短程硝化启动运行中功能菌群变化研究

【目的】短程硝化-厌氧氨氧化是可实现的最短生物脱氮工艺,短程硝化是实现该工艺的重要环节和必要条件。【方法】采用序批式反应器(SBR)来实现短程硝化过程的启动和稳定运行,并对该过程中的相关功能菌群变化进行检测分析。【结果】通过控制低DO浓度(<1 mg/L)和逐步提高氨氮进水负荷,可抑制氨氧化细菌(NOB)菌群增殖并促进亚硝酸氧化菌(AOB)菌群规模显著扩大,实现短程硝化过程的启动和稳定运行。在氨氮进水负荷为0.055 kg/(m3.d)时,平均氨氮去除容积负荷和污泥负荷可达到0.043kg/(m3.d)和0.16 kg/(kg.d),平均亚硝酸盐积累率可达到83.4%。在短程硝化启动和稳定运行过程中,NOB菌群密度从2.0×105CFU/mL降至1.5×104CFU/mL,相对丰度从5.51%降至2.14%;AOB菌群密度从4.5×104CFU/mL增加至1.5×107CFU/mL,相对丰度从0.18%增加至7.25%。【结论】AOB菌群规模的扩大是实现短程硝化和氨氮去除能力提高的主要原因,同时较高的进水氨氮浓度和负荷也会造成亚硝化活性的抑制。     

地衣芽孢杆菌对南美白对虾零水交换养殖系统细菌群落的影响

【目的】地衣芽孢杆菌（Bacillus licheniformis）对南美白对虾（Penaeus vannamei）免疫反应、抗病性和营养的影响已被广泛研究，但零水交换养殖系统下地衣芽孢杆菌对对虾肠道和养殖水环境微生物群落的影响尚不清楚。【方法】通过收集添加地衣芽孢杆菌在饲料或水中后，对虾肠道、池水和池低沉积物样品，通过16S rRNA基因测序和线性判别分析（linear discriminant analysis effect size，LEfSe）进行微生物分析。【结果】结果表明，添加地衣芽孢杆菌对对虾的生长影响较小。此外，添加方式的不同对对虾肠道菌群的影响较小。但添加地衣芽孢杆菌可以有效地改变对虾肠道微生物群落，并改善对虾免疫力。【结论】这些结果有助于全面了解在零水交换养殖系统中，通过饲料和水添加地衣芽孢杆菌后对虾肠道和环境的变化，从而为选择正确的益生菌以及如何添加益生菌维持对虾健康提供基础信息。     

降氨除臭芽孢杆菌的筛选鉴定及其氮素迁移过程

【目的】分离和鉴定一株高效降氨除臭芽孢杆菌,并研究其氮素迁移过程。【方法】采用自行设计的筛选平台,根据菌落形态、生理生化特征及16S rRNA基因序列的系统进化树分析进行菌株鉴定;在好氧和厌氧条件下,以NH4+-N为唯一氮源,通过检测NH4+-N、NO2?-N、NO3?-N和产生的气体浓度,明确菌株在降氨过程中氮素的迁移过程及特点。【结果】筛选出一株高效降氨除臭芽孢杆菌,经生化与分子鉴定为凝结芽孢杆菌;其在好氧条件下将NH4+-N降解为NO3?-N,降解率为98%;同时少量NO3?-N经好氧反硝化作用还原为N2;在厌氧条件下进行了硝化作用,但NH4+-N降解率仅为23.7%,且反硝化过程不明显。【结论】筛选得到的高效降氨除臭凝结芽孢杆菌在好氧和厌氧条件下皆具有异养硝化作用,但厌氧条件下反硝化作用不显著,好氧反硝化作用产生的含氮气体为氮气,其在农业和环保领域具有巨大的产业化潜力。     

