毒死蜱乳油对辣椒根围土壤细菌群落结构的影响

【目的】了解有机磷杀虫剂毒死蜱对土壤细菌群落结构的作用。【方法】联合微生物平板计数法、末端限制性片段多态性分析,选择PRIMER 5进行群落结构分析,以研究不同浓度的毒死蜱对辣椒根围可培养和不可培养细菌群落结构的影响。【结果】毒死蜱施入后前30 d,3个处理组的可培养细菌较对照组具有显著差异(P0.05),但在第30天后,处理组可培养细菌数均能恢复到对照水平。采用PRIMER 5对T-RFLP数据进行多角度分析发现,HaeⅢ酶切片段中,对照组C3、处理组Y0和Z2的细菌群落结构较整体聚类较远。HhaⅠ酶切片段中,150μg/g的毒死蜱处理组(Z0)在第0天表现出最大的群落差异。ANOSIM表明,以不同浓度的毒死蜱分组,各组间细菌群落组成差异不显著(HaeⅢ:Global R=0.041,P=0.168;HhaⅠ:Global R=-0.04,P=0.842);以不同取样时间分组时,细菌群落组成差异显著(HaeⅢ:Global R=0.304,P=0.001;HhaⅠ:Global R=0.28,P=0.001)。经SIMPER分析所有TRFs可知,对群落丰度贡献最大的片段分别为TRF239、TRF240、TRF241。在线比对得到其代表菌群有芽孢杆菌属(Bacillus sp.)、梭菌属(Clostridium sp.)、葡萄球菌属(Staphylococcus sp.)、八叠球菌属(Sarcina sp.)、假单胞菌属(Pseudomonas sp.)等。【结论】高浓度的毒死蜱会对土壤细菌群落产生影响,抑制根围细菌生长,从而遏制植物的健康生长,因而有必要及时采取措施以减少大量重复使用毒死蜱所带来的危害。     

环洞庭湖四个淡水湖渔场底泥产几丁质酶细菌的筛选鉴定、分布和产酶量研究

为了解淡水湖渔场底泥中产几丁质酶菌株的产酶量和分布情况，对环洞庭湖的4个淡水湖渔场的表层底泥样品进行了无菌采集。利用稀释涂布平板法、点种法和摇瓶发酵法从底泥样品中筛选分离到26株产几丁质酶菌株，几丁质酶活在0.07～0.69 U/mL之间。对26株产几丁质酶菌株进行16S rRNA基因鉴定和系统发育分析。结果表明，26株菌株都分布于变形菌门(Proteobacteria)和厚壁菌门(Firmicutes)的芽胞杆菌属(Bacillus)、假单胞菌属(Pseudomonas)、不动杆菌属(Acinetobacter)和微小杆菌属(Exiguobacterium)。且产几丁质酶细菌在4个淡水湖渔场表层底泥中的分布情况为安乐湖>东湖>北民湖>西湖。对产几丁质酶菌株的降解活力、种类组成及数量分布的研究可为淡水湖渔场底泥中产几丁质酶微生物资源的开发及应用提供参考。     

一株产漆酶细菌的分离鉴定及酶学性质研究

[目的]分离获得产漆酶的细菌菌株,研究漆酶的酶学性质并应用于染料脱色.[方法]利用含铜的富集培养基筛选产漆酶细菌;通过形态特征、生理生化试验及16SrDNA序列分析等方法进行鉴定;以丁香醛连氮为底物测定漆酶的酶学性质;通过测定染料在最大吸收波长下吸光值的变化评价漆酶对染料的脱色效果.[结果]从森林土壤中筛选到一株漆酶高产菌株LS05,初步鉴定为解淀粉芽孢杆菌(Bacillus amyloliquefaciens);菌株LS05的芽孢漆酶以丁香醛连氮为底物的最适pH为6.6,最适温度为70℃;该酶具有较好的稳定性,经70℃处理10h或在pH 9.0条件下放置10d后可保留活性.对抑制剂SDS和EDTA具有一定的抗性,在碱性条件下可有效脱色不同的工业染料,RB亮蓝、活性黑和靛红1h内的脱色率达93％以上.[结论]Bacillus amyloliquefaciens LS05的芽孢漆酶在高温和碱性条件下稳定性强,相对于真菌漆酶具有更好的工业应用特性,可有效用于工业染料废水的处理.     

