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Mycelial Growth (mycelial + growth)
Terms modified by Mycelial Growth Selected AbstractsEffects of metals and pH on in vitro growth of Armillaria ostoyae and other root and butt rot fungi of red spruceFOREST PATHOLOGY, Issue 1 2001P. M. Wargo Armillaria ostoyae, Perenniporia subacida, Resinicium bicolor and Scytinostroma galactinum, root and butt rot fungi found on red spruce, Picea rubens, were tested, in vitro, for their sensitivity to metals typically found in high elevation forest soils where red spruce grows. Rhizomorph production by A. ostoyae from woody inocula in soils from red spruce stands at three elevations at each of five mountainous sites in the eastern United States was inhibited completely in the mineral soil from all elevations at all sites, and was also reduced significantly in the organic horizon from the upper two elevations at three of the sites. Inhibition was correlated with concentrations of metal ions in the soil. Growth of rhizomorphs into an agar medium containing lead and other heavy metals was inhibited for isolates of A. ostoyae from red spruce, but not for an isolate of Armillaria gallica from sugar maple; aluminium inhibited rhizomorph growth of isolates of both species. Mycelial growth of all four root and butt rot fungi was inhibited by lead, aluminium and other heavy metals depending on the solubility and concentration of metal and pH of the medium; growth inhibition was usually greater at an initial pH of 3.5 than at pH 4.5. Metal ions inhibited radial growth of Armillaria species more than that of the other three fungi. Rhizomorph growth of Armillaria was inhibited more than radial growth. Because local spread of A. ostoyae occurs frequently by means of rhizomorph growth between near roots, increases in lead, aluminium and other metals in the forest floor may contribute to this fungus' scarcity in high elevation soils and reduced incidence of infection at these sites in the eastern United States. [source] Characterization of the Mucor circinelloides life cycle by on-line image analysisJOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2003T.L. Lübbehüsen Abstract Aims: The life cycle of the dimorphic fungus Mucor circinelloides was studied in a temperature-controlled flow-through cell, which constitutes an ideal tool when following the development of individual cells, with a view to understanding the growth and differentiation processes occurring in and between the different morphological forms of the organism. Methods and Results: Mycelial growth and the transformation of hyphae into chains of arthrospores were characterized by image analysis techniques and described quantitatively. The influence of the nature (glucose and xylose) and concentration of the carbon source on specific growth rate and hyphal growth unit length were studied. The organism branched more profusely on xylose than on glucose while the specific growth rates determined were rather similar. Methods were developed to study the yeast-like growth phase of M. circinelloides in the flow-through cell, and combined with fluorescent microscopy which allowed new insights to bud formation. Additionally, numbers and distribution of nuclei in arthrospores, hyphae and yeasts were studied. Conclusions: The results give essential information on the morphological development of the organism. Significance and Impact of Study: Development of any industrial process utilizing this organism will be dependent on the information obtained here for effective process optimization. [source] Fungicide Effectiveness during the Various Developmental Stages of Peronophythora litchii In VitroJOURNAL OF PHYTOPATHOLOGY, Issue 7-8 2009Hancheng Wang Abstract Litchi downy blight caused by Peronophythora litchii is one of the most destructive diseases suffered by litchi in China. This study has evaluated the activities of the fungicides dimethomorph (DMM), azoxystrobin (AZB), famoxadone (FMD), metalaxyl (MTL), cymoxanil (CYX) and mancozeb (MCB) on the mycelial growth, sporulation, zoospores release, and germination of sporangia as well as of cystospores of P. litchii. Dimethomorph and MTL inhibited mycelial growth more effectively than the other fungicides tested. Mycelial growth was affected less by MCB, and only weakly by AZB, FMD and CYX. Sporangia production was more strongly reduced by DMM and MTL than by AZB, FMD, CYX or MCB. Zoospore release from the sporangia was most sensitive to AZB and FMD, less sensitive to MCB and insensitive to DMM, MTL and CYX. Direct germination of sporangia of P. litchii was the most strongly inhibited by AZB and FMD, followed by DMM and MCB, whilst the sensitivity of this life stage to MTL and CYX was relatively low. Germination of encysted zoospores of P. litchii was the most sensitive to AZB and FMD, followed by DMM. Mancozeb was moderately active, while MTL and CYX did not inhibit this development stage. This is the first report on the in vitro response of the litchi pathogen, P. litchii, to fungicides. These findings can be valuable tools in setting up efficient disease management programmes to control litchi downy blight. [source] Effects of tebuconazole on morphology, structure, cell wall components and trichothecene production of Fusarium culmorum in vitroPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 6 2001Zhensheng Kang Abstract The effects of tebuconazole, a systemic fungicide, on the morphology, structure, cell wall components and toxin production of Fusarium culmorum were investigated in vitro. Treatment was by application of four filter paper strips (0.75,cm,×,5.0,cm) soaked in 20,µg,ml,,1 fungicide placed around a point inoculum in Petri dishes. Mycelial growth was strongly inhibited by fungicide treatment. Scanning electron microscopic observations showed that the fungicide caused irregular swelling and excessive branching of hyphae. The morphological changes induced by the fungicide at the ultrastructural level included considerable thickening of the hyphal cell walls, excessive septation, the formation of the