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1.
Valquiria B. Damiano Richard Ward Eleni Gomes Heloiza Ferreira Alves-Prado Roberto Da Silva 《Applied biochemistry and biotechnology》2006,129(1-3):289-302
The alkalophilic bacteria Bacillus licheniformis 77-2 produces significant quantities of thermostable cellulase-free xylanases. The crude xylanase was purified to apparent
homogeneity by gel filtration (G-75) and ionic exchange chromatography (carboxymethyl sephadex, Q sepharose, and Mono Q),
resulting in the isolation of two xylanases. The molecular masses of the enzymes were estimated to be 17 kDa (X-I) and 40
kDa (X-II), as determined by SDS-PAGE. The K
m and V
max values were 1.8 mg/mL and 7.05 U/mg protein (X-I), and 1.05 mg/mL and 9.1 U/mg protein (X-II). The xylanases demonstrated
optimum activity at pH 7.0 and 8.0–10.0 for xylanase X-I and X-II, respectively, and, retained more than 75% of hydrolytic
activity up to pH 11.0. The purified enzymes were most active at 70 and 75°C for X-I and X-II, respectively, and, retained
more than 90% of hydrolytic activity after 1 h of heating at 50°C and 60°C for X-I and X-II, respectively. The predominant
products of xylan hydrolysates indicated that these enzymes were endoxylanases. 相似文献
2.
Xylanase from Bacillus pumilus strain MK001 was immobilized on different matrices following varied immobilization methods. Entrapment using gelatin (GE)
(40.0%), physical adsorption on chitin (CH) (35.0%), ionic binding with Q-sepharose (Q-S) (45.0%), and covalent binding with
HP-20 beads (42.0%) showed the maximum xylanase immobilization efficiency. The optimum pH of immobilized xylanase shifted
up to 1.0 unit (pH 7.0) as compared to free enzyme (pH 6.0). The immobilized xylanase exhibited higher pH stability (up to
28.0%) in the alkaline pH range (7.0–10.0) as compared to free enzyme. Optimum temperature of immobilized xylanase was observed
to be 8 °C higher (68.0 °C) than free enzyme (60.0 °C). The free xylanase retained 50.0% activity, whereas xylanase immobilized
on HP-20, Q-S, CH, and GE retained 68.0, 64.0, 58.0, and 57.0% residual activity, respectively, after 3 h of incubation at
80.0 °C. The immobilized xylanase registered marginal increase and decrease in K
m and V
max values, respectively, as compared to free enzyme. The immobilized xylanase retained up to 70.0% of its initial hydrolysis
activity after seven enzyme reaction cycles. The immobilized xylanase was found to produce higher levels of high-quality xylo-oligosaccharides
from birchwood xylan, indicating its potential in the nutraceutical industry. 相似文献
3.
Maalej I Belhaj I Masmoudi NF Belghith H 《Applied biochemistry and biotechnology》2009,158(1):200-212
A thermostable xylanase from a newly isolated thermophilic fungus Talaromyces thermophilus was purified and characterized. The enzyme was purified to homogeneity by ammonium sulfate precipitation, diethylaminoethyl
cellulose anion exchange chromatography, P-100 gel filtration, and Mono Q chromatography with a 23-fold increase in specific
activity and 17.5% recovery. The molecular weight of the xylanase was estimated to be 25kDa by sodium dodecyl sulfate–polyacrylamide
gel electrophoresis and gel filtration. The enzyme was highly active over a wide range of pH from 4.0 to 10.0. The relative
activities at pH5.0, 9.0, and 10.0 were about 80%, 85.0%, and 60% of that at pH7.5, respectively. The optimum temperature
of the purified enzyme was 75°C. The enzyme showed high thermal stability at 50°C (7days) and the half-life of the xylanase
at 100°C was 60min. The enzyme was free from cellulase activity. K
m and V
max values at 50°C of the purified enzyme for birchwood xylan were 22.51mg/ml and 1.235μmol min−1 mg−1, respectively. The enzyme was activated by Ag+, Co2+, and Cu2+; on the other hand, Hg2+, Ba2+, and Mn2+ inhibited the enzyme. The present study is among the first works to examine and describe a secreted, cellulase-free, and
highly thermostable xylanase from the T. thermophilus fungus whose application as a pre-bleaching aid is of apparent importance for pulp and paper industries. 相似文献
4.
