共查询到20条相似文献,搜索用时 31 毫秒
1.
Dastager SG Dayanand A Li WJ Kim CJ Lee JC Park DJ Tian XP Raziuddin QS 《Current microbiology》2008,57(6):638-642
Multiple proteases were produced and partially purified from an alkali-thermotolerant novel species of Streptomyces (i.e.,
Streptomyces gulbargensis DAS 131) after 48 h of growth at 45°C. The enzyme preparation exhibited activity over a broad range of pH (4–12) and temperature
(27–55°C). Optimum activity was observed at a pH of 9.0 and a temperature of 45°C. Starch and protease peptone was found to
be a good source of carbon and nitrogen to enhance the enzyme activity. Two active zones in the range of 19 to 35 kDa were
detected on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). 相似文献
2.
Junpei Zhou Pengjun Shi Rui Zhang Huoqing Huang Kun Meng Peilong Yang Bin Yao 《Journal of industrial microbiology & biotechnology》2011,38(4):523-530
A pH-stable and protease-resistant xylanase (XynB119) was identified from Streptomyces sp. TN119, a strain isolated from the gut luminal contents of longhorned beetle (Batocera horsfieldi) larvae. Using the GC TAIL-PCR method, the 1,026-bp coding gene (xynB119) with 67.3% GC content was successfully cloned and expressed in Escherichia coli. It encodes a 341-residue polypeptide with a calculated molecular mass of 35.9 kDa, including a putative 41-residue signal
peptide, a catalytic domain of glycosyl hydrolase (GH) family 11, a short Gly/Pro-rich linker, and a family 2 cellulose-binding
domain (CBM 2). The deduced amino acid sequence is most similar to (61.9% identity) an endo-1,4-β-xylanase from Streptomyces thermoviolaceus OPC-520. Purified recombinant XynB119 exhibited peak activity at 50°C and pH 7.0, remained stable over a broad pH range (retaining >70%
activity after incubation at pH 1.0–11.0 for 1 h at 37°C without substrate), had strong protease resistance (retaining >90%
activity after proteolytic treatment at 37°C for 1 h) and SDS resistance (at 100 mM). These properties make XynB119 promising
for application in the feed industry and valuable for basic research. Compared to r-XynB119, the r-XynB119 derivative without
CBM 2 and linker region (r-XynB119d) exhibited a decreased pH stability of >25% at extreme pHs (pH 1.0–3.0 and pH 11.0–12.0). 相似文献
3.
Two species of cold-temperate algae from the North Atlantic Ocean,Polyides rotundus andFurcellaria lumbricalis, were tested for growth and survival over a temperature range of −5 to 30 °C. In comparisons of eastern and western isolates,
bothF. lumbricalis, a North Atlantic endemic, andP. rotundus, a species having related populations in the North Pacific, were quite homogeneous.F. lumbricalis tolerated −5 to 25°C and grew well from 0 to 25°C, with optimal growth at 10–15 °C.P. rotundus tolerated −5 to 27°C, grew well from 5 to 25°C, and had a broad optimal range of 10–25°C. Both species tolerated 3 months
in darkness at 0°C. In neither case could any geographic boundary be explained in terms of lethal seasonal temperatures, suggesting
that these species are restricted in distribution by strict thermal and/or daylength requirements for reproduction. The hypothesis
that northern species are more homogeneous than southern taxa in terms of thermal tolerance was supported. A second hypothesis,
that disjunct cold-temperate species should be more variable than pan-Arctic species, was not supported. 相似文献
4.
A. Mandal S. Kar P. K. Das Mohapatra C. Maity B. R. Pati K. C. Mondal 《Applied Biochemistry and Microbiology》2011,47(3):250-255
An extracellular xylanase from the fermented broth of Bacillus cereus BSA1 was purified and characterized. The enzyme was purified to 3.43 fold through ammonium sulphate precipitation, DEAE cellulose
chromatography and followed by gel filtration through Sephadex-G-100 column. The molecular mass of the purified xylanse was
about 33 kDa. The enzyme was an endoxylanase as it initially degraded xylan to xylooligomers. The purified enzyme showed optimum
activity at 55°C and at pH 7.0 and remained reasonably stable in a wide range of pH (5.0–8.0) and temperature (40–65°C). The
K
m
and V
max
values were found to be 8.2 mg/ml and 181.8 μmol/(min mg), respectively. The enzyme had no apparent requirement of cofactors,
and its activity was strongly inhibited by Cu2+, Hg2+. It was also a salt tolerant enzyme and stable upto 2.5 M of NaCl and retained its 85% activity at 3.0 M. For stability and
substrate binding, the enzyme needed hydrophobic interaction that revealed when most surfactants inhibited xylanase activity.
