沙埋对干旱沙区真藓结皮层细菌群落结构和多样性的影响

作为干旱沙区常见干扰之一的沙埋显著影响着生物结皮的结构和功能,但其内在的生物学机理还不清楚。利用高通量测序技术,通过对0(对照)、0.5(浅层)、2和10mm(深层)沙埋处理后的腾格里沙漠东南缘沙坡头地区真藓(Bryum argenteum)结皮层细菌群落物种组成与丰度的测定,研究了沙埋对真藓结皮层细菌群落结构和多样性的影响。结果表明:(1)共检测到沙坡头地区真藓结皮层细菌38门106纲181属,以放线菌、变形菌、蓝藻、浮霉菌、拟杆菌和酸杆菌等为主(占细菌群落的78.4%—83.0%);(2)PCA分析表明沙埋导致该地区真藓结皮层细菌群落结构组成发生明显改变。无沙埋时,真藓结皮层细菌群落中相对丰度最高的是蓝藻(18.6%),随着沙埋厚度的增加,依次变为变形菌(21.5%,沙埋厚度0.5mm)、浮霉菌(21.5%,沙埋厚度2mm)和放线菌(23.3%,沙埋厚度10mm);浅层沙埋显著增加了真藓结皮层细菌群落中光合菌、固氮菌和产菌丝体细菌等关键功能菌的丰度,但深层沙埋降低了它们的丰度;(3)沙埋显著增加了真藓结皮层细菌群落多样性(P0.05)和物种丰富度(P0.05),0.5mm沙埋后的细菌群落丰富度指数最高,2mm沙埋后的结皮层细菌群落多样性指数最高。揭示了沙埋对干旱沙区真藓结皮层细菌群落结构与多样性的影响,为深入理解沙埋对沙区生物结皮结构和生态功能影响的生物学机制提供了一定的理论依据。     

毛乌素沙地不同类型生物结皮细菌群落差异及其驱动因子

生物结皮在干旱半干旱区具有极为重要的生态功能,细菌是生物结皮中的重要微生物类群,在生物结皮形成、养分循环与调控过程中发挥着关键作用。然而,对于毛乌素沙地生物结皮演替过程中细菌群落多样性和关键环境因子的认识尚不清楚。因此,本文通过q PCR和高通量测序方法调查了毛乌素沙地裸地、藻结皮、地衣结皮和藓结皮之间的细菌丰度和群落多样性,并探究了生物结皮中细菌群落及其与关键环境因子之间的关系。结果表明,随着生物结皮的演替,细菌16S rRNA基因丰度呈显著上升趋势,细菌Chao1、Shannon指数和系统发育多样性呈先降低后增加的模式。生物结皮不同阶段的细菌门、目和属的相对丰度均存在显著差异,在裸地阶段优势细菌类群是拟杆菌门的噬几丁质菌目、放线菌门的红色杆菌目和变形菌门的根瘤菌目;藻结皮和地衣结皮中均以蓝藻门的颤藻目占绝对优势;藓结皮的细菌以拟杆菌门的噬几丁质菌目和变形菌门的根瘤菌目占优势。全磷、全氮、pH和总有机碳是影响土壤细菌群落的关键环境因子。综上所述,生物结皮的演替通过改变土壤理化特性,为细菌群落提供了不同生态位,其中,土壤养分和pH等环境因子对毛乌素沙地生物结皮细菌物种筛选和群落塑造发挥...     

