铁皮石斛内生真菌的分离及其挥发性成分分析

铁皮石斛(Dendrobium officinale)是我国重要的濒危中药材,其药用价值和经济价值很高。以铁皮石斛为研究对象,采用组织块法,从铁皮石斛根、茎和叶中分离获得22株内生真菌。采用固相微萃取固定吸附(SPME),结合气相质谱(GCMS)解吸附分析技术对其中具有产香特性的3株内生真菌KLBMPD001、KLBMPD004和LBMPD009的挥发性成分进行分析。结果显示,这3株内生真菌均含有较高比例的棕榈酸,分别为37.94%、24.15%和48.55%,其中菌株KLBMPD001和KLBMPD009含有一定比例的硬脂酸,分别为12.64%和37.37%,只有菌株KLBMPD004含有8.74%的酞酸二丁酯。     

产香真菌JXJ 01的初步鉴定及挥发性香气成分分析

产香微生物在天然香料生产中具有重要意义。本文根据形态学、生理学、ITS基因序列等特征,对产香真菌JXJ 01进行了初步鉴定;利用同时蒸馏萃取技术提取挥发性成分,利用气相色谱-质谱(GC-MS)联用技术分析其组成。结果表明,菌株JXJ 01分泌纤维素酶和木质素酶,在PDA培养基上菌丝发达,乳白色,有隔,培养30 d后未见孢子产生,在农业废弃物固体培养基上能够产生成簇片状肉质子实体,该菌在ITS基因序列系统进化树上与赤褐鹅膏菌(Amanita fulva)聚在单独一支;其代谢产物显著促进小鼠生长;其挥发性成分中含有大量香气物质,主要成分为反-桂酸甲酯(15.24%)、桂酸乙酯(10.14%)、芳樟醇(6.33%)、3-甲基丁醇(3.67%)、苯甲醛(3.42%)、3-辛醇(2.16%)、2-甲基丙醇(1.76%)、2-甲基丁醇(1.42%)和苯甲酸乙酯(1.21%)。产香真菌JXJ 01在天然香料生产中具有重要的潜在应用价值。     

超临界CO2提取栀子花头香精油组成研究

本文报道了用毛细血管气相色谱、色谱-质谱计算机联用技术以及薄层色谱等方法分析了采用超临界 CO_2提取的栀子花头香精油化学成分。从分离出来的58个峰中初步鉴定出24个组分,占色谱峰总面积的93％。其中主要成分是顺-3-已烯醇(1.68),惕各酸甲酯(3.92％),苯甲酸甲酯(37.34％),芳樟醇(20.54％),香苇醇(10.33％),惕各酸顺-3-已烯酯(20.30％)等。     

矿区复合污染土壤真菌多样性及其对稀土-重金属离子的吸附特征

大量的稀土-重金属通过尾矿坝的浮尘、地表径流和渗滤液排放到周边土壤中,影响了土壤中的微生物群落结构。【目的】分析稀土和重金属复合污染土壤真菌群落结构并分离具有同时吸附稀土和重金属的菌株。【方法】本研究基于ITS基因,采用Illumina-Hiseq测序技术分析了包头稀土尾矿坝周边5份稀土-重金属污染土壤样品和距尾矿区20 km的1份相对未受污染的土壤样品的真菌群落特征,同时采用富集培养法从污染样品中筛选出金属耐性真菌,并对其进行吸附稀土-重金属的特性分析。【结果】群落结构为:在门水平,除了未分类门真菌(unclassified Fungi)外,子囊菌门(Ascomycota)真菌在所有土壤中占比较大(13.5%–90.5%);在纲水平上,除了未分类纲真菌外,粪壳菌纲(Sordariomycetes)真菌在B2 (73.1%)、B3 (28.4%)和B4 (20.8%)的丰度显著高于对照样点C (7.4%),而座囊菌纲(Dothideomycetes)在B5 (11.8%)的丰度明显高于B1 (3.5%);在属水平,除了未分类属,足孢子虫属(Podospora)是C(0.9%)和B3(23.6%)样点的优势种。曲霉属(Aspergillus)、未分类的格孢腔菌目(unclassified Pleosporales)和未分类的戴维迪科(unclassified Davidiellaceae)分别为B1 (3.0%)、B4 (10.5%)和B5(5.8%)的优势种,而蜡蚧属(Lecanicillium)真菌只在B2样点土壤存在且占优(51.6%)。Zn污染对真菌群落结构的影响大于稀土元素污染,且其浓度与优势的未分类真菌相对丰度呈负相关。从污染样品中共分离出6株真菌,它们分属于曲霉属(Aspergillus)(5株)和镰刀霉菌属(Fusarium)(1株)。所有分离菌株对镧(La~(3+))的吸附率均显著高于锌(Zn~(2+)),其中Aspergillus sp. B6-3对La~(3+)和锌Zn~(2+)的吸附率最高,分别为19.7%和3.9%。【结论】该研究为利用真菌去除稀土和重金属以优化生物吸附过程导向的环境生物修复和保护策略提供了机制基础。     

