共查询到20条相似文献,搜索用时 31 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.
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
3.
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
4.
Susan Meijer Michael Lynge Nielsen Lisbeth Olsson Jens Nielsen 《Journal of industrial microbiology & biotechnology》2009,36(10):1275-1280
With the availability of the genome sequence of the filamentous fungus Aspergillus niger, the use of targeted genetic modifications has become feasible. This, together with the fact that A. niger is well established industrially, makes this fungus an attractive micro-organism for creating a cell factory platform for
production of chemicals. Using molecular biology techniques, this study focused on metabolic engineering of A. niger to manipulate its organic acid production in the direction of succinic acid. The gene target for complete gene deletion was
cytosolic ATP: citrate lyase (acl), which had previously been identified by using genome-scale stoichiometric metabolic model simulations. The acl gene was deleted using the bipartite gene-targeting method, and the mutant was characterized in batch cultivation. It was
found that the succinic acid yield was increased threefold by deleting the acl gene. Additionally, the total amount of organic acids produced in the deletion strain was significantly increased. Genome-scale
stoichiometric metabolic model predictions can be used for identifying gene targets. Deletion of the acl led to increased succinic acid production by A. niger. 相似文献
5.
Eibes GM Lú-Chau TA Ruiz-Dueñas FJ Feijoo G Martínez MJ Martínez AT Lema JM 《Bioprocess and biosystems engineering》2009,32(1):129-134
Production of recombinant versatile peroxidase in Aspergillus hosts was optimized through the modification of temperature during bioreactor cultivations. To further this purpose, the
cDNA encoding a versatile peroxidase of Pleurotus eryngii was expressed under control of the alcohol dehydrogenase (alcA) promoter of Aspergillus nidulans. A dependence of recombinant peroxidase production on cultivation temperature was found. Lowering the culture temperature
from 28 to 19 °C enhanced the level of active peroxidase 5.8-fold and reduced the effective proteolytic activity twofold.
Thus, a maximum peroxidase activity of 466 U L-1 was reached. The same optimization scheme was applied to a recombinant Aspergillus niger that bore the alcohol dehydrogenase regulator (alcR), enabling transformation with the peroxidase cDNA under the same alcA
promoter. However, with this strain, the peroxidase activity was not improved, while the effective proteolytic activity was
increased between 3- and 11-fold compared to that obtained with A. nidulans. 相似文献
6.
Kaur P Lingner A Singh B Böer E Polajeva J Steinborn G Bode R Gellissen G Satyanarayana T Kunze G 《Antonie van Leeuwenhoek》2007,91(1):45-55
The extracellular acid phosphatase-encoding Arxula adeninivorans APHO1 gene was isolated using degenerated specific oligonucleotide primers in a PCR screening approach. The gene harbours an ORF of 1449 bp encoding a protein of 483 amino acids with a calculated molecular mass of 52.4 kDa. The sequence includes an N-terminal secretion sequence of 17 amino acids. The deduced amino acid sequence exhibits 54% identity to phytases from Aspergillus awamori, Asp. niger and Asp. ficuum and a more distant relationship to phytases of the yeasts Candida albicans and Debaryomyces hansenii (36–39% identity). The sequence contains the phosphohistidine signature and the conserved active site sequence of acid phosphatases. APHO1 expression is induced under conditions of phosphate limitation. Enzyme isolates from wild and recombinant strains with the APHO1 gene expressed under control of the strong A. adeninivorans-derived TEF1 promoter were characterized. For both proteins, a molecular mass of approx. 350 kDa, corresponding to a hexameric structure, a pH optimum of pH 4.8 and a temperature optimum of 60°C were determined. The preferred substrates include p-nitrophenyl-phosphate, pyridoxal-5-phosphate, 3-indoxyl-phosphate, 1-naphthylphosphate, ADP, glucose-6-phosphate, sodium-pyrophosphate, and phytic acid. Thus the enzyme is a secretory acid phosphatase with phytase activity and not a phytase as suggested by strong homology to such enzymes. 相似文献
7.
