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1
Moore, Jocelyn. "Control of Aspergillus Flavus Infection and Growth." Thesis, University of Louisiana at Lafayette, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10247200.
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Aspergillus flavus infection of agriculturally important crops such as tree nuts, maize, peanuts, and cotton has decreased crop value. Researchers have identified three major approaches to combat A. flavus growth and aflatoxin accumulation: identifying natural resistance in crops, genetically engineering crops for enhanced resistance, and introducing an atoxigenic fungal strain as a competitor. In this dissertation, I investigated two of the three means to control A. flavus growth and infection: genetically engineered crops and identification of natural resistance. My studies of natural resistance in cotton crop show that Sa 1595, a Gossypium hirsutum cultivar, is significantly more susceptible to A. flavus infection; however, no significantly resistant cultivars were observed, but I did observe a trend of diminished susceptibility in A2 186 and Tamcot Sp 23. I then examined synthetic antimicrobial peptide, D4E1, as a means to increase resistance in crops. My research shows that D4E1 effectively increases reactive oxygen species (ROS), an apoptosis precursor at concentrations as low as 1 µM. Breaches in the membrane that allow infiltration and subsequent fluorescence from Sytox® green occur at higher concentrations. Finally, genetically engineered tobacco plants were examined for D4E1 localization. My research shows that the HA-D4E1 construct was present in the most abundance in the chloroplast of plastid transformed plants, while nuclear transformed plants had nuclear localization. All of my findings suggest that cotton crops do not exhibit any significant enhanced natural resistance to A. flavus infection and growth; however, engineering crops with D4E1 will exhibit enhanced crop resistance.
2
Hughes, Glenda May. "Lipid accumulation and utilization during microcycle growth of Aspergillus niger." Thesis, Sheffield Hallam University, 1986. http://shura.shu.ac.uk/19842/.
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Aspergillus niger was grown in fermenter culture under conditions promoting microcycle growth. Following a period of spherical growth at elevated temperatures for 24h, conidiophores developed from the swollen giant cells when the temperature was decreased. Each stage in this microcycle conidiation was photographed and dry weight was determined. Aberrant growth forms sometimes occurred and these are described with the measures taken to attempt to minimize such problems. The lipid content and composition was investigated throughout the microcycle by the use of column and thin layer chromatography and by gas-liquid chromatography. The major classes of neutral lipid were triacyl glycerols, fatty acids, sterols and sterol esters. Changes in composition during the microcycle are discussed in relation to metabolic requirements for the different developmental stages and a function for triacyl glycerol as an energy reserve for conidiation is suggested. The fatty acid composition was also determined throughout the cycle and changes related to growth temperature. The accumulation and utilization of triacyl glycerol was indicative of changes in activity of lipolytic enzymes. However little lipase activity was detected, although enzymes which hydrolysed water-soluble esters were more readily assayed. In order to assess the relative utilization of each of the carbon substrates glucose, L-glutamate and L-alanine, they were provided in a radiolabelled form and the fate of the label followed at intervals throughout the cycle. The majority of the material was used in the production of insoluble cellular material, with smaller amounts incorporated into lipids, water-soluble materials or released as carbon dioxide. Very little label from L-glutamate was detected as lipid. Glutamate was principally used during the later, conidiation, stage of the microcycle. The results are discussed in relation to the different physiological stages of microcycle conidiation and to the observed changes in lipid content and composition.
3
Fortwendel, Jarrod R. "Aspergillus Fumigatus Ras Homologs Regulate Vegetative Growth, Development and Virulence." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1128432277.
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Hassan, Saad A. "Influence of Cholesterol Import on Aspergillus fumigatus Growth and Antifungal Suscepibility." Thesis, University of North Texas, 2003. https://digital.library.unt.edu/ark:/67531/metadc5539/.
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Invasive pulmonary aspergillosis is a life-threatening fungal infection commonly observed in immunocompromised patients and has a mortality rate approaching 100% once the disease is disseminated. Aspergillus fumigatus is the most common pathogen. Early diagnosis improves the prognosis but is very difficult since most signs and symptoms are nonspecific. Antifungal therapy, usually based on sterol biosynthesis inhibitors, is also of limited efficacy. In my attempts to discover a diagnostic sterol marker for aspergillosis, I observed that A. fumigatus incorporates large amounts of cholesterol from serum-containing medium. This observation suggested the hypothesis that exogenous cholesterol from the host can be imported by A. fumigatus and used as a substitute for ergosterol in the cell membrane. This proposed mechanism would reduce the efficacy of antifungal drugs that act as sterol biosynthesis inhibitors. Experiments to test this hypothesis were designed to determine the effects of serum-free and serum-containing medium on growth of A. fumigatus in the presence and absence of azole antifungal agents. The results showed a marked increase in growth in the presence of human serum. Cultures in media containing cholesterol but no serum also showed enhanced growth, a result indicating that a non-cholesterol component of serum is not primarily responsible for the increased growth. However, sterol analysis of A. fumigatus cultured in the absence of inhibitors showed little or no change in ergosterol levels. This result suggested that the imported cholesterol was not being used as membrane sterol. However, in parallel experiments using Itraconazole, an antifungal agent that attenuates sterol biosynthesis by inhibiting the sterol 14a-demethylase (ERG11), ergosterol levels decreased with increasing doses of inhibitor. Moreover, serum-containing medium partially rescued A. fumigatus from the effects of Itraconazole, and a similar rescue effect was observed with serum-free media containing cholesterol. From the preceding results, it can be concluded that human serum enhances A. fumigatus growth, that cholesterol import rescues Aspergillus from the effects of antifungal agents, that the potency of some azole antifungals is decreased by cholesterol, and that imported cholesterol may substitute for membrane ergosterol in the presence of sterol biosynthesis inhibitors.
5
Safaie, Mehran. "Genetic control of hyphal cell growth and polarity in Aspergillus nidulans." Thesis, University of Sheffield, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341792.
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Ellis, William Otoo. "Effect of modified atmosphere packaging on the growth and aflatoxin production by Aspergillus flavus and Aspergillus parasiticus under tropical environmental storage conditions." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41118.
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The combined effect of Modified Atmosphere Packaging (MAP) involving gas packaging, oxygen absorbent and other environmental factors to control aflatoxin production by Aspergillus flavus and Aspergillus parasiticus in both synthetic media and peanuts were studied using a process optimization technique termed Response Surface Methodology (RSM). Regression analysis of the data indicated that water activity (a$ sb{ rm w}$), pH, storage temperature, initial concentration of headspace oxygen and inoculum level were all highly significant factors (p 0%). These changes in the barrier characteristics influenced the headspace gas composition within the product and under modified atmospheres hence the level of aflatoxin detected in these stored products.In conclusion, this study has shown that the combined effect of several "barriers" can be used in conjunction with low oxygen modified atmosphere and high barrier packaging films to inhibit or reduce aflatoxin to safe and acceptable levels, particularly at abusive temperatures encountered during storage.
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Lee, Soo Chan. "The roles of N-myristoylation in cell morphogenesis in Aspergillus nidulans." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-2583.
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Belewa, Xoliswa Vuyokazi. "The effect of tulbaghia violacea plant extract on the growth of aspergillus species." Thesis, Nelson Mandela Metropolitan University, 2009. http://hdl.handle.net/10948/d1008186.
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Traditional medicine has become an important part of healthcare worldwide. It is estimated that about 25 percent of prescribed medicines contain plant products or active compounds derived from plants. In South Africa, traditional medicine forms part of the culture and tradition of most communities. Garlic compounds have been shown to have a variety of antimicrobial properties. Amongst these are antifungal, antibacterial, antiviral and anti protozoal activities. Allicin and its breakdown products have been shown to be the main active compounds which possess these properties. Tulbaghia violacea has been used for the treatment of a variety of illnesses including asthma, fever, oesophageal cancer, constipation and hypertension. This study investigated the antifungal nature of T.violacea on the morphology, spore germination and lipid synthesis of Aspergillus flavus and Aspergillus parasiticus. The results of this study showed that the plant extract inhibited A. flavus growth at a minimal inhibitory concentration of 15mg/ml and was fungicidal at 20mg/ml and above. A. parasiticus was not inhibited at 25mg/ml indicating resistance to the inhibitory component of the plant extract. A measure of metabolic activity using the XTT assay showed reduced metabolic activity in the presence of increasing concentrations of the plant extract. Higher extract concentrations resulted in higher percentage inhibition of fungal growth for both fungal species with up to 98 percent inhibition being observed for the highest extract concentrations for both fungi. Germination was also delayed in the presence of 15mg/ml plant extract concentration by up to 60hr for A. flavus and 48hr for A. parasititcus. The TEM results showed increased thickening of the cell wall with higher extract concentrations. The thickening was greater for A. flavus than for A. parasiticus. Cell wall thickening may be the reason for the delay in germination in both species. Lipid production was reduced in the presence of plant extracts when compared to the control. The plant extracts inhibited triglyceride production at 15mg/ml for both A. flavus and A. parasiticus. The results therefore indicate that T. violacea extracts are antifungal and probably affect germination through interactions with the cell wall. It is possible that the extract affects lipid production in Aspergillus species.
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Moreno, Velásquez Sergio. "The cellular and molecular responses of Aspergillus fumigatus to the antifungal drug caspofungin." Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/the-cellular-and-molecular-responses-of-aspergillus-fumigatus-to-the-antifungal-drug-caspofungin(cf4638e8-6f50-455d-b9b3-2a27fab6da9b).html.
