青海湖沉积柱Dinoflagellate藻类基因丰度变化及其古气候环境的指示意义

近年来,有学者通过古DNA方法成功地重建了海洋沉积记录中古微生物群落变化,并借此反演了当地古环境-气候变化。然而,此种方法对于陆地湖泊沉积记录是否适用仍然有待研究。本文采用聚合酶链式反应（PCR, Polymerase Chain Reaction）、变性梯度凝胶电泳（DGGE,Denaturing Gradient Gel Electrophoresis）与实时荧光定量聚合酶链式反应（Q-PCR,Quantitative PCR）相结合的综合分析技术手段,系统研究青海湖5.8米（时间跨度为～18500年）沉积柱dinoflagellate真核藻类多样性和丰度变化。研究结果显示青海湖Dinoflagellate藻18S rRNA基因序列主要与海洋型藻类Woloszynskia halophila和Scrippsiella hangoei相近（～98%序列相似性）。定量Q-PCR结果显示,每克沉积物含有dinoflagellate藻类18S rRNA基因丰度范围为2.27×103～8.55×106拷贝。另外,Dinoflagellate藻类18S rRNA基因丰度与总有机碳含量成显著正相关（r = 0.408,p = 0.0001）。对比分析揭示较高的藻类丰度对应高总有机碳含量和较低的可溶解性盐电导率;反之,较低的藻类丰度对应较高的可溶解性盐电导率和较低的总有机碳含量。在青海湖区,总有机碳指示着季风降雨变化并间接地指示着外源输入和湖泊营养状况变化,然而可溶性盐电导率则指示着湖泊盐度变化。综上所诉,青海湖沉积柱Dinoflagellate藻类丰度可能响应着历史时期湖泊营养状况和盐度波动情况。     

青海湖1.8万年以来甲藻Dinoflagellate群落变化及其古气候环境的指示意义

近年来,有学者通过古DNA方法成功地重建了海洋沉积记录中古微生物群落变化,并借此反演了当地古环境—气候变化。然而,此种方法对于陆地湖泊沉积记录是否适用仍然有待研究。采用聚合酶链式反应(PCR,Polymerase Chain Reaction)、变性梯度凝胶电泳(DGGE,Denaturing Gradient Gel Electrophoresis)与实时荧光定量聚合酶链式反应(Q-PCR,Quantitative PCR)相结合的综合分析技术手段,系统研究青海湖5.8 m(时间跨度为~18 500 a)沉积柱中的甲藻(Dinoflagellate)多样性和丰度变化。研究结果显示,青海湖Dinoflagellate藻18S rRNA基因序列主要与海洋型藻类Woloszynskiahalophila和Scrippsiellahangoei相近(~98%序列相似性)。定量Q-PCR结果显示,每克沉积物含有dinoflagellate藻类18S rRNA基因丰度范围为2.27×10~3~8.55×10~6拷贝。另外,Dinoflagellate藻类18S rRNA基因丰度与总有机碳含量成显著正相关(R=0.408,p=0.0001)。对比分析揭示,较高的藻类丰度对应高总有机碳含量和较低的可溶解性盐电导率;反之,较低的藻类丰度对应较高的可溶解性盐电导率和较低的总有机碳含量。在青海湖区,总有机碳指示着季风降雨变化,并间接地指示着外源输入和湖泊营养状况变化,然而可溶性盐电导率则指示着湖泊盐度变化。综上所述,青海湖沉积柱Dinoflagellate藻类丰度可能反应了历史时期湖泊营养状况和盐度波动情况。     

湿地土壤硫酸盐还原菌的分子检测及其与植物的相互作用

硫酸盐还原菌(SRB)是一类利用硫酸盐作为末端电子受体进行有机物降解的厌氧微生物,在湿地土壤硫循环和碳循环中发挥着极其重要的作用。分子检测方法弥补了传统基于培养的检测方法的不足,可以充分描述湿地土壤硫酸盐还原菌的多样性,为硫酸盐还原菌的多样性检测提供了一种更为精确和科学的工具。在有植被的湿地土壤中,特别是根际土壤中,硫酸盐还原菌与湿地植物之间存在着相互影响的复杂关系。综述了湿地土壤硫酸盐还原菌分子检测中两类重要的标记基因,硫酸盐还原菌定性和定量分子检测方法,包括末端限制性片段长度多态性(T-RFLP)、变性梯度凝胶电泳(DGGE)、实时定量PCR(real-time q PCR)和荧光原位杂交(FISH),同时对硫酸盐还原菌与湿地植物之间相互作用的研究进行了总结,提出该领域今后应该深入研究的一些问题及建议。     

