Showing papers on "Aspergillus niger published in 1988"
TL;DR: Fructooligosaccharides could be more effectively prepared with a higher concentration of sucrose if use could be made of an enzyme having higher transfructosylating ability.
Abstract: The fructosyl transfer to sucrose was investigated, and Aspergillus niger ATCC 20611 was selected as the most suitable strain for fructooligosaccharide production. This strain showed very high enzyme productivity, and its transfructosylating activity was very strong compared to its hydrolyzing activity. Fructooligosaccharides could be more effectively prepared with a higher concentration of sucrose if use could be made of an enzyme having higher transfructosylating ability. Treatment of 50% (w/v) sucrose with the A. niger enzyme afforded a mixture of fructooligosaccharides with inulin-type structures of 1F(1-β-fructofuranosyl)n-sucrose (n = 1 to 3). The individual saccharides could be separated by the combination of a carbon column chromatography and preparative HPLC.
250 citations
TL;DR: Oxalate accumulation was induced in Aspergillus niger by shifting the pH from 6 to 8.1, indicating the biosynthesis of oxalate by hydrolytic cleavage of oxaloacetate, and this enzyme is located in the cytoplasm of A. niger.
Abstract: Oxalate accumulation of up to 8 g/liter was induced in Aspergillus niger by shifting the pH from 6 to 8. This required the presence of Pi and a nitrogen source and was inhibited by the protein synthesis inhibitor cycloheximide. Exogenously added 14CO2 was not incorporated into oxalate, but was incorporated into acetate and malate, thus indicating the biosynthesis of oxalate by hydrolytic cleavage of oxaloacetate. Inhibition of mitochondrial citrate metabolism by fluorocitrate did not significantly decrease the oxalate yield. The putative enzyme that was responsible for this was oxaloacetate hydrolase (EC 3.7.1.1), which was induced de novo during the pH shift. Subcellular fractionation of oxalic acid-forming mycelia of A. niger showed that this enzyme is located in the cytoplasm of A. niger. The results are consistent with a cytoplasmic pathway of oxalate formation which does not involve the tricarboxylic acid cycle.
158 citations
TL;DR: Three arabinan-degrading enzymes were isolated from a preparation derived from Aspergillus niger with optimum pH values in the range of 3·7 to 5·0 and their optimum temperatures 50 to 60°C.
142 citations
TL;DR: In this paper, a theoretical calculation based on the Ross equation showed that the water activity of the substrate decreased to 0.85 towards the end of the culture and increased when sugarcane bagasse was used as high water retention capacity support.
Abstract: During the solid state fermentation (SSF) of cassava starch by Aspergillus niger estimations were made of total water, consumed water and the residual water remaining in small quantities after 23 h. A theoretical calculation based on the Ross equation showed that the water activity (a
w) of the substrate decreased to 0.85 towards the end of the culture. Such low values were assumed to be inhibitory to growth. The a
w of the substrate was increased when sugarcane bagasse was used as a high water retention capacity support. Higher growth rates and substrate conversion to biomass were obtained with this system, confirming that water availability is a critical factor in the SSF of starch substrates.
121 citations
TL;DR: Solubilization of insouluble phosphate increased with fungal growth, reaching a maximum after 11 days of culture, and ammonium salts favoured the production of larger amounts of soluble phosphate than organic nitrogen, corresponding to the lowest pH and highest titratable acidity values obtained.
Abstract: In order to determine conditions that may provide greater solubilization of insouluble phosphate, the fungus Aspergillus niger was grown in a stationary culture containing modified citrate medium supplemented with 800 mg fluorapatite per litre. Solubilization of insouluble phosphate increased with fungal growth, reaching a maximum after 11 days of culture. Soluble phosphate levels were correlated with pH of the culture medium but not with titratable acidity values, probably due to the metabolic activity of the fungus resulting from consumption of sugar in the culture medium. Fructose, glucose, xylose, and sucrose were the carbohydrates that favoured fluorapatite solubilization the most when compared with galactose and maltose. Although increasing fructose concentrations in the culture medium favoured mycelial growth, increased total acidity and a fall in pH, soluble phosphate levels were reduced, probably owing to consumption by the rapidly growing fungus. Among the nitrogen sources tested, ammonium salts favoured the production of larger amounts of soluble phosphate than organic nitrogen (peptone or urea) or nitrate, corresponding to the lowest pH and highest titratable acidity values obtained.
88 citations
TL;DR: The growth kinetics of Aspergillus niger on a solid support, i.e., sugarcane bagasse, impregnated with a liquid glucose medium, were investigated under different culture conditions as mentioned in this paper.