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The opportunistic fungus Aspergillus fumigatus has emerged as one of the most common fungal human pathogens, causing severe and usually fatal systemic infections that account for more than 200,000 cases annually with mortality rates usually exceeding 50%. During infection, the virulence of A. fumigatus highly depends on its capacity to rapidly respond to external stress encounters in the human niche, such as the host immunological response and the activity of antifungal drugs. The echinocandin, caspofungin, is one of most commonly used antifungal drugs to treat intolerant or refractive patients suffering from invasive aspergillosis. Caspofungin disrupts the catalytic subunit of the β-1,3-glucan synthase complex, Fks1, resulting in the reduced production of the main cell wall component of A. fumigatus, the polysaccharide β-1,3-glucan. Despite its clinical relevance in patients with aspergillosis, caspofungin displays attenuated activity at high concentrations, a phenomenon known as âthe paradoxical effectâ. Little is known about the paradoxical growth of A. fumigatus during caspofungin treatment. Therefore, in this thesis, I investigated the key cellular and molecular responses of A. fumigatus upon caspofungin treatment, particularly during paradoxical growth by live-cell imaging. High-resolution confocal live-cell microscopy revealed that treatment with either low (0.5 µg/ml) or high (4 µg/ml) concentrations of caspofungin for 36 h caused similar abnormalities in A. fumigatus, including wider, hyperbranched hyphae, increased septation and repeated hyphal tip lysis. Regenerative intrahyphal growth occurred as a rapid adaptation to the lytic effects of caspofungin on hyphal tips and the dynamic relocation of Fks1 to vacuoles was a key feature observed in response to caspofungin treatment. The reduced amount of β-1,3-glucan resulting from caspofungin treatment was compensated by increased α-1,3-glucan and chitin content in mature hyphal tips. Interestingly, all lysed cells recovered by regenerative intrahyphal growth. However, after 48 h treatment, only cells exposed to high caspofungin concentrations developed paradoxical growth in leading hyphae. This response was associated with a relocalization of Fks1 at hyphal tips. Consistently, cells undergoing paradoxical growth showed normal morphology and ceased to undergo cell lysis, as well as having a normal content of β-1,3-glucan and α-1,3-glucan but not chitin, which remained high. Notably, the localization of the regulatory subunit of the β-1,3-glucan synthase complex, Rho1, was unaffected by caspofungin, but it was required for the development of paradoxical growth. Interestingly, the gene expression of the β-1,3-glucan synthase complex was downregulated by caspofungin treatment. In addition, caspofungin activity induced the nuclear translocation of the Ca+2 regulated transcription factor CrzA to nuclei and only hyphal tip cells in which this translocation occurred underwent cell lysis. Finally, similarly high concentrations of caspofungin also induced paradoxical growth of Aspergillus fumigatus during human A549 alveolar cell invasion. This thesis outlines several critical adaptations that occur at the cellular, subcellular and molecular levels at different times during exposure to high and low concentration of caspofungin.
10
Mitchell, D. "Ecological factors affecting growth and ochratoxim A production of Aspergillus section Nigri species on grapes." Thesis, Cranfield University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.431810.
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Fuller, Kevin. "Comparative analysis of Protein Kinase A homologues in the growth and virulence of Aspergillus fumigatus." University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1288379778.
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Darko, Clara Bernice. "Effects of Storage Conditions of Aspergillus Growth and Aflatoxin Production in Peanuts. A Study in Ghana." Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/75020.
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Peanuts (Arachis-hypogaea) are one of the staples in Ghana, Sub-Saharan Africa, and other developing countries. This leguminous crop is frequently contaminated with aflatoxins, which are secondary metabolites of some Aspergillus fungi, mostly Aspergillus. flavus and Aspergillus parasiticus. Aflatoxins in foods are known to cause liver cancer, stunted growth in children, immune system disorders and economic losses. Aflatoxin contamination of peanuts during storage is worse in the tropics because climatic storage conditions there are almost the same as the optimum conditions for Aspergillus growth: temperature conditions of about 26-43 °C and relative humidity of 62-99%. This study investigated the growth of Aspergillus and the production of aflatoxin in shelled peanuts under varying treatment and packaging conditions. In addition, the appropriate pre-storage treatments and packaging needed to reduce aflatoxin production and to maintain quality of shelled and in-shell peanuts in storage under tropical environments were studied. Another aim was to determine the impact of the switch to hermetic storage on peanut farming and marketing profitability in Ghana.
Different peanut treatments, with and without Aspergillus flavus fungi, were packaged in different systems; specifically, polypropylene woven sacks and hermetic packaging. Peanuts were analyzed for fungi growth, aflatoxin production and lipid oxidation (peroxide value and p-Anisidine value).
Partial roasting and blanching of peanuts eliminated aflatoxigenic fungi and halted aflatoxin production in stored peanuts, increased the effectiveness of peanut sorting and, hence, helped reduce or eliminate aflatoxin levels along the peanut value chain. Additionally, the results of this study demonstrated that hermetic storage, by suppressing aflatoxin production, has the potential for maintaining peanut quality vis a vis polypropylene woven packaging. Profitability analysis conducted as part of this study revealed that the use of the hermetic storage system would not only improve farmer and trader profits, but also reduce the incidence of various ailments attributed to aflatoxins.Ph. D.
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Bhabhra, Ruchi. "The role of the nucleolar protein CgrA in thermotolerant growth, ribosome biogenesis and virulence of Aspergillus fumigatus." Cincinnati, Ohio : University of Cincinnati, 2007. http://rave.ohiolink.edu/etdc//view?acc_num=ucin1185803413.
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Thesis (Ph.D.)--University of Cincinnati, 2007.Advisor: Dr. David S. Askew. Title from electronic thesis title page (viewed Mar. 27, 2009). Keywords: Aspergillus fumigatus; Thermotolerance; Ribosome biogenesis. Includes abstract. Includes bibliographical references.
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Dogan, Tunca. "The Effects Of Hydrogen Peroxide, Gallic Acid And Resveratrol On Growth And Catalase Production Of Aspergillus Fumigatus." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609281/index.pdf.
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The aim of this study was to analyze the effect of hydrogen peroxide and selected phenolic compounds on growth and catalase production of Aspergillus fumigatus. As a result of growing A. fumigatus at different temperatures it was observed that, growth and catalase production of this species were highest at 37 °C. Catalase production was highest in the presence of 1 mM H2O2, yielding a significant 3 fold increase with respect to the control. Biomass was also increased by 1,44 fold with respect to the control sample. H2O2 increased catalase production possibly by inducing oxidative stress as biomass production significantly increased after the depletion of H2O2. Both gallic acid and trans-resveratrol significantly enhanced biomass generation of A. fumigatus (1,17 fold increase at 10 mM gallic acid and 1,45 fold increase at 3 mM resveratrol with respect to controls) and decreased extracellular catalase production (4,33 fold at 25 mM gallic acid and 16,7 fold decrease at 3 mM resveratrol with respect to controls) especially in the first 5 or 6 days of the cultivation where the anti-oxidant activity of the compounds were possibly at their maximum. A sudden and significant rise was observed in extracellular catalase activity between 5th and 7th days of the cultivation in phenolic compound applied samples, possibly owing to the depletion of the antioxidant activity of gallic acid and resveratrol followed by fungal cells&rsquo
response to a sudden increase of oxidative stress by boosting catalase production.
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Iqbal, Qaiser. "Quantification of fungal biomass growth during citric acid production by «Aspergillus niger» on expanded clay solid substrate." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=19292.
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The growth of fungi on sugar rich wastes can be an economical way of producing citric acid. Nevertheless, conditions for the optimum production of citric acid still need to be established. Using Aspergillus niger, the objective of the present study was to measure the effect on citric acid accumulation and fungal biomass, of sugar and nitrogen supplementation namely as glucose and ammonium, respectively. An inert solid substrate (Hydroton® or HSS) made of expanded clay and wetted with a nutrient solution was used to grow A. niger ATCC12846 and measure its fungal biomass with fermentation time. Citric acid accumulation and fungal biomass were measured during 168 h of fermentation with glucose concentrations ranging 0 to 475 g (kg HSS)-1 and ammonium ranging from 2 to 16 g (kg HSS)-1. Fungal biomass growth was monitored by measuring the change of total volatile solids (TVS) less residual glucose and citric acid, and; organic nitrogen accumulation. Glucose and ammonium had a significant effect (P < 0.10) on both fungal biomass and citric acid accumulation. For citric acid, the highest concentration of 52 g and yield of 14% were obtained with 475 and 250 g glucose (kg HSS)-1 and 8 g of N (kg HSS)-1. Nevertheless, only the glucose concentration of 475 g (kg HSS)-1 resulted in citric acid accumulation continuing after reaching a peak in fungal biomass. This high glucose concentration could have yielded more citric acid by using a pH of 5.5 during spore germination and of 2.0 during fungal biomass growth. Because the C:N ratio of the fungal biomass was observed to vary with nitrogen supplementation, it is not recommended to use organic N to quantify fungal biomass.La fermentation de champignons sur des résidus riches en sucre pourrait être une façon économique de produire de l'acide citrique, à condition de bien maîtriser les paramètres de fermentation. La présente étude avait comme objectif d'évaluer l'effet de la charge de sucre, soit en glucose, et d'azote, soit en ammonium, sur la biomasse du champignon Aspergillus niger ATCC12846 et sur sa production d'acide citrique. De l'argile expansée (Hydrotron® ou HSS) fut utilisée comme substrat solide pour le champignon A. niger ATCC 12846. Le substrat fut humecté d'une solution offrant différents taux de glucose, de 0 à 475 g (kg HSS)-1 et d'azote sous forme d'ammonium, de 2 à 16 g (kg HSS)-1. La biomasse fongique fut obtenue en mesurant la masse volatile totale moins la masse résiduelle de glucose et la masse d'acide citrique, et; l'augmentation de la masse d'azote organique. Le taux de glucose et d'ammonium a eu un effet significatif sur la biomasse fongique et la production d'acide citrique pendant les 168 h de fermentation. Une concentration en glucose de 475 et 250 g (kg HSS)-1 maximisaient la concentration de 52 g (kg HSS)-1 et le rendement de 14% en acide citrique, respectivement, avec 8g d'azote (kg HSS)-1. Par contre, seulement la concentration en glucose de 475 g (kg HSS)-1 permettait d'accumuler de l'acide citrique après avoir atteint le plus de biomasse. Un rendement supérieur exigerait un meilleur contrôle du pH à 5.5 pendant le développement des spores et à 2.0 pendant la fermentation. Puisque le ratio C:N de la biomasse fluctuait avec la concentration d'azote dans la solution, il n'est pas recommandé d'utiliser l'azote organique pour suivre l'évolution de la biomasse.
