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Aspergillus Niger (aspergillus + niger)
Kinds of Aspergillus Niger Selected AbstractsAspergillus niger Aortitis after Aortic Valve Replacement Diagnosed by Transesophageal EchocardiographyECHOCARDIOGRAPHY, Issue 5 2006Hamza Duygu M.D. Aspergillus aortitis following cardiac surgery has an important role among the cardiac infections as almost all affected cases result in death. Survival of the patient with Aspergillus aortitis is dependent on early initiation of aggressive medical and surgical treatment. Transesophageal echocardiography proved very useful in the diagnosis of this uncommon case of aortitis. In this paper, we present a patient with aortitis caused by Aspergillus niger that hasn't been reported previously diagnosed by transesophageal echocardiography following cardiac surgery. [source] Investigations of the Morphogenesis of Filamentous Microorganisms,ENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 5 2006S. Kelly Abstract Several biotechnological production processes are based on the cultivation of filamentous microorganisms like the fungus Aspergillus niger. The morphological development plays an important role for transport phenomena and the related productivity. The description of filamentous morphogenesis of A. niger as a model organism, given here, is structured in three morphological growth processes, a very fast conidial aggregation, followed by a second slower aggregation step promoted by germination and hyphal tip growth, and the growth of pellets as the last process. [source] Properties of pyranose dehydrogenase purified from the litter-degrading fungus Agaricus xanthodermaFEBS JOURNAL, Issue 3 2007Magdalena Kujawa We purified an extracellular pyranose dehydrogenase (PDH) from the basidiomycete fungus Agaricus xanthoderma using ammonium sulfate fractionation and ion-exchange and hydrophobic interaction chromatography. The native enzyme is a monomeric glycoprotein (5% carbohydrate) containing a covalently bound FAD as its prosthetic group. The PDH polypeptide consists of 575 amino acids and has a molecular mass of 65 400 Da as determined by MALDI MS. On the basis of the primary structure of the mature protein, PDH is a member of the glucose,methanol,choline oxidoreductase family. We constructed a homology model of PDH using the 3D structure of glucose oxidase from Aspergillus niger as a template. This model suggests a novel type of bi-covalent flavinylation in PDH, 9- S -cysteinyl, 8-,- N3-histidyl FAD. The enzyme exhibits a broad sugar substrate tolerance, oxidizing structurally different aldopyranoses including monosaccharides and oligosaccharides as well as glycosides. Its preferred electron donor substrates are d -glucose, d -galactose, l -arabinose, and d -xylose. As shown by in situ NMR analysis, d -glucose and d -galactose are both oxidized at positions C2 and C3, yielding the corresponding didehydroaldoses (diketoaldoses) as the final reaction products. PDH shows no detectable activity with oxygen, and its reactivity towards electron acceptors is rather limited, reducing various substituted benzoquinones and complexed metal ions. The azino-bis-(3-ethylbenzthiazolin-6-sulfonic acid) cation radical and the ferricenium ion are the best electron acceptors, as judged by the catalytic efficiencies (kcat/Km). The enzyme may play a role in lignocellulose degradation. [source] Intracellular pH homeostasis in the filamentous fungus Aspergillus nigerFEBS JOURNAL, Issue 14 2002Stephan J. A. Hesse Intracellular pH homeostasis in the filamentous fungus Aspergillus niger was measured in real time by 31P NMR during perfusion in the NMR tube of fungal biomass immobilized in Ca2+ -alginate beads. The fungus maintained constant cytoplasmic pH (pHcyt) and vacuolar pH (pHvac) values of 7.6 and 6.2, respectively, when the extracellular pH (pHex) was varied between 1.5 and 7.0 in the presence of citrate. Intracellular metabolism did not collapse until a ,pH over the cytoplasmic membrane of 6.6,6.7 was reached (pHex 0.7,0.8). Maintenance of these large pH differences was possible without increased respiration compared to pHex 5.8. Perfusion in the presence of various hexoses and pentoses (pHex 5.8) revealed that the magnitude of ,pH values over the cytoplasmic and vacuolar membrane could be linked to the carbon catabolite repressing properties of the carbon source. Also, larger ,pH values coincided with a higher degree of respiration and increased accumulation of polyphosphate. Addition of protonophore (carbonyl cyanide m -chlorophenylhydrazone, CCCP) to the perfusion buffer led to decreased ATP levels, increased respiration and a partial (1 µm CCCP), transient (2 µm CCCP) or permanent (10 µm CCCP) collapse of the vacuolar membrane ,pH. Nonlethal levels of the metabolic inhibitor azide (N3,, 0.1 mm) caused a transient decrease in pHcyt that was closely paralleled by a transient vacuolar acidification. Vacuolar H+ influx in response to cytoplasmic acidification, also observed during extreme medium acidification, indicates a role in pH homeostasis for this organelle. Finally, 31P NMR spectra of citric acid producing A. niger mycelium showed that despite a combination of low pHex (1.8) and a high