2株杀萝卜蚜放线菌的筛选与鉴定

[目的]2株从土壤中分离的对萝卜蚜虫有活性放线菌及其分类鉴定。[方法]用平板稀释法对土样进行分离,以萝卜蚜为供试靶标昆虫,采用浸叶法进行杀虫活性测定,根据形态特征、培养特征及生理生化性状对活性菌株进行分类鉴定。[结果]菌株DY3和LY1发酵上清液48 h对萝卜蚜的校正死亡率分别为76.99%和73.45%,菌株DY3稀释16倍菌株LY1稀释4倍对萝卜蚜的校正死亡率分别为68.11%和52.59%。[结论]菌株DY3和LY1发酵液对萝卜蚜具有杀虫活性,均鉴定为链霉菌属(Streptomyces)。     

链霉菌菌株4903抑菌除草活性的研究

从士样中分离筛选的链霉菌4903菌株的代谢产物同时具有抑菌、除草活性。链霉菌4903对荔枝炭疽病菌（Glomerella cingulata）和荔枝霜疫霉菌（Peronophythora litchii）的抑菌圈透明,抑菌圈直径达到和超过25mm。除草活性生测结果表明：在固体培养条件下,链霉菌4903菌株对小麦（Triticum aestivum）和油菜（Brassica campestris）有强烈的抑制作用,链霉菌4903菌株对小麦苗的抑制率为94%.对油菜根和苗的抑制率分别为97％和83％。     

抗生素杀螨剂浏阳霉素开发研究

我所1979年开始进行杀虫素研究,经大量分土和筛选,从湖南浏阳地区土壤中分离到编号为S-12菌株,经鉴定命名为灰色链霉菌浏阳变种(S.griseius Var.liuyangensis),在其发酵培养液的滤饼中分离出具有杀螨活性物质,被命名为浏阳霉素。     

Dicloromezotiaz的合成与生物活性

Dicloromezotiaz是杜邦公司开发的新型介离子类杀虫剂。以2-氨基-3-甲基吡啶和3,5-二氯苯乙酸为起始原料合成了dicloromezotiaz,目标化合物结构经1~H NMR、MS确证。杀虫活性测试结果表明:dicloromezotiaz对小菜蛾、黏虫以及桃蚜均具有优异的杀虫活性。在2.5 mg/L质量浓度下其对小菜蛾、黏虫和桃蚜的防效分别为90.2%、100%和90%。     

阿维菌素拥有“绿色”前景

阿维菌素是一类具有杀虫、杀螨、杀线虫活性的十六元大环内酯化合物,由链霉菌中的灰色链霉菌Streptomycesavermitilis发酵产生。由日本北里大学大村智等和美国默克公司首先开发成功。     

龙葵绿果对小菜蛾的杀虫活性初探

采用浸渍法,测定了龙葵绿果乙醇提取物和石油醚、氯仿、乙酸乙酯、正丁醇、水5种不同极性溶剂萃取物对小菜蛾的触杀活性.结果表明:95%乙醇提取物对小菜蛾有较高的触杀活性,而且随着提取物质量浓度的增大和处理时间的延长,小菜蛾的校正死亡率升高.质量浓度为50.00 g/L时,72 h的校正死亡率达到97.62%,LC50值4.798 g/L.5种萃取物对小菜蛾杀虫活性主要集中在石油醚和氯仿萃取部分,石油醚和氯仿萃取物72 h的校正死亡率分别为83.33%和73.33%.     

含酰脲基团的苯基吡唑类杀虫剂的合成及生物活性

[目的]为了获得具有较好杀虫活性的化合物。[方法]基于活性片段拼接和中间体衍生化法,将苯基吡唑与酰脲基团结合。[结果]合成了8个结构新颖的5-酰脲基苯基吡唑类化合物,并对其进行了杀虫活性测试,其中化合物4d在5 mg/kg下对小菜蛾的活性为100%,化合物4d、4g在0.25 mg/kg下对蚊幼虫的活性为100%。[结论]目标化合物具有较好的杀虫活性,但相对于氟虫腈活性有所降低。     