增香细菌HD-7的鉴定及香气成分分析

产香微生物的研究对天然香料的绿色生产具有深远的意义。本文从醇化中期的烟叶上分离得到一株细菌HD-7,根据形态学、生理生化以及16S rRNA基因序列等特征,对产香菌株HD-7进行了初步鉴定,并利用气相色谱-质谱(GC-MS)联用技术分析其发酵液的成分。结果表明,菌株HD-7初步被鉴定为短小芽孢杆菌(Bacillus pumilus);其GC-MS检测出的物质中含有较多的香气物质,主要的增香成分有丙酸乙酯,乙酸,乙酸丙酯及3-羟基-2-丁酮(乙偶姻)等,其含量分别占25.56%,12.68%,6.80%,4.86%。其中丙酸乙酯及3-羟基-2-丁酮等都是广泛使用的香料。产香细菌HD-7在生产香料上具有很大的研究价值。     

7种不同提取方式对香露兜挥发性成分的影响

为了解不同提取方式对香露兜挥发性成分的影响,以采自海南兴隆的香露兜成熟鲜叶为研究对象,采用100%甲醇蒸馏法、75%乙醇蒸馏法、100%乙醇蒸馏法、75%乙醇超声波辅助法、100%乙醇超声波辅助法、75%乙醇浸提法和100%乙醇浸提法7种不同方式进行提取,利用气相色谱-质谱法(GC-MS)测定各提取物的挥发性成分,并结合主成分分析(PCA)和相关分析(CA)对其组成和含量差异进行比较分析。结果表明,7种不同提取方式共鉴定出52种挥发性成分,主要由酯类、醇类、酮类、烯烃类、吡咯类物质组成,100%甲醇蒸馏法未检测出关键特征香气物质2-乙酰-1-吡咯啉(2-AP),其余6种方式提取物均有检出,含量变幅为1.21～37.48μg/g;7种香露兜提取物相关性系数平均值为34.80%±7.20%,PCA分析将7种提取方式分为3组:75%、100%乙醇超声波辅助提取法和75%、100%乙醇浸提法主要挥发性成分为叶绿醇、角鲨烯、3-羟基-2-丁酮、棕榈酸乙酯、羟基丙酮、3-甲基-2-(5H)-呋喃酮和2-AP,75%和100%乙醇蒸馏提取法主要挥发性成分为硬脂酸甲酯、2-AP、(E)-7-四癸醇和棕榈酸甲酯,100%甲醇蒸馏提取法主要挥发性成分为(Z)-十六烯酸甲酯、苯乙烯、十四酸甲酯、十五碳酸甲酯。由此说明,香露兜7种不同方式提取物3个组间挥发性成分的组成和含量存在差异,这为香露兜产品精深加工提供了理论依据。     

