剑叶龙血树内生真菌的分离及体外抑菌活性筛选

为研究剑叶龙血树内生真菌资源多样性,初步探讨和筛选具有抑菌活性的特异性菌株以及进一步开发剑叶龙血树内生真菌的抗菌活性化合物。该文采用植物组织分离法从剑叶龙血树茎和叶中分离内生真菌,对内生真菌进行液体发酵7 d,经乙酸乙酯萃取后制得粗提物,并采用牛津杯扩散法,以10种常见病原菌和5种临床耐药菌为靶标检测其发酵粗提物的抑菌活性,对有较好抑菌活性的内生真菌进行分子鉴定。结果表明:(1)从剑叶龙血树茎、叶中共分离得到345株内生真菌,294株对一种以上指示菌有抑制活性;(2)其中84株内生真菌对5株临床耐药菌均有不同程度的抑制活性,占所分离菌株总数的24.35%,75%的内生真菌对金黄色葡萄球菌有抑制活性。这说明剑叶龙血树中存在多种有抑菌活性的内生真菌,为剑叶龙血树内生菌抗菌活性成分挖掘及新型抗菌药物筛选奠定了基础。     

几种热带观叶植物的组织培养

植物名称:1.剑叶朱蕉(corsyline fruticosa)2.柬埔寨龙血树(Dracaena cambodiana)3.越南龙血树(Dracaenasp.)4.金心龙血树(D.fragra-ns var.massangana)5.金边龙血树(D.fragransvar.victoria)6.非洲龙血树(D.draco)7.山花龙血树(D.elliotica)。材料类别:直径1.5—2cm未木质化茎段切成2mm厚的切片。     

龙血树真菌群及其对血褐形成的影响

从柬埔寨龙血树茎杆中分离到３０３株真菌,其中镰刀菌属菌株占总分离频率的５２％,其次是短梗霉和枝孢霉。通过活体接种对血竭产生的影响试验表明,对血竭形成起重要作用的真菌主要是禾谷镰刀菌龙血树变种等４株红色镰刀菌,可使血竭形成量提高６６％－１２０％。     

产黄酮甘蔗叶内生真菌的分离与鉴定

采用显色反应、薄层层析色谱和紫外吸收光谱法,对甘蔗叶内16株内生真菌的代谢产物进行黄酮类化合物检测。结果共筛选到3株能够产黄酮类化合物的内生真菌(GZ-1、GZ-4和GZ-5)。依据真菌的形态特征及ITS序列分析,鉴定结果表明菌株GZ-1、GZ-5为棘孢曲霉(Aspergillus aculeatus),菌株GZ-4为黑曲霉(Aspergillus niger)。     

蛇菊中所含的黄酮类化合物

蛇菊(Stevia rebaudina)是一种木质草本植物,原产于巴拉圭。目前由于市场的要求,许多国家和地区都在种植。在学术研究上以及在商业上,人们对于蛇菊的兴趣主要集中在蛇菊的甜味双萜上,它占干叶的5—10％。虽然有的研究人员已开始注意它所含有的黄酮类化合物,但到目前为止,关于黄酮类化合物的实验报告只谈到从中离析出了5,6二羟基7,8,4＇     

解淀粉芽孢杆菌MN-8对玉米秸秆木质纤维素的降解

微生物降解木质纤维素既是生物质资源化利用中的关键问题,也是亟需解决的难点问题.本文在前期获得木质素降解菌——解淀粉芽孢杆菌MN-8菌株的基础上,进一步研究该菌株对玉米秸秆木质纤维素的降解作用.研究利用玉米秸秆粉-MSM培养基对MN-8菌株进行固态发酵,监测发酵过程中木质纤维素酶活力和木质纤维素含量变化情况,并通过傅立叶红外光谱(FTIR)和气质联用色谱(GC/MS)对木质纤维素的降解情况及产物进行分析.结果表明:解淀粉芽孢杆菌MN-8菌株可产生木质素过氧化物酶、锰过氧化物酶、纤维素酶和半纤维素酶等木质纤维素降解酶,在发酵10～16 d陆续达到酶活力峰值,最高酶活力分别为55.0、16.7、45.4和60.5 U·g-1.发酵24 d后,玉米秸秆中木质素、纤维素和半纤维素的降解率可分别达到42.9％、40.6％和27.1％.FTIR光谱数据表明,玉米秸秆发酵后木质素、纤维素和半纤维素的特征吸收峰强度均有一定程度的下降,表明木质纤维素被部分降解.GC/MS分析结果也证实,解淀粉芽孢杆菌MN-8能有效降解秸秆木质纤维素.MN-8菌株可断裂玉米秸秆木质素单体之间的连接键β-O-4,将秸秆木质素解聚为苯丙胺、苯丙酮和苯丙酸等保留木质素苯丙烷结构的单体化合物,并将部分单体化合物进一步氧化为Cα羰基化合物,如2-氨基-1-苯丙酮和紫丁香基苯乙酮等.在对纤维素和半纤维素降解产物的GC/MS分析中发现,降解产物包含葡萄糖、甘露糖和半乳糖等多种单糖化合物以及甲酸、乙酸、丙酸、1,1-乙二醇和3-羟基丁酸等代谢产物.表明解淀粉芽孢杆菌MN-8对秸秆木质纤维素表现出强降解作用,且该作用依赖于菌株产木质纤维素降解酶的能力.     

