杨树根癌病原菌拮抗链霉菌的筛选

通过对杨树根癌病发病根系土样及健康根系土样链霉菌进行分离,得到63株链霉菌。并且使用纸片法测定了链霉菌及其无菌发酵滤液对根癌土壤杆菌的抑菌能力,得到有拮抗效果的链霉菌17株,其中5株链霉菌平板抑菌能力较强,抑菌圈直径大于3.0 cm。但这5株链霉菌无菌发酵滤液拮抗能力下降,甚至不表现抑菌活性。     

Youssoufenes A2 and A3, Antibiotic Dimeric Cinnamoyl Lipids from the ΔdtlA Mutant of a Marine-Derived Streptomyces Strain

Two new dimeric cinnamoyl lipids (CL) featuring with an unusual dearomatic carbon-bridge, named youssoufenes A2 (1) and A3 (2), were isolated from the ΔdtlA mutant strain of marine-derived Streptomyces youssoufiensis OUC6819. Structures of the isolated compounds were elucidated based on extensive MS and NMR spectroscopic analyses, and their absolute configurations were determined by combination of the long-range NOE-based ¹H-¹H distance measurements and ECD calculations. Compounds 1 and 2 exhibited moderate growth inhibition against multi-drug-resistant Enterococcus faecalis CCARM 5172 with an MIC value of 22.2 μM.     

Secondary Metabolites and Biosynthetic Gene Clusters Analysis of Deep-Sea Hydrothermal Vent-Derived Streptomyces sp. SCSIO ZS0520

Streptomyces sp. SCSIO ZS0520 is a deep-sea hydrothermal vent-derived actinomycete. Our previous metabolism investigation showed that Streptomyces sp. SCSIO ZS0520 is a producer of cytotoxic actinopyrones. Here, another four types of secondary metabolites were identified, including six salinomycin isomers (2–7), the macrolide elaiophylin (8), the triterpene N-acetyl-aminobacteriohopanetriol (9), and the pyrone minipyrone (10). Among them, compounds 2–6 and 10 are new compounds. To understand the biosynthetic pathway of these compounds, a bioinformatic analysis of the whole genome was carried out, which identified 34 secondary metabolite biosynthetic gene clusters. Next, the biosynthetic pathways responsive to four types of products were deduced on the basis of gene function predictions and structure information. Taken together, these findings prove the metabolite potential of ZS0520 and lay the foundations to solve the remaining biosynthetic issues in four types of marine natural products.     

马铃薯干腐病菌拮抗放线菌JY-22的抑菌作用及菌株鉴定

为了进一步明确拮抗放线菌JY-22对马铃薯干腐病的生防潜力,采用生长速率法和孢子萌发法测定了JY-22无菌发酵液(JY-22SFB)对马铃薯干腐病菌的抑菌作用及抑菌活性稳定性。JY-22SFB原液对马铃薯干腐病菌菌丝生长和孢子萌发均有很强的抑制作用,抑制率分别为74.5%和100%,其中对孢子萌发的抑制效果与浓度为30 mg/mL的化学药剂50%多菌灵相当。JY-22SFB处理后马铃薯干腐病菌菌丝生长畸形、易断裂。JY-22SFB对热处理和紫外线照射处理具有很好的稳定性,水浴80℃处理3 h和紫外线照射30 min对其抑菌活性没有影响。JY-22SFB浸泡处理可明显降低马铃薯干腐病菌的致病性。通过形态和分子鉴定,确定该菌属链霉菌属吸水链霉菌Streptomy-ces hygroscopicus。研究表明菌株JY-22在马铃薯干腐病生物防治中具有潜在的利用价值。     

杨树烂皮病生防链霉菌的筛选及鉴定

为明确能有效抑制杨树烂皮病菌的拮抗放线菌F58的生防效果及分类地位,采用平板对峙法、杯碟法和人工接种法分别测定了其活菌及发酵液的抑菌活性;并通过形态学、生理生化特征、16S rRNA及全细胞脂肪酸分析等方法研究了其分类地位。结果表明,拮抗放线菌F58对杨树烂皮病菌、杨树溃疡病菌、苹果斑点落叶病菌等13种供试植物病原菌均有抑制作用,抑菌谱广,其中对杨树烂皮病菌和杨树溃疡病菌抑制作用最强,抑菌带达30.2 mm以上,菌株F58发酵液对这2种病菌也有很强的抑制作用,抑菌圈直径分别为56.4 mm和42.7 mm;发酵液的无菌滤液对杨树烂皮病的保护效果和治疗效果分别达88.7%和73.4%。根据菌株形态、生理生化特性、16S rRNA序列比对及全细胞脂肪酸分析,鉴定拮抗放线菌F58为盐屋链霉菌Streptomyces sioyaensis。     

