三倍体毛白杨不同组织内生细菌多样性分析

【背景】三倍体毛白杨非常适合黄河区域生态经济发展,是我国林业推广项目的重要树种。内生细菌在三倍体毛白杨不同组织中广泛存在,对三倍体毛白杨具有防病、促生、固氮和生物修复等生物学作用。【目的】通过分析三倍体毛白杨不同组织内生细菌多样性,可以充分挖掘其蕴含的丰富微生物资源。【方法】以北京林业大学山东冠县毛白杨基地的三倍体毛白杨为材料,应用16S rRNA基因高通量测序技术对其根、茎、叶中内生细菌多样性进行了分析,阐述三倍体毛白杨不同组织内生细菌多样性的变化趋势和规律,为其内生细菌的进一步应用奠定理论基础。【结果】三倍体毛白杨根部内生细菌群落丰富度及多样性最高,叶片中最低。高通量测序结果显示,在全部样本中,假单胞菌门和放线菌门为优势门,伯克氏菌属(Burkholderia)、假诺卡氏菌属(Pseudonocardia)和食酸菌属(Acidovorax)为优势属,不同组织的内生细菌群落结构组成差异显著;16S rRNA基因功能预测结果显示,三倍体毛白杨内生细菌的功能主要涉及氨基酸代谢、维生素代谢、芳香族化合物降解和糖酵解等。通过分离培养共获得217株内生细菌,分属于23个属44个种,其中有4株1...     

镉对超积累和非超积累生态型东南景天内生细菌多样性的影响

重金属胁迫对植物内生细菌群落结构的影响在很大程度上是未知的,目前也很少有研究超积累植物内生细菌的群落结构与多样性对根际土壤中重金属的响应。【目的】探索在不同镉污染水平下,超积累(HE)和非超积累生态型(NHE)东南景天的根系、茎和叶片中内生细菌的群落结构与多样性的变化及其差异性,试图从植物-内生菌之间的相互关系的角度补充解释2种生态型东南景天对有效态镉忍耐和积累能力的差异。【方法】采用Illumina新一代测序方法分析了在不同Cd~(2+)浓度土壤上生长的2种生态型东南景天根、茎和叶中的内生细菌群落结构。【结果】高浓度Cd~(2+)抑制NHE东南景天的生长,内生细菌的丰富度和多样性也降低;然而,高浓度Cd~(2+)促进HE东南景天的生长,茎和根系内生细菌的丰富度增加。在3种土壤上,2种生态型东南景天叶片、茎和根系内生细菌均以变形菌门(Proteobacteria)、厚壁菌门(Firmicutes)、拟杆菌门(Bacteroidetes)和放线菌门(Actinobacteria)占优势。随着土壤中Cd~(2+)浓度的增加,HE东南景天叶片中Gammaproteobacteria纲、Negativicutes纲和Clostridia纲的相对丰度显著增加,茎中Alphaproteobacteria纲的相对丰度显著增加,Clostridia纲的相对丰度显著减少;NHE东南景天叶片中Alphaproteobacteria纲、Gammaproteobacteria纲和Clostridia纲的相对丰度没有显著变化,茎中Negativicutes纲的相对丰度显著减少,根系中Betaproteobacteria纲和Clostridia纲的相对丰度显著减少,Negativicutes纲却显著增加。在高Cd~(2+)污染土壤(50mg/kg)上,HE东南景天叶片中Sphingomonas属和茎中Veillonella属的相对丰度均大于NHE,且HE东南景天根系内生细菌的第一、第二、第三优势菌Veillonella、Sphingomonas、Prevotella属细菌均没有出现在NHE东南景天根系。【结论】土壤Cd~(2+)污染水平对2种生态型东南景天叶、茎、根中的内生菌群落结构有显著影响。     

Effect of inoculation method and plant growth medium on endophytic colonization of sorghum by the entomopathogenic fungus <Emphasis Type="Italic">Beauveria bassiana</Emphasis>