78 citations
TL;DR: Inoculation methods and aeration conditions in the production of pellet cultures of Aspergillus niger 110 with acceptable citric acid yields were studied.
76 citations
69 citations
TL;DR: Seven samples of cross-linked co-polyesters of citric acid and glycerol from seven different mole ratios of the reactants have been synthesised as initially insoluble amorphous solids which become soluble in water within 8–10 days due to partial hydrolysis of the cross-links.
Abstract: Seven samples of cross-linked co-polyesters of citric acid and glycerol from seven different mole ratios of the reactants have been synthesised as initially insoluble amorphous solids which become soluble in water within 8–10 days due to partial hydrolysis of the cross-links. They have been characterised by their IR spectra, glass transition temperature and swelling behaviour. The acid to glycerol mole ratios 0.83 and 0.88 produce maximum cross-link density. Microbial degradation of the polymer samples in aqueous suspension has been studied using the fungus Aspergillus niger and the bacterium E. coli. All the polymer samples are degraded by Aspergillus niger and E. coli and the more cross-linked products have been found to be more degradable. The possible use of these cross-linked co-polyesters as matrices for controlled release of drugs has been illustrated.
62 citations
TL;DR: The cloning and sequencing of an Aspergillus niger gene encoding a secreted form of phosphate-repressible acid phosphatase by complementation of a pacA (phosphate-repressedible acidosphatase) mutant of AsperGillus nidulans is described.
59 citations
TL;DR: In this article, the transxylosyl reaction of Aspergillus niger IFO 6662 enzyme was used to synthesize β-Xylosides from xylobiose and water miscible alcohols.
Abstract: The enzymatic synthesis of alkyl β-xylosides from xylobiose and alcohols through the transxylosyl reaction of Aspergillus niger IFO 6662 enzyme was studied. Various alkyl β-xylosides were effectively synthesized from xylobiose and water miscible alcohols such as methanol, ethanol, 1-propanol and 2-propanol. The molar ratios of the products, respective β-xylosides and xylose, were approximately 1:1, indicating a theoretical yield for the transfer reaction. Various water insoluble alcohols, such as 1-butanol, 1-pentanol, 1-hexanol, benzyl alcohol and 2-butanol, were also acted as effective acceptors for the transxylosyl reaction, where a great part of the synthesized β-xylosides was found in the insoluble alcohol layer, only xylose and a trace of xylobiose being found in the water layer. Therefore, the synthesized β-xylosides, such as 1-hexyl β-xyloside, could be readily separated from the reaction mixture and crystallized after evaporation of the insoluble alcohol.
TL;DR: The effect of pH on the production of citric and gluconic acid, from beet molasses by Aspergillus niger, was studied using continuous culture to find the optimum specific activities.
Abstract: The effect of pH on the production of citric and gluconic acid, from beet molasses byAspergillus niger, was studied using continuous culture. At pH values above 2.5 gluconic acid was the major product, citric acid being the predominant product at low pH values. The optimum specific activities of citrate synthase, aconitase, NAD-linked isocitrate dehydrogenase, and NADP-linked isocitrate dehydrogenase occurred at pH 4 and of glucose oxidase at pH 5.
TL;DR: For all species tested, the minimal inhibitory and fungicidal concentrations for 90% of strains of both drugs were identical and the inoculum size did not have a major effect on the results.
Abstract: Terbinafine and amphotericin B MICs for 90% of strains tested were 1.6 and 0.4 micrograms/ml against Aspergillus fumigatus (16 strains), 0.8 and 3.2 micrograms/ml against Aspergillus flavus (10 strains), and 0.4 and 1.6 micrograms/ml against Aspergillus niger (10 strains), respectively. For all species tested, the minimal inhibitory and fungicidal concentrations for 90% of strains of both drugs were identical and the inoculum size did not have a major effect on the results.
TL;DR: The results demonstrate, that A. niger is capable of metabolizing lower chlorinated PCB mixtures (PCB 42 % chlorine), whereas no changes of the composition of PCB with higher chlorination levels ( PCB 54 % and 60 % chlorine) could be observed.
TL;DR: This chapter describes the purification of the β-D-glucosidase from a commercially available Aspergillus niger enzyme preparation and reports on some of its properties.
