木霉peptaibols抗菌肽的研究进展

Peptaibols是一类由非核糖体肽合成酶(NRPSs)合成的富含α-氨基异丁酸(Aib)的特殊抗菌肽.目前发现的317种peptaibols大多由木霉属真菌产生.本文对木霉产生的这类特殊抗菌肽-peptaibols的多样性、发酵、分离纯化、鉴定及其生物合成进行了综述.     

多杀菌素的生物合成

多杀菌素是一种新颖大环内酯类杀虫剂,具有对害虫高效、对环境安全、对哺乳动物低毒的优异特点。介绍了多杀菌素生物合成的步骤,及参与这些合成步骤的有关酶系统和基因簇。通过对刺糖多孢菌中多杀菌素合成基因的克隆鉴定与分析,已基本了解多杀菌素生物合成的限速步骤及相关控制基因,从而可通过遗传工程的办法改造刺糖多孢菌,提高多杀菌素的产量 。     

木霉分子生物学研究进展

木霉Ｔｒｉｃｈｏｄｅｒｍａ ｓｐｐ．是普遍存在并具有重要经济意义的一类真菌。本文度从木霉大分子;基因克隆;转化系统;外源基因表达;在工农业生产中的应用等方面对木霉分子生物学研究进展进行综述。     

木霉和粘帚霉的生物防治研究进展

化学农药的大量使用,严重破坏农业生态系统,并对环境造成污染。而生物防治制剂可以克服这些问题,具有广阔的应用前景。目前已发现不少微生物具有生物防治作用。木霉（Trichoderma）和粘帚霉（Gliocladium）是其中一类可抑制土传植物病原菌的真菌,其作用机理主要是：抗菌、溶解、竞争、寄生和促进植物的生长[1].迄今为止,有关木霉和粘帚霉在生物防治方面的研究已开展近60年。早在1932年,Weindling观察到木素木霉（T.lignorum）和立枯丝核菌（Rhizoctoniasolani）同时培养时,木素木霉的菌丝缠绕着立枯丝核菌的菌丝,使其菌丝原生质凝…     

木霉属7个中国新记录种（英文）

报道木霉属7个中国新记录种:厚木霉、地中海木霉、矩孢木霉、近渐绿木霉、多孢木霉、特里克木霉和渐绿木霉。厚木霉分离自上海;地中海木霉、矩孢木霉、多孢木霉和特里克木霉分离自新疆;近渐绿木霉和渐绿木霉分离自四川;结合ITS、tef1-α和形态学特征进行鉴定。     

茁霉多糖生物合成的研究进展

本文综述了茁霉多糖的生物合成,简单探讨了其生物合成的机理,并从发酵工艺入手,对通过各种发酵条件的对比,分析并讨论了生物合成的一系列优化结果。同时,简要介绍了茁霉多糖的一些理化性质以及它在工业上的生产应用,并讨论了其应用前景。     

木霉属2个中国新记录种

【背景】木霉菌现存的Stromaticum进化支为Samuels等2012年定义,包括9个木霉种;国内目前仅报道子座木霉(Trichoderma stromaticum)、蠕状毛木霉(T.vermipilum)和絮状木霉(T.floccosum)3个种。【目的】报道2个木霉属中国新记录种。【方法】采用THSM选择性培养基,从北京和山东两地土壤中分离木霉菌株,通过形态学特征、TEF1-α和RPB2序列对菌株进行鉴定。【结果】通过对TEF1-α和RPB2的系统发育分析,2个菌株分别与T.ivoriense(科特迪瓦木霉)和T.barbatum(毛簇木霉)相近;且形态学特征上存在差异。综合鉴定2个菌株分别为科特迪瓦木霉(T.ivoriense)和毛簇木霉(T.barbatum)或其近缘种。【结论】在国内新发现科特迪瓦木霉(T.ivoriense)和毛簇木霉(T.barbatum)两个木霉种,它们属于Stromaticum进化支,该进化支国内木霉种类增加到5个。     

木霉现有种类名录

木霉因其在酶、抗生素及生防等方面有着重要的经济生产价值而得到世界广泛的研究和关注。截止目前,已报道木霉种类达到212种,准确对其进行分类和鉴定对于木霉的研究和利用有着重要的意义。本文整理了目前已报道的木霉种类名录及用于木霉系统发育种类鉴定的分子技术和工具,这些技术和工具为木霉研究者对木霉进行准确种类鉴定提供技术指导和帮助。     

