拮抗链霉菌NW136菌株鉴定及其对番茄灰霉病等真菌病害的控制效果

从陕北地区的土壤放线菌样品中分离到一株链霉菌NW136。该菌株的形态特征、培养特征、生理生化特征与已报道的近似种不同,而与微白链霉菌相似。室内和田间试验表明,它所产生的抗生素对番茄灰霉病等具有良好的防治效果。     

2株内生拮抗细菌对灰霉病菌的抑菌活性研究

采用对峙培养法检测了2株内生拮抗细菌对灰霉病菌菌丝生长的影响,并观察了其发酵液对灰霉病菌孢子萌发及病菌生长的影响,同时测定了其发酵液、细菌悬浮液以及高温处理的发酵液在离体黄瓜上对灰霉病菌生长的抑制作用。结果表明：2菌株能强烈抑制灰霉病菌生长,其发酵液也能明显抑制病菌孢子的萌发和生长,且发酵液高温处理后仍具有较高的抑菌活性。在离体黄瓜片上检测菌株对灰霉病菌的抑制效果,结果表明,2菌株发酵液及其细菌悬浮液均能较好地抑制灰霉病菌生长。     

11种木霉菌对葡萄灰霉病菌的拮抗作用

对采自宁夏14个市县的170份土样及其它材料进行分离,得到96株木霉菌株,采用形态分类方法鉴定出9种木霉菌以及2种未知名菌种,它们分别为哈茨木霉（Trichoderma harzianum）、绿色木霉（T.viride）、长枝木霉（T.longibrachiatum）、康氏木霉（T.koningii）、拟康氏木霉（T.pseudokoningii）、顶孢木霉（T.fertile）、黄绿木霉（T.aureoviride）、深绿木霉（T.atroviride）、钩状木霉（T.hamatum）以及T.sp1和T.sp2。竞争及对峙培养结果表明：11种木霉菌种对葡萄灰霉病菌(Botrytis cinerea Pers.)均有不同程度的拮抗作用,尤其前四种木霉菌表现出了很强的竞争优势,在对峙培养中对葡萄灰霉菌的拮抗系数为Ⅰ~Ⅱ,抑菌率达61.8%~77.6%。在光学显微镜下可观察到木霉菌或缠绕或穿入葡萄灰霉菌菌丝生长,并发生菌丝断裂、消解以及细胞原生质浓缩等现象     

异株克生因素对生物固氮的作用

异株克生来源的生理活性物质对植株—固氮菌这一宏微观共生体间的相互作用、共生或联合固氮关系的形成、发展及有效性起着重要的作用 ,及其生产实践意义     

黄绿木霉诱变菌株对大豆根腐病镰刀菌的拮抗

以黄绿木霉(Trichoderma aureoviride)为出发茵株,孢子经紫外线照射,亚硝酸及氯化锂复合处理后获得一株酶活增强的突变株.通过对峙培养与发酵液处理病原茵研究了该诱变株对大豆根腐病几种镰刀茵(Fusarium spp.)的拮抗作用.诱变株经传代30代后,其产酶活性仍保持增强,生防能力有所提高.拮抗试验结果明确了黄绿木霉诱变株对镰刀茵的拮抗机理以生存竞争和接触后对病原茵茵丝破坏的溶菌作用为主,且诱变株产孢速度快,分生孢子梗空间竞争优势强于原始茵株.酶活测定结果表明,诱变株的滤纸酶活提高85.7%,CMC-Na酶活提高26.7%,β-葡萄糖苷酶活提高130.3%.     

土壤中木霉的分离纯化以及对植物病原真菌的拮抗研究

从土壤中分离纯化获得3个木霉集合种:哈茨木霉(Trichoderma harzianum),绿色木霉(Trichoder-ma viride)和绿木霉(Trichoderma virens)。用这3种木霉菌分别与小麦纹枯病菌(Rhizoctonia solania)和番茄灰霉病菌(Botrytis cinerea)作平板对峙培养及显微观察,测定木霉菌对病原菌的抑制作用。结果表明:3种木霉菌对供试的2种病原菌抑菌强度不同,其中绿木霉对小麦纹枯病菌和番茄灰霉病菌都具有较好的拮抗作用;显微观察到木霉菌对病原菌菌丝的缠绕、使病原菌菌丝细胞质变稀薄、菌丝解体等现象。     

辣椒疫病拮抗菌的分离、筛选与评价

从67份不同土样中分离得到382株细菌、264株放线分离物,通过平板时峙培养,筛选出拮抗辣椒疫霉的株,其中放线的比例较高,为44.1%;而细菌所占比例则较低,仅为8.5%.测定了抑活性较强的26株株对6种植物病原真的拮抗作用及盆栽控病效果.试验结果表明,拮抗B-YD4-6,A-NP6-7和A-GD5-2对6种植物病原真菌均有抑作用.且抑能力较强,抑圈直径为22.0～26.0 mm,抑制率达45.18%～55.56%;且该3株拮抗株对辣椒疫病的防治效果较好,21 d后的防治效果分别为65.5%,67.4%,64.5%.     

