Transcriptomes of Litopenaeus vannamei reveal modulation of antioxidant system induced by dietary archaeal carotenoids

Oxidative stress induced by factors such as ammonia nitrogen has become a major issue in shrimp farming.The effects of carotenoids on the growth and antioxidant capability of Litopenaeus vannamei juveniles were investigated in this study using dietary archaeal carotenoids supplementation.For four weeks,shrimp were given diets containing 0 mg/kg(Ctrl)and 55.98 mg/kg(Car)archaeal carotenoids.Dietary archaeal carotenoids significantly enhanced the astaxanthin content in shrimp muscles and carapaces,as well as the superoxide dismutase(SOD)and glutathione peroxidase(GSH-Px)activity(P<0.05).The malonaldehyde(MDA)content in Car group significantly decreased(P<0.05).The transcriptome analysis was conducted to determine the molecular processes in response to archaeal carotenoids supplementation.A total of 1536 differentially expressed genes(DEGs)were detected,including 538 upregulated DEGs and 998 downregulated DEGs.GO functional enrichment analysis between Ctrl and Car indicated that 26 GO terms including extracellular region,metabolic process,and proteolysis were enriched.The KEGG pathway enrichment analysis revealed that the amino sugar and nucleotide sugar metabolism,cysteine and methionine metabolism,glycine serine and threonine metabolism,and amino acid biosynthesis were enriched.Archaeal carotenoids influenced the expression of several important genes involved in reactive oxygen species(ROS)generation,Nrf2 signaling,and antioxidant enzymes.Seven DEGs were chosen to confirm the RNA-Seq data using qRT-PCR.The genes and pathways discovered in this work assist to elucidate the molecular processes through which archaeal carotenoid enhances L.vannamei antioxidative system.

Archaeal community structure in sediments from a seamount in the Mariana Volcanic Arc

Seamounts are subsurface mountains in the ocean. Examination of the abundance and distribution of Archaea in seamount ecosystems may provide a better understanding of their ecological functions. Most studies of marine archaeal assemblages in seamount area have focused on hydrothermal vents or ferromanganese crusts. We investigated the archaeal communities from a seamount of the Mariana Volcanic Arc, in the tropical western Pacific Ocean by using high-throughput sequencing. Thaumarchaeota was dominant in the sediments of all sample stations. Community diversity and species richness were greatest at stations near the top of the seamount, and lowest at the deepest station. One sample station on the steep southeast slope that faced the Yap-Mariana trench had a unique composition of Archaea. In summary, depth has an important influence on archaeal community structure, and the geographic properties and sediment characteristics may explain the unique distribution patterns of Archaea in this seamount. This study provides a foundation for future research on Archaea in seamounts.

Archaeal diversity in the seawater of Changjiang River estuary reveals its adaptability to bottom seawaters

Archaea regulate the biogeochemical processes of ocean systems.The Changjiang(Yangtze)River estuary(CRE) is a complex and dynamic area strongly affected by seawaters and ocean currents.In this study,the planktonic archaeal communities in the surface and bottom seawaters of the CRE were investigated.Significant differences in the archaeal community composition were found between the surface and bottom seawaters(P<0.001).Marine Group Ⅱ(MG-Ⅱ) was dominant in the surface layers,and Nitrosopumilales was enriched in the bottom layers.Marine Group Ⅲ(MG-Ⅲ) was more abundant in the bottom layers than in the surface ones(P<0.001).These results were completely different from previous findings in the CRE seawater.Instead of dissolved oxygen(DO),temperature and salinity were the most vital environmental variations in the distribution of the archacal communities.According to the predicted metabolic pathways,the following functional subcategories were enriched in the hypoxic condition:replication and repair,membrane transport,glycan biosynthesis and metabolism,amino acid metabolism,metabolism of cofactors and vitamins,and xenobiotics biodegradation and metabolism(P<0.001),which indicated the strong adaptability of archaea to the harsh environment in the bottom seawater.These findings expand the understanding on archaeal structure and functions in the surface and bottom seawaters,including the hypoxic zones in the CRE,and may contribute to further works of the archaeal community in the CRE.