Abstract: Publisher Summary β-D-Glucosidases have been isolated and purified from a number of fungal culture filtrates. A number of β-glucosidases, including those from almond emulsin and from Aspergillus niger 15, do not have a strict requirement for a D-gluco configuration. The enzyme from almond emulsin catalyzes hydrolysis of both β-D-glucopyranosides and β-D-galactopyranosides and evidence has been obtained for the involvement of different enzyme active sites. An enzyme purified to homogeneity from culture filtrates of Aspergillus niger 15 has a very broad specificity with activity on β-D-glucosides, β-D-xylosides, β-D-galactosides, and β-L-arabinosides. β-glucosidase in combination with a specific endo-β-glucanase could find widespread application in the quantification of a range of β-D-glucans such as (1→4)-β-D-glucan, (1→3)-β-D-glucan, (1→3),(1→4)-β-D-glucan, and (1→3),1→6)-β-D-glucan. Together with endo-1,4-β-D-mannanase and β-D-mannosidase it may also prove useful in the measurement of β-D-glucomannans. A method for the assay of (1→3),(1→4)-β-D-glucan has already been developed using a highly purified β-D-glucosidase from a commercially available Aspergillus niger enzyme preparation. This chapter describes the purification of this enzyme and report on some of its properties.
TL;DR: Quantitative analysis of the binding carried out with 125I-labelled human fibrinogen on 33 species belonging to different groups clearly demonstrated that among all the fungi tested, only the pathogenic aspergilli significantly bound fibr inogen.
Abstract: The binding of human fibrinogen to the pathogenic aspergilli was investigated in vitro by different procedures using either fibrinogen in solution or fixed, insolubilized fibrinogen. Binding of fibrinogen was detected at the surface of hyphae and conidia by an immunofluorescence assay. Ultrastructural localization of the binding sites was visualized with fibrinogensensitized gold particles. The labelling was restricted to the outer cell wall layer of the ‘smooth’ walled conidia. Quantitative analysis of the binding carried out with 125I-labelled human fibrinogen on 33 species belonging to different groups (opportunistic fungi, strictly saprophytic or phytopathogenic fungi and dermatophytes or related species) clearly demonstrated that among all the fungi tested, only the pathogenic aspergilli significantly bound fibrinogen. The average amount of fibrinogen bound to individual conidia was also quantified. Binding was greater to Aspergillus niger (5-fold), Aspergillus fumigatus (2·5-fold) and Aspergillus fl...
TL;DR: The oliC3 gene of Aspergillus niger encodes an oligomycinresistant variant of the mitochondrial ATP synthase subunit 9 that can serve as a semi-dominant selectable marker for A. niger in transformation experiments.
Abstract: The oliC3 gene of Aspergillus niger has been isolated and sequenced. This gene encodes an oligomycinresistant variant of the mitochondrial ATP synthase subunit 9. In transformation experiments the gene can serve as a semi-dominant selectable marker for A. niger. It was possible to recognize transformants in which oliC3 had integrated at the homologous oliC locus, as opposed to elsewhere in the genome, by observation of phenotypes on medium containing oligomycin. DNA sequencing has allowed comparison of the deduced amino acid sequence with subunit 9 proteins from other species and comparison of 5′ untranslated sequences with those from other fungi.
TL;DR: It is of interest that a majority of peroxisomal proteins appear not to be glycosylated and that H 2 O 2 production in ligninolytic cultures of P. chrysosporium, presumed to be due to glucose oxidase activity, has been shown to be localized in periplasmic, perxisome-like structures.
Abstract: Publisher Summary Glucose oxidase catalyzes the oxidation of D-glucose to δ-D-gluconolactone and H 2 O 2 in the presence of molecular oxygen. In a subsequent step δ -D-gluconolactone is nonenzymatically hydrolyzed to D-gluconic acid. This enzyme has been demonstrated in various Aspergillus and Penicillium species and has recently been purified from Phanerochaete chrysosporium . This chapter focuses on assay method and purification procedure of the enzyme from Phanerochaete chrysosporium . It discusses the properties of the enzyme. Staining of the purified glucose oxidase from P. chrysosporium for protein-bound carbohydrate by the dansyl hydrazine method shows no detectable carbohydrate, whereas an equal amount of commercially prepared glucose oxidase from Aspergillus niger , which is known to be a glycoprotein, stains positive. This finding is of interest that a majority of peroxisomal proteins appear not to be glycosylated and that H 2 O 2 production in ligninolytic cultures of P. chrysosporium , presumed to be due to glucose oxidase activity, has been shown to be localized in periplasmic, peroxisome-like structures.
TL;DR: An endo-β-glucosidase was isolated from Aspergillus niger grown on a medium containing rutin as the sole carbon source, and was partially purified by affinity chromatography and found to be extracellular.
TL;DR: Diploid strains were obtained following protoplast fusion between two citric acid producers of Aspergillus niger, one for the solid culture and the other for the shaking culture; the best diploid strain produced 1.2 times as muchcitric acid as the parental strain in solid culture.
