亚硝化/电化学生物反硝化全自养脱氮工艺细菌形态及多样性研究

采用电镜观察和分子生物学手段16S rDNA克隆文库方法对亚硝化/电化学生物反硝化全自养脱氮工艺中的细菌进行了形态和多样性研究,从16S rDNA克隆文库中随机挑选60(61)个克隆子进行序列测定(约500bp),对测序结果进行BLAST比对和系统发育分析.结果表明,亚硝化段内的细菌主要为球状和椭球状的氨氧化细菌,以亚硝酸氮作为进水基质时,电化学反硝化生物段内细菌主要为短杆状和椭球状的脱氮菌.亚硝化/电化学生物反硝化脱氮系统中蕴藏着特有的微生物新资源.亚硝化段细菌类群的优势顺序为β-Proteobacteria类群(60.00%)、Bacteroidetes类群(28.33%)和Chloroflexi类群(11.67%).当电化学生物反硝化段进水氮基质为亚硝氮(429～543mg.L-1)和氨氮(412～525mg.L-1)时,细菌优势类群顺序为β-Proteobacteria(78.33%)类群和ε-Proteobacteria类群(21.67%);当电化学生物反硝化段进水氮基质为亚硝氮(519～578mg.L-1)时,细菌优势类群顺序为β-Proteobacteria类群(81.97%)、ε-Proteobacteria(16.39%)类群和γ-Proteobacteria类群(1.64%);优势类群变化不大,但每种类群中细菌的种类和数量变化较大,这主要是由进水基质变化导致.     

Effect of lime application on microbial community in acidic tea orchard soils in comparison with those in wasteland and forest soils

Lime application is a conventional technology to control acidification in tea orchard soils. We investigated the e ect of lime application on soil microbial community diversity in the soils of three tea orchards, wasteland and forest. The BIOLOG data showed that both the average well color development of all carbon sources and the functional diversity index increased with the liming rate in the tea orchards and the forest, but decreased in the wasteland. The phospholipid fatty acid (PLFA) analysis showed that the structural diversity index of soil microbial community increased with the liming rate in all the tea orchards, the wasteland and the forest. Lime application also increased the soil-bacterial PLFA content in all the soils. Soil fungal and actinomycete PLFAs in the tea orchards showed an increasing trend from 0 to 3.2 g CaCO3/kg application and then a decreasing trend from 3.2 to 6.4 g CaCO3/kg application. The principal component analysis of BIOLOG and PLFA data suggested that lime application had a significant e ect on soil microbial community structure, and land use had a greater e ect on soil microbial community structure compared to lime application.     

餐厨垃圾乳酸发酵过程中的微生物多样性分析

采用PCR-DGGE等分析手段,研究了餐厨垃圾乳酸发酵过程中的微生物种群动态变化.结果表明,餐厨垃圾不灭菌而接种的开放式发酵体系中微生物的多样性高于灭菌后接种的非开放式发酵体系,而乳酸产量也是前者高于后者.说明发酵体系中的微生物多样性与乳酸产量有很大的相关性.通过对部分条带的测序可知,餐厨垃圾开放式发酵体系中除含有接种用的嗜淀粉乳杆菌外,还含有很多土著乳酸菌,如Lactobacillus sp.、Lactobacillus casei和Lactobacillus plantarum,以及土著水解菌,如假单胞菌属(Pseudomonas sp.)等,这些土著菌的存在是促进乳酸发酵的重要因素.PCR-DGGE结合技术对于成分复杂的餐厨垃圾中的细菌种群结构的动态变化分析是可行的.     

溪源宫水源保护区浮游植物群落结构分析研究

文章主要对2011年8月至12月溪源宫水源保护区浮游植物群落结构进行调查分析。溪源宫水体共鉴定出浮游植物6门51属137种,主要都是以绿藻门、硅藻门、蓝藻门为主。通过采用浮游植物生物量以及多样性指数对研究区域水体进行了评价,结果表明溪源宫水源保护区水质状况较好。同时还将溪源宫水源保护区、闽江、山仔水库等不同水源地的浮游植物群落结构进行对比分析,发现不同营养状态下,水体中浮游植物群落结构有显著的不同。     