incomplete septa, extensive vacuolisation, accumulation of lipid bodies and progressing necrosis or degeneration of the hyphal cytoplasm. Non-membrane inclusion bodies were often detected in the hyphal cytoplasm. Furthermore, the formation of new hyphae (daughter hyphae) inside collapsed hyphal cells was common following treatment. The daughter hyphae also displayed severe alterations such as irregular thickening of the cell walls and necrosis of the cytoplasm. Using cytochemical techniques, the labelling densities of chitin and ,-1,3-glucan in the cell walls of the fungicide-treated hyphae were more pronounced than in those of the control hyphae. Moreover, immunogold labelling with antiserum against deoxynivalenol (DON) revealed that Fusarium toxin DON was localized in the cell walls, cytoplasm, mitochondria and vacuoles of the hyphae from the control and the fungicide treatment, but the labelling density in the fungicide-treated hyphae decreased dramatically compared with the control hyphae, indicating that tebuconazole reduced Fusarium toxin production of the fungus. © 2001 Society of Chemical Industry [source] Verticillium longisporum and V. dahliae: infection and disease in Brassica napusPLANT PATHOLOGY, Issue 1 2006L. Zhou Verticillium wilt of oilseed rape (Brassica napus) is caused primarily by Verticillium longisporum and has become a serious problem in northern Europe. In order to evaluate whether V. longisporum and V. dahliae differ in their interaction with oilseed rape, phenotypical and molecular assessments were made. Oilseed rape plants for fungal assessments were inoculated with V. longisporum and V. dahliae via root-dipping and samples were taken from roots, stems, leaves, flowers, pods and seeds during plant development. The infection by V. longisporum was found to start mainly in lateral roots and root-hairs, followed by colonization of the xylem vessels and extensive spread in stems and leaves, whereas V. dahliae infected the main roots and remained in the region below the cotyledon node of the plants. Re-isolation studies, together with PCR analysis of samples taken from early growth stages through to fully ripe plants, showed that the onset of flowering was a critical phase for V. longisporum to colonize plants. No seeds infected with V. longisporum were found. Mycelial growth from V. dahliae but not V. longisporum was significantly reduced on media containing tissue from a low glucosinolate B. napus genotype compared with growth on media containing tissue from a high glucosinolate cultivar. The results of this study suggest that V. longisporum favours B. napus as host and that the transition from the vegetative to the generative phase is of importance for the spread of the fungus in oilseed rape plants. [source] Limits of life in hostile environments: no barriers to biosphere function?ENVIRONMENTAL MICROBIOLOGY, Issue 12 2009Jim P. Williams Summary Environments that are hostile to life are characterized by reduced microbial activity which results in poor soil- and plant-health, low biomass and biodiversity, and feeble ecosystem development. Whereas the functional biosphere may primarily be constrained by water activity (aw) the mechanism(s) by which this occurs have not been fully elucidated. Remarkably we found that, for diverse species of xerophilic fungi at aw values of , 0.72, water activity per se did not limit cellular function. We provide evidence that chaotropic activity determined their biotic window, and obtained mycelial growth at water activities as low as 0.647 (below that recorded for any microbial species) by addition of compounds that reduced the net chaotropicity. Unexpectedly we found that some fungi grew optimally under chaotropic conditions, providing evidence for a previously uncharacterized class of extremophilic microbes. Further studies to elucidate the way in which solute activities interact to determine the limits of life may lead to enhanced biotechnological processes, and increased productivity of agricultural and natural ecosystems in arid and semiarid regions. [source] Volatile organic compounds: a potential direct long-distance mechanism for antagonistic action of Fusarium oxysporum strain MSA 35ENVIRONMENTAL MICROBIOLOGY, Issue 4 2009Daniela Minerdi Summary Fusarium oxysporum MSA 35 [wild-type (WT) strain] is an antagonistic Fusarium that lives in association with a consortium of bacteria belonging to the genera Serratia, Achromobacter, Bacillus and Stenotrophomonas in an Italian soil suppressive to Fusarium wilt. Typing experiments and virulence tests provided evidence that the F. oxysporum isolate when cured of the bacterial symbionts [the cured (CU) form], is pathogenic, causing wilt symptoms identical to those caused by F. oxysporum f. sp. lactucae. Here, we demonstrate that small volatile organic compounds (VOCs) emitted from the WT strain negatively influence the mycelial growth of different formae speciales of F. oxysporum. Furthermore, these VOCs repress gene expression of two putative virulence genes in F. oxysporum lactucae strain Fuslat10, a fungus against which the WT strain MSA 35 has antagonistic activity. The VOC profile of the WT and CU fungus shows different compositions. Sesquiterpenes, mainly caryophyllene, were present in the headspace only of WT MSA 35. No sesquiterpenes were found in the volatiles of ectosymbiotic Serratia sp. strain DM1 and Achromobacter sp. strain MM1. Bacterial volatiles had no effects on the growth of the different ff. spp. of F. oxysporum examined. Hyphae grown with VOC from WT F. oxysporum f. sp. lactucae strain MSA 35 were hydrophobic whereas those grown without VOCs were not, suggesting a correlation between the presence of volatiles in the atmosphere and the phenotype of the mycelium. This is the first report of VOC production by antagonistic F. oxysporum MSA 35 and their effects on pathogenic F. oxysporum. The results obtained in this work led us to propose a new potential direct long-distance mechanism for antagonism by F. oxysporum MSA 35 mediated by VOCs. Antagonism could be the consequence