Antimicrobial activity of crude extracts prepared from fungal mycelia

Objective: To evaluate the in vitro antimicrobial property of three different partitioned extracts(petroleum ether, ethanol and water) prepared from some fungal mycelia.Methods: Seven fungal mycelia were prepared, initially extracted with acidified ethanol(0.2 mol/L HCl in 80% ethanol), yielding the raw crude extracts. The obtained extracts were then further partitioned with petroleum ether(F1), ethanol(F2) and water(F3). All the fractions were tested for antimicrobial activity using the disc diffusion assay.Results: Our data showed that all the fractions could inhibit the testing bacteria.However, the inhibitory activity was found to be dependent on(i) the fungal strains used;(ii) the solvent extracted; and(iii) the testing bacteria assayed. In general, the ethanolic extracts(F2) derived from all fungi displayed highest inhibitory activity against the testing bacteria except for Chaetomium sp.Conclusions: The findings of the present study concluded that the extracts prepared from the fungal mycelia had the bioactive compounds with antibacterial property. This study is a pioneering work and further study should be carried out for development of the new drug leads.

Anti-fungal and anti-bacterial activities of ethanol extracts of selected traditional Chinese medicinal herbs

Objective:To evaluate in ritro antimicrobial activities of selected 58 ethno-medicinal plant extracts with a view to assess their therapeutic potential.Methods:A total of 58 traditional Chinese medicinal plants were carefully selected based on the literature review and their traditional use.The antimicrobial activities of ethanol extracts of these medicinal plants were tested against fungi(Aspergillus funigaius),yeast(Candida albicans),gram-negative(Acirelobacter haumannii and Pseudornnruis aeruginosa)and gram-positive bacteria(Staphglococcus aureus).The activities were tested at three different concentrations of 1.00,0.10 and 0.01 mg/mL.The data was analysed using Gene data Screener program.Results:The measured antimicrobial activities indicated that out of the 58 plant extracts,15 extracts showed anti-fungal activity and 23 extracts exhibited anti-bacterial activity.Eight plant extracts have exhibited both anti-bacterial and anti-fungal activities.For instance,Eucommia ulmoides,Pohgonum cuspidcrtum,Poria cocas and Uncaria rhineophylla showed activity against both bacterial and fungal strains,indicating their broad spectrum of activity.Conclusions:The results revealed that the ethanol extracts of 30 plants out of the selected 58 possess significant antimicrobial activities.It is interesting to note that the findings from the current study are consistent with the traditional use.A clear correlation has also been found between the antimicrobial activity and the flavonoid content of the plant extracts which is in agreement with the literature.Hence.the results presented here can be used to guide the selection of potential plant species for the isolation and structure elucidation of novel antimicrobial compounds in order to establish the structure-activity relationship.This in turn is expected to lead the way to the discovery of novel antimicrobial agents for therapeutic use.

Anti-dermatophytic activity of marine sponge,Sigmadocia carnosa(Dendy)on clinically isolated fungi

Objective:To screen the anti-fungal effects and find out the active metabolites from sponge, Sigmadocia carnosa(S.carnosa) against four dermatophytic fungi.Methods:The methanol,ethyl acetate and acetone extract of marine sponge,S.carnosa was examined against Trichaphyton mentagrophytes(T.mentagrophytes),Trichophyton rubrum(T.rubrum),Epidermophyton floccosum(E.floccosum) and Microsporum gypseum(M.gypseum) and qualitative analysed to find out the active molecules.Results:The methanol extract of sponge was expressed significant activity than ethyl acetate and acetone.The minimum inhibitory concentration(MIC) of methanol extract of sponge that resulted in complete growth inhibition of T.mentagrophytes,T.rubrum, E.floccosum and M.gypseum were found to 125,250,250 and 250 μg/mL respectively.But, 100%inhibition of fungal spore germination was observed in T.mentagrophytes at 500 μg/mL concentration followed by T.rubrum,E.floccosum and At.gypseum at 1000 μg/mL concentration. Other two extracts showed weak anti spore germination activity against the tested dermatophyte fungi.Methanol extracts showed presence of terpenoids,steroids,alkaloids,saponins and glycosides.Conclusion:Based on the literature,this is the first study which has conducted to inhibit the growth and spore germination of dermatophytic fungi with S.carnosa.Further research also needs to purify and characterize the secondary metabolites from the sponge,5.carnosa for the valuable source of novel substances for future drug discovery.