龙血之乡话龙血

正谁持玉带山间舞?盘曲虬枝龙血树。果粒橙红如赤豆,种实剔透赛珍珠。万年寿圣传神话,千载国医化血瘀。止血消炎拥特效,云南红药见功夫!这首小诗写的是一种叫龙血树的植物。龙血树隶属于百合科龙血树属(Dracaena L.),该属植物为乔木状或灌木状,茎多少木质,有髓和次生形成层,常具分枝。叶片剑形、倒披针形或其他形状,常聚生于茎或枝的顶端或最上部。     

产杜仲黄酮内生真菌的初步研究

由杜仲植株的根、茎、叶分离到内生真菌,分别对各菌株进行液体培养,筛选能产生与杜仲药材相同或相似黄酮类化合物的内生真菌。将培养物适当处理后,根据黄酮类化合物所特有的颜色反应进行初筛,然后根据TLC分析和紫外-可见光分光光度法测定结果进行复筛,结果从杜仲植株共分离得到44株内生真菌,其中1株(DZY5)能产出与其宿主相同或相似的黄酮类物质。     

微生物合成黄酮类研究进展

黄酮类化合物是植物特有的多酚类化合物,具有抗氧化、抗炎、抗肿瘤、改善血液循环等生理功能,在保健品、化妆品和医药等方面具有广阔的应用前景。黄酮类化合物主要通过植物提取制备,受时间空间及植物种类等因素限制,且分离纯化步骤复杂,产率较低。随着合成生物学与代谢工程的发展,构建黄酮类物质的生物合成代谢途径线路,并对基因来源、基因序列、基因组合方式、菌株底盘改造等方面进行筛选和优化已取得较大成果。现已能用工程酵母和大肠杆菌等微生物合成二氢黄酮、黄酮、异黄酮、黄酮醇、花色素和黄烷酮等黄酮类化合物,在此基础上还可经甲基化酶或糖基化酶修饰,增加新的生物活性。综述了目前国内外微生物合成各类黄酮类物质的研究进展,并对将来的发展趋势进行了讨论和分析。     

黄酮化合物色谱保留时间与其三维结构的关系研究

利用比较分子相似性指数分析（CoMSIA）方法,结合黄酮类化合物含有较多羟基、易形成较强分子内氢键的特点,建立了黄酮类化合物色谱保留时间与其三维结构的关系模型,以探讨黄酮类化合物色谱保留时间预测的新方法。模型交叉验证相关系数q2值为0．705,非交叉验证相关系数r2为0．981,表明模型具有较好的预测能力。该研究结果对进一步开展黄酮类化合物液相色谱保留参数与三维结构关系的研究提供了思路和方法。     

9568D镰孢霉作用于死态龙血树形成血脂的研究

1　引　　言剑叶龙血树血竭来自于剑叶龙血树 (Ｄｒａｃａｅｎａｃｏｃｈｉｎｃｈｉｎｅｎｓｉｓ)的树脂 ,早年的研究[[2 ] 发现人工割伤可以促进树脂的积累 .江东福等[4] 证实剑叶龙血树血竭的形成与真菌相关 ,用特异性真菌接种活体龙血树 ,激活龙血树的防御反应 ,产生含植物防卫素的血竭[1,3 ,6] .但人们注意到野外自然环境下一些衰老枯死的剑叶龙血树的材质上亦有血竭形成 ,其与真菌的作用是否有关联 ?本文采用分离自剑叶龙血树根部的内生真菌 95 6 8Ｄ镰孢霉接种于剑叶龙血树材质(经灭活处理 ) ,保湿培养 4～ 5个月后 ,在接种部位有红色…     

