共查询到20条相似文献,搜索用时 31 毫秒
1.
Lu L Zhao M Zhang BB Yu SY Bian XJ Wang W Wang Y 《Applied microbiology and biotechnology》2007,74(6):1232-1239
The white rot fungus Pycnoporus sanguineus produced high amount of laccase in the basal liquid medium without induction. Laccase was purified using ultrafiltration,
anion-exchange chromatography, and gel filtration. The molecular weight of the purified laccase was estimated as 61.4 kDa
by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme oxidized typical substrates of laccases including
2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonate), 2,6-dimethoxyphenol, and syringaldazine. The optimum pH and temperature for the purified
laccase were 3.0 and 65°C, respectively. The enzyme was stable up to 40°C, and high laccase activity was maintained at pH 2.0–5.0.
Sodium azide, l-cysteine, and dithiothreitol strongly inhibited the laccase activity. The purified enzyme efficiently decolorized Remazol
Brilliant Blue R in the absence of added redox mediators. The high production of P. sanguineus laccase as well as its decolorization ability demonstrated its potential applications in dye decolorization. 相似文献
2.
Evaluation of solid substrates for enzyme production by Coriolus versicolor, for use in bioremediation of chlorophenols in aqueous effluents 总被引:1,自引:0,他引:1
In the development of a system for the removal of chlorophenols from aqueous effluents, a range of solid substrates for the
growth of Coriolus versicolor were investigated. Substrates included wood chips, cereal grain, wheat husk and wheat bran. Suitability for transformation
of chlorophenols depended on laccase production by the fungus. The greatest amount of laccase (<25 Units g−1 substrate) was produced on wheat husk and wheat bran over 30 days colonisation. Aqueous extracts of laccase from wheat husk
and wheat bran cultures removed 100% of 2,4-dichlorophenol (50 ppm) from solution within 5 h and 75–80% of pentachlorophenol
(50 ppm) within 24 h. Wheat bran was formulated into pellets with biscuit flour to provide a compact substrate for fungal
immobilisation. Addition of 8–12% yeast extract to the pellets increased laccase production five-fold. Colonised pellets were
added to chlorophenol solutions in 200–4000-ml bioreactors, resulting in >90% removal of chlorophenols within 100 min.
Received: 10 April 2000 / Received revision: 4 July 2000 / Accepted: 10 July 2000 相似文献
3.
Gopinath V Meiswinkel TM Wendisch VF Nampoothiri KM 《Applied microbiology and biotechnology》2011,92(5):985-996
Corynebacterium glutamicum wild type lacks the ability to utilize the pentose fractions of lignocellulosic hydrolysates, but it is known that recombinants
expressing the araBAD operon and/or the xylA gene from Escherichia coli are able to grow with the pentoses xylose and arabinose as sole carbon sources. Recombinant pentose-utilizing strains derived
from C. glutamicum wild type or from the l-lysine-producing C. glutamicum strain DM1729 utilized arabinose and/or xylose when these were added as pure chemicals to glucose-based minimal medium or
when they were present in acid hydrolysates of rice straw or wheat bran. The recombinants grew to higher biomass concentrations
and produced more l-glutamate and l-lysine, respectively, than the empty vector control strains, which utilized the glucose fraction. Typically, arabinose and
xylose were co-utilized by the recombinant strains along with glucose either when acid rice straw and wheat bran hydrolysates
were used or when blends of pure arabinose, xylose, and glucose were used. With acid hydrolysates growth, amino acid production
and sugar consumption were delayed and slower as compared to media with blends of pure arabinose, xylose, and glucose. The
ethambutol-triggered production of up to 93 ± 4 mM l-glutamate by the wild type-derived pentose-utilizing recombinant and the production of up to 42 ± 2 mM l-lysine by the recombinant pentose-utilizing lysine producer on media containing acid rice straw or wheat bran hydrolysate
as carbon and energy source revealed that acid hydrolysates of agricultural waste materials may provide an alternative feedstock
for large-scale amino acid production. 相似文献
4.
