共查询到20条相似文献,搜索用时 578 毫秒
1.
Silvana T. Silveira Melissa S. Oliveira Jorge A. V. Costa Susana J. Kalil 《Applied biochemistry and biotechnology》2006,128(2):131-139
Glucoamylase production by Aspergillus niger in solid-state fermentation was optimized using factorial design and response surface techniques. The variables evaluated
were pH and bed thickness in tray, having as response enzyme production and productivity. The bed thickness in tray was the
most significant variable for both responses. The highest values for glucoamylase production occurred using pH 4.5 and bed
thickness in the inferior limits at 2.0–4.2 cm. For productivity, the optimal conditions were at pH 4.5 as well and bed thickness
from 4.4 to 7.5 cm. The optimal conditions for glucoamylase production while obtaining high activity without loss of productivity
were pH 4.5 and bed thickness in tray from 4.0 to 4.5 cm, which resulted in an enzyme production of 695 U/g and productivity
of 5791 U/h. 相似文献
2.
The marine yeast strain Kodamea ohmeri BG3 isolated from the gut of a marine fish (Hexagrammes otakii) was found to secrete a large amount of phytase into the medium. The crude phytase produced by this marine yeast showed the
highest activity at pH 5.0 and 65 °C. The optimal medium for phytase production contained oat 10.0 g/l, ammonium sulfate 15.0 g/l,
glucose 30 g/l, and NaCl 20.0 g/l, while the optimal cultivation conditions for phytase production were pH 5.0, a temperature
of 28 °C, and a shaking speed of 170 rpm. Under the optimal conditions, over 557.9 mU/ml of phytase activity was produced
within 72 h of fermentation at the shake flask level. This is a very high level of phytase activity produced by yeasts. We
think that the medium and process for phytase production by the marine yeast strain were very simple, and such marine yeast
from the gut of natural marine fish may have a potential application in the maricultural industry and marine environmental
protection. The results demonstrate that phytate was actively degraded by the crude phytase within a short period. 相似文献
3.
Production of chitinolytic enzymes with Trichoderma longibrachiatum IMI 92027 in solid substrate fermentation 总被引:1,自引:0,他引:1
Kovacs K Szakacs G Pusztahelyi T Pandey A 《Applied biochemistry and biotechnology》2004,118(1-3):189-204
Thirty Trichoderma strains representing 15 species within the genus were screened for extracellular production of chitinolytic enzymes in solid
substrate fermentation. Trichoderma longibrachiatum IMI 92027 (ATCC 36838) gave the highest yield (5.0 IU/g of dry matter of substrate) after 3 d of fermentation on wheat bran-crude
chitin (9:1 mixture) medium. The optimal moisture content (66.7%), chitin content (20%), initial pH of the medium (2.0–5.0),
and time course (5 d) of solid substrate fermentation were determined for strain IMI 92027. Cellulase, xylanase, α-amylase,
and β-xylosidase activities were also detected. The pH and temperature optima of the chitinase complex of T. longibrachiatum IMI 92027 were 4.5 and 55°C, respectively. The enzyme totally lost its activity at 70°C in 5 min in the absence of the substrate
but retained about 15% of its initial activity even at 70°C after a 60-min incubation in the presence of solid substrate fermentation
solids. Purification of protein extract from the solid substrate fermentation material revealed high chitinolytic activities
between pI 5.9 and 4.8, where N-acetyl-β-d-hexosaminidase and chitinase peaks have been found in the same pI range. Two chitinases of 43.5 and 30 kDa were purified at acidic pI. 相似文献
4.