Rhizobium Strain Effects on Nitrogen Transport and Distribution in Soybeans

Neves, M. C. P, Didonet, A. D., Duque, F. F. and Dobereiner,J. 1985. Rhizobium strain effects on nitrogen transport anddistribution in soybeans.—J. exp. Bot. 36: 1179–1192. The role of six Rhizobium strains in the nitrogen metabolismof soybeans (Glycine max Merril) was studied under glasshouseand field conditions. The strains could be divided into twogroups, group I which produced a large nodule mass with relativelylow efficiency and group II which produced less nodule massbut which fixed the same amount of nitrogen. Plants inoculatedwith group I strains remobilized nitrogen faster from leavesbut also lost more nitrogen in senesced leaves. Although thetotal nitrogen transported in the xylem was similar for allstrains, plants inoculated with group I strains contained lessnitrogen in ureides in the xylem sap during the whole growthcycle. This difference was reflected in the nitrogen partitioningwithin the shoot, and smaller nitrogen harvest indexes wereobserved in these plants than in those inoculated with strainsof group II. The role of ureides in the nitrogen partitioningand grain yield was confirmed by the significant correlationbetween mean ureide content in xylem sap and nitrogen partitioningor yield. Further, nodules formed with group I strains evolvedmore hydrogen than those formed with group II strains and thepossible significance of this is discussed. Key words: Ureides, hydrogen evolution, grain yield, grain yield, harvest index, nitrogen fixation     

乳酸产生菌的选育

从5种菌株中,通过初筛和复筛筛选出一种变色范围大,产乳酸量高的菌株D(产酸量为69.36g/L),以此菌株作为出发菌,进行紫外诱变育种。从诱变处理后的计数平板上,选取10株hc值大的菌株,通过复筛最终选出了一株平均产乳酸量高的菌株D_6,其产乳酸量平均为71.73 g/L,比出发菌株高出2.37g/L。     

Strains inside xylem and inner bark of a stem submitted to a change in hydrostatic pressure

Tangential strains were measured with strain gauges at the surface of xylem and inner bark of saplings of Cryptomeria japonica D. Don. and Fagus silvatica L. during a pressurization test. The test consists in submitting the whole sapling to an artificially imposed hydrostatic pressure of increasing magnitude. The elastic response of the stems was found linear both at the surface of xylem and inner bark. A simple geometric model allows to compute radial strains in each tissue from tangential strain data. Inside inner bark, radial strains are much larger than tangential strains, because tangential strains are restrained by the core of wood. The material compliance of each tissue was computed as the ratio between the radial strain and the pressure that caused it. The material compliance of xylem is much lower than that of inner bark, but, as its thickness is much larger, its contribution to the apparent behavior of the stem is not negligible. Computation of material compliances by this pressurization test provides information about the specific behavior of each tissue in response to hydrostatic pressure. This can be used to estimate and interpret the calibration factor linking the water status of the plant to the apparent strain measured at its surface.T. Okuyama: deceased     

A Pectinase-deficient Ralstonia solanacearum Strain Induces Reduced and Delayed Structural Defences in Tomato Xylem

It has been suggested that oligogalacturonides (OGAs) released by bacterial pectinases can induce plant defence responses. To test this hypothesis, resistant tomato cultivar LS-89 and susceptible cultivar Ponderosa were inoculated with either wild-type Ralstonia solanacearum strain K60 or a pectinase-deficient triple mutant K60-509, which lacks endo-polygalacturonase PehA, exo-poly-alpha- d -galacturonosidase PehB, and pectin methylesterase Pme. K60 induced structural defence responses, including electron-dense materials (EDMs) in vessels and apposition layers (ALs) in parenchyma cells adjacent to xylem vessels colonized by bacteria in LS-89 stems. In contrast, LS-89 infected with K60-509 did not have any EDMs in vessels at 4 days after inoculation (DAI), and had them only rarely at 7 DAI. In LS-89 infected with K60-509, ALs were rarely observed in parenchyma cells adjacent to vessels at 4 DAI, and while they were present at 7 DAI, they were thinner than ALs induced by K60. The bacterial density in LS-89 stems infected with K60-509 was lower than in stems infected with K60 at 4 DAI, but the strains reached similar population sizes by 7 DAI, showing the pectinase-deficient mutant colonized resistant stems more slowly than did the wild-type strain. Vessels infected with K60-509 contained fewer EDMs at 7 DAI than were observed at either 4 or 7 DAI in vessels colonized by K60, although bacterial density in the xylem tissues containing K60-509 at 7 DAI was about the same as in the xylem tissues containing K60 at 4 DAI. Neither the wild-type strain nor the pectinase-deficient mutant induced these histopathological changes on susceptible cultivar Ponderosa. These results indicate that R. solanacearum pectinases play some role in eliciting histopathological changes in LS-89, likely by releasing OGAs that trigger plant structural defences.     