A study was conducted to determine the effect of inoculation method and plant growth medium on colonization of sorghum by an endophytic Beauveria bassiana. Colonization of leaves, stems, and roots by B. bassiana was assessed 20-days after application of the fungus. Although B. bassiana established as an endophyte in sorghum leaves, stems, and roots regardless of inoculation method (leaf, seed, or soil inoculation), plant growth medium (sterile soil, non-sterile soil, or vermiculite) apparently influenced colonization rates. Seed inoculation with conidia caused no stem or leaf colonization by the fungus in non-sterile soil but did result in substantial endophytic colonization in vermiculite and sterile soil. Leaf inoculation did not result in root colonization, regardless of plant growth medium. Endophytic colonization was greater in leaves and stems than roots. Endophytic colonization by B. bassiana had no adverse effects on the growth of sorghum plants. Leaf inoculation with a conidial suspension proved to be the best method to introduce B. bassiana into sorghum leaves for plants growing in either sterile or non-sterile soil. Further research should focus on the virulence of endophytic B. bassiana against sorghum stem borers.     

Ecology of bacterial endophytes associated with wetland plants growing in textile effluent for pollutant-degradation and plant growth-promotion potentials

In this study, 41 culturable endophytic bacteria were isolated from the roots and shoots of three wetland plants, Typha domingensis, Pistia stratiotes and Eichhornia crassipes, and identified by 16S rRNA gene sequencing. Textile effluent-degrading and plant growth-promoting activities of these endophytes were determined. The analysis of endophytic bacterial communities indicated that plant species had a pronounced effect on endophytic bacterial association and maximum endophytes (56.5%) were associated with T. domingensis. These endophytic bacteria mainly belonged to different species of the genera Bacillus (39%), Microbacterium (12%) and Halomonas (12%). Eight of the 41 strains showing maximum efficiency of textile effluent degradation also exhibited plant growth-promoting activities such as production of indole-3-acetic acid and siderophore, presence of 1-amino-cyclopropane-1-carboxylic acid deaminase, and solubilization of inorganic phosphorous. This is the first study describing the diversity and plant-beneficial characteristics of the textile effluent-degrading endophytic bacteria associated with wetland plants. T. domingensis showed better growth in textile effluent and also hosted maximum number of endophytic bacteria in roots and shoots. The interactions between T. domingensis and its associated endophytic bacteria could be exploited to enhance the efficiency of constructed wetlands during the remediation of industrial effluent.     

药用植物青蒿不同种类的内生菌抑菌活性分析

为了研究青蒿不同种类的内生菌抑制细菌和抑制真菌的活性,该研究采用组织块法和研磨法从青蒿的根、茎、叶中分离内生细菌、放线菌和真菌,以大肠埃希菌(Escherichia coli)(CICC 23657)、枯草芽孢杆菌(Bacillus subtilis)(CICC 10275)、金黄色葡萄球菌(Staphylococcus aureus)(CICC 10384)、黑曲霉(Aspergillus niger)(CICC 2487)、酿酒酵母(Saccharomyces cerevisiae)(CICC 33032)为指示菌,采用琼脂块法和双层平板法检测内生菌的抑菌活性。结果表明:(1)从青蒿植株中共分离到76株内生菌,其中内生细菌19株、内生放线菌34株、内生真菌23株。从分离部位来看,56株来自于茎段、17株来自于根段、3株来自叶片。(2)内生细菌中抑菌活性菌株占总菌株的比例最高,为95%,内生放线菌和内生真菌中抑菌活性菌株的比例分别为41%、35%。(3)内生细菌的抗菌谱较广;虽然内生放线菌的抗菌谱较窄,但其中高抗菌株较多,尤其对酿酒酵母的抑菌效果好。综上结果显示,药用植物青蒿中存在着丰富的有抑菌活性的内生菌,且不同种类的内生菌抑菌活性不同。     

Diversity of Cultivated Endophytic Bacteria from Sugarcane: Genetic and Biochemical Characterization of Burkholderia cepacia Complex Isolates