Stability Monomolecular Properties of Archaeal Tetraether Lipids Layers onto Solid Substrates

This paper reports the recent findings related to the stability properties of tetraether lipid layers. Organizations moleculars of chemical structure modified of Langmuir-Blodgett layers of archael tetraether lipids from the archebacterium Sulfolobus acidocaldarius on the wafer silicon substrates are investigated stable and organized. The behavior of Langmuir-Blodgett layers of chemical structure modified of archaeal tetraether lipids on the wafer silicon substrates is characterization using Differential Scanning Calorimetry (DSC) and Atomic Force Microscopy (AFM). The thermodynamics behavior and stability of Langmuir-Blodgett layers of archael tetraether lipids on the wafer silicon substrates are shown. Stability of the lipid membranes is of great importance to a number of biomedical applications, including intravenous drug delivery, biomaterials, and biosensors.

连栽对木麻黄人工林根际土壤古菌群落变化的影响

[目的]探究连栽对木麻黄人工林根际土壤古菌群落变化的影响,为探明木麻黄连栽障碍机制提供基础理论依据。[方法]以3个不同连栽代数(第一代First continuous plantation,FCP;第二代Second continuous plantation,SCP;第三代Third continuous plantation,TCP)的木麻黄人工林根际土壤为材料,以未种植木麻黄的天然乔木林根际土壤作为对照(CK),通过Illumina NovaSeq测序平台对古菌群落进行高通量测序。[结果]从3个不同连栽代数木麻黄人工林根际土壤和对照土壤中总共得到1 146 390条有效序列,以100%序列相似度聚类得到998 515个ASV。Alpha多样性分析结果表明,所观察到的物种数和Chao1指数均随着连栽代数的增加呈现下降的趋势,而Shannon指数、Simpson指数和pielou_e均以FCP最高,TCP次之,SCP最低。Beta多样性分析、PCoA分析、UPGMA聚类分析和Anosim分析结果表明,不同连栽代数木麻黄根际土壤古菌群落物种多样性存在差异,但不同组间差异不显著。共检测到5个门,优势菌门为奇古菌门(Thaumarchaeota),且奇古菌门占比随着栽植代数的增加呈现下降的趋势,与对照相比,FCP、SCP、TCP分别下降了17.42%、50.97%、51.51%。古菌群落与土壤理化性质相关性分析结果显示,奇古菌门与pH、全钾(TK)、全氮(TN)、全磷(TP)呈显著正相关,泉古菌门与速效磷(AP)和速效氮(AN)呈显著正相关,不同古菌群落与土壤理化因子之间的相关性存在显著差异。[结论]本研究证实了木麻黄人工林经过多代连续栽植后,根际土壤古菌群落结构发生显著变化,推测古菌群落结构失衡是导致土壤微生态失衡的重要原因之一。研究结果为揭示木麻黄人工林连栽障碍形成的原因提供了理论依据。

Archaeal community structure along a gradient of petroleum contamination in saline-alkali soil

The response of archaeal communities to petroleum contamination in saline-alkali soil was characterized by analyses of three soil samples with different total petroleum hydrocarbon concentrations.Through the construction and screening of 16S rRNA gene clone libraries based on DNA extracts from these soils,nine distinct phylogenetic groups were identified.Statistical analyses showed that the distribution of archaeal community structures differ significantly along the gradient of petroleum contamination in these three saline- alkali soils.Five phylogenetic groups were dominant in the control soil,two of which were also abundant in the lightly contaminated soil.Four phylogenetic groups were dominant in heavily contaminated soil,one of which was also abundant in the lightly contaminated soil.The halophilic genus of Haloferax and the haloalkaliphilic genus of Natronomonas were more abundant in heavily contaminated soil.These results suggested that the genera of Haloferax and Natronomonas may have a role in the natural attenuation of petroleum- contaminated saline-alkali soil.