acid-secreting capacity, pHcyt and pHvac values were still well maintained (pH 7.5 and 6.4, respectively). [source] Composition and antimicrobial activity of the essential oil of Micromeria cristata and Micromeria julianaFLAVOUR AND FRAGRANCE JOURNAL, Issue 1 2006Gordana Stojanovi Abstract The chemical composition of the essential oil of Micromeria cristata and Micromeria juliana was determined by GC-MS analysis. Among the 36 identified compounds of the M. cristata essential oil, isoborneol (11.3%), borneol (8.5%), verbenone (8.2%), 10- epi - , -cadinol and thujan-3-ol, were found to be major components. The main constituents of the M. juliana oil were verbenol (11.8%), thymol (10.8%), caryophyllene oxide (10.5%), borneol (9.3%) and myrtenal (7.1%). The in-vitro antimicrobial activity of the ethanolic solution of the essential oils was investigated by the disk diffusion method with ampicillin as the standard antibiotic against six microorganisms (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Salmonella enteritidis and Aspergillus niger). At 1:20 dilution the activity of both oils was moderate while at 1:40 dilution the oils showed weak or no activity. Copyright © 2005 John Wiley & Sons, Ltd. [source] Synthesis of N -Substituted (3S,4S)- and (3R,4R)-Pyrrolidine-3,4-diols: Search for New Glycosidase InhibitorsHELVETICA CHIMICA ACTA, Issue 12 2004Robert N -Substituted (3S,4S)- and (3R,4R)-pyrrolidine-3,4-diols 9 and 10, respectively, were derived from (+)- L - and (,)- D -tartaric acid, respectively. Compounds 9k, 9l, and 9m with the N -substituents, BnNH(CH2)2, 4-PhC6H4CH2NH(CH2)2 and 4-ClC6H4CH2NH(CH2)2, respectively, showed modest inhibitory activities toward , - D -amyloglucosidases from Aspergillus niger and from Rhizopus mold (Table,1). Unexpectedly, several (3R,4R)-pyrrolidine-3,4-diols 10 showed inhibitory activities toward , - D -mannosidases from almonds and from jack bean (Table,3). N -Substitution by the NH2(CH2)2 group, i.e., 10g, led to the highest potency. [source] Synthesis of Monosaccharide-Derived Spirocyclic Cyclopropylamines and Their Evaluation as Glycosidase InhibitorsHELVETICA CHIMICA ACTA, Issue 9 2003Christian Blüchel The glucose-, mannose-, and galactose-derived spirocyclic cyclopropylammonium chlorides 1a,1d, 2a,2d and 3a,3d were prepared as potential glycosidase inhibitors. Cyclopropanation of the diazirine 5 with ethyl acrylate led in 71% yield to a 4,:,5,:,1,:,20 mixture of the ethyl cyclopropanecarboxylates 7a,7d, while the Cu-catalysed cycloaddition of ethyl diazoacetate to the exo -glycal 6 afforded 7a,7d (6,:,2,:,5,:,3) in 93,98% yield (Scheme,1). Saponification, Curtius degradation, and subsequent addition of BnOH or t- BuOH led in 60,80% overall yield to the Z- or Boc-carbamates 11a,11d and 12a,12d, respectively. Hydrogenolysis of 11a,11d afforded 1a,1d, while 12a,12d was debenzylated to 13a,13d prior to acidic cleavage of the N -Boc group. The manno - and galacto -isomers 2a,2d and 3a,3d, respectively, were similarly obtained in comparable yields (Schemes,2 and 4). Also prepared were the differentially protected manno- configured esters 24a,24d; they are intermediates for the synthesis of analogous N -acetylglucosamine-derived cyclopropanes (Scheme,3). The cyclopropylammonium chlorides 1a,1d, 2a,2d and 3a,3d are very weak inhibitors of several glycosidases (Tables,1 and 2). Traces of Pd compounds, however, generated upon catalytic debenzylation, proved to be strong inhibitors. PdCl is, indeed, a reversible, micromolar inhibitor for the ,- glucosidases from C. saccharolyticum and sweet almonds (non-competitive), the , -galactosidases from bovine liver and from E. coli (both non-competitive), the , -galactosidase from Aspergillus niger (competitive), and an irreversible inhibitor of the , -glucosidase from yeast and the , -galactosidase from coffee beans. The cyclopropylamines derived from 1a,1d or 3a,3d significantly enhance the inhibition of the ,- glucosidase from C. saccharolyticum by PdCl, lowering the Ki value from 40,,M (PdCl) to 0.5,,M for a 1,:,1 mixture of PdCl and 1d. A similar effect is shown by cyclopropylamine, but not by several other amines. [source] Development of a natural preservative system using the mixture of chitosan- Inula helenium L. extractINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 4 2002S.-B. Seo Synopsis The aim of this study was to develop a new natural preservative system making up for the weak points of chitosan as a preservative. As reported in a previous manuscript (20th IFSCC Congress, Cannes, France, 1998), the minimum inhibitory concentrations (MICs) of water-soluble chitosan against bacteria and yeast were 0.9,3.0 mg mL,1, whereas MICs of chitosan against Aspergillus niger were over 5.0 mg mL,1. However, the result of recent study showed that the MICs of Inula helenium L. extract against A. niger were below 1.0 mg mL,1. Thus, we could develop a new preservative system containing both chitosan and I. helenium L. extract named CI-mixture. MICs of CI-mixture against bacteria and fungi (yeast and mould) were 2.0,4.0 mg mL,1. When 10.0% of the mixture (the ratio of chitosan to I. helenium L. extract = 7.5% : 2.5%) was applied to cosmetic formulae such as skin lotion, milk lotion, cream and