Two xylanases from the crude culture filtrate of Penicillium sclerotiorum were purified to homogeneity by a rapid and efficient procedure, using ion-exchange and molecular exclusion chromatography.
Molecular masses estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis were 23.9 and 33.1 kDa for xylanase
I and II, respectively. The native enzymes’ molecular masses of 23.8 and 30.8 kDa were estimated for xylanase I and II, respectively,
by molecular exclusion chromatography. Both enzymes are glycoproteins with optimum temperature and pH of 50 °C and pH 2.5
for xylanase I and 55 °C and pH 4.5 for xylanase II. The reducing agents β-mercaptoethanol and dithio-treitol enhanced xylanase
activities, while the ions Hg2+ and Cu2+ as well the detergent SDS were strong inhibitors of both enzymes, but xylanase II was stimulated when incubated with Mn2+. The K
m value of xylanase I for birchwood xylan and for oat spelt xylan were 6.5 and 2.6 mg mL−1, respectively, whereas the K
m values of xylanase II for these substrates were 26.61 and 23.45 mg mL−1. The hydrolysis of oat spelt xylan by xylanase I released xylobiose and larger xylooligosaccharides while xylooligosaccharides
with a decreasing polymerization degree up to xylotriose were observed by the action of xylanase II. The present study is
among the first works to examine and describe an extracellular, highly acidophilic xylanase, with an unusual optimum pH at
2.5. Previously, only one work described a xylanase with optimum pH 2.0. This novel xylanase showed interesting characteristics
for biotechnological process such as feed and food industries. 相似文献
5.
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
6.
Arief Budi Witarto Takafumi Ohtera Koji Sode 《Applied biochemistry and biotechnology》1999,77(1-3):159-168
We have previously reported that a chimeric pyrroloquinoline quinone (PQQ) glucose dehydrogenase (GDH), E97A3, which was made
up of 97% of Escherichia coli PQQGDH sequence and 3% of Acinetobacter calcoaceticus PQQGDH, showed increased thermal stability compared with both parental enzymes. Site-directed mutagenesis studies were carried
out in order to investigate the role of amino-acid substitution at the C-terminal region, Ser 771, of a chimeric PQQGDHs on
their thermal stability. A series of Ser 771 substitutions of a chimeric PQQGDH, E99A1, confirmed that hydrophobic interaction
governs the thermal stability of the chimeric enzymes. Comparison of the thermal denaturation of E. coli PQQGDH and E97A3 followed by far-ultraviolet (UV) circular dichroism (CD) spectroscopy revealed that E97 A3 acquired stability
at the first step of denaturation, which is reversible, and where no significant secondary structure change was observed.
These results suggested that the interaction between C-terminal and N-terminal regions may play a crucial role in maintaining
the overall structure of β-propeller proteins. 相似文献
7.
Hongge Chen Liangwei Liu Shuai Lv Xinyu Liu Mingdao Wang Andong Song Xincheng Jia 《Applied biochemistry and biotechnology》2010,162(1):24-32
Dialdehyde starch (DAS) was used as a novel coupling agent to prepare chitosan carrier to immobilize the xylanase from Aspergillus niger A-25. Compared with glutaraldehyde-cross-linked chitosan (CS-GA) and pure chitosan beads, the DAS-cross-linked chitosan (CS-DAS)
beads exhibited the highest xylanase activity recovery. The DAS adding amount and cross-linking time in CS-DAS preparation
process were optimized with respect to activity recovery to the values of 1.0 g (6.7% w/v concentration) and 16 h, respectively. The optimum temperature of both the CS-DAS- and CS-GA-immobilized xylanase was observed
to be 5 °C higher than that of free enzyme (50 °C). The CS-DAS-immobilized xylanase had the highest thermal and storage stability
as compared to the CS-GA-immobilized and free xylanase. The apparent K
m and V
max values of the CS-DAS-immobilized xylanase were estimated to be 1.29 mg/ml and 300.7 μmol/min/mg protein, respectively. The
CS-DAS-immobilized xylanase could produce from birchwood xylan high-quality xylo-oligosaccharides, mainly composed of xylotriose,
as free xylanase did. The proposed CS-DAS carrier was more advantageous over the CS-GA or pure chitosan carrier for xylanase
immobilization application. 相似文献
8.