废弃矿井环境中微生物多样性与代谢功能预测

矿山废水已成为主要的环境污染问题之一,为探究废弃矿井排水生态环境中的微生物群落多样性和功能,选取贵州省遵义市某废弃煤矿,采用16S rRNA基因高通量测序技术研究矿井巷道表层沉积物的细菌和古菌群落组成。结果表明,所有样品中细菌多样性和丰度均高于古菌,细菌群落由52个门820个属组成,其优势菌属主要为A4b科中属水平的未定细菌、SBR1031目中属水平的未定细菌和KD4-96纲中属水平的未定细菌;古菌群落由12个门58个属组成,优势菌门为泉古菌门(Crenarchaeota),优势菌属主要为暂定属Candidatus_Nitrocosmicus和暂定属Candidatus_Nitrsosphaera。PICRUSt2功能预测表明,细菌中包含3条硫代谢循环途径,分别为同化硫酸盐还原、异化硫酸盐氧化/还原和SOX络合物氧化硫代硫酸盐,古菌中包含2条硫代谢循环途径,分别为同化硫酸盐还原和SOX络合物氧化硫代硫酸盐,共检测到18个细菌硫代谢基因和13个古菌硫代谢基因。关于废弃矿井环境中的微生物及其代谢功能分析,能进一步拓展对矿山环境微生物系统的认识。

Temporal changes in soil bacterial and archaeal communities with different fertilizers in tea orchards

It is important to understand the effects of temporal changes in microbial communities in the acidic soils of tea orchards with different fertilizers. A field experiment involving organic fertilizer （OF）, chemical fertilizer （CF）, and unfertilized control （CK） treatments was arranged to analyze the temporal changes in the bacterial and archaeal communities at bimonthly intervals based on the 16S ribosomal RNA （rRNA） gene using terminal restriction fragment length polymorphism （T-RFLP） profiling. The abundances of total bacteria, total archaea, and selected functional genes （bacterial and archaeal amoA, bacterial narG, nirK, nirS, and nosZ） were determined by quantitative poly- merase chain reaction （qPCR）. The results indicate that the structures of bacterial and archaeal communities varied significantly with time and fertilization based on changes in the relative abundance of dominant T-RFs. The abundancy of the detected genes changed with time. The total bacteria, total archaea, and archaeal amoA were less abundant in July. The bacterial amoA and denitrifying genes were less abundant in September, except the nirK gene. The OF treatment increased the abundance of the observed genes, while the CF treatment had little influence on them. The soil temperature significantly affected the bacterial and archaeal community structures. The soil moisture was signif- icantly correlated with the abundance of denitrifying genes. Of the soil chemical properties, soil organic carbon was the most important factor and was significantly correlated with the abundance of the detected genes, except the nirK gene. Overall, this study demonstrated the effects of both temporal alteration and organic fertilizer on the structures of mi- crobial communities and the abundance of genes involved in the nitrogen cycle.

Characterization of the archaeal community fouling a membrane bioreactor

Biofilm formation, one of the primary causes of biofouling, results in reduced membrane flux or increased transmembrane pressure and thus represents a major impediment to the wider implementation of membrane bioreactor （MBR） technologies for water purification. Most studies have focused on the role of bacteria in membrane fouling as they are the most dominant and best studied organisms present in the MBR. In contrast, there is limited information on the role of the archaeal community in biofilm formation in MBRs. This study investigated the composition of the archaeal community during the process of biofouling in an MBR. The archaeal community was observed to have lower richness and diversity in the biofilm than the sludge during the establishment ofbiofilms at low transmembrane pressure （TMP）. Clustering of the communities based on the Bray-Curtis similarity matrix indicated that a subset of the sludge archaeal community formed the initial biofilms. The archaeal community in the biofilm was mainly composed of Thermoprotei, Thermoplasmata, Thermococci, Methanopyri, Methanomicrobia and Halobacteria. Among them, the Thermoprotei and Thermoplasmata were present at higher relative proportions in the biofilms than they were in the sludge. Additionally, the Thermoprotei, Thermoplasmata and Thermococci were the dominant organisms detected in the initial biofilms at low TMP, while as the TMP increased, the Methanopyri, Methanomicrobia, Aciduliprofundum and Halobacteria were present at higher abundances in the biofilms at high TMP.

