居民区二环〉三环〉五环〉四环〉六环。该污染状况与国内外相关研究比较,处于中等污染水平。煤、木材和化石的燃烧是该地区土壤中PAHs污染的主要来源,苯并（a）蒽和菲是主要的超标化合物。     

Isolation and Determination of Polycyclic Aromatic Hydrocarbons in Surface Runoff and Sediments

The distribution of Polycyclic Aromatic Hydrocarbons (PAHs) was investigated in surface runoff and sediments of Lagos, Osogbo and Ile-Ife Western areas of Nigeria. Method for the analysis of PAHs was based on Liquid-Liquid extraction of the runoff and a soxhlet extraction of the sediments followed by a clean up adsorption procedure. The PAHs were separated and quantified by Gas Chromatography-Mass spectrometry (GC-MS) technique. A blank experiment was done using triply distilled water and following the same procedure for the samples to establish blank levels. In both street runoff and sediments 13 PAHs were identified and quantified. At Osogbo and Ile-Ife areas, the mean levels of PAHs in surface runoff ranged between 0.10–15.81 mg L^-1 while in the Lagos area the levels were between 0.1–73.72 mg L^-1. Generally, the PAH levels in surface runoff of Lagos constitute 53.03 mg L^-1 average ∑ PAH detected in the study area compared to 31.96 mg L^-1 average ∑ PAH contribution made by samples from Osogbo and Ile-Ife. The levels of PAHs in sediments are relatively higher compared to those of the street runoff in the study area. PAHs in sediment of Lagos contribute an average of 228.57 mg kg^-1 ∑ PAH to the total sediment PAH burden compared to Osogbo and Ile-Ife areas that contribute only 91.13 mg kg^-1 average ∑ PAH to the total PAH burden of the study area. The relatively higher average ∑ PAHs reported for Lagos area compared with those of Osogbo and Ile-Ife, is consistent with higher industrial activities and traffic density of the former (1000–10000 vehicles/hr) than the later (450–1500 vehicles/hr).     

Particle-associated Polycyclic Aromatic Hydrocarbons in the Atmosphere of Hong Kong

Polycyclic aromatic hydrocarbons (PAHs) in total suspended particulates (TSP) collected at six rural and urban stations in Hong Kong from 1993–1995 using high volume air samplers were identified using GC-MS (gas chromatography-mass spectrometry). The results showed that the PAHs exhibited distinct spatial and seasonal variability. The total PAH content (ΣPAH) in the samples ranged from 0.41 to 48 ng m^-3. The unsubstituted analogs are the characteristic products of high temperature combustion processes. The highest average ΣPAH was measured at the street-level station in Mong Kok indicating that vehicles were high PAHs contributors. The rural station at Hok Tsui exhibited the lowest PAH level, however; influences of city plumes could be seen when northerly or northeasterly winds prevailed in the winter. All stations experienced the highest loading of PAHs in autumn and the lowest in summer; the former was 2.8 times greater than the latter. This seasonal variability is due to the Asian monsoon system, precipitation, micrometeorology, and the rate of photodegradation. In summer, Hong Kong experiences relatively clean oceanic air and high rates of precipitation and photodegradation, while upon the onset of the winter monsoon, local air mass is replaced by polluted air streams from the Asian continent. Benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(e)pyrene, indeno(1,2,3-cd)pyrene and benzo(ghi)perylene were the dominant species in the samples. The PAH distribution patterns at different stations were similar within each season. However, seasonal variations existed. For example, phenanthrene contributed up to 14% of the total PAH in summer, while the dominance of benzo(b)fluoranthene, benzo(k)fluoranthene was more significant in autumn and winter.     

Polycyclic Aromatic Hydrocarbons in Peat Mounds of the Permafrost Zone

Eurasian Soil Science - The accumulation of polycyclic aromatic hydrocarbons (PAHs) in the profiles of permafrost-affected peat mounds is related to certain groups of plant residues produced in the...     

Characterization of Polycyclic Aromatic Hydrocarbons Created in Lubricating Oils

Used lubricating oils are majorsources of polycyclic aromatic hydrocarbons (PAHs) inmarine environments. This study presents an improvedmethod for characterization PAHs in used lubricatingoils. Recoveries of sixteen certified PAHs spikedinto used lubricating oil indicated this method wasmore precise and efficient than those reportedpreviously. Aromatic and aliphatic compounds in usedlubricating oil were extracted by dimethylsulfoxide,then separated by a silica gel column using hexane anddichloromethane as solvents. Finally, gaschromatography-mass spectrometry was used inqualitative and quantitative analysis of various PAHsin oil samples. Sixteen certified PAHs andeighty-three other PAHs were identified and quantified usingPAH standards and previously reported retentionindices as references. The improved method was usedto determine PAH profiles in lubricating oil samplescollected from a gasoline-driven automobile aftervarious driving distances. One hundred and eightyaromatic compounds, including ninety-nine PAHs, wereidentified by the gas chromatographic method. Theseresults suggested that the new method was superior tomethods described in previous studies. Theconcentrations of PAHs, including the comparativelytoxic 5-ring PAHs, increased rapidly even after theautomobile had only been driven for a short distance. 2- and 3-ring PAHs, most of them are alkylated,dominated the PAH profiles of the collected oil samples.     