Since the enzyme was active over wide range of pH, temperature and remained active in higher salt concentration, it could
find potential uses in biobleaching process in paper industries. 相似文献
5.
The high-molar mass from of β-glucosidase fromAspergillus niger strain NIAB280 was purified to homogeneity with a 46-fold increase in purification by a combination of ammonium sulfate precipitation,
hydrophobic interaction, ion-exchange and gel-filtration chromatography. The native and subunit molar mass was 330 and 110
kDa, respectively. The pH and temperature optima were 4.6–5.3 and 70°C, respectively. TheK
m andk
cat for 4-nitrophenyl β-d-glucopyranoside at 40°C and pH 5 were 1.11 mmol/L and 4000/min, respectively. The enzyme was activated by low and inhibited
by high concentrations of NaCl. Ammonium sulfate inhibited the enzyme. Thermolysin periodically inhibited and activated the
enzyme during the course of reaction and after 150 min of proteinase treatment only 10% activity was lost with concomitant
degradation of the enzyme into ten low-molar-mass active bands. When subjected to 0–9 mol/L transverse urea-gradient-PAGE
for 105 min at 12°C, the nonpurified β-glucosidase showed two major bands which denatured at 4 and 8 mol/L urea, respectively,
with half-lives of 73 min. 相似文献
6.
Two proteolytic thermophilic aerobic bacterial strains, PA-9 and PA-5, were isolated from Buranga hot springs in western Uganda.
The cells were rods, approximately 10–12 μm in length and 3 μm in width. Isolate PA-9 grew at between 38°C and 68°C (optimum,
62°C), and PA-5 grew at between 37°C and 72°C (optimum, 60°C). Both isolates grew optimally at pH 7.5–8.5. Their 16S rRNA
gene sequences indicated that they belong to the newly described genus Geobacillus. Zymogram analysis of the crude enzyme extracts revealed the presence of two extracellular proteases for isolate PA-5, and
at least eight for isolate PA-9. The optimum temperature and pH for casein-degrading activity were 70°C, pH 6.5 for isolate
PA-9, but caseinolytic activity could also be observed at 2°C. In the case of isolate PA-5, optimal activity was observed
over a temperature and pH range of 50–70°C and pH 5–10, respectively.
Received: 26 November 2001 / Accepted: 12 December 2001 相似文献
7.
Peixoto-Nogueira Sde C Michelin M Betini JH Jorge JA Terenzi HF Polizeli Mde L 《Journal of industrial microbiology & biotechnology》2009,36(1):149-155
The ability of xylanolytic enzymes produced by Aspergillus fumigatus RP04 and Aspergillus niveus RP05 to promote the biobleaching of cellulose pulp was investigated. Both fungi grew for 4–5 days in liquid medium at 40°C,
under static conditions. Xylanase production was tested using different carbon sources, including some types of xylans. A. fumigatus produced high levels of xylanase on agricultural residues (corncob or wheat bran), whereas A. niveus produced more xylanase on birchwood xylan. The optimum temperature of the xylanases from A. fumigatus and A. niveus was around 60–70°C. The enzymes were stable for 30 min at 60°C, maintaining 95–98% of the initial activity. After 1 h at
this temperature, the xylanase from A. niveus still retained 85% of initial activity, while the xylanase from A. fumigatus was only 40% active. The pH optimum of the xylanases was acidic (4.5–5.5). The pH stability for the xylanase from A. fumigatus was higher at pH 6.0–8.0, while the enzyme from A. niveus was more stable at pH 4.5–6.5. Crude enzymatic extracts were used to clarify cellulose pulp and the best result was obtained
with the A. niveus preparation, showing kappa efficiency around 39.6% as compared to only 11.7% for that of A. fumigatus. 相似文献
8.