Effect of manganese-reducing rhizosphere bacteria on the growth of Gaeumannomyces graminis var. tritici and on manganese uptake by wheat (Triticum aestivum L.)

Summary Five bacterial strains capable of Mn reduction were isolated from the rhizosphere of plants growing in different South Australian soils. They differed in their Mn-reducing capacity. The antagonism of these strains compared to the imported strain 2–79 (from the United States) against Gaeumannomyces graminis var. tritici was tested in agar and in a soil sandwich experiment at different Mn²⁺ concentrations in the soil. In addition, wheat seeds were coated with the different strains and with MnSO₄ or with MnSO₄ only in order to investigate their effect on plant growth and Mn uptake. With one exception, all strains inhibited the growth of G. graminis in agar, but to different degrees. In contrast, only two strains significantly inhibited the growth of the fungus in the soil. The hyphal density was decreased more than the hyphal length. The Mn²⁺ concentration in the soil also had a marked effect on fungal growth; low Mn concentrations slightly increased while high Mn concentrations strongly decreased the fungal growth. Seed treatment with MnSO₄ only (+Mn) increased Mn uptake above that of the control (no seed treatment). Only the weakest Mn reducer on agar significantly increased plant growth and Mn uptake from soil in comparison with the Mn treatment. One strain was tested as seed coating without adding MnSO₄; it increased the plant growth to an extent similar to the Mn treatment. Increasing the Mn uptake by plants may be one of the growth-promoting effects exerted by rhizosphere bacteria.     

ETPMG极端嗜热多肽N-末端氨基酸测序及其对苗瘟的防效

本试验用加热法从多粘类芽孢杆菌(Paenibacillus polymyxa)LM-3菌株的发酵液中纯化得到2个极端嗜热多肽.平板拮抗实验表明,5μL纯化多肽对稻瘟病菌(Magnaporthe grisea)抑菌率达89.6%.SDS-PAGE电泳显示纯化多肽分子量介于6 000～7 000 D之间.多肽复性后,其中之一对稻瘟病菌表现出强的拮抗活性,命名为ETPMG(extreme thermophilic polypeptide against M. grisea);另一个则无此活性,命名为ETPL3(extreme thermophilic polypeptide from LM-3).ETPMG经氨基酸测序,获得了其N-末端5个氨基酸序列(H2N-ANDPR).以ETPMG为主效成分配得5种微生物源生防乳剂,对水稻苗瘟进行了田间防效试验.试验结果表明,这5种乳剂的防效都优于LM-3拮抗液直接喷雾,其中处理AB4的防效最佳,达80.73%,其拮抗成分、吐温80、乳化剂OP、溶剂的质量比为50∶6.5∶1.75∶41.75.ETPMG为首次报道的兼具极端嗜热性和稻瘟病菌拮抗活性的小分子多肽.     

Antimicrobial synergism and antagonism of salicylaldehyde in Filipendula vulgaris essential oil

The leaf essential oil of Filipendula vulgaris, consisting mainly of salicylaldehyde (68.6%), was screened for its antimicrobial activity by the disk diffusion and microdilution broth assays. The essential oil remarkably inhibited the growth of all of the tested bacteria and fungi. It seems that the antimicrobial nature of F. vulgaris essential oil can be attributed to the synergistic interactions of the compounds constituting the oil rather than to the presence of a single inhibitory agent. A synergy in salicylaldehyde/linalool mixtures was observed with a maximum interaction situated in the range between 60:40 and 80:20 (mol ratio). At this concentration range (at a dose of 1.7 microg/disk) no microbial growth was observed while the respective pure compounds, at the corresponding quantities, are shown to be dramatically less active. The MIC value for the 60:40 mixture was determined to be less that 0.009 mg/ml. In addition, an antagonistic relationship between salicylaldehyde and methyl salicylate was established. The maximum (negative) interaction was shown to correspond approximately to the mixture at the 40:60 (methyl salicylate/salicylaldehyde) mol ratio resulting in the complete loss of activity at the investigated dose.