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Miller, Philip F. P. "Involvement of Ca2+ in the regulation of apical growth and branching in the pathogenic fungus Aspergillus fumigatus." Thesis, University of Aberdeen, 1993. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU053094.
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Calcium has been shown to play important roles in the control of tip growth in a wide range of cell types. This thesis sets out to test the effects of exogenous Ca2+ on various morphological events during the life cycle of the human pathogenic fungus Aspergillus fumigatus. The Ca2+ chelating agent EGTA induced marked morphological effects on colonies of A.fumigatus. That is radial growth rate decreased and branching frequency increased with increasing concentration of EGTA. Ion substitution experiments indicated that these effects were due to the chelation of Ca2+ and not Mg2+, Zn 2+, Cu2+ or Fe2+. However, Mn2+ was able to substitute for Ca2+. Calcium ions were required for germ tube emergence but not for the preceding period of spherical growth in spores of A.fumigatus. That is the rate of spherical growth was independent of exogenous [Ca2+ ] but germ tube emergence was retarded and spores became more swollen as exogenous Ca2+ decreased. The effect of applied electrical fields on spores of A.fumigatus was investigated. Germ tubes were anodotropic and polarisation increased with increasing field strength. The galvanotropic response was dependent on Ca2+ and polarisation decreased with exogenous [Ca2+ ]. The effect of exogenous [Ca2+] on growth kinetics of colonies of A.fumigatus growing on solid medium was investigated. When colonies were incubated on medium buffered at pCa 4-8 (10-4-10 -8 M) hyphal growth unit length and mean hyphal extension rate decreased linearly with the log of Ca2+ concentration. In contrast the specific growth rate remained constant over the range pCa 4-7 and was only reduced when colonies were incubated in medium buffered at pCa 8. This suggests that exogenous Ca2+ acts on processes that govern apical growth and branching but do not affect growth per se. The effect of a broad range of Ca2+-channel blockers and calmodulin antagonists on the growth and morphology of colonies of A.fumigatus were also investigated.
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Richie, Daryl Lynn. "The contribution of apoptosis, autophagy, and the unfolded protein response to the growth and virulence of Aspergillus fumigatus." Cincinnati, Ohio : University of Cincinnati, 2009. http://www.ohiolink.edu/etd/view.cgi?acc_num=ucin1231174571.
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Thesis (Ph.D.)--University of Cincinnati, 2009.Advisors: David Askew PhD (Committee Chair), Rhodes Judith PhD (Committee Member), Cushion Melanie PhD (Committee Member), Deepe George MD (Committee Member), Stringer James Ph.D (Committee Member). Title from electronic thesis title page (viewed April 30, 2009). Keywords: Aspergillus; unfolded protein response; autophagy; apoptosis. Includes abstract. Includes bibliographical references.
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Shukla, Nandini Y. "Investigation of Microtubule dynamics and novel Microtubule-associated proteins in growth and development of the filamentous fungus, Aspergillus nidulans." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu149276142029341.
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Akbar, Asya Hussain. "Growth and ochratoxin A production by Aspergillus species in coffee beans : impact of climate change and control using O₃." Thesis, Cranfield University, 2015. http://dspace.lib.cranfield.ac.uk/handle/1826/9264.
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Coffee is an important beverage product in many parts of the world. During the production and processing of coffee the prevailing environmental factors and rate of drying can have a profound influence on colonisation by mycotoxigenic fungi and contamination with ochratoxin A (OTA). In Kuwait, coffee beans are imported from various parts of the world. The objectives of this project were to (a) to examine the diversity of mycotoxigenic fungi found in green and roasted coffee beans bought in the Kuwaiti market from different source countries and identify the dominant fungal populations, (b) to examine the ecology and ochratoxin A production by the ochratoxigenic strains and species isolated, (c) determine the effect of caffeine concentrations in vitro on growth and OTA production by strains from the Aspergillus section Circumdati and Section Niger groups, (d) evaluate the impact of interacting climate change factors (water activity (aw) x temperature x elevated CO2) on growth and OTA production in vitro and in situ, (e) determine the effect of aw and temperature interactions on ecology of strains of two new species, A. aculeatinus and A. sclerotiicarbonarius, isolated from coffee beans and (f) evaluate the efficacy of gaseous ozone (O3) for controlling OTA producing fungi and control of contamination in coffee beans after treatment and after storage. Cont/d.
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FORMENTI, SILVIA. "FUSARIUM VERTICILLIOIDES IN MAIZE: HOW ABIOTIC AND BIOTIC FACTORS CAN INFLUENCE GROWTH AND FUMONISINS PRODUCTION IN FIELD AND DURING STORAGE." Doctoral thesis, Università Cattolica del Sacro Cuore, 2010. http://hdl.handle.net/10280/773.
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In questa tesi di dottorato sono stati indagati i punti critici legati ai fattori biotici e abiotici che possono influenzare la crescita del fungo Fusarium verticillioides, produttore di fumonisine in mais. le fumonisine sono metaboliti secondari prodotte da funghi appartenenti al genere Fusarium e sono state classificate come possibili cancerogene per l’uomo e per gli animali. Gli argomenti trattati nei vari capitoli sono stati: parametri ecologici che condizionano la crescita e l’accumulo di fumonisine nelle prime fasi post raccolta e durante lo stoccaggio; relazione che intercorre tra aw, umidita’ relativa e tipo di ibrido; controllo con mezzi chimici e biologici in campo e in vitro su F. verticillioides e A. flavus.The aim of this work was to collect missing information about critical point related to abiotic and biotic factors that can influence the growth of Fusarium verticillioides in maize and the consequent production of fumonisins in kernels. Fumonisins are secondary metabolites reported as toxigenic in humans and animals. Issues treated are: variables influencing growth and toxin accumulation during post-harvest and storage; the relationship between aw, relative humidity and type of hybrids; chemical and biological control of F. verticillioides e A. flavus in field and in vitro.
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O'Brien, Geraldine. "Aspergillus parasiticus and Coriolus versicolor growth studies in the presence of naphthalene and formaldehyde : fungal growth as a source of, and monitoring system for, sick building syndrome." Thesis, Glasgow Caledonian University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289509.
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Lima, Joel Fernandes. "Caracterização funcional de componentes da resposta ao dano DNA em \'Aspergillus nidulans\': os genes chkA, chkB e ddbA." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/60/60135/tde-06062008-162010/.
