Showing papers on "Aspergillus niger published in 1994"
TL;DR: In a survey of the occurrence of ochratoxin A (OA)-positive strains isolated from feedstuffs, two of the 19 isolates of Aspergillus niger var. niger that were studied produced OA in 2% yeast extract-15% sucrose broth and in corn cultures as mentioned in this paper.
Abstract: In a survey of the occurrence of ochratoxin A (OA)-positive strains isolated from feedstuffs, two of the 19 isolates of Aspergillus niger var. niger that were studied produced OA in 2% yeast extract-15% sucrose broth and in corn cultures. This is the first report of production of OA by this species.
375 citations
TL;DR: Streptomyces olivochromogenes FAE showed activity against methyl ferulate, methyl sinapinate and methyl p-coumarate, but at a level 420-fold less than the A. niger esterase, which shows the necessity for C-3 on the phenol ring to be methoxylated and the aliphatic region of the substrate to be unsaturated.
Abstract: An inducible ferulic acid esterase (FAE-III) has been isolated, purified and partially characterized from Aspergillus niger after growth on oat spelt xylan. The purification procedure utilized ammonium sulphate precipitation, hydrophobic interaction and anion-exchange chromatography. The purified enzyme appeared almost pure by SDS-PAGE, with an apparent M
r of 36000. A single band, corresponding to a pl of 3·3 was observed on isoelectric focusing. With methyl ferulate as substrate, the enzyme had a specific activity of 67 IU (mg protein)-1, pH and temperature optima of 5 and 55–60 °C, respectively, and a Km of 2·08 mM and a V
max of 175 μmol min-1 (mg protein)-1. The enzyme was also active upon methyl sinapinate, methyl-3,4-dimethoxy cinnamate and methyl p-coumarate, but not benzoic acid methyl esters or methyl caffeate. Similarly, Streptomyces olivochromogenes FAE showed activity against methyl ferulate, methyl sinapinate and methyl p-coumarate, but at a level 420-fold less (on methyl ferulate) than the A. niger esterase. No activity was detected against the benzoate methyl esters. For both enzymes, this shows the necessity for C-3 on the phenol ring to be methoxylated and the aliphatic region of the substrate to be unsaturated. The specific activity of FAE-III on destarched wheat bran was 31 U (mg protein)-1 in the presence of Trichoderma viride xylanase and 3 U (mg protein)-1 in the absence. Apparent pH dependent binding of A. niger FAE-III to microcrystalline cellulose was also demonstrated.
210 citations
TL;DR: Using the response surface methodology, a second order polynomial model was derived and used to predict the number of days to obtain visible mold growth under various combinations of chitosan concentrations and °Brix in candied kumquat.
195 citations
TL;DR: The results indicate the potential value of PCR to detect Aspergillus species in BAL samples and, therefore, to identify neutropenic patients at risk for invasive aspergillosis.
Abstract: A PCR assay was developed for the diagnosis of invasive aspergillosis in immunocompromised patients. For this purpose, the complete nucleotide sequences of the genes encoding the 18S rRNA of Aspergillus nidulans, Aspergillus terreus, Aspergillus niger, and Aspergillus flavus were elucidated and aligned to the sequences of Aspergillus fumigatus and other clinically relevant prokaryotic and eukaryotic microorganisms. Genus-specific sequences could be identified in the V7 to V9 region of 18S rRNA. By using hot-start PCR, Southern blot hybridization, and restriction enzyme analysis, Aspergillus-specific and -sensitive determination was achieved. Five of six immunosuppressed mice experimentally infected with A. fumigatus developed infection, and rRNA could be detected in each case, even in livers with the absence of positive cultures. Aspergillus species were detected by PCR in four neutropenic patients with proven aspergillosis, although Aspergillus species had been isolated from only one bronchoalveolar lavage (BAL) fluid sample. Aspergillus species were detected by PCR in two more patients suspected of having infection. Positive PCR signals were obtained from the BAL samples of 3 of 8 neutropenic patients who had developed pulmonary infiltrates, but none were obtained from the samples of 14 nonimmunosuppressed patients. These results indicate the potential value of PCR to detect Aspergillus species in BAL samples and, therefore, to identify neutropenic patients at risk for invasive aspergillosis.