To understand the differences in production and secretion patterns between plasmid-harboring and chromosome-integrated recombinant
yeasts, the two recombinant Saccharomyces cerevisiae yeasts, containing the structural glucoamylase STA gene and the SUC2 promoter, were investigated. Both systems were regulated by glucose concentration in the culture broth. First, the glucoamylase
activity per gene copy number of the chromosome-integrated recombinant yeast was 2.8- to 5.6-fold higher than that of the
plasmid-harboring recombinant yeast. Overburdened owing to high copy number, the plasmid-harboring recombinant yeast gave
lower glucoamylase activity per gene copy number. Second, the efficiency of signal sequence was compared; the secretion efficiency
of glucoamylase in the plasmid-harboring recombinant yeast was higher than that in the chromosome-integrated recombinant yeast
at 96 h of cultivation (74 vs 65%). We postulated that the higher level of secretion efficiency of the plasmid-harboring recombinant
yeast resulted because the production level did not reach the capacity of the secretory apparatus of the host yeast. However,
the specific secretion rate was much higher in the chromosome-integrated recombinant yeast even though the final secretion
efficiency was lower. The lower secretion rate in the plasmid-harboring recombinant yeast could be explained by an adverse
effect caused by higher production rate. Finally, the optimal glucose concentration for glucoamylase production in the chromosome-integrated
recombinant yeast culture was lower than that in the plasmid-harboring recombinant yeast culture owing to gene dosage effect. 相似文献
5.
Byoung Chul Park Sukhoon Koh Changsoo Chang Se Won Suh Dae-Sil Lee Si Myung Byun 《Applied biochemistry and biotechnology》1997,62(1):15-27
The gene encoding xylose isomerase (xylA) was cloned fromThermus flavus AT62 and the DNA sequence was determined. ThexylA gene encodes the enzyme xylose isomerase (XI orxylA) consisting of 387 amino acids (calculated Mr of 44,941). Also, there was a partial xylulose kinase gene that was 4 bp overlapped
in the end of XI gene. The XI gene was stably expressed inE. coli under the control oftac promoter. XI produced inE. coli was simply purified by heat treatment at 90°C for 10 min and column chromatography of DEAE-Sephacel. The Mr of the purified
enzyme was estimated to be 45 kDa on SDS-polyacrylamide gel electrophoresis. However, Mr of the cloned XI was 185 kDa on native
condition, indicating that the XI consists of homomeric tetramer. The enzyme has an optimum temperature at 90°C. Thermostability
tests revealed that half life at 85°C was 2 mo and 2 h at 95°C. The optimum pH is around 7.0, close to where by-product formation
is minimal. The isomerization yield of the cloned XI was about 55% from glucose, indicating that the yield is higher than
those of reported enzymes. The Km values for various sugar substrates were calculated as 106 mM for glucose. Divalent cations
such as Mn2+, Co2+, and Mg2+ are required for the enzyme activity and 100 mM EDTA completely inhibited the enzyme activity. 相似文献
6.
Mahesh S. Krishnan Nhuan P. Nghiem Brian H. Davison 《Applied biochemistry and biotechnology》1999,78(1-3):359-372
The production of ethanol from industrial dry-milled corn starch was studied in a laboratory-scale fluidized-bed bioreactor using immobilized biocatalysts. Saccharification and fermentation were carried out either simultaneously or separately. Simultaneous saccharification and fermentation (SSF) experiments were performed using small, uniform κ-carrageenan beads (1.5–2.5 mm in diameter) of co-immobilized glucoamylase and Zymomonas mobilis. Dextrin feeds obtained by the hydrolysis of 15% drymilled corn starch were pumped through the bioreactor at residence times of 1.5–4h. Single-pass conversion of dextrins ranged from 54–89%, and ethanol concentrations of 23–36 g/L were obtained at volumetric productivities of 9–15 g/L-h. Very low levels of glucose were observed in the reactor, indicating that saccharification was the rate-limiting step. In separate hydrolysis and fermentation (SHF) experiments, dextrin feed solutions of 150–160 g/L were first pumped through an immobilized-glucoamylase packed column. At 55°C and a residence time of 1 h, greater than 95% conversion was obtained, giving product streams of 162–172 g glucose/L. These streams were then pumped through the fluidized-bed bioreactor containing immobilized Z. mobilis. At a residence time of 2 h, 94% conversion and ethanol concentration of 70 g/L were achieved, resulting in an overall process productivity of 23 g/L-h. Atresidence times of 1.5 and 1 h, conversions of 75 and 76%, ethanol concentrations of 49 and 47 g/L, and overall process productivities of 19 and 25 g/L-h, respectively, were achieved. 相似文献
7.