N. I. Selin 《Russian Journal of Marine Biology》2010,36(1):26-33
In the summer of 2008, the abundance, local aggregation structure, growth rate, and life span of the gastropod Nucella freycineti inhabiting the littoral zone of Yankicha Island (Kuriles), which is affected by the postvolcanic activity of the Ushishir
Volcano were studied. The parameters varied within a wide range and appreciably depended on the distance mollusk populations
were from underwater and land gas-hydrothermal vents, which caused strong heating (up to 48°C) of cold sea waters and the
formation of an unusually acidic environment (pH approximately 3.5) in the Kraternaya Bay. The mollusks occurred at a water
temperature below 24°C and a pH above 4, but formed multiage populations at a temperature of 2–14°C and a pH of approximately
6.4–8.2. 相似文献
9.
β-Galactosidase was isolated from the cell-free extracts ofLactobacillus crispatus strain ATCC 33820 and the effects of temperature, pH, sugars and monovalent and divalent cations on the activity of the enzyme
were examined.L. crispatus produced the maximum amount of enzyme when grown in MRS medium containing galactose (as carbon source) at 37°C and pH 6.5
for 2 d, addition of glucose repressing enzyme production. Addition of lactose to the growth medium containing galactose inhibited
the enzyme synthesis. The enzyme was active between 20 and 60°C and in the pH range of 4–9. However, the optimum enzyme activity
was at 45°C and pH 6.5. The enzyme was stable up to 45°C when incubated at various temperatures for 15 min at pH 6.5. When
the enzyme was exposed to various pH values at 45°C for 1 h, it retained the original activity over the pH range of 6.0–7.0.
Presence of divalent cations, such as Fe2+ and Mn2+, in the reaction mixture increased enzyme activity, whereas Zn2+ was inhibitory. TheK
m was 1.16 mmol/L for 2-nitrophenyl-β-d-galactopyranose and 14.2 mmol/L for lactose. 相似文献
10.
Biochemical characterisation of the esterase activities of wine lactic acid bacteria 总被引:1,自引:0,他引:1
Esters are an important group of volatile compounds that can contribute to wine flavour. Wine lactic acid bacteria (LAB) have
been shown to produce esterases capable of hydrolysing ester substrates. This study aims to characterise the esterase activities
of nine LAB strains under important wine conditions, namely, acidic conditions, low temperature (to 10°C) and in the presence
of ethanol (2–18% v/v). Esterase substrate specificity was also examined using seven different ester substrates. The bacteria
were generally found to have a broad pH activity range, with the majority of strains showing maximum activity close to pH 6.0.
Exceptions included an Oenococcus oeni strain that retained most activity even down to a pH of 4.0. Most strains exhibited highest activity across the range 30–40°C.
Increasing ethanol concentration stimulated activity in some of the strains. In particular, O. oeni showed an increase in activity up to a maximum ethanol concentration of around 16%. Generally, strains were found to have
greater activity towards short-chained esters (C2–C8) compared to long-chained esters (C10–C18). Even though the optimal physicochemical
conditions for enzyme activity differed from those found in wine, these findings are of potential importance to oenology because
significant activities remained under wine-like conditions. 相似文献
11.
Valeria Calandrelli Agata Gambacorta Ida Romano Vito Carratore Licia Lama 《World journal of microbiology & biotechnology》2008,24(10):2269-2275
A novel thermo-alkali-stable catalase–peroxidase from Oceanobacillus oncorhynchi subsp. incaldaniensis subsp. nov., strain 20AG, was purified and characterized. The protein purified from the cells resulted in 110-fold purification
with a specific activity of 35,000 U/mg. The enzyme consisted of four identical subunits of 72 kDa as determined by SDS-PAGE
and the total molecular mass measured by gel filtration was 280 kDa. The heme content was determined to be 1 heme per homodimer.
The enzyme showed a Soret peak at 406 nm in the oxidized form and was easily reduced by dithionite. The enzyme showed an appreciable
peroxidase activity in addition to high catalase activity. The behaviour of this heme-enzyme was typical of the class of prokaryotic
catalase–peroxidases, which are sensitive to cyanide and insensitive to the eukaryotic catalase inhibitor 3-amino-1,2,4-triazole.