Effect of Composting on Polycyclic Aromatic Hydrocarbons Removal in Sewage Sludge

Changes in the concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) identified by the US Environmental Protection Agency as priority pollutants were investigated during the composting process of sewage sludge mixed with rapeseed marc (9:1, weight base). Results showed that total PAHs concentrations of the sludge sampled in different seasons had far exceeded the accepted Europe Union cut-off limits for land application. Phenanthrene, fluorene and dibenz(a, h) anthracene were dominant PAHs in the sludge, accounting for 62.8~69.6% of the total amount of the 16 PAHs. Composting appeared to be an effective method for the removal of PAHs in sewage sludge. After 50 days of composting, a significant reduction of concentration of the total PAHs was detected as compared with the initial concentration in composting material. The significant relationship between the biodegradation of organic matter and the losses of Σ16 PAHs during composting indicated that microbial degradation was the key process responsible for the efficient removal of PAHs from the sludge. Among all tested PAHs, fluorene was the most recalcitrant and became the primary residual PAH in the composted material. The lower removal rate of fluorene during composting was a limiting factor for the potential land application of the sludge. Further studies are needed to enhance the removal of fluorene in order to achieve a safe utilization of this sludge.     

微山湖表层沉积物中多环芳烃的分布及风险评价

采用现场采样及室内高效液相色谱分析测试的方法,探讨了微山湖表层沉积物中多环芳烃（PAHs）的分布,并进行了风险评价。结果表明,微山湖表层沉积物中16种优控PAHs的总量范围在324.93～1576.65ng.g-（1干重）之间,平均值为699.01ng.g-1,属中等污染水平,沉积物中的多环芳烃主要来源于煤炭、木材及石油的不完全燃烧。利用沉积物质量基准法（SQGs）、沉积物质量标准法分别对微山湖沉积物中多环芳烃的风险评价表明,严重的多环芳烃生态风险在微山湖沉积物中不存在,负面生物毒性效应则会偶尔发生,风险主要来源于低环的多环芳烃,以芴（Flu）和苊（Ace）为主。     

Composting of Wood Containing Polycyclic Aromatic Hydrocarbons (PAHs)

The addition of various nitrogen sources, such as liquid hog manure and mineral medium, to pine wood accelerated the composting process in Dewar vessels, which was obvious from the increased decomposition temperature and the more intensive oxygen consumption and carbon dioxide production. During composting in Dewar vessels of artificially PAH-contaminated pine wood soaked with liquid manure, the PAH degradation was influenced by the inoculum used. The fastest PAH degradation was achieved by compost addition, but the most intensive carbon dioxide evolution was measured with hydrocarbon-polluted soil as an additive. After 61 days, the PAH content of the wood was reduced from each 1000 mg/kg to 26 mg/kg of phenanthrene and 83 mg/kg of pyrene. The relation between the microbial wood decay and PAH degradation shows that the detoxification at least of artificially PAH-polluted wood demands only a partial wood decay.

A pilot scale percolator was applied to composting of artificially contaminated pine wood and really polluted waste wood. After 27 days of remediation, the portion of residual PAHs was higher in the case of the really polluted material. The slower degradation in the real waste wood may be explained by the lower bioavailability of pollutants in comparison with the artificially contaminated wood. In really polluted wood, the degradation rate of PAHs depended on their degree of condensation (the higher the number of aromatic rings the smaller the degradation rate was).     

土壤中多环芳烃和氨基甲酸酯等农药分析

应用超高效液相色谱和质谱串联技术对吉林省中部地区土壤中多环芳烃及氨基甲酸酯农药类成分进行含量测定分析。以超声波提取作为提取方法,以在线固相萃取作为纯化方法,以超高效色谱-三重四级杆质谱作为分析方法,共分离检测出12个多环芳烃类化合物,分别为:萘、苊、苊烯、氟、菲、蒽、芘、苯并[a]蒽、屈、苯并[a]芘、二苯并[a,h]蒽和茚并[1,2,3-cd]芘。11个氨基甲酸酯及其它类农药,分别为:灭多威,多菌灵,甲萘威,克百威,啶虫脒,涕灭威亚砜,涕灭威砜,苯醚甲环唑,阿维菌素,灭幼脲和氟虫腈。利用超声波提取和在线固相萃取法可以有效地提取纯化土壤中多环芳烃和氨基甲酸酯类农药。超高效液相色谱和质谱联用技术可以有效地分析食品中多环芳烃和有机氯农药类成分。     

烟草根表可培养细菌群落组成及典型菌群的促生特性研究

植物微生物组是维护植物生长发育、提升抗逆防病的重要调控因素。为发挥植物微生物促进烟草生长、改善烟草根区微生态功能作用,本研究从烟草根表分离筛选可培养细菌组,并对不同菌株的促生能力进行测定。结果表明：(1)从烟草根表分离并鉴定出可培养菌株310株,隶属于31个属,其中主要为芽孢杆菌属(Bacillus)、假单胞菌属(Pseudomonas);(2)对比分析发现假单胞菌属、芽孢杆菌属、寡养单胞菌属(Stenotrophomonas)和成对杆菌属(Dyadobacter)为4种供试土壤烟草根表共有的细菌类群;(3)对进一步筛选得到的16株菌株进行促生能力的测定,发现6株菌具有固氮能力,5株菌产铁载体,4株菌可溶解无机磷,4株菌产IAA;(4)盆栽试验验证16株菌株的促生效果,其中37.5%的菌株对烟草生长具有显著促进作用,烟草株高、总鲜物质量和地下部干物质量分别比对照提高35.1%、27.9%和30.7%。总之,从烟草根表分离获得多种具有促生能力的菌株,为未来构建促进烟草健康生长的复合菌剂提供了理论基础。