Bacteria were isolated from the rhizosphere and from inside the roots and stems of sugarcane plants grown in the field in Brazil. Endophytic bacteria were found in both the roots and the stems of sugarcane plants, with a significantly higher density in the roots. Many of the cultivated endophytic bacteria were shown to produce the plant growth hormone indoleacetic acid, and this trait was more frequently found among bacteria from the stem. 16S rRNA gene sequence analysis revealed that the selected isolates of the endophytic bacterial community of sugarcane belong to the genera of Burkholderia, Pantoea, Pseudomonas, and Microbacterium. Bacterial isolates belonging to the genus Burkholderia were the most predominant among the endophytic bacteria. Many of the Burkholderia isolates produced the antifungal metabolite pyrrolnitrin, and all were able to grow at 37°C. Phylogenetic analyses of the 16S rRNA gene and recA gene sequences indicated that the endophytic Burkholderia isolates from sugarcane are closely related to clinical isolates of the Burkholderia cepacia complex and clustered with B. cenocepacia (gv. III) isolates from cystic fibrosis patients. These results suggest that isolates of the B. cepacia complex are an integral part of the endophytic bacterial community of sugarcane in Brazil and reinforce the hypothesis that plant-associated environments may act as a niche for putative opportunistic human pathogenic bacteria.     

毛泡桐内生真菌的分离、拮抗细菌菌株的筛选和鉴定

为寻找新的能产生抗生素的植物内生真菌,采用3种培养基对毛泡桐进行内生真菌的分离,以大肠埃希菌、枯草芽胞杆菌、金黄色葡萄球菌、青枯假单胞菌为指示菌,利用琼脂块法和滤纸片扩散法筛选能抑制细菌的菌株;通过形态特征和ITS序列分析鉴定高活性菌株。结果从毛泡桐的根、茎、叶中共分离得到46株内生真菌,至少能抑制一种指示菌的有9株,其中菌株KLBMP-Pt630、KLBMP-Pt675和KLBMP-Pt686活性较强,鉴定结果显示:KLBMP-Pt630为三线镰刀菌、KLBMP-Pt675为棒曲霉、KLBMP-Pt686属于肉座菌目真菌。     

巨菌草不同生长时期的内生固氮菌群组成分析

【背景】禾本科植物中存在着丰富的内生固氮菌资源,可为植物的生长、营养利用、增强抗逆性等起到重要的促进作用。【目的】揭示巨菌草不同生长时期根、茎、叶内生固氮细菌的组成及其变化。【方法】采用高通量测序技术对不同生长时期的巨菌草根、茎、叶内生固氮菌群进行群落分析。【结果】不同生长时期巨菌草根、茎、叶的15个样本分别得到4-6万条有效序列,主要分布在360 bp左右。根部巨菌草内生固氮菌群在成熟期最高,茎部和叶部均为拔节期最高,同一生长时期则为根叶茎,变化趋势与巨菌草植物样本的固氮酶活性变化趋势一致,其主要的菌群门类为变形菌门(Proteobacteria)和蓝藻菌门(Cyanobacteria),主要核心属为克雷伯氏菌属(Klebsiella)、草螺菌属(Herbaspirillum)和慢生根瘤菌(Bradyrhizobium)。整体上看,根、叶部来源的各自微生物菌群组成较为接近,茎部来源的菌群与根部、叶部有交叉,成熟期根部的联合固氮菌群种类和丰度最高。典范对应分析表明各来源样本固氮菌群的组成主要受环境温度影响,其次为湿度和pH。【结论】不同生长时期巨菌草根、茎、叶固氮菌群的组成及丰度存在着较大的差异,本研究可为巨菌草内生固氮菌群资源的开发和利用以及种质资源库的建立提供基础依据。     

Isolation and characterization endophytic bacteria from hyperaccumulator Sedum alfredii Hance and their potential to promote phytoextraction of zinc polluted soil