银杏内生真菌Aspergillus oryzae YX-5抗肿瘤活性物质的分离与鉴定

【背景】植物内生真菌是天然活性物质的重要来源。【目的】对一株具有抗肿瘤活性的银杏内生真菌米曲霉Aspergillus oryzae YX-5进行活性物质的分离与鉴定。【方法】将该菌株发酵培养后,发酵液经乙酸乙酯萃取,采用减压柱层析、葡聚糖凝胶柱层析和高效液相色谱分析,从其代谢产物中分离活性化合物,在分离过程中以MTT法跟踪检测分离到的各组分及纯化合物的抗肿瘤活性。【结果】从菌株YX-5的发酵产物中分离纯化得到4个化合物。经核磁共振和高分辨质谱分析,将其分别鉴定为羟基曲霉酸(1)、环(4-羟脯氨酸-苯丙氨酸)(2)、环(亮氨酸-苯丙氨酸)(3)和环(丙氨酸-苯丙氨酸)(4)。其中羟基曲霉酸对人宫颈癌HeLa细胞具有显著的细胞毒活性,其IC_(50)为1.07μg/mL。【结论】报道羟基曲霉酸在抗肿瘤方面的活性,表明米曲霉及羟基曲霉酸在抗肿瘤天然产物开发中具有一定的应用潜力。     

香果树可培养内生真菌的群落结构及功能活性菌株的筛选

为进一步保护和利用香果树这一濒危植物, 以香果树为材料, 运用传统组织分离与分子生物学方法相结合, 对4个居群地(庐山、井冈山、三清山、铜鼓)的香果树的内生真菌物种多样性、群落组成以及生态分布规律进行研究, 并对庐山香果树不同季节内生真菌进行对比分析。结果显示: 从香果树1980个组织块中分离出757株内生真菌, 其中产孢菌株240株, 占总数31.70%, 不产孢菌株517株, 占总数68.30%。根据形态学特征和分子鉴定结果, 757菌株隶属于Arthopyrenia、Colletotrichum、Phomopsis、Penicillium等40个分类单元。在属级水平, 以Arthopyrenia(19.42%)、Colletotrichum(15.32%)和Diaporthe(9.64%)为优势菌群; 根据分离频率, 不同居群地香果树内生真菌存在差异, 分离频率顺序为: 三清山(31.18%)>井冈山(30.32%)>铜鼓(24.52%)>庐山(13.98%); 根据相似性系数, 4个居群地香果树内生真菌相似性系数在0.29-0.52之间。同时研究发现不同季节香果树不同组织部位内生真菌在数量、种群分布以及优势种群等方面都存在较大差异, 其分离频率顺序为: 叶(50.99%)> 根(25.63%)>茎(23.38%), 冬季(41.74%)>秋季(40.06%)>夏季(18.21%)。形成内生真菌分布差异性可能与不同地理位置、气候因素、土壤理化性质和宿主植物组织的生理状况等密切相关。同时, 对分离获得757株香果树内生真菌菌株进行溶磷、解钾、分泌IAA的功能活性筛选, 获得82株具溶磷效果, 36株具解钾活性, 13株具分泌IAA活性的菌株, 9株既有溶磷又有解钾活性, 为进一步探索香果树植物内生真菌对宿主植物促生效应提供依据。     

毛脉酸模内生真菌蒽醌类次生代谢产物的筛选及含量分析

本文通过对毛脉酸模内生真菌的发酵培养得到其次生代谢产物,采用HPLC法对内生真菌中蒽醌类成分进行筛选。以大黄素、大黄酸、大黄酚、大黄素甲醚、芦荟大黄素五种蒽醌类成分为参照,筛选出3株真菌含大黄素、3株真菌含大黄酸、5株真菌含芦荟大黄素,其中含量最高为683μg/g、最低为8μg/g。将各菌株所含成分与各菌株分离部位的相应成分进行比较,相对宿主植物而言各菌株均有较高的含量。本实验分析方法准确、快捷,适用于毛脉酸模内生真菌的代谢产物研究。     