In-vitro Synthesis and Activity Identification of Antimicrobial Peptide from Aspergillus granifolium

[Objectives] This study was conducted to investigate the control effect of antimicrobial peptides to peanut aflatoxin contamination and achieve the purpose of biological control of peanut aflatoxin.[Methods]Bioinformatics methods were applied to screen antimicrobial peptides with strong antifungal activity in the antimicrobial peptide database and analyze their secondary structures and bacteriostatic characteristics,and the candidated peptide was then artificially synthesized,expressed and purified and detected for in-vitro activity.[Results] The antimicrobial peptide(AFP1) which was screened from Aspergillus granifolium exhibited strong antimicrobial activity against Aspergillus flavus.The inhibition rate of crude AFP1 at 3 mg/ml reached 58% for gram-positive bacteria,52% for gram-negative bacteria,and 62% for A.flavus.[Conclusions]This study provides a new approach for the prevention and control of various plant diseases including peanut disease,and a new idea for the biological prevention and control of plant diseases.

Development and evaluation of a herbal formulation with antipathogenic activities and probiotics stimulatory effects

Searching alternative feed antibiotics is always a study hotspot in the field of animal production. In this study, the antipathogenic activities and probiotics stimulatory effects of 30 kinds of herbs were screened through Oxford cup method and Hungate roll method. 15 herbs showed significantly antibacterial activities（P〈0.05） against Escherichia coli, Salmonella enteritidis, Salmonella typhimurium and Staphylococcus aureus. Seven herbs showed greatly stimulatory promoting effects on Lactobacillus acidophilus and Bifidobacterium longum. Finally, five herbs were combined for the developed formulation with selective antibacterial properties and they were Mume Fructus（35%）, Isatidis Folium（25%）, Moslae Herba（20%）, Chrysanthemi Indici Flos（13%） and Bupleuri Radix（7%）. The herbal formulation showed significantly antibacterial abilities against four pathogens and stimulatory promoting abilities on two probiotics in vitro and the equivalent activities in broiler chickens in vivo against E. coli and L. acidophilus. The toxicity study showed it had no toxicity, which indicated that it would be a kind of preferred candidate for an alternative antibiotic in future animal production.

Construction of a Constitutively Activated Gα Mutant in the Maize Pathogen <i>Cochliobolus heterostrophus</i>

Conserved eukaryotic signaling proteins participate in development and disease in plant pathogenic fungi. Mutants in CGA1, a heterotrimeric G protein Ga subunit gene of the maize pathogen Cochliobolus heterostrophus, are defective in several developmental pathways. Conidia from CGA1 mutants germinate as abnormal, straight-growing germ tubes that form few appressoria, and the mutants are female-sterile. The CGA1, Gα subunit, is also thought to act as a down regulator of hydrophobin expression and secretion in this fungus and in related Ascomycete species. Although cga1 mutants can cause normal lesions on plants there are host physiology conditions under which full virulence requires signal transduction through CGA1-mediated pathways. A Gα activated mutant, cga1Q204L was created to help establish the role of CGA1 in growth and development, and in mediating hydrophobin secretion and expression. The activated Gα allele was transformed into a cga1 mutant strain. The transgenic lines showed phenotypes resembling the null mutant in development, sporulation and hydrophobicity, indicating a possible role for CGA1 as a stabilizer of these traits.

