共查询到20条相似文献,搜索用时 15 毫秒
1.
K. Parvathi R. Naresh Kumar R. Nagendran 《World journal of microbiology & biotechnology》2007,23(5):671-676
Summary Biosorption of manganese from its aqueous solution using yeast biomass Saccharomyces cerevisiae and fungal biomass Aspergillus niger was carried out. Manganese biosorption equilibration time for A. niger and S. cerevisiae were found to be 60 and 20 min, with uptakes of 19.34 and 18.95 mg/g, respectively. Biosorption increased with rise in pH,
biomass, and manganese concentration. The biosorption equilibrium data fitted with the Freundlich isotherm model revealed
that A. niger was a better biosorbent of manganese than S. cerevisiae. 相似文献
2.
Y. P. Vinetsky A. M. Rozhkova A. M. Chulkin A. D. Satrutdinov O. A. Sinitsyna E. A. Fedorova A. O. Bekkarevich O. N. Okunev A. P. Sinitsyn 《Biochemistry. Biokhimii?a》2009,74(8):882-887
The gene encoding the xlnR xylanolytic activator of the heterologous fungus Aspergillus niger was incorporated into the Penicillium canescens genome. Integration of the xlnR gene resulted in the increase in a number of activities, i.e. endoxylanase, β-xylosidase, α-L-arabinofuranosidase, α-galactosidase, and feruloyl esterase, compared to the host P. canescens PCA 10 strain, while β-galactosidase, β-glucosidase, endoglucanase, and CMCase activities remained constant. Two different expression constructs were developed. The first consisted of the nucleotide sequence containing the mature P. canescens phytase gene under control of the axhA promoter region gene encoding A. niger (1,4)-β-D-arabinoxylan-arabinofuranohydrolase. The second construct combined the P. canescens phytase gene and the bgaS promoter region encoding homologous β-galactosidase. Both expression cassettes were transformed into P. canescens host strain containing xlnR. Phytase synthesis was observed only for strains with the bgaS promoter on arabinose-containing culture media. In conclusion, the bgaS and axhA promoters were regulated by different inducers and activators in the P. canescens strain containing a structural tandem of the axhA promoter and the gene of the xlnR xylanolytic activator. 相似文献
3.
Gene silencing using siRNA has been examined in the industrially-important fungus, Aspergillus niger. Protoplasts of an A. niger strain containing a single genomic copy of the Escherichia coli uidA gene, encoding β-glucuronidase (GUS), under control of the A. niger glaA promoter at the same genomic locus, were exposed to siRNA targeted against the uidA gene. Down-regulation of uidA mRNA
and GUS activity by siRNA was observed in mycelia that developed from the protoplasts. The down-regulation was transient and
was not carried over to conidiation. We concluded that gene silencing by siRNA provides a relatively quick method for analysis
of gene function in A. niger. 相似文献
4.
The aim of this work was to prepare recombinant amine oxidase from Aspergillus niger after overexpressing in yeast. The yeast expression vector pDR197 that includes a constitutive PMA1 promoter was used for
the expression in Saccharomyces cerevisiae. Recombinant amine oxidase was extracted from the growth medium of the yeast, purified to homogeneity and identified by activity
assay and MALDI-TOF peptide mass fingerprinting. Similarity search in the newly published A. niger genome identified six genes coding for copper amine oxidase, two of them corresponding to the previously described enzymes
AO-I a methylamine oxidase and three other genes coding for FAD amine oxidases. Thus, A. niger possesses an enormous metabolic gear to grow on amine compounds and thus support its saprophytic lifestyle. 相似文献
5.
Vania Castriani Fernandes da Silva Fabiano Jares Contesini Patrícia de Oliveira Carvalho 《Journal of industrial microbiology & biotechnology》2009,36(7):949-954
Considering the extraordinary microbial diversity and importance of fungi as enzyme producers, the search for new biocatalysts
with special characteristics and possible applications in biocatalysis is of great interest. Here, we report the performance
in the resolution of racemic ibuprofen of a native enantioselective lipase from Aspergillus niger, free and immobilized in five types of support (Accurel EP-100, Amberlite MB-1, Celite, Montmorillonite K10 and Silica gel).