The aim of this study was to isolate and characterize endophytic bacteria from roots, stems and leaves of Zn/Cd hyperaccumulator Sedum alfredii. Endophytic bacteria were observed in roots, stems and leave of S. alfredii, with a significantly higher density in roots, followed by leave and stems. A total of fourteen bacterial endophytes were isolated and are closely related phylogenetically to Pseudomonas, Bacillus, Stenotrophomonas, Acinetobacte by 16S rRNA sequence analysis. Most of the endophytic bacteria were found to exhibit high Zn and Cd resistance characteristics, but difference existed among this isolates. The fourteen endophytic bacteria all had the capacity to produce IAA. Moreover, strains VI₈L₁, VI₈L₂, VI₈L₄, VI₈R₂, VI₈R₃ and II₂R₃ could solubilize Ca₃(PO₄)₂, strains VI₈L₂, II₈L₄ and VI₈R₂ could produce siderophore, and strains VI₈L₂ and VI₈R₃ had the capacity of nitrogen fixation. Both plate and broth assay proved that strain VI₈L₁, VI₈L₂, II₈L₄ and VI₈R₂ were able to effectively solubilize ZnCO₃ and Zn₃(PO₄)₂. The filtrate liquid media after growth of strains VI₈L₁, VI₈L₂, II₈L₄ and VI₈R₂ extracted much higher Zn from artificially ZnCO₃ and Zn₃(PO₄)₂ contaminated soils than those extracted by axenic SMS broth, and the filtrates of the culture media supporting growth of strains VI₈L₂, II₈L₄ and VI₈R₂ also extracted significantly greater quantities of Zn from the Dabaoshan contaminated soils. This Zn mobilizing, plant growth promoting and metal resistant endophytic bacteria may offer promise as inoculants to increase soil Zn bioavailability and improve growth and Zn accumulation by S. alfredii.     

Isolation and characterization of endophytic bacteria from soybean (Glycine max) grown in soil treated with glyphosate herbicide

Endophytic bacteria are ubiquitous in most plant species influencing the host fitness by disease suppression, contaminant degradation, and plant growth promotion. This endophytic bacterial community may be affected by crop management such as the use of chemical compounds. For instance, application of glyphosate herbicide is common mainly due to the use of glyphosate-resistant transgenic plants. In this case, the bacterial equilibrium in plant–endophyte interaction could be shifted because some microbial groups are able to use glyphosate as a source of energy and nutrients, whereas this herbicide may be toxic to other groups. Therefore, the aim of this work was to study cultivable and noncultivable endophytic bacterial populations from soybean (Glycine max) plants cultivated in soil with and without glyphosate application (pre-planting). The cultivable endophytic bacterial community recovered from soybean leaves, stems, and roots included Acinetobacter calcoaceticus, A. junii, Burkholderiasp., B. gladioli, Enterobacter sakazaki, Klebsiella pneumoniae, Pseudomonas oryzihabitans, P. straminea, Ralstonia pickettii,and Sphingomonassp. The DGGE (Denaturing Gradient Gel Electrophoresis) analysis from soybean roots revealed some groups not observed by isolation that were exclusive for plants cultivated in soil with pre-planting glyphosate application, such as Herbaspirillum sp., and other groups in plants that were cultivated in soil without glyphosate, such as Xanthomonas sp. and Stenotrophomonas maltophilia. Furthermore, only two bacterial species were recovered from soybean plants by glyphosate enrichment isolation. They were Pseudomonas oryzihabitans and Burkholderia gladioliwhich showed different sensibility profiles to the glyphosate. These results suggest that the application at pre-planting of the glyphosate herbicide may interfere with the endophytic bacterial communitys equilibrium. This community is composed of different species with the capacity for plant growth promotion and biological control that may be affected. However, the evaluation of this treatment in plant production should be carried out by long-term experiments in field conditions.     