青藏高原北部湖泊沉积物中基于不同碳源可培养细菌多样性

前人研究显示微生物群落对有机碳源的利用具有选择性,但是纯菌株对碳源利用的选择性却不甚明了。此外,在盐湖环境中微生物出于能量的考虑可能选择性利用有机碳源以抵抗盐度渗透压。因此,盐度可能间接地影响微生物对有机碳源的利用。然而,目前类似的相关研究较少。采用单碳源纯培养技术、16S rRNA基因序列分析和相关统计方法,研究了青藏高原北部6个湖泊(洱海、青海湖、托素湖、尕海1、尕海2、小柴旦湖)沉积物中基于不同碳源可培养细菌多样性及其与盐度的响应关系。采用7种不同类型的单碳源(甲酸钠、乙酸钠、丙酮酸钠、乳酸钠、葡萄糖、纤维素、混合氨基酸)进行培养筛选。共获得10个细菌分类属的75株纯培养菌株,它们分属于γ-变形菌纲的气单胞菌属(Aeromonas)、盐单胞菌属(Halomonas)、希瓦氏菌属(Shewanella)、假单胞菌属(Pseudomonas)、假交替单胞菌属(Pseudoalteromonas)、弧菌属(Vibrio),β-变形菌纲的脱氯单胞菌属(Dechloromonas)以及芽孢杆菌纲的芽孢杆菌属(Bacillus)、微小杆菌属(Exiguobacterium)和游动球菌属(Planococcus)。其中,盐单胞菌属菌株可利用研究中使用的所有碳源类型,说明这类细菌具有广泛碳代谢途径,可能潜在参与了青藏高原北部湖泊碳循环过程。研究发现所得纯菌株对不同碳链长度碳源的利用具有选择性,即随着盐度增高,某些菌株偏向利用结构更加复杂的碳源。总之,盐度不仅影响着纯培养细菌群落多样性,而且还影响着细菌对碳源类型的选择。     

青藏高原北部湖泊沉积物中基于不同碳源可培养细菌多样性

自然环境溶解有机碳（DOC）的组成影响着微生物群落结构,不同微生物类群对有机碳源类型的利用表现出差异。然而,纯菌株的碳源利用选择性及其和盐度的关系却仍不是很清楚。本文采用单碳源纯培养技术、聚合酶链式反应（PCR,Polymerase Chain Reaction）和相关统计方法,研究了青藏高原北部六个湖泊（洱海、青海湖、托素湖、尕海1、尕海2、小柴旦湖）沉积物中的基于不同碳源可培养细菌多样性及其与盐度的响应关系。采用七种不同类型的单碳源（甲酸钠、乙酸钠、丙酮酸钠、乳酸钠、葡萄糖、纤维素、混合氨基酸）进行培养筛选。本文共获得10个细菌分类属,它们分属于假单胞菌属（Pseudomonas）、气单胞菌属（Aeromonas）、希瓦氏菌属（Shewanella）、脱氯单胞菌属（Dechloromonas）、动性球菌属（Planococcus）、盐单胞菌属（Halomonas）、微小杆菌属（Exiguobacterium）、弧菌属（Vibrio）、交替假单胞菌属（Pseudoalteromonas）和芽孢杆菌属（Bacillus）。其中,盐单胞菌属菌株可利用本研究使用的所有碳源类型,说明这类细菌具有广泛碳代谢途径,并潜在地参与了青藏高原北部湖泊碳循环过程。所得的纯菌株利用不同碳链长度的碳源具有选择性,即随着盐度增高,某些菌株更偏向利用结构更加复杂的碳源。总之,盐度不仅影响着纯培养细菌群落多样性,而且还影响着细菌对碳源类型的选择。     