193 citations
TL;DR: The hypothesis that different kinds of ferulic acid esterases exist with different specificities for the oligosaccharide chain of the feruloylated substrates is supported.
184 citations
TL;DR: The data reveal the potential of the solid-state fermentation process for the economic production of tannase in Aspergillus niger PKL 104 and showed good stability at higher temperature and pH values.
177 citations
TL;DR: It is shown that in sucrose medium, A. niger produced high amounts of gluconic and oxalic acids, whereas in lactose permeate medium only oxalal acid was produced.
Abstract: The complex-forming compound oxalic acid can effectively solubilise metals such as aluminium, iron, lithium, and manganese. In order to produce high amounts of oxalic acid for biohydrometallurgical processes, it was the aim of this work to optimise oxalic acid production by Aspergillus niger, a fungus well known for its ability to produce oxalic acid. A. niger excreted 427 mmol oxalic acid 1−1 if it was cultivated in a pH-controlled (pH 6.0) fed-batch run in a 2-1 stirred tank reactor. Sucrose and lactose permeate were suitable carbon sources for oxalic acid production. In sucrose medium, A. niger produced high amounts of gluconic and oxalic acids, whereas in lactose permeate medium only oxalic acid was produced. Cultivation in green syrup and molasses media lead to high yields of biomass, but low oxalic acid production (<20 mmol 1−1).
153 citations
TL;DR: The refined crystal structures of a proteolytic fragment of glucoamylase from Aspergillus awamori var.
150 citations
TL;DR: The in situ immobilised tannase can be used for removing tannins responsible for unwanted effects in food or cosmetology processing and is officially approved in numerous countries for enzyme production in the food industry.
123 citations
TL;DR: In this paper, five sources of nitrogen, six minerals, six enzyme inducers and one each of growth as well as product promotors were screened by Plackett-Burman design, consisting of a total of 20 experiments for the above 19 sources/categories of medium ingredients, for their effect on the production of Aspergillus niger MRSS 234 in solid state fermentation system.
Abstract: Five sources of nitrogen, six minerals, six enzyme inducers and one each of growth as well as product promotors were screened by Plackett-Burman design, consisting of a total of 20 experiments for the above 19 sources/categories of medium ingredients, for their effect on the production of alpha-galactosidase by Aspergillus niger MRSS 234 in solid state fermentation system. The enzyme production was recorded from 2 to 5 days of fermentation. Data on enzyme titres was analysed by compatible analysis to obtain regression coefficients and t-ratios. Among the nitrogen sources, urea contributed positively to enzyme production and its effect increased with the fermentation time, in contrast to negative effect of all the ammonium salts used. Corn steep liquor, citric acid and legume seed flours showed significantly positive effects on enzyme production, though lactose showed negative effect upto 3 days of fermentation and then turned positive but not significantly. Calcium chloride and ferrous sulphate showed considerable negative effect, in contrast to mixed effect by other mineral salts studied. Among the legume seed flours, guar and French bean flours showed larger positive effects. The studies allowed the selection of urea, corn steep liquor, guar flour, soy bean flour and citric acid as most promising sources/categories for further optimization studies based on the effects as well as their trend with fermentation time. The use of Plackett-Burman design for rapid screening of large number of nutrients, in a very small number of experiments, for reliable short-listing of a few of most effective sources/categories for further optimization, has been scarce in submerged fermentation and never attempted earlier in solid state fermentation system.
101 citations
TL;DR: In this article, the biochemical properties of a commercial glycosidase from Aspergillus niger (Cytolase PCL5, Genencor) were investigated.
TL;DR: The mtDNA variation was distributed unevenly in the populations studied as mentioned in this paper, and the mtDNAs of most of the isolates collected in Australia were of the A. tubingensis type, with an unexpectedly high degree of variation, while the rDNA of these isolates exhibited the same A. niger pattern as that of isolates from other locations.