火电厂周边不同生物结皮细菌群落特征差异及其影响因素

为探究大气降尘重金属污染对矿区周边不同类型生物结皮细菌群落结构的影响,利用高通量测序技术分析位于宁东能源化工基地典型火电厂周边的3类生物结皮(藻结皮ZB、混生结皮HB、苔藓结皮TB)和对照(CK,裸土)的细菌丰度和群落结构,并探讨了影响细菌群落结构的环境因子。结果表明: 不同类型生物结皮的理化性质和重金属含量存在差异,且由于生物结皮对大气降尘重金属的富集作用造成各类结皮均达重度污染级别。在相对丰度排名前10的优势细菌门中,芽单胞菌门、蓝细菌门在不同类型生物结皮之间差异显著。细菌群落α多样性由高到低排序依次为CK>TB>HB>ZB。非度量多维排序(NMDS)结果显示,裸土细菌群落与其他3种生物结皮存在明显差异。相关性分析表明,生物结皮演替对细菌群落组成具有显著影响,细菌多样性和组成与pH、养分、重金属含量等密切相关。放线菌门、绿弯菌门相对丰度与pH值呈显著正相关关系,而与全氮(TN)、全磷(TP)、Pb、Zn、Cd均呈显著负相关关系;冗余分析结果表明,TN、pH、TP、有机碳(SOC)是影响3种生物结皮细菌群落α多样性以及一些优势菌群相对丰度的主要土壤环境因子,而重金属Pb、Zn、Cd是影响细菌群落结构的主要重金属元素,对细菌群落数量和多样性有抑制或刺激作用。说明pH、重金属和养分是影响结皮细菌群落组成的关键因子。总体而言,长期的重金属富集作用会对生物结皮的细菌多样性和群落组成产生影响。     

黄土高原水蚀风蚀交错区固氮微生物群落多样性在生物结皮中的演变规律

生物土壤结皮在黄土高原的水土保持、养分补给等方面发挥着重要生态功能。固氮微生物是固氮过程的关键功能群,影响着土壤氮素平衡,然而黄土高原水蚀风蚀交错区严重的水土流失导致土壤养分大量损失,尤其是氮素。该区域生物结皮广泛发育,它们在干旱半干旱区土壤氮素积累过程中起着重要作用。但是该区域生物结皮不同发育阶段中的固氮潜力、固氮微生物群落多样性及其关键环境控制因子尚不清楚。以黄土高原水蚀风蚀交错区为研究区,三种生物结皮类型和裸地对照为研究对象,采用Illumina HiSeq平台对nifH基因扩增产物进行生物信息学分析,揭示了固氮潜力及微生物群落多样性的分布规律。结果表明,生物结皮演替显著影响固氮酶活性、nifH基因丰度和固氮微生物α-多样性,各值均在苔藓结皮最高,显著高于其它演替阶段,且生物结皮层高于结皮下层土壤。在固氮微生物群落组成上,裸地以变形菌门的红螺菌目、酸硫杆菌目和根瘤菌目为主;而在藻结皮、地衣结皮和藓结皮阶段,均表现为蓝藻门的念珠藻目占绝对优势,是固氮微生物的关键类群,其中Trichormus、念珠藻属是优势固氮物种;与藻结皮、地衣结皮相比,藓结皮中念珠藻目的相对丰度显著降低,而变形菌门的红螺菌目、酸硫杆菌目和根瘤菌目的丰度明显上升。除此之外,蓝杆藻属、鱼腥藻属、斯克尔曼氏菌属、瘤胃梭菌属在藻结皮、地衣结皮、藓结皮也占明显优势。念珠藻目以及Trichormus的丰度与固氮酶活性、nifH基因丰度呈显著正相关关系,而与红螺菌目、酸硫杆菌目、梭菌目、根瘤菌目呈显著负相关;Trichormus相关的物种在黄土高原生物结皮氮输入过程中可能发挥着关键作用。生物结皮演替通过改变土壤pH值、有机质、全氮、含水量等理化特征而影响了微生境,通过环境筛选和物种重排作用对固氮微生物群落进行综合调控,其中pH与土壤全氮(TN)发挥着关键作用。     