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A constante exposição dos diferentes organismos a agentes que danificam a estrutura da molécula do DNA fez com que a célula desenvolvesse mecanismos de reparo que se mostraram conservados durante a evolução. Em células de mamíferos, as vias de reparo ao dano ao DNA e a regulação dos pontos de checagem do ciclo celular atuam de forma coordenada no reparo do dano a fim de evitar uma progressão do ciclo celular antes do reparo e uma possível perpetuação do dano. Além disso, alguns dos componentes dessas vias metabólicas também atuam em outros processos, como replicação, transcrição, recombinação meiótica e silenciamento gênico. NER é um importante mecanismo no processo que reconhece e remove dímeros de ciclobutano e 6-4 pirimidina-pirimidona da estrutura do DNA. Em mamíferos foram identificados sete grupos de complementação para células deficientes de XP (XPA-G). Um desses grupos é XPE, conhecido por possuir forte afinidade ao dano ao DNA causado por luz UV, sendo formado por duas subunidades, DDB1 e DDB2. Uma busca no banco de dados de Aspergillus nidulans utilizando uma seqüência DDB1 de Homo sapiens, revelou uma única seqüência com similaridade relevante denominada como DdbA que não possui nenhuma similaridade com a proteína DDB2. Em Aspergillus nidulans, a proteína DdbA também está envolvida no reparo do dano ao DNA causado por luz UV e 4-NQO, no entanto, vimos aqui, que DdbA está interagindo com as proteínas UvsBATR, H2AX e CshBCSB no reparo ao dano ao DNA causado por MMS, Bleomicina, 4-NQO e luz UV. Além disso, uma análise na expressão do gene ddbA mostrou que ele é induzido por estas drogas, no estresse oxidativo e nos processos de desenvolvimento assexual e sexual de A. nidulans. Nós também vimos que a localização celular de DdbA não foi afetada durante a resposta ao dano ao DNA causado por luz UV e 4-NQO indicando que a proteína DdbA está presente no núcleo independentemente do dano. Em S. pombe, as proteínas serina-treonina quinases CHK1 e CHK2 foram identificadas como essenciais para o bloqueio do ciclo celular na fase S em resposta ao dano ao DNA ou em resposta ao estresse replicacional. Essas quinases são fosforiladas pelas quinases ATM e ATR e tem sido extensivamente caracterizadas em A. nidulans. Neste fungo, as proteínas ChkACHK1 e ChkBCHK2 estão envolvidas na reposta ao dano ao DNA e estão interagindo de forma epistática e sinergística com as proteínas quinases AtmAATM e UvsBATR. Nossos resultados também sugerem que as proteínas ChkA e ChkB podem estar envolvidas em meiose, e atuam em vias complementares durante o bloqueio da fase S do ciclo celular. Além disso, as proteínas AtmA, ChkA, ChkB e UvsB são redundantemente complementares na manutenção do crescimento polar das hifas em Aspergillus nidulans.The constant exposure of different organisms to agents that damage the DNA structure, has provided the cells with repair mechanisms that are conserved during evolution. In mammal cells, the DNA damage repair pathways and the cell cycle checkpoint regulation act together to prevent cell cycle progression before the repair is performed avoiding mutation fixaxion. However these responses are complex and demand overlapping functions and the intersection of many metabolic pathways. NER is an important mechanism in the process that recognize and remove cyclobutane pyrimidine dimers and 6-4 pyrimidine-pyrimidone photoproduct from the DNA structure. In mammals seven complementation groups for XP deficient cells were identified. One of these groups is XPE, known for having strong affinity to the DNA damage caused by UV light and is formed by two subunits DDB1 and DDB2. A search on the Aspergilus nidulans database using a Homo sapiens DDB1 sequence, revealed a single ORF with relevant similarity. The A. nidulans homologue was deleted and named DdbA. ddbA does not have significant similarity to DDB2 protein. In A. nidulans the protein DdbA is involved on the DNA damage repair caused by UV light and 4NQO. Additionaly ddbA is genetically interacting with uvsBATR, histone H2AX and cshBCSB the damage repair caused by MMS , BLEO, 4NQO and UV light. Also, an analysis of the gene ddbA expression indicated that it is induced by MMS, BLEO, 4-NQO, oxidative stressing agents and by the assexual and sexual development processes of A. nidulans. We also verified that the sub-cellular localization of DdbA was not affected by the presence of UV light or 4-NQO indicating that the protein DdbA is constitutively present in the nucleus. In S. pombe, the serine treonine kinases CHK1 and CHK2 proteins were identified as essential to the Sphase blockage in response to the DNA damage or replicational stress. These kinases are phosphorilated by ATR and ATM kinases, respectively and have been extensively characterized in A. nidulans. In this fungus, the proteins ChkACHK1 and ChkBCHK2 are involved on the DNA damage response and are genetically interacting in an epistatic and/or synergistic manner with the AtmAATM and UvsBATR kinases. Our results also sugest that the proteins ChkA and ChkB may also be involved in meiosis and act in a complementary way during the S-phase block. Furthermore the AtmA, ChkA, ChkB e UvsB proteins are complementary redundant for the maintenance of the polar growth in A. nidulans.
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Alamene, Azawei. "Effects of plant essential oils and biocontrol agents on the growth of, and mycotoxin production by, Aspergillus spp. on groundnut." Thesis, University of Nottingham, 2015. http://eprints.nottingham.ac.uk/28731/.
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Groundnut, Arachis hypogaea (L.), can be attacked by a range of pathogens, including Aspergillus species, which can cause accumulation of the mycotoxin aflatoxin. Although some success in controlling this pathogen has been achieved with application of fungicides, their use is not always feasible in developing nations like Nigeria. The aim of this study was, therefore, to evaluate naturally-occurring plant oils and BCAs with a past history of efficacy as alternatives to fungicides for reduction of Aspergillus infection and aflatoxin accumulation in groundnut. Aspergillus strains and thirteen different plant essential oils were tested. The oils were derived from clove, camphor, vanilla, garlic, galangal, green oregano, lemon grass, neem, ginger, basil, tea tree, thyme and onion. The biocontrol agents used were fungi Trichoderma harzianum strain T-22, T. asperellum and T. viride from a commercial biocontrol product, TUSAL, and bacteria Pseudomonas chlororaphis ssp. aureofaciens and Bacillus amyloliquefaciens (strains MBI600, 62P, and 66P). The identities of a strain of A. niger, isolated from Nigerian groundnut samples, and of T. asperellum and T. viride were confirmed by PCR amplification of DNA and sequence comparison to reference isolates in the GenBank database. Some of the plant oils (clove, camphor and vanilla) and biocontrol agents (Trichoderma strains) tested proved effective in inhibiting the A. flavus and A. niger strains used in the research, in both in vitro and in planta experiments. Improved seedling emergence in pathogen-contaminated compost and reduced post-harvest pod infection were observed. Combinations of the most active BCAs and EOs also provided disease suppression. ELISA analysis of aflatoxin B1 in treated, A. flavus-inoculated groundnut pods showed a reduction in toxin concentrations, to a level below that recommended by the European Commission of 15 ppb. Of the control agents tested, the most effective were T. harzianum T-22 as a BCA and probably clove oil as a plant extract. Commercial products based on Trichoderma are used world-wide. EOs, have, to date, had little use in control of Aspergillus infection of groundnut. It was also demonstrated that detection of asymptomatic A. flavus pod infection could be achieved by the traditional method of surface sterilisation and plating out, and by use of a LAMP assay to detect pathogen DNA. The latter could provide a rapid, portable method for A. flavus detection in harvested groundnut pods and could have application in both developed and developing nations. Since low resource growers in nations like Nigeria need alternative, low-cost methods for protecting groundnut from Aspergillus infection, to produce a nutritionally-valuable, high protein foodstuff low in toxin contamination, such alternative methods of disease control may have a future role to play in global food security. It may prove possible to extract antifungal components from appropriate, locally-sourced plant material in a cost-effective manner. However, whether the level of disease control and suppression of aflatoxin accumulation reported here was adequate for possible commercial application is unclear. Further evaluation, including field experiments, is required.
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Syed, Ishtiaq Anmad. "Effect of choline and dimethylaminoethanol on growth and development of wild type, chitin synthase and choline-requiring mutants of Aspergillus Nidulans." Thesis, King's College London (University of London), 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.397980.
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Malavazi, Iran. "Caracterização funcional de diferentes componentes das vias metabólicas de resposta ao dano DNA no fungo filamentoso \'Aspergillus nidulan\'." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/60/60135/tde-01042009-101041/.