复合木霉制剂防治黄连根腐病及其机理研究

为评价复合木霉制剂对黄连根腐病的防治效果,并揭示其防病机理,为黄连根腐病专用微生物农药的研发奠定基础,本试验将深绿木霉Trichoderma atroviride、长枝木霉T.longibrachiatum、钩状木霉T.hamatum、拟康宁木霉T.koningiopsis等4种木霉配制的复合制剂和尖镰孢Fusarium oxysporum以不同的方式分别施用于黄连,统计根腐病发生情况,检测黄连根部防御酶活性,用高通量测序分析根际土壤真菌群落结构。结果表明,复合木霉制剂对尖镰孢导致的根腐病具有明显预防效果;复合木霉制剂和尖镰孢分别接种黄连可提高SOD、POD、CAT、PAL、PPO等防御性酶活性,产生诱导抗性;而它们先后接种黄连可产生强化效应,从另一个途径提高植株抗病性。复合木霉制剂和尖镰孢都会降低真菌的数量、多样性,和某些真菌的相对丰度,而复合木霉制剂的抑菌作用更强烈,尤其能明显抑制尖镰孢、Ilyonectria sp.等病原真菌的生长,且能改善土壤真菌群落结构。木霉和尖镰孢都能在土壤中较长期定殖。可见,复合木霉制剂可以预防尖镰孢导致的黄连根腐病,防病机理包括诱导黄连植株产生抗性,接种后再遭受病原菌侵染产生的强化效应,优化土壤真菌群落结构,抑制土壤中病原菌等,且有效期较长。因此复合木霉制剂具有开发为微生物农药防治黄连根腐病的潜力。

覆膜对陇东旱地苹果根际土壤化感物质积累与真菌群落特征的影响

【目的】探究果园地膜覆盖对土壤化感物质及真菌群落的影响。【方法】以红富士苹果为研究对象,采用高效液相色谱技术和Illumina高通量测序技术探究了清耕(CK)、覆膜2年(2Y)、覆膜4年(4Y)和覆膜6年(6Y)对苹果树根际0~20 cm和>20~40 cm土层土壤理化性质、化感物质和真菌群落特征的影响。【结果】苹果根际土壤脲酶活性随着覆膜年限的延长而降低。土壤中主要的化感物质的含量总体上随着覆膜年限的延长呈现出降低的趋势。覆膜措施对苹果根际土壤中真菌群落特征具有显著的影响。土壤真菌群落的多样性随着覆膜年限的延长而增高,其中镰刀菌属丰度显著增加。综合对比,覆膜4年的苹果根际土壤中含水量及有机碳、微生物量碳、全氮含量显著增加,较CK分别增加了5.65%~15.00%、3.72%~8.29%、50.16%~64.31%和14.19%~31.44%。β-1,4-木糖苷酶、β-1,4-葡萄糖苷酶和纤维二糖水解酶的活性显著提高,较CK分别增高了78.71%~84.4%、89.01%~97.43%和83.45%~87.68%。并且在0~20 cm的土层中苹果根系的生长量显著提高。与CK相比,根系生物量、根表面积和根体积分别增加了489.84%、533.87%和542.39%。相关性分析结果表明,土壤脲酶、β-1,4-葡萄糖苷酶和香兰素是影响土壤真菌群落的主要环境因子。【结论】覆盖地膜可通过影响苹果根际土壤酶活性和微生物代谢活性,促进土壤碳循环,效果随覆膜年限而异,以覆膜4 a(年)最佳。同时覆膜年限的延长抑制了土壤中植物化感物质的积累,但覆盖年限过长会对土壤真菌群落结构产生不利的影响,因此在生产中,覆膜4 a为西北旱地苹果园适宜的连续覆膜年限。