一个产香大型真菌鉴定及其挥发性成分分析

【目的】开发优质的产香大型真菌资源,丰富挥发性香味成分的获取途径。【方法】本文通过传统形态分类学和分子生物学相结合的方法对采自泰国北部的野生产香大型真菌及其菌株进行鉴定。利用液体发酵、HP20大孔树脂固相萃取和气相色谱-质谱联用(GC-MS)等方法分析发酵液中的挥发性物质。同时筛选了对该真菌液体培养的最佳碳源、氮源及无机盐离子条件。【结果】该真菌经鉴定为茉莉小皮伞Marasmiusjasminodorus,分析发现其主要香味组分及对应的峰面积百分比分别为芳樟醇(33.11%)、5-羟甲基糠醛(4.64%)、4-甲基-5-(β羟乙基)噻唑(4.55%)、甲基麦芽酚(4.49%)、糠醇(4.46%)、桃醛(2.20%)、羟基丙酮(2.18%)等。同时该菌的最优培养液配方中最佳碳源、氮源及无机盐离子为麦芽糖、酵母粉和KH_2PO_4。【结论】本研究表明该大型真菌能够产生多种在现有工业生产中广泛应用的挥发性香味成分,如芳樟醇等,所以其在天然香精香料生产中具有较好的潜在应用前景。     

Thermophily in the Geobacteraceae: Geothermobacter ehrlichii gen. nov., sp. nov., a novel thermophilic member of the Geobacteraceae from the "Bag City" hydrothermal vent

Little is known about the microbiology of the "Bag City" hydrothermal vent, which is part of a new eruption site on the Juan de Fuca Ridge and which is notable for its accumulation of polysaccharide on the sediment surface. A pure culture, designated strain SS015, was recovered from a vent fluid sample from the Bag City site through serial dilution in liquid medium with malate as the electron donor and Fe(III) oxide as the electron acceptor and then isolation of single colonies on solid Fe(III) oxide medium. The cells were gram-negative rods, about 0.5 micro m by 1.2 to 1.5 micro m, and motile and contained c-type cytochromes. Analysis of the 16S ribosomal DNA (rDNA) sequence of strain SS015 placed it in the family Geobacteraceae in the delta subclass of the Proteobacteria. Unlike previously described members of the Geobacteraceae, which are mesophiles, strain SS015 was a thermophile and grew at temperatures of between 35 and 65 degrees C, with an optimum temperature of 55 degrees C. Like many previously described members of the Geobacteraceae, strain SS015 grew with organic acids as the electron donors and Fe(III) or nitrate as the electron acceptor, with nitrate being reduced to ammonia. Strain SS015 was unique among the Geobacteraceae in its ability to use sugars, starch, or amino acids as electron donors for Fe(III) reduction. Under stress conditions, strain SS015 produced copious quantities of extracellular polysaccharide, providing a model for the microbial production of the polysaccharide accumulation at the Bag City site. The 16S rDNA sequence of strain SS015 was less than 94% similar to the sequences of previously described members of the Geobacteraceae; this fact, coupled with its unique physiological properties, suggests that strain SS015 represents a new genus in the family Geobacteraceae. The name Geothermobacter ehrlichii gen. nov., sp. nov., is proposed (ATCC BAA-635 and DSM 15274). Although strains of Geobacteraceae are known to be the predominant Fe(III)-reducing microorganisms in a variety of Fe(III)-reducing environments at moderate temperatures, strain SS015 represents the first described thermophilic member of the Geobacteraceae and thus extends the known environmental range of this family to hydrothermal environments.     

Effect of increased yeast alcohol acetyltransferase activity on flavor profiles of wine and distillates