艾比湖原核微生物菌群结构演变与环境因子关系分析

用非培养法获得新疆维吾尔自治区艾比湖湖底沉积物原核微生物菌群组成,并与已有盐湖原核微生物菌群数据进行比对,分析湖泊由淡水湖向盐湖演替过程中原核微生物群落结构变化规律。实验获得艾比湖原核微生物16S rRNA基因序列,并从NCBI数据库下载赛里木湖、柴窝堡湖和顿巴斯他乌盐湖3个湖泊的非培养原核微生物16S rRNA基因序列数据。用不同盐湖细菌和古菌16S rRNA序列信息构建系统发育树并与其理化指标进行典型性相关分析。同源比对及聚类结果显示,艾比湖湖底沉积物中细菌包括4个门,拟杆菌门(Bacteroidetes)占克隆文库的64%,变形菌门(Proteobacteria)占9.4%,厚壁菌门(Firmicutes)占3.4%,放线菌门(Actinobacteria)占2.6%,此外含有未分类类群20.6%。古菌含有两个门,广古菌门(Euryarchaeota,98.3%)和盐纳古菌门(Nanohaloarchaeota,1.7%)。不同盐湖系统发育树结果显示,随盐度增加,盐湖细菌从变形菌门向拟杆菌门演替;古菌从奇古菌门和泉古菌门向广古菌门和盐纳古菌门演替。RDA结果显示,Na⁺、Cl-、SO₄2-和矿化度对盐湖原核微生物多样性结构起到决定性的作用,K⁺、Mg²⁺和Ca²⁺对艾比湖菌群结构影响作用最为显著。原核微生物群落会随着湖水盐浓度的增加和盐湖化学成分的不同而发生演替。     

白令海和楚科奇海总好气异养细菌丰度和对温度的适应性

用平皿培养计数法测定了白令海和楚科奇海测区水和沉积物中的总好气异养细菌(GAB)的丰度 ,并进行了比较。分析了不同海区、测点、不同层次沉积物中GAB丰度及在不同温度中的适应性。结果表明 ,水中GAB检出率大于沉积物 ,但丰度仅为后者的 0 .0 7% ;表层沉积物中GAB检出率高于其它层次 ;白令海GAB检出率、丰度及变幅均高于楚科奇海。所有站点沉积物中GAB含量平均约为 31 66.3× 1 0 2 CFU·g- 1 (湿 ) ;沉积物GAB丰度大致显出低纬度区大于高纬度区之势。温度试验结果表明所试GAB中多数为适冷菌 ,少数可能为中温菌 ,显示出北极海洋细菌对温度有较强的适应性     

2011年夏季北极王湾细菌群落结构分析及浮游细菌丰度检测

采用PCR-DGGE方法,对2011年夏季北极王湾表层海水及沉积物细菌的群落分析结果表明,沉积物中的细菌多样性指数高于海水。深水站位(S1和S3)的沉积物细菌群落不但与浮游细菌群落存在差异,并且与浅水站位(S5)也存在差异。位于湾口、湾内的浮游细菌群落组成也存在一定差异。测序结果显示,王湾海洋细菌的多样性组成包括α-变形细菌、γ-变形细菌、δ-变形细菌、放线菌、拟杆菌及厚壁菌等类群。基于定量PCR方法的检测结果表明,位于湾口、湾内的浮游细菌丰度相似,但湾内玫瑰杆菌支系的丰度明显低于湾口。研究结果表明,与湾口相比,王湾湾内的细菌群落受陆源性淡水输入的影响明显,不但表现在细菌群落的多样性组成上,也表现在某些特定细菌类群的数量分布上。     

椒江化工园区附近潮间带沉积物中微生物群落结构及其对环境因子的响应

为了研究滨海化工园区附近潮间带沉积环境中的微生物群落结构,揭示化工园区排污对附近沉积环境中微生物的多样性及群落影响,同时也为揭示滨海化工园区附近潮间带环境中微生物群落的多样性和复杂性。选择浙江省台州市椒江化工园区附近潮间带沉积物微生物群落为研究对象,利用Illumina Mi Seq高通量测序技术,在椒江化工园区附近潮间带的沉积物中,共鉴定出古菌和细菌16门43科76属176种,其中,变形菌门丰度最高,其序列数占总序列数的62.4%;ACE指数和Chao指数的平均值分别为232和233,Shannon多样性指数平均值为4.44,Simpson多样性指数平均值为0.033,表明潮间带沉积物中微生物群落的多样性水平较高,化工园区南、北端附近潮间带沉积物中微生物群落的多样性水平差异较小;沉积物中绿弯菌门、浮霉菌门物种数量等与多数环境指标显著负相关,装甲菌门、脱铁杆菌门和待定菌群OD2、TM8物种数量则与多种重金属、多环芳烃和多氯联苯化合物含量显著正相关。     