亚洲韧皮杆菌兼性厌氧型伴生细菌鉴定及优势菌群分析

以定向分离培养和基于16S rDNA的PCR-DGGE (Denaturing gradient gel electrophoresis, DGGE)方法, 分析感黄龙病柑橘与健康柑橘植株不同部位的内生细菌多样性, 分离柑橘组织共获得19株可培养的兼性厌氧型内生细菌, 经形态、生理生化结合16S rDNA分子方法鉴定其隶属于12个属, 其中短小杆菌属Curtobacterium sp. (IF: 29.07%)、芽孢杆菌属Bacillus sp. (IF: 23.12%)和微杆菌属Microbacterium sp. (IF: 21.09%)为罹病植株的优势菌群, 芽孢杆菌属Bacillus sp. (IF: 21.03%)、动性球菌属Planococcus sp. (IF: 20.69%)和假单胞菌属Pseudomonas sp. (IF: 17.44%)为无症健株的优势菌群。对DGGE方法得到的50条16S rDNA目标条带进行序列比对, 共鉴定出9个属的细菌, 结果表明沙雷氏菌属Serrations sp. (IF: 28%)是优势菌属, 泛菌属Pantoea sp. (IF: 14%)是次优势菌属; 病果桔络中黄龙病菌含量最高(>1%), 而罹病植株其他部位的黄龙病菌丰度较低。PCR-DGGE 图谱也显示感病和健康柑橘组织的内生细菌存在差异。     

玉溪地区自然陈化烟叶表面可培养细菌多样性研究

目的为了较全面的了解陈化烟叶的细菌多样性,进一步挖掘其中的有益微生物。方法以种植于玉溪元江县的红大烤烟品种为材料,利用16SrDNA克隆测序技术,系统研究了云南玉溪红塔区和元江县两仓库中不同自然陈化时期烟叶表面可培养微生物的种群结构。结果陈化初期,烟叶表面细菌数量较少,元江县低水分烟叶陈化30d时细菌数量达到高峰;红塔区高水分烟叶陈化4.5个月时细菌数量达最大;经过16SrDNA鉴定,烤烟叶面细菌包括芽孢杆菌属(Bacillus sp.)、肠杆菌属(Enterobacter sp.)、类芽孢杆菌属(Paenibacillus sp.)和泛菌属(Pantoeasp.)等8个细菌属。结论不同时期、不同地点陈化烟叶表面细菌的优势种群不尽相同,而芽孢杆菌属始终为优势种群。另外,研究中分离到的大量可培养细菌,为进一步筛选烟叶表面有益细菌提供了重要线索。     

高寒森林溪流微生物群落结构的季节性变化

高寒森林溪流不仅是区域河流的源头,而且是联系陆地与水域的生态纽带。微生物活动可能成为控制溪流生态系统过程的关键因子,但其结构与动态过程缺乏必要关注。因此,结合同步温度动态监测,采用实时荧光定量PCR和DGGE技术,在2014年到2015年冻融季节和生长季节关键时期对比研究了川西高寒森林溪流和森林林下土壤中微生物群落的动态特征。研究结果发现,高寒森林溪流具有较低的真菌和细菌群落丰度;与森林土壤相同,溪流在冻融季节表现出相对生长季节更高的真菌/细菌比,而且从冻融季节到生长季节,溪流微生物丰度动态也表现出明显的季节性变化特征。与森林土壤不同的是,溪流中细菌和真菌的丰度及其Shannon-Wiener多样性指数的最高值均出现在生长季节而不是冬季冻融季节,并且溪流中细菌丰度在季节性变化的不同时期具有显著差异(P0.05)。此外,森林土壤细菌类群以芽孢杆菌属(Bacillus sp.)比例相对较高,真菌类群则以格孢菌属(Pleosporales sp.)、曲霉属(Aspergillus sp.)和其他一些子囊菌门(Ascomycota)的类群为优势;而溪流细菌类群以红球菌属(Rhodococcus sp.)为主,真菌类群则以曲霉属和空团菌属(Cenococcum sp.)为主。同时,季节性变化中温度、p H、水溶性有机碳和溶解氧等环境因子可显著影响溪流微生物群落结构及其组成,这些环境因子在高寒森林溪流微生物群落的季节性变化过程中具有重要的作用。     