木霉属真菌的系统学及其应用研究

介绍了木霉属真菌的分类系统 ,有关木霉种系发育的分子生物学研究进展 ,以及在酶制剂、农业和环境保护中的应用概况。     

Bioengineered silver nanoparticles using Curvularia pallescens and its fungicidal activity against Cladosporium fulvum

Microorganisms based biosynthesis of nanomaterials has triggered significant attention, due to their great potential as vast source of the production of biocompatible nanoparticles (NPs). Such biosynthesized functional nanomaterials can be used for various biomedical applications. The present study investigates the green synthesis of silver nanoparticles (Ag NPs) using the fungus Curvularia pallescens (C. pallescens) which is isolated from cereals. The C. pallescens cell filtrate was used for the reduction of AgNO₃ to Ag NPs. To the best of our knowledge C. pallescens is utilized first time for the preparation of Ag NPs. Several alkaloids and proteins present in the phytopathogenic fungus C. pallescens were mainly responsible for the formation of highly crystalline Ag NPs. The as-synthesized Ag NPs were characterized by using UV–Visible spectroscopy, X-ray diffraction and transmission electron microscopy (TEM). The TEM micrographs have revealed that spherical shaped Ag NPs with polydisperse in size were obtained. These results have clearly suggested that the biomolecules secreted by C. pallescens are mainly responsible for the formation and stabilization of nanoparticles. Furthermore, the antifungal activity of the as-prepared Ag NPs was tested against Cladosporium fulvum, which is the major cause of a serious plant disease, known as tomato leaf mold. The synthesized Ag NPs displayed excellent fungicidal activity against the tested fungal pathogen. The extreme zone of reduction occurred at 50 μL, whereas, an increase in the reduction activity is observed with increasing the concentration of Ag NPs. These encouraging results can be further exploited by employing the as synthesized Ag NPs against various pathogenic fungi in order to ascertain their spectrum of fungicidal activity.     

The synthesis of chitosan-based silver nanoparticles and their antibacterial activity

Chitosan-based silver nanoparticles were synthesized by reducing silver nitrate salts with nontoxic and biodegradable chitosan. The silver nanoparticles thus obtained showed highly potent antibacterial activity toward both Gram-positive and Gram-negative bacteria, comparable with the highly active precursor silver salts. Silver-impregnated chitosan films were formed from the starting materials composed of silver nitrate and chitosan via thermal treatment. Compared with pure chitosan films, chitosan films with silver showed both fast and long-lasting antibacterial effectiveness against Escherichia coli. The silver antibacterial materials prepared in our present system are promising candidates for a wide range of biomedical and general applications.     

Phytosynthesis of silver nanoparticles using Mangifera indica flower extract as bioreductant and their broad-spectrum antibacterial activity

The present study focused on the evaluation of antibacterial property of silver nanoparticles (AgNPs) synthesized using mango flower extract. The morphology of the synthesized AgNPs was observed under transmission electron microscopy and the particles have shown spherical shape in the range of 10–20 nm. X-ray powder diffraction analysis confirmed the crystalline nature of the AgNPs. The atomic percentage of the Ag element in the nanoparticles was about 7.58% which is greater than the other elements present in the sample. The AgNPs showed extensive lethal effect on both Gram-positive (Staphylococcus sp.) and Gram-negative (Klebsiella sp., Pantoea agglomerans, and Rahnella sp.) bacteria. The extensive lethal effect of AgNPs against clinically important pathogens demonstrated that the mango flower mediated AgNPs could be applied as potential antibacterial agent to control the bacterial population in the respective industries.     