Bt和Bar基因转化对水稻不同组织生态位微生物群落组成及潜在功能影响

【目的】转Bt基因和Bar基因植物的微生态效应是环境安全评价的重要因素,但关于Bt基因和Bar基因转化引起的水稻基因型改变对水稻不同组织生态位微生物群落组成和潜在功能的影响还无系统研究。【方法】以转Bt基因和Bar基因水稻T1C-1及其亲本对照Minghui63为研究对象,基于细菌16S rRNA基因和真菌ITS高通量测序技术,分析抽穗期T1C-1和Minghui63根际土壤微生物以及根、茎、叶内生菌的群落结构和潜在功能。【结果】细菌和真菌群落多样性在水稻不同组织生态位之间发生显著变化,地下部分组织生态位(根际土壤和根系)微生物多样性显著高于地上部分(叶和茎)。T1C-1显著影响叶片内生真菌的香农指数和辛普森指数,而对茎和根的内生菌以及根际土壤微生物多样性无显著影响。叶片内生真菌曲霉菌属(Aspergillus)和篮状菌属(Talaromyces)相对丰度在T1C-1显著增加,推测其参与碳素代谢、能量代谢和转录作用酶合成等过程。T1C-1和Minghui63微生物群落关联网络分析表明,T1C-1的平均聚类系数和平均度显著高于Minghui63,因而T1C-1提高了相关微生物群落网络复杂程度。通过重建未观测状态对群落进行系统发育研究(phylogenetic investigation of communities by reconstruction of unobserved states, PICRUSt2),对叶片内生真菌功能酶基因进行功能预测,相对于Minghui63,T1C-1显著改变了碳素代谢、脂类代谢和能量代谢等途径。【结论】相较于根际土壤,叶片内生真菌的群落组成和潜在功能对T1C-1更敏感。尽管如此,T1C-1并未导致叶片内生真菌的多样性指数降低。为了更准确地评估转基因植物的微生态效应,我们需要加强对不同组织生态位内生菌多样性的关注。     

喀斯特石漠化治理区钙果种植年限对根内细菌群落的影响

存在于健康植物根中的内生细菌不但能够与宿主植物建立共生关系,而且还具有促进植物生长、提升植物对营养元素摄取能力等功能,从而对维持陆地生态平衡、提升喀斯特石漠化综合治理成效具有重要的意义。【目的】探究宿主植物根中的内生细菌群落结构,为深入认识宿主植物-内生细菌的互作机制提供理论依据。【方法】以被引种到喀斯特断陷盆地石漠化综合治理区不同种植年限钙果根中的内生细菌和根际土为研究对象,分析根内生细菌群落特征和根际土理化性质。【结果】钙果种植年限对研究区土壤质量整体有着直接、显著的影响,并间接影响根内生细菌群落。根内生细菌群落以共生互作为主,通过共网络结构识别出种植第一年和第三年的前三位优势属为链霉菌属(Streptomyces)、卡氏伯克霍尔德菌属(Burkholderia-Caballeronia- Paraburkholderia)和噬几丁质菌属(Chitinophaga),种植第五年的前三位优势属为Streptomyces、Chitinophaga和海无柄孢囊黏细菌属(Haliangium)。根内生细菌群落的形成主要由随机性过程中的生态漂变所主导。【结论】不同生长阶段钙果根内生细菌群落结构的差异是由于随机性过程赋予了微生物物种多样化。内生细菌群落的共生互作关系以及优势菌具有生防功能,可增强钙果定殖能力和生长,进而提升钙果在喀斯特断陷盆地石漠化综合治理区的生态效益和经济效益。     

Introduction of some new endophytic bacteria from Bacillus and Streptomyces genera as successful biocontrol agents against Sclerotium rolfsii

Endophytic bacteria live inside plant tissues without causing disease and not only promote plant growth but can also protect plants against plant pathogens. During 2010–2011 crop years, some endophytic bacteria were collected and are then biochemically and molecularly identified (16srRNA) from bean farms of East Azarbaijan, Iran. Among these bacteria isolates, four isolates from Bacillus genera and four isolates from Streptomyces genera were selected for evaluation of their ability for biocontrol of Sclerotium rolfsii in laboratory and glasshouse conditions. Except one isolate named Streptomyces parvus, the rest of isolates could significantly inhibit mycelial growth in dual culture on PDA medium. All seven selected isolates showed significant inhibition in disease treatments in glasshouse experiments. Biological traits, such as length, wet and dry weight of roots and stems in endophytic bacterial treatment showed no differences with healthy control.     