氟化物对家蚕耐氟和氟敏感品种肠道中留存产酶菌群落组成和多样性的影响

【目的】研究氟化物对家蚕Bombyx mori肠道内留存产酶菌的影响, 有助于了解家蚕耐氟和氟敏品种的耐氟力差异。【方法】分别给家蚕耐氟品种T6和氟敏品种734添食NaF溶液浸泡后的新鲜桑叶, 至5龄第3天取材。采用筛选培养基筛选产蛋白酶、 纤维素酶、 脂肪酶、 淀粉酶的菌株, 并结合16S rDNA系统发育关系, 对菌株进行分类鉴定。【结果】家蚕肠道内产消化酶细菌有芽孢杆菌属Bacillus、 葡萄球菌属Staphylococcus、 肠杆菌属Enterobacter和不动杆菌属Acinetobacter和微小杆菌属Exiguobaterium, 其中芽孢杆菌Bacillus sp.、 葡萄球菌Staphylococcus sp. 和不动杆菌Acinetobacter sp.细菌可同时产4种酶。氟中毒后T6肠道内产酶菌由5种减少到4种, 734肠道内产酶菌由2种减少到1种。【结论】家蚕肠道内留存的产酶菌与家蚕自身的耐氟能力相关。     

甘草内生细菌的分离及拮抗菌株鉴定

从乌拉尔甘草健康植株的根茎叶中共分离到内生细菌98株,经初步鉴定芽孢杆菌属(Bacillus sp.)为优势种群,约占30%;从不同生长年份甘草的根、茎、叶组织中分离内生细菌种群密度从5.0×104cfu/g~2.9×107cfu/g鲜重不等。采用平板对峙方法筛选出6株对植物病原菌有明显体外拮抗活性的菌株,通过菌落、菌体形态观察、生理生化反应及16S rDNA序列分析,同时结合Biolog细菌自动鉴定系统验证,鉴定这6株拮抗菌分属萎缩芽孢杆菌(Bacillus atrophaeus)、多粘类芽孢杆菌(Paenibacillus polymyxa)、枯草芽孢杆菌(Bacillus subtilis)、Paenibacillus ehimensis。     

环状糊精葡糖基转移酶产生菌——碱杆菌的分类研究

自土壤中分离到两类能在碱性培养基中生长并产生环状糊精葡糖基转移酶的细菌。经鉴定,一类属芽孢杆菌,另一类为无芽孢的杆状细菌《伯杰氏鉴定细菌学手册》(第八版)和现有其他分类文献均未见其分类位置,拟订为新属碱杆菌属(Alcalibacterium gen. Nov.)和新种产环糊精碱杆菌(Alcalibacterium cyclodextrtmogenes sp. Nov.)。     