S. S. Deshmukh M. Dutta Choudhury V. Shankar 《Applied biochemistry and biotechnology》1993,42(2-3):95-104
Partially purified glucose isomerase fromStreptomyces thermonitrificans when coupled to glutaraldehyde-activated Indion 48-R, retained 30–40% activity of the soluble enzyme. However, an approximately
twofold increase in the activity could be achieved by binding the enzyme in the presence of glucose. Binding the enzyme to
matrices presaturated with either glucose or fructose and influence of lysine modification on the activity of the soluble
enzyme revealed that the comparatively low activity observed in case of the enzyme bound in the absence of substrate is the
result of the nonspecific binding of either substrate or product to the matrix. Immobilization did not affect the pH and temperature
optima of the enzyme, but it lowered the temperature stability. Immobilization resulted in a marginal increase in theK
m
and a threefold decrease in theV
max
. Substrate concentrations as high as 36% glucose could be converted to 18.5% fructose in 5 h, at pH 7.0 and 70‡C. The bound
enzyme, however, showed inferior stability to repeated use and lost approx 40% of its initial activity after five cycles of
use. Indion 48-R bound glucose isomerase could be stored, in wet state, for 30 d without any apparent loss in its initial
activity. 相似文献
8.
A new high polygalacturonase (PG)-producing Kluyveromyces marxianus strain was isolated from coffee wet-processing wastewater. PG production in this strain is not repressed in the presence
of 100g/L of glucose and, being growth-associated, reached its maximum accumulation in the culture medium at the beginning
of the stationary phase. Oxygen and galacturonic acid negatively regulated enzyme synthesis, and glucose as the carbon source
afforded better enzyme yields than lactose. The data reported here show that this strain exhibits the highest index of PG
production among the wild-type strains reported so far (18.8U/mL). PG was readily purified by ion-exchange chromatography
on SP-Sepharose FF. The activity corresponded to a single protein with an M
r of 41.7 kDa according to sodium dodecyl sulfate polyacrylamide gel electrophoresis. The enzyme was stable in the pH range
of 3.0–5.0 and displayed an optimal temperature of 55°C; it showed a typical endo-splitting way of substrate hydrolysis and exhibited a fair degree of activity on pectin with a high degree of esterification. 相似文献
9.
Rosa S. M. A. Felipe M. G. A. Silva S. S. Vitolo M. 《Applied biochemistry and biotechnology》1998,(1):127-135
The effect of pH, time of fermentation, and xylose and glucose concentration on xylitol production, cell growth, xylose reductase
(XR), and xylitol dehydrogenase (XD) activities ofCandida guilliermondii FTI 20037 were determined. For attaining XR and XD activities of 129-2190 U/mg of protein and 24-917 U/mg of protein, respectively,
the cited parameters could vary as follows: initial pH: 3.0-5.0; xylose: 15-60 g/L; glucose: 0-5 g/L; and fermentation time:
12-24 h. Moreover, the high XR and XD activities occurred when the xylitol production by the yeast was less than 19.0 g/L. 相似文献
10.
Wei-Cho Huang David E. Ramey Shang-Tian Yang 《Applied biochemistry and biotechnology》2004,115(1-3):887-898
We explored the influence of dilution rate and pH in continuous cultures of Clostridium acetobutylicum. A 200-mL fibrous bed bioreactor was used to produce high cell density and butyrate concentrations at pH 5.4 and 35°C. By
feeding glucose and butyrate as a cosubstrate, the fermentation was maintained in the solventogenesis phase, and the optimal
butanol productivity of 4.6g/(L h) and a yield of 0.42 g/g were obtained at a dilution rate of 0.9h−1 and pH 4.3. Compared to the conventional acetone-butanol-ethanol fermentation, the new fermentation process greatly improved
butanol yield, making butanol production from corn an attractive alternative to ethanol fermentation. 相似文献
11.