To elucidate the physiological adaptation of Escherichia coli due to cra gene knockout, a total of 3,911 gene expressions were investigated by DNA microarray for continuous culture. About 50 genes
were differentially regulated for the cra mutant. TCA cycle and glyoxylate shunt were down-regulated, while pentose phosphate (PP) pathway and Entner Doudoroff (ED)
pathway were up-regulated in the cra mutant. The glucose uptake rate and the acetate production rate were increased with less acetate consumption for the cra mutant. To identify the genes controlled by Cra protein, the Cra recognition weight matrix from foot-printing data was developed
and used to scan the whole genome. Several new Cra-binding sites were found, and some of the result was consistent with the
DNA microarray data. The ED pathway was active in the cra mutant; we constructed cra.edd double genes knockout mutant to block this pathway, where the acetate overflowed due to the down-regulation of aceA,B and icd gene expressions. Then we further constructed cra.edd.iclR triple genes knockout mutant to direct the carbon flow through the glyoxylate pathway. The cra.edd.iclR mutant showed the least acetate production, resulting in the highest cell yield together with the activation of the glycolysis
pathway, but the glucose consumption rate could not be improved.
Dayanidhi Sarkar and Khandaker Al Zaid Siddiquee have contributed equally. 相似文献
8.
To understand the metabolic characteristics of Clostridium acetobutylicum and to examine the potential for enhanced butanol production, we reconstructed the genome-scale metabolic network from its
annotated genomic sequence and analyzed strategies to improve its butanol production. The generated reconstructed network
consists of 502 reactions and 479 metabolites and was used as the basis for an in silico model that could compute metabolic and growth performance for comparison with fermentation data. The in silico model successfully predicted metabolic fluxes during the acidogenic phase using classical flux balance analysis. Nonlinear
programming was used to predict metabolic fluxes during the solventogenic phase. In addition, essential genes were predicted
via single gene deletion studies. This genome-scale in silico metabolic model of C. acetobutylicum should be useful for genome-wide metabolic analysis as well as strain development for improving production of biochemicals,
including butanol.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
J. L. and H. Y. equally contributed to this work. 相似文献
9.
Wenjuan Yao Xiaozhao Deng Hui Zhong Miao Liu Pu Zheng Zhihao Sun Yun Zhang 《Journal of industrial microbiology & biotechnology》2009,36(7):911-921
Corynebacterium glutamicum strains are used for the fermentative production of l-glutamate. Five C. glutamicum deletion mutants were isolated by two rounds of selection for homologous recombination and identified by Southern blot analysis.
The growth, glucose consumption and glutamate production of the mutants were analyzed and compared with the wild-type ATCC
13032 strain. Double disruption of dtsR1 (encoding a subunit of acetyl-CoA carboxylase complex) and pyc (encoding pyruvate carboxylase) caused efficient overproduction of l-glutamate in C. glutamicum; production was much higher than that of the wild-type strain and ΔdtsR1 strain under glutamate-inducing conditions. In the absence of any inducing conditions, the amount of glutamate produced by
the double-deletion strain ΔdtsR1Δpyc was more than that of the mutant ΔdtsR1. The activity of phosphoenolpyruvate carboxylase (PEPC) was found to be higher in the ΔdtsR1Δpyc strain than in the ΔdtsR1 strain and the wild-type strain. Therefore, PEPC appears to be an important anaplerotic enzyme for glutamate synthesis in
ΔdtsR1 derivatives. Moreover, this conclusion was confirmed by overexpression of ppc and pyc in the two double-deletion strains (ΔdtsR1Δppc and ΔdtsR1Δpyc), respectively. Based on the data generated in this investigation, we suggest a new method that will improve glutamate production
strains and provide a better understanding of the interaction(s) between the anaplerotic pathway and fatty acid synthesis. 相似文献
10.