Carvalho Andrade Carolina M. M. Aguiar Wilson Bucker Antranikian Garo 《Applied biochemistry and biotechnology》2001,91(1-9):655-669
Xylanases (EC3.2.1.8) catalyze the hydrolysis of xylan, the major constituent of hemicellulose. The use of these enzymes could
greatly improve the overall economics of processing lignocellulosic materials for the generation of liquid fuels and chemicals.
The hyperthermophilic archaeon Pyrodictium abyssi, which was originally isolated from marine hot abyssal sites, grows optimally at 97°C and is a prospective source of highly
thermostable xylanase. Its endoxylanase was shown to be highly thermostable (over 100 m in at 105°C) and active even at 110°C.
The growth of the deep-sea archaeon P. abyssi was investigated using different culture techniques. Among the carbohydrates used, beech wood xylan, birch wood glucuronoxylan
and the arabinoxylan from oats pelt appeared to be good inducers for endoxylanase and β-xylosidase production. The highest
production of arabinofuranosidase, however, was detected in the cell extracts after growth on xylose and pyruvate, indicating
that the intermediate of the tricarboxylic acid cycle acted as a nonrepressing carbon source for the production of thi enzyme.
Electron microscopic studies did not show a significant difference in the cell surface (e.g., xylanosomes) when P. abyssi cells were grown on different carbohydrates. The main kinetic parameters of the organism have been determined. The cell yield
was shown to be very low owing to incomplete substrate utilization, but a very high maximal specific growth rate was determined
(μmax=0.0195) at 90°C and pH 6.0. We also give information on the problems that arise during the fermentation of this hyperthermophilic
archaeon at elevated temperatures. 相似文献
9.
Taibi Z Saoudi B Boudelaa M Trigui H Belghith H Gargouri A Ladjama A 《Applied biochemistry and biotechnology》2012,166(3):663-679
An extracellular thermostable xylanase from a newly isolated thermophilic Actinomadura sp. strain Cpt20 was purified and characterized. Based on matrix-assisted laser desorption–ionization time-of-flight mass
spectrometry analysis, the purified enzyme is a monomer with a molecular mass of 20,110.13 Da. The 19 residue N-terminal sequence
of the enzyme showed 84% homology with those of actinomycete endoxylanases. The optimum pH and temperature values for xylanase
activity were pH 10 and 80 °C, respectively. This xylanase was stable within a pH range of 5–10 and up to a temperature of
90 °C. It showed high thermostability at 60 °C for 5 days and half-life times at 90 °C and 100 °C were 2 and 1 h, respectively.
The xylanase was specific for xylans, showing higher specific activity on soluble oat-spelt xylan followed by beechwood xylan.
This enzyme obeyed the Michaelis–Menten kinetics, with the K
m and k
cat values being 1.55 mg soluble oat-spelt xylan/ml and 388 min−1, respectively. While the xylanase from Actinomadura sp. Cpt20 was activated by Mn2+, Ca2+, and Cu2+, it was, strongly inhibited by Hg2+, Zn2+, and Ba2+. These properties make this enzyme a potential candidate for future use in biotechnological applications particularly in
the pulp and paper industry. 相似文献
10.
Dengeti Shrinivas Gunashekaran Savitha Kumar Raviranjan Gajanan Ramchandra Naik 《Applied biochemistry and biotechnology》2010,162(7):2049-2057
A highly thermostable alkaline xylanase was purified to homogeneity from culture supernatant of Bacillus sp. JB 99 using DEAE-Sepharose and Sephadex G-100 gel filtration with 25.7-fold increase in activity and 43.5% recovery.