反硝化除磷菌筛选及其特性研究

【目的】研究反硝化除磷菌特性。【方法】通过微生物筛选和生物学特性研究方法,从对虾养殖池塘中筛选出多株可在有氧条件下同时具有反硝化除磷功能的菌种。【结果】菌株LY-1可在18 h内将初始量为10 mg/L的亚硝酸盐氮降低至0.04 mg/L,PO43?-P降低至0.05 mg/L。在DO浓度为5.0?5.9 mg/L时,该菌反硝化除磷率近100%。试验选取具有反硝化除磷功能的枯草芽孢杆菌为阳性对照菌,大肠杆菌为阴性对照菌,比较研究了菌株LY-1在不同pH、温度、盐度、PO43?-P浓度、亚硝酸盐浓度时反硝化除磷的强弱,在pH为5?9范围时,该菌亚硝酸盐氮去除率近99%,PO43?-P去除率86%;温度为30°C时,该菌反硝化除磷率近100%;盐度为5‰?15‰、PO43?-P浓度为10 mg/L、亚硝酸盐氮浓度为20 mg/L时,该菌亚硝酸盐氮和PO43?-P去除率均可达99%。【结论】菌株LY-1反硝化除磷性能显著高于对照菌(P<0.05)。通过菌株LY-1形态学观察、生理生化及16S rRNA基因序列分析,初步鉴定为蜡样芽孢杆菌(Bacillus cereus)。     

高亚硝酸盐环境下不同生长速率凡纳滨对虾肠道微生物多样性研究北大核心

【目的】高亚硝酸盐环境中饲养的凡纳滨对虾(Litopenaeus vannamei),在养殖结束时其生长速率和体重往往差异较大。本研究旨在探讨在高亚硝酸盐环境下饲养的对虾生长速率与肠道菌群结构和功能的相关性。【方法】本研究通过收集高亚硝酸盐条件下快速生长对虾(rapidly growing,RG)、正常生长对虾(normally growing,NG)和缓慢生长对虾(slowly growing,SG)的肠道和海水样品,通过16S rRNA基因测序、线性判别分析[line discriminant analysis(LDA)effect size,LEfSe]等进行分析。【结果】发现SG的细菌群落多样性与RG和NG不同。主坐标分析(principal coordinate analysis,PCoA)分析表明,NG的群落组成与RG比SG更相似。通过LEfSe差异分析发现,RG中火色杆菌科(Flammeovirgaceae)、黄杆菌科(Flavobacteraceae)和浮酶菌科(Planctomycetaceae)的丰度较高,而SG中脱硫弧菌科(Desulfovibrionaceae)、希瓦氏菌科(Shewanellaceae)和弧菌科(Vibrionaceae)的丰度显著增加。【结论】本研究发现,在高亚硝酸盐环境下,肠道微生物群落的氮代谢能力是造成对虾不同生长速度的原因。该研究将为虾的工业化养殖提供指导。     

耐高温亚硝酸盐降解菌的分离、鉴定及降低雪茄烟叶亚硝胺的应用

【背景】烟草特有亚硝胺(tobacco-specific nitrosamines, TSNAs)是烟草于调制和发酵阶段产生的一类致癌物质,由烟草生物碱与氮氧化物发生亚硝化反应生成,生物碱和亚硝酸盐是TSNAs的直接前体物质。【目的】发掘适用雪茄高温发酵且显著降低TSNAs形成与积累的微生物。【方法】以TSNAs前体物质亚硝酸盐的高效降解为目标,对从雪茄烟叶分离得到的烟草源微生物菌株进行高温培养、亚硝酸盐降解及亚硝酸盐耐受能力研究,得到可于50℃高效降解亚硝酸盐及耐受高浓度亚硝酸盐的微生物菌株,将菌株应用于雪茄烟叶高温发酵35 d,对发酵前后亚硝酸盐、TSNAs、常规化学成分和中性香味成分含量进行测定,分析菌株在雪茄烟叶发酵中对TSNAs含量及烟叶品质的影响。【结果】获得了3株于50℃高效降解亚硝酸盐的菌株NY7、NY8和NY9,分别鉴定为莫海威芽孢杆菌(Bacillus mojavensis) NY7、耐盐芽孢杆菌(Bacillus halotolerans) NY8和枯草芽孢杆菌(Bacillus subtilis) NY9,其中B. halotolerans NY8亚硝酸盐降解能...     

