烟草青枯病生防菌的筛选及其田间防效评价

为筛选出对烟草青枯病有效防治的生防菌,通过稀释涂布法从烟株根际土壤分离到一株具有明显拮抗作用的菌株69-1,经16S rDNA鉴定该菌株为壮观链霉菌(Streptomyces spectabilis),并用该菌株进行烟草青枯病田间防治试验。结果表明,与对照相比,经菌株69-1处理烟株茎围、有效叶片数、最大叶宽、最大叶长、上中下部烟叶单叶干重、最大叶面积、产量均显著增加,且对烟草青枯病的相对防效达60.42%,同时对不同处理组的初烤烟叶进行化学成分的检测分析,发现菌株69-1处理相对于对照组烟叶品质更佳。该菌株菌剂处理不仅可以提高烟株对烟草青枯病的防效,而且还提高烟叶品质和产量,可为烟草青枯病生物防治提供一定参考。     

Enzyme Bioprospection of Marine-Derived Actinobacteria from the Chilean Coast and New Insight in the Mechanism of Keratin Degradation in Streptomyces sp. G11C

Marine actinobacteria are viewed as a promising source of enzymes with potential technological applications. They contribute to the turnover of complex biopolymers, such as pectin, lignocellulose, chitin, and keratin, being able to secrete a wide variety of extracellular enzymes. Among these, keratinases are a valuable alternative for recycling keratin-rich waste, which is generated in large quantities by the poultry industry. In this work, we explored the biocatalytic potential of 75 marine-derived actinobacterial strains, focusing mainly on the search for keratinases. A major part of the strains secreted industrially important enzymes, such as proteases, lipases, cellulases, amylases, and keratinases. Among these, we identified two streptomycete strains that presented great potential for recycling keratin wastes—Streptomyces sp. CHA1 and Streptomyces sp. G11C. Substrate concentration, incubation temperature, and, to a lesser extent, inoculum size were found to be important parameters that influenced the production of keratinolytic enzymes in both strains. In addition, proteomic analysis of culture broths from Streptomyces sp. G11C on turkey feathers showed a high abundance and diversity of peptidases, belonging mainly to the serine and metallo-superfamilies. Two proteases from families S08 and M06 were highly expressed. These results contributed to elucidate the mechanism of keratin degradation mediated by streptomycetes.     

链霉菌和壳聚糖对淮山土壤微生物活性与群落的影响

为探究链霉菌30702和壳聚糖对淮山土壤微生物活性与群落的影响,采用比色法和滴定法观测土壤酶活性的变化,采用高通量测序技术和Trimmomatic等软件,分析土壤微生物群落中细菌和真菌的发展变化。结果表明,链霉菌、壳聚糖、土壤原始微生物和培养时间等4个因素对淮山土壤的脲酶和过氧化氢酶活性均有显著影响,壳聚糖浓度在0~10.0 g/kg内,土壤酶活性随壳聚糖浓度的增大而提高;随时间的延长,先升再降;壳聚糖与链霉菌之间存在交互效应。链霉菌和壳聚糖能增加淮山土壤细菌的物种丰度,减少细菌的多样性,增加艾德昂菌属（Ideonella）和纤维弧菌（Cellvibrio）等有益菌属的相对丰度,而对真菌的物种丰度和多样性的影响较小,与对照之间的差异不显著,土壤优势菌属为腐质霉属（Humicola）、枝孢属（Cladosporium）、鞘氨醇单胞菌属（Sphingomonas）和uncultured_bacterium_ c_Subgroup_6。其中,链霉菌与2.5 g/kg壳聚糖复合处理的细菌物种丰度最大,细菌多样性最少。     

变铅青链霉菌DNA的研究——Ⅱ.位点特异性降解与DNA修饰的关系

变铅青链霉菌的DNA上存在着一种异常的修饰,使其在含有微量Fe~(++)的缓冲液中电泳时,双链DNA遭到降解。DNA的切割是位点特异性的。与已知修饰特征的DNA进行同步试验发现,变铅青链霉菌的这种特异性修饰与目前所发现的修饰系统(如DNA甲基化)均不相同,很可能是一种新的修饰系统。     