The molecular weight of the purified xylanase was found to be 20 kDA by SDS-PAGE and zymogram analysis. The enzyme was optimally
active at 70 °C, pH 8.0 and stable over pH range of 6.0–10.0.The relative activity at 9.0 and 10.0 were 90% and 85% of that
of pH 8.0, respectively. The enzyme showed high thermal stability at 60 °C with 95% of its activity after 5 h. The K
m and V
max of enzyme for oat spelt xylan were 4.8 mg/ml and 218.6 μM min−1 mg−1, respectively. Analysis of N-terminal amino acid sequence revealed that the xylanase belongs to glycosyl hydrolase family
11 from thermoalkalophilic Bacillus sp. with basic pI. Substrate specificity showed a high activity on xylan-containing substrate and cellulase-free nature. The hydrolyzed product
pattern of oat spelt xylan on thin-layer chromatography suggested xylanase as an endoxylanase. Due to these properties, xylanase
from Bacillus sp. JB 99 was found to be highly compatible for paper and pulp industry. 相似文献
11.
B. Choudhury Preetika Aggarwal R. K. Gothwal Rahul Mantri M. K. Mohan P. Ghosh 《Applied biochemistry and biotechnology》2006,128(2):159-169
The efficiency of xylanase of Bacillus brevis BISR-062 as a prebleaching agent was evaluated on three nonwoody pulps at two different pH values (7.0 and 8.5). Crude xylanase
was found to have an optimum temperature and pH of 65–70°C and 7.0, respectively. The stability of the enzyme was determined
at two pH values (7.0 and 8.0), and it lost approx 50% of its activity at both values within 2 h at 50°C. However, the enzyme
was found to be effective as a prebleaching agent only with rice straw pulp. A maximum brightness gain of 6 points was obtained
with this pulp at pH 7.0. The strength properties of the rice straw pulp at pH 7.0 also improved as the result of enzyme treatment. 相似文献
12.
Daniela A. Bocchini Valquiria B. Damiano Eleni Gomes Roberto Da Silva 《Applied biochemistry and biotechnology》2003,106(1-3):393-401
The alkalophilic Bacillus circulans D1 was isolated from decayed wood. It produced high levels of extracellular cellulase-free xylanase. The enzyme was thermally
stable up to 60°C, with an optimal hydrolysis temperature of 70°C. It was stable over a wide pH range (5.5—10.5), with an
optimum pH at 5.5 and 80% of its activity at pH 9.0. This cellulase-free xylanase preparation was used to biobleach kraft
pulp. Enzymatic treatment of kraft pulp decreased chlorine dioxide use by 23 and 37% to obtain the same kappa number (κ number)
and brightness, respectively. Separation on Sephadex G-50 isolated three fractions with xylanase activity with distinct molecular
weights. 相似文献
13.
Penna Thereza Christina Vessoni Chiarini Eb Machoshvili Irene Alexeevna Ishii Marina Pessoa Adalberto 《Applied biochemistry and biotechnology》2002,98(1-9):791-802
The recombinant green fluorescent protein (gfp
uv
) was expressed by Escherichia coli DH5-α cells transformed with the plasmid pGFPuv. The gfp
uv
was selectively permeabilized from the cells in buffer solution (25 mM Tris-HCl, pH 8.0), after freezing (−70°C for 15 h), by four freeze (−20°C)/thaw cycles interlaid by sonication. The average
content of released gfp
uv
(experiment 2) was 7.76, 34.58, 39.38, 12.90, and 5.38%, for the initial freezing (−70°C) and the first, second, third and
fourth freeze/thaw cycles, respectively. Superfusion on freezing was observed between −11°C and −14°C, after which it reached
−20°C at 0.83°C/min. 相似文献
14.