柑橘黄龙病寄主长春花内生细菌的分离及功能鉴定

【目的】感柑橘黄龙病长春花植株与健康长春花植株不同部位内生细菌菌群结构及功能对柑橘黄龙病菌与长春花内生细菌的相关性研究提供理论基础。【方法】利用兼性厌氧可培养技术以及植物内生菌功能特性分析相结合的方法。【结果】分别从感病和健康长春花叶、茎、根的组织中分离获得67株内生细菌,与GenBank中29种细菌的相似性达到97%-100%。其中短小杆菌属(Curtobacterium sp.)、欧文氏菌属(Erwinia sp.)、蜡样芽胞杆菌(Bacillus cereus)为感病长春花内生细菌的优势菌群,鞘胺醇单胞菌属(Brevundimonas sp.)、芽胞杆菌属(Bacillus sp.)为健康长春花内生细菌的优势菌群;马胃葡萄球菌(Staphylococcus equorum)为两者的共同优势菌群。29种内生细菌进行功能分析,其中6株内生细菌至少具有4种功能特性,分属于马胃葡萄球菌、苏云金芽孢杆菌、巨大芽孢杆菌、短小杆菌属、摩氏摩根菌(Morganella morganii)及溶杆菌属(Lysobacter sp.)5个属。【结论】感病与健康长春花植株中均含有丰富的内生细菌且差异较大,黄龙病菌的存在改变了长春花原有内生细菌的菌群结构。通过分析菌群的差异,有望找到与柑橘黄龙病菌生长相关的菌种。     

中国东北样带树种(属)的空间特性及变化

The 16 tree species on Northeast China Transect (NECT) were analyzed from the change of geographical distribution, frequency and dominance pattern and the spatial correlation at landscape scale in 1986 and 1994. Pinus koraiensis Sieb. et Zucc. and Fraxinus rhynchophylla Hemsl. had spread rapidly towards west and east, respectively. The frontier form of species had close relation with its movement. The patch size of Pinus koraiensis, Populus davidiana Dode., Phellodendron amurense Rupr., Juglans mandshurica Maxim., Fraxinus mandshurica Rupr., Betula dahurica Pall., Picea koraiensis Nakai, Abies nephrolepis Maxim. and Larix olgeusis var. koreana Nakai decreased, however, Quercus mongolica Fisch., Betula costata Trautv., Acer mono Maxim., Tilia spp., Ulmus spp., Betula platyphylla Suk. and Fraxinus rhynchophylla increased. The frequency pattern of Populus davidiana, Betula platyphylla, Fraxinus rhynchophylla and Betula dahurica changed significantly. The dominance pattern of Populus davidiana, Tilia spp., Juglans mandshurica, Betula platyphylla, Betula dahurica and Abies nephrolepis changed significantly. The spatial correlation between Quercus mongolica and Betula dahurica, Betula costata and Picea spp., Betula costata and Abies nephrolepis, Picea spp. and Abies nephrolepis declined, however, the spatial correlation between Larix spp. and Betula platyphylla, Acer mono and Ulmus spp. increased.     

Characterization of a laccase-like multicopper oxidase from newly isolated Streptomyces sp. C1 in agricultural waste compost and enzymatic decolorization of azo dyes

Laccases or laccase-like multicopper oxidases (LMCOs) could catalyze the oxidation of various substrates coupled to the reduction of oxygen to water. In this study, eight strains with laccase activity were isolated from composting samples in different phases, among which strain C1 isolated from the thermophilic-phase sample presented the highest laccase activity. The purified LMCO of strain C1 showed a single protein band on SDS-PAGE gel with a molecular mass of about 38 kDa. The novel laccase showed alkaline resistance and moderate thermostability. The enzyme activity was activated by some metal ions such as Cu²⁺, Co²⁺ and Fe³⁺ at the concentration of 1 mM, while was strongly inhibited in the presence of Hg²⁺. The LMCO could efficiently decolorize the indigo carmine and diamond black PV with syringaldehyde as mediator, which suggested a great potential for dye decolorization in the textile industry. The novel strain was identified as Streptomyces sp. C1. The finding of new laccase-producing Streptomyces sp. C1 in this study will also contribute to the further explanation of the function of Actinomycetes in the thermophilic phase of composting.     