Biosorption is an eco-friendly and cost-effective method for treating the dye house effluents. Aspergillus niger and Trichoderma sp. were cultivated in bulk and biomasses used as biosorbents for the biosorption of an azo dye Orange G. Batch biosorption
studies were performed for the removal of Orange G from aqueous solutions by varying the parameters like initial aqueous phase
pH, biomass dosage, and initial dye concentration. It was found that the maximum biosorption was occurred at pH 2. Experimental
data were analyzed by model equations such as Langmuir and Freundlich isotherms, and it was found that both the isotherm models
best fitted the adsorption data. The monolayer saturation capacity was 0.48 mg/g for Aspergillus niger and 0.45 mg/g for Trichoderma sp. biomasses. The biosorption kinetic data were tested with pseudo first-order and pseudo second-order rate equations, and
it was found that the pseudo second-order model fitted the data well for both the biomasses. The rate constant for the pseudo
second-order model was found to be 10–0.8 (g/mg min−1) for Aspergillus niger and 8–0.4 (g/mg min−1) for Trichoderma sp. by varying the initial dye concentrations from 5 to 25 mg/l. It was found that the biomass obtained from Aspergillus niger was a better biosorbent for the biosorption of Orange G dye when compared to Trichoderma sp. 相似文献
11.
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
12.
J. H. A. Betini M. Michelin S. C. Peixoto-Nogueira J. A. Jorge H. F. Terenzi M. L. T. M. Polizeli 《Bioprocess and biosystems engineering》2009,32(6):819-824
This study describes the production of xylanases from Aspergillus niveus, A. niger, and A. ochraceus under solid-state fermentation using agro-industrial residues as substrates. Enzyme production was improved using a mixture
of wheat bran and yeast extract or peptone. When a mixture of corncob and wheat bran was used, xylanase production from A. niger and A. ochraceus increased by 18%. All cultures were incubated at 30 °C at 70–80% relative humidity for 96 h. For biobleaching assays, 10
or 35 U of xylanase/g dry cellulose pulp were incubated at pH 5.5 for 1 or 2 h, at 55 °C. The delignification efficiency was
20%, the brightness (percentage of ISO) increased two to three points and the viscosity was maintained confirming the absence
of cellulolytic activity. These results indicated that the use of xylanases could help to reduce the amount of chlorine compounds
used in cellulose pulp treatment. 相似文献
13.
Commercial lipase preparations and mycelium bound lipase from Aspergillus niger NCIM 1207 were used for esterification of acetic acid with isoamyl alcohol to obtain isoamyl acetate. The esterification
reaction was carried out at 30°C in n-hexane with shaking at 120 rpm. Initial reaction rates, conversion efficiency and isoamyl acetate concentration obtained
using Novozyme 435 were the highest. Mycelium bound lipase of A. niger NCIM 1207 produced maximal isoamyl acetate formation at an alcohol/acid ratio of 1.6. Acetic acid at higher concentrations
than required for the critical alcohol/acid ratio lower than 1.3 and higher than 1.6 resulted in decreased yields of isoamyl
acetate probably owing to lowering of micro-aqueous environmental pH around the enzyme leading to inhibition of enzyme activity.
Mycelium bound A. niger lipase produced 80 g/l of isoamyl acetate within 96 h even though extremely less amount of enzyme activity was used for esterification.
The presence of sodium sulphate during esterification reaction at higher substrate concentration resulted in increased conversion
efficiency when we used mycelium bound enzyme preparations of A. niger NCIM 1207. This could be due to removal of excess water released during esterification reaction by sodium sulphate. High
ester concentration (286.5 g/l) and conversion (73.5%) were obtained within 24 h using Novozyme 435 under these conditions. 相似文献
14.
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
15.
Bo Young Jeon Soo Jin Kim Dae Hee Kim Byung Kwan Na Doo Hyun Park Hung Thuan Tran Ruihong Zhang Dae Hee Ahn 《Biotechnology and Bioprocess Engineering》2007,12(5):566-573
Aspergillus niger hyphae were found to grow with unliquefied potato starch under aerobic conditions, but did not grow under anaerobic conditions.
The raw culture ofA. niger catalyzed saccharification of potato starch to glucose, producing approximately 12 g glucose/L/day/ The extracellular enzyme
activity was decreased in proportion to incubation time, and approximately 64% of initial activity was maintained after 3
days. At 50°C,A. niger hyphae growth stopped, while the extracellular enzyme activity peaked. On the basis of theA. niger growth property and enzyme activity, we designed a serial bioreactor system composed of four different reactors. Fungal hyphae
were cultivated in reactor I at 30°C, uniquefied starch was saccharified to glycose by a fungal hyphae culture in reactors
II and III at 50°C, and glucose was fermented to ethanol bySaccharomyces cerevisiae in reactor IV. The total glucose produced by fungal hyphae in reactor I and saccharification in reactor II was about 42 g/L/day.