pack, it revealed appropriate preservative efficacy. Our result of the patch test also showed that this preservative system reduced skin irritation by about 30,50%, as compared to the organic preservative system. Therefore, the good natural preservative system including chitosan and Inula helenium L. extract could be incorporated in cosmetic formulations. Résumé Le but de cette étude était de développer un nouveau système conservateur naturel en améliorant les propriétés du chitosan en tant que conservateur. Comme décrit dans un manuscrit précédent (20ième Congrès IFSCC Cannes, France, 1998), les C.M.I (concentrations minimales inhibitrices) du chitosan hydro-soluble contre les bactéries et levures étaient de 0.9,3 mg mL,1 et supérieures à 5 mg mL,1 conte A. niger. Cependant, des résultats récents conféraient à un extrait d' Inula helenium L. des CMI contre A niger inférieures à 1 mg mL,1. Ainsi, il devenait possible de développer un système conservateur combinant ces deux composés (chitosan et I. helenium L.) dénommé ici mélange CI. Les CMI du mélange CI contre les bactéries et champignons (levures et moisissures) étaient de 2,4 mg mL,1. Lorsque ce mélange CI (rapport chitosan/Inula = 7.5% : 2.5%) était introduit à 10% dans des formules cosmétiques telles que lotion cutanée, lait cutané, crème. il montrait de bonnes propriétés conservatrices. Des résultats de patch tests cutanés montraient aussi que ce système conservateur réduisait l'irritation cutanée d'environ 30à 50% par rapport à un système conservateur organique. Le système de conservateur naturel optimal contenant le chitosan et l'extrait d'I. helenium L. peut ainsi être incorporé dans les formulations cosmétiques [source] Moisture sorption isotherm and xerophilic moulds associated with dried cocoyam chips in storage in NigeriaINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 5 2008J. Obeta Ugwuanyi Summary Extended storage of cocoyams (Colocasia antiquorum and Colocasia esculenta) is achieved in parts of Nigeria by processing them into smoked and dried chips. In this study, cocoyam chips were collected from parts of Nigeria at the end of drying, at various periods of storage and from markets, and analysed for moisture content, moisture sorption characteristics and xerophilic moulds. Moisture content of chips ranged from 7.07 ± 1.1% for freshly dried samples to 16 ± 2.2% for samples stored up to 8 months. Six mould species from four groups of the genus Aspergillus (including five xerophiles) identified as Aspergillus fumigatus, Eurotium repens, Eurotium amstelodami, Eurotium chevalieri and Aspergillus flavus and Aspergillus niger and Mucor sp. were isolated. The variety of moulds increased with storage and moisture content of samples. Moisture sorption in dried chips showed type II sigmoidal behaviour. Wood smoke significantly protected chips from mould colonization, but in cooperation with reduced water activity. Simple and inexpensive storage of freshly dried samples in airtight bags led to prolonged storage of up to 14 months without deterioration. [source] Antimicrobial efficiency of titanium dioxide-coated surfacesJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2010P. Muranyi Abstract Aims:, Development and evaluation of an antimicrobially active titanium dioxide coating. Methods and results:, For this purpose, titanium dioxide coatings were applied to glass slides by using a sol-gel method and then exposed to a light source. The antimicrobial efficiency was determined by a count reduction test for selected test strains (Aspergillus niger, Bacillus atrophaeus, Kocuria rhizophila), which were homogenously sprayed onto surface. The bacterial count of K. rhizophila was reduced by up to 3·3 log10 on titanium dioxide samples within 4 h of UV-A light exposure. Experiments with spore formers did not lead to any significant log reduction. A further aspect of this work was to evaluate the effect of selected parameters (relative humidity, inoculation density, radiation intensity) on the antimicrobial efficiency to gain knowledge for further optimization procedures. At a high relative humidity (85% r.h.), increased inactivation was observed for K. rhizophila (up to 5·2 log10). Furthermore, a dependency of the antimicrobial effect on the radiation intensity and the inoculation density was identified. Conclusions:, Antimicrobial surfaces and coatings based on titanium dioxide have the potential to effectively inactivate vegetative micro-organisms. Significance and impact of the study:, Knowledge about the antimicrobial efficiency of titanium dioxide was gained. This is a prerequisite for industrial applications to improve hygiene, food quality and safety. [source] Influence of relative gas humidity on the inactivation efficiency of a low temperature gas plasmaJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2008P. Muranyi Abstract Aims:, To investigate the effect of relative gas humidity on the inactivation efficiency of a cascaded dielectric barrier discharge (CDBD) in air against Aspergillus niger and Bacillus subtilis spores on PET foils. Methods and Results:, The inactivation kinetics as a function of treatment time were determined using synthetic air with different relative humidity as the process gas. Spores of A. niger and B. subtilis respectively were evenly sprayed on PET foils for use as bioindicators. In the case of A. niger, increased spore mortality was found at a high relative gas humidity of 70% (approx. 