Yihang Li Bo Zhang Xiang Chen Yiqun Chen Yunhe Cao 《Applied biochemistry and biotechnology》2010,160(5):1321-1331
The gene xynB from Aspergillus sulphureus encoding the endo-β-1,4-xylanase was de novo synthesized by splicing overlap extension polymerase chain reaction according
to Pichia pastoris protein’s codon bias. The synthetic DNA and wild-type DNA were placed under the control of a glyceraldehyde-3-phosphate dehydrogenase
gene promoter (GAP) in the constitutive expression vector plasmid pGAPzαA and electrotransformed into the P. pastoris X-33 strain, respectively. The transformants screened by Zeocin were able to constitutively secrete the xylanase in YPD liquid
medium. The maximum yield of the recombinant xylanase produced by the synthetic DNA was 105 U ml−1, which was about 5-fold higher than that by wild-type DNA under the flask culture at 28 °C for 3 days. The enzyme showed
optimal activity at 50 °C and pH 5.0. The residual activity remained above 90% after the recombinant xylanase was pretreated
in Na2HPO4–citric acid buffer (pH 2.4) for 2 h. The xylanase activity was significantly improved by Zn2+. These biochemical characteristics suggest that the recombinant xylanase has a prospective application in feed industry as
an additive. 相似文献
15.
Eduardo A Castro 《Chemistry Central journal》2007,1(1):1-5
Background
The use of immobilized enzymes for catalyzing various biotransformations is now a widely used approach. In recent years, cross-linked enzyme aggregates (CLEAs) have emerged as a novel and versatile biocatalyst design. The present work deals with the preparation of a CLEA from a commercial preparation, Pectinex? Ultra SP-L, which contains pectinase, xylanase and cellulase activities. The CLEA obtained could be used for any of the enzyme activities. The CLEA was characterized in terms of kinetic parameters, thermal stability and reusability in the context of all the three enzyme activities.Results
Complete precipitation of the three enzyme activities was obtained with n-propanol. When resulting precipitates were subjected to cross-linking with 5 mM glutaraldehyde, the three activities initially present (pectinase, xylanase and cellulase) were completely retained after cross-linking. The Vmax/Km values were increased from 11, 75 and 16 to 14, 80 and 19 in case of pectinase, xylanase and cellulase activities respectively. The thermal stability was studied at 50°C, 60°C and 70°C for pectinase, xylanase and cellulase respectively. Half-lives were improved from 17, 22 and 32 minutes to 180, 82 and 91 minutes for pectinase, xylanase and cellulase respectively. All three of the enzymes in CLEA could be reused three times without any loss of activity.Conclusion
A single multipurpose biocatalyst has been designed which can be used for carrying out three different and independent reactions; 1) hydrolysis of pectin, 2) hydrolysis of xylan and 3) hydrolysis of cellulose. The preparation is more stable at higher temperatures as compared to the free enzymes. 相似文献16.
To obtain extracellular and high-level expression of the Dictyoglomus thermophilum Rt46B.1 xylanase B gene, this gene was integrated into the α-amylase gene site of a host strain of Bacillus subtilis WB800. The extreme thermophile xylanase gene was successfully integrated and expressed in the host, measured at 24 ± 0.4 XUs/mL
in the Luria broth medium supernatant. The recombinant enzyme was purified by ammonium sulfate precipitation, anion exchange
chromatography, and gel filtration. The molecular mass and pI value of xylanase were estimated to be 24 kDa and 4.3, respectively. The optimal pH level and temperature of the purified
enzyme were 6.5 and 85 °C, respectively. Xylanase showed reasonable activity at temperatures up to 95 °C and remained stable
at 4 °C for 1 week. The purified enzyme retained most of its activity in 1 mM ethylenediaminetetraacetic acid or dithiothreitol
and 0.1% Tween-20 or Triton X-100. However, strong inhibition was observed in the presence of 5 mM Mn2+, 0.5% sodium dodecyl sulfate, Tween-20, or Triton X-100; a strong stimulating effect was also observed in the presence of
Fe2+. The K
m and V
max values of the recombinant xylanase for birchwood xylan were calculated to be 2.417 ± 0.36 mg/mL and 325 ± 41 μmol/min mg,
respectively. Xylanase was found to be useful in the prebleaching process of paper pulps. 相似文献
17.