Abstract: The mitochondrial DNAs (mtDNAs) and the ribosomal repeat unit (ribosomal DNA, rDNA) of black Aspergillus isolates collected in various parts of the world were examined. Wide-ranging mtDNA variation was observed in natural populations of the Aspergillus niger aggregate. Most isolates were classifiable as A. niger or Aspergillus tubingensis according to their rDNA and mtDNA patterns. The mtDNA variation was distributed unevenly in the populations studied. The mtDNAs of most of the isolates collected in Australia were of the A. tubingensis type, with an unexpectedly high degree of variation, while the rDNA of these isolates exhibited the same A. tubingensis pattern as that of isolates from other locations. Some other local populations displayed very little polymorphism in their mtDNA and rDNA. Hybridization experiments in which cloned A. niger and Aspergillus nidulans mtDNA fragments were used revealed that the two main mtDNA groups corresponding to A. niger and A. tubingensis are more distantly related than...
TL;DR: In this paper, the authors estimate that between 200 and 400 million lb of citric acid are produced annually in the USA by fermentation of molasses and other sugars using the microorganism Aspergillus niger.
Abstract: Between 200 and 400 million lb of citric acid are produced annually in the USA by fermentation of molasses and other sugars using the microorganism Aspergillus niger. A lesser quantity of itaconic acid is manufactured by a similar technology using Aspergillus terreus. The recovery of citric acid from its fermentation broth via calcium salt precipitation is a costly, highly complex, sophisticated operation. USDOE estimates the cost of dry citric acid produced from a new plant to be about $0.59/lb, whereas the estimated cost of wet citric acid (in its fermentation broth) from a new plant is about $0.19/lb and from an old plant is about $0.15/lb. Citric acid rapidly reacts in hot (250 C), compressed (34.5 MPa) liquid water to form itaconic and citraconic acids with a combined selectivity that exceeds 90%. At higher temperatures (360 C), in the absence and presence of NaOH, itaconic acid decarboxylates to form methacrylic acid. The yield of methacrylic acid depends on the temperature, pH, and buffer strength of the medium, reaching a maximum of about 70% (by mole) of the itaconic acid feed. Conditions which favor the production of methacrylic acid also lead to the formation of its hydration product: hydroxyisobutyric acid. Undermore » optimum conditions the combined yield of methacrylic acid and hydroxyisobutyric acid from itaconic acid exceeds 80%. Results are consistent with well-established dehydration and decarboxylation mechanisms.« less
TL;DR: A model of the carbohydrate metabolism and the anaplerotic synthesis of oxalacetate in Aspergillus niger, under conditions of citric and accumulation, is presented and the system representation in power law forms is developed, showing that the steady state is locally stable.
Abstract: A model of the carbohydrate metabolism and the anaplerotic synthesis of oxalacetate in Aspergillus niger, under conditions of citric acid accumulation, is presented. In this first article we set the stage for subsequent analysis within the framework of the biochemical system theory (BST): we formulate the model and develop the system representation in power law forms, showing that the steady state is locally stable. In the second article, the control structure of the system is described and a rationale for the optimization of the process is developed
TL;DR: Electrolytic and hemicellulolytic enzymes were produced on extracted sweet sorghum silage by mixed culture solid substrate fermentation with Trichoderma reesei LM-1 (a Peruvian mutant) and Aspergillus niger ATCC 10864.
Abstract: Cellulolytic and hemicellulolytic enzymes were produced on extracted sweet sorghum silage by mixed culture solid substrate fermentation with Trichoderma reesei LM-1 (a Peruvian mutant) and Aspergillus niger ATCC 10864. Optimal cellulose and xylanase levels of 4 IU/g dry weight (DW) and 180 IU/g DW, respectively, were achieved in 120 h-fermentation when T. reesei, inoculated at 0 h, was followed by the inoculation of A. niger at 48 h.
TL;DR: The production of about 1.5 g citric acid/10 g dry coffee husk at a conversion of 82% (based on sugar consumed) under standardized conditions demonstrates the commercial potential of using the husk in this way.
Abstract: Aspergillus niger CFTRI 30 produced 1.3 g citric acid/10 g dry coffee husk in 72 h solid-state fermentation when the substrate was moistened with 0.075 M NaOH solution. Production was increased by 17% by adding a mixture of iron, copper and zinc to the medium but enrichment of the moist solid medium with (NH4)2SO4, sucrose or any of four enzymes did not improve production. The production of about 1.5 g citric acid/10 g dry coffee husk at a conversion of 82% (based on sugar consumed) under standardized conditions demonstrates the commercial potential of using the husk in this way.