典型对虾养殖水体中参与硝化与反硝化过程的微生物群落结构

【目的】本研究旨在分析典型虾塘养殖水体中参与氮循环关键过程的菌群多样性,为指导实际对虾养殖水体中NH 4+和NO 2-的微生物降解、水体氮素污染控制以及虾塘养殖氮素循环的有效管理提供科学依据。【方法】使用聚合酶链式反应及变性梯度凝胶电泳技术(Polymerase Chain Reaction-Denaturing Gradient GelElectrophoresis,PCR-DGGE)从8个不同地点的虾塘水样中确定代表性水样,以此为典型水样进行研究,构建了氨单加氧酶基因(amoA)、亚硝酸盐氧化还原酶基因(nxrA)、亚硝酸盐还原酶基因(nirS)的克隆文库。利用限制性片段长度多态性(Restriction Fragment Length Polymorphism,RFLP)技术将克隆文库进行酶切分析。【结果】通过序列多态性分析,表明amoA基因克隆文库中所有序列都属于变形杆菌门β亚纲(β-Proteobacteria),分别为亚硝化单细胞菌属(Nitrosomonas)(81%)和亚硝化螺旋菌属(Nitrosospira)(19%)2个属。nxrA基因克隆文库检测到α-Proteobacteria和δ-Proteobacteria两个亚纲,其中硝化杆菌属(Nitrobacter)是优势菌群,占整个文库的92%,仅有一个类群属于δ亚纲的脱硫杆菌科(Desulfobacteraceae)(8%)。nirS基因文库群落结构相对于amoA和nxrA基因文库较复杂,分别为α-Proteobacteria、β-Proteobacteria亚纲和Actinobacteria,序列分析表明,25%的类群为固氮弧菌属(Azoarcus),25%的类群为(Polymorphum),20%的类群为需氧去氮菌属(Thauera),10%的类群为(Sophophora),10%的的类群为链霉菌属(Streptomyces),5%的类群为(Brachymonas),5%的类群为(Ruegeria)。【结论】典型虾塘养殖水环境中氮素循环关键过程的菌群多样性丰富,其中亚硝化单胞菌属(Nitrosomonas)和硝化杆菌属(Nitrobacter)分别是此环境中主要的氨氧化作用推动者和亚硝酸盐氧化作用推动者,而在反硝化重要环节中,固氮弧菌属等多种菌群都起着推动作用。     

4种理化因子对菌株XH1硝化效果的影响

【背景】基于硝化菌群的富集培养技术可高效稳定地去除养殖水体中的有害氮素,而当前在水产养殖领域有关硝化菌群定向培育及硝化功能菌株的研究较少。【目的】研究不同盐度、pH、温度、通气量条件下硝化菌群分离菌株XH1的生长及其对氨氮和亚硝氮的去除效果。【方法】设置不同梯度的盐度、pH、温度、通气量条件,通过计数菌量、测定氨氮及亚硝氮的浓度变化,比较不同条件下菌株XH1的生长及其对氨氮和亚硝氮的影响。【结果】菌株XH1可在盐度5‰-35‰、pH 6.0-9.0、温度15-45°C和通气量0.5-1 V/(V·min)的条件下生长良好,菌量最高可达2.34×109cells/mL;在盐度5‰-35‰、pH 6.0-9.0、温度15-30°C、通气量0.5 V/(V·min)的条件下,对氨氮的去除效果显著(P0.05),在第1-3天对培养液中氨氮的最高去除率可达86%-97%,但培养液中的氨氮浓度先降后升;对亚硝氮的最高去除率达68%。【结论】菌株XH1对盐度、pH、温度等主要环境因子具有良好的适应性,其对水体氨氮的去除效果良好,可作为中低盐度养殖池塘水体氨氮防控菌剂产品研发的备选菌株。     