2 log10). This effect was more evident at prolonged treatment times. In contrast, B. subtilis showed slightly poorer inactivation at high gas humidity. Conclusions:, Water molecules in the process gas significantly affect the inactivation efficiency of CDBD in air. Significance and Impact of the Study:, Modifying simple process parameters such as the relative gas humidity can be used to optimize plasma treatment to improve inactivation of resistant micro-organisms such as conidiospores of A. niger. [source] pH Control of the production of recombinant glucose oxidase in Aspergillus nidulansJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2004R. Luque Abstract Aims:, Recombinant Aspergillus nidulans sVAL040, capable of synthesizing and secreting glucose oxidase derived from Aspergillus niger was used to study the influence of pH and carbon source on enzyme production. Methods and Results:, Glucose oxidase gene (goxC) was expressed under transcriptional regulation by using the promoter of A. nidulans xlnB gene (encoding an acidic xylanase). A maximum specific glucose oxidase activity of approx. 10 U mg,1 protein and a maximum volumetric productivity of 29·9 U l,1 h,1 were obtained at pH 5·5, after 80 h of growth by using xylose as inducer. Enzyme volumetric productivity increased when xylans were used instead of xylose; however, specific glucose oxidase activity did not differ significantly. Conclusions:, Specific GOX activity obtained at pH 5·5 are two to three times more than those previously described for goxC multicopy transformants of A. nidulans. Xylans were a more powerful inducer than xylose although fungal growth was lower when the polymers were used. Significance and Impact of the Study:, The obtained results by using xlnB promoter in A. nidulans could be useful in improving heterologous enzyme production by using genetic- and process-engineering strategies. [source] Survival of spores of Rhizopus stolonifer, Aspergillus niger, Botrytis cinerea and Alternaria alternata after exposure to ethanol solutions at various temperaturesJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2004F. Mlikota Gabler Abstract Aims:, To quantify and model the toxicity of brief exposures of spores of Rhizopus stolonifer, Aspergillus niger, Botrytis cinerea and Alternaria alternata to heated, aqueous ethanol solutions. These fungi are common postharvest decay pathogens of fresh grapes and other produce. Sanitation of produce reduces postharvest losses caused by these and other pathogens. Methods and Results:, Spores of the fungi were exposed to solutions containing up to 30% (v/v) ethanol at 25,50°C for 30 s, then their survival was determined by germination on semisolid media. Logistical, second-order surface-response models were prepared for each fungus. Subinhibitory ethanol concentrations at ambient temperatures became inhibitory when heated at temperatures much lower than those that cause thermal destruction of the spores by water alone. At 40°C, the estimated ethanol concentrations that inhibited the germination of 50% (LD50) of the spores of B. cinerea, A. alternata, A. niger and R. stolonifer were 9·7, 13·5, 19·6 and 20·6%, respectively. Conclusions:, Ethanol and heat combinations were synergistic. Control of spores of these fungi could be accomplished with much lower temperatures and ethanol concentrations when combined compared with either used alone. Botrytis cinerea and A. alternata were less resistant to the combination than A. niger or R. stolonifer. [source] Nanocrystallite regions of guar gum filled PU/PAN composites before and after biodegradation using WAXSJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008H. Kumar Abstract Polyurethane/polyacrylonitrile semi-interpenetrating polymer network containing varying weight percent of guar gum were prepared. The resulting composites were subjected to biodegradation with the help of specific fungi Aspergillus niger. The composite before and after biodegradation were subjected to wide angle X-ray scattering studies. The nanocrystallite regions, area, and size are determined from X-ray data using three different asymmetric column length functions. A comparison of these parameters does explain the nature of biodegradation at microlevel. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Erratum: J. Basic Microbiol.JOURNAL OF BASIC MICROBIOLOGY, Issue 4 20094/200 As came to our knowledge, the evidence for a new spiroketal produced by Aspergillus niger isolated from an opuntia by Wu et al. (Journal of Basic Microbiology 2008, 48 (2008), 140,142; DOI 10.1002/jobm.200700363) does not preclude identity with a previously published compound from Aspergillus niger, terrineol (Macedo Jr., F.C. et al., Tetrahedron Lett., 45 (2004), 53, and Macedo Jr., F.C. et al., Magn. Reson. Chem., 43 (2005), 251). The authors failed to discuss this possibility (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Purification and characterization of tannin acyl hydrolase from Aspergillus niger MTCC 2425JOURNAL OF BASIC MICROBIOLOGY, Issue 6 2003Rita Bhardwaj The present investigation was carried out for increasing the yield of tannase of Aspergillus niger and the physico-chemical characterization of this enzyme. Homogenization and detergent pretreatments did not have any remarkable effect on the extraction of enzyme protein. However, extraction of fungal pigments and proteins was observed to have high pH dependence, and maximum enzyme extraction was obtained at pH 5.5. The two-step purification protocol gave 51-fold purified enzyme with a yield of 20%. The total tannase activity was made up of nearly equal activity of esterase and depsidase. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis of purified tannase protein indicated it to be made up of two polypeptides of molecular weight 102 and 83 kDa. Based on the Michaelis-Menten constant (Km) of tannase for three substrates tested, tannic acid was the best substrate with Km of 2.8 × 10,4M, followed by methyl gallate and propyl gallate. The inhibition was maximum for CaCl2 (58%) whereas EDTA had no modulatory effect on tannase activity. The inhibitor binding constant (KI) of CaCl2 was 5.9 × 10,4M and the inhibition was of noncompetitive type. [source] Production of ,-galactosidase from recombinant Saccharomyces cerevisiae grown on lactoseJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 8 2004Lucília Domingues Abstract Improved productivity and costs reduction in fermentation processes may be attained by using flocculating cell cultures. The production of extracellular heterologous ,-galactosidase by recombinant flocculating Saccharomyces cerevisiae cells, expressing the lacA gene (coding for ,-galactosidase) of Aspergillus niger under the ADHI promotor and terminator in a bioreactor was studied. The effects of lactose concentration and yeast extract concentration on ,-galactosidase production in a semi-synthetic medium were analysed. The extracellular ,-galactosidase activity increased linearly with increasing initial lactose concentrations (5,150 g dm,3). ,-Galactosidase production also increased with increased yeast extract concentration. During the entire fermentation, no accumulation of the hydrolysed sugars, glucose and galactose, was observed. The catabolic repression of the recombinant strain when cultured in a medium containing equal amounts of glucose and galactose was confirmed. In complete anaerobiosis, the fermentation of lactose resulted in a very slow fermentation pattern with lower levels of ,-galactosidase activity. The bioreactor operation together with optimisation of culture conditions (lactose and yeast extract concentration) led to a 21-fold increase in the extracellular ,-galactosidase activity produced when compared with preliminary Erlenmeyer fermentations. Copyright © 2004 Society of Chemical Industry [source] Bioleaching of copper and other metals from low-grade oxidized mining ores by Aspergillus nigerJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 5 2003Catherine N Mulligan Abstract A study was initiated to determine the feasibility of using the fungus Aspergillus niger for bioleaching metals from oxide low-grade ore. Large quantities of the metals are embodied in the low-grade ores and mining residues that can be recovered. Presently available techniques (pyrometallurgical and hydrometallurgical) are expensive or may have a negative impact on the environment. An oxidized mining ore containing mainly copper (7245 mg kg,1 residue) was studied. In this study, the fungus A niger produced a variety of organic acids. Addition of small quantities of sulfuric acid enhanced the organic acids, efficiency. Various agricultural wastes were evaluated as substrates and a maximum solubilization of 68% for copper for a medium containing potato peels was achieved. In conclusion, leaching of copper from a mining ore is technically feasible using A niger. Further research must be performed to increase the rate of copper removal. Copyright © 2003 Society of Chemical Industry [source] SHELF LIFE OF FRESH NOODLES AS AFFECTED BY THE FOOD GRADE MONOLAURIN MICROEMULSION SYSTEMJOURNAL OF FOOD PROCESS ENGINEERING, Issue 5 2008XIAOWEI FU ABSTRACT Food grade monolaurin (the glycerol monoester of lauric acid) microemulsions (MMEs) based on multicomponent mixtures and the effects of MMEs on the shelf life of fresh noodles were studied. A microemulsion system consisting of monolaurin (M), surfactants (Tween 20 and Tween 80, Wenzhou Qingming Chemical Engineering Company, Wenzhou, Zhejiang, China ) and cosurfactant (pentanol and dodecanol) dispersed in distilled water was used. The influence of surfactants on the phase behavior was studied in this article. Subsequently, two MMEs with large oil in water regions have demonstrated the enhanced antimicrobial activities against Bacillus subtilis, Escherichia coli, Aspergillus niger and Penicillium digitatum, compared to monolaurin (M) alone. In addition, the shelf life of fresh noodles prepared with monolaurin (M) alone was about 4 days, whereas MMEs extended shelf life by 10 days at least when stored at 37C. PRACTICAL APPLICATIONS The effect of monolaurin microemulsion (MME) as antimicrobial agents in foods, especially those neutral foods such as noodles, is