小桐子油粕提取物杀虫活性初步研究

采用盆栽喷雾接虫法、药膜法和点滴法对小桐子油粕粗提物的杀虫活性进行了初步研究。结果表明:小桐子石油醚浸膏EC和小桐子乙酸乙酯浸膏EC对小菜蛾3龄幼虫、豆蚜和甘蓝蚜虫均有一定的杀虫活性,其中小桐子乙酸乙酯浸膏EC对甘蓝蚜虫的72 h致死率达83.3%。     

农用抗生素产生菌Streptomyce SN03菌株的诱变选育

以链霉菌SN03菌株为出发菌株,采用紫外线诱变结合微波诱变的处理方法,通过对致死率、正负突变率和活性最大提高率的测定,确定了紫外线和微波诱变的最适时间,结合对诱变菌株的传代稳定性测定,获得了高效菌株UV-1-W3,其发酵液的抑菌圈直径达到33.2mm,抗菌活性比出发菌株提高了30.20%。     

放线菌BOS-009的分离、拮抗活性及鉴定

对从长白山不同海拔环境中分离筛选出可以产生抗菌活性物质的BOS-009放线菌菌株进行了研究,测定了该菌的抗菌谱,发现该菌株对多种植物病原性真菌及细菌有拮抗作用.通过形态特征、培养特征观察,生理生化特性及抑菌谱等系列比较.发现该菌株与链霉菌属的除虫链霉菌(Streptomyces avermitilis)的特征基本相符;通过16s rDAN序列比对,发现该菌株16s rDAN与除虫链霉菌的16s rDAN同源性达99%.根据多项分类原则和系统进化树的构建分析,将该菌株暂归入除虫链霉菌类.     

轮丝链霉菌(Streptomyces Ys.03)代谢产物的抗植物病毒活性及其分类鉴定

[目的]1株从土壤中分离得到的放线菌的抗植物病毒活性及其分类鉴定。[方法]室内对峙培养、枯斑和系统寄主的保护及治疗试验,菌株形态观察并结合培养特征、生理生化性状及16S rDNA序列测定。[结果]菌株Ys.03对蜡状芽孢杆菌有稳定的拮抗作用;发酵液与烟草花叶病毒(TMV)混合后接种枯斑和系统寄主,对TMV抑制率分别为95.01%和88.67%;接种前、后叶面分别喷施发酵液抑制率均较高;菌株孢子链轮生,16S rDNA测序与师岗轮丝链霉菌(Streptomyces mormookaensis)同源性达100%。[结论]菌株Ys.03代谢产物对TMV有显著的抑制作用,鉴定为链霉菌属轮生类群师岗轮丝链霉菌。     

添加氧载体促进林可霉素发酵过程的研究

为了有效的改善林可霉素发酵液中的氧传递速率,研究了氧载体对林可霉素发酵的影响。结果表明,正十二烷作为氧载体的效果较好,能有效提高林肯链霉菌发酵合成林可霉素的能力。在发酵开始的第24 h添加4%的正十二烷,在摇瓶和发酵罐中发酵,可以分别提高林可霉素的效价26.3%和28.8%。     

Streptomyces aminopeptidase P: biochemical characterization and insight into the roles of its N-terminal domain

We purified and characterized the aminopeptidase P from Streptomyces costaricanus TH-4 (thAPP). This enzyme has a tetramer structure, a metal-ion preference toward Zn, broad substrate specificity and a narrow pH dependency for activity. The primary structure of thAPP, respectively, exhibits 91% and 65% identity with those of two other APPs-APP I and APP II-from Streptomyces lividans (slAPP I and slAPP II). We next overexpressed the genes encoding thAPP and slAPP II in Escherichia coli and characterized them. Two differences were apparent in their properties: slAPP II formed a dimer, whereas thAPP formed a tetramer; also, the alkaline side pKa for the catalytic action of slAPP II is higher than that of thAPP. Investigation using chimeras of both enzymes revealed that the N-terminal domain is associated with the determination of pKa values for catalytic action and quaternary structure.     