Amberlite MB-1 was found to be the best support, with a conversion of 38.2%, enantiomeric excess of 50.7% and enantiomeric
ratio (E value) of 19 in 72 h of reaction. After a thorough optimization of several parameters, the E value of the immobilized Aspergillus niger lipase was increased (E = 23) in a shorter reaction period (48 h) at 35°C. Moreover, the immobilized Aspergillus niger lipase maintained an esterification activity of at least 80% after 8 months of storage at 4°C and could be reused at least
six times. 相似文献
6.
Two new effective microbial producers of inulinases were isolated from Jerusalem artichoke tubers grown in Thailand and identified
as Aspergillus niger TISTR 3570 and Candida
guilliermondii TISTR 5844. The inulinases produced by both these microorganisms were appropriate for hydrolysing inulin to fructose as the
principal product. An initial inulin concentration of ∼100 g l−1 and the enzyme concentration of 0.2 U g−1 of substrate, yielded 37.5 g l−1 of fructose in 20 h at 40°C when A. niger TISTR 3570 inulinase was the biocatalyst. The yield of fructose on inulin was 0.39 g g−1. Under identical conditions, the yeast inulinase afforded 35.3 g l−1 of fructose in 25 h. The fructose yield was 0.35 g g−1 of substrate. The fructose productivities were 1.9 g l−1 h−1 and 1.4 g l−1 h−1 for the mold and yeast enzymes, respectively. After 20 h of reaction, the mold enzyme hydrolysate contained 53% fructose
and more than 41% of initial inulin had been hydrolysed. Using the yeast enzymes, the hydrolysate contained nearly 38% fructose
at 25 h and nearly 36% of initial inulin had been hydrolysed. The A. niger TISTR 3570 inulinases exhibited both endo-inulinase and exo-inulinase activities. In contrast, the yeast inulinases displayed
mainly exo-inulinase activity. The mold and yeast crude inulinases mixed in the activity ratio of 5:1 proved superior to individual
crude inulinases in hydrolysing inulin to fructose. The enzyme mixture provided a better combination of endo- and exo-inulinase
activities than did the crude extracts of either the mold or the yeast individually. 相似文献
7.
Abed KF 《Journal of industrial microbiology & biotechnology》2008,35(9):1027-1032
The randomly amplified polymorphic DNA (RAPD) patterns of whole-cell lysates from five Aspergillus niger isolates, including one reference strain, two isolated from deep freeze, and two environmental strains from soil and plant infections, were investigated. PCR-RAPD analysis of genomic DNA was performed using eight primers (Tube-A1, Tube-A6, Tube-A17, Tube-B8, Tube-B11, Tube-B15, Tube-C5, Tube-C6). The RAPD assay discriminated between all strains. Comparison of deep freeze isolates showed identical RAPD patterns in some of the reference and environmental isolates. The data indicates that the RAPD technique is useful for fingerprinting A. niger. 相似文献
8.
Ochratoxin A is a mycotoxin produced by several Aspergillus and some Penicillium species which may be present in food and feed products. It can be enzymatically hydrolyzed into ochratoxin α and l-β-phenylalanine, thereby decreasing its toxicity. The ochratoxin A degradation capacity of Aspergillus niger is well known and here we report the isolation and purification of a novel enzyme from A. niger that hydrolyzes this mycotoxin. A wheat germ medium supplemented with ochratoxin A was used to produce the enzyme, which
was purified from culture filtrate by acetone precipitation and anion exchange chromatography. An overall purification of
2.5-fold with a recovery of 68% and a final specific activity of 36 U/mg was obtained. The enzyme is a metalloenzyme as it
was inhibited at 10 mM EDTA, whereas PMSF had no effect. The ochratoxin A hydrolytic enzyme presented a V
max of 0.44 μM/min and a K
m of 0.5 mM when the reaction was carried out at pH 7.5 and 37°C. 相似文献
9.