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O complexo Mre11 (Mre11/Rad50/Nbs1) é uma componente chave da resposta celular ao dano ao DNA em humanos e recentes observações sugerem que estas proteínas são em parte responsáveis pela interface ente o ensoreamento do dano ao DNA, seu reparo e as funções das proteínas envolvidas nos pontos de checagem do ciclo celular. Em Aspergillus nidulans, a partir de um screening para o isolamento de letais sintéticos na ausência de dineína, o gene sldIRAD50 foi clonado como um desses letais sintéticos através da complementação do fenótipo de deficiência de conidiação do mutante. Foi identificada uma transversão G-C na posição 2509 (Ala-692-Pro) no mutante sldI1444 a qual está presente na região de dobradiça da proteína. Essa mutação causa sensibilidade a vários agentes mutagênicos. Uma linhagem mutante sldIRAD50::pyrG foi construída a qual apresentou também vários defeitos na reposta celular ao dano ao DNA incluindo sensibilidade a várias drogas mutagênicas, defeito no ponto de checagem de replicação do DNA e na viabilidade dos ascosporos. Além disso, o gene sldIRAD50 interage geneticamente com bimEAPC1 para o controle do spindle pole checkpoint durante a segregação cromossômica sugerindo um novo papel para o complexo Mre11. Em atuação paralela com o complexo Mre11, duas proteínas quinases ditas apicais, ATM e ATR coordenam a transdução do sinal do dano ao DNA para proteínas efetoras do reparo. A proteína ATM está mutada na síndrome de instabilidade cromossômica herdada Ataxia Telangiectasia. Para a caracterização do homologo de ATM em A. nidulans AtmA, uma linhagem mutante atmAATM foi isolada. Esse mutante apresentou falha na reposta ao dano ao DNA, como seus homólogos em vários outros organismos mostrando defeitos no ponto de checagem intrafase S e G2/M, além de sensibilidade a camptothecin e bleomicina. Ainda, o extrato protéico bruto desse mutante não foi capaz de fosforilar o homologo de NBS1 em A. nidulans, ScaA. Além das conhecidas funções de ATM na resposta ao dano ao DNA, foi verificado que o mutante atmAATM apresentou uma acelerada cinética de divisão nuclear e severos defeitos no estabelecimento e manutenção do eixo de crescimento polarizado, evidenciando uma função ainda não descrita para ATM no crescimento polar. Provavelmente, AtmA regula a função e/ou localização de proteínas chaves para a formação do eixo de polarização. Diante disso, para investigar as vias metabólicas que são controladas por esse gene, o perfil transcricional do mutante atmAATM, em comparação com a linhagem selvagem foi verificado em diferentes condições de crescimento. Os resultados indicaram um importante papel da via das pentoses fosfato na proliferação celular monitorada pela AtmA. Além disso, foram identificados vários genes com a expressão do mRNA diminuída envolvidos no crescimento polarizado, na síntese de ácido fosfatídico e de ergosterol e no tráfico intracelular, secreção e transporte vesicular. Buscando identificar genes que participam da resposta celular ao dano ao DNA causado pela droga anti topoisomerase I, camptothecin, foram utilizados filtros de macroarray de A. nidulans contendo 2787 genes deste organismo para monitorar a expressão gênica da linhagem selvagem e do mutante uvsBATR, num experimento de indução com CPT por 30, 60 e 120 minutos. Os resultados revelaram um total de 1512 e 1700 genes modulados na linhagem selvagem e uvsBATR respectivamente, em pelo menos um ponto experimental. Seis desses genes que apresentaram aumento da expressão de mRNA na linhagem selvagem e diminuição da linhagem uvsBATR foram caracterizados: fhdA (que codifica para uma proteína com domínio fork-head associated), tprA (uma proteína hipotética que apresenta o domínio tetratrico peptide repeat), mshA (um homólogo MutS6 envolvido em mismatch repair), phbA (um homólogo da prohibitina), uvsCRAD51 e cshA (homólogo da proteína CSB envolvida no reparo por excisão de nucleotídeos e ligada a Síndrome de Cockayne). A indução transcricional desses genes na presença de CPT requer a função de uvsBATR. Estes genes foram deletados e surpreendentemente apenas uvsCRAD51 apresentou sensibilidade a CPT, enquanto os outros mostraram sensibilidade a outros agentes que causam dano ao DNA e estresse oxidativo. Além disso, com exceção de uvsCRAD51, a deleção desses genes leva a supressão parcial da sensibilidade a menadiona e paraquat do mutante uvsBATR. Esses resultados indicaram um comportamento heterogêneo de sensibilidade durante o crescimento na presença de agentes que causam dano direto ou indireto ao DNA, evidenciando que o perfil transcricional não é determinante para predizer a função de um gene na proteção da célula a determinada droga que causa dano ao DNA.The Mre11 protein complex (Mre11/Rad50/Nbs1) has emerged as a central component in the human cellular DNA damage response, and recent observations suggest that these proteins are at least partially responsible for the linking of DNA damage detection to DNA repair and cell cycle checkpoint functions. In Aspergillus nidulans, the sldI1444D mutant was isolated in a screen for dynein synthetic lethals. The sldIRAD50 gene was cloned by complementation of the sporulation deficiency phenotype of this mutant. A transversion G-C at the position 2509 (Ala-692-Proamino acid change) in the sldI1444D mutant causes sensitivity to several DNAdamaging agents. The mutation sldI1 occurs at the CXXC hinge domain of Rad50. An inactivation strain sldIRAD50::pyrG was constructed. Besides sensitivity to a number of DNA-damaging agents, this deletion strain was also impaired in the DNA replication checkpoint response and in ascospore viability. Also, sldIRAD50::pyrG geneticaly interacted with bimEAPC1, acting in the spindle pole checkpoint control during segregation, suggesting a new possible role of Mre11 complex. In parallel to the Mre11 complex, two apical quinases ATM and ATR respond to DNA damage and transduce the signal to effector proteins. In humans, mutations in ATM cause the devastating neurodegenerative disease Ataxia Telangiectasia. Here we characterized the homolog of ATM (AtmA) in the filamentous fungus A. nidulans. The deletion strain atmA presented defects in the DNA damage response as previously shown in other model organisms including intra S-phase and G2/M checkpoint defects, sensitivity to camptothecin and bleomycin. Also, the crude extract from the mutant strain did not phosphorylate the NBS1 homologue ScaA. In addition to its expected role in the DNA damage response, the atmA mutant showed increased nuclear division kinetics and severe defects in polarized hyphal growth, indicating a novel feature for the ATM gene. Probably, AtmA regulates the function and/or localization of landmark proteins required for the formation of a polarity axis. We extended these studies by investigating which pathways are controlled by AtmA during proliferation and polar growth by comparatively determining the transcriptional profile of A. nidulans wild type and atmA mutant strains in different growth conditions. Our results indicated an important role of the pentose phosphate pathway in the fungal proliferation during endogenous DNA damage and polar growth monitored by the AtmA kinase. Furthermore, we identified several genes that have decreased mRNA expression in the atmA mutant that are involved in the formation of polarized hyphae and control of polar growth; in the biosynthesis of phosphatidic acid and ergosterol; and intracellular trafficking, secretion, and vesicular transport. In order to identify genes that responded to the DNA damage mediated by the anti- toposomerase I drug, camptothecin, we used an A. nidulans macroarray carrying sequences of 2,787 genes from this fungus to monitor gene expression of both wild-type and uvsBATR in a time-point experiment where mycelium was exposed to 60, 90 and 120 minutes to the drug. The results revealed a total of 1,512 and 1,700 genes in the wild-type and uvsBATR deletion mutant strain that displayed statistically significant difference in at least one experimental time-point. We characterized six genes that have increased mRNA expression in the presence of CPT in the wild-type strain relative to the uvsBATR mutant strain: fhdA (encoding a fork head associated domain protein), tprA (encoding a hypothetical protein that contains a tetratrico peptide repeat), mshA (encoding a MutS homologue involved in mismatch repair), phbA (encoding a prohibitin homologue), uvsCRAD51 (the homologue of the RAD51 gene), and cshA (encoding a homologue of the excision repair protein ERCC-6 [Cockaynes syndrome protein]). The induced transcript levels of these genes in the presence of CPT required uvsBATR. These genes were deleted, and surprisingly, only the uvsCRAD51 mutant strain was sensitive to CPT; however, the others displayed sensitivity to a range of DNA-damaging and oxidative stress agents. Moreover, with the exception of UvsC, deletion of each of these genes partially suppressed the sensitivity of the uvsB strain to menadione and paraquat. These results indicated a very complex and heterogeneous sensitivity behavior during growth in the presence of agents that directly or indirectly cause DNA damage and the transcriptional response to DNAdamaging agents does not necessarily identify the genes that protect against these agents.
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Powers-Fletcher, Margaret MV. "Secretory Homeostasis and Fungal Pathogenesis: Characterization of the Contribution of Calnexin, SrgA, and the IreA Kinase to the Growth and Virulence of Aspergillus fumigatus." University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1378393997.
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Nazir, Tahir Muhammad. "Growth of filamentous fungi in pure olive oil : a fundamental study for application to vegetable oil-derived waste streams." Thesis, Högskolan i Borås, Akademin för textil, teknik och ekonomi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-23624.
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Vegetable oil is more difficult to degrade by microorganisms in comparison to carbohydrates and protein. Thus, it creates serious environmental and health concerns if oil-derived waste streams produced by restaurants and industries remain untreated. In this study, a strategy has been developed to grow filamentous fungi in pure olive oil so that it can be used as a bench-mark for growth in olive oil mill sidestreams. The growth of different strains (Aspergillus oryzae, Neurospora intermedia and Rhizopus oryzae) was tested in pure olive oil. A pre-germination stage using glucose as carbon and energy source, or the addition of yeast extract, were found necessary for successful fungal growth in olive oil. Here, A. oryzae showed a superior performance in comparison to N. intermedia and R. oryzae. Medium pH did not impact A. oryzae growth in olive oil, whereas a concentration higher than 40 g/L of the latter impaired the growth of the ascomycete. Obtained biomasses from A. oryzae and N. intermedia cultivations in olive oil were analyzed and compared for protein, fat, ash, and alkali-insoluble material (cell wall content), where the presence of olive oil had a steering effect. The fungal biomass of A. oryzae, obtained from cultivation in the absence of olive oil, contained 0.33% fat and 48% protein, whereas the respective values in the presence of olive oil were 31% and 14%. Similar trends on fat and protein contents were observed for the biomass of N. intermedia. Sudan black staining was also performed on fresh biomass which clearly indicated the presence of oil globules inside the fungal cells. This research can be a fundamental step towards treatment of oil-based waste streams, which entails high-energy and costs if treated, or environmental impacts during informal discharges. Moreover, the fact that the composition of fungal biomass can be steered through addition of olive oil increases the versatility of the originated biomass for various applications, namely in feed, food and biofuel production.
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Ben, M'henni Yosra. "Gestion de la maladie de dépérissement du pommier : criblage in vitro et in planta des activités protectrices d’une collection de microorganismes contre les Pythiacées et caractérisation chimique du principal actif produit par l’isolat A. westerdijkiae A7 Biocontrol and growth promotion potential of combined application of Trichoderma simmonsii and Aspergillus westerdijkiae in Apple root stock dieback." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASS127.
