异育银鲫肠道蛭弧菌的分离及其生物学特性的研究

以一株具有致病力的温和气单胞菌作为筛选宿主菌,从异育银鲫肠道中分离到一株蛭弧菌,暂命名为BDF-H16。通过光学显微镜、相差显微镜、电子显微镜对蛭弧菌BDF-H16进行形态观察,并研究了其部分生物学特性。结果表明:蛭弧菌BDF-H16为革兰氏阴性菌,杆形或弧杆形,端生一根鞭毛,菌体大小多为0．2μm～0．5μm×0．8μm～1．2μm;蛭弧菌BDF-H16对实验所选用的革兰氏阴性菌和部分革兰氏阳性菌均有裂解作用;以大肠杆菌为宿主菌,其最佳生长条件为宿主菌浓度6．75×10~9cfu/mL、pH7．0～7．5、温度28℃;在NaCl含量0．85%～5．00%的培养基中能够生长;恩诺沙星、诺氟沙星对其有抑制作用。     

恩诺沙星对蛭弧菌生长及吸附的影响

本实验通过观察不同浓度恩诺沙星对固体培养条件下蛭弧菌产生噬斑和液体培养条件下蛭弧菌增殖的情况,以及蛭弧菌在不同浓度恩诺沙星下吸附到载体上的情况,研究了恩诺沙星对蛭弧菌BDF-H16生长及吸附的影响.实验发现:2μg/mL、5μg/mL、10μg/mL、20μg/mL和50μg/mL恩诺沙星对蛭弧菌BDF-H16噬斑的产生及增殖均具有抑制作用(P<0.05).在固体培养72 h后.随着恩诺沙星浓度逐渐增大,蛭弧菌BDF-H16产生的噬斑数目逐渐减少;在液体培养72 h后,随着恩诺沙星的浓度逐渐增高,蛭弧菌BDF-H16的增殖浓度不断减少,但10μg/mL恩诺沙星并没有改变蛭弧菌BDF-H16的生长趋势.此外,以沸石作为吸附载体,2μg/mL、5 μg/mL、10 μg/mL、20 μg/mL和50 μg/mL恩诺沙星降低了蛭弧菌BDF-H16吸附量,随着恩诺沙星浓度的增大,蛭弧菌BDF-H16的吸附量逐渐降低,而蛭弧菌BDF-H16的吸附率却在一定恩诺沙星浓度(2 μg/mL～20μg/mL)下却有所升高(P<0.05).以上结果表明,恩诺沙星对蛭弧菌BDF-H16噬斑的产生及增殖具有抑制作用,但在有载体存在的情况下,蛭弧菌的吸附能力在一定恩诺沙星浓度范围内有所增强,添加载体沸石有助于降低恩诺沙星对蛭弧菌BDF-H16的不良影响.     

人粪便中分离的噬菌蛭弧菌生物学特性的研究

本文研究了人粪便中分离的噬菌蛭弧菌的生物学特性,测定了它们的生长曲线,并利用微孔滤膜过滤和机械振荡的方法,研究了它们的吸附和穿入动力学,发现链霉素、庆大霉素和卡那霉素能抑制蛭弧菌的吸附;青霉素不影响蛭弧菌的吸附和穿入,但抑制蛭弧菌在宿主内的生长过程。从人粪中分出的噬菌蛭弧菌不仅能裂解大部分需氧的革兰氏阴性菌,而且在微氧条件下也能裂解厌氧菌中的二株脆弱拟杆菌。我们发现一株人粪便中分出的噬菌蛭弧菌能形成蛭弧菌囊体——它的休眠态,它对高热、紫外线照射和真空干燥的耐受力较相应的繁殖体强,看来它是蛭弧菌保持生命期限的一种方式。     

蛭弧菌Bdh5221株理化特性和16S rDNA序列分析

蛭弧菌海水菌株Bdh5221于2005年8月从海南琼海对虾养殖场周边排水沟水样中分离所得,具有裂解多数革兰氏阴细菌的特性.在前期Bdh5221噬菌谱研究的基础上,利用其可利用热致死革兰氏阴细菌的生长特性,对其理化特性、药敏特性和16S rDNA序列分析进行了相关研究.结果表明:该株蛭弧菌为革兰氏阴性菌,呈杆状、弧状,一端有极长的极生鞭毛,细菌大小在(0.2-0.5)μm×(0.6-1.5)μm左右;生化实验表明:Bdh5221明胶穿刺试验和接触酶试验呈阳性,氧化酶反应呈阴性,对弧菌抑制剂O/129敏感;药敏实验表明:此菌对新霉素、卡那霉素、恩诺沙星敏感,对青霉素、磺胺啼啶和万古霉素不敏感;对其16S rDNA序列的测定、分析表明,与其同源性最高的细菌是一株新发现的海洋新种细菌Kordiimonas gwangyangensis,同源性高达99%,而与其他蛭弧菌属细菌的同源性从90%到70%不等,并针对其基因序列做了相关进化分析.     