Gene structure and molecular analysis of the laccase-like multicopper oxidase (LMCO) gene family in <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis>

Completed genome sequences have made it clear that multicopper oxidases related to laccase are widely distributed as multigene families in higher plants. Laccase-like multicopper oxidase (LMCO) sequences culled from GenBank and the Arabidopsis thaliana genome, as well as those from several newly cloned genes, were used to construct a gene phylogeny that clearly divided plant LMCOs into six distinct classes, at least three of which predate the evolutionary divergence of angiosperms and gymnosperms. Alignments of the predicted amino acid sequences highlighted regions of variable sequence flanked by the highly conserved copper-binding domains that characterize members of this enzyme family. All of the predicted proteins contained apparent signal sequences. The expression of 13 of the 17 LMCO genes in A. thaliana was assessed in different tissues at various stages of development using RT-PCR. A diversity of expression patterns was demonstrated with some genes being expressed in a constitutive fashion, while others were only expressed in specific tissues at a particular stage of development. Only a few of the LMCO genes were expressed in a pattern that could be considered consistent with a major role for these enzymes in lignin deposition. These results are discussed in the context of other potential physiological functions for plant LMCOs, such as iron metabolism and wound healing.     

土壤湿度对东北3种主要树种凋落物分解的影响

结合丰林国家自然保护区原始阔叶红松林1998-2017年表层(0～10 cm)土壤湿度监测数据,评估了全球变化背景下土壤湿度变化对东北主要森林树种红松、臭冷杉和白桦凋落物分解的影响.结果表明: 在同一土壤湿度水平下,凋落物分解速率随着凋落物质量的增加而增大,即表现为白桦>臭冷杉>红松.凋落物的分解速率随着土壤湿度的降低而减小.白桦、臭冷杉和红松3种凋落物的土壤湿度敏感性指数(M₁₀)分别为0.782、0.789和0.827,土壤湿度水平每降低10%,初始分解速率分别减小21.8%、21.1%和17.3%.高质量凋落物(高氮含量、低碳氮比、低木质素含量)的分解速率对土壤湿度变化的响应更敏感.凋落物分解速率在不同凋落物类型间的差异随着土壤湿度的降低而缩小.近20年间,原始阔叶红松林土壤湿度呈显著减少趋势,对凋落物分解表现为抑制作用.在全球变化背景下,随着气温的升高,土壤湿度将继续降低,对凋落物的抑制作用会进一步增强,并将部分抵消因温度升高所带来的凋落物分解速率增大的压力.     

子午岭林区白桦-辽东栎混交林光合生理生态特征研究

对黄土高原子午岭次生林区白桦林、辽东栎林和白桦-辽东栎混交林3种林分的土壤物理特性和叶片光合特性进行了研究。结果表明:(1)白桦-辽东栎混交林地的土壤水分明显改善,其土壤容重最小、土壤孔隙度最大,且均优于纯林,即混交林地有深层次的土壤水分可供利用,并改善了土壤的物理结构;(2)辽东栎林的光合速率和气孔导度最大,其次为白桦-辽东栎混交林,水分利用率(WUE)为混交林白桦>混交林辽东栎>辽东栎林>白桦林;(3)混交林中白桦、辽东栎的Fv/Fm和Fv/Fo值均较大,与纯林差异不显著;白桦林和辽东栎林的qP和NPQ值均大于混交林。     

Bio-prospecting Bacterial Diversity of Hot Springs in Northern Himalayan Region of India for Laccases

Bacterial diversity of hot springs of northern Himalayan region of India was studied and explored for laccases, the multicopper enzymes applicable in a large number of industries due to their ability to utilize a wide range of substrates. 220 operational taxonomic units (OTUs) out of 5551 sequence reads for bacterial diversity and 3 OTUs out of 19 sequence reads for Laccase like multicopper oxidases (LMCOs) diversity were generated. Bacteroidetes (74.28%) was the most abundant phylum including genus Paludibacter (66.96%), followed by phylum Proteobacteria (24.53%) including genera Chitinilyticum (7.55%) and Cellvibrio (6.14%). In case of laccase diversity, three LMCO sequences showed affiliation with proteobacteria and one with two domain laccase from uncultivable bacteroidetes. LMCO sequences belonged to H and N families.     