土壤基质中细物质含量对人工蓝藻结皮形成的影响

利用人工蓝藻结皮进行生态修复是防治沙漠化的有效方法之一，土壤细物质是限制人工蓝藻结皮拓殖和发育的重要因子之一。流沙中细物质含量较低，为了促进人工蓝藻结皮在流沙中的发育，本研究设置细物质和流沙体积比为0∶1、1∶1、2∶1、4∶1和1∶0共5个处理，比较了不同细物质含量人工蓝藻结皮的生长状况。结果表明：随着细物质含量的增加，人工蓝藻结皮的盖度逐渐增大，叶绿素a含量和胞外多糖含量先增大后略有下降。土壤细物质和流沙体积比为4∶1处理下人工蓝藻结皮发育最好，该处理下培养60 d后，人工蓝藻结皮的盖度为70%,叶绿素a含量为17.5μg·cm^-2,松散结合胞外多糖含量为70.0μg·cm^-2,紧密结合胞外多糖含量为175.0μg·cm^-2,糖被胞外多糖含量为200.0μg·cm^-2。在细物质含量较低的条件下增加蓝藻添加量可以促进人工蓝藻结皮的形成和发育(每个培养皿添加0.5 g蓝藻为最优处理)。本研究为人工蓝藻结皮接种体规模化培养提供了新思路。     

腾格里沙漠东南缘不同生物土壤结皮细菌多样性及其季节动态特征

微生物多样性对于生物土壤结皮在沙漠生态系统中改善局部环境以及提升生态功能具有重要作用。本研究对腾格里沙漠东南缘沙坡头地区藻结皮、藓结皮及其下层的四季样品进行了16S rDNA高通量测序, 以期阐明细菌多样性及其在生物土壤结皮演替过程中的季节变化规律。结果表明4种类型样品的细菌丰富度在夏季显著低于其他3个季节。4种类型样品中主要的细菌类群为变形菌门、放线菌门、绿弯菌门、酸杆菌门、蓝细菌门等, 其中变形菌门和放线菌门为优势类群, 夏季时变形菌门的相对多度显著高于春季、秋季、冬季, 且在结皮层中相对多度显著高于结皮下层。放线菌门的相对多度在春季、夏季显著高于秋季、冬季, 且结皮下层相对多度高于结皮层。生物土壤结皮演替过程中细菌多样性及其相对多度季节动态变化表明其对沙漠土壤局部环境的变化作出了响应, 这为深入理解生物土壤结皮在沙漠生态系统中的生态功能提供了微生物多样性数据。     

三峡库区支流蓝藻水华对浮游细菌群落组成的影响

为探究蓝藻水华生消过程对浮游细菌群落组成的影响, 对三峡库区小江支流进行了采样检测, 结果表明小江采样点的水华优势蓝藻主要为水华鱼腥藻和铜绿微囊藻, 水华中期藻细胞密度分别达6.22109和8.77108个/L, 占总生物量的67%和26%。水华中、末期, 浮游细菌群落变化显著。其中, 水华中期主要以玫瑰单胞菌(Roseomona)等属细菌为主, 水华末期则以芽孢杆菌(Bacillus)等属细菌为优势, 且变形菌门(Proteobacteria)及放线菌门(Actinobacteria)细菌相对丰度明显增加, 暗示了细菌群落组成与库区支流蓝藻水华生消变化可能具有相关性。     

金属尾矿库生物土壤结皮的类型及物种组成

为对金属尾矿库生物土壤结皮进行研究, 2016年对湖北省黄石市的两个废弃尾矿库开展了生物土壤结皮调查,并采用空间代替时间的方法来研究结皮发育演替过程中的物种组成及变化。结皮中蓝藻、真菌和苔藓的绝对丰度分别为(0.63—2.01)×108、(0.19—1.53)×108和(0.08—3.34)×107 copies/g DW soil,随着结皮的演替蓝藻和真菌丰度降低,苔藓的丰度增加。从微生物组成来看,从两个尾矿库的生物土壤结皮中共分析出41门的物种,其中变形菌门、蓝藻门、放线菌门、拟杆菌门、绿弯菌门、疣微菌门、酸杆菌门、浮霉菌门、芽单胞菌门及热微菌门是主要组分,它们在不同结皮中累计丰度均达到90%以上。金属尾矿库中的生物土壤结皮物种组成及其变化规律与荒漠化地区类似,蓝藻在其中具有不可替代的作用。研究表明生物土壤结皮在金属尾矿库中广泛分布,同时可以起到增加尾矿库土壤养分的作用,可广泛应用于金属尾矿库的生态修复。     

