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1.
M. E. Acuña-Argüelles M. Gutiérrez-Rojas G. Viniegra-González E. Favela-Torres 《Applied microbiology and biotechnology》1995,43(5):808-814
Three extracellular pectinases were produced byAspergillus niger CH4 by submerged and solid-state fermentation, and their physicochemical and kinetic properties were studied. The highest
productivities of endo- and exo-pectinase and pectin lyase were obtained with solid-state fermentation. The kinetic and physicochemical
properties of these enzymes were influenced by the type of culture method used. All activities were very different in terms
of pH and temperature optima, stability at different pH and temperature values and affinity for the substrate (K
m values). In solid-state fermentation, all pectinase activities were more stable at extreme pH and temperature values but
theK
m values of endo-pectinase and pectin lyase were higher with respect to those activities obtained by the submerged-culture
technique. The pectin lyase activity obtained by the submerged-culture technique showed substrate inhibition but the enzyme
obtained by solid-state fermentation did not. Electrophoresis, using sodium dodecyl sulphate/polyacrylamide gel with enzymatic
extracts obtained for both culture methods, showed the same number on protein bands but some differences were found in their
electrophoretic position. The results obtained in this work suggest that the culture method (submerged or solid-state) may
be responsible for inducing changes in some of the pectinolytic enzymes produced byA. niger. 相似文献
2.
3.
S. Parvez M. I. Rajoka M. N. Ahmed F. Latif R. Shahid K. A. Malik 《Folia microbiologica》1998,43(1):59-62
Citric acid production from sugar cane molasses byAspergillus niger NIAB 280 was studied in a batch cultivation process. A maximum of 90 g/L total sugar was utilized in citric acid production
medium. From the parental strainA. niger, mutant strains showing resistance to 2-deoxyglucose in Vogal's medium containing molasses as a carbon source were induced
by γ-irradiation. Among the new series of mutant strains, strain RP7 produced 120 g/L while the parental strain produced 80
g/L citric acid (1.5-fold improvement) from 150 g/L of molasses sugars. The period of citric acid production was shortened
from 10 d for the wild-type strain to 6–7 d for the mutant strain. The efficiency of substrate uptake rate with respect to
total volume substrate consumption rate,Q
s (g per L per h) and specific substrate consumption rate,q
s (g substrate per g cells per h) revealed that the mutant grew faster than its parent. This indicated that the selected mutant
is insensitive to catabolite repression by higher concentrations of sugars for citric acid production. With respect to the
product yield coefficient (Y
p/x), volume productivity (Q
p) and specific product yields (q
p), the mutant strain is significantly (p≤0.05) improved over the parental strain. 相似文献
4.
Ya-Hong Xiong Jian-Zhong Liu Hai-Yuan Song Liang-Nian Ji 《World journal of microbiology & biotechnology》2004,20(9):935-939
SummarySelf-directing optimization was successfully employed to determine the optimal combination of engineering parameters, viz., pH, aeration rate and agitation rate, for extracellular ribonuclease production by Aspergillus niger SA-13-20 in a batch bioreactor. Maximal RNase production of 5.38 IU ml–1 was obtained at controlled pH of 2.33, aeration rate of 1.67 v/v/m and agitation rate of 850 rev/min. The effect of oxygen on the fermentation was also investigated. With increase in volumetric oxygen transfer coefficients (KLa), cell growth and RNase production first increased and then decreased. RNase production was further increased to 7.10 IU ml–1 and the fermentation time was shortened from 96 to 72 h by controlling dissolved oxygen concentration at 10% saturation by aerating oxygen after about 28 h of fermentation under the above optimal condition. The kinetic model showed that RNase production by A. niger SA-13-20 was growth-associated. 相似文献
5.
Detry J Rosenbaum T Lütz S Hahn D Jaeger KE Müller M Eggert T 《Applied microbiology and biotechnology》2006,72(6):1107-1116
Two extracellular lipases from Bacillus subtilis, B. subtilis lipase A and lipase B, have been expressed in the heterologous host Escherichia coli, biochemically characterized and used for the kinetic resolution of (rac)-trans-1,2-diacetoxycyclohexane. Both enzymes were selectively acting on the (R,R)-enantiomer of the racemic substrate, highly specifically hydrolyzing only one of the two ester groups present, thus allowing the preparation of enantiopure (R,R)- and (S,S)-cyclohexane-trans-1,2-diol. The reaction conditions for the use of purified enzyme and crude cell lyophilizate were optimized and reactions in batch and repetitive batch modes were carried out on a preparative scale to yield enantiopure product (>99% enantiomeric excess). 相似文献
6.
