拟康氏木霉(Trichoderma pseudokoningii)UV III纤维素酶合成的诱导与阻遏

拟康氏木霉 (T .pseudokoningii)TH经紫外诱变获得一抗高浓度葡萄糖阻遏突变株UVIII,纤维素酶产量显著提高。研究表明 ,UVIII对诱导物的敏感性增加了 10 0倍 ,并且对葡萄糖的吸收能力明显下降 ,导致部分解除了葡萄糖阻遏作用 ,这可能都是该突变株产酶提高的原因     

Relationship of in vitro and in planta screening: improving the selection process for biological control agents against Fusarium root rot in row crops

Fusarium root rot in row crops is typically managed by cultural practices and fungicide seed treatments. Biological control using microbial agents is another option but needs further development for improved disease management. Screening to identify biocontrol agents are crucial. However, relationships among the steps and how to improve the screening process are unresolved questions. Strains of Burkholderia (4), Bacillus (5) and Trichoderma (26) were studied in vitro against six Fusarium pathogens. All the bacteria and five selected Trichoderma strains were tested in planta in the greenhouse against diseases of Fusarium graminearum and Fusarium oxysporum. Burkholderia ambifaria C628, Bacillus simplex R180, and all Trichoderma isolates showed high reduction in disease levels in corn, soybean and wheat, ranging from 16 to 63%. Responses of the biocontrol agents during in vitro and in planta screening did not always correlate. In vitro and in planta tests should be considered independently in selecting biocontrol candidates.     

New Syntheses of (R)-(+)-3-Acetoxy-2,6-dimethyl-l,5-heptadiene,the Pheromone of the Comstock Mealybug

L-Phenylalanine was converted to optically impure (R)-(+)-2,6-dimethyl-1,5-heptadien-3-ol 2 (19% e.e.) .(R)-(+)-2 (96% e.e.) was prepared by a kinetic resolution of (±)-2. Acetylation of the pure (R)-(+ )- 2 gave the pheromone of the Comstock mealybug ( Pseudococcus comstockii KUWANA) [(R)-(+)-1].     

拟康氏木霉(Trichoderma psudodoningii)UV III产纤维素酶液体发酵研究

以拟康氏木霉(Trichoderma psudodoningii)TH为出发菌株,经紫外诱变荻得一抗高浓度葡萄糖阻遏突变株uV III,其液体发酵最适产酶培养基为(w/V)豆皮粉3%,硝酸铵0.6%,磷酸二氢钠0.65%,硫酸镁0.25%,氯化钙0.15%,pH5.0;最佳发酵条件为30℃,125r/min发酵7d CMCase活力可达103.55 IU/mL,滤纸酶活可达5.51 IU/mL,β一葡萄糖苷酶活可达0 96IU/mL,分别比出发菌株TH提高了1.40、2.34、0.60倍.     

色氨酸残基在内切葡聚糖酶分子中的作用

内切葡聚糖酶的化学修饰研究表明：色氨酸残基可能位于活性位点,与底物结合有关．荧光光谱测定指出该酶的荧光几乎都来自色氨酸残基,酶分子中色氨酸微环境对ｐＨ变化非常敏感,降低ｐＨ导致了酶分子构象发生了较大变化,配基结合使酶分子色氨酸微环境产生了改变,引发了与ｐＨ诱导不同的构象变化．     

木霉菌对3种致病真菌的作用关系研究

采用室内生长速率法测定了木霉菌 (Trichodermaspp .)与 3种致病真菌的互作关系 ,结果表明 ,木霉菌与 3种致病真菌间均存在明显的互作关系 ,但其互作类型与作用强度各不相同 :木霉菌与立枯丝核菌 (Rhi zoctoniasolani)间存在拮抗作用 ,但抑制强度不大 ;木霉菌与腐霉菌 (Pythiumaphanidermatum)不仅存在拮抗作用 ,且对腐霉菌的抑制强度较大 ;木霉菌与镰刀菌 (Fuariumspp .)间存在明显的协生作用。经进一步多方面考察后 ,有可能将该木霉菌用于病害防治     