obvious, and MME has demonstrated a much longer shelf life of fresh noodles than M alone. In addition, for those neutral foods other than fresh noodles, the application of MMEs can also be studied. [source] CHEMICAL CHARACTERIZATION AND ANTIFUNGAL ACTIVITY OF ORIGANUM ONITES L. ESSENTIAL OILS AND EXTRACTSJOURNAL OF FOOD SAFETY, Issue 1 2009MIHRIBAN KORUKLUOGLU ABSTRACT Essential oils (EOs) and extracts (methanol, acetone and diethyl ether) of fresh and dried oregano (Origanum onites L.) were used to determine the antifungal effect on Alternaria alternata, Aspergillus flavus (two strains), Aspergillus niger (two strains), Aspergillus parasiticus, Fusarium semitectum, Fusarium oxysporum, Mucor racemosus and Penicillium roqueforti by disk diffusion methods. Minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of all samples were determined. The antifungal activity of the fresh herb was greater than that of the dried herb. MIC values for fresh and dried methanol extracts were 150,950 µg/mL and 750,950 µg/mL, respectively. MFC values for methanol extracts were determined between 300 and 1200 µg/mL for fresh oregano and between 750 and 1100 µg/mL for dried oregano. The EOs of fresh and dried oregano totally inhibited test fungi. EOs produced the lowest MIC and MFC values: 8.5 µg/mL and 9.0 µg/mL, respectively (P < 0.005). The highest extract activity was exhibited by fresh oregano against A. alternata (24 mm) followed by P. roqueforti (20 mm). The greatest total antifungal effect was observed from methanol extracts. The chemical composition of fresh oregano EO and extracts was examined using gas chromatography-mass spectrometry (GC-MS). Over 80 volatiles were detected, of which 42 were positively identified by matching both MS fragmentation patterns with standardized retention characteristics. p-Cymene, thymol and carvacrol were the most prominent, followed by ,-pinene, camphor and borneol. PRACTICAL APPLICATIONS In the past decade interest in natural antimicrobial plant extracts has been growing. Various plants have historically been used for the purposes of food preservation and flavor enhancement as well as medicinal purposes. An example is oregano, the leafy part of the plant belonging to the Labiatae family. It has been used to improve the flavor and the organoleptic properties of many foods from numerous cultures. It has also been used to prolong the storage life of foods probably because of antifungal properties. The preservative nature of fresh oregano has been employed in many food applications, including meat and fish products, as well as in pharmaceuticals, alternative medicines and natural therapies. [source] CONTAMINATION OF GRAINS BY MYCOTOXIN-PRODUCING MOLDS AND MYCOTOXINS AND CONTROL BY GAMMA IRRADIATIONJOURNAL OF FOOD SAFETY, Issue 3 2006NAGY H. AZIZ ABSTRACT Ninety random grain samples were collected and analyzed for mycotoxins, and the effect of gamma irradiation on the production of mycotoxins in grains was studied. Aspergillus, Penicillium, Mucor, Rhizopus, Fusarium, Alternaria, Scopulariopsis and Cladosporium were the most common fungal genera isolated from grains. Aspergillus flavus, Aspergillus niger, Aspergillus candidus, Aspergillus ochraceus, Penicillium citrinum, Penicillium expansum, Penicillium citreonigrum, Penicillium purpurogenum, Penicillium griseofulvum and Penicillium verrucosumwere the most common Aspergillus and Penicillium species in grains. Out of 120 Aspergillus and Penicillium isolates, 80 were mycotoxin producers. Analysis of grains revealed the occurrence of aflatoxin B1 ochratoxin A, cycolopiazonic acid and citrinin. Of the 90 samples, 67 were positive for one or more mycotoxin. Irradiation of grains at dose of 2.0 and 4.0 kGy decreased significantly the total fungal counts compared with unirradiated controls. After 100 days of storage at room temperature, the unirradiated grains were contaminated with high concentrations of mycotoxins as compared with irradiated 4.0-kGy samples. Mycotoxin production in grains decreased with increasing irradiation doses and was not detected at 6.0 kGy over 100 days of storage. [source] Promising antimicrobial agents: Synthetic approaches to novel tricyclic and tetracyclic pyrimidinones with antimicrobial propertiesJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 5 2010Hatem M. Gaber New tricyclic pyrimidinone derivatives were obtained from the corresponding thiazolopyrimidinone or hydrazino systems. The annelation of tricyclic hydrazino compound with 1,2,4-triazole and tetrazole moieties gave novel tetracyclic condensed pyrimidinones. The investigation of the antimicrobial properties of tricyclic and tetracyclic pyrimidinones, by agar-well diffusion assay, was carried out against six pathogenic bacteria (Bacillus cereus, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Klebsiella spp, and Salmonella typhyrium) and four pathogenic fungi (Aspergillus flavus, Aspergillus niger, Aspergillus fumigatus, and Trichderma horozianum). Most of the compounds tested exhibited some degree of antimicrobial activity against microorganisms. Among these compounds, 4-benzylidenhydrazino-8-cyano-7-(furan-2-yl)thiazolo[3,2- a:4,5- d,]dipyrimidin-9-one (12) showed the most favorable antibacterial activity, while