The enzyme was active over a temperature range from 30 to 60°C and a pH range from 5 to 10, with an optimum pH about 9.0 and
an optimum temperature of 40°C. The enzyme was stable in the pH range of 5.0 to 10.0 after 1 h of treatment at 40°C. The enzyme
was stable for 24 h at 40°C with a half-life of 4 h 60°C. The enzyme had a K
m of 24 mM for hydrogen peroxide. The amino terminal amino acid sequence of the catalase–peroxidase from strain 20AG was SEKRKMTTAFGA
and it showed no homology with other catalases. 相似文献
12.
The autolysis of yeast cells has practical implications in the production of fermented foods and beverages and flavourants
for food processing. Protein and RNA degradation during yeast autolysis are well described but the fate of DNA is unclear.
Yeast cells (Saccharomyces cerevisiae) were autolysed by incubating suspensions at 30–60°C (pH 7.0), and at pH 4.0–7.0 (40°C) for 10–14 days. Up to 55% of total
DNA was degraded, with consequent leakage into the extracellular environment of mainly 3′- and 5′-deoxyribonucleotides, and
lesser amounts of polynucleotides. The rate and extent of DNA degradation, composition of the DNA degradation products and
DNase activity were affected by temperature and pH. The highest amount of DNA degradation occurred at 40°C and pH 7.0, where
the highest DNase activity was recorded. DNase activity was lowest at 60°C and pH 4.0, where the proportion of polynucleotides
in the degradation products was higher.
Electronic Publication 相似文献
13.
Chai YY Rahman RN Illias RM Goh KM 《Journal of industrial microbiology & biotechnology》2012,39(5):731-741
Two genes that encode α-amylases from two Anoxybacillus species were cloned and expressed in Escherichia coli. The genes are 1,518 bp long and encode 506 amino acids. Both sequences are 98% similar but are distinct from other well-known
α-amylases. Both of the recombinant enzymes, ASKA and ADTA, were purified using an α-CD–Sepharose column. They exhibited an
optimum activity at 60°C and pH 8. Both amylases were stable at pH 6–10. At 60°C in the absence of Ca2+, negligible reduction in activity for up to 48 h was observed. The activity half-life at 65°C was 48 and 3 h for ASKA and
ADTA, respectively. In the presence of Ca2+ ions, both amylases were highly stable for at least 48 h and had less than a 10% decrease in activity at 70°C. Both enzymes
exhibited similar end-product profiles, and the predominant yield was maltose (69%) from starch hydrolysis. To the best of
our knowledge, most α-amylases that produce high levels of maltose are active at an acidic to neutral pH. This is the first
report of two thermostable, alkalitolerant recombinant α-amylases from Anoxybacillus that produce high levels of maltose and have an atypical protein sequence compared with known α-amylases. 相似文献
14.
Pathange Prakash Senigala K. Jayalakshmi Kuruba Sreeramulu 《Applied microbiology and biotechnology》2010,87(2):625-633
Two alkaline keratinases-I and II secreted by Bacillus halodurans PPKS-2 were purified and characterized. Both the keratinases were purified using ammonium sulfate, DEAE-Sephadex followed
by Sephadex G-200 column chromatography. The purification was 21.5-fold and 11.17% yield for keratinase-I and 23.7-fold with
yield 18.46 for keratinase-II and its molecular weights 30 and 66 kDa. Both purified enzymes were relatively stable over a
broad pH range 7.0–13.0 and optimally active at pH 11.0 and 60–70 °C. Keratinase-II was found to be more stable at 70 °C for
3 h and retained 100% of its activity, whereas keratinase-I lost 10% activity. Keratinase-I had high keratin disulfide reductase
activity with low keratinase activity whereas keratinase-II had high keratinase activity with low keratin disulfide reductase
activity. Keratinase activities of both the enzymes were completely inhibited by PMSF at 1 mM, whereas keratin disulfide reductase
activity of keratinase-I was not affected. Enzymes were active and stable in the presence of the surfactants, bleaching agents
(20% H2O2), commercial detergents (1%), and SDS (20%). Both the enzymes were partially sequenced and found that keratinase-I and II
had a homology with disulfide reductases and serine type of proteases, respectively. 相似文献
15.