蛭弧菌的分离及其生长条件和裂解能力的研究

噬菌蛭弧菌具有裂解病原菌、净化水体的功效,从海洋环境中分离到4株Bh04系列蛭弧菌,对其生长条件进行了测定,同时研究了它们对61株菌株的裂解能力。结果表明,在1%～3%的盐度范围内,蛭弧菌均可生长,最适盐度为3%;在15～30℃温度条件下蛭弧菌也可生长,但最适培养温度为20-25℃;只有在使用活的宿主菌的培养条件下,蛭弧菌才能生长。4株蛭弧菌分别可裂解21、24、40、43株菌,各占总试验菌数(61)的34.4%、39.3%、65.6%和70.5%。4株蛭弧菌一起,则可裂解55菌株,占总试验菌株的90.2%。研究结果揭示了蛭弧菌在消除海洋环境中有害细菌方面的潜在应用价值。     

两株海洋蛭弧菌的分离及生物学性质

[目的]从深圳湾海泥中分离鉴定蛭弧菌,并对其生物学性质进行初步研究.[方法]通过稀释营养肉汤(dilute nutrient broth,DNB)双层平板法分离蛭弧菌,对所分离的菌株进行电镜形态观测,并进行16S rDNA测序分析,之后结合1994年版伯杰氏鉴定细菌学手册对菌株进行鉴定,最后通过生理试验对其生物学性质进行研究.[结果]从深圳湾海泥中分离出2株蛭弧菌,分别命名为5#-12和5#-sh06,它们可在20℃～35℃范围内生长,最适温度分别是25℃和30℃;生长pH范围6.1～8.6,最适pH均为7.2;2株蛭弧菌可分别裂解46和48株试验菌,各占总试验菌株数(58)的79.3%和82.8%;联合2株蛭弧菌,可裂解56株试验菌,占总试验菌株数的96.6%;同时,它们一起能将所有试验弧菌裂解.[结论]研究结果揭示了蛭弧菌作为一种生物净化因子具有极大的潜在应用价值.     

噬菌蛭弧菌对鱼类常见致病菌裂解作用的研究

调查了北京地区２５份水样,其中２４份检出噬菌蛭弧菌。本次试验选用４株鱼类主要致病菌为宿主菌,检出的蛭弧菌对上述４种细菌的裂解范围有所不同。其中嗜水气单胞菌可被全部检出的蛭弧菌裂解（２４／２４）,其他３株菌仅部分被裂解,依次为肠型点状气单胞菌（１７／２４）,荧光假单胞菌（９／２４）,鳗弧菌（７／２４）。本次试验直接从水样中检出６株对４种宿主菌均有裂解作用的蛭弧菌,为进一步利用蛭弧菌防治鱼类常见细菌性疾病提供了可用资料。     

噬菌蛭弧菌对鱼类常见致病菌裂解作用的研究*

调查了北京地区２５份水样,其中２４份检出噬菌蛭弧菌。本次试验选用４株鱼类主要致病菌为宿主菌,检出的蛭弧菌对上述４种细菌的裂解范围有所不同。其中嗜水气单胞菌可被全部检出的蛭弧菌裂解（２４／２４）,其他３株菌仅部分被裂解,依次为肠型点状气单胞菌（１７／２４）,荧光假单胞菌（９／２４）,鳗弧菌（７／２４）。本次试验直接从水样中检出６株对４种宿主菌均有裂解作用的蛭弧菌,为进一步利用蛭弧菌防治鱼类常见细菌性疾病提供了可用资料。     