K. M. J. Van Laere G. Beldman A. G. J. Voragen 《Applied microbiology and biotechnology》1997,47(3):231-235
An arabinofuranohydrolase (AXH-d3) was purified from a cell-free extract of Bifidobacterium adolescentis DSM 20083. The enzyme had a molecular mass of approximately 100 kDa as determined by gel filtration. It displayed maximum
activity at pH 6 and 30 °C. Using an arabinoxylan-derived oligosaccharide containing double-substituted xylopyranosyl residues
established that the enzyme specifically released terminal arabinofuranosyl residues linked to C-3 of double-substituted xylopyranosyl
residues. In addition, this arabinofuranohydrolase released arabinosyl groups from wheat flour arabinoxylan polymer but showed
no activity towards p-nitrophenyl α-l-arabinofuranoside or towards sugar-beet arabinan, soy arabinogalactan, arabino-oligosaccharides and arabinogalacto-oligosaccharides.
Received: 15 July 1996 / Received revision: 18 October 1996 / Accepted: 18 October 1996 相似文献
5.
Saayman M van Vuuren HJ van Zyl WH Viljoen-Bloom M 《Applied microbiology and biotechnology》2000,54(6):792-798
The dicarboxylic acid fumarate is an important intermediate in cellular processes and also serves as a precursor for the
commercial production of fine chemicals such as l-malate. Yeast species differ remarkably in their ability to degrade extracellular dicarboxylic acids and to utilise them
as their only source of carbon. In this study we have shown that the yeast Candida utilis effectively degraded extracellular fumarate and l-malate, but glucose or other assimilable carbon sources repressed the transport and degradation of these dicarboxylic acids.
The transport of both dicarboxylic acids was shown to be strongly inducible by either fumarate or l-malate while kinetic studies suggest that the two dicarboxylic acids are transported by the same transporter protein. In
contrast, Schizosaccharomyces pombe effectively degraded extracellular l-malate, but not fumarate, in the presence of glucose or other assimilable carbon sources. The Sch. pombe malate transporter was unable to transport fumarate, although fumarate inhibited the uptake of l-malate.
Received: 15 March 2000 / Received revision: 4 July 2000 / Accepted: 9 July 2000 相似文献
6.
Aspergillus tamarii produced extracellular xylanase and intracellular β-xylosidase inductively in washed glucose-grown mycelia incubated with
xylan and methyl β-d-xyloside, a synthetic glycoside. Methyl β-d-xyloside was a more effective inducer than xylan at the same concentration for both enzymes. Glucose and cycloheximide were
found to inhibit xylanase production by methyl β-d-xyloside. Methyl β-d-xyloside was hydrolyzed to xylose by mycelial extract in vitro.
Received: 23 May 1996 / Received revision: 5 September 1996 / Accepted: 13 October 1996 相似文献
7.
Novotný C Erbanová P Cajthaml T Rothschild N Dosoretz C Sasek V 《Applied microbiology and biotechnology》2000,54(6):850-853
Growth parameters, ligninolytic enzyme activities and ability to degrade polycyclic aromatic hydrocarbons by the fungus Irpex lacteus were characterized and compared with those of other white rot fungi capable of rapid decolorization of poly R-478 and Remazol
Brilliant Blue R dyes. I. lacteus was able to grow on mineral and complex media and efficiently colonized sterile and non-sterile soil by exploratory mycelium
growing from a wheat straw inoculum. In shallow stationary cultures growing on high nitrogen mineral medium containing 45 mM
ammonium as nitrogen source, the fungus produced lignin peroxidase (LIP), Mn-dependent peroxidase (MnP) and laccase simultaneously,
the respective maximal activities of 70, 970 and 36 U/l being attained around day 18. Growing in nitrogen-limited medium (2.4 mM
ammonium), no LIP was formed and levels of MnP and laccase decreased significantly. During growth in sterile soil, the fungus
synthesized LIP and laccase but not MnP. I. lacteus efficiently removed three- and four-ringed PAHs from liquid media and artificially spiked soil. The variety of ligninolytic
enzymes, robust growth, capability of soil colonization and resistance to inhibitory action of soil bacteria make I. lacteus a suitable fungal organism for use in bioremediation.
Received: 30 March 2000 / Accepted: 19 May 2000 相似文献
8.