溶解氧变化对底泥酶活性及微生物多样性的影响

采用室内静态实验考察了溶解氧变化对底泥酶活性影响,同时采用BIOLOG ECO微平板构造了不同溶解氧水平下底泥微生物多样性指数。结果表明:高溶解氧条件下,底泥多酚氧化酶及过氧化物酶活性显著高于缺氧条件及厌氧条件(P<0.01),脱氢酶活性高于背景值;厌氧条件下脱氢酶、脲酶及碱性磷酸酶活性显著高于高溶解氧组、缺氧组及背景值(P<0.05);缺氧条件下硝酸盐还原酶活性显著高于高溶解氧组及厌氧组(P<0.05);蛋白酶活性受溶解氧水平变化的影响较小。BIOLOG ECO微平板法分析表明,溶解氧变化对底泥微生物多样性有不同程度的负面影响,微生物多样性的降低程度从大到小依次为高溶解氧组>厌氧组>缺氧组。主成分分析结果表明:缺氧条件及厌氧条件下,底泥微生物对大分子有机物的利用出现不同程度的降低,相对地,高溶解氧条件下微生物对大分子有机物的利用程度呈现先下降后上升的趋势;高溶解氧组及缺氧组底泥微生物对碳水化合物利用程度升高,厌氧组对碳水化合物利用程度降低。总之,高溶解氧条件更有利于形成底泥有机物完整的代谢循环,提高大分子有机物的利用程度。     

梯度负荷下果蔬垃圾厌氧消化性能及微生物群落结构的研究

为优化果蔬垃圾厌氧消化工艺,提高厌氧消化性能,本文通过逐级提高CSTR反应器进料负荷,研究不同负荷下的厌氧消化性能及相应的微生物群落结构变化规律.结果表明,随着进料负荷的增高,容积产气率、甲烷产气量、氨氮、碱度、TCOD、SCOD均逐渐增高,在最高负荷(负荷以VS计)2.50g·L-·1d-1时分别达到最大值:1.22L·L-1d-1,5.10L·d-1,1563.86mg·L-1,7572.23mg·L-1,13283.26mg·L-1,2075.03mg·L-1,甲烷含量及VFA分别稳定在52.46%～54.59%和(879.30±18.69)mg·L-1;同时利用PCR-DGGE技术系统分析了厌氧消化中细菌与古细菌的群落结构,测序结果表明,整个过程中拟杆菌(Bacteroidetes)、甲烷鬃菌(Methanosaeta)及甲烷螺菌(Methanospirillum)为优势微生物,随着负荷的提高,甲烷鬃毛菌(Methanosaeta)活性逐渐降低;聚类分析及主成分分析表明,低负荷条件下(1.50g·L-·1d-1、1.75g·L-·1d-1),微生物种类(细菌、古细菌)差别不明显,且基本处于同一阶段.     

Nitrogen deposition alters soil chemical properties and bacterial communities in the Inner Mongolia grassland

Nitrogen deposition has dramatically altered biodiversity and ecosystem functioning on the earth; however, its effects on soil bacterial community and the underlying mechanisms of these effects have not been thoroughly examined. Changes in ecosystems caused by nitrogen deposition have traditionally been attributed to increased nitrogen content. In fact, nitrogen deposition not only leads to increased soil total N content, but also changes in the NH₄⁺-N content, NO₃^--N content and pH, as well as changes in the heterogeneity of the four indexes. The soil indexes for these four factors, their heterogeneity and even the plant community might be routes through which nitrogen deposition alters the bacterial community. Here, we describe a 6-year nitrogen addition experiment conducted in a typical steppe ecosystem to investigate the ecological mechanism by which nitrogen deposition alters bacterial abundance, diversity and composition. We found that various characteristics of the bacterial community were explained by different environmental factors. Nitrogen deposition decreased bacterial abundance that is positively related to soil pH value. In addition, nitrogen addition decreased bacterial diversity, which is negatively related to soil total N content and positively related to soil NO₃^--N heterogeneity. Finally, nitrogen addition altered bacterial composition that is significantly related to soil NH₄⁺-N content. Although nitrogen deposition significantly altered plant biomass, diversity and composition, these characteristics of plant community did not have a significant impact on processes of nitrogen deposition that led to alterations in bacterial abundance, diversity and composition. Therefore, more sensitive molecular technologies should be adopted to detect the subtle shifts of microbial community structure induced by the changes of plant community upon nitrogen deposition.     

