一株仙人掌植物内生真菌的分离鉴定及活性研究*

从元江仙人掌的茎中分离到一株产广谱、高活性抑菌物质的内生真菌,经测定对细菌、植物病原真菌和皮肤致病真菌共21种病原微生物有较为明显的抑制作用。形态特征表明,该菌株与曲霉属(Aspergillus)中的土生曲霉(Aspergillus terreus)的特征基本一致,18S rDNA序列分析显示本菌株与土生曲霉的同源性高于99%,但该菌株的分生孢子梗上有明显的瘤状突起,不同于模式菌株。因此认为该菌株为土生曲霉的一个变种,命名为土生曲霉云南变种(Aspergillus ter     

土生曲霉转化三七中药材的研究

从土壤真菌中筛选出直接转化中药材三七化学成分的菌株YM31966,经鉴定该菌株为土生曲霉(Aspergillus terreus).以固态转化方式,结合化学提取分离方法,通过高效液相色谱、核磁共振及质谱等波谱检测,该菌株转化三七产物由三七皂苷nR2 、RX1和人参皂苷Rg1、Rd、Rh1、Rh4构成主体成分,而原三七成分Rb1、Rc、Re和R1、R3,R6等物质被分解.结果表明,土生曲霉是一株能转化中药材三七的微生物,它具有改变原三七化学成分,形成新化合物,以及提高某些原化合物成分含量的作用.     

一种黄秋葵病原真菌的分离鉴定

报道一种在湖南地区发现的黄秋葵花蕾病原真菌。利用PDA培养基分离纯化病原菌株并依据柯赫氏法确定为病害的病原物,通过形态学鉴定和ITS序列分析鉴定病原种类。结果表明,从黄秋葵染病花蕾组织中分离纯化了一种病原真菌,通过形态观察以及ITS序列的比对分析,将该菌株鉴定为棘孢曲霉(Aspergillus aculeatus);其田间接种黄秋葵花蕾的致病率为80%。这是首次报道棘孢曲霉是黄秋葵花蕾病害的病原菌。     

一株具有杀虫活性真菌的鉴定

通过对分离的一株海绵共附生真菌F28的形态特征、生理生化特性的测定及ITS1-5.8S-ITS2序列分析,最终将其确定为米曲霉(Aspergillus oryzae)。该菌株具有生长快,易培养的特点。将该菌株进行发酵和杀虫活性物质提取分离后,通过杀卤虫(Brine Shrimp)活性测试,发现该真菌的代谢产物粗提物具有很强的杀虫活性。     

死谷芽胞杆菌B10发酵条件的研究与抗菌谱的测定

死谷芽胞杆菌B10可抑制多种食用菌病原木霉菌的生长,同时对其他多种食用菌病原真菌有拮抗作用,因此是1株很有潜力的生防菌,具有开发成生防产品的潜能。实验通过摇瓶培养,对死谷芽胞杆菌B10产生抑菌活性物质的发酵培养基和培养条件进行优化,并对其抑菌谱进行了测试。结果表明,实验产生抑菌活性物质的最佳培养基为NB液体培养基,最佳发酵条件为:菌株种龄18 h,发酵周期36 h,初始培养基pH为7.0,培养温度为30℃,摇瓶装液量为100 mL/250 mL,接种量为4%,摇床转速为170 r/min。B10发酵无菌滤液对多种食用菌病原真菌有明显抑制作用,其中对哈茨木霉T22抑制作用最强,抑菌率达90.56%。     

一株内生真菌黑曲霉的活性检测及鉴定

从飞龙斩血内分离到一株产广谱、高活性抑菌物质的内生真菌F-001,经测定对细菌、植物病原真菌和皮肤致病真菌共26种病原微生物有不同程度的抑制作用。对其进行了系统鉴定和生物学研究,形态特征表明,该菌株与曲霉属Paecilomyces Bainier中的黑曲霉Paecilomyceslilacinus的特征基本一致,ITS序列分析显示本菌株与多个黑曲霉菌株同源性都在99%,因此将菌株F-001命名为黑曲霉Paecilomyces lilacinusF-001。该研究首次从核桃树皮内分离得到黑曲霉并进行了该菌株的抑菌活性检测。     

木榄根际土壤来源的曲霉属真菌F5及其抗菌活性代谢产物

将一株分离自木榄根际土壤的菌株F5鉴定为曲霉属环绕组真菌成员,其在形态学特征和ITS序列上与Aspergillus ochraceopetaliformis极为相似。该菌株在改良葡萄糖蛋白胨酵母培养基(GPYM)中28℃下160r/min发酵7d后的产物具有明显的抑菌活性。利用色谱方法从菌株F5的发酵产物中分离鉴定到2种化合物:(R)-(-)-mellein(Ⅰ)和flavacol(Ⅱ),其中,flavacol对枯草芽孢杆菌的生长具有明显的抑制作用,最低抑菌浓度(MIC)为32mg/L,而mellein对金黄色葡萄球菌和枯草芽孢杆菌的生长均无明显的抑制活性。     