一株高效异养硝化菌的选育、鉴定及其硝化条件

【目的】针对现阶段异养硝化菌硝化速率较低的问题,选育更高效的异养硝化菌,进而鉴定该菌株的种属,了解其硝化特性和硝化条件。【方法】分别从污水处理厂活性污泥、化肥厂土壤以及农田土壤中取样,以柠檬酸钠为碳源,NH4Cl为氮源,采用污泥驯化、驯化过程中驯化液连续梯度稀释、平板划线分离及颜色指示剂快速硝化效果检测等步骤,筛得一株高效的异养硝化菌。经生理生化和16SrDNA序列的系统发育分析鉴定其种属;将该菌接入人工氨氮废水,定时检测水中含氮化合物的变化,了解其硝化特性;通过改变培养基碳源、溶氧量、C/N比、温度和pH考察其硝化条件。【结果】获得的高效异养硝化菌为革兰氏阴性杆菌,不利用葡萄糖发酵,氧化酶、接触酶阳性,不产吲哚,能由有机酸盐产碱;其与产碱菌属菌株Alcaligenessp.ES-SDK-3的16SrDNA同源性高达99.7%。用该菌株处理初始氨氮浓度为182.30mg/L的废水,30h后氨氮去除率为99.8%,指数期平均氨氮去除速率为9.61mg-N/L/h,其在硝化过程中几乎没有亚硝酸盐氮和硝酸盐氮产生;最佳碳源为柠檬酸钠;高的溶氧量和高的C/N比有利于其降解氨氮,当C/N比为12时即可达到较好的效果;该菌株在温度为30℃-35℃,pH为5.0-9.0范围内均能较彻底地降解氨氮。【结论】该菌株为产碱菌属,命名为Alcaligenessp.HN-S;其在硝化速率与处理的氨氮浓度方面均高于目前国内外筛出的大多数异养硝化菌;通过考察其硝化条件,为其走向实际污水脱氮工艺提供了依据。     

氨氮降解菌的筛选、鉴定与复合菌水质调控效果研究

为寻找高效降解水体中氨氮的菌株并对其进行应用评价,研究从多种水产养殖池塘水体和底泥的混合物中筛选出2株氨氮降解菌,降解率分别达97.8%和98.5%,经鉴定均为凝结芽孢杆菌(Bacillus coagulans)。对筛选出的2菌株培养条件进行优化,2菌株pH、C/N适应范围广,并且耐高温、高盐。通过灌服试验表明所筛选菌株对养殖动物是安全的。在此基础上,将筛选菌株与本实验室前期诱变菌株B38复配后制成复合菌,通过养殖试验评价了复合菌对氨氮、亚硝酸盐及藻类数量的调控效果。与4种商品微生态制剂(光合细菌、酵母菌、强效EM和芽孢杆菌)相比,泼洒复合菌的池塘氨氮含量逐渐降低。在氨氮含量下降的同时,亚硝酸盐含量有上升的趋势,但在试验的第18天,复合菌组与酵母菌组亚硝酸盐含量有所降低。对藻类数量的影响结果显示,从第9天开始添加复合菌与芽孢杆菌组藻类数量高于其他各组,在第14天,这2组藻类数量大约为其他组的2倍。由此可见,复合菌具有明显的降氨氮特性,并能有效增加藻类数量,但对亚硝酸盐降解效果不显著。研究为复合型微生态制剂的开发提供了技术支撑。     