of both reduction of pathogen mycelial growth and inhibition of pathogen virulence gene expression. [source] Phenazines and biosurfactants interact in the biological control of soil-borne diseases caused by Pythium spp.ENVIRONMENTAL MICROBIOLOGY, Issue 3 2008Maaike Perneel Summary In this study, the putative role of phenazines and rhamnolipid-biosurfactants, antagonistic metabolites produced by Pseudomonas aeruginosa PNA1, was tested in the biological control of Pythium splendens on bean (Phaseolus vulgaris L) and Pythium myriotylum on cocoyam (Xanthosoma sagittifolium L Schott). A rhamnolipid-deficient and a phenazine-deficient mutant of PNA1 were used either separately or jointly in plant experiments. When the mutants were applied separately, no disease-suppressive effect was observed, although both mutants still produced one of the antagonistic compounds (phenazines or rhamnolipids). When the mutants were concurrently introduced in the soil, the biocontrol activity was restored to wild-type levels. Bean seeds developed significantly less pre-emergence damping-off caused by P. splendens when treated with a mixture of purified phenazine-1-carboxamide and rhamnolipids than with any of the chemicals alone. When phenazines and rhamnolipids were combined at concentrations that had no observable effects when the metabolites were applied separately, mycelial growth of P. myriotylum was significantly reduced. In addition, microscopic analysis revealed substantial vacuolization and disintegration of Pythium hyphae after incubation in liquid medium amended with both metabolites. Results of this study indicate that phenazines and biosurfactants are acting synergistically in the control of Pythium spp. [source] Aspergillus oryzae in solid-state and submerged fermentationsFEMS YEAST RESEARCH, Issue 2 2002Progress report on a multi-disciplinary project Abstract We report the progress of a multi-disciplinary research project on solid-state fermentation (SSF) of the filamentous fungus Aspergillus oryzae. The molecular and physiological aspects of the fungus in submerged fermentation (SmF) and SSF are compared and we observe a number of differences correlated with the different growth conditions. First, the aerial hyphae which occur only in SSFs are mainly responsible for oxygen uptake. Second, SSF is characterised by gradients in temperature, water activity and nutrient concentration, and inside the hyphae different polyols are accumulating. Third, pelleted growth in SmF and mycelial growth in SSF show different gene expression and protein secretion patterns. With this approach we aim to expand our knowledge of mechanisms of fungal growth on solid substrates and to exploit the biotechnological applications. [source] Utilization of essential oil as natural antifungal against nail-infective fungiFLAVOUR AND FRAGRANCE JOURNAL, Issue 2 2002Mamta Patra Abstract During antifungal screening of some essential oils, Foeniculum vulgare exhibited the strongest activity, completely inhibiting the mycelial growth of the nail-infective fungi, Trichophyton rubrum, T. mentagrophytes and Scytalidium dimidiatum. The essential oil was found to be fungicidal at 0.2, 0.4 and 0.5 µl/ml concentrations. The oil was efficiently active against heavy doses of inoculum at minimum fungicidal concentrations. The fungicidal activity of the oil was found to be thermostable up to 80 °C, with no descramble decrease in activity after 48 months of storage. The oil also showed a broad fungitoxic spectrum, inhibiting the mycelial growth of other nail-infective fungi, viz. Aspergillus flavus, A. fumigatus, A. niger,A. ustus, Candida albicans, Epidermophyton floccosum, Microporum audouinii, M. canis, M. gypseum, M. nanum, Rhizopus nigricans, Trichophyton tonsurans and T. violaceum. Moreover, it did not exhibit any adverse effects on mammalian skin and nails up to 5% concentration. As such, the oil has a potential use as an effective herbal chemotherapeutic after undergoing successful clinical trials. Copyright © 2002 John Wiley & Sons, Ltd. [source] Effect of fungicides, endophytes and fungal filtrates on in vitro growth of Spanish isolates of Gremmeniella abietinaFOREST PATHOLOGY, Issue 4 2007O. Santamaría Summary The effect of eight fungicides and 15 endophytes isolated from twigs of healthy Pinus halepensis trees on the growth rate of four Spanish isolates of the pathogen Gremmeniella abietina was evaluated in vitro. In the fungicide experiments, four doses of each fungicide tested were added to the growth medium. In the endophyte experiments, dual cultures endophyte-pathogen were paired in Petri dishes. Furthermore, growth of three G. abietina isolates was evaluated on malt agar with pine needle extract amended with filtrates from cultures of endophyte E14, which produced a brownish compound apparently inhibiting G. abietina growth. The results obtained suggested that chlorothalonil and daconil were the most suitable fungicides at low doses to reduce growth of G. abietina isolates from Spain. Four of the endophytes tested in vitro showed strong antagonistic activity against G. abietina and deserve further testing in vivo. The endophyte E14 produced in vitro a brownish compound which almost completely inhibited mycelial growth of G. abietina isolates from Spain. [source] Effects of some bacteria (Pseudomonas spp. and Erwinia herbicola) on in vitro growth of Piptoporus betulinusFOREST PATHOLOGY, Issue 6 2000K. Przyby Summary Bacteria including Pseudomonas putida, Pseudomonas fluorescens biovar I, Pseudomonas fluorescens biovar V, Pseudomonas aureofaciens and Erwinia herbicola were isolated from discoloured zones in birch trunks. Antagonistic effects of these bacteria to growth of Piptoporus betulinus mycelium were tested in vitro, both in dual culture and using bacterial cell-free culture filtrates. In dual cultures, P. putida was most effective at inhibiting mycelial growth of Piptoporus betulinus. Filtrates of P. putida inhibited growth of P. betulinus mycelium irrespective of filtrate concentration, incubation time of bacteria and timing