1株红海榄根际纤维素降解真菌的分离鉴定及其酶学性质

利用刚果红纤维素培养基,从海南三亚红海榄植物根际土壤中筛选得到1株纤维素降解真菌,将其命名为Z-2-4.形态学初步鉴定结果为曲霉属(Aspergillus),对其ITS、β-微管蛋白(β-tubulin)、钙调节蛋白(calmodulin)基因序列进行了扩增并测序.结果表明:该菌的ITS序列与其亲缘关系最近的Aspergillus insulicola( EF661430.1)只有94％的相似性,β-微管蛋白序列与Aspergillus insulicola( FR775320.1)的相似性为89％,钙调节蛋白序列与Aspergillus insulicola( EF661396.1)的相似性为93％,推测该菌为Aspergillus属的1个新种.对该菌株进行了酶学性质的初步研究,结果显示该菌株所产纤维素酶的最佳反应温度为40℃,最佳反应pH值为6.0,产纤维素酶活力最高出现在发酵4天时,达到2.57 U/mL.     

木聚糖酶生产菌株的筛选及产酶条件的优化

以甘蔗渣半纤维素为碳源,从垃圾场土壤中分离到6株分解半纤维素的菌株。通过固态发酵的木聚糖酶活力比较筛选到1株木聚糖酶活力较高的菌株。该菌株18S rDNA序列与曲霉（Aspergillus sp.）的同源性达97%,根据对菌株形态学分析和18S rDNA序列分析的结果,将该菌株鉴定为曲霉HQ3。HQ3的最佳产酶条件为：甘蔗渣:麸皮为7:3（W/W）,固液比为1:4（W/W）,尿素0.4 %,pH7.0,温度30℃,发酵产酶时间4 d。在最佳产酶条件下,其木聚糖酶活最高可达3421U/g干曲。     

微生物酶解法产生阿拉伯糖——菌种筛选与初步鉴定

使用半纤维素平板法从土壤分离菌中筛选到产半纤维素酶活较高的真菌。将这些菌株在含玉米芯半纤维素的培养基中发酵,鉴定发酵液中还原糖产量,从中筛选出3株产还原糖较多的菌。将其发酵产物经柱前衍生,HPLC检测,发现其中DHC菌株的发酵产物以木糖和阿拉伯糖为主,而培养基中的葡萄糖大部分被利用,可用于发酵法联产阿拉伯糖和木糖。对DHC菌株通过菌落形态、孢子形态以及ITS区基因序列测序分析,初步确定该菌为亮白曲霉(Aspergillus candidus)。对于亮白曲霉产生的半纤维素酶国内外尚较少研究报导,可为开发利用新的微生物资源奠定基础。     

Isolation of an Aspergillus terreus mutant impaired in arginine biosynthesis and its complementation with the argB gene from Aspergillus nidulans

Using filtration enrichment techniques, an Aspergillus terreus arginine auxotrophic strain which contains a mutation that abolishes ornithine transcarbamylase (OTCase) activity has been isolated. This mutant has been genetically transformed with the cloned Aspergillus nidulans OTCase gene. Prototrophic transformants arose at a frequency of about 50 transformants per microgram of plasmid DNA. Southern blot analysis of DNA from the transformants showed that the transforming DNA was ectopically integrated at different locations in the A. terreus genome, often in multiple tandem copies. The transformants were phenotypically stable for several mitotic divisions and retained their capacity to produce extracellular enzymes.     

Cellulolytic activity of moulds. I. Characteristics of the cellulases complex and xylanase of the strain Aspergillus terreus F-413

Among 79 strains of moulds belonging to 17 different species, the strain Aspergillus terreus F-413 which showed the highest cellulolytic activity was isolated for further studies. Some properties of the complex of cellulases formed by this strain as well as the dynamics of their synthesis under optimal submerged culture conditions were characterized.     

Removal of heavy metals by an Aspergillus terreus strain immobilized in a polyurethane matrix

AIMS: The aim was to investigate the biosorption of chromium, nickel and iron from metallurgical effluents, produced by a steel foundry, using a strain of Aspergillus terreus immobilized in polyurethane foam. METHODS AND RESULTS: A. terreus UFMG-F01 was immobilized in polyurethane foam and subjected to biosorption tests with metallurgical effluents. Maximal metal uptake values of 164.5 mg g(-1) iron, 96.5 mg g(-1) chromium and 19.6 mg g(-1) nickel were attained in a culture medium containing 100% of effluent stream supplemented with 1% of glucose, after 6 d of incubation. CONCLUSIONS: Microbial populations in metal-polluted environments include fungi that have adapted to otherwise toxic concentrations of heavy metals and have become metal resistant. In this work, a strain of A. terreus was successfully used as a metal biosorbent for the treatment of metallurgical effluents. SIGNIFICANCE AND IMPACT OF THE STUDY: A. terreus UFMG-F01 was shown to have good biosorption properties with respect to heavy metals. The low cost and simplicity of this technique make its use ideal for the treatment of effluents from steel foundries.     