compound 17 showed the highest effect on fungi. Interestingly, tetrazole derivative 19 displayed a remarkable effect on fungi much more than the corresponding 3-substituted triazole derivatives on the one hand, whereas the lowest effect on bacteria on the other. J. Heterocyclic Chem., (2010). [source] Synthesis and antimicrobial activity of novel 2-alkyl/arylcarbamato-6-(1,1-dimethylethyl)-3-cyclohexyl-3,4-dihydro-2H -1,3,2-benzoxazaphosphorine-2-oxidesJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 5 2002Y. Hari Babu Novel 2-alkyl/arylcarbamato-6-(1,1-dimethylethyl)-3-cyclohexyl-3,4-dihydro-2H -1,3,2-benzoxaza-phosphorine-2-oxides (IV) have been synthesized from reactions of 2-cyclohexylaminomethyl-4- t -butylphenol I [8c] with various dichlorophosphinyl carbamates (III) [8a-b] in dry toluene in the presence of triethylamine at 40-50 °C. All the title compounds (IVa-j) at reflux temperature are degraded to 2-amino-6-(1,1-dimethylethyl)-3-cyclohexyl-3,4-dihydro-2H -1,3,2-benzoxazaphosphorine-2-oxide (IVk) exclusively. The structures are determined by ir, nmr and mass spectral studies. They were screened for antifungal activity against Penicillium notatum, Aspergillus niger and Helminthosporium sps, and antibacterial activity on Escherchia coli, Staphylococcus aureus and Pseudomonas aeruginosa. A few of them possess significant activity. [source] Synthesis and antimicrobial activity of 2-substituted-2,3-dihydro-5-propoxy-1H -1,3,2-benzodiazaphosphole 2-OxidesJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 1 2001M. Venugopal Several 2-alkylcarbamato/thiocarbamato/aryloxy/trichloromethyl-2,3-dihydro-5-propoxy-1H -1,3,2-benzodiazaphosphole 2-oxides (4 and 6) were synthesised by reacting 4-propoxy- o -phenylenediamine (1) with various N -dichlorophosphinyl carbamates (3), aryl phosphorodichloridates (5a-f) and trichloromethyl phosphonic dichloride (5g) in the presence of triethylamine at 45-65 °C. Their ir, 1H, 13C, 31P nmr and mass spectral data are discussed. The compounds were screened for antifungal activity against Curvularia lunata and Aspergillus niger and for antibacterial activity against Bacillus subtilis and Escherichia coli. Most of these compounds exhibited moderate activity in the assays. [source] Development of a Sensitive Serological Method for Specific Detection of Latent Infection of Macrophomina phaseolina in CowpeaJOURNAL OF PHYTOPATHOLOGY, Issue 1 2009Leonard Afouda Abstract A double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) was developed for the specific detection and quantification of Macrophomina phaseolina in plant tissue. Both polyclonal antisera produced against immunogens from mycelium and culture filtrate of M. phaseolina detected the fungus in mycelial and plant extracts, although the antibodies raised against mycelium were more sensitive. No cross-reaction occurred with Rhizopus stolonifer, Pythium ultimum, Mucor hiemalis, Fusarium oxysporum, Septoria nodorum, Rhizoctonia solani, Sclerotinia sclerotiorum, Phytophthora infestans and Aspergillus niger. In enzyme assays, activity of the endo-acting hydrolytic enzymes 1,3-,-glucanase and, less, cellulase, but not xylanase was detected in infected plants. DAS-ELISA was more sensitive than the 1,3-,-glucanase assay. In polyacrylamide gel electrophoresis (PAGE) up to 18 protein bands were observed, with four bands occurring in the 12 tested isolates deriving from various geographical origin in Niger and Nigeria. The enzyme assays and protein patterns were considered not suitable for specific M. phaseolina detection. Macrophomina phaseolina was essentially located in the roots and hypocotyls, and less in epicotyls and leaves of infected plants. The antibodies were also useful to detect latent infection and the infection of cowpea seeds. [source] The Effects of Oligosaccharide and Spores from Aspergillus niger on the Defence Responses of Taxus chinensis Leaves In vitroJOURNAL OF PHYTOPATHOLOGY, Issue 10 2003M. Y. Li Abstract Spores and oligosaccharide of a strain of Aspergillus niger, which had been isolated from the inner bark of Taxus chinensis, were used to treat T. chinensis leaves. The spores decreased the dry weight and chlorophyll content of the leaves, but increased their malondialdehyde content; oligosaccharide induced similar but more moderate changes. The changes in soluble protein, phenolic content, and peroxidase and phenylalanine ammonia-lyase activity were also analysed. Oligosaccharide significantly increased all these, whereas the spores had contrary effects. Results indicate that oligosaccharide, but not the fungal spores, elicited a defence reaction in T. chinensis. Possible reasons for these different effects on T. chinensis leaves in vitro are discussed. [source] Thienyl analogues of acyclic monoterpene alcohols and their biological activityJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 12 2009Rados, aw Bonikowski Abstract BACKGROUND: Thienyl analogues of linalool, geraniol, nerol and citronellol were synthesised and their sensory and anti- microbial activities were investigated. RESULTS: The thienyl analogues of linalool, geraniol, nerol and citronellol, in which the isobutenyl moiety was replaced by a thiophene substituent, were synthesised