Summary Thirty-nine fungal cultures belonging to the genera of Aspergillus, Podospora, Sordaria, Cbaetomium, Iodophanus, Scleotinia, Coniella, Pellicularia and others, were examined for the production of enzymes which macerate the mandarin orange peel using a wheat bran as substrate. An isolated strain of Aspergillus niger was an excellent producer of macerating enzymes compared to other organisms tested. The peel of the mandarin orange could be macerated by the crude enzymes produced by isolated A. niger. The maceration of 1 g of peel/24 h yielded 0.57 g of reducing sugars. Expressed differently, 83% of solid peel materials were released from the peel into the water/24 h under the following conditions: a peel concentration of 8 g peel/l, a crude enzyme concentration of 1 g protein/l, a temperature of 40°C, a pH of 5, a 24 h incubation time and 120 rpm reciprocal shaking. The test of the macerating activity of commercially available hydrolases on the orange peel showed that the two samples of pectinase originating from A. niger had about the same activity as isolated A. niger whereas the two samples of cellulase originating from Trichoderma viride had remarkably lower activities than A. niger. 相似文献
7.
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
8.
Maria R. Castillo Marcel Gutierrez-Correa James C. Linden Robert P. Tengerdy 《Biotechnology letters》1994,16(9):967-972
Summary 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. 相似文献
9.
Synergistic effect of Aspergillus niger and Trichoderma reesei enzyme sets on the saccharification of wheat straw and sugarcane bagasse
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Joost van den Brink Gabriela Piccolo Maitan‐Alfenas Gen Zou Chengshu Wang Zhihua Zhou Valéria Monteze Guimarães Ronald P. de Vries 《Biotechnology journal》2014,9(10):1329-1338
Plant‐degrading enzymes can be produced by fungi on abundantly available low‐cost plant biomass. However, enzymes sets after growth on complex substrates need to be better understood, especially with emphasis on differences between fungal species and the influence of inhibitory compounds in plant substrates, such as monosaccharides. In this study, Aspergillus niger and Trichoderma reesei were evaluated for the production of enzyme sets after growth on two “second generation” substrates: wheat straw (WS) and sugarcane bagasse (SCB). A. niger and T. reesei produced different sets of (hemi‐)cellulolytic enzymes after growth on WS and SCB. This was reflected in an overall strong synergistic effect in releasing sugars during saccharification using A. niger and T. reesei enzyme sets. T. reesei produced less hydrolytic enzymes after growth on non‐washed SCB. The sensitivity to non‐washed plant substrates was not reduced by using CreA/Cre1 mutants of T. reesei and A. niger with a defective carbon catabolite repression. The importance of removing monosaccharides for producing enzymes was further underlined by the decrease in hydrolytic activities with increased glucose concentrations in WS media. This study showed the importance of removing monosaccharides from the enzyme production media and combining T. reesei and A. niger enzyme sets to improve plant biomass saccharification. 相似文献
10.
11.
12.
《Bioscience, biotechnology, and biochemistry》2013,77(9):1732-1736
Glucoamylases from Aspergillus niger and Rhizopus niveus catalyzed condensation of 2-deoxy-D-glucose (dGlc) to yield deoxy-glucooligosaccharides with polymerization degrees of 2–5. The enzymes also gave a small amount of products from 3-deoxy-o-glucose, but no products from 6-deoxy-D-glucose. A. niger α-glucosidase also catalyzed condensation of dGlc, while Torula and Saccharomyces α-glucosidases had low activity. α-l,4-, 1,6-, and 1,3-linked deoxy-glucobioses were isolated and identified as the products of A. niger glucoamylase and A. niger α-glucosidase. In the reaction of the glucoamylase, 1,4- and 1,3-linked saccharides decreased with an increase of 1,6-linked one. A. niger α-glucosidase produced α-1,6-linked disaccharide predominantly during the whole course of the reaction. 相似文献
13.
Batch assays are currently used to study the kinetic behavior of microbial growth. However, it has been shown that the outcome
of batch experiments is greatly influenced by the initial ratio of substrate concentration (S
o) to biomass concentration (X
o). Substrate-sufficient batch culture is known to have mechanisms of spilling energy that lead to significant nongrowth-associated
substrate consumption, and the Monod equation is no longer appropriate. By incorporating substrate consumption associated
with energy spilling into the balance of the substrate oxidation reaction, a kinetic model for the observed specific substrate
consumption rate was developed for substrate-sufficient batch culture of activated sludge, and was further verified by experimental
data. It was demonstrated that the specific substrate consumption rate increased with the increase of the S
o/X
o ratio, and the majority of substrate was consumed through energy spilling at high S
o/X
o ratios. It appears that the S
o/X
o ratio is a key parameter in regulating metabolic pathways of microorganisms.