TL;DR: Starch as an additional carbon source stimulated lipase biosynthesis when used in small amounts and addition of NH4NO3 as a nitrogen source, KH2PO4 as a phosphate source as well as Mg ions to the medium with inital pH 5.0 gave the best yield.
Abstract: Lipase biosynthesis occured in medium without lipids, but for improved production an inducer was needed. The source and concentration of an inducer had no signifficant effect. Starch as an additional carbon source stimulated lipase biosynthesis when used in small amounts. Addition of NH4NO3 as a nitrogen source, KH2PO4 as a phosphate source as well as Mg ions to the medium with inital pH 5.0 gave the best yield.
TL;DR: The results suggest that A. niger metabolizes pyrene by cytochrome P-450 monooxygenase enzyme systems.
Abstract: The metabolism of pyrene, a polycyclic aromatic hydrocarbon consisting of four rings, by Aspergillus niger SK 9317 was investigated. The metabolites formed were isolated and identified as 1-hydroxypyrene, 1,6- and 1,8-pyrenequinone, 1,6- and 1,8-dihydroxypyrene, 1-pyrenyl sulphate and 1-hydroxy-8-pyrenyl sulphate. This is the first report of 1-hydroxy-8-pyrenyl as a metabolite in the microbial metabolism of pyrene. The results suggest that A. niger metabolizes pyrene by cytochrome P-450 monooxygenase enzyme systems.
Journal Article•
TL;DR: Aspergillus niger V 22 B 35, a wild strain, was found to produce 4 times more pectinase than the reference strain, and the screening involved three simple and rapid steps.
Abstract: Screening of 248 cultures, isolatcd from Mexico's coffee growing areas, was carried out to select potent culture for production of pectinase from coffee pulp by solid state fermentation. A pectolytic strain of Aspergillus mer CH 4 was used as reference to evaluate the potential of the wild strains. The screening involved three simple and rapid steps. The first step involved the qualitative evaluation of pectolytic activities of 248 fungal strains on a selective solid agar medium, while the second one consisted of the quanlification of the pectolytic activities of selected 13 isolates in a submerged fermentation medium, with pectin as the sole carbon source. The third step involved the assay of four selected fungal isolates for their capacity to produce pectinase from coffee pulp by solid state fermentation. Aspergillus niger V 22 B 35, a wild strain, was found to produce 4 times more pectinase than the reference strain. Kemords : Coffee pulp, Solid state fermentation, Wild fungi, Pectinase, Simple three-step screening technique, AspergiUus niger.
TL;DR: The Tyr48-->Trp and Glu400-->Gln glucoamylases share particular features in displaying unusually high activity below pH 4.0-which reflects lack of the wild-type catalytic base function- and unusually low binding affinity at subsite 2.0.
Abstract: Replacement of the catalytic base Glu400 by glutamine in glucoamylase from Aspergillus niger affects both substrates ground-state binding and transition-state stabilization. Compared to those of the wild-type enzyme, Km values for maltose and maltoheptaose are 12- and 3-fold higher for the Glu400-->Gln mutant, with kcat values 35- and 60-fold lower, respectively, for the same substrates. This unusually high residual activity for a glycosylase mutant at a putative catalytic group is tentatively explained by a reorganization of the hydrogen bond network, using the crystal structure of the related Aspergillus awamori var. X100 glucoamylase in complex with 1-deoxynojirimycin [Harris, E. M. S., Aleshin, A. E., Firsov, L. M., & Honzatko, R. B. (1993) Biochemistry 32, 1618-1626]. Supposedly Gln400 in the mutant hydrogen bonds to the invariant Tyr48, as does Glu400 in the wild-type enzyme. For Tyr48-->Trp A. niger glucoamylase kcat is reduced 80-100-fold, while Km is increased only 2-3-fold. Gln401 also hydrogen bonds to Glu400, but its mutation to glutamic acid has only a minor effect on activity. The Tyr48-->Trp and Glu400-->Gln glucoamylases share particular features in displaying unusually high activity below pH 4.0-which reflects lack of the wild-type catalytic base function- and unusually low binding affinity at subsite 2. Both mutants have lost 13-16 kJ mol-1 in transition-state stabilization energy.(ABSTRACT TRUNCATED AT 250 WORDS)
TL;DR: Steady state sensitivity analysis of a model of carbohydrate metabolism and anaplerotic synthesis of oxalacetate and the flux and metabolite concentration control structure shows that the hexokinase/substrate transport step is the main controlling step of the pathway.