10.
Transposons are usually present in multiple copies in their hosts' genomes. Recombination between two transposon copies can result in chromosomal rearrangements. Here, we describe a recombination event between two copies of the retrotransposon ANiTa1 within the genome of the fungus Aspergillus niger (strain CBS513.88). The observed chromosomal rearrangement appears to be strain-specific, as the corresponding genomic region in another strain, ATCC1015, shows a different organization. Strain ATCC1015 actually seems to lack full-length ANiTa1 copies and possesses only solo LTR sequences. Presumably strain ATCC1015 was once colonized by ANiTa1, but then the genome subsequently lost the ANiTa1 copies. The striking genomic differences in ANiTa1 copy distribution leading to differences in the chromosomal structure between the two strains, ATTC1015 and CBS513.88, suggest that the activity of transposons may profoundly affect the evolution of different fungal strains. 相似文献
11.
For citric acid-accumulating Aspergillus niger cells, the enhancement of anaplerotic reactions replenishing tricarboxylic acid cycle intermediates predisposes the cells
to form the product. However, there is no increased citrate level in germinating spores and a complex sequence of developmental
events is needed to change the metabolism in a way that leads to an increased level of tricarboxylic acid cycle intermediates
in mycelia. A review of physiological events that cause such intracellular conditions, with the special emphasis on the discussion
of hexose transport into the cells and regulation of primary metabolism, predominantly of glycolytic flux during the process,
is presented. 相似文献
12.
A constitutive level of a mycelium-bound lipolytic activity from Aspergillus niger MYA 135 was strongly increased by 97% in medium supplemented with 2% olive oil. The constitutive lipase showed an optimal
activity in the pH range of 3.0–6.5, while the mycelium-bound lipase activity produced in the presence of olive oil had two
pH optima at pH 4 and 7. Interestingly, both lipolytic sources were cold-active showing high catalytic activities in the temperature
range of 4–8°C. These mycelium-bound lipase activities were also very stable in reaction mixtures containing methanol and
ethanol. In fact, the constitutive lipase maintained almost 100% of its activity after exposure by 1 h at 37°C in ethanol.
A simple methodology to evaluate suitable transesterification activities in organic solvents was also reported. 相似文献
13.
Xiao-Wei Yu Yong-Quan Li Shi-Miao Zhou Yu-Yi Zheng 《World journal of microbiology & biotechnology》2007,23(8):1091-1098
Aspergillus niger with mycelium-bound tannase activity was employed to investigate the synthesis of propyl gallate from gallic acid and 1-propanol
in organic solvents. The effects of various organic solvents (log P: −1.0 to 6.6) on the enzymatic reactions showed that benzene (log P: 2.0) was the most suitable solvent. The water content and protonation state of mycelium-bound enzyme both had significant
effects on the activity of tannase. The maximum molar conversion (65%) was achieved with 7.3% (v/v) 1-propanol and 5.56 mM
gallic acid at stirring speeds of 200 rev/min, 40 °C in presence of anhydrous sodium sulfate and PEG-10,000. Enzyme specificity
for the alcohol portion (C1–C8) of the ester showed that the optimum synthesis was observed with alcohols ranging from C3 to C5. 相似文献
14.