荒漠孑遗植物沙冬青根部土壤古菌多样性

孑遗植物沙冬青是西鄂尔多斯荒漠生态系统唯一强旱生常绿阔叶灌木。古菌是组成土壤微生物系统的重要组成部分,在土壤生物地球化学循环中扮演着重要角色,影响植物的生长、生产力、适应性、多样性及健康状况。研究与沙冬青根部共存数千万年的土壤古菌群落,对科学保护沙冬青,乃至维持脆弱的西鄂尔多斯荒漠生态系统稳定性有特殊意义。本试验采用16S rDNA扩增子高通量测序技术,以裸地土为对照,分析比较沙冬青根际土、非根际土中古菌多样性及群落物种组成,旨在探明沙冬青根部土壤古菌群落在不同土壤区室中的变化规律。结果表明,与裸地土和非根际土相比,沙冬青根际土中营养元素含量增高;非根际土古菌群落多样性和丰富度均高于根际土和裸地土;奇古菌门亚硝化球菌纲亚硝化球菌科是沙冬青根部土壤优势类群,亚硝化球菌科未分类属(unclassified_f__Nitrososphaeraceae)越靠近根际其相对丰度越高,亚硝化球菌科未定属(norank_f__Nitrososphaeraceae)和暂定亚硝化球菌属(Candidatus_Nitrososphaera)却越靠近根际其相对丰度越低。此外,根际土古菌全部来自非根际土,而非根际土中古菌只有48.8%来自裸地土,其余来自非土壤生境。因此,沙冬青根部土壤古菌群落以参与土壤氮循环氨氧化(亚硝化)过程的类群为主,宿主植物显著影响沙冬青根部土壤不同区室古菌群落组装。

A euryarchaeal histone modulates strand displacement synthesis by replicative DNA polymerases

Euryarchaeota and Crenarchaeota, the two main lineages of the domain Archaea, encode different chromatin proteins and differ in the use of replicative DNA polymerases. Crenarchaea possess a single family B DNA polymerase(Pol B), which is capable of strand displacement modulated by the chromatin proteins Cren7 and Sul7 d. Euryarchaea have two distinct replicative DNA polymerases, PolB and PolD, a family D DNA polymerase. Here we characterized the strand displacement activities of Pol B and Pol D from the hyperthermophilic euryarchaeon Pyrococcus furiosus and investigated the influence of HPf A1, a homolog of eukaryotic histones from P. furiosus, on these activities. We showed that both Pol B and Pol D were efficient in strand displacement. HPf A1 inhibited DNA strand displacement by both DNA polymerases but exhibited little effect on the displacement of a RNA strand annealed to single-stranded template DNA. This is consistent with the finding that HPf A1 bound more tightly to double-stranded DNA than to a RNA:DNA hybrid. Our results suggest that, although crenarchaea and euryarchaea differ in chromosomal packaging, they share similar mechanisms in modulating strand displacement by DNA polymerases during lagging strand DNA synthesis.

Community structure and activity potentials of archaeal communities in hadal sediments of the Mariana and Mussau trenches

Hadal trenches are the least explored marine habitat on earth. Archaea has been shown to be the dominant group in trench sediments. However, the activity potentials and detailed diversity of these communities as well as their inter-trench variations are still not known. In this study, we combined datasets from two pairs of primers to investigate at high resolution the structure and activity potentials of the archaeal communities in vertically sectioned sediment cores taken from the deepest points of the Mariana (10,853 m) and Mussau (7011 m) trenches. The compositions of the potentially active communities revealed, via 16S ribosomal RNA gene (rDNA) and RNA (rRNA), significant differences between samples. Marine Group I (MGI), with nine identified subgroups, was the most dominant class in the active archaeal communities of the two trenches. Significantly different species composition and vertical variations were observed between the two trenches. Vertical transitions from aerobic MGI α to anaerobic MGI η and υ subgroups were observed in MST but not in MT sediments, which might be related to the faster microbial oxygen consumption in MST. These results provide a better understanding on archaeal activity and diversity in trench sediments.