灵芝不同菌株胞外多糖的单糖组成和抗氧化活性分析

灵芝多糖是药用真菌灵芝的主要活性成分之一。早期研究发现不同灵芝子实体多糖的单糖组成和活性存在差异,但不同灵芝菌株胞外多糖的单糖组成和活性是否有区别仍不清楚。本研究通过液体发酵获得灵芝菌株5.26和5.616的胞外多糖,使用DEAE-cellulose和Sephadex G-200柱色谱分离纯化得到了两种多糖(5.26-2-1和5.616-2-1),并对5.26-2-1,5.616-2-1的单糖组成和抗氧化活性进行了分析。结果表明,5.26-2-1主要由甘露糖、半乳糖醛酸、半乳糖和葡萄糖组成,而5.616-2-1主要由甘露糖、半乳糖和葡萄糖组成。5.26-2-1中葡萄糖的摩尔百分比为63.97%,显著高于5.616-2-1(29.3%),但半乳糖的摩尔百分比为9.34%,显著低于5.616-2-1 (42.78%)。当多糖质量浓度为2 mg/mL时,5.26-2-1的Fe²⁺螯合能力、对1,1-二苯基-2-三硝基苯肼(DPPH)和羟自由基(·OH)的最大清除率分别为71.9%、71.3%和60.8%,显著高于5.616-2-1的值(63.5%、60.4%和51.8%...     

外源氮素调控C/N比对杉木林凋落叶细菌群落结构的影响

为探究不同C/N比对杉木凋落叶分解特性的影响,通过添加外源氮,采用分解袋法,分析林下植被保留和林下植被去除2种林分中不同C/N比值的杉木凋落叶分解300 d时细菌群落结构差异。研究显示：一定范围内,初始C/N比降低有利于杉木凋落叶分解和细菌群落多样性提升,过低的C/N比则具有抑制作用;相比于林下植被去除,林下植被保留管理措施更有利于杉木凋落叶的分解,且细菌群落多样性更高,但当初始C/N比值为20.3时,杉木凋落叶分解所受的抑制作用更为明显;在门水平上,变形菌门、放线菌门和浮霉菌门为杉木凋落叶中主要优势种群;在属水平上,慢生根瘤菌属、嗜酸栖热菌属和Singulisphaera属在杉木凋落叶中相对丰度较高;不同处理间的杉木凋落叶细菌群落结构具有显著差异,变形菌门、放线菌门和酸杆菌门等细菌门中的多类细菌相对丰度差异显著;在门分类水平上,杉木凋落叶C/N比值与主要细菌种群相对丰度的相关性最高,C/P比值与杉木凋落叶细菌群落结构变异的相关性最高;在属水平上,杉木凋落叶全碳含量、C/N比值和全钾含量与主要细菌种群相对丰度的相关性最高,全钾含量与杉木凋落叶细菌群落结构变异的相关性最高。结果表明初始C/N比的降低改变了杉木凋落叶细菌群落结构,进而作用于杉木凋落叶的分解。     

Ecological variations and role of heat shock protein in Artemisia judaica L. in response to temperature regimes of Tabuk,Saudi Arabia

Artemisia judaica L. (Compositae) are shrubby herbs growing wildly in Tabuk region and distributed in the desert regions. This region is characterized by extremely variable environmental conditions where the temperature varies from extreme low to extreme high. These temperature regimes have a profound effect on morphology, growth physiology and biochemistry of the plants. The plant samples were collected from Tabuk–Jordan road (760 m above sea level) in the month of January, April, July and October 2013 to evaluate the effect of temperature dynamics on A. judaica L. in four different seasons. Physiological, biochemical alterations and heat shock proteins (HSPs) were studied during these seasons in order to evaluate the environmental adaptation and stress tolerance in response to temperature variations. Plant growth parameters showed a significant increase in height, fresh and dry matter accumulation, total chlorophyll, nitrogen, phosphorus, potassium, artemisinin and leaf relative water contents investigated in the month of April and October. Growth of plant was suppressed and an active role of carbonic anhydrase (CA), catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) was observed to cope with the extreme low temperature in January and extreme high temperature in July 2013. However, the plants collected in October and April did not show a statistical difference. Inductions in the expression of HSP90 were recorded in all the plants collected during April and October 2013 with no statistically significant difference. Therefore, based on the results it is recommended that during April and October the environmental conditions are best suitable for growth, development and medicinal use of Artemisia.     