of recording mycelium growth. The strongest antagonistic effect (inhibition of fungal growth) was observed on a medium containing 80% of sterile filtrate obtained from 15-day-old bacterial cultures. The highest stimulating effect on mycelium growth was noted on medium containing 80% filtrate obtained from 7-day-old E. herbicola cultures. Résumé Des bactéries, Pseudomonas putida, Pseudomonas fluorescens biovar I, Pseudomonas fluorescens biovar V, Pseudomonas aureofaciens et Erwinia herbicola, ont été isolées de zones colorées de troncs de bouleau. Les effets antagonistes de ces bactéries sur la croissance mycélienne de Piptoporus betulinus ont étéévalués in vitro, en cultures doubles et à partir de filtrats bactériens. En cultures doubles, P. putida a été le plus inhibiteur de la croissance du P. betulinus. Les filtrats de P. putida inhibaient la croissance quel que soit la concentration du filtrat, la durée d'incubation de la bactérie, et le délai dans lequel la croissance mycélienne était mesurée. L'effet inhibiteur le plus fort a été observé sur un milieu contenant 80% de filtrat stérile obtenu de cultures bactériennes de 15 jours. L'effet stimulant le plus fort a été noté sur un milieu contenant 80% d'un filtrat obtenu de cultures de 7 jours de E. herbicola. Zusammenfassung Verschiedene Bakterienarten (Pseudomonas putida, Pseudomonas fluorescens Biovar I, Pseudomonas fluorescens Biovar V, Pseudomonas aureofaciens und E. herbicola) wurden aus verfärbtem Holz in Birkenstämmen isoliert. Antagonistische Effekte dieser Bakterien gegenüber Myzel von Piptoporus betulinus wurden in vitroüberprüft (Dualkulturen und bakterienzellfreie Kulturfiltrate). In Dualkulturen zeigte P. putida den stärksten Hemmeffekt auf das Myzelwachstum von P. betulinus. Filtrate von P. putida hemmten das Wachstum von P. betulinus, unabhängig von der Filtratkonzentration, der Inkubationszeit der Bakterien und dem Zeitpunkt der Messung des Myzelwachstums. Der antagonistische Effekt (Hemmung des Myzelwachstums) war am ausgeprägtesten auf einem Medium, das 80% Sterilfiltrat von 15 Tage alten Bakterienkulturen enthielt. Der stärkste Stimulationseffekt auf das Myzelwachstum wurde auf einem Medium beobachtet, welches 80% Filtrat von sieben Tage alten E. herbicola -Kulturen enthielt. [source] Evaluation of plant oils for suppression of crown rot disease and improvement of shelf life of banana (Musa spp.INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 5 2010AAA subgroup, cv. Robusta) Summary Fourteen plant oils were evaluated to control the crown rot disease caused by Lasiodiplodia theobromae and Colletotrichum musae. Five of these, viz. Ocimum sanctum, Cymbopogan citratus, C. martinii, C. nardus and Pelargonium graveolens oils completely arrested the mycelial growth of both test pathogens at their lowest concentration compared to other oils. Besides, these plant oils have also inhibited the activity of cellulolytic and pectinolytic enzymes produced by these pathogens effectively under in vitro condition. The treatment of banana fruit var. Robusta (Cavendish-AAA) with oils of O. sanctum, C. citratus, C. nardus and C. martinii not only reduced the crown rot severity significantly, but also increased the shelf life of banana fruits. However, under low-temperature storage (14 °C) condition, O. sanctum oil increased the shelf life of banana fruits up to 48 days without affecting their organoleptic properties. Hence, O. sanctum oil could be used as an alternative to chemical fungicides for the management of crown rot disease. [source] Effect of amino acids containing sulfur on dithiolopyrrolone antibiotic productions by Saccharothrix algeriensis NRRL B-24137JOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2006N. Bouras Abstract Aims:, To study the effect of sulfur-containing amino acids (L-cysteine, L-cystine, L-methionine and DL-ethionine) on the production of dithiolopyrrolone antibiotics by Saccharothrix algeriensis NRRL B-24137. Methods and Results:, The production levels of dithiolopyrrolones were investigated by using high performance liquid chromatography in a chemically semi-synthetic medium. The production of the studied antibiotics depends upon the nature, concentration and the time of addition of these sources in the culture medium. Both cysteine and cystine favoured the specific productions of dithiolopyrrolones; iso-butyryl-pyrrothine (ISP) by cysteine, however butanoyl-pyrrothine, senecioyl-pyrrothine and tigloyl-pyrrothine by cystine, when added initially to the culture medium. The maximum specific productions of dithiolopyrrolones were observed in the presence of 5 mmol l,1 cystine for thiolutin, 5 mmol l,1 cysteine for ISP, and 10 mmol l,1 cystine for others studied dithiolopyrrolones as shown in Fig. 3. The production of these antibiotics was decreased when the concentrations of cysteine and cystine were in excess. All dithiolopyrrolone specific productions were strongly inhibited by addition of methionine and ethionine, without inhibition of mycelial growth. Figure 3. Effect of cysteine () and cystine () addition at different concentrations on specific production of thiolutin (a), senecioyl-pyrrothine (b), tigloyl-pyrrothine (c), iso-butyryl-pyrrothine (d) and butanoyl-pyrrothine (e). Specific dithiolopyrrolone productions are given as mg per g of biomass at the time of maximal productions during 96 h of fermentation. Conclusions:, Among all studied amino acids, cystine and cysteine can be used as supplements for improvement the production of dithiolopyrrolone antibiotics by S. algeriensis NRRL B-24137. Significance and Impact of the Study:, Dithiolopyrrolone antibiotics have many important applications for employing them as medicaments, particularly in the treatment of human and animal cancers. In the present work, the influence of containing-sulfur amino acids on dithiolopyrrolone antibiotic productions was studied. The obtained results can be employed for the optimization of the culture medium for the dithiolopyrrolone productions in higher quantities. [source] Growth of Botrytis cinerea and Strawberry