Received: 18 January 1999 / Received revision: 7 May 1999 / Accepted: 28 May 1999 相似文献
14.
The kinetic properties of α-galactosidase of Mortierella vinacea were investigated in detail using PNPG (p-nitrophenyl-α-D -galactopyranoside) as a substrate. Consequently, the enzyme was markedly inhibited not only by the substrate, but also by the galactose hydrolized. The initial rate of reaction at sufficiently high substrate concentrations, however, did not fall to zero and did approach a finite value. Galactose behaved as a mixed inhibitor and was neither totally competitive nor totally noncompetitive. A rate equation was obtained from a generalized equation derived from a kinetic model which took both the inhibitions into consideration. The constants used in the equation were appropriately estimated. The calculated rate agreed fairly well with the observed initial rate. Moreover, the PNPG hydrolysis progressing in a batch system was found to be approximately representable by simple first order kinetics in which the rate constant was dependent on the initial substrate concentration. 相似文献
15.
On the safety of Aspergillus niger--a review 总被引:6,自引:0,他引:6
Schuster E Dunn-Coleman N Frisvad JC Van Dijck PW 《Applied microbiology and biotechnology》2002,59(4-5):426-435
Aspergillus niger is one of the most important microorganisms used in biotechnology. It has been in use already for many decades to produce
extracellular (food) enzymes and citric acid. In fact, citric acid and many A. niger enzymes are considered GRAS by the United States Food and Drug Administration. In addition, A. niger is used for biotransformations and waste treatment. In the last two decades, A. niger has been developed as an important transformation host to over-express food enzymes. Being pre-dated by older names, the
name A. niger has been conserved for economical and information retrieval reasons and there is a taxonomical consensus based on molecular
data that the only other common species closely related to A. niger in the Aspergillus series Nigri is A. tubingensis. A. niger, like other filamentous fungi, should be treated carefully to avoid the formation of spore dust. However, compared with other
filamentous fungi, it does not stand out as a particular problem concerning allergy or mycopathology. A few medical cases,
e.g. lung infections, have been reported, but always in severely immunocompromised patients. In tropical areas, ear infections
(otomycosis) do occur due to A. niger invasion of the outer ear canal but this may be caused by mechanical damage of the skin barrier. A. niger strains produce a series of secondary metabolites, but it is only ochratoxin A that can be regarded as a mycotoxin in the
strict sense of the word. Only 3–10% of the strains examined for ochratoxin A production have tested positive under favourable
conditions. New and unknown isolates should be checked for ochratoxin A production before they are developed as production
organisms. It is concluded, with these restrictions, that A. niger is a safe production organism.
Electronic Publication 相似文献
16.
Seinosuke Ueda Celia T. Zenin Domingos A. Monteiro Yong K. Park 《Biotechnology and bioengineering》1981,23(2):291-299
Raw cassava root starch was transformed into ethanol in a one-step process of fermentation, in which are combined the conventional processes of liquefaction, saccharification, and fermentation to alcohol. Aspergillus awamori NRRL 3112 and Aspergillus niger were cultivated on wheat bran and used as Koji enzymes. Commercial A. niger amyloglucosidase was also used in this experiment. A raw cassava root homogenate–enzymes–yeast mixture fermented optimally at pH 3.5 and 30°C, for five days and produced ethanol. Alcohol yields from raw cassava roots were between 82.3 and 99.6%. Fungal Koji enzymes effectively decreased the viscosity of cassava root fermentation mashes during incubation. Commercial A. niger amyloglucosidase decreased the viscosity slightly. Reduction of viscosity of fermentation mashes was 40, 84, and 93% by commercial amyloglucosidase, A. awamori, and A. niger enzymes, respectively. The reduction of viscosity of fermentation mashes is probably due to the hydrolysis of pentosans by Koji enzymes. 相似文献
17.
Beauvericin (BEA) is a cyclic hexadepsipeptide mycotoxin with notable phytotoxic and insecticidal activities. Fusarium redolens Dzf2 is a highly BEA-producing fungus isolated from a medicinal plant. The aim of the current study was to develop a simple
and valid kinetic model for F. redolens Dzf2 mycelial growth and the optimal fed-batch operation for efficient BEA production. A modified Monod model with substrate
(glucose) and product (BEA) inhibition was constructed based on the culture characteristics of F. redolens Dzf2 mycelia in a liquid medium. Model parameters were derived by simulation of the experimental data from batch culture.