The distinctive flavor of wine, brandy, and other grape-derived alcoholic beverages is affected by many compounds, including esters produced during alcoholic fermentation. The characteristic fruity odors of the fermentation bouquet are primarily due to a mixture of hexyl acetate, ethyl caproate (apple-like aroma), iso-amyl acetate (banana-like aroma), ethyl caprylate (apple-like aroma), and 2-phenylethyl acetate (fruity, flowery flavor with a honey note). The objective of this study was to investigate the feasibility of improving the aroma of wine and distillates by overexpressing one of the endogenous yeast genes that controls acetate ester production during fermentation. The synthesis of acetate esters by the wine yeast Saccharomyces cerevisiae during fermentation is ascribed to at least three acetyltransferase activities, namely, alcohol acetyltransferase (AAT), ethanol acetyltransferase, and iso-amyl AAT. To investigate the effect of increased AAT activity on the sensory quality of Chenin blanc wines and distillates from Colombar base wines, we have overexpressed the alcohol acetyltransferase gene (ATF1) of S. cerevisiae. The ATF1 gene, located on chromosome XV, was cloned from a widely used commercial wine yeast strain of S. cerevisiae, VIN13, and placed under the control of the constitutive yeast phosphoglycerate kinase gene (PGK1) promoter and terminator. Chromoblot analysis confirmed the integration of the modified copy of ATF1 into the genome of three commercial wine yeast strains (VIN7, VIN13, and WE228). Northern blot analysis indicated constitutive expression of ATF1 at high levels in these yeast transformants. The levels of ethyl acetate, iso-amyl acetate, and 2-phenylethyl acetate increased 3- to 10-fold, 3.8- to 12-fold, and 2- to 10-fold, respectively, depending on the fermentation temperature, cultivar, and yeast strain used. The concentrations of ethyl caprate, ethyl caprylate, and hexyl acetate only showed minor changes, whereas the acetic acid concentration decreased by more than half. These changes in the wine and distillate composition had a pronounced effect on the solvent or chemical aroma (associated with ethyl acetate and iso-amyl acetate) and the herbaceous and heads-associated aromas of the final distillate and the solvent or chemical and fruity or flowery characters of the Chenin blanc wines. This study establishes the concept that the overexpression of acetyltransferase genes such as ATF1 could profoundly affect the flavor profiles of wines and distillates deficient in aroma, thereby paving the way for the production of products maintaining a fruitier character for longer periods after bottling.     

Aggregation pheromones in five taxa of the Drosophila virilis species group

ABSTRACT. Aggregation pheromones have been demonstrated in the closely related taxa: Drosophila americana americana Spencer, D. a. texana Patterson, D. novamexicana Patterson, and D. lummei Hackman. These pheromones function much as has been reported previously for D. virilis Sturtevant. The compounds are produced by sexually mature males, but both sexes respond in a wind-tunnel olfactometer. In all species except D. lummei , a 21-carbon alkene is an important pheromone component. In D. virilis the hydrocarbon is (Z)-10-heneicosene (Z10–21), but in D. a. americana, D. a. texana and D. novamexicana it is (Z)-9-heneicosene (Z9-21). All these taxa respond best to the heneicosene which they produce. D. lummei possesses no heneicosenes but, curiously, responds well to both Z9-21 and Z10-21. All species possess five male-specific esters which were previously discovered in D. virilis : methyl tiglate, ethyl tiglate, isopropyl tiglate, methyl hexanoate and ethyl hexanoate. Ethyl tiglate is the most abundant in each case. Responses to the esters vary among the taxa, ranging from highly significant in D. lummei , particularly to ethyl tiglate, to not demonstrable in D. a. americana. Variability in ester response has also been demonstrated between two strains of D. virilis. In all cases the crude male-derived pheromone is synergistic with an extract of fermented willow bark, on which oviposition is said to occur.     

Effect of Increased Yeast Alcohol Acetyltransferase Activity on Flavor Profiles of Wine and Distillates

The distinctive flavor of wine, brandy, and other grape-derived alcoholic beverages is affected by many compounds, including esters produced during alcoholic fermentation. The characteristic fruity odors of the fermentation bouquet are primarily due to a mixture of hexyl acetate, ethyl caproate (apple-like aroma), iso-amyl acetate (banana-like aroma), ethyl caprylate (apple-like aroma), and 2-phenylethyl acetate (fruity, flowery flavor with a honey note). The objective of this study was to investigate the feasibility of improving the aroma of wine and distillates by overexpressing one of the endogenous yeast genes that controls acetate ester production during fermentation. The synthesis of acetate esters by the wine yeast Saccharomyces cerevisiae during fermentation is ascribed to at least three acetyltransferase activities, namely, alcohol acetyltransferase (AAT), ethanol acetyltransferase, and iso-amyl AAT. To investigate the effect of increased AAT activity on the sensory quality of Chenin blanc wines and distillates from Colombar base wines, we have overexpressed the alcohol acetyltransferase gene (ATF1) of S. cerevisiae. The ATF1 gene, located on chromosome XV, was cloned from a widely used commercial wine yeast strain of S. cerevisiae, VIN13, and placed under the control of the constitutive yeast phosphoglycerate kinase gene (PGK1) promoter and terminator. Chromoblot analysis confirmed the integration of the modified copy of ATF1 into the genome of three commercial wine yeast strains (VIN7, VIN13, and WE228). Northern blot analysis indicated constitutive expression of ATF1 at high levels in these yeast transformants. The levels of ethyl acetate, iso-amyl acetate, and 2-phenylethyl acetate increased 3- to 10-fold, 3.8- to 12-fold, and 2- to 10-fold, respectively, depending on the fermentation temperature, cultivar, and yeast strain used. The concentrations of ethyl caprate, ethyl caprylate, and hexyl acetate only showed minor changes, whereas the acetic acid concentration decreased by more than half. These changes in the wine and distillate composition had a pronounced effect on the solvent or chemical aroma (associated with ethyl acetate and iso-amyl acetate) and the herbaceous and heads-associated aromas of the final distillate and the solvent or chemical and fruity or flowery characters of the Chenin blanc wines. This study establishes the concept that the overexpression of acetyltransferase genes such as ATF1 could profoundly affect the flavor profiles of wines and distillates deficient in aroma, thereby paving the way for the production of products maintaining a fruitier character for longer periods after bottling.     