靶向α-酮戊二酸脱氢酶增强纳米银的抗菌作用

【目的】纳米银(silver nanoparticles, AgNPs)的生物安全性一直受业界诟病,扩大纳米银的治疗窗将为治疗人和动物多耐药性细菌感染提供有效的备选药物。本研究拟用三羧酸循环的重要成员α-酮戊二酸(alpha-ketoglutaric acid, AKG)对纳米银进行表面修饰以提高其抗菌的生物安全性。【方法】芦丁在常温下合成纳米银,用全波长分光光度计、粒度仪及透射电镜进行表征。加1 mmol/L聚乙烯吡咯烷酮(polyvinylpyrrolidone, PVP)作为稳定剂(PVP-AgNPs),另加10 mmol/L AKG作为封端剂(PVP-AgNPs@AKG),比较2种纳米银的抗菌性及对人正常宫颈上皮细胞(human cervical epithelial cells, HCerEpic)的毒性作用,再分析2种纳米银对大肠杆菌(Escherichia coli) BW25113能量代谢、抗氧化应激和无氧呼吸相关基因表达等的影响。【结果】PVP-AgNPs@AKG对多株革兰阳性细菌和革兰阴性细菌的最小抑菌浓度(minimal inhibit concentration, MIC)和最低杀菌浓度(minimum bactericidal concentration, MBC)均比PVP-AgNPs低50%或50%以上,而对HCerEpic细胞的毒性无显著差异。与PVP-AgNPs相比,PVP-AgNPs@AKG在MIC浓度下对E. coli α-酮戊二酸脱氢酶活性的抑制作用增强,AKG蓄积,ATP水平显著降低,同时活性氧(reactive oxygen species, ROS)的水平显著升高,soxS表达上调,但是,厌氧呼吸相关的arcA、fnr、fdnH基因表达上调的程度显著降低。【结论】AKG修饰纳米银能通过靶向α-酮戊二酸脱氢酶抑制细菌的能量代谢,使其对氧化损伤更敏感,从而获得更强的抗菌能力,是一种扩大纳米银治疗窗的有效手段。     

Alleviation of abiotic salt stress in Ochradenus baccatus (Del.) by Trichoderma hamatum (Bonord.) Bainier

The current study was taken up to examine the role of bioagent (Trichoderma hamatum) in mitigating the deleterious effects of NaCl stress in Ochradenus baccatus. Varying concentrations of salt (0, 75, and 150 mM) were used to observe the effect on growth, pigments, some key metabolic attributes, antioxidant enzymes, and elemental accumulation in O. baccatus. The results indicated significant decrease in seed germination, plant growth, pigment content, membrane stability index, tissue water content, and total lipid content with salt stress. Lipid peroxidation increases with the increasing concentration of NaCl. Moreover, salinity stimulated the biosynthesis of phenols, diacylglycerol, sterol esters, nonesterified fatty acids, and enzymatic antioxidants like superoxide dismutase, catalase, peroxidase, ascorbate peroxidase, glutathione reductase. The Na⁺ content in shoot increases with elevated levels of NaCl concentration, accompanied with significant decreases in K⁺, Mg²⁺, and Ca²⁺. Application of bioagent (T. hamatum) has been observed to alleviate the antagonistic effect of salt stress on plant growth and metabolic processes. In absence and presence of salt stress, the bioagent stimulated the plant growth and alter the plant metabolism through the modification of the above parameters.     

Biosynthesis of silver and gold nanoparticles using thermophilic bacterium Geobacillus stearothermophilus

Nanomaterials have assumed a great deal of importance as they often display unique and considerably modified physical, chemical and biological properties as compared to their counterparts of the macroscale. In this study, biogenic synthesis of silver and gold nanoparticles by Geobacillus stearothermophilus has been attempted. The exposure of G. stearothermophilus cell free extract to the metal salts leads to the formation of stable silver and gold nanoparticles in the solution. These nanoparticles were characterized by UV–Vis spectra, FTIR, TEM, and XRD. The silver and gold nanoparticles have absorption maxima at 423 nm and 522 nm respectively. The TEM micrograph revealed the formation of polydispersed particles in the case of silver nanoparticles and monodispersed particles with respect to the gold nanoparticles. High stability of the nanoparticle solution could be attributed to the secretion of certain capping proteins by the bacterium in the reaction mixture. The involvement of these proteins was confirmed by FTIR and SDS PAGE.     