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Le dépérissement du pommier est une maladie tellurique causée par plusieurs espèces Pythiacée. Il est responsable de graves dommages et de pertes d'arbres dans de nombreux vergers en Tunisie. Comme la lutte chimique contre cette maladie pose des problèmes éco toxicologiques et les moyens prophylactiques ont des efficacités limitées, d’autres moyens de lutte sont activement recherchés. L’objectif de cette thèse était d’identifier un nouvel agent de lutte biologique contre les oomycètes responsables de cette maladie à partir d’une collection d’isolats fongiques et bactériens Tunisiens comme alternative au contrôle chimique. Les isolats fongiques étudiés appartenaient aux genres Trichoderma, Aspergillus et Penicillium spp., les isolats bactériens appartenaient au genre Bacillus spp. clade subtilis. Les isolats fongiques ont fortement inhibé la croissance in vitro des Pythiacées (> 40%) par rapport aux isolats bactériens ; en particulier, les filtrats de culture des isolats A. westerdijkiae A7 et T. simmonsii A2. L'évaluation de l’activité préventive et curative contre les Pythiacées sur des porte-greffes du pommier de ces deux isolats fongiques et de la souche Bacillus B2 a montré que T. simmonsii A2 était le plus efficace lorsqu'il était appliqué à titre préventif. De même, la combinaison de la souche Bacillus B2 et de l’isolat A. westerdijkiae A7 a induit une bonne protection contre les Pythiacées en préventif. La combinaison des isolats T. simmonsii A2 et A. westerdijkiae A7 a entraîné une meilleure protection en traitement curatif, alors que la combinaison des trois isolats ensemble réduisait fortement l’activité protectrice. Notre étude révèle le potentiel des isolats Tunisiens, seuls ou en combinaison, en tant qu'agents de lutte biologique contre le dépérissement du pommier ainsi qu'un effet bénéfique supplémentaire sur la croissance végétale observé au niveau des racines et de la longueur des tiges. Ainsi, nous avons sélectionnés les meilleurs candidats agissant par antibiose pour l'identification des principaux agents actifs responsables de l'activité anti-oomycète. L'isolat A. westerdijkiae A7 a été retenu avec 100% d'inhibition de la croissance mycélienne des isolats de Pythiacées testés. Plusieurs étapes de purification successives du filtrat de culture ont permis d’identifier l'acide pénicillique (acide 3-méhoxy-5-méthyl-4-oxo-2,5-hexadiénoïque) en tant que principale molécule responsable de l’inhibition la croissance mycélienne des Pythiacées testées. Étant donné que l’acide pénicillique possède des propriétés toxiques pour la santé humaine et animale, l’isolat A. westerdijkiae A7 ne pourra pas être utilisé en tant que BCA puisqu’il produit cette mycotoxine malgré nos résultats prometteurs in planta. L’ensemble de ces travaux montre le potentiel anti-oomycète des micro-organismes in vitro qui peut différer de l’activité protectrice contre les Pythiacées in planta. Ils révèlent également la nécessité de caractériser l’ingrédient actif pour les études de toxicité nécessaire au développement d’un produit de bio-contrôleApple dieback is a telluric disease caused by several Pythiaceae species. It is responsible for serious damage and loss of trees in many orchards in Tunisia. As the chemical control of this disease poses eco-toxicological problems and the prophylactic means have limited effectiveness, other means of fight are actively sought. The objective of this thesis was to identify a new biological control agent against oomycetes responsible for this disease from a collection of Tunisian fungal and bacterial isolates as an alternative to chemical control. The fungal isolates studied belonged to the genera Trichoderma, Aspergillus and Penicillium spp., The bacterial isolates to the genus Bacillus spp. clade subtilis. Fungal isolates strongly inhibited the growth of Pythiaceae in vitro (> 40%) compared to bacterial isolates; in particular, the culture filtrates of isolates A. westerdijkiae A7 and T. simmonsii A2. The evaluation of the preventive and curative activity against Pythiaceae on apple rootstocks of these two fungal isolates and of the Bacillus B2 strain showed that T. simmonsii A2 was the most effective when applied preventively. Likewise, the combination of the Bacillus B2 strain and the A. westerdijkiae A7 isolate induced good protection against Pythiaceae as a preventive measure. The combination of the T. simmonsii A2 and A. westerdijkiae A7 isolates resulted in better protection in curative therapy, while the combination of the three isolates together greatly reduced the protective activity. Our study reveals the potential of Tunisian isolates, alone or in combination, as biological control agents against apple dieback as well as an additional beneficial effect on plant growth observed at the level of the roots and the length of the stems. Thus, we have selected the best candidates acting by antibiosis for the identification of the main active agents responsible for anti-oomycete activity. The A. westerdijkiae A7 isolate was retained with 100% inhibition of mycelial growth of the Pythiaceae isolates tested. Several successive purification steps of the culture filtrate made it possible to identify penicillic acid (3-mehoxy-5-methyl-4-oxo-2,5-hexadienoic acid) as the main molecule responsible for inhibiting growth mycelia of the Pythiaceae tested. Since penicillic acid has toxic properties for human and animal health, isolate A. westerdijkiae A7 cannot be used as BCA since it produces this mycotoxin despite our promising results in planta. All of this work shows the anti-oomycete potential of microorganisms in vitro, which may differ from the protective activity against Pythiaceae in planta. They also reveal the need to characterize the active molecule for the toxicity studies necessary for the development of a biocontrol product
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Lin, Xiaorong. "Polar tip growth of Aspergillus nidulans." 2003. http://purl.galileo.usg.edu/uga%5Fetd/lin%5Fxiaorong%5F200305%5Fphd.
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Nwoko, Uzom U. "Aspergillus ochraceus growth kinetics in relation to ochratoxin A biosynthesis." 1993. http://hdl.handle.net/1993/17783.
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Chen, Shu-Cheng, and 陳菽承. "Effects of different Aspergillus fermentation products on growth performance in broilers." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/mk32ur.
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碩士國立嘉義大學
動物科學系研究所
107
The study wad divided into four parts. The First part is to investigate the effects of different concentrations of fermentation products from Aspergillus flavus (AF) or Aspergillus niger (AN) on growth performance in broilers. 360 Ross 308 female broilers were randomly distributed into groups in which diet supplemented with 0, 0.05, 0.10, 0.15 and 0.20% AF or AN fermentation products, respectively. There were 4 replicates in each treatment and chickens were ad libitum access to food and water and the experiment last for 35 days. Result showed that the AF and AN fermentation products could improve growth performance of broilers. And 0.20% AN and 0.15% AF groups had better improvements than others. The Second part is the effect of different fermemtation substrates with moisture content on the solid-fermemtation condition for AN, AF, and AO. Resuls showed that the growth rate of mycelium and spore color of AN reached an ideal condition when soybean hull was selected as a solid fermentation substrate with 60% moisture. The ability of AO to decompose different subtrates was less AN and AF. All strains in this test showed certain decomposition ability. The third part is to investigate the effects of different Aspergillus fermentation products on growth performance of broilers. 200 0-day-old female broilers (ROSS 308) were randomly distributed into diets with 0.1% AN fermentation products used wheat bran as solid-fermentation substrates as positive control, 0% (control group) or 0.1% AO and AN fermentation products used soybean hull as solid-fermentation substrates were added to the corn-soybean meal base diet. There were 4 replicates in each treatment and the experiment last for 21 days. Results showed that despite of positive effect on body weight and weight gain in the early stage in 0.1% AO group, AN and AF showed the better performance in FCR. Furthermore, 0.1% AO has the best PEF. These results showed that 0.1% AO fermentation product used soybean hull as solid-fermentation substrates has the best performance in the early stage in broiler. The purpose of fourth part is to investigate the effect of adding different amounts of Aspergillus fermentation products on the growth, carcass, physiology of digestive tract and clinical blood biochemistry in broilers. The results showed that the addition of 0.05% AO + 0.05% AN fermentation product in broiler diet could improve growth performance and carcass traits (P <0.05). In respect to the blood biochemistry, despite the level of Ca in serum in 0.10% AN group was significantly different (P < 0.05) than other group, other results in 0.05% AO, 0.02% AO, 0.05% AN + 0.05% AO fermentation product group were similar to control group . In conclusion, Aspergillus fermentation products have positive effect on growth performance, and supplementing 0.05% AN and 0.05% AO in diet have the best potential to develop as a economic feed additive in broiler. Key words: Aspergillus spp., solid-state fermentation, soybean hulls, broiler
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(9865223), Chih-Hsuan Chang. "Influence of temperature, water activity, and oil content on growth and aflatoxin production on oil seeds by Aspergillus flavus and A. parasiticus." Thesis, 2020.
Find full textAbstract:
Aflatoxins (AFs) are highly toxic second metabolites produced by Aspergillus flavus and A. parasiticus. They are widely detected in cereals, spices, and drinks worldwide. Aflatoxin contamination of foods and crops poses a high health risk for humans and livestock. It is well known that environmental conditions and substrates could influence fungal growth and aflatoxin production. This study tested the effect of water activity (0.82, 0.86, 0.90, 0.94, and 0.98 aw) and incubation temperatures (20°, 27°, and 35°C) on the growth and aflatoxin production of A. flavus and A. parasiticus on ground flax seeds and ground niger seeds. The effect of oil contents of ground niger seeds on fungal growth and aflatoxin production was also investigated in this study.
These two fungal species could not grow on any of the tested substrates with 0.82 aw at 20°, 27°, or 35°C. Aspergillus flavus grew most rapidly on flax seeds with 0.90 aw at 27°C and also 0.94 aw at 27° or 35°C. However, on niger seeds, A. flavus grew best at 0.90 or 0.94 aw incubated at 35°C as well as at 0.94 or 0.98 aw incubated at 27°C. Aspergillus parasiticus showed the optimum growth on flax seeds with 0.90 aw at 35°C, whereas on niger seeds, the optimum occurred on seeds with 0.90 aw at 35°C and also on seeds with 0.94 aw at 27° or 35°C. The optimum conditions for A. flavus to produce high levels of aflatoxins (270-299 μg/kg) on flax seeds were 0.90 aw at 35°C; whereas, the optimum conditions for A. flavus to produce aflatoxin (203-278 μg/kg) on niger seeds were 0.90 or 0.98 aw at 27°C and also 0.90 aw at 35°C. Aspergillus parasiticus produced high levels of aflatoxins (284-365 μg/kg) on flax seeds under the following three conditions, 0.86 or 0.98 aw at 35°C and 0.94 aw at 27°C; A. parasiticus produced 200-384 μg/kg of aflatoxins on niger seeds under nine out of 12 tested incubation conditions.
Reducing mean oil contents from 35.2 to 10.5% of ground niger seeds had very little effect on the growth of the two fungi but significantly decreased their aflatoxin production under certain incubation conditions. On de-oiled niger seeds inoculated with A. flavus, only 13μg/kg of AFB1 was found on seeds with 0.94 aw at 27°C; whereas, on de-oiled niger seeds inoculated with A. parasiticus, high levels of aflatoxins (245-345 μg/kg) were only detected under the three following incubation conditions, 0.90 or 0.94 aw at 27°C, and 0.86 aw at 35°C.