Jianshe Wang Yingguo Bai Peilong Yang Pengjun Shi Huiying Luo Kun Meng Huoqing Huang Jun Yin Bin Yao 《World journal of microbiology & biotechnology》2010,26(5):917-924
A xylanase gene, xynE2, was cloned from thermoalkaline Anoxybacillus sp. E2 and was expressed in Escherichia coli BL21 (DE3). The gene consisted of 987 bp and encoded a 328-residue xylanase with a calculated molecular weight of 38.8 kDa.
On the basis of amino acid sequence similarities, this enzyme was assigned as a member of glycoside hydrolase family 10. Purified
recombinant XynE2 showed maximal activity at pH 7.8 and 65°C, and was thermostable at 60°C. The enzyme was highly active and
stable over a broad pH range, showing more than 90% of maximal activity at pH 6.6–pH 8.6 and retaining more than 80% of activity
at pH 4.6–pH 12.0, 37°C for 1 h, respectively. These favorable properties make XynE2 a good candidate in the pulp and paper
industries. This is the first report on gene cloning, expression and characterization of a xylanase from the genus Anoxybacillus. 相似文献
16.
Fernaud JR Marina A González K Vázquez J Falcón MA 《Applied microbiology and biotechnology》2006,70(2):212-221
Benzyl alcohol and starch-free commercial wheat bran were effective inducers of the laccase activity in cultures of Fusarium proliferatum (MUCL 31970). Initial pH value in the cultures was also an overriding factor for increasing its production. By gel permeation
high-performance liquid chromatography, the enzyme eluted as an apparently homogeneous peak with a molecular mass of 54 kDa,
but by isoelectrofocusing, two proteins with pI values of 5.17 and 5.07 were revealed. Two different phenoloxidase activities
were also detected after nondenaturing polyacrylamide gel electrophoresis. By matrix-assisted laser desorption/ionization–time
of flight–mass spectrometry (MALDI-TOF-MS), both proteins showed unique fingerprints, so they were classifiable as isozymes,
and were named laccase 1 (Lac1, pI 5.17) and laccase 2 (Lac2, pI 5.07). No clear matches were found when compared with other
proteins. The tandem mass spectrometry of some peptides from both isozymes reanalyzed by nanoelectron ionization–ion trap–mass
spectrometry (nESI-IT-MS) confirmed their unique character. The following interesting properties, particularly its stability
at alkaline pH, make this laccase a promising industrial enzyme for biotechnological applications: maximum activity at 60°C,
thermal stability for 2 h at 40°C, optimum pH 3.5 (km=62 μM) measured on 2,2′-azino-bis(3-ethylbenz-thiazoline-6-sulfonate),
and pH stability 4–8 (75% stability at pH levels 2.2 and 9) for 2 h at 25°C. 相似文献
17.
Investigation of the phenotypic properties of three mixotrophic bacteria, strains Sb-K, Sb-F, and Sb-S, isolated from an aboriginal
thermoacidophilic microbial community participating in biooxidation of ore with high antimony content (26%) and ore concentrates
from the Olympiadinskoe deposit under semicontinuous cultivation conditions at 46 ± 1°C, revealed the differentiating characteristics
of these strains. The isolated cultures grew lithotrophically through different numbers of transfers: strains Sb-F and Sb-K
grew through seven and eight transfers, respectively, and strain Sb-S grew through two or three transfers. Strains Sb-K and
Sb-S utilized a wide range of organic substrates for active organotrophic growth during nine or ten transfers, while strain
Sb-F was less tolerant to organic compounds. Strain Sb-K grew on a medium with the ore and sulfide ore concentrates in the
pH range of 1.0–3.0. Growth of strains Sb-F and Sb-S occurred in the pH ranges of 1.0–2.5 and 1.5–5.5 on media with Fe2+ and S0, respectively.. The optimal initial pH values of the media, corresponding to the maximum specific growth rates, were 1.6–1.7,
1.9, and 2.0–3.0 for strains Sb-K, Sb-F, and Sb-S, respectively. All three strains were able to grow within a broad temperature
range, 20–65°C, with an optimum at 46°C (Sb-K), 40–46°C (Sb-F), and 48–50°C (Sb-S). According to the results of DNA-DNA hybridization
and phylogenetic analysis, as well as their phenotypic characteristics, the isolates can be classified as novel strains of
species of the genus Sulfobacillus. Strains Sb-K, Sb-F, and Sb-S, isolated as predominant cultures on the media with sulfide compounds, iron, or sulfur, respectively,
were affiliated to the species S. thermotolerans, S. sibiricus, and S. thermosulfidooxidans. 相似文献
18.