An extracellular xylanase produced by a Mexican Aspergillus strain was purified and characterized. Aspergillus sp. FP-470 was able to grow and produce extracellular xylanases on birchwood xylan, oat spelt xylan, wheat straw, and corncob,
with higher production observed on corncob. The strain also produced enzymes with cellulase, amylase, and pectinase activities
on this substrate. A 22-kDa endoxylanase was purified 30-fold. Optimum temperature and pH were 60°C and 5.5, respectively,
and isoelectric point was 9.0. The enzyme has good stability from pH 5.0 to 10.0 retaining >80% of its original activity within
this range. Half-lives of 150 min at 50°C and 6.5 min at 60°C were found. K
m
and activation energy values were 3.8 mg/mL and 26 kJ/mol, respectively, using birch wood xylan as substrate. The enzyme
showed a higher affinity for 4-O-methyl-d-glucuronoxylan with a K
m
of 1.9 mg/mL. The enzyme displayed no activity toward other polysaccharides, including cellulose. Baking trials were conducted
using the crude filtrate and purified enzyme. Addition of both preparations improved bread volume. However, addition of purified
endoxylanase caused a 30% increase in volume over the crude extract. 相似文献
12.
Thermomucor indicae-seudaticae, a glucoamylase-producing thermophilic mould, was mutagenised using nitrous acid and gamma (60Co) irradiation in a sequential manner to isolate deregulated mutants for enhanced production of glucoamylase. The mutants
were isolated on Emerson YpSs agar containing a non-metabolisable glucose analogue 2-deoxy-d-glucose (2-DG) for selection. The preliminary screening for glucoamylase production using starch–iodine plate assay followed
by quantitative confirmation in submerged fermentation permitted the isolation of several variants showing varying levels
of derepression and glucoamylase secretion. The mutant strain T. indicae-seudaticae CR19 was able to grow in the presence of 0.5 g l−1 2-DG and produced 1.8-fold higher glucoamylase. As with the parent strain, glucoamylase production by T. indicae-seudaticae CR19 in 250-ml Erlenmeyer flasks attained a peak in 48 h of fermentation, showing higher glucoamylase productivity (0.67 U
ml−1 h−1) than the former (0.375 U ml−1 h−1). A large-scale cultivation in 5-l laboratory bioreactor confirmed similar fermentation profiles, though the glucoamylase
production peak was attained within 36 h attributable to the better control of process parameters. Although the mutant grew
slightly slow in the presence of 2-DG and exhibited less sporulation, it showed faster growth on normal Emerson medium with
a higher specific growth rate (0.138 h−1) compared to the parent strain (0.123 h−1). The glucoamylase produced by both strains was optimally active at 60 °C and pH 7.0 and displayed broad substrate specificity
by cleaving α-1,4- and α-1,6-glycosidic linkages in starch, amylopectin, amylose and pullulan. Improved productivity and higher
specific growth rate make T. indicae-seudaticae CR19 a useful strain for glucoamylase production. 相似文献
13.
Functional expression of a β-d-1,4 glucanase-encoding gene (egl1) from a filamentous fungus was achieved in both Escherichia coli and Saccharomyces cerevisiae using a modified version of pRS413. Optimal activity of the E. coli-expressed enzyme was found at incubation temperatures of 60°C, whereas the enzyme activity was optimal at 40°C when expressed
by S. cerevisiae. Enzyme activity at different pH levels was similar for both bacteria and yeast, being highest at 5.0. Yeast expression resulted
in a highly glycosylated protein of approx 60 kDa, compared to bacterial expression, which resulted in a protein of 30 kDa.
The hyperglycosylated protein had reduced enzyme activity, indicating that E. coli is a preferred vehicle for production scale-up. 相似文献
14.