六种藓类植物茎的比较解剖学研究

通过对6种藓类植物,即褶叶青藓(Brachythecium salebrosum(Web.et Mohr.)B.S.G.)、湿地匐灯藓(Plagiomnium acutum(Lindb.)Kop.)、侧枝匐灯藓(Plagiomnium maximoviczii(Lindb.)Kop.)、大凤尾藓(Fissidensnobilis Griff.)、大羽藓(Thuidium cymbifolium(Doz.et Molk.)B.S.G.)和大灰藓(Hypnum plumaeforme Wils.)嫩茎和老茎的石蜡切片和显微观察发现,同一藓类植株的嫩茎和老茎,茎结构稳定,不同种藓类植物茎横切面具有不同特征.植物体茎横切面形状、表层细胞的层数、细胞大小和细胞壁厚薄、皮层细胞大小和形状、中轴的有无以及比例等特征可以作为藓类植物的分科分类依据之一.     

Photoregulation of seed germination of wild-type and of an aurea-mutant of tomato

Seed germination of an aurea mutant of tomato ( Lycopersicon esculentum Mill.) is promoted by continuous irradiation with red, far-red or long-wavelength far-red (758 nm) light as well as by cyclic irradiations (5 min red or 5 min far-red/25 min darkness). Far-red light applied immediately after each red does not change the germination behaviour. Seed germination of the isogenic wild-type, cv. UC-105, is promoted by continuous and cyclic red light while it is inhibited by continuous and cyclic far-red light and by continious 758 nm irradiation. Far-red irradiation reverses almost completely the promoting effect of red light. The promoting effect (in the aurea mutant) and the inhibitory effect (in the wild-type) of continuous far-red light do not show photon fluence rate dependency above 20 nmol m⁻² s⁻¹. It is concluded that phytochrome controls tomato seed germination throgh low energy responses in both the wild type and the au mutant. The promoting effect of continuous and cyclic far-red light in the au mutant can be attributed to a greater sensitivity to P_fr.     

Cause of Senescence of Nine Sorts of Flowers

The levels of endogenous phytohormones and respiratory rate in nine sorts of flowers such as Cymbidium faberi Rolfe, Nopalxochia ackermannii Kunth and others were investigated both at full bloom and senescence and meanwhile the effect of exogenous phytohormones on prolonging the blossoms and promoting ethylene production were tested. There is a high content of endogenous ethylene in all the long-lived flowere, about 3–16 folds higer than the short-lived ones. There is a high level of ABA at full blooming flowers of short-lived flowers, in which there is no or only some cytokinins in it, but the ratio of CTK (6BA+zeatin)/ABA is smaller(l.7). The endogenous ABA reached a much higher level at senescence in all nine sorts of flowers, so it is reasonable to consider that it is ABA which plays an important role of regulation in controlling flower's senescence. There is a much higher level of GA3 and zeatin in the long-lived flowers which is not demonstrated in the shortlived ones. The respiratory rate is one of the factors controtling the longevity of flowers, but it does not play a decided role. Application of 6BA and zeatin prolongs distinctly orchid’s longevity, however exogenous IAA through the promotive action on ethylene production, evidently extends the longevity of the flowers of the Nopalxochia ackermannii Kunth.     

Interconnection of parameters of regulation system of lipid peroxidation and of morphophysiological parameters of mouse liver

A complex analysis of seasonal fluctuations of the mean group parameters of the system of regulation of lipid peroxidation has been performed in liver of Balb/c mice. Association of lipid characteristics and morphophysiological parameters is studied in the Balb/c mouse liver. An inter-connection is revealed between the liver index and the amount of lysoforms of phospholipids, the scale and character of the interconnection differing essentially depending on proportion of phos-phatidylcholine in mouse liver phospholipids.     