Bacterial Community Dynamics During Nursery Rearing of Pacific White Shrimp ( Litopenaeus vannamei ) Revealed via High-Throughput Sequencing

A 20-day trial was conducted to reveal bacterial community dynamics in a commercial nursery of larval Litopenaeus vannamei larvae. The bacterial communities in the ambient water were profiled by high-throughput sequencing of the V4–V5 hypervariable region of the 16S rRNA gene. The results indicated that the dominant bacterial phyla between the metamorphosis stage and postlarval stage were Bacteroidetes, Proteobacteria, Cyanobacteria, and Firmicutes, representing more than 80.09% of the bacterial operational taxonomic units. The relative abundance among bacterial phyla notably differed between the two stages. The relative abundance of Cyanobacteria was higher in the metamorphosis stage, while that of Bacteroidetes was higher and more stable in the postlarval stage. At the class level, the relative abundance of Sphingobacteriia and Alphaproteobacteria increased markedly in the postlarval stage, while that of Flavobacteriia decreased. Redundancy analysis showed that bacterial composition in the metamorphosis stage was positively correlated with salinity, alkalinity, and pH, while in the postlarval stage, it was positively correlated with ammonium nitrogen and nitrite nitrogen. Thus, microbial community diversity in the nursery phase varies per rearing stage.     

海南西部近岸浮游植物的周年变化及主要关联因素

报道了2008—2009年4季度海南西部近岸浮游植物群落的周年动态并探讨其主要关联因素。165份样品经鉴定共有浮游植物4门74属155种(含5变型和2变种),周年平均丰度为(6.36±4.75)×103cells/L。硅藻在物种组成和丰度上均占绝对优势,其次为甲藻,蓝藻(束毛藻)在7月增殖。主要优势种为菱形海线藻(Thalassionema nitzschioides)、奇异棍形藻(Bacillaria paradoxa)、具槽帕拉藻(Paralia sulcata)、旋链角毛藻(Chaetoceros curvisetus)、笔尖根管藻(Rhizosolenia styliformis)、束毛藻(Trichodesmium spp.)、海洋原甲藻(Prorocentrum micans)等。物种组成的季节差异较大,10月浮游植物种类贫乏,1月次之,4月、7月最丰富。丰度10月最高,季节差异并不明显。束毛藻在4月、7月呈斑块状群聚分布。浮游植物周年平均丰度并不高(<1.0×104cells/L)。不同季节优势种有明显的交错和变化,菱形海线藻、奇异棍形藻、具槽帕拉藻为全年优势种。浮游植物物种多样性指数和均匀度都表现出较高的值,均匀度与多样性指数的季节变化特点基本一致,群落多样性高的季节物种均匀度也好。物种多样性指数指示调查区水体遭受污染程度低,水质状况优。调查区各季节的浮游植物丰度与温度之间无显著的相关关系,1月丰度与盐度则呈密切负相关关系。10月浮游植物丰度与无机氮(DIN)呈密切的正相关关系。7月浮游植物丰度与活性磷酸盐(PO4-P)呈密切的负相关关系。浮游动物对浮游植物的摄食压力直接影响到后者的丰度变动,并伴随着海区生态系统的相关复杂现象及生物学过程的作用。     

广州新垦红树林湿地鸟类多样性动态研究

2005年1月(冬季)、4月(春季)、7月(夏季)和10月(秋季),对广州市南沙区新垦红树林湿地区利用样带法进行了鸟类多样性动态研究。广州新垦红树林主要是以人工种植(海桑)为主,研究该湿地鸟类群落多样性,对于红树林生态恢复和物种多样性具有重要意义。在野外调查的基础上对广州新垦红树林鸟类多样性指数(Hˊ)进行了计算,结果表明:1月Hˊ=3.051;4月Hˊ=2.6314;7月Hˊ=2.6867和10月Hˊ=3.0382。该湿地鸟类多样性动态表明出明显的季节性。新垦红树林湿地是广州市鸟类重要的繁殖地和越冬地。     