A psychrotrophic fungus identified as Trichoderma sp. SC9 produced 36.7 U/ml of xylanase when grown on a medium containing corncob xylan at 20 °C for 6 days. The xylanase
was purified 37-fold with a recovery yield of 8.2%. The purified xylanase appeared as a single protein band on SDS-PAGE with
a molecular mass of approximately 20.5 kDa. The enzyme had an optimal pH of 6.0, and was stable over pH 3.5–9.0. The optimal
temperature of the xylanase was 42.5 °C and it was stable up to 35 °C at pH 6.0 for 30 min. The xylanase was thermolabile
with a half-life of 23.9 min at 45 °C. The apparent K
m
values of the xylanase for birchwood, beechwood, and oat-spelt xylans were found to be 3, 2.1, and 16 mg/ml respectively.
The xylanase hydrolyzed beechwood xylan and birchwood xylan to yield mainly xylobiose as end products. The enzyme-hydrolysed
xylotriose, xylotetraose, and xylopentose to produce xylobiose, but it hardly hydrolysed xylobiose. A xylanase gene (xynA) with an open reading frame of 669 nucleotide base pairs (bp), encoding 222 amino acids, from the strain was cloned and sequenced.
The deduced amino acid sequence of XynA showed 85% homology with Xyn2 from a mesophilic strain of Trichoderma viride. 相似文献
18.
Manchumas Hengsakul Prousoontorn Supranee Pantatan 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):39-46
Cyclodextrin glycosyltransferase (CGTase) isolated and purified from Paenibacillus sp. A11 was immobilized on various carriers by covalent linkage using bifunctional agent glutaraldehyde. Among tested carriers,
alumina proved to be the best carrier for immobilization. The effects of several parameters on the activation of the support
and on the immobilization of enzyme were optimized. The best preparation of immobilized CGTase retained 31.2% of its original
activity. After immobilization, the enzymatic properties were investigated and compared with those of the free enzyme. The
optimum pH of the immobilized CGTase was shifted from 6.0 to 7.0 whereas optimum temperature remained unaltered (60°C). Free
and immobilized CGTase showed similar pH stability profile but the thermal stability of the immobilized CGTase was 20% higher.
Kinetic data (K
M and V
max) for the free and immobilized enzymes were determined from the rate of β-CD formation and it was found that the immobilized
form had higher K
M and lower V
max. The immobilized CGTase also exhibited higher stability when stored at both 4°C and 25°C for 2 months. The enzyme immobilized
on alumina was further used in a batch production of 2-O-α-glucopyranosyl-l-ascorbic acid (AA-2G) from ascorbic acid and β-cyclodextrin. The yield of AA-2G was 2.92% and the immobilized CGTase retained
its activity up to 74.4% of the initial catalytic activity after being used for 3 cycles. The immobilized CGTase would have
a promising application in the production of various transglycosylated compounds and in the production of cyclodextrin by
the hydrolysis of starch. 相似文献
19.
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
20.
Penna Thereza Christina Vessoni Marques Marcelo Machoshvili Irena A. Ishii Marina 《Applied biochemistry and biotechnology》2002,98(1-9):539-551
Large-volume parenteral solutions were submitted to heat treatments after being inoculated with Bacillus stearothermophilus ATCC 7953 (T
r
=121°C) and Bacillus subtilis ATCC 9372 (T
r
=104.5°C) spores. The average decimal reduction time for B. stearothermophilus ranged from a D
121°C value of 1.31 to 3.14 min, in glucophysiologic and Ringer’s solutions respectively. For B. subtilis, D
104.5°C value increased from 0.69 to 1.37 min, in Ringer’s (pH=5.91) and 50% glucose (pH 3.05) solutions respectively. The z value ranged from 7.95°C (20% mannitol solution) to 13.14°C (50% glucose solution), corresponding to an activation energy
(Ea) of 81.48 and 49.30 kcal/mol, respectively. 相似文献