An evidence of laccases in archaea

Laccases (benzenediol:oxygen oxidoreductase, EC 1.10.3.2) are a diverse group of multicopper oxidases that catalyze the oxidation of a variety of aromatic compounds. Here we present evidence for distribution of laccases among archaea and their probable functions. Putative laccase genes have been found in different archaeal groups that might have branched off early during evolution, e.g. Haloarcula marismortui ATCC 43049, Natronomonas pharaonis DSM2160, Pyrobaculum aerophilum IM2, Candidatus Nitrosopumilus maritimus SCM1, Halorubrum lacusprofundi ATCC 49239. Most of the archaeal multicopper oxidases reported here are of Type 1 and Type 2 whereas type 3 copper-binding domain could be found in Pyrobaculum aerophilum IM2 and Halorubrum lacusprofundi ATCC49239. An analysis of the genome sequence database revealed the presence of novel types of two-domain laccases in archaea. ed using this method. CyMVin the positive samples of Phalaenopsis sp. and Arachnis sp. was confirmed by DNA sequencing and cp gene homeology blast. The results showed that CyMV extracted from the leaves of orchid in Hangzhou, Zhejiang Province, China, could be derived from Kunming city (KM), Yunnan Province, China. This method characterized by high sensitivity, specificity, and precision is suitable for early diagnosis and quantitative detection of CyMV.     

A crystallographic and spectroscopic study on the effect of X-ray radiation on the crystal structure of Melanocarpus albomyces laccase

Laccases (p-diphenol dioxygen oxidoreductases) belong to the family of blue multicopper oxidases, which catalyse the four-electron reduction of dioxygen to water concomitantly through the oxidation of substrate molecules. Blue multicopper oxidases have four coppers, a copper (T1) forming a mononuclear site and a cluster of three coppers (T2, T3, and T3') forming a trinuclear site. Because X-rays are known to liberate electrons during data collection and may thus affect the oxidation state of metals, we have investigated the effect of X-ray radiation upon the crystal structure of a recombinant laccase from Melanocarpus albomyces through the use of crystallography and crystal absorption spectroscopy. Two data sets with different strategies, a low and a high-dose data set, were collected at synchrotron. We have observed earlier that the trinuclear site had an elongated electron density amidst coppers, suggesting dioxygen binding. The low-dose synchrotron structure showed similar elongated electron density, but the high-dose X-ray radiation removed the bulk of this density. Therefore, X-ray radiation could alter the active site of laccase from M. albomyces. Absorption spectra of the crystals (320, 420, and 590nm) during X-ray radiation were measured at a home laboratory. Spectra clearly showed how that the band at 590nm had vanished, resulting from the T1 copper being reduced, during the long X-ray measurements. The crystal colour changed from blue to colourless. Absorptions at 320 and 420nm seemed to be rather permanent. The absorption at 320nm is due to the T3 coppers and it is proposed that absorption at 420nm is due to the T2 copper when dioxygen or a reaction intermediate is close to this copper.     

Decomposition of different root branch orders and its dominant controlling factors in four temperate tree species北大核心CSCD

Aims Fine root decomposition is the major pathway of carbon and nutrient input to the soil in forest ecosystems. However, the patterns and controlling factors of the decomposition of these roots, especially the finest roots, are poorly understood. Methods Using a root branch-order classification, we separated the first four orders of fine root systems of Pinus koraiensis, Larix gmelinii, Fraxinus mandschurica and Betula platyphylla into two classes: first- and second-order roots combined into lower-order; third- and fourth-order roots combined into higher-order. We conducted a four-year field litterbag study on decomposition of these four root orders of four temperate tree species in northeast China. Important findings The results showed that the lower-order and higher-order roots had a decomposition rate constant of 0.342 and 0.461 for Pinus koraiensis, 0.304 and 0.436 for Larix gmelinii, 0.450 and 0.555 for Fraxinus mandschurica, and 0.441 and 0.579 for Betula platyphylla, respectively. We observed slower decay rates in lower-order than in higher-order roots in all four studied tree species. The root decay constants (k) was significantly correlated with both acid-unhydrolyzable fraction (AUF) and total non-structural carbohydrate (TNC). We concluded that slow decomposition of lower-order roots was mainly driven by their high AUF and low TNC concentrations. © Chinese Journal of Plant Ecology.