离子束注入对衣康酸生产菌种的改良

用10keV、剂量5.2×10~(14)～5.2×10~(15)ions/cm~2的氮离子注入衣康酸生产菌株土曲霉A9003,在2％LiCl抗性平板筛选到一株能在39℃发酵的衣康酸高产菌株。该菌株在30L发酵罐发酵产酸7.5％,转化率60.1％,发酵周期50h。     

Biodegradation of lignocellulosic waste by Aspergillus terreus

Biodegradation of lignocellulosic waste by Aspergillus terreus is reported for the first time. This isolate produced 250 CMCase (carboxymethyl cellulase or endoglucanase) U.ml(-1) and biodegraded hay and straw during 3 days and the biomass production on straw was 5g.L(-1) dry weight from 0.25 cm2 inoculated mycellium. This strain secreted endocellulases and exocellulases in the culture medium, but some of the enzymes produced, remained cell membrane bound. Cell bound enzymes were released by various treatments. The highest amount of endoglucanase and exoglucanase was released when the cells were treated with sonication. Aspergillus terreus was added to two tanks containing sugar wastewater and pulp manufacturing waste, as a seed for COD removal. This fungus reduced the COD by 40-80 percent, also, ammonia was reduced from 14.5 mM to 5.6 mM in sugar beet wastewater. The effects of crude enzyme of this fungus for COD removal was studied.     

Conversion of cyclic nonaketides to lovastatin and compactin by a lovC deficient mutant of Aspergillus terreus.

Investigation of the post-PKS biosynthetic steps to the cholesterol-lowering agent lovastatin (1) using an Aspergillus terreus strain with a disrupted lovC gene, which is essential for formation of 4a,5-dihydromonacolin L (3), shows that 7 and 3 are precursors to 1, and demonstrates that lovastatin diketide synthase (lovF protein) does not require lovC.     

Characterization of glucoannylaserom Asperigillus terreus 4

A strain of Aspergillus terreus 4 was found to show extracellular amylolytic activity and the amylase was identified as glucoamylase enzyme. The optimum temperature for the enzyme activity was 60% and it was stable at this temperature for 1 h. The enzyme was optimally active at pH 5.0 and stable between pH 3.0-8.0. Km values of glucoamylase for soluble starch, amylose and amylopectin were 5.9 mg/ml, 4.8 mg/ml and 2.6 mg/ml respectively.     

RNAi沉默lovF基因实现土曲霉一步法发酵生产辛伐他汀

辛伐他汀是重要的降胆固醇处方药物。莫那可林J是辛伐他汀合成过程的关键中间体,也是洛伐他汀生物合成的中间产物。为获得莫那可林J并通过一步法发酵生成辛伐他汀,构建了洛伐他汀生物合成关键基因lov F基因的RNAi载体p MHJ137,通过农杆菌介导的方法转化土曲霉F001,筛选整合到染色体的阳性菌,并在阳性菌株MJ1-24的发酵过程中加入了DMB-S-MMP验证其直接合成辛伐他汀的效率。结果显示MJ1-24不再产生洛伐他汀,产物中仅有莫那可林J累积。如果在发酵过程中加入前体物质,可得到产物辛伐他汀。综上,RNAi技术能够有效实现土曲霉基因沉默。此项技术推进了一步法发酵生产辛伐他汀的工艺开发。     

两性霉素B抗真菌作用机制与病原性土曲霉对其耐药机制的研究进展

两性霉素B(amphotericin B, AMB)是经典的多烯类抗真菌药物,对病原真菌具有广谱抗菌活性,且不易产生耐药性。土曲霉是临床上常见的病原性曲霉,因其对AMB天然耐药而受到关注。现阶段,AMB的抗真菌作用机制有待进一步阐明,且真菌对AMB的耐药机制研究亦不充分。本文就AMB在土曲霉中诱导内源性活性氧(reactive oxygen species, ROS)产生的抗真菌作用机制进行介绍,并重点讨论应激适应通路(热休克蛋白90、热休克蛋白70和钙调磷酸酶)、ROS清除酶以及线粒体功能在土曲霉对AMB耐药中的作用。这些新发现对了解AMB在其他病原性曲霉中的作用机制和耐药机制都具有重要的临床意义。