海洋蛭弧菌的分离鉴定及其对副溶血弧菌的作用

蛭弧菌广泛存在于自然水体, 具有噬菌的特性, 对水体中细菌数量控制具调节作用。以副溶血弧菌为宿主菌, 利用双层琼脂法, 从海洋水体中分离出15株具有噬菌作用的细菌, 对形成噬菌斑能力最强的1株菌株进行特异性16S rDNA扩增, 确认为蛭弧菌, 命名为Bd-M1。Bd-M1对大多数海水养殖动物病原菌有裂解作用, 裂解率在90%(20/22)以上, 模拟水环境实验发现, 蛭弧菌对副溶血弧菌有较强的裂解和净化作用, 102 h内能使副溶血弧菌从3.0′108 CFU/mL下降到8.7×103 CFU/mL。动物实验表明蛭弧菌能有效预防对虾弧菌病的发生, 表明蛭弧菌有望成为水产动物疾病防治的一种有效的生物制剂。     

蛭弧菌BDE-1的生物特性及促进其蛭质体形成的研究

【背景】蛭弧菌是众多海洋益生菌中的一类较新成员,应用前景十分广阔。但由于蛭弧菌特殊的繁殖方式和周期,它的应用效果受寄生宿主特性和生物活性的影响,因而优选寄生宿主,维持或者提高蛭弧菌微生态制剂的应用活性是关键。【目的】筛选出能够裂解枯草芽孢杆菌的蛭弧菌,以增进其益生性能;研究提高蛭弧菌的蛭质体密度,以利于保存。【方法】从海南取回海泥样后,以枯草芽孢杆菌作为宿主菌,通过稀营养肉汤(Dilute nutrient broth,DNB)双层平板法分离获得蛭弧菌,并对目标菌株进行透射电镜形态鉴定和16S rRNA基因序列分析;然后进行生物学特性研究,同时开展氨苄青霉素、吲哚、Ca~(2+)和Mg~(2+)影响蛭质体形成的研究。【结果】分离出一株以枯草芽孢杆菌作为宿主的蛭弧菌并命名为BDE-1,其最适温度、盐度和pH分别为25℃、2.0%和7.0;BDE-1可裂解24株试验菌,占总试验菌株数(28株)的85.7%,其中对试验弧菌(13株)的裂解率达92.3%;吲哚、氨苄青霉素、Ca~(2+)和Mg~(2+)4种因子对BDE-1蛭质体的形成均有促进作用,其中吲哚和Ca~(2+)的促进作用显著。【结论】研究结果不仅为蛭弧菌寄生宿主的优化选择提供了可行性解决思路,而且为维持或提高蛭弧菌微生态制剂的应用活性提供了理论依据。     

In vitro propagation of <Emphasis Type="Italic">Helleborus</Emphasis> species

A general in vitro cloning system was established for four Helleborus species: H. argutifolius, H. foetidus, H. niger and H. orientalis. The plant material was introduced in vitro from axillary buds. A Murashige and Skoog (MS)—based medium (Murashige and Skoog 1962) was used supplemented with 2% (w/v) sucrose, 2-isopentenyladenine (2-iP) and 6-benzylaminopurine (BA). Multiplication rates depended on the genotype and varied from 1.3 for H. foetidus till 3.8 for H. niger. The first results showed that the rooting phase could be done ex vitro. Rooting was induced by a drench for one week in a solution of indole-3-butyric acid (IBA -3 mg l⁻¹) and 1-naphthaleneacetic acid (NAA-1 mg l⁻¹) at 5°C.     

A new name in <Emphasis Type="Italic">Pavetta</Emphasis> L. (<Emphasis Type="Italic">Rubiaceae</Emphasis>)

Summary  The name Pavetta modesta (Hiern) S. E. Dawson is a later homonym of P. modesta Bremek. Pavetta crystalensis is proposed as a new name.     

Effects of vapour pressure deficit on growth of temperate and tropical evergreen rainforest trees of Australia

Little is known about the effect of vapour pressure deficit (VPD) on the growth of trees. Rainforest trees of eastern Australia provide an opportunity to investigate responses to VPD in species that occur in high precipitation areas but have contrasting dry seasons—summer in the temperate south and winter in the tropical north. Growth responses to VPD were measured in eight species of Australian rainforest trees from different latitudes to investigate possible differences in their response to atmospheric drought. Previous work on these species found that the tropical species have large reductions in gas exchange with increasing VPD whereas the temperate species were mainly unresponsive to increasing VPD. Plants were grown in glasshouses for a year under either low VPD or ambient conditions of a temperate climate. All species had non-significant increases in growth rates (1–9%) of plants grown under low VPD compared with plants grown under ambient VPD. In addition, growing the species under low VPD had no effect on allocation of biomass (leaf area ratio, leaf weight ratio and root/shoot ratio). Therefore, the high sensitivity of gas exchange to increasing VPD found in the tropical rainforest trees did not have a significant, long-term effect on growth under high VPD.     