龙胆科药用植物化学成分的研究现状

龙胆科植物在我国的分布范围很广,且多数为药用植物,其多数种属的药用植物,至今其化学成分尚未被系统研究。综述了目前龙胆科药用植物的化学成分的研究现状及一般提取方法,对近年来发现的环烯醚萜及裂环烯醚萜类化合物进行了总结,为本科药用植物的更深入研究提供了参考。     

Physiological characteristics of various species of strains of carboxydobacteria

Seven strains of aerobic carbon monoxide-oxidizing bacteria (carboxydebacteria) when growing on CO as sole source of carbon and energy had doubling times which ranged from 12–42 h. The activity profiles obtained after discontinuous sucrose density gradient centrifugation indicated that the CO-oxidizing enzymes are soluble and the hydrogenases are membrane-bound in all strains examined. The CO-oxidizing enzymes of Pseudomonas carboxydohydrogena, Pseudomonas carboxydoflava, Comamonas compransoris, and the so far unidentified strains OM2, OM3, and OM4 had a molecular weight of 230,000; that of Achromobacter carboxydus amounted to 170,000. The molecular weights of the CO-oxidizing and H₂-oxidizing enzymes turned out to be identical. The cell sonicates were shown to catalyze the oxidation of both CO and H₂ with methylene blue, thionine, phenazine methosulfate, toluylene blue, dichlorophenolindophenol, cytochrome c or ferricyanide as electron acceptors. Methyl viologen, benzyl viologen, FAD⁺, FMN⁺, and NAD(P)⁺ were not reduced. The spectrum of electron acceptors was identical for all strains tested. Neither free formate, hydrogen nor oxygen gas were involved in the CO-oxidation reaction. Methylene blue was reduced by CO at a 1:1 molar ratio. The results indicate that CO-oxidation by carboxydobacteria is catalyzed by identical or similar enzymes and that the reaction obeys the equation CO+H₂OCO₂+2H⁺+2e^- as previously shown for Pseudomonas carboxydovorans.Dedicated to Otto Kandler remembering almost three decades of enjoyable cooperation     

Modulation of allostery of pyruvate kinase by shifting of an ensemble of microstates

Since the introduction of the concepts of allostery about four decades ago, much advancement has been made in elucidating the structure-function correlation in allostery. However, there are still a number of issues that remain unresolved. In this review we used mammalian pyruvate kinase (PK) as a model system to understand the role of protein dynamics in modulating cooperativity. PK has a triosephosphate isomerase (TIM)(α/β)₈ barrel structural motif. PK is an ideal system to address basic questions regarding regulatory mechanisms about this common (α/β)₈ structural motif. The simplest model accounting for all of the solution thermodynamic and kinetic data on ligand-enzyme interactions involves two conformational states, inactive E^T and active E^R. These conformational states are represented by domain movements. Further studies provide the first evidence for a differential effect of ligand binding on the dynamics of the structural elements, not major secondary structural changes. These data are consistent with our model that allosteric regulation of PK is the consequence of perturbation of the distribution of an ensemble of states in which the inactive E^T and active E^R represent the two extreme end states. Sequence differences and ligands can modulate the distribution of states leading to alterations of functions. The future work includes: defining the network of functionally connected residues; elucidating the chemical principles governing the sequence differences which affect functions; and probing the nature of mutations on the stability of the secondary structural elements, which in turn modulate allostery.     

（鱼句）亚科花（鱼骨）型鱼类骨骼系统的比较

对我国花型Hemibarbuspattern鱼类作了骨骼系统比较,结果表明,此类型鱼类脑颅较长,副蝶骨平直或稍弯曲,眶蝶骨腹纵嵴发达(铜鱼Coreius septentrionalis例外),下颞窝和咽突中等大,基枕骨后突发达;脑颅中的上筛骨的后突、侧筛骨的外筛突,蝶耳骨的外突、上耳骨的后突、围眶骨和后颞窝等均有明显的差异;咽颅中的舌颌骨、尾舌骨、鳃盖骨和下咽齿的列数等又有显著的区别;附肢骨骼中的腰带骨、脊椎骨中的复合神经骨和第4椎骨腹侧的悬器等也有不同之处。据此,这些差异和区别可作为属间或种间的分类依据。