猕猴桃根腐病根际土壤酶活性及真菌群落组成研究

分析猕猴桃根腐病感病植株和未感病植株根际土壤真菌群落差异,可为研究猕猴桃根腐病发生机制及其调控技术提供依据。在浙江省天台县街头镇的“红阳”猕猴桃种植基地,以树龄9年的猕猴桃根腐病感病植株和未感病植株根际土壤真菌为研究对象,对菌群ITS序列进行高通量测序注释后,对比分析了真菌群落结构与多样性指数的差异,并测定分析了根际土壤脲酶、蔗糖酶和酸性磷酸酶的活性。结果表明,猕猴桃根腐病的发生极显著地降低了根际土壤脲酶、蔗糖酶和磷酸酶的活性(p<0.01)。感病植株根际土壤真菌群落丰富度指数(Chao1)显著低于未感病植株根际土壤(p<0.05)。在门分类水平上,感病植株根际土壤真菌中相对丰度降低的有担子菌门、未分类真菌和接合菌门,其差异均为极显著(p<0.01);相对丰度升高的为子囊菌门,其差异达极显著水平(p<0.01)。在属分类水平上,感病植株根际土壤真菌相对丰度增加的有赤霉菌属、丛赤壳属、镰刀菌属、假裸囊菌属和肉座菌属,其差异均达极显著水平(p<0.01);相对丰度降低的有未分类伞菌纲、枝鼻菌属、粗糙孔菌属、线虫草属、支顶孢属、粪盘菌属、木霉属和被孢霉属,其差异均达极显著水平(p<0.01)。猕猴桃感染根腐病后,根际土壤真菌在门和属水平上的菌群变化打破了原有的微生物拮抗平衡关系。

凋落物真菌Neocucurbitaria salicis-albae及其代谢产物的抗细菌活性

研究旨在森林凋落物中获得具有抗菌活性的真菌资源,筛选并鉴定具有抗菌活性的真菌,纯化及鉴定其产生的抗菌化合物。以大兴安岭森林凋落物为试材,用颗粒法从中分离真菌,用基因序列比对分析测得分类学数据,用打孔药剂扩散法测得抗菌活性,采用柱层析法分离单体化合物,通过波谱分析法测得化学结构。分离得到真菌SGSF801,经多序列分析将其鉴定为Neocucurbitaria salicis-albae新株系。抗菌试验结果表明大米发酵产物对植物病原菌青枯劳尔氏菌、丁香假单胞杆菌及立枯丝核菌的抗菌活性较强。将真菌大米发酵产物分离纯化,得到一个单体化合物,通过1 H-NMR和13C-NMR将其鉴定为尾孢酰胺,分子式为C_(16)H_(13)NO_(7)。其对青枯劳尔氏菌的MIC值为31.25~62.5μg/mL,对丁香假单胞菌的MIC值为125~250μg/mL。本研究首次在Neocucurbitaria属真菌中分离得到尾孢酰胺,并且发现其具有抗植物病原细菌的活性,为凋落物真菌资源的进一步利用提供依据。

植物药组方MYF-20的抗马拉色菌活性及初步作用机制探究

目的以糠秕马拉色菌(Malassezia furfur)为目标菌株,对本实验室研发的植物药组方MYF-20的乙醇提取物进行抗菌活性及初步作用机制研究。方法采用改良CLSI-M27A法确定组方对马拉色菌的最小抑菌浓度,电导率法以及扫描电镜形态学观察研究MYF-20对马拉色菌细胞完整性的影响,铜皂法检测组方对马拉色菌脂肪酶活性影响,构建大蜡螟感染模型评价MYF-20的体内药效。结果MYF-20对马拉色菌的最小抑菌浓度为7.83 mg/mL(生药干重),MYF-20处理后,菌液相对电导率显著上升(P<0.01);扫描电镜证实了菌体芽孢断裂、细胞破裂内陷的发生;脂肪酶活性被显著抑制(P<0.01)。大蜡螟体内实验证明,MYF-20可以显著提高大蜡螟马拉色菌感染模型的存活率与黑化健康评分,降低体内真菌负荷(P<0.01)。结论MYF-20对马拉色菌在体内外均具有强抗菌活性,可通过多途径发挥其抑菌功能,具有成为抗马拉色菌植物类新药的一定潜力。