Abstract: Steady state sensitivity analysis of a model of carbohydrate metabolism and anaplerotic synthesis of oxalacetate were, in Aspergillus niger under conditions of citric acid accumulation, carried out. The flux and metabolite concentration control structure of the system obtained shows that the hexokinase/substrate transport step is the main controlling step of the pathway. The quantitative contribution of the other enzyme catalyzed or transport steps are also discussed. These results allow the design of a proper strategy of biotechnological manipulation aimed at improvement of the process.
TL;DR: In this paper, the nucleotide sequence of the previously cloned gene encoding α-L-arabinofuranosidases (ABF) from A. niger was determined.
Abstract: Aspergillus niger secretes three glycosylated glycosyl hydrolases which are involved in degradation of the plant cell wall polysaccharide L-arabinan: α-L-arabinofuranosidases (ABF) A and B, and endo-1,5-α-L-arabinase (ABN) A. The nucleotide sequence of the previously cloned gene encoding ABF A (abfA) from A. niger was determined. The coding region contains seven introns. Mature ABF A comprises 603 amino acids with a molecular mass of 65.4 kDa as deduced from the nucleotide sequence. The secreted enzyme is N-glycosylated. The primary structures of the three A. niger arabinases characterized lack similarity. Regulation of arabinase expression upon induction by sugar beet pulp and by L-arabitol was studied as a function of time. This was done in wild-type A. niger as well as in transformants carrying multiple copies of either one of the ABF-encoding genes. Each arabinase gene responded differently upon a mycelial transfer to L-arabitol-containing medium. Extra copies of abfA or abfB led to a decreased expression level of ABN A, though the repression elicited by abfB is stronger and more persistent than that effected by abfA. Multiple copies of both abf genes influence expression of the other ABF similarly, but to a far less pronounced degree than they affect ABN A synthesis. Four putative promoter elements, shared by all three arabinase genes, could be involved in coordination of L-arabinan degradation by A. niger.
TL;DR: Different transgenic plants of Brassica napus, Brassica nigra, Datura innoxia and Vicia narbonensis expressing the hph gene under the control of the 35s promoter were co-cultivated with mycelial material of Aspergillus niger in microcosms under sterile conditions, obtaining significantly higher number of hygromycin B-resistant colonies of re-isolated fungi.
Abstract: Different transgenic plants of Brassica napus, Brassica nigra, Datura innoxia and Vicia narbonensis expressing the hph gene under the control of the 35s promoter were co-cultivated with mycelial material of Aspergillus niger in microcosms under sterile conditions. A significantly higher number of hygromycin B-resistant colonies of re-isolated fungi was obtained if compared with co-cultures with non-transgenic plants. The hph gene and other foreign sequences could be detected in some of the resistant strains only for a short time after selection, indicating a rapid loss of foreign DNA. A more stable transgenic strain was obtained after co-culture with transgenic plants of D. innoxia including a high number of hph copies in their genome. DNA with detected pUC sequences was prepared to transform E. coli DH5α. One of the recovered plasmids is shown to include pieces of the plant-transforming vector and a foreign sequence. The 35s-regulated expression of genes is studied in A. niger.
TL;DR: Growth of Aspergillus niger and glucoamylase production correlated well with the water activity of the substrate (wheat bran plus corn flour) in a solid-state fermentation.
Abstract: Growth of Aspergillus niger and glucoamylase production correlated well with the water activity of the substrate (wheat bran plus corn flour) in a solid-state fermentation. Both were maximal at an initial water activity of 0.936. Glycoamylase reached 550 units/g dry substrate after 96 h.