古菌群落视角评估某退役铀尾矿库的治理效果

为了尝试从微生态-古菌群落视角,评估中国西北某铀尾矿库退役治理效果,本研究在前期尾矿库表层覆土0~5 cm和5~15 cm两个垂向剖面放射性核素、重金属/类金属分布特征研究的基础上,通过16S rRNA基因扩增子测序技术对土壤古菌群落进行测序分析,采用生物信息学方法研究铀尾矿库及毗邻区域土壤古菌群落特征及其对环境因子的响应。结果表明:在尾矿库与毗邻区域,尽管土壤中4个优势菌门和3个优势属呈现不均匀分布,但尾矿库内外土壤古菌优势群落结构基本已无显著差异;土壤古菌群落的α多样性(Chao1、ACE和Shannon指数)和β多样性(PCoA)分析显示群落间已不存在差异,群落组成已具有相似性;冗余分析结果表明,土壤pH、TN(总氮)、TOC(总有机碳)、232Th、EC(电导率)是影响优势菌群的主要环境因子,但并未造成库区内外土壤菌群结构的显著改变。尾矿库与毗邻区域的土壤古菌群落已无明显差异,说明尾矿库内外土壤古菌群落并未受到放射性核素、重金属/类金属的显著影响,反映出尾矿库退役治理效果良好。

养殖尾水对河流沉积物中微生物多样性的影响

海产品工厂化养殖是现阶段全球蛋白质供应的主要途径,但其尾水资源化再利用研究不足。因此,本研究通过原位采样和高通量检测技术,分析黄河三角洲永丰河和养殖尾水排水渠中不同样点原位生物群落结构。结果发现,细菌方面永丰河上游与排水渠源头的优势菌属一致,以Gillisia(25.44%~60.35%)和Psychrobacter(4.26%~7.36%)为主;下游和入海口沉积物中主要为Psychrobacter(23.27%~56.73%)和Proteiniclasticum(16.24%~39.58%)。主坐标分析(Principal co-ordinates analysis,PCoA)发现,永丰河与排水渠沉积物中细菌群落间存在一定差异,但差异并不明显。代谢分析发现,排水渠中受到养殖尾水影响有大量有机物亟待处理,导致其中特异性降解的增加,而在入海河口附近,维持渗透压是沉积物中细菌生长的关键。古菌方面,上游沉积物以Candidatus Nitrocosmicus(7.14%~22.98%)和Methanosaeta(13.08%~25.69%)为主;污染源头以Marine Group II(39.38%)为主;下游和入海口沉积物主要是Nitrososphaeraceae(32.70%~78.17%)和Methanogenium(2.19%~11.24%)。PCoA结果表明,样品间的古菌群落有一定的相似性,采样区域的差异并不明显。代谢分析结果表明,古菌更加保守所以更适应于海水渗透压,而且更容易受到有机质输入影响,同时古菌可能参与到芳香族代谢的末端降解过程中。研究结果显示,养殖尾水具有极高的资源化产甲烷的潜力,但其多样的有机碳需要更多的降解菌群参与提高效率。