Responses of plant, insect and spider biodiversity to local and landscape scale management intensity in cereal crops and grasslands

The aim of this study was to determine the relative effects of landscape scale management intensity, agroecosystem type, local management intensity and edges on diversity patterns of functional groups of plants, carabid beetles, spiders and grasshoppers. Nine landscapes were selected differing in percent intensively used agricultural area (IAA), each with a pair of organic and conventional winter wheat fields and a pair of organic and conventional mown meadows. Within fields, plants were surveyed in the edge and in the interior. Carabid beetles and spiders were captured by funnel traps, while grasshoppers were sweep-netted in the meadows. Diversity patterns of study organisms were affected both by local variables (local management, agroecosystem type and within-field position) and by landscape scale management intensity. Species richness of grasses, presumably because of sowing low-diversity mixtures, and hunting spiders decreased with percent cover of IAA. Meadows differed from wheat fields in that they had higher species richness of forbs and grasses, as well as higher densities of hunting spiders. In contrast, more carabid individuals, especially of non-carnivore species, were captured in wheat fields. In field edges with their reduced management intensity and increased immigration, species richness of plants, carabids and spiders was higher than in the interiors regardless of agroecosystem type and management. Organic management enhanced forb richness and cover in both agroecosystem types. Organic management also increased grass cover in wheat fields, but not in meadows, and promoted species richness of non-carnivore carabids and hunting spiders, but not grasshoppers. The results show that agri-environmental management needs to be targeted to the agroecosystem's field size, because higher edge area led to higher species richness. Organic management affected several functional groups positively (forbs, non-carnivore carabids, hunting spiders), while lower landscape scale management intensity only increased species richness of grasses and spiders. The great differences in responses of functional groups to local cereal and grassland as well as landscape management suggest implementing more scale and group specific targets for agri-environmental schemes to improve their efficiency.     

超声波促进好氧/缺氧污泥消化过程中细菌群落结构分析

应用基于16S rDNA的PCR-DGGE对超声波-好氧/缺氧污泥消化过程中微生物种群的多样性进行研究.通过SDS细胞裂解法提取不同时期污泥中的基因组DNA,采用通用引物进行V3区域PCR扩增,长约190 bp的PCR产物经DGGE分离后,获得污泥微生物群落的DNA特征指纹图谱,对条带进行切胶测序,使用序列数据进行同源性分析并建立系统发育树.DGGE图谱表明,在反应器运行的不同时期,微生物群落结构发生动态演替.5、10、15、20、25 d微生物相似性与0 d相比分别为61.2%、48.2%、46.4%、42.6%、41.7%,总细菌Shannon指数经历了一个从逐渐减少到趋于稳定的过程,这表明超声波改变污泥内部性质,导致微生物多样性的降低.UPGMA聚类分析将DGGE图谱区分为三大族群并对应于不同运行时期.测序结果表明,超声波-好氧/缺氧污泥消化中微生物群落主要为Firmicute、Genuscitrobacter、Bacilli、α-Proteobacteria、β-Proteobacteria.     

若尔盖高原湿地藻类多样性研究

分别于夏、冬两季采集若尔盖高原湿地水样,利用传统培养及显微镜检的方法和现代分子生物学方法对其藻类多样性进行了研究.结果表明,夏季水样至少培养出4种绿藻,分别为普通小球藻(Chlorella vulgaris Beij.)、浮球藻(Planktosphaeriagelatinosa G.M.Smith)、繁茂栅列藻(Scenedesmus abundans Kirchner)和柱状栅列藻(Scenedesmus bijuga Turp.),均属于绿球藻(Chlorococcales),其中普通小球藻为优势藻种,并被分离纯化.显微镜检结果表明冬季水样中主要的藻类种群为硅藻,此结果符合在低温季节天然水体中常以硅藻为主的常理.蓝藻16S rRNA基因克隆文库中的主要类群为硅藻(Bacillaripiophyta,35.3%),其次为蓝藻,包括色球藻(Chroococcales,5.9%)、念珠藻(Nostocales,11.8%)、颤藻(Oscillatoriales,11.8%)和一些未知种属的蓝藻类群(Unclassified Cyanobacteria,35.3%),还发现一些与低温环境微生物相关的类群,如颤藻目细纤菌属(Leptolyngbya).