Quality in Ozone-enriched AtmospheresJOURNAL OF FOOD SCIENCE, Issue 5 2003A. Nadas ABSTRACT Botrytis cinerea cultures were stored on potato dextrose agar in air with or without 1.5 ,L/L ozone at 2 °C. Cultures stored in the presence of ozone grew slower. Strawberry fruits (Fragaria×ananassa cv. Camarosa) were stored for 3 d at 2 °C in air with or without 1.5 ,L/L ozone and then transferred to room temperature. Each group was inoculated with B. cinerea grown in air with or without ozone. Visible mycelial growth developed more rapidly on fruit previously stored in air. Ozone-enriched cold storage of naturally infected ,Camarosa' fruit reduced decay incidence, weight loss, and fruit softening, but resulted in a reversible loss of fruit aroma. [source] Lipid transfer proteins from Brassica campestris and mung bean surpass mung bean chitinase in exploitabilityJOURNAL OF PEPTIDE SCIENCE, Issue 10 2007Peng Lin Abstract Antifungal peptides with a molecular mass of 9 kDa and an N -terminal sequence demonstrating remarkable similarity to those of nonspecific lipid transfer proteins (nsLTPs) were isolated from seeds of the vegetable Brassica campestris and the mung bean. The purified peptides exerted an inhibitory action on mycelial growth in various fungal species. The antifungal activity of Brassica and mung bean nsLTPs were thermostable, pH-stable, and stable after treatment with pepsin and trypsin. In contrast, the antifungal activity of mung bean chitinase was much less stable to changes in pH and temperature. Brassica LTP inhibited proliferation of hepatoma Hep G2 cells and breast cancer MCF 7 cells with an IC50 of 5.8 and 1.6 µM, respectively, and the activity of HIV-1 reverse transcriptase with an IC50 of 4 µM. However, mung bean LTP and chitinase were devoid of antiproliferative and HIV-1 reverse transcriptase inhibitory activities. In contrast to the mung bean LTP, which exhibited antibacterial activity, Brassica LTP was inactive. All three antifungal peptides lacked mitogenic activity toward splenocytes. These results indicate that the two LTPs have more desirable activities than the chitinase and that there is a dissociation between the antifungal and other activities of these antifungal proteins. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd. [source] Purification of Angularin, A Novel Antifungal Peptide from Adzuki BeansJOURNAL OF PEPTIDE SCIENCE, Issue 3 2002Dr X. Y. Ye Abstract An antifungal peptide was isolated from the adzuki bean with a procedure involving affinity chromatography on Affi-gel blue gel and ion exchange chromatography on CM-Sepharose. The protein designated angularin was adsorbed on both types of chromatographic media and possessed a molecular weight of 8 kDa. Angularin exhibited antifungal activity against a variety of fungal species including Mycospharella arachidiocola and Botrytis cinerea. It inhibited mycelial growth in B. cinerea with an IC50 of 14.3 µM. Fusarium oxysporum and Rhizoctonia solani were not inhibited. Angularin demonstrated inhibitory activity on translation in the rabbit reticulocyte lysate system (IC50 = 8.0 µM) but did not affect proliferation of splenocytes. The activity of HIV-1 reverse transcriptase was inhibited in the presence of angularin. Its N -terminal sequence was GEPGQKE. Copyright © 2002 European Peptide Society and John Wiley & Sons, Ltd. [source] Fungicide Effectiveness during the Various Developmental Stages of Peronophythora litchii In VitroJOURNAL OF PHYTOPATHOLOGY, Issue 7-8 2009Hancheng Wang Abstract Litchi downy blight caused by Peronophythora litchii is one of the most destructive diseases suffered by litchi in China. This study has evaluated the activities of the fungicides dimethomorph (DMM), azoxystrobin (AZB), famoxadone (FMD), metalaxyl (MTL), cymoxanil (CYX) and mancozeb (MCB) on the mycelial growth, sporulation, zoospores release, and germination of sporangia as well as of cystospores of P. litchii. Dimethomorph and MTL inhibited mycelial growth more effectively than the other fungicides tested. Mycelial growth was affected less by MCB, and only weakly by AZB, FMD and CYX. Sporangia production was more strongly reduced by DMM and MTL than by AZB, FMD, CYX or MCB. Zoospore release from the sporangia was most sensitive to AZB and FMD, less sensitive to MCB and insensitive to DMM, MTL and CYX. Direct germination of sporangia of P. litchii was the most strongly inhibited by AZB and FMD, followed by DMM and MCB, whilst the sensitivity of this life stage to MTL and CYX was relatively low. Germination of encysted zoospores of P. litchii was the most sensitive to AZB and FMD, followed by DMM. Mancozeb was moderately active, while MTL and CYX did not inhibit this development stage. This is the first report on the in vitro response of the litchi pathogen, P. litchii, to fungicides. These findings can be valuable tools in setting up efficient disease management programmes to control litchi downy blight. [source] A Suspension Culture Method for the Rapid Mass Culture of Cistella japonica MyceliumJOURNAL OF PHYTOPATHOLOGY, Issue 9 2006T. Yamanobe Abstract Different methods were investigated for the rapid mass culture of Cistella japonica by using water extracts of some nutritional sources. In an agar culture test, there was little difference in mycelial growth in water extracts of wheat bran, rice bran and potato. In suspension culture with wheat bran extract, which is easily and cheaply available, the mycelium of C. japonica increased seven times more than that in agar culture after a month's incubation. C. japonica from suspension culture was pathogenic to Chamaecyparis obtusa. These results suggest that suspension culture in water extract of wheat bran can be adopted for the rapid mass culturing of C. japonica for use in inoculation tests. [source] Induced Resistance in Yali Pear (Pyrus bretschneideri Rehd.) Fruit against Infection by Penicillium expansum by Postharvest Infiltration of Acibenzolar-S-methylJOURNAL OF PHYTOPATHOLOGY, Issue 11-12 2005J. Cao Abstract The objective of the present study was to evaluate how disease