Sarubbo LA Marçal MC Neves ML Silva MP Porto AL Campos-Takaki GM 《Applied biochemistry and biotechnology》2001,95(1):59-67
The yeast Candida lipolytica IA 1055 produced an inducible extracellular emulsification activity while utilizing glucose at different concentrations as
carbon source during batch fermentation at 27°C. In all glucose concentrations studied, maximum production of emulsification
activity was detected in the stationary phase of growth, after pH reached minimal values. The bioemulsifier isolated was a
complex biopolymer constituting proteins, carbohydrates, and lipids. The results obtained in this work show that the biosynthesis
of a bioemulsifier is not simply a prerequisite for the degradation of extracellular hydrocarbon. 相似文献
15.
Marcio Antonio Mazutti Aline Skrowonski Gabriela Boni Giovani Leone Zabot Marceli Fernandes Silva Débora de Oliveira Marco Di Luccio Francisco Maugeri Filho Maria Isabel Rodrigues Helen Treichel 《Applied biochemistry and biotechnology》2010,160(3):682-693
Inulinase belongs to an important class of enzymes as it can be used to produce high-fructose syrups by enzymatic hydrolysis of inulin and fructooligosaccharides, which has been used as functional food. This work aimed to carry out a partial characterization of the crude enzymatic extract of two different inulinases, obtained by solid-state fermentation (SSF) and submerged fermentation (SmF), using agroindustrial residues as substrates. The crude enzymatic extract obtained by SmF showed an optimal pH and temperature for hydrolytic activity of 4.5 and 55?°C, respectively; and that obtained by SSF conducted to optimal pH and temperature of 5.0 and 55?°C, respectively. Both enzymes presented high thermostability, with a D value of 230.4 h and 123.1 h for SmF and SSF, respectively. The inulinase produced by SmF showed highest stability at pH?4.4, while inulinase obtained by SSF was more stable at pH?4.8. The results showed that inulinase obtained by SmF is less susceptible to pH effect and the inulinase obtained by SSF is more resistant to higher temperatures. 相似文献
16.
This work represents a continuation of our investigation into environmental conditions that promote lactic acid synthesis
by Zymomonas mobilis. The characteristic near theoretical yield of ethanol from glucose by Z. mobilis can be compromised by the synthesis of d- and l-lactic acid. The production of lactic acid is exacerbated by the following conditions: pH 6.0, yeast extract, and reduced
growth rate. At a specific growth rate of 0.048/h, the average yield of dl-lactate from glucose in a yeast extract-based medium at pH 6.0 was 0.15 g/g. This represents a reduction in ethanol yield
of about 10% relative to the yield at a growth rate of 0.15/h. Very little lactic acid was produced at pH 5.0 or using a defined
salts medium (without yeast extract) Under permissive and comparable culture conditions, a tetracycline-resistant, d-ldh negative mutant produced about 50% less lactic acid than its parent strain Zm ATCC 39676. d-lactic acid was detected in the cell-free spent fermentation medium of the mutant, but this could be owing to the presence
of a racemase enzyme. Under the steady-state growth conditions provided by the chemostat, the specific rate of glucose consumption
was altered at a constant growth rate of 0.075/h. Shifting from glucose-limited to nitrogen-limited growth, or increasing
the temperature, caused an increase in the specific rate of glucose catabolism. There was good correlation between an increase
in glycolytic flux and a decrease in lactic acid yield from glucose. This study points to a mechanistic link between the glycolytic
flux and the control of end-product glucose metabolism. Implications of reduced glycolytic flux in pentose-fermenting recombinant
Z. mobilis strains, relative to increased byproduct synthesis, is discussed. 相似文献
17.
Production of 2-ketogluconic acid in batch fermentation was investigated.Acetobacter pasteurianus ATCC 6438, which produces selectively 2-ketogluconic acid only, was used. The optimal pH for glucose dehydrogenation to gluconate
by resting cells was 5.0 and for gluconate dehydrogenation to 2-ketogluconate 4.25. When glucose medium was used, the 89%
yield was achieved after 90 h. For the optimal productivity, medium containing glucose and gluconate with the molar glucose:gluconate
ratio 7.4 was proposed, and the yield of 92% after 56 h was achieved. This composition of medium led to the elevation of dissolved
oxygen concentration during fermentation. It consequently resulted in elevated gluconate dehydrogenase activity being discussed
as the rate-limiting activity of the batch production. 相似文献
18.