放线菌A2菌株代谢产物的研究初报

从渤海海水中分离到一株编号为A2的放线菌,经初步鉴定为链霉菌（Streptomyces）。该菌株产生的代谢产物对许多重要农作物病害具有强烈的抑制作用。采用菌丝生长速率法测定其对小麦赤霉病菌、烟草赤星病菌、番茄灰霉病菌、马铃薯干腐病菌的菌丝生长影响,抑制率达到90％以上;孢子萌发法测定其对烟草赤星病菌、小麦赤霉病菌和马铃薯干腐病菌的孢子萌发的影响,抑制率都在90％以上。盆栽试验结果表明,发酵产物对小麦白粉病的保护和治疗作用分别为98.31％、96．56％。经pH纸色谱和捷克八溶剂系统纸层析实验,初步推定A2所产生的抗牛素为碱性水溶性抗牛素。     

航天诱变提高Streptomyces gilvosporeus的那他霉素产量

Mutants of the strain producing natamycin, Streptomyces gilvosporeus, were obtained after space-flight mutation. With respect to the sand spores and slant spores, the mutation ratios were up to 67.6% and 78.3% and the survival ratio was 43.1% and 3.0%, respectively. An improved mutant producing natamycin, S. gilvosporeus LK-45, was screened, which showed natamycin productivity of 1420mg·L^-1. A mutant resistant to 2-deoxy glucose, S.gilvosporeus LK-119, was further obtained using a＇rational screening procedure. The natamycin productivity of 1940mg·L^-1 was achieved when glucose was used as the carbon source.     

黄霉素工业化发酵过程中灰色预测模型的应用

将灰色预测模型应用于黄霉素工业化发酵过程中。对采用Streptomyces bambergiensis 在60 m3发酵罐中批式补料发酵生产黄霉素的过程分别建立GM（1,8）、GM（1,1）和灰色Verhulst模型。3种模型的预测模拟结果表明都可以模拟黄霉素工业化发酵过程,其平均相对误差分别为15.322%、6.093%和1.776%,残差平方和分别为4.177 g2/L2、0.680 g2/L2和0.053 g2/L2。通过比较3种模型预测模拟结果证明灰色Verhulst模型更适合黄霉素工业化发酵过程的预测模拟。     

Changes in the microstructure and enzymatic hydrolysis performance of chitin treated by steam explosion,high-pressure homogenization,and γ radiation

This research intends to reduce the crystallinity of chitin with physical methods so as to improve the enzymatic hydrolysis efficiency of chitin. Scanning electron microscopy showed that both steam explosion and high-pressure homogenization significantly enlarged the pores in shrimp shells, which are made up of chitin, but γ radiation did not. X-ray diffraction showed that the crystallinity index of chitin decreased by 23.2% in the (110) plane and 24.7% in the (020) plane after three rounds of steam explosion and decreased by 12.4% in the (110) plane and 28.7% in the (020) plane after three rounds of high-pressure homogenization. After γ radiation, however, there was no significant change. The corresponding deacetylation degrees of the chitin treated with steam explosion and high-pressure homogenization increased by 13.2 and 5.7%, respectively. The natural, steam-exploded and high-pressure homogenized chitins respectively produced 0.251, 0.145, and 0.407 mg/ml reducing sugars with the hydrolysis of Streptomyces griseus chitinase. However, when hydrolyzed by Paenibacillus sp. A1 chitinase the steam-exploded and the high-pressure homogenized chitin respectively released 40 and 300% more reducing sugars than the natural chitin. The results found that steam explosion and high-pressure homogenization can reduce the crystallinity of chitin, and make it prone to enzymatic hydrolysis.     

Non-colinear polyketide biosynthesis in the aureothin and neoaureothin pathways: an evolutionary perspective

Aureothin and neoaureothin (spectinabilin) represent rare nitroaryl-substituted polyketide metabolites from Streptomyces thioluteus and Streptomyces orinoci, respectively, which only differ in the lengths of the polyene backbones. Cloning and sequencing of the 39 kb neoaureothin (nor) biosynthesis gene cluster and its comparison with the aureothin (aur) pathway genes revealed that both polyketide synthase (PKS) assembly lines are remarkably similar. In both cases the module architecture breaks with the principle of colinearity, as individual PKS modules are used in an iterative fashion. Parsimony and neighbour-joining phylogenetic studies provided insights into the evolutionary process that led to the programming of these unusual type I PKS systems and to prediction of which modules act iteratively. The iterative function of the first module in the neoaureothin pathway, NorA, was confirmed by a successful cross-complementation.