A gene encoding an intracellular glucoamylase was identified in the genome of the extreme thermoacidophilic Archaeon Thermoplasma acidophilum. The gene taGA, consisting of 1,911 bp, was cloned and successfully expressed in Escherichia coli. The recombinant protein was purified 22-fold to homogeneity using heat treatment, anion-exchange chromatography, and gel
filtration. Detailed analysis shows that the glucoamylase, with a molecular weight of 66 kDa per subunit, is a homodimer in
its active state. Amylolytic activity was measured over a wide range of temperature (40–90°C) and pH (pH 3.5–7) and was maximal
at 75°C and at acidic condition (pH 5). The recombinant archaeal glucoamylase uses a variety of polysaccharides as substrate,
including glycogen and amylose. Maximal activity was measured towards amylopectin with a specific activity of 4.2 U/mg and
increased almost threefold in the presence of manganese. Calcium ions have a pronounced effect on enzyme stability; in the
presence of 5 mM CaCl2, the half-life increased from 15 min to 2 h at 80°C. 相似文献
19.
A marine fungus was isolated from the black tiger prawn Penaeus monodon at Nha Trang, Vietnam, on March 20, 2001 and named isolate NJM 0131. The fungus was identified as Haliphthoros milfordensis from the characteristics of asexual reproduction, and its physiological characteristics were investigated. Although the optimum
temperature for growth of the isolate was 25°–30°C, the fungus grew at a wide range of temperatures (15°–40°C). H. milfordensis grew well in 50%–100% seawater, but poorly in PYG agar containing 1.0%–5.0% NaCl and KCl. The fungus grew at a wide range
of pH (4.0–11.0) with the optimum pH value of 7.0–9.0. The isolate also showed pathogenicity to swimming crab larvae (Portunus trituberculatus) by artificial infection, but mortality was not high. This is the first report of disease in the black tiger prawn P. monodon in Vietnam caused by H. milfordensis.
Received: July 22, 2002 / Accepted: January 21, 2003
Correspondence to:K. Hatai 相似文献
20.
Carolina A. Lima José L. Lima Filho Benício B. Neto Attilio Converti Maria G. Carneiro da Cunha Ana L. F. Porto 《Biotechnology and Bioprocess Engineering》2011,16(3):549-560
A 24 full factorial design was used to identify the main effects and interactions of the initial medium pH, soybean flour concentration,
temperature and orbital agitation speed on extracellular collagenase production by Penicillium aurantiogriseum URM4622. The most significant variables for collagenase production were soybean flour concentration and initial medium pH
that had positive main effects, and temperature that had a negative one. Protein concentration in soybean flour revealed to
be a significant factor for the production of a collagenase serine proteinase. The most favorable production conditions were
found to be 0.75% soybean flour, pH 8.0, 200 rpm, and 28°C, which led to a collagenase activity of 164 U. The enzyme showed
an optimum activity at 37°C and pH 9.0, was stable over wide ranges of pH and temperature (6.0 ∼ 10.0 and 25 ∼ 45°C, respectively)
and was strongly inhibited by 10 mM phenylmethylsulphonylfluoride. The firstorder rate constants for collagenase inactivation
in the crude extract, calculated from semi-log plots of the residual activity versus time, were used in Arrhenius and Eyring
plots to estimate the main thermodynamic parameters of thermoinactivation (E*
d
= 107.4 kJ/mol and ΔH*
d
= 104.7 kJ/mol). The enzyme is probably an extracellular neutral serine collagenase effective on azocoll, gelatin and collagen
decomposition. 相似文献