芦苇根际沉积物中溶解性有机物组成及其与铁还原菌关系的实验研究

2019年4月6日至7月4日,在湖南大学环境学院天台大棚中,利用采集到的东洞庭湖洲滩沉积物,种植芦苇(Phragmites australis),在淹水(沉积物表面淹水深度为2 cm)和未淹水(沉积物表面未淹水,其含水量为70%)条件下,开展实验。在实验第30天、第60天和第90天,在花盆中采集沉积物样品,利用傅立叶红外光谱分析技术,研究沉积物样品的溶解性有机物的组成,分析沉积物中铁还原菌的丰度与溶解性有机物的关系。研究结果表明,在实验的90 d中,与天然沉积物相比,芦苇根际沉积物中溶解性有机物的羟基官能团含量减小,羧基官能团含量增大;在实验第30天和第60天,与非根际沉积物相比,芦苇根际沉积物中有机质官能团的积累量更高,而在实验第90天规律相反;沉积物中芽孢杆菌属(Bacillus)、梭菌属(Clostridium)的相对丰度低于厌氧粘细菌属(Anaeromyxobacter)、地杆菌属(Geobacter);溶解性有机物中官能团含量受培养时间、淹水条件和根际环境影响;对溶解性有机物中官能团特征造成主要影响的是发酵铁还原菌。     

南极菲尔德斯半岛表层土壤样品中细菌多样性的系统发育分析

通过PCR结合变性梯度凝胶电泳(DGGE)技术对从南极长城站附近表层土壤样品中获得16SrDNA序列特征片段V3区序列进行分离。对其中的主要12条DGGE条带进行胶回收,获得的DNA片段经测序以及计算机比对分析发现,它们分别属于β、γ、δ-变形细菌(Proteobac-teria)、噬纤维菌-屈挠杆菌-拟杆菌(Cytophaga-Flexibacter-Bacteroides,CFB)群细菌、放线细菌(Actinobacteria)、蓝细菌属(Cyanobacteria)、酸杆菌属(Acidobacteria)和绿屈挠菌属(Chlo-roflexi)等系统分类群。南极表层土壤样品中的大部分16S rDNA序列与从其他土壤或沉积物样品中直接获得的序列相似性较高(93%-100%)。     

Distribution of diatom assemblages and their relationship to environmental variables in the surface sediments of three northern Egyptian lakes

Surficial sediments of three northern Egyptian lakes (Manzala, Burullus and Edku) show differences in diatom assemblages deposited in different sites of these lakes. A total of 172 species and varieties belonging to 58 genera were identified and counted from 62 samples. Of these, 163 diatom taxa were recorded from Manzala Lake sediments, 147 taxa were found in Burullus Lake sediments, and 117 taxa were identified in Edku Lake sediments. The considerable variation in the composition and distribution of the diatom assemblages among these lakes was mainly related to differences in the water quality, salinity, the concentration of nutrients and climatic changes. The planktonic diatom Cyclotella meneghiniana was dominant in the majority of the samples from Manzala Lake, but dominant in only a few samples from the middle parts of Burullus and Edku lakes. The non-planktonic epiphytic taxa Cocconeis placentula and Epithemia sorex were the subdominant species in the surface sediments, especially in shallow and marginal parts of the lakes. Multivariate statistical techniques (hierarchical ascending clustering and canonical correspondence analysis) were used to identify ecological groups of diatoms and to investigate which environmental variables were important in explaining the variation between these groups. Eight ecological groups containing distinctive diatom assemblages reflect current environmental conditions; especially saltwater intrusion in the north and nutrient-rich freshwater in the south.     