High Bacterial Diversity of Biological Soil Crusts in Water Tracks over Permafrost in the High Arctic Polar Desert

In this study we report the bacterial diversity of biological soil crusts (biocrusts) inhabiting polar desert soils at the northern land limit of the Arctic polar region (83° 05 N). Employing pyrosequencing of bacterial 16S rRNA genes this study demonstrated that these biocrusts harbor diverse bacterial communities, often as diverse as temperate latitude communities. The effect of wetting pulses on the composition of communities was also determined by collecting samples from soils outside and inside of permafrost water tracks, hill slope flow paths that drain permafrost-affected soils. The intermittent flow regime in the water tracks was correlated with altered relative abundance of phylum level taxonomic bins in the bacterial communities, but the alterations varied between individual sampling sites. Bacteria related to the Cyanobacteria and Acidobacteria demonstrated shifts in relative abundance based on their location either inside or outside of the water tracks. Among cyanobacterial sequences, the proportion of sequences belonging to the family Oscillatoriales consistently increased in relative abundance in the samples from inside the water tracks compared to those outside. Acidobacteria showed responses to wetting pulses in the water tracks, increasing in abundance at one site and decreasing at the other two sites. Subdivision 4 acidobacterial sequences tended to follow the trends in the total Acidobacteria relative abundance, suggesting these organisms were largely responsible for the changes observed in the Acidobacteria. Taken together, these data suggest that the bacterial communities of these high latitude polar biocrusts are diverse but do not show a consensus response to intermittent flow in water tracks over high Arctic permafrost.     

Factors affecting exocellular polysaccharide production by Lactobacillus delbrueckii subsp. bulgaricus grown in a chemically defined medium

We developed a chemically defined medium (CDM) containing lactose or glucose as the carbon source that supports growth and exopolysaccharide (EPS) production of two strains of Lactobacillus delbrueckii subsp. bulgaricus. The factors found to affect EPS production in this medium were oxygen, pH, temperature, and medium constituents, such as orotic acid and the carbon source. EPS production was greatest during the stationary phase. Composition analysis of EPS isolated at different growth phases and produced under different fermentation conditions (varying carbon source or pH) revealed that the component sugars were the same. The EPS from strain L. delbrueckii subsp. bulgaricus CNRZ 1187 contained galactose and glucose, and that of strain L. delbrueckii subsp. bulgaricus CNRZ 416 contained galactose, glucose, and rhamnose. However, the relative proportions of the individual monosaccharides differed, suggesting that repeating unit structures can vary according to specific medium alterations. Under pH-controlled fermentation conditions, L. delbrueckii subsp. bulgaricus strains produced as much EPS in the CDM as in milk. Furthermore, the relative proportions of individual monosaccharides of EPS produced in pH-controlled CDM or in milk were very similar. The CDM we developed may be a useful model and an alternative to milk in studies of EPS production.     

四季桂光合特性的季节变化研究

采用LI-6400光合测定仪测定四季桂光响应曲线和光合特性的季节变化。结果表明,四季桂叶片的光响应曲线变化趋势基本一致,净光合速率和光补偿点由低到高依次为1月< 4月< 10月< 7月,光饱和点依次为7月< 10月< 4月< 1月。四季桂叶片Pn、Tr、VPD、Gs的日变化表现为1月和4月均为单峰曲线,10:00达到峰值;7月和10月均为"双峰型",具有明显的光合"午休"现象。1月,Ci持续下降;4月Ci先逐渐下降,15:00出现小峰值;10月和7月,Ci在10:00最低,15:00达到峰值。     

大伙房水库细菌群落结构及其环境驱动因子研究

为了解大伙房水库生态功能特性和有效改善其水环境质量,2015年5月至2016年4月,在大伙房水库布点采集水样,应用高通量测序技术结合典范对应分析(canonical correspondence analysis,CCA)方法,在为期1年的时间内,研究了该水库4个季节细菌的群落结构及其多样性差异与水体环境因子之间的变化...