from commercially available 2- and 3-methylthiophenes and 2- and 3-thiophenecarboxaldehydes. The olfactory properties of the new compounds were generally of the corresponding parent terpene type; however, their relative volatility determined by the headspace gas chromatography method was lower by a factor of 34,42 compared with the parent alcohols. Antimicrobial activity against Aspergillus niger and Penicillium expansum of some thienyl analogues of linalool was 1.5,3 times higher than that of linalool, with a minimum inhibitory concentration of 0.2,0.1 µL mL,1. CONCLUSION: Replacement of the isobutenyl moiety in acyclic monoterpene alcohols by a thienyl substituent results in the formation of new terpene analogues, some of which are interesting for perfumery and cosmetology because of their odour quality, tenacity and antimicrobial action. Copyright © 2009 Society of Chemical Industry [source] Heterologous production of the Piromyces equi cinnamoyl esterase in Trichoderma reesei for biotechnological applicationsLETTERS IN APPLIED MICROBIOLOGY, Issue 6 2009L. Poidevin Abstract Aims:, The objective of the study was to produce and characterize the cinnamoyl esterase EstA from the anaerobic fungus Piromyces equi for potential industrial applications. Methods and Results:, The catalytic domain EstA was produced in Trichoderma reesei. Because the two fungi displayed different genome features, including different codon usage and GC content, a synthetic gene was designed and expressed, leading to the production of the corresponding protein at around 33 mg per litre in the T. reesei culture medium. After the recombinant protein was purified, biochemical characterization showed that EstA presents peak activity at pH 6·5 and at 50,60°C. Furthermore, EstA remained stable at pH 6,8 and below 50°C. EstA was compared to cinnamoyl esterases FaeA and FaeB from Aspergillus niger in terms of ferulic acid (FA) release from wheat bran (WB), maize bran (MB) and sugar beet pulp (SBP). Conclusion:, The synthetic gene was successfully cloned and overexpressed in T. reesei. EstA from P. equi was demonstrated to efficiently release FA from various natural substrates. Significance and Impact of the Study:, Recombinant EstA produced in an industrial enzyme producer, T. reesei, was biochemically characterized, and its capacity to release an aromatic compound (FA) for biotechnological applications was demonstrated. [source] Technical advance in fungal biotechnology: development of a miniaturized culture method and an automated high-throughput screeningLETTERS IN APPLIED MICROBIOLOGY, Issue 2 2009F. Alberto Abstract Aims:, The goal of the study was to develop a reliable, reproducible and rapid method of culture in order to screen a large number of fungal transformants. Methods and Results:, The method is based upon miniaturized cell cultures and automated expression screening in microwell plates. For the method development, 50 recombinant Aspergillus vadensis clones producing feruloyl esterase B (FaeB) from Aspergillus niger were screened in 6 days. Then a panel of clones showing various behaviours was checked in flasks in order to demonstrate the reproducibility of the method. Using this method, a transformant of A. vadensis producing 1·2 g l,1 of FaeB was selected (12-fold more than the A. niger overproducing strain). Conclusions:, This miniaturized culture method allows to obtain reliable and reproducible results. The procedure has the advantages of being efficient, time-saving and more efficient than conventional in-flask culture screening as it can screen 800 clones per day after a culture of 3 days. Significance and Impact of the Study:, This method could be applied to any other fungal strain culture, enzyme activity or biodiversity screening. [source] Effect of germicidal UVC light on fungi isolated from grapes and raisinsLETTERS IN APPLIED MICROBIOLOGY, Issue 3 2007A. Valero Abstract Aims:, To examine how UVC affects the different genera of fungi commonly isolated from grapes, with the aim of understanding changes in mycobiota during grape ripening and possible applications for preventing grape decay during storage. Methods and Results:, Spores of Aspergillus carbonarius, Aspergillus niger, Cladosporium herbarum, Penicillium janthinellum and Alternaria alternata (between 100,250 spores/plate agar) were UVC irradiated for 0 (control), 10, 20, 30, 60, 300 and 600 s. Plates were incubated at 25°C and colonies were counted daily up to 7 days. Alternaria alternata and Aspergillus carbonarius were the most resistant fungi. Conidial germination in these species was reduced by approx. 25% after 10 s of exposure, compared with greater than 70% reduction for the remaining species tested. Penicillium janthinellum spores were the most susceptible at this wavelength. UVC exposures of 300 s prevented growth of all isolates studied, except for Alternaria alternata. Conclusions:, UVC irradiation plays a major role in selecting for particular fungi that dominate the mycobiota of drying grapes. Significance and Impact of the Study:, The UVC irradiation of harvested grapes could prevent germination of contaminant fungi during storage or further dehydration. [source] | ||||||||||||||||||||||||||||||||||