Certain cost-effective carbohydrate sources in crude as well as after purification were utilized as the sole sources of carbon for gluconic acid production using Aspergillus niger ORS-4.410 under submerged fermentation. Crude grape must (GM) and banana-must (BM) resulted into significant levels of gluconic acid production i.e. 62.6 and 54.6 g/l, respectively. The purification of grape and banana-must led to a 20–21% increase in gluconic acid yield. Molasses as such did not favour gluconate production (12.0 g/l) but a significant increase in production (60.3 g/l) was observed following hexacyanoferrate (HCF) treatment of the molasses. Rectified grape must (RGM) appeared to be best suitable substrate which after 144 h resulted in 73.2 g of gluconic acid/l with 80.6% yield followed by the yield obtained from the rectified banana must (RBM) (72.4%) and treated cane molasses (TM) (61.3%). Abundant growth of mould A. niger ORS-4.410 was observed with crude grape (0.131 g/l/h) and banana must (0.132 g/l/h). 相似文献
15.
The mycelia of Aspergillus niger, cultivated in a medium containing 45 g l−1 maltose, 66 g l−1 yeast extract, and 5 g l−1 K2HPO4 at 30°C and 200 rpm, were used as a biocatalyst in the glucosylation of ascorbic acid. Free mycelia from 3-day-old culture,
when used in a 6-h reaction with maltose as the acyl donor, gave 16.07 g l−1 ascorbic acid glucoside corresponding to a volumetric productivity of 2.68 g l−1 h−1 and a conversion of 67%. Mycelia from 3-day-old cultures were entrapped in calcium alginate beads and used as a catalyst
in the glucosylation of ascorbic acid. An ascorbic acid-to-maltose molar ratio of 1:9 was found to be optimum, and the conversion
reached 75% after 12 h. The concentration of ascorbic acid glucoside produced at this molar ratio was 17.95 g l−1, and the productivity was 1.5 g l−1 h−1. The biocatalyst was repeatedly used in a fixed bed bioreactor for the synthesis of ascorbic acid glucoside and approximately
17 g l−1 of ascorbic acid glucoside corresponding to a volumetric productivity of 1.42 g l−1 h−1 was produced in each use. The conversion was retained at 70% in each use. The entrapped mycelia also exhibited exceptionally
high reusability and storage stability. The product was purified to 85% by anion exchange and gel permeation chromatography
with a final yield of 75%. 相似文献
16.
Aspergillus strains are being considered as potential hosts for recombinant heterologous protein production because of their excellent
extracellular enzyme production characteristics. However, Aspergillus proteases are problematic in that they modify and degrade the heterologous proteins in the extracellular medium. In previous
studies we observed that media adjustments and maintenance of a filamentous morphology greatly reduced protease activity and
that a low concentration of the aspartic protease inhibitor pepstatin inhibited the latter protease activity to the extent
of approximately 90%. In this paper we report that when the serine protease inhibitor chymostatin is used in combination with
pepstatin 99–100% of total protease activity in Aspergillus cultures is inhibited. In protease assays a concentration of 30 μM chymostatin combined with 0.075 μM pepstatin was required
for maximum inhibition. Inhibitor concentrations of chymostatin and pepstatin of 120 and 0.3 μM, respectively, when added
to Aspergillus cultures, has no significant effect on biomass production, glucose utilization or culture pH pattern. The potential of using
these protease inhibitors in cultures of recombinant Aspergillus strains producing heterologous proteins will now be investigated to determine if the previously observed recombinant protein
denaturing effects of Aspergillus proteases can be negated. 相似文献
17.
Fungi metabolize polycyclic aromatic hydrocarbons by a number of detoxification processes, including the formation of sulfated
and glycosidated conjugates. A class of aromatic compounds in grapefruit is the furanocoumarins (FCs), and their metabolism
in humans is centrally involved in the “grapefruit/drug interactions.” Thus far, the metabolism by fungi of the major FCs
in grapefruit, including 6′, 7′-epoxybergamottin (EB), 6′, 7′-dihydroxybergamottin (DHB), and bergamottin (BM), has received
little attention. In this study, Aspergillus niger was observed to convert EB into DHB and a novel water-soluble metabolite (WSM). Bergaptol (BT) and BM were also metabolized
by A. niger to the WSM, which was identified as BT-5-sulfate using mass spectrometry, UV spectroscopy, chemical hydrolysis, and 1H and 13C nuclear magnetic resonance spectroscopy. Similarly, the fungus had a capability of metabolizing xanthotoxol (XT), a structural
isomer of BT, to a sulfated analog of BT-5-sulfate, presumably XT-8-sulfate. A possible enzyme-catalyzed pathway for the grapefruit
FC metabolism involving the cleavage of the geranyl group and the addition of a sulfate group is proposed. 相似文献
18.