高产洛蒙真菌素洛蒙德链霉菌高通量筛选方法的建立与复合育种

[背景]洛蒙德链霉菌S015能生物合成具有广谱抗菌活性的吩嗪类化合物洛蒙真菌素。[目的]因S015菌株的洛蒙真菌素产量较低,将S015菌株经复合诱变育种和基因工程改造,提高洛蒙真菌素产量。[方法]建立洛蒙真菌素产生菌的高通量筛选方法,对出发菌株S0 15进行常压室温等离子体(atmospheric and room temperature plasma,ARTP)技术和紫外复合诱变,筛选得到高产菌株;并在高产菌株上敲除洛蒙真菌素的前体分支酸竟争途径中的关键基因trpE1、trpE2,再过表达全局调控基因afsR。[结果]利用洛蒙真菌素在紫外波长375 nm处的特征吸收峰,以及洛蒙真菌素浓度和375 nm处吸光度值的正相关关系,建立了基于24孔深孔板发酵和酶标仪快速检测的高通量筛选方法。经过6轮ARTP和紫外复合诱变及高通量筛选,从4 320株突变株中筛选得到遗传稳定的高产菌株M6,其洛蒙真菌素的产量为61.33 mg/L,是S015菌株的7.35倍;M6菌株的分支途径基因trpE1、trpE2双敲株的洛蒙真菌素产量为81.89 mg/L,是S015菌株的9.82倍;在该基因工程菌株中过表达全局调控基因afsR,产量为109.53 mg/L,是S015菌株的13.13倍。[结论]建立的高通量筛选方法可以有效筛选高产洛蒙真菌素的突变株,并且操作简单快速。通过ARTP和紫外复合诱变,结合高产株M6的基因工程改造,能进一步提升洛蒙真菌素的产量。     

Pollination of Specklinia by nectar-feeding Drosophila: the first reported case of a deceptive syndrome employing aggregation pheromones in Orchidaceae

Background and Aims The first documented observation of pollination in Pleurothallidinae was that of Endrés, who noticed that the ‘viscid sepals’ of Specklinia endotrachys were visited by a ‘small fly’. Chase would later identify the visiting flies as being members of the genus Drosophila. This study documents and describes how species of the S. endotrachys complex are pollinated by different Drosophila species.Methods Specimens of Specklinia and Drosophila were collected in the field in Costa Rica and preserved in the JBL and L herbaria. Flies were photographed, filmed and observed for several days during a 2-year period and were identified by a combination of non-invasive DNA barcoding and anatomical surveys. Tissue samples of the sepals, petals and labellum of Specklinia species were observed and documented by SEM, LM and TEM. Electroantennogram experiments were carried out on Drosophila hydei using the known aggregation pheromones ethyl tiglate, methyl tiglate and isopropyl tiglate. Floral compounds were analysed by gas chromatography–mass spectometry using those same pheromones as standards.Key Results Flowers of S. endotrachys, S. pfavii, S. remotiflora and S. spectabilis are visited and pollinated by several different but closely related Drosophila species. The flies are arrested by aggregation pheromones, including ethyl tiglate, methyl tiglate and isopropyl tiglate, released by the flowers, and to which at least D. hydei is very sensitive. Visible nectar drops on the adaxial surface of sepals are secreted by nectar-secreting stomata, encouraging male and female Drosophila to linger on the flowers for several hours at a time. The flies frequently show courtship behaviour, occasionally copulating. Several different Drosophila species can be found on a single Specklinia species.Conclusions Species of the S. endotrachys group share a similar pollination syndrome. There seem to be no species-specific relationships between the orchids and the flies. It is not expected that Specklinia species will hybridize naturally as their populations do not overlap geographically. The combination of pheromone attraction and nectar feeding is likely to be a generalized pollination syndrome in Pleurothallidinae.     