增效浏阳霉素防治叶螨的效果和对智利植绥螨影响的研究

在实验室内用5％增效浏阳霉素乳油1000倍液防治截形叶螨,24小时后的死亡率为95.5％。对三氯杀螨醇有较强抗性的二斑叶螨和朱砂叶螨,48小时后的死亡率也达90％左右。浏阳霉素对3种叶螨均无杀卵作用,但施药5～6天后,对初孵幼螨仍能杀死90％以上。低温能降低浏阳霉素的药效。在温室中施药一周后。对二斑叶螨的雌成螨无残效,但幼螨和前若螨的死亡率可达97.4％。以磷酸兰苯酯作增效剂的浏阳霉素比亚磷酸三苯酯作增效剂的药效好。在同一剂量下,对二斑叶螨的死亡率分别为98.2％和53.4％。5％浏阳霉素的1000倍液对智利植绥螨成螨的生存率、在叶上的定居率及着卵量均无影响。在温室栽培月季上喷药1次防治二斑叶螨,36天后防治效果仍保持在99％,而用三氯杀螨醇和敌敌畏防治,施药一周后需再次防治。     

马铃薯疮痂病菌毒素及其致病性的研究

 本文对分离自我国不同地区的马铃薯疮痂病菌产生的毒素进行了研究。通过对不同菌株进行毒素提取、纯化和产毒分析发现各致病菌株均能产生同一类毒素,而非致病菌株均未见毒素产生。毒素的活性检测结果表明,毒素能使马铃薯薯片和萝卜幼苗产生与病菌作用相同的症状,说明毒素是疮痂病菌侵染过程中的主要致病因子。     

A 9-year monitoring study of diseases on potato seed tubers imported to Israel

Potato seed tubers are imported annually to Israel from northern Europe. Although the seed is registered as certified, a survey carried out over a 9-year period indicated that most lots were affected by latent or active bacterial and fungal infections. Latent infection byErwinia carotovora subsp.atroseptica, the causal agent of blackleg, at a level of 10³ cells/g peel, was present in 30% of the lots in most years. Black scurf caused byRhizoctonia solani was present in 20–70% of the imported lots, with a moderate to high level of infection in all years except 1985. In contrast, although many lots were affected by powdery scab, common scab, and Fusarium dry rot in most years, disease incidence within lots was generally low. The gangrene pathogen (Phoma exigua) was rarely detected. The survey findings are of marked importance, due to the extensive use of soil fumigation in Israeli agriculture.     

不同时期使用农抗120控制花生网斑病侵染源的试验研究

用农抗120防治花生网斑病,不同使用方法效果不一。用常规喷洒叶面方法控制再侵染源,防效为21.4％,相当于多菌灵(29.4％);用农抗120和杀菌剂(抗枯灵或多菌灵等)混合,在花生播种时喷洒地面一次,控制初侵染源,防效为48.6％,用农抗120同杀菌剂混合,播种时喷洒地面,以控制初侵染源,7月上旬再喷洒叶面,控制再侵染源,效果最佳,防效高达70％以上。     

生防菌株Men-myco-93-63发酵培养条件研究

对生防链霉菌Men-myco-93-63进行了摇瓶培养条件试验。结果表明,培养温度30℃,培养基初始pH值7.5,500ml三角瓶装液100ml,摇床转速200r/min为最适摇瓶发酵培养条件。在优化的培养条件基础上进行了摇瓶中代谢情况的测定,并在摇瓶试验的基础上进行了30L发酵罐试验,为进一步发酵规模化生产奠定了基础。     

紫外-光复活诱变香兰素生产菌株的研究

[目的]探究紫外诱变和光复活修复对生产香兰素菌株的效果。[方法]通过紫外诱变和光复活修复对香兰素生产菌链霉菌(Streptomycessp.L1936)进行复合诱变,筛选出香兰素高产菌株(Streptomycessp.L1936-9)。[结果]出发菌株经过紫外诱变和光复活修复处理后,脱乙酰酶酶活提高了71.1%,香兰素氧化酶酶活降低了34.6%相应的香兰素产量提高了34.2%。[结论]该研究为香兰素生产提供了良好途径。