云南若干地区土壤放线菌区系及资源考察 X.滇东南地区

从云南省文山、红河等地采集不同植被、不同海拔高度的土壤样品,用不同方法分离高温、中温放线菌,按国内外通用的方法进行鉴定。滇东南地区的土壤放线菌种类丰富,分离到了13个菌属,稀有放线菌的数量所占比例较高。原始森林中的放线菌种属最丰富。本文对该地区放线菌的生态分布进行了探讨。     

The influence of fertilizers on root rot of field peas caused by Fusarium oxysporum,Pythium vexans and Rhizoctonia solani inoculated singly or in combination

A Frankia strain ISU 0224887 was isolated from spore negative root nodules of Gymnostoma sumatranum and was grown in pure culture. It was infective and effective for Gymnostoma species but failed to nodulate Allocasuarina and Casuarina seedlings. Light and scanning electron microscopy of it in nitrogen free medium revealed a filamentous mat of septate and branched hyphae bearing sporangia and vesicles capable of fixing nitrogen. The strain also produced an orange pigment after 2 weeks culture. The strain utilized only TWEEN 80 and propionate as sole carbon sources. The different antibiotics used showed varying effects on its growth.     

Nitrogen-fixing root nodules inDatisca Cannabina L.

Summary The occurrence of root nodules inDatisca cannabina is reported. The nodules are typically of the Alnus type, forming dichotomously-branched coralloid clusters. The enlarged cortical cells contain vesicle clusters of the endophyte. The nodules reduced acetylene to ethylene at a rate of 5.5 moles ethylene per g fresh wt of nodules per hour.     

An actinomycete producing L-3,4-dihydroxyphenylalanine from L-tyrosine

An actinomycete was isolated during a soil screening programme to obtain L-3,4-dihydroxyphenylalanine producers. A mutant of this organism was isolated by chemical mutagenesis and it accumulated 1 g/litre L-dihydroxyphenylalanine when grown on L-tyrosine. Resting cells converted 30% of tyrosine in the reaction mixture. The use of resting cells for dihydroxyphenylalanine production is advantageous as it eliminates interfering substances which accumulate during fermentation.     

云南若干地区土壤放线菌区系及资源考察——Ⅸ.滇西和滇东北地区

云南省西部属横断山脉的南端,该地区内温泉分布十分广泛。云南省的东北部则属中山山原区,是乌蒙山系向北伸延的末端。这两个地区的地貌、气候、植被区系均有很大差异。从上述两个样区的原始森林、次生林、荒地、旱地、蔬菜地、水田采集200份土样,用多种培养基分离和鉴定其中的放线菌,并从中筛选出有用的菌株,研究了上述两地区的土壤放线菌的区系组成及异同。     

Identification of novel membrane-bound phospholipase D from Streptoverticillium cinnamoneum, possessing only hydrolytic activity

A membrane-bound phospholipase D (PLD) has been identified and isolated in a soluble form from an actinomycete, Streptoverticillium cinnamoneum. The enzyme has a monomeric structure with a molecular size of about 37 kDa, being the smallest among the enzymes so far reported. The enzyme catalyzes the hydrolysis of phosphatidylethanolamine and phosphatidylserine as preferred substrates, but not the transphosphatidylation reaction of their phospholipid groups to ethanol. Together with the absence of immunochemical cross-reactivity, these enzymatic properties demonstrate that the membrane-bound enzyme is distinct from the extracellular enzyme recently characterized and cloned from the same bacterial strain [C. Ogino et al., J. Biochem. 125 (1999) 263–269] and is therefore regarded as a novel prokaryotic PLD.     

西藏地区土壤放线菌种群多样性及拮抗活性研究

从西藏不同海拔、不同气候条件的5个地区采集的10份土样中,使用选择分离培养基、ISP 2（Yeast extract_malt extract agar）和高氏一号培养基,通过分散差速离心法（Dispersion and differential centrifugation,DDC）分离得到放线菌156株。根据形态和培养特征将其归入32个类群,并从中选出65个代表菌株进行全细胞壁氨基酸组分分析,结果表明：９株菌为非链霉菌胞壁类型,其余为链霉菌胞壁类型。16S rDNA扩增片段长度多态性（ARDRA）分析得到不同带型,对其序列分析结果表明：分离菌株分属链霉菌属（Streptomyces）和5个稀有放线菌属。同时测试了代表菌株抗耐药细菌和真菌的活性,其中38.5%的菌株具有拮抗活性。     

一株降解纤维素放线菌的产纤维素酶基因克隆与表达

【背景】纤维素在自然界中储量丰富,但天然纤维素的难降解性成为广泛应用纤维素资源的壁垒,近年来利用微生物来降解纤维素成为热点研究。【目的】筛选分离得到一株具有降解纤维素功能的放线菌菌株Lb1,通过全基因组测序确定其产纤维素酶关键基因5676,对基因5676进行克隆转化,使其在大肠杆菌中进行表达。【方法】通过基因工程技术将产纤维素基因连接到表达质粒上并导入表达菌株,对其降解纤维素生成葡萄糖的能力进行探究。【结果】将Lb1菌株的16S rRNA基因进行比对,确定菌株Lb1属于链霉菌属,命名为Streptomyces sp. Lb1。成功构建出纤维素酶表达载体,并且导入表达菌株大肠杆菌BL21(DE3),重组菌株的产纤维素酶能力大于空载菌株。【结论】通过基因工程技术成功克隆出产纤维素酶基因,从而表达纤维素酶,为今后利用微生物降解纤维素的大规模应用提供参考。     

辐射污染区土壤中放线菌的分离及多样性

从辐射污染区采集42份土样, 分别采用6种分离培养基进行放线菌的分离, 共获得152株放线菌。经形态、核糖体DNA扩增片段限制性内切酶(Amplifed ribosomal DNA restriction analysis, ARDRA)分析比较, 选取其中的60株进行16S rRNA基因测序。通过序列比对、聚类分析, 60株菌分布在放线菌纲中的12个属, 链霉菌属占大多数, 有大量稀有放线菌, 这表明辐射污染区具有较丰富的放线菌属种多样性。     

盐碱环境放线菌多样性研究

放线菌因产生多种多样的生物活性物质而受到重视。但极端环境放线菌的研究甚少。采用DGGE、纯培养法,重点研究了新疆、青海及埃及的重盐碱环境的放线菌分布情况,种类组成,生物学特性。发现了1个新科,8个新属及30多个新种。从嗜(耐)盐碱放线菌筛选到许多带有PKS基因的菌株。认为极端环境放线菌是生物活性物质的重要来源;改进分离程序,分离未知放线菌,是放线菌多样性研究及开发利用的前提之一;并对极端环境放线菌研究作了论述。