双季稻复种冬季马铃薯提高真菌α多样性和腐生真菌相对丰度促进秸秆腐解

【目的】秸秆还田是提高土壤肥力和作物产量的有效途径,复种模式影响土壤真菌群落结构和功能,进而影响秸秆在土壤中的降解程度。通过研究不同复种模式下秸秆的降解特征,为提高秸秆还田效益提供依据。【方法】培养试验的土壤取自3个三熟复种地块:稻—稻—紫云英(RRA)、稻—稻—油菜(RRO)、稻—稻—马铃薯(RRP),和两个两熟复种地块:稻—稻—冬板田(RRN)、稻—稻—冬泡田(RRI),采集时间均为早稻扬花期。每个土壤均设不添加和添加秸秆(0.5 g秸秆与80 g风干土混合)两个处理,然后置于250 mL棕色瓶中厌氧培养120天。在培养期内,定期取样检测CO_(2)排放量,破坏性采集土样测定土壤微生物生物量碳、氮含量和4种秸秆降解酶活性,利用扩增子高通量测序技术分析真菌群落结构。【结果】与两熟复种模式相比,三熟复种模式提高了土壤微生物生物量碳、氮含量以及β-葡萄糖苷酶、β-纤维二糖苷酶、β-木糖苷酶和漆酶活性。三熟与两熟复种土壤之间真菌群落结构存在差异,RRP地块土壤真菌ASV数目、Chao1、ACE和Shannon指数,以及分解半纤维素、纤维素和木质素等有机物质的无茎真菌属(Acaulium)、被孢霉属(Mortierella)、粉枝孢属(Oidiodendron)的相对含量显著高于两熟地块。共现性网络分析发现,与RRN相比,RRO和RRP复种模式增加了土壤真菌网络的复杂性,提高了网络中子囊菌门、壶菌门等具有秸秆分解潜力的关键物种的数量。冗余分析及回归分析等发现,全磷是复种系统中影响土壤真菌群落结构及秸秆降解酶类活性的最重要的环境因子。【结论】相比于冬闲两熟复种模式,三熟复种模式可增加微生物生物量,提高秸秆降解酶活性,同时提高真菌α多样性以及增加腐生真菌的相对丰度,进而更有效地促进秸秆的分解。双季稻结合冬季复种马铃薯是促进还田秸秆腐解、提升土壤肥力的有效复种模式。

利用植物病原真菌除草的研究进展

杂草对农业生产危害巨大,长期使用化学除草剂带来诸多问题,促使新型环保高效除草剂的开发需求迫切。植物病原真菌源除草剂是利用活体真菌或其代谢产物开发的生物除草剂,具有资源丰富、低毒性、环境污染小等优点,成为新型除草剂开发的重要资源。文章总结了具有除草活性的植物病原真菌及其代谢产物的种类,综述了利用植物病原真菌除草机理及应用现状,并对未来植物病原真菌源除草剂的发展进行了展望。

裂解多糖单加氧酶在植物病害中的研究进展

植物病原真菌在侵染植物的过程中会分泌细胞壁降解酶来破坏植物细胞壁,以达到成功入侵寄主的目的。研究表明,病原菌分泌的细胞壁降解酶中的纤维素酶、果胶酶、木聚糖酶、几丁质酶、酯酶均参与了植物细胞壁的降解和病原菌致病的过程,但是对于细胞壁降解酶中的裂解多糖单加氧酶在病原菌侵染植物过程中的功能研究较少。根据近年来辅助活性酶类以及属于辅助活性酶类中的裂解多糖单加氧酶的研究进展,综述了辅助活性酶的分布、种类、功能以及裂解多糖单加氧酶植物病害中的作用研究,旨在为辅助活性酶类在植物病害中的功能研究和病害防控提供参考和依据。

祁连山南坡不同海拔高度土壤真菌群落结构特征

土壤真菌在森林生态系统的养分循环和能量流动方面发挥着重要作用,为探究海拔高度对土壤理化性质和酶活性的影响,揭示土壤真菌群落的海拔分布格局,以青海北山林场5个海拔高度(2400、2500、2600、2700、2800 m)表层土壤为研究对象,采用高通量测序技术分析真菌群落的多样性和丰富度,探讨土壤真菌群落结构组成的主要影响因素。结果表明,5个海拔高度土壤真菌共有15门59纲144目302科633属。在门分类上,主要的优势真菌群落有子囊菌门、担子菌门以及被孢霉门。土壤真菌群落丰富度指数(Ace、Chao指数)和多样性指数(Shannon指数)总体上随着海拔的上升呈增大的趋势;土壤有机碳含量、含水率和α-葡萄糖苷酶活性随着海拔的上升呈升高的趋势,脲酶活性随着海拔的升高先下降再升高再下降。冗余分析表明,土壤理化性质和酶活性共同解释了真菌群落变异的81.23%,土壤硝态氮含量、全磷含量和pH值是土壤真菌群落丰富度差异的主要影响因素。