Isolation and characterization of plant growth promoting endophytic diazotrophic bacteria from Korean rice cultivars

We have isolated 576 endophytic bacteria from the leaves, stems, and roots of 10 rice cultivars and identified 12 of them as diazotrophic bacteria using a specific primer set of nif gene. Through 16S rDNA sequence analysis, nifH genes were confirmed in the two species of Penibacillus, three species of Microbacterium, three Bacillus species, and four species of Klebsiella. Rice seeds treated with these plant growth-promoting bacteria (PGPB) showed improved plant growth, increased height and dry weight and antagonistic effects against fungal pathogens. In addition, auxin and siderophore producing ability, and phosphate solubilizing activity were studied for the possible mechanisms of plant growth promotion. Among 12 isolates tested, 10 strains have shown higher auxin producing activity, 6 isolates were confirmed as strains with high siderophore producing activity while 4 isolates turned out to have high phosphate-solubilizing activity. These results strongly suggest that the endophytic diazotrophic bacteria characterized in this study could be successfully used to promote plant growth and inducing fungal resistance in plants.     

香樟产芽孢内生细菌的系统发育多样性

为了解香樟产芽孢内生细菌的多样性,采用改良的NA培养基分离、去除冗余及芽孢染色,得到40株产芽孢内生细菌,占分离所得内生细菌总数的29.9%,其中根、茎、叶中分别分离到25、5和10株。16SrRNA序列系统发育分析结果表明,这40株菌分属于Bacillus、Lysinibacillus、Paenibacillus和Brevibacillus属的12个种;7株菌的16SrRNA部分序列与数据库中模式菌株对应序列相似性小于97%,代表着潜在新类群的存在。同时,3个部位分离出的产芽孢内生细菌既呈现出一定程度的细菌区系相似性,又表现出细菌区系的器官特异性。     

Endophytic fungi from the medicinal plant <Emphasis Type="Italic">Lippia sidoides</Emphasis> Cham. and their antimicrobial activity

Endophytic fungi were isolated from healthy tissues of Lippia sidoides Cham. (Verbenaceae), a medicinal plant used as an antiseptic in the northeast of Brazil. From 480 fragments of leaves (240) and stems (240), a total of 203 endophytic fungi were isolated, representing 14 species belonging to the groups Ascomycota, Coelomycetes and Hyphomycetes. Endophytic colonization was greater in leaves (50.4%) than in stems (35.4%). Colletotrichum gloeosporiodes had the maximum colonization frequency (12.3%), followed by Alternaria alternata (7.08%), Guignardia bidwelli (6.87%) and Phomopsis archeri (5.41%). Some species showed specificity for the host tissue: Curvularia pallescens, Dreschlera dematioidea, G. bidwellii, Microascus desmosporum, Peacilomyces variotti, Periconia byssoides and Ulocladium oudemansii were only isolated from leaves while Fusarium lateritium and Phoma tracheiphila were only isolated from stems. Through a preliminary screening and fermentation assay, 16 isolates where found to produce antimicrobial metabolites against bacterial and fungi. The diversity and role of endophytes in medicinal plants is briefly discussed. In conclusion, endophytic fungi from L. sidoides have pharmaceutical potential and can be seen as an attractive source of biologically active compounds.     

果实红色与黄色番茄品种植株茎部内生细菌群落结构及代谢功能特征

[目的]比较果实颜色分别为红色和黄色的番茄植株茎部内生细菌群落组成及代谢功能特征,旨在探究番茄果色形成与植株内生细菌的关联,为构建番茄育种新型的评价体系,以及开发利用有益微生物功能提供理论依据和技术支撑.[方法]基于MiSeq高通量测序技术,分析果实颜色分别为红色和黄色番茄品种植株茎部内生细菌群落组成及相关代谢功能生物...     