The model fitted closely with the experimental data over 20–50 g l−1 glucose concentration range in batch fermentation. The kinetic model together with the stoichiometric relationships for biomass,
substrate and product was applied to predict the optimal feeding scheme for fed-batch fermentation, leading to 54% higher
BEA yield (299 mg l−1) than in the batch culture (194 mg l−1). The modified Monod model incorporating substrate and product inhibition was proven adequate for describing the growth kinetics
of F. redolens Dzf2 mycelial culture at suitable but not excessive initial glucose levels in batch and fed-batch cultures. 相似文献
18.
The kinetic behavior of heterogeneous microbial populations was studied in a continuous flow completely mixed reactor operated at various dilution rates. Glucose was used as the growth-limiting nutrient. The physiological growth parameters for cells harvested from continuous flow reactors were determined using batch experiments. It, was found that the growth parameters, maximum growth rate (μm), saturation constant (ks), and cell yield (Y) vary for each dilution rate, and cannot be considered as precise constants in depicting the kinetic behavior of heterogeneous populations. In addition, it was found that the yield coefficients obtained from batch experiments were always lower than those obtained from continuous flow experiments. Levels of substrate and biological solids calculated for different dilution rates using growth constants from batch experiments did not agree with the experimental values observed in steady-state experiments. However, when the yield values from, the continuous flow experiments were used in conjunction with batch values for μm and ks the theoretical and experimental dilute-out curves agreed fairly closely (within the range needed for engineering prediction) until the culture began to wash out of the unit. In general, the data substantiated the use of the single phase relationship between growth rate and substrate concentration described by the Monod equation, μ = μmS/(ks + s). 相似文献
19.
Fontana RC Salvador S Silveira MM 《Journal of industrial microbiology & biotechnology》2005,32(8):371-377
The solid-state production of endo- and exo-polygalacturonases (PG) by Aspergillus niger was studied in a media containing wheat bran, salts, and different citric pectin and/or glucose concentrations. Kinetic analysis
of the process indicated that the formation of PG and the growth of A. niger are associated processes. By increasing citric pectin from 0 to 16% (w/w), the maximum A. niger concentration (X
m) was raised from 94 to 121 mg/g dry medium suggesting that pectin can be used by A. niger as a growth substrate besides its role as an inducer. With 16% (w/w) pectin, 281 U exo-PG/gdm and 152 U endo-PG/gdm were
obtained. Otherwise, pectin concentrations from 20 to 30% (w/w) hindered both production and growth. A. niger concentrations of 108–113 mg/gdm were achieved in runs with glucose from 5 to 12% (w/w), whereas at 16 and 20% (w/w) glucose,
lower X
m values (ca. 100 mg/gdm) were measured. The addition of glucose to the wheat bran medium, up to 10% (w/w) led to maximum endo-PG
titers slightly lower than those found in the absence of glucose. Nevertheless, exo-PG formation in these media was strongly
increased and activities over 370 U/gdm were achieved. The results suggest that in experiments with pectin concentrations
until 16% (w/w), exo-PG production was repressed by pectin-degradation products although these same substances had favored
biomass growth. When glucose concentrations over 10% (w/w) were added to the media, the maximum activities of both enzymes
decreased drastically, suggesting that glucose at high concentrations also exerts a repressive effect on PG production. 相似文献
20.
Determination of the apparent pK
a's of purified carboxymethylcellulases fromAspergillus niger andCellulomonas biazotea at different temperatures and in the presence of dioxane indicated two side chain carboxyl groups which controlled the limiting
rate in both organisms. The thermostability of both enzymes slightly decreased with increasing pH from 5 to 7.5 but was unaffected
in the presence of 0.5 mmol/L Mn2+. The CMCase fromC. biazotea had an activation energy of 35 kJ/mol and a half-life of 89 min in the presence of 8 mol/L urea at 40°C. The half-life of
CMCase fromA. niger in 8 mol/L urea and at 37°C was 125 min as determined by a 0–9 mol/L transverse urea gradient PAGE. The CMCases fromA. niger andC. biazotea had the same thermostabilities in the absence of CMC although the enzyme from the former was more thermostable in the presence
of the substrate. The CMCase fromA. niger was also more efficient in hydrolyzing CMC than the enzyme fromC. biazotea. 相似文献