TL;DR: Two inulinases, P-IA and P-IB, were purified from the culture filtrate of A. niger 817 and exhibited the endo-type mode of action on inulin, and lacked activity toward sucrose, raffinose or levan.
TL;DR: The development of an improved gene cloning strategy by complementation of mutant alleles in Aspergillus niger by the use of a fungal autonomously replicating vector, pAB4-ARp1, based on the introduction of a previously described sequence involved in autonomous replication into a pyrG integrative vector.
TL;DR: An aspartic proteinase (PEP) from the culture supernatant of a clinical isolate of Aspergillus fumigatus was purified to virtual homogeneity at a yield of 24% using affinity chromatography on pepstatin agarose.
Abstract: An aspartic proteinase (PEP) from the culture supernatant of a clinical isolate of Aspergillus fumigatus was purified to virtual homogeneity at a yield of 24%. The procedure involved affinity chromatography on pepstatin agarose, the interaction requiring a chaotropic salt (sodium trifluoroacetate) for complete clution of the enzyme. Among 11 amino acids of the N-terminal region, nine were identical with the corresponding sequence of the aspartic proteinase aspergillopepsin A from Aspergillus niger var. awamori (previously called Aspergillus awamori). Thus PEP belongs to the aspergillopepsins, a family of closely related aspartic proteinases produced by aspergilli. Specific antibodies against PEP were detected by dot blot assay in sera of two patients with aspergillosis. In addition. PEP antigen was demonstrated by immunofluorescence in mycotic human lung, using specifically elicited antibodies from guinea-pigs. PEP had an estimated molecular mass of 38 kDa and the pI was determined at pH 4·2. PEP is there...
TL;DR: Ethylene glycol, sorbitol and glycerol were used as water activity depressors to study the effect of water activity on pectinase production by Aspergillus niger CH4 to suggest sugar transport limitation as a consequence of aw depression.
Abstract: Ethylene glycol, sorbitol and glycerol were used as water activity depressors to study the effect of water activity on pectinase production byAspergillus niger CH4. Ethylene glycol depressed aw without supporting growth nor strongly affecting pectinase production in petri dish cultures. This depressor was used to evaluate the influence of water activity on exo-pectinase production by SSF. It was found that although pectinase production decreased at low aw values, this activity was present at aw values as low as 0.90. The specific activity increased up to 4.5 fold by reducing aw from 0.98 to 0.90. The reducing groups accumulated extracellularly suggesting sugar transport limitation as a consequence of aw depression.
TL;DR: In this paper, a thermostable inulinase was identified in a strain of A. niger and the highest activity was observed at 50 °C (50 Lml−1) and 77% and 34% of this was retained at 60° and 65°C, respectively.
Abstract: A thermostable inulinase was identified in a strain of A. niger. The highest activity was observed at 50 °C (50 Lml−1) and 77% and 34% of this was retained at 60° and 65°C, respectively. pH stability, the effect of thermal stabilizers such as Propylene glycol (10%) and Sorbitol (10%) and effects of different cations were investigated. It was found that the activity was completely inhibited by Ag+ and Hg2+, while Na+ had an activator effect.
TL;DR: The reactivity towards xylitol, the product or substrate these enzymes have in common, confirms their role in the L-arabinose catabolic pathway.
Abstract: An NADPH-dependent L-xylulose reductase [xylitol:NADP 4-oxidoreductase; EC 1.1.1.10 (LXDH)] from Aspergillus niger was purified and characterized. It is an octamer with a monomeric molecular mass of 32 kDa, showing high specificity for L-xylulose, xylitol and NADP(H). The K
m values for L-xylulose and xylitol are relatively high (16.5 and 925 mM, respectively). An NAD+-dependent xylitol dehydrogenase [xylitol:NAD+ 2-oxidoreductase; EC 1.1.1.9 (DXDH)] was partially purified from the same fungus. It has a monomeric molecular mass of 40 kDa and shows a high specificity for D-xylulose, xylitol and NAD(H). The K
m values for D-xylulose and xylitol are relatively low (approximately 4 and 50 mM, respectively). The reactivity towards xylitol, the product or substrate these enzymes have in common, confirms their role in the L-arabinose catabolic pathway.