Ethanol production in reactor IV was approximately 22 g/L/day, which corresponds to about 79% of the theoretical maximum produced
from 55 g starch/L/day. 相似文献
16.
The foodborne pathogen Bacillus cereus can form biofilms on various food contact surfaces, leading to contamination of food products. To study the mechanisms of
biofilm formation by B. cereus, a Tn5401 library was generated from strain UW101C. Eight thousand mutants were screened in EPS, a low nutrient medium. One mutant
(M124), with a disruption in codY, developed fourfold less biofilm than the wild-type, and its defective biofilm phenotype was rescued by complementation.
Addition of 0.1% casamino acids to EPS prolonged the duration of biofilms in the wild-type but not codY mutant. When decoyinine, a GTP synthesis inhibitor, was added to EPS, biofilm formation was decreased in the wild-type but
not the mutant. The codY mutant produced three times higher protease activity than the wild-type. Zymogram and SDS-PAGE data showed that production
of the protease (∼130 kDa) was repressed by CodY. Addition of proteinase K to EPS decreased biofilm formation by the wild-type.
Using a dpp-lacZ fusion reporter system, it was shown that that the B. cereus CodY can sense amino acids and GTP levels. These data suggest that by responding to amino acids and intracellular GTP levels
CodY represses production of an unknown protease and is involved in biofilm formation. 相似文献
17.
F. W. Wang Z. M. Hou C. R. Wang P. Li D. H. Shi 《World journal of microbiology & biotechnology》2008,24(10):2143-2147
The metabolites of endophytic fungus Penicillium sp. from the leaf of Hopea hainanensis were reported for the first time. By bioassay-guided fractionation, the EtOAc extract of a solid-matrix steady culture of
this fungus afforded six compounds, which were identified through a combination of spectral and chemical methods (IR, MS,
1H- and 13C-NMR) to be monomethylsulochrin (1), rhizoctonic acid (2), asperfumoid (3), physcion (4), 7,8-dimethyl-iso-alloxazine (5) and 3,5-dichloro-p-anisic acid (6). Compounds 2, 3 and 6 were obtained from Penicillium sp. for the first time. All of the six isolates were subjected to in vitro bioactive assays including antifungal action against
three human pathogenic fungi Candida albicans, Trichophyton rubrum and Aspergillus niger and cytotoxic activity against the human nasopharyngeal epidermoid tumor KB cell line and human liver cancer HepG2 cell line.
As a result, compounds 2–4 and 6 inhibited the growth of C. albicans with MICs of 40.0, 20.0, 50.0 and 15.0 μg/ml, respectively and the compound 6 showed growth inhibition against A. niger with MICs of 40.0 μg/ml. In addition, compounds 1–3 and 6 exhibited cytotoxic activity against KB cell line with IC50 value of 30.0, 20.0, 20.0, 5.0 μg/ml, respectively and against HepG2 cell line with IC50 value of 30.0, 25.0, 15.0, 10.0 μg/ml, respectively. 相似文献
18.
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
19.
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
20.
Combined gasification and fermentation technologies can potentially produce biofuels from renewable biomass. Gasification
generates synthesis gas consisting primarily of CO, CO2, H2, N2, with smaller amounts of CH4, NOx, O2, C2 compounds, ash and tars. Several anaerobic bacteria species can ferment bottled mixtures of pure synthesis gas constituents.
However, there are challenges to maintaining culture viability of synthesis gas exposed cells. This study was designed to
enhance culture stability and improve ethanol-to-acetate ratios using resting (non-growing) cells in synthesis gas fermentation.
Resting cell states were induced in autotrophic Clostridium ljungdahlii cultures with minimal ethanol and acetate production due to low metabolic activity compared to growing cell production levels
of 5.2 and 40.1 mM of ethanol and acetate. Clostridium autoethanogenum cultures were not induced into true resting states but did show improvement in total ethanol production (from 5.1 mM in growing
cultures to 9.4 in one nitrogen-limited medium) as well as increased shifts in ethanol-to-acetate production ratios. 相似文献