生物絮凝剂产生菌的分离与鉴定

通过多点采样,多次反复筛选,从旱田土壤中筛选出1株具有高絮凝活性的细菌。细菌生长过程均可产生具有絮凝作用的胞外分泌物,经实验对内蒙天然碱碱泥具有高絮凝作用。通过对菌株的个体形态特征、菌落形态特征、运动性进行观察;同时对其接触酶、氧化酶等生理生化指标进行了测试,最终确定为粪产碱杆菌（Alcaligenes faecalis)。     

一株分离于工业污水池的耐碱酵母

目的:从新疆温泉县一个碱性工业污水处理池中分离并鉴定耐碱酵母菌。方法:用稀释平板法分离菌种,通过形态学观察、生理生化特征及26S rDNA D1/D2区基因序列分析鉴定菌种。结果:从水样中分离得到一株耐碱酵母菌,它们能在pH3.5~11.0,12%NaCl,4~45℃生长,经形态观察及生理生化特征鉴定为酵母属,对其26S rDNA 5’端D1/D2区基因序列进行了PCR扩增并测序,GenBank注册号为DQ132884,同源序列分析结果表明该序列与酿酒酵母(Saccharomyces cerevisiae)Sb4有99.8%的同源性,因此将其命名为酿酒酵母(Saccharomyces cerevisiae)XJU-2,该菌种已保藏于中国微生物菌种保藏委员会普通微生物中心(CGM-CC),保藏号为CGMCC No.2.3095。结论:XJU-2的最高耐碱值可达pH 11.0,而且酸碱耐受范围很大,性能明显优于国内外已报道的酿酒酵母菌种。     

渤海湾仿刺参养殖圈内贝莱斯芽胞杆菌B-VE的分离鉴定及其产抗菌脂肽的研究

为分离筛选具有广谱抑菌作用的细菌并研究其抗菌物质,实验利用琼脂扩散法和牛津杯法,以溶壁微球菌、金黄色葡萄球菌、铜绿假单胞杆菌、大肠埃希菌为指示菌,从渤海湾大连海域仿刺参养殖圈中分离筛选出9株活性菌,2株具有广谱抑菌效果,其中1株抑菌效果最强。通过形态学和分子生物学检测分析,鉴定该菌株为贝莱斯芽胞杆菌(Bacillus velezensis),命名为B-VE。通过酸沉法分离发酵液中的抑菌物质,利用飞行时间质谱对其分子量进行检测,初步确定其隶属于抗菌脂肽类物质,抑菌物质包括的三种物质分别为伊枯草菌素(Iturin)、芬荠素(Fengycin A)和杆菌霉素(Bacillomycin D)。实验发现该抗菌脂肽类粗提物具有较强的pH和温度耐受性,可以耐受多种蛋白的酶解作用,且在多种有机溶剂中可以保持较强的抑菌效果。利用扫描电镜检测发现其主要通过破坏细菌的细胞膜对溶壁微球菌产生抑菌作用。结果表明,贝莱斯芽胞杆菌B-VE广谱抑菌,所产抗菌脂肽对细菌具有较强的破膜作用,且理化性质稳定,具有较好的开发利用价值。     

高温链霉菌24＃的初步研究

从土壤中筛选得到一株产广谱、高活性抗真菌物质的链霉菌 2 4 # ,经测定对 2 5种植物病原真菌有显著拮抗作用 ,其次生代谢产物对病菌菌丝有断裂、扭曲、缢缩等致畸效应。 16SrDNA序列分析显示本菌株与模式菌株链霉菌DSM4 4 2 93T的 16SrDNA同源性为 98 93% ,但菌株形态特征、培养特征、细胞壁化学组分、生理生化特性等均不同于模式菌株 ,且DNA杂交率只有 2 2 5 4 % ,建议为链霉菌属的一个新种 ,命名为山东链霉菌 (Streptomycesshandon gensissp .nov .)。     

一株溶藻细菌NP23的初步分离鉴别及其溶藻作用研究

从水体中分离得到一株具有溶藻能力的细菌,命名为NP23。经形态特征、生理生化鉴定和16S rDNA序列分析表明,该菌株属于肠杆菌属(Enterobacter)。研究了该菌株对湖泊中优势藻的溶藻效果,初步探讨了其溶藻方式及溶藻物质。结果表明,该菌株对小球藻、惠氏微囊藻、栅藻和蛋白核小球藻具有一定的去除效果,叶绿素a的去除率分别为64.1%、53.1%、87.2%和84.4%,而且在10-108CFU/mL菌浓度范围内,藻的去除率与菌液的浓度成正相关;该菌株对小球藻、栅藻和蛋白核小球藻是间接溶藻,对惠氏微囊藻是直接溶藻;该菌株对栅藻的溶藻物质是蛋白类物质,对蛋白核小球藻的溶藻因子是菌体胞外分泌的具有热稳定性的非蛋白类物质。