不同预处理方法对尕海沉积物粒度测试的影响

湖泊沉积物粒度是研究湖区古环境演化的一个重要代用指标,粒度测量结果与预处理方法密切相关。从柴达木尕海湖岩心钻孔取48个样品,采用五种预处理方法,运用马尔文2000激光粒度仪进行粒度分析。结果显示经过预处理后平均粒径有不同程度的变细。单独加入H2O2除去样品中的有机质后,粒度分散变细最为明显,变幅可达10%左右,单独加入(NaPO3)6或H2O2处理后,>63μm(粗颗粒组分)粒径百分含量降低8个百分点左右。单独加蒸馏水浸泡、单独加HCl除去碳酸盐类胶结物和先后加H2O2、HCl(、NaPO3)6处理这三种方法分散效果不明显。23～33号样品对预处理的灵敏度最差,其他样品灵敏度稍好,但总体上尕海湖沉积物对预处理作用不敏感。对于性质类似的盐湖沉积物粒度测试,本文推荐加H2O2进行预处理。     

Recent rapid salinity rise in three East Antarctic lakes

Research in East Antarctica has shown several recent environmental changes that may be linked to human impacts on climate. In order to detect the influence and context of these changes on coastal aquatic ecosystems we examined lake sediment cores from three lakes in the Windmill Islands, East Antarctica; Beall Lake, Holl Lake and ȁ8Lake Mȁ9. Cores were sectioned at␣2.5 mm intervals. Their diatom species composition was examined to detect changes in lake salinity using a diatom-salinity transfer function, and their algal pigment content was examined to detect photoautotrophic community responses to environmental change. Results showed that Holl Lake originated in a depression exposed by Holocene recession of the continental ice sheet and that Beall Lake and Lake M originated as isolated marine basins formed by changes in relative sea level. A general late Holocene trend of declining lake salinity was evident in all three lakes, interrupted by one short-term high salinity event in Beall Lake. This is consistent with a long-term positive moisture balance. This general decline in salinity has been followed by a remarkable recent rapid increase in salinity in all three lakes in the last few decades. We speculate that this rapid increase in salinity might be linked to changes taking place in the region including feedbacks resulting from decreasing sea ice extent as recorded in the nearby Law Dome ice core, and positive feedbacks in the catchments whereby reduced snow cover has led to decreased albedo, which in turn has caused increased evaporation and sublimation. Collectively these changes have shifted the lakes across a threshold from positive to negative moisture balance. A minor, but not rapid shift in the abundance of diatom pigments relative to pigments from green algae and cyanobacteria was also detected suggesting that some changes in photoautotrophic community composition have occurred. Measurements of modern nutrient levels are also higher than would be expected in Beall Lake and Holl Lake, given the extremely low sediment accumulation rates. This may be associated with a c. 300% increase in the population of Adélie penguins in the Windmill Islands recorded since the 1950s, or may a first signs of a rapid increase in catchment development and associated lake productivity as experienced in Antarctic and Arctic lakes subject to recent rapid regional warming. The most marked feature of the records is the rapid increase in salinity in all three lakes in␣the last few decades, which has occurred in lakes both with and without resident penguin populations.Dominic A. Hodgson and Donna Roberts contributed equally to this work     

Microbial Diversity of the Hypersaline Sidi Ameur and Himalatt Salt Lakes of the Algerian Sahara

Microbial populations within hypersaline lakes often exhibit high activities of photosynthesis, dissimilatory sulphate reduction and other processes and, thus, can have profound impacts on biogeochemical cycles of carbon, nitrogen, sulphur and other important elements within arid lands. To further understand these types of ecosystems, the physicochemical and biological properties of Sidi Ameur and Himalatt Salt Lakes in the Algerian Sahara were examined and compared. Both lakes were relatively neutral in pH (7.2-7.4) and high in salt, at 12% and 20% (w/v) salinity for Himalatt and Sidi Ameur Lakes, respectively, with dominant ions of sodium and chloride. The community compositions of microbes from all three domains (Bacteria, Archaea and Eukarya) were surveyed through the use of 16S and 18S ribosomal gene amplification and clone library clustering using amplified ribosomal DNA restriction analysis (ARDRA) in conjunction with DNA sequencing and analysis. A high level of microbial diversity, particularly among the bacteria of the Himalatt Salt Lake and archaea of Sidi Ameur Lake, was found within these environments. Representatives from all known halophilic bacterial phyla as well as 6 different genera of halophilic archaea were identified. Moreover, several apparently novel phylotypes among both archaea and bacteria were revealed.