resistance in Yali pear fruit (Pyrus bretschneideri Rehd.) was affected by the infiltration of acibenzolar-S-methyl (ASM) after harvest. The disease incidence and lesion area in/on the fruit inoculated with Penicillium expansum significantly (P < 0.05) decreased by the infiltration with 0.5 mm ASM, and the duration of protection conferred by ASM lasted over 15 days. ASM did not directly inhibit the mycelial growth of P. expansum in vitro. However, ASM treatment significantly enhanced activities of the main defence enzymes including peroxidase, phenylalanine ammonia-lyase and chitinase, and activities of antioxidant enzymes including superoxide dismutase and catalase in the fruit during the infection. Two kinds of second metabolites, total phenolic compounds and flavonoids, and two productions of lipid peroxidation, H2O2 and malondialdehyde, were also involved in the resistance and significantly accumulated in ASM-treated fruit in the infection. The inhibitory effect of ASM on the disease may be related to its ability to enhance defence responses in the fruit. The application of ASM in inducing resistance in fruit possesses promising in control of postharvest diseases alternative to fungicides. [source] Identification of Critical Stage for Disease Development and Biocontrol of Alternaria Blight of Indian Mustard (Brassica juncea)JOURNAL OF PHYTOPATHOLOGY, Issue 4 2004P. D. Meena Abstract Fungicides mancozeb and carbendazim caused 100% reduction in mycelial growth of Alternaria brassicae over control in vitro while 1% (w/v) aqueous bulb extract of Allium sativum and leaf extract of Acacia nilotica caused significant reductions. In dual culture, GR isolate of Trichoderma viride performed the best among the test isolates of Trichoderma, causing 81%, 82% reduction in mycelial growth of A. brassicae over control. Performance of isolates SI-2, P and SI-1 of T. viride were at par (P < 0.01) with that of GR isolate. Spraying of A. brassicae at different ages of the mustard host plant identified 75 days after sowing (d.a.s.) as the most critical age of the mustard plant for development of Alternaria blight severity on the crop with 45 d.a.s. being the next most important one. Mancozeb was the best among all the treatments, resulting in the lowest disease severity on leaves of mustard at both Sewar and Ludhavai as also the lowest A-value (area under disease progress curve). Performance of bulb extract of A. sativum in checking the disease severity on leaves and pods was at par (P,<,0.05) with mancozeb. The GR isolate of T. viride was at par with mancozeb in checking blight severity on mustard leaves at Sewar while performance of the bioagent was significantly (P,<,0.05) inferior to the chemical fungicide at Ludhavai. Performance of the bioagent isolate GR of T. viride in checking the disease severity on pods was at par (P < 0.05) with mancozeb at both Sewar and Ludhavai, the treatment recording the lowest A-value on pods. While application of bulb extract of A. sativum resulted in highest seed yield at Sewar in 2001,2002, the bioagent isolate GR of T. viride did so at Ludhavai, both the treatments being at par (P < 0.05) with mancozeb and significantly higher than control. Application of bulb extract of A. sativum at 45 and 75 d.a.s. resulted in lowest blight severity on leaves and pods as also in highest seed yield among the different single and combination of treatments. Although disease severity in the treatment was at par (P < 0.05) with that in mancozeb, application of the plant extract at the two stages of crop growth resulted in significantly higher seed yield compared with the two applications of the chemical fungicide. However, application of the treatments singly only at 75 d.a.s., GR isolate of T. viride at 45 and 75 d.a.s., A. sativum 45 d.a.s. + T. viride 75 d.a.s., and T. viride 45 d.a.s. + A. sativum 75 d.a.s. resulted in seed yield at par (P < 0.05) with application of bulb extract of A. sativum at 45 and 75 d.a.s. [source] Potential of Trichoderma harzianum and T. atroviride to Control Botryosphaeria berengeriana f. sp. piricola, the Cause of Apple Ring RotJOURNAL OF PHYTOPATHOLOGY, Issue 4-5 2002G. KEXIANG Abstract Trichoderma harzianum T88 and T. atroviride T95 were tested for their efficacy in controlling apple ring rot (caused by Botryosphaeria berengeriana f. sp. piricola) in vitro and in the field. Isolates of T88 and T95 produced both volatile and non-volatile antibiotics that suppressed mycelial growth of the pathogen. Light and scanning electron microscopy showed that mycoparasitism by Trichoderma spp. of B. berengeriana f. sp. piricola resulted in penetration and disruption of hyphal cells, and thinning of cytoplasm of the pathogen. The culture filtrates of T88 and T95 in Czapek's liquid medium suppressed conidial germination of the pathogen, and the germination level was negatively correlated with the duration of culture of Trichoderma. In inoculation tests, 32 days after simultaneous inoculation or preinoculation with B. berengeriana f. sp. piricola and Trichoderma spp., the incidence of infected apple shoots was reduced, respectively, by 65.3,76.4% and 62.5,76.4%, and the index of infection reduced by 36.9,38.9 and 40.7,44.4, The effect of inoculating B. berengeriana f. sp. piricola 3 days after the antagonists were inoculated was greater (81.4,88.8%) than simultaneous inoculation (72.2,77.8%). Re-isolation from inoculated apple shoots demonstrated that the pathogen had been suppressed by Trichoderma. The ability to re-isolate the pathogen from apple after co-inoculation and pre-inoculation with Trichoderma spp. was reduced by 27.0,42.3% and 22.2,47.1%, respectively. The biocontrol field trial suggested that the B. berengeriana f. sp. piricola canker on apple shoots and stems and rotting fruit had been efficiently controlled by the application of spore suspensions of T. harzianum T88 and T. atroviride T95. The efficacy of control by Trichoderma is thus similar to that of routine chemical control. [source] Rapid Screening Method of Cassava Cultivars for Resistance to Colletotrichum