广西葛根内生细菌的分离鉴定及其促生特性

【背景】植物内生菌长期与宿主共生,对宿主生长发育产生影响。葛根作为重要的药食两用作物,葛根内生菌的研究具有重要实践意义。【目的】对广西葛根根部内生细菌进行分离、鉴定及促植物生长特性分析,旨在了解该药食同源植物内生细菌种群结构及其促生特性,为分析内生菌群体在药食同源植物产量和品质形成的作用及其内生细菌资源的开发利用提供参考。【方法】采用6种不同的培养基从广西葛根的根瘤、根系和根愈伤组织分离内生细菌,16S rRNA基因测序和系统发育分析内生细菌的分布特征和遗传多样性,采用生理生化方法测定分离菌株的固氮活性、溶磷特性、产生嗜铁素、分泌吲哚乙酸(indole-3-aceticacid,IAA)等促生特性。【结果】从葛根根瘤、根系和根部愈伤组织中共分离得到223个菌株,16S rRNA基因测序鉴定这些菌株隶属于2门4纲10科19属,其中芽孢杆菌属、假单胞菌属、土壤杆菌属、肠杆菌属为葛根优势菌群;内生细菌数量和群落组成存在明显的组织特异性,其数量表现为根瘤>根系>根愈伤组织,但其种群多样性表现为根愈伤组织>根系>根瘤。不同培养基分离出的细菌种群丰富度有差异。从供试菌株中筛...     

不同栽培方式的铁皮石斛根、茎中内生细菌多样性及其抑菌活性研究

[目的] 分析树干仿生栽培和大棚种植的铁皮石斛根、茎中内生细菌的组成与分布,并挖掘潜在的微生物资源及功能。[方法] 利用Illumina MiSeq高通量测序技术,对不同栽培方式铁皮石斛根、茎中免培养内生细菌丰富度及多样性进行比较分析;通过传统的内生菌分离法以及16S rRNA基因测序技术对可培养内生细菌进行分离鉴定;采用滤纸片法筛选拮抗石斛病原菌的内生菌株。[结果] 高通量测序分析中内生细菌以Pseudomonas （30.52%）为主,其次是Mycobacterium （10.22%）以及Brachybacterium （8.32%）,树干仿生栽培石斛内生细菌组成丰富度及多样性高于大棚种植,石斛根中内生细菌组成丰富度及多样性高于石斛茎。可培养内生细菌中Bacillus （18.37%）所占比例最高,其次是Curtobacterium （8.16%）,同时筛选得到8株具有抑制石斛病原菌活性的菌株。[结论] 铁皮石斛中蕴含着丰富的内生细菌资源,菌群组成和分布受其不同栽培方式和组织部位的影响。此外,筛选得到8株具有抑制病原菌活性的菌株,表明铁皮石斛内生细菌代谢产物具有抗菌活性。本试验对铁皮石斛内生细菌多样性及其抑菌活性的分析研究,为石斛内生微生物资源的后续深度挖掘以及利用提供了内生细菌资源。     

黑老虎内生真菌及根际土壤真菌的群落结构与生态功能分析

为探讨黑老虎(Kadsura coccinea)根际土壤和组织内生真菌菌群的组成及其生态功能，该研究采用ITS高通量测序技术对成熟黑老虎(根、茎、叶)内生真菌及根际土壤真菌群落结构、多样性和生态功能进行了分析。结果表明：(1)从12个样品中共获得2 241个可操作分类单元(OTU),涉及10门、41纲、95目、212科、367属，内生真菌(根、茎、叶)和根际土壤真菌OTU数分别为386、536、258、1 435个，其中共有的OTU为18个。在门水平上，黑老虎内生真菌及根际土壤真菌优势群落均为子囊菌门和担子菌门，其中子囊菌门在叶和茎中占比分别高达96.99%和95.37%;在属水平上，黑老虎根际土壤真菌中腐生真菌被孢霉属占比较高(为13.5%),叶和茎等生长旺盛的组织中子囊菌门未分类属和痂囊腔菌属占比较高。(2)α多样性分析结果显示，黑老虎根际土壤真菌群落的丰度和多样性明显高于内生真菌，茎中内生真菌丰度显著高于根和叶，而根、茎和叶组织间内生真菌多样性差异不显著；PCoA分析结果显示，叶和茎的真菌群落结构相似性更高。(3)利用FUNGuild数据库进行的功能预测分析结果显示，黑老虎根际土...