This study showed that the optimum growth and aflatoxin production by A. flavus and A. parasiticus were not identical and influenced by incubation conditions, including temperature, water activity, and growth substrates. The results of this study could help establish guidelines for post-harvest and storage conditions for oil seeds to prevent fungal growth and aflatoxin formation.
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Kulkarni, Kaumudi. "Aspergillus nidulans septin AspD appears to regulate new growth emergence in the vegetative phase." 2008. http://purl.galileo.usg.edu/uga%5Fetd/kulkarni%5Fkaumudi%5Fa%5F200805%5Fms.
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"Galactofuranose biosynthesis is important for maintaining normal growth and cell wall properties in Aspergillus nidulans." Thesis, 2014. http://hdl.handle.net/10388/ETD-2014-02-1434.
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The cell wall is essential for fungal survival in natural environments. Galactofuranose (Galf) decorates certain carbohydrates and lipids of Aspergillus cell wall, is absent in humans and appears to play a role in fungal cell wall maturation. Previous studies in our lab showed that deletion of any of three sequential-acting genes (ugeA, ugmA, and ugtA) of Galf pathway caused substantially reduced growth and spore production.
Two genes upstream of the Galf pathway, galD and galE are essential for galactose metabolism in many systems including the budding yeast, Saccharomyces cerevisiae. Interestingly, characterization of galD and galE in A. nidulans using cell and molecular techniques showed that unlike yeast, neither of these genes was essential for growth at physiological pH 7.5. Nevertheless for each case, their expressions were up-regulated by
growth on galactose, revealing the relative complexity of galactose metabolism in A. nidulans.
Our study also showed that repression of the three sequentially acting Galf pathway genes by conditional promoters phenocopied previously characterized deletion morphology. Using anti-Galf (L10) we also showed that deletion and repression of these genes caused no Galf in the hyphal wall. Gene deletion or repression also increased sensitivity to the wall-targeting drug, caspofungin. Related results from qPCR showed that deletion or repression of ugmA increased gene expression of α-glucan synthase agsB and decreased that of β-glucan synthase fksA. Therefore, Galf is non-essential but important for many aspects of Aspergillus growth,
sporulation, and wall maturation. Aspergillosis, the most common airborne systemic fungal disease, is typically caused by Aspergillus fumigatus. Several A. fumigatus UgmA (AfUgmA) mutants with altered enzyme activity due to single amino acid changes were used to assess their effect on growth
and wall composition in A. nidulans. Wild type AfugmA complemented the phenotypic defects in an A. nidulans ugmAΔ strain, consistent with these two genes being homologous.
The AfUgmA crystal structure has been solved, and the in vitro enzymatic effects of specific mutations in the enzyme active site have been published. AfUgmA mutated strains with reduced activity in vitro impaired A. nidulans growth in a manner substantially similar to gene deletion and gene down-regulation. Site directed mutagenesis showed that AfUgmA residues R182 and R327 were critical for Galf generation both in vivo and in vitro. This supports previous results showing that UgmA is essential for Galf biosynthesis. Using fluorescent latex beads, we showed that reduction of wall Galf increased hyphal surface adhesion. Consistent with qPCR studies, immunofluorescence and ELISA results showed that loss or absence of Galf increased wall α-glucan but reduced wall β -glucan. Galf is important for wall surface integrity and for maintaining dynamic co-ordination with other pathways. To begin to assess this dynamic co-ordination, Tandem Affinity Purification (TAP) tagging combined with
LC-MS/MS was used to identify the interacting partners of UgmA. Our results showed that UgmA interacted with proteins that are involved in cytoskeleton generation, osmotic adaptation, and cell signalling pathway. Further study will help us to understand the dynamic coordination of Galf biosynthesis pathway with other wall carbohydrate polymers for Aspergillus wall formation.
In summary, my thesis results have clearly shown that Galf plays important roles in Aspergillus growth, and wall surface integrity. We also showed that Galf deficient strains are hypersensitive to wall-targeting drugs, indicating that Galf biosynthesis pathway could be potential target for combination therapy. The Galf pathway also maintained a dynamic co-ordination with alpha-glucan and beta-glucan carbohydrate pathways. Future study may include developing an inhibitor against UgmA and exploring the relationship of Galf pathway with alpha-glucan and beta-glucan carbohydrate pathways.
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Wang, Shiao-Chi, and 汪曉琪. "The Inhibitory Effects of Seven Allium Species Against the Growth of Aspergillus Flavus and A.fumigatus." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/11826252759203633841.
Full textAbstract:
碩士中山醫學院
營養科學研究所
86
Aspergillosis is a nosocomial fungal infection. This infection threatens patients and healthy workers in many hospitals. Both Aspergillus flavus and A. fumigatus are the fungi responsible for this fetal disease. The medicine used for this infection has many side-effects, which deteriorates the health of infected persons. Therefore, the search for new antifungal agents is undergoing. The antifungal activity of garlic, one member of Allium family, has been studied. However,little attention was paid to other Allium members. This study was designed to examine the antifungal activity of seven Allium species against the growth of Aspergillus flavus and A. fumigatus. The influence of NACI, HCI acetic acid and heating time upon the antifungal activity of these food samples was studied. Finally, the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of these foods against these two fungi were measured. The results showed that garlic, green garlic, green onion,onion, leek, leek flower and shallot possessed antifungal activity.After 0.2M or 0.4M NaCl treated, only leek and leek flower decreased their antifungal activity (p<0.05). All HCI treatments and acetic acid treatments at pH=4, 6 did not affect the antifungal activity of these Allium plants (p<0.05). However, acetic acid treatments at pH=2 significantly enhanced the antifungal activity of all food samples (p<0.05). When heating at 100°C the antifungal activity of all food samples (p<0.05).When heating at 100°C, the antifungal activity of food samples decreased with increasing heating time (p<0.05). Garlic showed the lowest MIC and MFC, and followed by green garlic ,leek and leek flower (p<0.05).The MIC and MFC of onion was the highest (p<0.05). These results suggested that the seven Allium members, in fresh, have potential in clinical application for aspergillosis prevention or therapy .The presence of NaCl or acetic acid in food preparation would not decrease the antifungal activity these Allium plants.
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(8116817), Yung-Chen Hsu. "INFLUENCE OF WATER ACTIVITY, TEMPERATURE, OIL CONTENT AND PROBIOTIC BACTERIA ON GROWTH AND OCHRATXOIN A PRODUCTION BY ASPERGILLUS FRESENII AND ASPERGILLUS SULPHUREUS." Thesis, 2019.
Find full textAbstract:
Ochratoxin A (OTA) is a ubiquitous mycotoxin produced by some species of Aspergillus and Penicillium. It has been detected in a variety of foods such as cereals, coffee, grapes, cocoa, wine, and spices. Consumption of OTA has been linked to kidney and liver diseases. The aims of this study were to determine the effects of (1) water activity and temperature (2) oil content and grinding and (3) probiotic bacteria on fungal growth and OTA production by Aspergillus fresenii and A. sulphureus. In the first study, the two fungi were grown on ground Niger seeds with 0.82, 0.86, 0.90, 0.94 or 0.98 aw and incubated at 20, 30 or 37°C individually. The two species showed similar growth patterns on Niger seeds under all of the testing conditions. There was no fungal growth on ground Niger seeds with 0.82 aw and the optimal growth condition for the two species on ground Niger seeds was 0.94 aw at 30°C. However, the optimal conditions for OTA production by A. fresenii and A. sulphureus were different. The optimal conditions for A. fresenii to produce OTA on ground Niger seeds was 0.90-0.94 aw at 37°C; whereas, A. sulphureus produced OTA optimally with 0.90-0.94 aw at 30°C as well as 0.94-0.98 aw at 20°C. Overall, A. sulphureus produced higher levels of OTA than did A. fresenii. The highest concentration of OTA (643 μg/kg) produced by A. fresenii was detected on seed samples with 0.90 aw incubated at 37°C for 15 days, while the highest concentration of OTA (724 μg/kg) produced by A. sulphureus was detected on samples with 0.98 aw incubated at 20°C for 10 days.
In the second study, growth and OTA production by the two fungi on ground Niger seeds with different oil content (10, 25 and 35%) and on whole Niger seeds at 30°C were compared. All seed samples were adjusted to 0.94 aw in this study. The two fungi grew most rapidly on ground seeds with 35% oil content, producing high concentrations of OTA (229-453 μg/kg). On whole seeds, A. sulphureus and A. fresenii displayed slow growth until day 5 or 10, respectively, growing rapidly after that. The two species produced either non-detectable or below the limit of quantitation (<4 μg/kg) of OTA in ground seeds with 10 or 25% oil or in whole seeds during the 30-day incubation at 30°C.
In the third study, growth inhibition of A. fresenii and A. sulphureus by probiotic bacteria Bacillus coagulans, B. coagulans (strains unique IS2TM and GBI-306086), Lactobacillus acidophilus (strains LA-5 and LA-14), L. plantarum (strains 299V and LP115), and L. rhamnosus
was evaluated. Results of co-cultured method revealed that L. plantarum 299V had the highest levels of inhibition against the two fungal species; whereas, L. plantarum LP115, and L. rhamnosus showed only some inhibition effect against A. sulphureus and very little inhibition against A. fresenii. The two fungal species were not inhibited by L. acidophilus or B. coagulans.
Results from double-layer testing showed that the two L. plantarum strains and L. rhamnosus inhibited fungal growth completely when there were as few as 40-70 CFU probiotic bacterial colonies in the bottom layer of MRS agar; whereas, L. acidophilus inhibited fungal growth completely when the probiotic colonies were >125 CFU/plate. The three B. coagulans strains showed only partial growth inhibition against A. fresenii with 103 CFU/plate. Bacillus coagulans (unique IS2TM and GBI-306086) completely inhibited growth of A. sulphureus when there were as few as 40-70 CFU/plate; while B. coagulans completely inhibited the growth of A. sulphureus but only when there were >103 CFU plate. Even though the two fungal species were inhibited by some probiotic bacteria on MRS plates, the OTA production was not influenced.