gloeosporioides f.sp. manihotisJOURNAL OF PHYTOPATHOLOGY, Issue 1 2002C. N. FOKUNANG An in vitro method for assessing cassava anthracnose disease (CAD) resistance was developed as a preliminary screen to a CAD-resistant breeding programme. Potato dextrose agar (PDA) media was amended by extracts from the stem cortex of 10 cassava cultivars (30001; 30572, 30211, 88/02549, 88/00695, 88/01336, 91/00344, 91/00313, 91/00684 and 91/00475), and assayed for efficacy of inhibition of the growth of Colletotrichum gloeosporioides f. sp. manihotis isolates (05FCN, 10FCN, 12FCN, and 18FCN). Morphological and physiological data indicated that there was a significant difference (P , 0.05), in mycelial growth, spore germination and sporulation among the four isolates on PDA amended with cassava stem extracts. Extracts from cassava cultivars 30211, 91/00684 and 91/00313 showed higher inhibition of germ tube development, mycelial growth and sporulation of the fungal isolates, whereas cultivars 88/02549 and 88/01336 showed the least inhibition. The 10 cultivars were further tested in both greenhouse and field conditions, under disease pressure for two planting seasons, to corroborate resistance to the fungus as observed in vitro. Greenhouse and field trials with the 10 cassava cultivars showed a significant difference (P , 0.05) in CAD resistance. Cultivars 88/02549 and 88/01336 were highly CAD-susceptible, as shown in the in vitro assays and confirmed in the greenhouse and field tests. The other eight cultivars were either resistant (30211, 91/00684), or moderately resistant (30572, 88/00695, 91/00475, 91/00344, 30001 and 91/00313) to CAD. The study shows that an in vitro screening assay of cassava for resistance to CAD could serve as a convenient preliminary screening technique to discriminate CAD-resistant from CAD-susceptible cassava cultivars. The in vitro screening method considerably reduces time and labour in comparison with the current screening techniques of cassava, which involve field planting, inoculation and evaluation. [source] Synergistic effect of oligochitosan and silicon on inhibition of Monilinia fructicola infectionsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 4 2010Lingyu Yang Abstract BACKGROUND: Oligochitosan has broad-spectrum antimicrobial activity and shows an obvious inhibitory effect on phytopathogens. In addition, as an exogenous elicitor, it can induce various defence responses, including affecting the activities of several defence-related enzymes and substances in some plants. Owing to this dual function of oligochitosan, it can be used to control postharvest diseases of fruits. Silicon, like oligochitosan, also has a dual function. In this study the synergistic effect of oligochitosan and silicon on the decay control of apple fruit was investigated. RESULTS:In vitro, both oligochitosan and silicon significantly inhibited spore germination, germ tube elongation and mycelial growth of Monilinia fructicola, with higher concentrations having a greater effect. The synergistic effect of oligochitosan and silicon at half-maximal inhibitory concentration on disease control at 25 °C was much better than the effect of oligochitosan or silicon alone, not only in vitro but also in vivo. CONCLUSION: The results showed that a combination of oligochitosan and silicon had a synergistic effect on the control of disease caused by M. fructicola in apple fruit at 25 °C. Copyright © 2010 Society of Chemical Industry [source] Influence of water activity and temperature on conidial germination and mycelial growth of ochratoxigenic isolates of Aspergillus ochraceus on grape juice synthetic medium.JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 10 2005Predictive models Abstract The first stages in the development of Aspergillus ochraceus, an ochratoxin A-producing fungus that infects grapes and may grow on them, have been studied on a synthetic nutrient medium similar to grape in composition. Spore germination and mycelial growth have been tested over a water activity (aw) and temperature range which could approximate to the real conditions of fungal development on grapes. Optimal germination and growth were observed at 30 °C for all three isolates tested. Maximal germination rates were detected at 0.96,0.99 aw at 20 °C, while at 10 and 30 °C the germination rates were significantly higher at 0.99 aw. Although this abiotic factor (aw) had no significant influence on mycelial growth, growth rates obtained at 0.98 aw were slight higher than those at other aw levels. Predictive models for the lag phase before spore germination as a function of water activity and temperature have been obtained by polynomial multiple linear regression, and the resulting response surface models have been plotted. Copyright © 2005 Society of Chemical Industry [source] Inhibitory activity of tea polyphenol and Hanseniaspora uvarum against Botrytis cinerea infectionsLETTERS IN APPLIED MICROBIOLOGY, Issue 3 2010H.M. Liu Abstract Aims:, To investigate the effect of tea polyphenol (TP) and Hanseniaspora uvarum alone or in combination against Botrytis cinerea in grapes and to evaluate the possible mechanisms involved. Methods and Results:, TP alone was effective in controlling grey mould in grape at all concentrations. TP at 0·5 and 1·0% in combination with H. uvarum (1 × 106 CFU ml,1) showed a lower infection rate of grey mould. TP at 0·01% or above significantly inhibited the spore germination of B. cinerea. TP at 0·1% showed inhibition ability on mycelium growth of B. cinerea. The addition of TP did not affect the growth of H. uvarum in vitro and significantly increased the population of H. uvarum in vivo. Conclusions:, TP exhibited an inhibitory effect against B. cinerea and improved the biocontrol efficacy of H. uvarum. The inhibitory effects of spore germination and mycelial growth of B. cinerea and the increased populations of H. uvarum in vivo may be some of the important mechanisms of TP. Significance and Impact of the Study:, The results suggested that TP alone or in combination with biocontrol agents has great potential in the commercial management of postharvest diseases of fruits. [source] Nutritional factors determining sclerotial formation of Polyporus umbellatusLETTERS IN APPLIED MICROBIOLOGY, Issue 2 2009Y.