Rey MW Brown KM Golightly EJ Fuglsang CC Nielsen BR Hendriksen HV Butterworth A Xu F 《Applied biochemistry and biotechnology》2003,111(3):153-166
Thielavia terrestris is a soil-borne thermophilic fungus whose molecular/cellular biology is poorly understood. Only a few genes have been cloned
from the Thielavia genus. We detected an extracellular glucoamylase in culture filtrates of T. terrestris and cloned the corresponding glaA gene. The coding region contains five introns. Based on the amino acid sequence, the glucoamylase was 65% identical to Neurospora crassa glucoamylase. Sequence comparisons suggested that the enzyme belongs to the glycosyl hydrolase family 15. The T. terrestris glaA gene was expressed in Aspergillus oryzae under the control of an A. oryzae α-amylase promoter and an Aspergillus niger glucoamylase terminator. The 75-kDa recombinant glucoamylase showed a specific activity of 2.8 μmol/(min·mg) with maltose
as substrate. With maltotriose as a substrate, the enzyme had an optimum pH of 4.0 and an optimum temperature of 60°C. The
enzyme was stable at 60°C for 30 min. The K
m
and k
cat
of the enzyme for maltotriose were determined at various pHs and temperatures. At 20°C and pH 4.0, the enzyme had a K
m
of 0.33±0.07 mM and a k
cat
of (5.5±0.5)×103 min−1 for maltotriose. The temperature dependence of k
cat
/K
m
indicated an activation free energy of 2.8 kJ/mol across the range of 20–70°C. Overall, the enzyme derived from the thermophilic
fungus exhibited properties comparable with that of its homolog derived from mesophilic fungi. 相似文献
19.
Aline Costa de Freitas Bruna Escaramboni Ana Flávia Azevedo Carvalho Valéria Marta Gomes de Lima Pedro de Oliva-Neto 《Chemical Papers》2014,68(4):442-450
Amylases from Rhizopus oryzae and Rhizopus microsporus var. oligosporus were obtained using agro-industrial wastes as substrates in submerged batch cultures. The enzymatic complex was partially characterised for use in the production of glucose syrup. Type II wheat flour proved better than cassava bagasse as sole carbon source for amylase production. The optimum fermentation condition for both microorganisms was 96 hours at 30°C and the amylase thus produced was used for starch hydrolysis. The product of the enzymatic hydrolysis indicated that the enzyme obtained was glucoamylase, only glucose as final product was attained for both microorganisms. R. oligosporus was of greater interest than R. oryzae for amylase production, taking into account enzyme activity, cultivation time, thermal stability and pH range. Glucose syrup was produced using concentrated enzyme and 100 g L?1 starch in a 4 hours reaction at 50°C. The bioprocess studied can contribute to fungus glucoamylase production and application. 相似文献
20.
Grethlein A. J. Worden R. M. Jain M. K. Datta R. 《Applied biochemistry and biotechnology》1990,(1):875-884
Continuous, steady-state fermentations using carbon monoxide gas as the sole carbon and energy source have been achieved with
the CO strain ofButyribacterium methylotrophicum. Fermentation pH was found to regulate carbon monoxide metabolism over the pH range of 6.8 to 5.0. Cell growth diminished
at low pH, with washout occurring at pH 5.0. As observed previously in batch culture, lower pH values favored production of
butyrate over acetate. The mechanism responsible for this trend is currently being investigated by quantification of key intracellular
enzyme activities.
At low pH values, direct, steady-state fermentation of carbon monoxide to alcohols has been verified. Of major significance
is the production of butanol from carbon monoxide in pure culture. This newly identified pathway provides a potential mechanism
for direct bioconversion of synthesis gas to butanol. 相似文献