一株耐受低pH、高浓度硒菌株的筛选鉴定及两阶段pH调控高效除硒的研究

通过酸性含硒平板和摇瓶筛选出一株对低pH、高浓度硒有很好耐受性的菌株Y1,通过菌落形态特征分析和26S rDNA测序,鉴定该菌株为Pichia kudriavzevii,多抗性实验结果显示该菌是一株多重耐受性毕赤酵母。通过摇瓶实验研究了温度、接种量、摇床转速、pH对菌株除硒性能的影响,结果显示当温度为25℃,接种量为12%(v/v),摇床转速为250 r/min,pH为3.0时,菌株对硒的去除率最高为58.3%。基于不同pH发酵过程中菌体生物量及富硒量的不同表现:pH 3.0时生物量最高,pH 5.0时富硒量最高,提出两阶段pH调控策略:发酵0 h~14 h将pH控制在3.0,14 h~28 h将pH控制在5.0,最终除硒率可达78.6%,分别比pH恒定在3.0及5.0条件下提高了15.4%和21.7%。     

湖北栀子花挥发油的GC/MS分析

利用水蒸气蒸馏法从湖北栀子花鲜花中提取栀花挥发油。通过ＤＢ－５弹性石英毛细管柱ＧＣ／ＭＳ分析所得栀子花挥发油,共鉴定了４０个化合物并测定了其相对含量。湖北子发挥发油的主要成分为芳樟醇（１７．９２％）,茉莉内酯（９．１１％）和惕各酸顺－３－己烯酯（６．５４％）。     

高产辅酶Q10结构类似物抗性突变株的选育

以土壤杆菌(Agrobacteriumsp.)TLY-4为出发菌株,采用70%致死剂量的NTG进行诱变处理,通过筛选抗辅酶Q10结构类似物维生素K3突变株,定向选育到了两株辅酶Q10高产突变株,编号为R-122和R-015,其摇瓶发酵72h时的辅酶Q10产量分别为57.3 mg/L和59.9 mg/L,较出发菌株提高了35.7%和41.6%。通过连续传代实验,表明突变株高产辅酶Q10的遗传性状稳定。实验以有机溶剂DMF和吐温-80共同增溶的方法,解决了维生素K3在培养基中易析出的问题,并确定了平板培养基中维生素K3的最小抑菌浓度为0.15 mg/mL。     

Saccharothrix yanglingensis sp. nov., an antagonistic endophytic actinomycete isolated from cucumber plant

An endophytic actinomycete strain, designated Hhs.015^T, was isolated from roots of cucumber seedlings. The endophytic isolate was identified by means of a polyphasic taxonomic approach. On the basis of 16S rRNA gene sequence similarities, strain Hhs.015^T was closely related to members of the genus Saccharothrix. DNA–DNA hybridization with the four closest relatives, Saccharothrix longispora NRRL B-16116^T, Saccharothrix xinjiangensis NRRL B-24321^T, Saccharothrix autraliensis CGMCC 4.1355^T and Saccharothrix espanaensis CGMCC 4.1714^T, gave similarity values of 33.8, 28.2, 44.1 and 29.5%, respectively, which indicated that strain Hhs.015^T represents a novel species of the genus Saccharothrix. This is consistent with the morphological, physiological and chemotaxonomic data. As a whole, these results suggest that strain Hhs.015^T represents a novel Saccharothrix species. The name Saccharothrix yanglingensis sp. nov. is proposed, with the type strain Hhs.015^T (=CGMCC 4.5627^T = KCTC 19722^T).