Novel<Emphasis Type="Italic"> eceriferum</Emphasis> mutants in<Emphasis Type="Italic"> Arabidopsis thaliana</Emphasis>

We conducted a novel non-visual screen for cuticular wax mutants in Arabidopsis thaliana (L.) Heynh. Using gas chromatography we screened over 1,200 ethyl methane sulfonate (EMS)-mutagenized lines for alterations in the major A. thaliana wild-type stem cuticular chemicals. Five lines showed distinct differences from the wild type and were further analyzed by gas chromatography and scanning electron microscopy. The five mutants were mapped to specific chromosome locations and tested for allelism with other wax mutant loci mapping to the same region. Toward this end, the mapping of the cuticular wax (cer) mutants cer10 to cer20 was conducted to allow more efficient allelism tests with newly identified lines. From these five lines, we have identified three mutants defining novel genes that have been designated CER22, CER23, and CER24. Detailed stem and leaf chemistry has allowed us to place these novel mutants in specific steps of the cuticular wax biosynthetic pathway and to make hypotheses about the function of their gene products.Abbreviations EMS Ethyl methane sulfonate - SEM Scanning electron microscopy - SSLP Simple sequence length polymorphism - WT Wild type     

Synergistic effect between dieckol from <Emphasis Type="Italic">Ecklonia stolonifera</Emphasis> and β-lactams against methicillin-resistant <Emphasis Type="Italic">Staphylococcus aureus</Emphasis>

We have been attempting for some time to discover a compound evidencing antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA). The dieckol isolated from Ecklonia stolonifera has been shown to exhibit antibacterial activity against methicillin-susceptible S. aureus (MSSA) and MRSA. The minimum inhibitory concentrations (MICs) of dieckol were determined in a range of 32 to 64 μg/mL against standard MSSA and MRSA strains. Furthermore, dieckol clearly reversed the high-level ampicillin and penicillin resistance of MRSA. The MICs of ampicillin against two standard strains of MRSA were dramatically reduced from 512 to 0.5 μg/mL in combination with 1/4 MIC of dieckol (16 μg/mL). The fractional inhibitory concentration (FIC) indices of ampicillin and penicillin were measured from 0.066 to 0.266 in combination with 8 or 16 μg/mL of dieckol against all tested MRSA strains, thereby suggesting that dieckol-ampicillin or dieckol-penicillin combinations exert a synergistic effect against MRSA. The results of this study indicate that dieckol, administered in combination with β-lactams, may prove effective in the treatment of MRSA infections. Our finding may also contribute to the development of an alternative phytotherapeutic anti-MRSA agent.     

Typification of <Emphasis Type="Italic">Metrosideros regelii</Emphasis> (<Emphasis Type="Italic">Myrtaceae</Emphasis>) and consideration of its generic position

Summary  The type specimen of Metrosideros regelii is discussed. It contains a mixture of two species, representing different genera, and a lectotype is chosen. The generic position of the species is considered in the light of morphology and recent molecular evidence and the new combination, Mearnsia regelii, made.     

The Madagascan genus <Emphasis Type="Italic">Vaughania</Emphasis> is reduced to synonymy under <Emphasis Type="Italic">Indigofera</Emphasis> (<Emphasis Type="Italic">Leguminosae-Papilionoideae-Indigofereae</Emphasis>)

Summary  Eleven species comprising the Madagascan genus Vaughania are subsumed within the large pantropical genus Indigofera. Six new combinations are made; the remaining species were originally described in Indigofera.     

<Emphasis Type="Italic">Phuphanochloa,</Emphasis> a new bamboo genus (<Emphasis Type="Italic">Poaceae</Emphasis>: <Emphasis Type="Italic">Bambusoideae</Emphasis>) from Thailand

Summary  A new monotypic bamboo genus Phuphanochloa (Poaceae: Bambusoideae) from north-eastern Thailand is described, together with a new species, P. speciosa.