暗黑链霉菌PY-1活性产物分析及其对葡萄霜霉病田间防效评价

为探究暗黑链霉菌Streptomyces atratus PY-1对葡萄霜霉病菌Plasomopara viticola的抑制作用,通过扫描电镜观察PY-1发酵滤液对葡萄霜霉病菌孢子囊的影响,检测PY-1的活性物质种类,并测定其对葡萄霜霉病的田间防效。结果表明,PY-1发酵滤液能够导致葡萄霜霉病菌孢子囊和孢子囊梗出现褶皱、破裂和畸形,进而使其丧失侵染功能。PY-1菌株代谢产物中包含几丁质酶、蛋白酶、嗜铁素、1-氨基环丙烷-1-羧酸脱氨酶、氰化氢、吲哚乙酸,不含纤维素酶。PY-1菌株对葡萄霜霉病具有较好的田间防效,发酵原液对葡萄霜霉病的田间中期防效可达到89.17%以上,末期防效达86.28%以上,比52.5%噁唑菌酮·霜脲氰2 000倍液的防效略低,但显著高于58%甲霜·锰锌1 000倍液的防效;PY-1菌株发酵液稀释700倍后对葡萄霜霉病的末期防效与甲霜锰锌1 000倍液防效相当。表明PY-1菌株具有研制防治葡萄霜霉病生防制剂的潜力。     

暗黑链霉菌PY-1抑菌活性产物的结构鉴定及其对葡萄霜霉病菌的抑制作用

 从暗黑链霉菌(Streptomyces atratus)PY-1菌株发酵液中分离鉴定抑菌活性产物,评价其对葡萄霜霉病菌(Plasmopara viticola)的抑制作用,为该菌株及其产生的抑菌活性物质的应用提供依据。PY-1菌株发酵液经二氯甲烷萃取,减压浓缩获得抑菌粗提物,稳定性测定结果显示,避光条件下,15℃~65℃、pH 6~10、4℃或常温保存6个月,抑菌活性稳定。采用硅胶柱层析、Sephadex LH-2柱层析、薄层层析和HPLC等技术,对抑菌粗提物进一步分离纯化,得到2种抑菌活性组分;采用ESI-MS、¹H NMR、¹³C NMR等波谱分析技术,对活性组分进行结构鉴定,2种活性组分分别鉴定为5-乙酸环已基酰亚胺(5-acetoxycycloheximide)和环己酰亚胺(cycloheximide)。采用离体叶片法测定2种组分的抑菌活性,不同浓度(10⁴ ng·mL^-1、10² ng·mL^-1、1 ng·mL^-1)的5-乙酸环已基酰亚胺和环己酰亚胺对葡萄霜霉病菌的抑制作用分别为92.59%、86.30%、64.81%和97.04%、91.85%、84.07%。     

拮抗放线菌B1菌株鉴定及其防治番茄灰霉病的初步研究

为明确放线菌B1菌株在植物病害生物防治中的应用潜力,采用平板对峙培养法、离体叶片和果实及温室盆栽苗测定其抑菌作用,通过多相分类法研究其分类地位,并且采用单因子试验与正交试验相结合的方法,筛选出该菌株的液体发酵培养基配方.结果表明:菌株B1对10种植物病原真菌和3种植物病原细菌有抑制作用,其中对番茄灰霉病菌、番茄早疫病菌、小麦纹枯病菌、甘蓝黑腐病菌和西瓜果腐病菌的抑制作用较强,对番茄灰霉病菌的生长抑制率达86.25%;菌株B1的代谢产物对番茄灰霉病菌菌丝有致畸作用;菌株B1发酵上清液在离体叶片和活体植株上对番茄灰霉病具有良好的生防作用,其防治效果分别为68.80%和64.03%.根据形态特征、培养性状、生理生化特性和16S rDNA序列分析结果,将菌株B1初步鉴定为淡紫灰链霉菌Streptomyces lavendulae.通过正交试验筛选出菌株B1的液体发酵培养基组成为:葡萄糖15 g、玉米浆20g、NH4H2PO40.5 g、MgSO41.0 g、自来水1 000mL,pH 7.2～7.4.     

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。     

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.