西藏扎布耶茶卡盐碱湖古菌多样性的非培养技术分析

采用非培养技术 ,直接从西藏扎布耶茶卡盐碱湖样品中提取微生物总DNA。以样品总DNA为模板 ,PCR扩增湖中古菌的 1 6SrDNA序列。扩增产物经过克隆并随机挑选 60个克隆进行测序得到它们的 1 6SrDNA部分序列 ,大部分序列与嗜盐碱古菌的 1 6SrDNA相近。在系统发育树上 ,部分克隆与已知古菌属归于同一分支 ,主要分布在嗜盐菌科的Natronococcus、Natronorubrum、Natronobacterium、Natronomonas、Natrinema、Halorubrum、Haloterrigena和Halorhabdus等 8个嗜盐古菌属中 ,也有一些克隆形成了独立的分支。它们共同显示出扎布耶茶卡湖中的古菌具有丰富的多样性。

浓香型白酒不同窖龄窖池窖泥中古菌群落结构分析

用高通量测序技术对浓香型白酒不同窖龄窖池窖泥中古菌群落结构进行研究,找出其差异性,并利用古菌群落结构信息对不同窖龄窖泥进行聚类分析,同时分析环境因子对各个窖龄段窖泥古菌的影响。结果表明,窖泥中的古菌群落主要分布于Euryarchaeota(占99%OTU数目),分布于7个属;窖泥中古菌的多样性与窖龄呈负相关,Methanobacterium和Methanocorpusculum的优势度与窖龄呈正相关,Thermoplasmatales的优势度与窖龄呈负相关;5 a窖龄的不同窖池窖泥和100 a窖龄不同窖池窖泥微生物群落相似性较高,30 a窖龄的不同窖池窖泥微生物群落差异性较大,对各窖龄段窖泥中古菌群落影响最大的环境因子各不相同。浓香型白酒不同窖龄窖池窖泥古菌群落结构差异性明显,这可能是不同窖龄窖池发酵产酒存在差异性的重要原因之一。

稻田土壤古菌群落组成对秸秆还田的响应

为探讨秸秆还田下稻田土壤古菌群落的演替规律及其驱动因子,本研究开展室内稻田土壤淹水培养试验,利用高通量测序技术,研究了淹水培养第0、15、30 d和60 d时不同量小麦秸秆(0、1%、2%和5%)施用下两种类型的稻田土壤(高砂土和黄泥土)古菌群落组成的动态变化及其影响因子。结果表明:秸秆还田导致土壤pH显著降低,而土壤电导率(EC)、总碳(TC)、总氮(TN)、碳氮比(C/N)以及土壤孔隙水中溶解性有机碳(DOC)、还原性亚铁[Fe(Ⅱ)]和总铁(Fe)含量显著增加,并且当秸秆还田量为5%时,上述土壤指标改变量最大。基于高通量测序技术发现,两种类型稻田土壤的优势古菌均为奇古菌门(Thanumarchaeota)。在淹水培养的0～30 d,秸秆还田对奇古菌门的相对丰度没有显著影响,维持在97%～98%;然而,在培养的第60 d,与未施用秸秆相比,秸秆施用下两种类型稻田土壤中奇古菌门的相对丰度显著降低(P<0.05),并且随着秸秆施用量的增加,奇古菌门丰度的降低程度越大。主成分分析(PCA)结果显示两种不同类型土壤的古菌群落存在着显著差异(P<0.05),表明土壤类型是土壤古菌群落结构的重要影响因子。与未施用秸秆的土壤相比,5%秸秆施用显著改变了高砂土古菌群落结构,而1%秸秆施用显著改变了黄泥土壤古菌群落结构。进一步对不同量秸秆施用下土壤古菌群落结构的分析发现,秸秆施用量为5%时高砂土壤古菌群落显著不同于秸秆施用量为1%和2%的土壤,而1%和2%秸秆施用量之间并无显著差异;而对黄泥土,仅秸秆施用量为1%和2%时古菌群落存在着显著差异。为了进一步探究土壤古菌群落迁移的驱动因子,冗余分析(RDA)发现,pH和C/N比是秸秆还田下两种类型土壤古菌群落迁移的重要影响因子。综合分析认为,秸秆还田主要通过改变土壤性质来调控古菌群落结构,而不同类型土壤的古菌群落结构对秸秆还田的响应亦不同。