T90-1木霉菌的筛选和对草莓灰霉病菌作用机制的研究

木霉菌（Trichoderma）作为一种重要的生防因子,可以产生几丁质酶降解植物的多种病原真菌细胞壁。利用低能离子束注入木霉菌使其产生变异,再通过初筛选和复筛选两个过程,获得T90_1木霉菌株,并用草莓灰霉病菌（Botrytis cinerea Pers.）来检验T90_1防治真菌病害的能力。发现该菌株通过侵染、缠绕等多种重寄生方式,并分泌降解病原真菌细胞壁的物质,使病原菌原生质外渗,改变细胞内有序的代谢状况,从而抑制或杀死病原菌。初步揭示该菌株抗真菌的相关机制。     

木霉LaTr 01菌株产漆酶发酵的条件

从华南地区采集土样,采用愈创木酚平板筛选产漆酶菌株,获得了一株短周期产漆酶的小型丝状真菌。通过观察菌落特征、生长情况以及显微镜下菌丝和孢子的形态,初步鉴定该菌株为木霉属的一个种（Trichodermaspp、）,命名为木霉LaTr01菌株。通过单因素方法研究该菌产漆酶的发酵条件,结果表明：LaTr01的产酶培养基以麦芽糖为最佳碳源;以酵母提取物为最适氮源;培养24h后加入Cu“比培养开始加入Cu ^2＋LaTr01产酶活高出约1倍。采用麦芽糖、酵母提取物、Cu^2＋浓度L9（3^3）的正交试验优化漆酶发酵条件,结果表明,氮源是影响该菌产漆酶的最重要因素,碳源次之,Cu^＋浓度影响较小;LaTr01菌株产生漆酶的最佳条件为：5g／L酵母提取物、20g/L麦芽糖、1．5mmol／LCu^2＋,Cu^2＋加入时间为培养24h后。在优化的培养条件下,该菌酶活可达480．556U／L。     

Intraspecific hybridisation of Trichoderma pseudokoningii by anastomosis and by protoplast fusion

Double auxotrophic and morphological mutants of Trichoderma pseudokoningii Rifai were fused by anastomosis and by protoplast fusion. The recovery of recombinants from heterokaryons on different selective media and from heterokaryotic colonies indicated the occurrence of parasexual events. Prototrophic colonies growing on minimal medium produced binucleate spores, green in colour, revealing a non-autonomous system for conidial pigmentation. Recombinants were obtained from these dikaryotic colonies suggesting the occurrence of a highly unstable diploid phase.     

Assessment of suitability and suppressiveness of on-farm green compost as a substitute of peat in the production of lavender plants

Suppression of root rot diseases of ornamental plants is a potential benefit of formulating soilless container media with compost. A green compost (green nursery compost, GNC), obtained by a circular-economy approach from residues of pruning of woody plants and grass clippings during the nursery activities was analysed for its suppressiveness of root rot diseases using lavender. To this end, a bioassay was develop by formulating potting mixes containing GNC with two rates of peat substitution (25% and 50%) and infested with the root rot pathogens Sclerotinia sclerotiorum, Rhizoctonia solani and Phytophthora nicotianae. Contrasting results were obtained by using both substrates with a significant reduction of root rot by S. sclerotiorum, no effect on the containment of that by P. nicotianae, and an increase of symptoms caused by R. solani. The specific suppressiveness observed may be attributed to the colonisation of compost by specific groups of antagonistic microorganisms. This hypothesis was investigated by the analysis of culturable fungal community, which resulted in the isolation of Trichoderma harzianum and T. atroviride as preponderant fungal species. Trichoderma representative isolates exerted in vitro antagonistic activities against the target pathogens with varying efficiencies indicating the employment of multiple complementary mechanisms, which may have contributed to the observed specific suppressiveness. Both substrates containing GNC resulted suitable for nursery cultivation of lavender, showing a growth performance similar to that obtained with peat-based substrate. Present results indicate that on-farm compost is a suitable component of mixed-peat substrates capable to support plant growth and provide specific disease suppression.