-Y. Liu Abstract Aims:, To find out which nutritional condition is the determining factor for sclerotial formation of Polyporus umbellatus. Methods and Results:, The nutritional requirements of 15 carbohydrates, ten nitrogen compounds, eight vitamins and eight mineral elements were studied for their effects on mycelial growth and sclerotial formation of Polyporus umbellatus using the one-factor-at-a-time method. Only fructose could induce sclerotial formation of P.,umbellatus. An additional test indicated that nitrogen source categories influenced sclerotial formation significantly and that peptone was found to be the best for sclerotial production. Through an orthogonal matrix test, the effects of carbon/nitrogen factors on sclerotial formation were found be in the order: fructose > interaction between fructose and peptone > peptone. The optimal concentration for sclerotial formation was determined to be 50·0 g l,1 fructose and 4·0 g l,1 peptone. Conclusions:, Carbon source is the factor determining sclerotial formation of Polyporus umbellatus. Nitrogen source can influence such a morphological transformation significantly. The categories of vitamin and mineral element do not have relationship with the sclerotial formation. Significance and Impact of the Study:, This study provides the preparatory knowledge for the completely artificial culture of Polyporus umbellatus for its sclerotium. [source] Influence of nutritional conditions on the mycelial growth and exopolysaccharide production in Paecilomyces sinclairiiLETTERS IN APPLIED MICROBIOLOGY, Issue 6 2002S.W. Kim Aims:,The objective of the study was to optimize the submerged culture conditions for the production of exopolysaccharide from Paecilomyces sinclairii. Methods and Results:,The optimal temperature and initial pH for exopolysaccharide production by Paecilomyces sinclairii in shake flask culture were found to be 30°C and 6·0, respectively. Sucrose (60 g l,1) and corn steep powder (10 g l,1) were the most suitable carbon and nitrogen source for exopolysaccharide production. Conclusions:,Under optimal culture medium, the maximum exopolysaccharide concentration in a 5-l stirred-tank fermenter indicated 7·4 g l,1, which was approximately three times higher than that in basal medium. The maximum specific growth rates (,max) and yield coefficient (YP/S) in the optimal culture medium was 0·16 h,1 and 0·19, respectively. Significance and Impact of the Study:,The optimal culture conditions reported in this article can be widely applied to the processes for submerged cultures of other mushrooms. [source] Suppression of anti- Candida activity of macrophages by a quorum-sensing molecule, farnesol, through induction of oxidative stressMICROBIOLOGY AND IMMUNOLOGY, Issue 6 2009Shigeru Abe ABSTRACT Farnesol is well known as a quorum-sensing molecule of Candida albicans. To assess the pathological function of farnesol, its effects on macrophage viability and functions including growth inhibitory activities against C. albicans were examined in vitro. Murine macrophages, when cultured in the presence of 56,112 ,M of farnesol for 1,2 hr, decreased their activity inhibiting the mycelial growth of C. albicans and lost their viability. This suppression of macrophage function by farnesol was neutralized by the coexistence of the anti-oxidants probucol and trolox. Macrophages cultured in the presence of farnesol for 2 hr displayed morphological change of nuclei and DNA fragmentation, which suggested apoptosis of the cells. Intracellular production of ROS in the farnesol-treated macrophages was shown by fluorescence of DCFH-DA and increase of peroxidized materials. These effects of farnesol were blocked by probucol or trolox. These results indicate that farnesol lowered viability of the murine macrophages and suppressed their anti- Candida activity, perhaps through induction of ROS. [source] CPCR1, but not its interacting transcription factor AcFKH1, controls fungal arthrospore formation in Acremonium chrysogenumMOLECULAR MICROBIOLOGY, Issue 5 2005Birgit Hoff Summary Fungal morphogenesis and secondary metabolism are frequently associated; however, the molecular determinants connecting both processes remain largely undefined. Here we demonstrate that CPCR1 (cephalosporin C regulator 1 from Acremonium chrysogenum), a member of the winged helix/regulator factor X (RFX) transcription factor family that regulates cephalosporin C biosynthesis, also controls morphological development in the ,-lactam producer A. chrysogenum. The use of a disruption strain, multicopy strains as well as several recombinant control strains revealed that CPCR1 is required for hyphal fragmentation, and thus the formation of arthrospores. In a ,cpcR1 disruption strain that exhibits only hyphal growth, the wild-type cpcR1 gene was able to restore arthrospore formation; a phenomenon not observed for ,cpcR1 derivatives or non-related genes. The intracellular expression of cpcR1, and control genes (pcbC, egfp) was determined by in vivo monitoring of fluorescent protein fusions. Further, the role of the forkhead transcription factor AcFKH1, which directly interacts with CPCR1, was studied by generating an Acfkh1 knockout strain. In contrast to CPCR1, AcFKH1 is not directly involved in the fragmentation of hyphae. Instead, the presence of AcFKH1 seems to be necessary for CPCR1 function in A. chrysogenum morphogenesis, as overexpression of a functional cpcR1 gene in a ,Acfkh1 background has no effect on arthrospore formation. Moreover, strains lacking Acfkh1 exhibit defects in cell separation, indicating an involvement of the forkhead transcription factor in mycelial growth of A. chrysogenum. Our data offer the potential to control fungal growth in biotechnical processes that require defined morphological stages for optimal production yields. [source] | |||||||||||||||||||||||||||||||