真菌漆酶的酶活测定方法评价

目前真菌漆酶酶活的测定方法多样,没有统一的标准,致使不同研究之间的漆酶酶活无法进行比较分析,也造成漆酶产品在酶活质量意义上的混乱。因此,对测定真菌漆酶酶活的各种不同的分光光度法进行了综述和比较分析,认为采用ABTS法作为测定漆酶酶活的方法较具合理性和科学性,建议作为漆酶酶活测定的统一方法。

一株抑制油菜核盘菌菌核形成的解淀粉芽孢杆菌

检测了从不同土壤中分离的17株芽孢杆菌对油菜核盘菌的抑制效果,发现4株菌株具有不同程度的抑制菌丝生长的能力,其中地衣芽孢杆菌菌株AJH-1和解淀粉芽孢杆菌菌株CH-2的抑菌效果最好.CH-2菌株不仅能抑制菌丝的生长,而且能抑制菌核的形成.CH-2菌株培养液经硫酸铵沉淀后具有抑制核盘菌生长的效果,且稀释10倍后仍具有抗菌活性.初步认为CH-2菌株的抑菌活性可能是抗菌蛋白或多肽的作用.

新疆两种野生葱浸提液对几种植物病原真菌的抑制作用

新疆野生葱属植物资源十分丰富 ,本文就其中两个具有浓烈辛辣气味的种———长喙葱和滩地韭的组织浸提液对棉花、番茄等主要作物病害病原真菌生长的抑制特性进行了研究。试验结果显示 :长喙葱浸提液对镰孢菌、轮枝菌、丝核菌及疫霉菌的生长具有明显抑制效果 ;其1 0、2 0和 50倍稀释液对丝核菌 1 2h的抑菌率分别为 1 0 0 %、94%、80 % ;而其 1 0、2 0倍稀释液对镰孢菌 1 2h的抑菌率分别为 1 0 0 %、72 .2 %。滩地韭浸提液能抑制镰孢菌、轮枝菌的生长 ,但不影响丝核菌的生长。两类浸提液的抑菌效果均受温度影响 ,并随稀释倍数和作用时间的增加而减弱。长喙葱浸提液在 4℃冷藏室内放置 1 0d和在 1 2 1℃条件下放置 30min都会丧失其抑菌活力。而滩地韭浸提液经 1 0 0℃水浴锅处理 5min后其抑菌活力仍可保持 2周之久。长喙葱浸提液经透析去除小分子化合物后 ,其上清液、沉淀都无抑菌作用 。

孜然化学成分及其生物活性研究进展

本文综述了孜然在化学成分、医疗、食品、农业等方面的研究进展,着重阐述了其在杀虫、抑菌方面的研究概况,以期为孜然在植物源农药方面的研究和综合开发应用提供依据.

白屈菜中白屈菜红碱的提取及抑菌活性

对白屈菜中白屈菜红碱的含量和提取工艺进行研究,通过单因素试验和正交试验确定超声波法辅助提取最佳工艺:以60%乙醇作为溶剂,料液比1:20(g/ml),在超声波功率为700W的条件下超声波辅助提取35min。白屈菜红碱提取物对甜瓜枯萎病菌、西瓜枯萎病菌、茄子黄萎病菌、黄瓜枯萎病菌、辣椒炭疽病菌、葡萄炭疽病菌、草莓灰霉病菌、番茄灰霉病菌和西葫芦菌核病菌等植物病原真菌菌丝的生长均具一定抑制作用。