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Spangler, Lindsay M. Luthe Dawn S. "Impact of lignin and caffeoyl coenzyme a o-methyltransferase 1 on Aspergillus flavus growth in maize cobs." 2008. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-2911/index.html.
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Ottenheim, Christoph, Katharina A. Werner, Wolfgang Zimmermann, and Jin Chua Wu. "Improved endoxylanase production and colony morphology of Aspergillus niger DSM 26641 by g-ray induced mutagenesis." 2015. https://ul.qucosa.de/id/qucosa%3A16854.
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Aspergillus niger DSM 26641 was exposed to 60Co g-radiation to enhance the b-1,4-endoxylanase activity, restrict colony growth and improve robustness of pellets. The first promising mutant obtained after g-radiation of the fungal spores at 50-2000 Gy showed a restricted colony growth and an 82% enhancement in b-1,4-endoxylanase activity. The mutant was subjected to a second round of g-radiation at 1400 Gy generating a mutant with double the b-1,4-endoxylanase activity compared to the native strain. The selected final mutant, deposited as Aspergillus niger DSM 28712, showed a maximal saccharification activity of 26 U·ml-1 on xylan based broth, 48 U·ml-1 on lignocellulose hydrolysate and 375 U·ml-1 on lignocellulose hydrolysate supplemented with yeast extract and mineral salts.
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Li, Juh-Yiing, and 李鑄穎. "Effect of Mushroom Biologically Active Substance 10-Oxo-trans-8- decenoic Acid on the Growth of Agrocybe aegerita and Aspergillus spp." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/54521657878490163284.
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碩士國立中興大學
食品科學系
85
10-Oxo-trans-8-decenoic acid (10-ODA) is a product formed concurrently with 1-octen-3-ol, the major mushroom aroma component, from linoleic acid by the action of lipoxygenase and hydroperoxide lyase when the mushroom tissue is damaged or disrupted. 1-Octen-3-ol is the principle characteristic of mushroom flavor, while 10-ODA that is a biologically active substance or growth hormone of mushroom, promotes mycelial growth and stipe elongation. Agrocybe cylindracea is a newly cultivated edible mushroom. It has good taste and high nutritional value. Aspergillus spp. is an important species for fermentary industry. It is widely used in the soy sauce brewing. Many attempts have been reported to increase yields of enzymes or fermentation products of such filamentous fungi. Therefore, in this study, the effect of 10-ODA on the growth of Agrocybe cylindracea (strain B, strain M, strainW) in liquid culture and on PDY agar was studied. The important Aspergillus oryzae and Aspergillus niger in food fermentation was studied and the effect of activities of major enzyme was also evaluated. On the linear growth rate, 10-ODA had a significant effect on the mycelial growth of Agrocybe cylindracea and Aspergillus spp. The relative linear growth rate of strain B, strain M and strainW were 1.131, 1.216 and 1.113 at the concentration of 10 ppm 10-ODA, respectively. For Aspergillus spp., the relative linear growth rate of A. oryzae and A. niger were 1.177 and 1.172, respectively. In liquid culture of Agrocybe cylindracea, for 10 days, the dry matter of mycelium of strains B, M and W at 10 ppm 10-ODA were about 112%, 116% and 114% of mycelium growth compared to the control, respectively. The laccase activity of mycelium of strains B, M and W were increased to 260% (10 ppm), 180% (10 ppm), and 300% (5 ppm) of mycelium growth compared to the control. The enzyme activities of Aspergillus spp. in PDY agar were stimulated by 10-ODA at high concentrations. The effect of 10-ODA on the activity of protease of A. oryzae and A. niger were increased from 118.61 and 92.07 U/g dry wt. compared to control to 146.09 and 112.22 U/g at 10 ppm 10-ODA, respectively. For 5 days, the cellulase activities of A. oryzae and A. niger were increased from 1.66 and 1.75 U/g dry wt. to 1.9 and 2.11 U/g. Those of α -amylase were increased from 2.04 and 2.85 U/g dry wt. to 2.65 and 3.92 U/g. β -Amylase were increased from 5.21 and 6.34 U/g dry wt. to 7.29 and 8.47 U/g. The effect of 10-ODA was similar in liquid culture as in solid culture. But the enzyme activities were lower in solid culture. From the result above, we can reduce the culturing time and increase production by applying 10-ODA for submerged culture of mushroom mycelium and bottle cultivation. On the other hand, if 10-ODA was applied to culture of Aspergillus spp., it could not only promote the growth of the mycelium but also increase the activities of the major enzymes. If we apply 10-ODA on the fermentary industry, we can have high enzyme activity of Aspergillus spp. and shorten the fermentary time. It is more economical and benef icial for development on the food fermentary industry.
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Lin, Li-Hua, and 林黎華. "Investigation and utilization of the secondary metabolite Terrein from Aspergillus terreus to suppress the growth of drug-resistant breast cancer stem/initiating cells." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/c6x82z.
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碩士國立臺灣大學
生化科學研究所
98
Recent studies have demonstrated there are cancer stem/initiating cells existed in breast cancer which display drug resistance to many conventional therapies and can cause cancer relapse. Therefore, the most promising strategy for breast cancer therapeutics is to develop methods that can either suppress self-renewal expansion, inhibit the function of multidrug transporters, or to induce apoptosis on cancer stem/initiating cells. Cancer stem/initiating cells expressed ABC transporters such as MDR1, MRP3 and ABCG2 that can efflux anticancer drugs such as mitoxanthrone, gemcitabine, doxorubicin or 5-fluorouracil. ABCG2, belongs to the ATP-binding cassette transporter (ABC) subfamily G, expressed in wide variety of stem cells and cancer stem cells. In fact, ABCG2, also named as breast cancer resistance protein (BCRP), was first discovered from a doxorubicin-resistant MCF-7 breast cancer cell line. ABCG2 is a Hoechst 33342 dye efflux pump that mediates side-population phenotype and also regulates porphyrin homeostasis in stem cells. It has been proposed that ABCG2 not only functions as a xenobiotic pump, but also affect cell metabolsm and self-renewal ability of stem cells and cancer stem cells. Terrein is a fungal metabolite and was first isolated from Aspergillus terreus. However, relatively little is known about Terrein. The aim of the current work is to determine if Terrein can serve as a potential compound that can target drug-resistant breast cancer initiating cells. In the current work, we used Taxol, the most effective drug for breast cancer, as a comparison. We found for the first time that low concentration of Terrein (1 nM) was sufficient to suppress the expansion of MCF-7 cells. The suppressive effect was either mediated by induction of apoptosis and cause of cell arrest at the G2M phase. We also revealed treatment of Terrein inhibited side-population and protoporphyrin IX (PPIX) efflux which may lead to suppression of the activity of breast cancer stem/initiating cells. In conclusion, Terrein displayed cytotoxicity against drug-resistant breast cancer cells. Moreover, the current work also indicates that Terrein is a potent inhibitor for ABCG2 transporter which can possibly lead to reduction in the activity of cancer stem/initiating cells. We therefore assume Terrein can possibly used as a therapeutics for breast cancer stem cells.
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Pan, Yong-Li, and 潘永歷. "Identification of Pathogenic Aspergillus and Candida Species at the Early Growth Stages by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry and Raman Spectroscopy." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/26125678559986105863.
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Wang, Chih-Li. "Assessing the Roles of Striatin Orthologs in Fungal Morphogenesis, Sexual Development and Pathogenicity." Thesis, 2011. http://hdl.handle.net/1969.1/ETD-TAMU-2011-08-9935.
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Striatin family proteins contain a caveolin binding domain, a coiled-coil motif, a calmodulin binding domain, and a WD-repeat domain. Homologs of striatin protein have been However, our knowledge of the function and the molecular mechanism of fungal striatin homologs is limited. Based on the conserved sequences of functional domains, I hypothesized that the fungal striatin orthologs also act as scaffolding proteins that are functionally conserved among fungal species and involved in multiple types of development in the diverse kingdom Mycota. I used reverse genetic strategies to study the function of the Aspergillus nidulans striatin ortholog (strA) and the Colletotrichum graminicola striatin ortholog (str1). In assays of sexual development, the strA deletion strain (ΔstrA) produces fewer ascospores with smaller cleistothecia, while the str1 deletion strain (Δstr1) is defective in perithecia development. The ΔstrA phenotypes indicate that StrA is associated with ascosporogenesis in cleistothecia. Both ΔstrA and Δstr1 are reduced in radial growth and in conidia production. The Δstr1 strain is also altered in its spiral growth pattern and morphology of conidia and hyphopodia, but it produces appressoria similar to wild type. The pairing of nitrate non-utilizing mutants demonstrates that Str1 is required for hyphal fusion. In pathogenicity, Δstr1 is less virulent in maize anthracnose leaf blight and stalk rot. The phenotypes of Δstr1 are complemented by the Fusarium verticillioides striatin ortholog (fsr1), indicating that Fsr1 and Str1 are functionally conserved. Over-expression of StrA reveals its positive role in conidiation and the sexual production. StrA::eGFP localizes mainly to the endoplasmic reticulum. After comparing the results from these two species and other studied fungal species, I suggest that fungal striatins are involved in five types of development including hyphal growth, hyphal fusion, conidiation, sexual development, and virulence, and propose a model of fungal striatin protein interactions to account for these diverse phenotypes.