Abstract: Diploid strains were obtained following protoplast fusion between two citric acid producers of Aspergillus niger, one for the solid culture and the other for the shaking culture. In the shaking culture, all the diploid strains exhibited lower productivities than one parental strain. However, in the solid culture, some diploid strains exhibited higher productivities than either parental strain; the best diploid strain produced 1.2 times as much citric acid as the parental strain in solid culture.
TL;DR: Aspergillus niger was shown to carry out the regiospecific hydroxylation of acyclic monoterpene alcohols.
TL;DR: Methyl 3-methyl-8-hydroxy-4-decenoate, a new C10 fatty acid methyl ester, was isolated and characterized from Aspergillus niger var.
TL;DR: The objective of this review is to present a comparative study of the research on cellulase and hemicellulase enzymes from S. rolfsii.
Abstract: Microbial degradation of native cellulose to glucose is catalysed by cellulases which refers to a group of enzymes acting in concert. The extracellular enzyme systems of Trichoderma reesei, Sporotrichum pulverulentum, Aspergillus niger and Sclerotium rolfsii have been examined more extensively than other microbial sources. The objective of this review is to present a comparative study of the research on cellulase and hemicellulase enzymes from S. rolfsii.
TL;DR: Both shaken flask cultures and aerated fermenter cultures of the previously selected Aspergillus niger G-13 mutant were optimized for glucose oxidase production (β-d-glucose: oxygen 1-oxidoreductase, EC 1.1.3.4).
TL;DR: Segregation of diploid strains by a haploidizing agent was used to improve citric acid producing strains of Aspergillus niger, and all prototrophic segregants derived from one diploids strain had higher productivities in solid cultures without methanol than in those with methnol.
TL;DR: The results obtained show that Junlon-110 and Hostacerin bind to fungal walls, and it is possible that spore and hyphal aggregation is reduced by these compounds because of repulsion between particles resulting from ionized carboxyl groups on the polymer.
Abstract: SUMMARY: The electrophoretic behaviour of freshly harvested spores of Aspergillus niger, Phanerochaete chrysosporium and Geotrichum candidum was determined in solution at various pH values. Freshly harvested spores of all three species lacked positive mobility at low pH values, suggesting a preponderance of acidic surface groups. Spores of the ‘non-aggregating’ fungus, G. candidum, had a pH-mobility curve (peak of negative mobility between pH 3 and 4) which was quite different to those of spores of the ‘aggregating’ fungi, A. niger and P. chrysosporium. The pH-mobility curve of swollen spores of A. niger which had been incubated in medium differed from that of freshly harvested spores, suggesting that changes in the wall that occur during germination alter the electrophoretic properties of the spores; swollen spores of A. niger, unlike freshly harvested spores, had a negative mobility maximum at pH 5.0.
After treatment with Junlon-110 (a polyacrylic acid), spores of all three species had similar pH-mobility curves and all had peaks of negative mobility at pH 4.0. The electrophoretic mobility of spores of P. chrysosporium at pH 6.5 increased linearly with the concentration (0.01-0.4%, w/v) of Junlon used in the pre-treatment; electrophoretic mobility after pre-treatment with 0.005-0.1% (w/v) Hostacerin (sodium polyacrylate) increased only up to 0.01% (w/v) Hostacerin. The results obtained show that Junlon-110 and Hostacerin bind to fungal walls, and it is possible that spore and hyphal aggregation is reduced by these compounds because of repulsion between particles resulting from ionized carboxyl groups on the polymer.
TL;DR: This chapter describes the colorimetoric assay method using p -nitrophenyl-α-L-arabinofuranosidase from Aspergillus niger and discusses the physicochemical properties, stability, and substrate specificity of the enzyme.
Abstract: Publisher Summary α-L-Arabinofuranosidase catalyzes the hydrolysis of nonreducing terminal α-L-arabinofuranosidic linkages in L-arabinan, arabinoxylan, and other Larabinose-containing polysaccharides. In Aspergillus niger , this enzyme is produced inducibly in a medium containing L-arabinose or Larabinan. Phenyl- or p -nitrophenyl-α-L-arabinofuranoside is hydrolyzed by this enzyme action, thus, the amount of reducing group or nittrophenolate ion liberated is a measure of the enzyme activity. This chapter describes the colorimetoric assay method using p -nitrophenyl-α-L-arabinofuranoside. The chapter discusses the preparation and purification procedure of α-L-arabinofuranosidase from Aspergillus niger. The chapter concludes with a discussion on the physicochemical properties, stability, and substrate specificity of the enzyme. The enzyme is highly specific for nonreducing terminal α-L-arabinofuranosidic linkages and will not attack internal a-L-arabinofuranosyl linkages.