The continuous production of citric acid from dairy wastewater was investigated using calcium-alginate immobilizedAspergillus niger ATCC 9142. The citric acid productivity and yield were strongly affected by the culture conditions. The optimal pH, temperature,
and dilution rate were 3.0, 30°C, and 0.025 h−1, respectively. Under optimal culture conditions, the maximum productivity, concentration, and yield of citric acid produced
by the calcium-alginate immobilizedAspergillus niger were 160 mg L−1 h−1, 4.5 g/L, and 70.3% respectively. The culture was continuously perfored for 20 days without any apparent loss in citric acid
productivity. Conversely, under the same conditions with a batch shake-flask culture, the maximum productivity, citric acid
concentration, and yield were only 63.3 mg L−1 h−1, 4.7 g/L and 51.4%, respectively. Therefore, the results suggest that the bioreactor used in this study could be potentially
used for continuous citric acid production from dairy wastewater by applying calcium-alginate immobilizedAspergillus niger. 相似文献
19.
Gheshlaghi R Scharer JM Moo-Young M Douglas PL 《Bioprocess and biosystems engineering》2007,30(6):397-418
A comprehensive metabolic network comprising three intracellular compartments (cytoplasm, mitochondrion and peroxisome) was
developed for Aspergillus niger. The metabolic flux network includes carbohydrate and amino acid metabolism in both anabolic and catabolic reactions. Linear
programming was used for the optimization of the specific growth rates in combination with 37 measured input and output fluxes
of the key metabolites to evaluate corresponding intracellular flux distributions throughout the batch fermentations. Logarithmic
sensitivity analysis revealed that the addition of proline, alanine and glutamate benefited growth in defined media. The experimental
observations and flux analysis showed that tyrosine was a potential candidate for biomass production improvement. Model predictions
was verified by conducting batch and fed-batch fermentations and it was found that the addition of the four amino acids according
to the predetermined schedule resulted in a 44 and 41% improvements in biomass and recombinant protein productions, respectively. 相似文献
20.
Susan Meijer Willem Adriaan de Jongh Lisbeth Olsson Jens Nielsen 《Applied microbiology and biotechnology》2009,84(1):157-167
The acuB gene of Aspergillus niger is an ortholog of facB in Aspergillus nidulans. Under carbon-repression conditions, facB is repressed, thereby preventing acetate metabolism when the repressing carbon source is present. Even though facB is reported to be repressed directly by CreA, it is believed that a basal level of FacB activity exists under glucose-repressive
conditions. In the present study, the effect of deletion of acuB on the physiology of A. niger was assessed. Differences in organic acid and acetate production, enzyme activities and extracellular amino and non-amino
organic acid production were determined under glucose-repressing and -derepressing conditions. Furthermore, consumption of
alternative carbon sources (e.g. xylose, citrate, lactate and succinate) was investigated. It was shown that AcuB has pleiotropic
effects on the physiology of A. niger. The results indicate that metabolic pathways that are not directly involved in acetate metabolism are influenced by acuB deletion. Clear differences in organic acid consumption and production were detected between the ∆acuB and reference strain. However, the hypothesis that AcuB is responsible for basal AcuA activity necessary for activation of
acetate metabolic pathways, even during growth on glucose, could not be confirmed. The experiments demonstrated that also
when acuB was deleted, no acetate was formed. Therefore, AcuB cannot be the only activator of AcuA, and another control mechanism has
to be available for activating AcuA. 相似文献