长期不同施肥黑土细菌和古菌群落结构及主效影响因子分析

【目的】依据黑龙江省农科院34年的长期定位试验,探讨影响东北黑土细菌和古菌区系的主效环境因子。【方法】试验采集不施肥（CK）、施氮磷肥（NP）、施氮钾肥（NK）、施磷钾肥（PK）、施氮磷钾肥（NPK）5个施肥处理的耕层土样借助传统化学分析方法和Illumina Miseq高通量测序技术解析土壤化学性状和细菌与古菌的群落结构特征,并对细菌和古菌群落结构与环境因子进行相关性分析。【结果】1）不同施肥处理土壤细菌和古菌群落结构存在显著差异与CK相比,4种施肥处理均降低了古菌丰富度,NPK处理增加了土壤细菌的丰富度、多样性以及古菌的多样性;变形菌门（Proteobacteria）、酸杆菌门（Acidobacteria）是所有土样中的优势菌群,占细菌与古菌总量的38.2%-42.9%。施肥条件下,放线菌门（Actinobacteria）、浮霉菌门（Planctomycetes）、绿弯菌门（Chloroflexi）、蓝藻门（Cyanobacteria）的相对丰度降低芽单胞菌门（Gemmatimonadetes）、厚壁菌门（Firmicutes）的相对丰度升高而其他菌门的相对丰度对不同施肥处理的响应不同。2）施用氮肥显著改变了土壤化学性状,长期施氮（尿素）处理的土壤全氮、速效氮和有机质含量显著高于不施氮处理而pH则显著降低。3）RDA分析结果显示,pH对土壤细菌和古菌群落结构的影响最大解释了66.5%的变化;其他环境因子则共解释了细菌与古菌群落33.5%的变化各因子的贡献率依次为pH〉速效钾〉有效磷〉有机质。Pearson相关性分析结果也表明,细菌和古菌群落与土壤化学指标间存在密切的相关关系。【结论】解析了长期不同施肥条件下土壤细菌和古菌的群落结构特征,确定了pH是影响土壤细菌和古菌区系的主效环境因子,氮磷钾均衡施肥不仅显著提高了作物产量和丰富了土壤养分含量,同时也增加了土壤细菌的丰富度、多样性以及古菌的多样性,有利于维持良好的土壤生态环境。研究结果对揭示东北黑土肥力演变机制、建立合理的施肥制度具有重要的理论价值。

湖泊氮素氧化及脱氮过程研究进展

自然界中氮的生物地球化学循环主要由微生物驱动,由固氮作用、硝化作用、反硝化作用和氨化作用来完成。过去数十年间,随着异养硝化、厌氧氨氧化和古菌氨氧化作用的发现,人们对环境中氮素循环认识逐步深入,提出了多种脱氮途径新假说。对湖泊生态系统中氮素的输入、输出及其在水体、沉积物和水土界面的迁移转化过程进行了概括,对湖泊生态系统中反硝化和厌氧氨氧化脱氮机理及脱氮效率的最新研究进展进行了探讨,并对以后的氮素循环研究进行了展望。

古菌生物标志物古海水温度指标TEX_(86)研究进展

TEX86是最近几年提出的一个古海水温度重建指标,它是基于由古菌的一个分支Marine Crenarchaeota所产生的一组生物标志物(GDGTs)的比值。培养实验、水体颗粒物及大洋表层沉积物的研究结果都显示,温度是TEX86指标的主要影响因素,而盐度、营养盐等其他环境因子对TEX86指标无明显影响。由于陆源物质中也含有少量GDGTs,TEX86重建近海温度记录会有较大的误差。但是TEX86和另一个生物标志物指标BIT的同时测定也使TEX86用于近海古温度重建。与通常用的U3K7′古海水温度指标相比,TEX86指标可以应用于高于29℃的高温海域,目前已被成功地应用于地质历史中高温期古海水温度的重建。TEX86指标将为重建西太平洋古温度记录提供一种有效的方法。