Biosynthesis and antibacterial activity of ZnO nanoparticles using Trifolium pratense flower extract

Zinc oxide (ZnO) has broad applications in various areas. Nanoparticle synthesis using plants is an alternative to conventional physical and chemical methods. It is known that the biological synthesis of nanoparticles is gaining importance due to its simplicity, eco-friendliness and extensive antimicrobial activity. Also, in this study we report the synthesis of ZnO nanoparticles using Trifolium pratense flower extract. The prepared ZnO nanoparticles have been characterized by UV–Vis absorption spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM) with Energy dispersive X-ray analysis (EDX). Besides, this study determines the antimicrobial efficacy of the synthesized ZnO nanoparticles against clinical and standard strains of S. aureus and P. aeruginosa and standard strain of E. coli.     

Synthesis of silver nanoparticles by Bacillus clausii and computational profiling of nitrate reductase enzyme involved in production

Biogenic synthesis of silver nanoparticles using microorganisms has found interest recently since last decade because of their prospect to synthesize nanoparticles of various size, shape and morphology which are eco-friendly. Here, an eco-friendly method for production of silver nanoparticles from Bacillus clausii cultured from Enterogermina is explored. Along with the biosynthesis and conformity test, in silico studies was done on NADPH dependent nitrate reductase enzymes from the view point of designing a rational enzymatic strategy for the synthesis. The detailed characterization of the nanoparticles was carried out using UV-Vis spectroscopy, Dynamic Light Scattering (DLS) particle size analysis, Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD) analysis. Computational profiling and in silico characterization of NADH dependent enzymes was carried out based on literature and work done so far. Nitrate reductase sequence was retrieved from NCBI for characterization. Secondary structure was evaluated and verified by JPred as well as SOPMA Tool. Tertiary structure was also modeled by MODELLER and ITASSER parallel and the best structure was selected based on energy values. Structure validation was done by GROMACS and RMSD, RMSF, temperature variation plot were also plotted. Interactions graphs between nitrate reductase and ligand silver nitrate was done through molecular docking using Hex.     

木霉菌合成银纳米粒子条件的优化及其对甜瓜尖孢镰刀菌抑制作用

随着绿色环保观念的普及,生物合成金属纳米粒子的方法备受青睐。纳米银(Silver nanoparticles,AgNPs)由于其抗菌活性强且不易产生抗药性等特点在农业病害防治中越来越受到关注。文中利用橘绿木霉Trichoderma citrinoviride和毛簇木霉Trichoderma velutinous研究了AgNPs的最适合成条件和AgNPs对尖孢镰刀菌抑菌活性。结果表明,所有合成的AgNPs均在400–500 nm处有吸收峰,两种木霉生物合成AgNPs的最适合成条件为CL法(菌丝滤液)静置光照培养,底物AgNO₃浓度为2.0mmol/L,pH值为7,反应温度为45℃。橘绿木霉和毛簇木霉合成的AgNPs均对尖孢镰刀菌有抑制作用,抑菌效果随浓度的增加而增大,AgNPs在浓度为200 mg/L时,抑菌率分别达到33.745%和36.083%。     

Green synthesis of silver nanoparticles using Citrus limon peels and evaluation of their antibacterial and cytotoxic properties

The present work aimed to synthesis silver nanoparticles (AgNPs) using biological waste products Citrus limon peels, its characterization, antimicrobial activities and the cytotoxic effect of the synthesized green AgNPs. Characterization of the prepared AgNPs showed the formation of spherical, and few agglomerated AgNPs forms as measured by UV–visible spectrophotometer. The average size of the prepared AgNPs was 59.74 nm as measured by DLS technique. The spectrum of the synthesized AgNPs was observed at 3 KeV using the EDX. On the other hand, FTIR analysis of the green synthesized AgNPs showed the presence of alcohols, phenolics, mono-substituted alkynes, aliphatic primary amines, sodium salt, amino acid, or SiOH alcohol groups. The antimicrobial studies of the formed AgNPs showed positive activity against most of the studied human pathogenic bacteria with varying degrees. Finally, the evaluation of the cytotoxic effect of the green synthesized AgNPs were done using two types of cell lines, human breast cancer cell line (MCF-7) and human colon carcinoma cell line (HCT-116). The results revealed the concentration has a direct correlation with cell viability. The 50% inhibitory concentration (IC₅₀) of MCF-7 cell line was in of 23.5 ± 0.97 µL/100 µL, whereas the HCT-116 cell line was in 37.48 ± 5.93 µL/100 µL.