The production of ligninolytic enzymes was studied in surface cultures of the South American white-rot fungus Nematoloma frowardii b19 and four other strains of this ecophysiological group (Clitocybula dusenii b11, Auricularia sp. m37a, wood isolates u39 and u45), which are able to depolymerize low-rank-coal-derived humic acids with the formation
of fulvic-acid-like compounds. The fungi produced the three crucial enzymes of lignin degradation – lignin peroxidase, manganese
peroxidase and laccase. In the case of N. frowardii b19, laccase and the two peroxidases could be stimulated by veratryl alcohol. Manganese (II) ions (Mn2+) caused a rapid increase of Mn peroxidase activity accompanied by the complete repression of lignin peroxidase. Under nitrogen-limited
conditions the growth as well as the production of ligninolytic enzymes was partly repressed. During the depolymerization
process of coal humic acids using solid agar media, gradients of ligninolytic enzyme activities toward 2,2′-azinobis(3-ethylbenzthiazoline-6-sulphonate)
and syringaldazine were detectable inside the agar medium.
Received: 5 August 1996 / Received revision: 13 November 1996 / Accepted: 15 November 1996 相似文献
9.
10.
T. Ohshiro M. Shinji Y. Morita Y. Takayama Y. Izumi 《Applied microbiology and biotechnology》1997,48(4):546-548
Microorganisms capable of cleaving the urethane bond of t-butoxycarbonyl (Boc) amino acids in a whole-cell reaction were screened among stock cultures, and Corynebacterium aquaticum IFO12154 was the most promising. The conversion of Boc-Ala to Ala was stimulated by CoSO4 in the medium and reaction mixture. The optimum whole-cell concentration was 25 mg lyophilized cells/ml. Boc-l-Met was the best substrate for this reaction, and other Boc-L-amino acids, as well as benzyloxycarbonyl-l-amino acids with hydrophobic residues, were also good substrates. Boc-d- and Z-d-amino acids were inert. When the reactions had proceeded for 24 h with each substrate at 10 mM, the molar conversion rates
from Boc-l-, dl- and d-Met were 100%, 50%, and 0% respectively. From 150 mM Boc-l-Met, 143 mM l-Met was formed at a molar yield of 95.3%.
Received: 3 September 1996 / Received last revision: 7 April 1997 / Accepted: 19 April 1997 相似文献
11.
Characteristics of dipeptide transport in pig jejunum in vitro 总被引:4,自引:0,他引:4
Winckler C Breves G Boll M Daniel H 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1999,169(7):495-500
Characteristics of dipeptide transport in pig jejunum were investigated in vitro by applying the Ussing-chamber technique
and mucosal uptake studies. Addition of both glycyl-l-glutamine and glycyl-l-sarcosine (20 mmol · l−1) to the mucosal buffer solution significantly increased the short-circuit current by 2.60 ± 0.15 and 1.57 ± 0.20 μeq · cm−2 · h−1, respectively. Concentration-dependent changes in short-circuit current followed Michaelis-Menten kinetics with similar affinity
constants for both dipeptides. From unidirectional flux rates for radiolabelled glycyl-l-sarcosine, a net flux rate for glycyl-l-sarcosine of 49.8 ± 6.7 nmol · cm−2 · h−1 was calculated. In mucosal uptake experiments, the apical influx of 14C-labelled glycyl-l-sarcosine into isolated porcine mucosa was pH dependent and significantly inhibited by glycyl-l-glutamine. Moreover, RT-PCR studies with primers derived from rabbit PepT1 identified two PCR fragments of identical size
to rabbit PepT1 from pig intestinal mRNA preparations. In conclusion, our studies revealed key features of mammalian intestinal
peptide transporters and give evidence for a PepT1-like transporter in the pig jejunum that could significantly contribute
to the overall amino acid absorption from the gut.
Accepted: 30 June 1999 相似文献
12.
H. De Wever S. De Cort I. Noots H. Verachtert 《Applied microbiology and biotechnology》1997,47(4):458-461
2-Hydroxybenzothiazole (OBT) is present in wastewaters from the industrial production of the rubber vulcanization accelerator
2-mercaptobenzothiazole (MBT). We have achieved the first isolation of axenic bacterial cultures capable of the degradation
of OBT and growth on this substrate as the sole source of carbon, nitrogen and energy. All isolates had similar characteristics
corresponding to one particular isolate, which was studied in more detail and identified as Rhodococcus rhodochrous. The strains were also capable of degrading benzothiazole (BT) but not MBT or benzothiazole-2-sulphonate (BTSO3). OBT was degraded at a concentration of up to 600 mg · l−1. BT was toxic above 300 mg · l−1. MBT inhibited OBT degradation. Growth on OBT was not significantly different at pH values of between 6.3 and 7.9 or salt
concentrations between 1 % and 3 %. In shake flasks the cells clumped together, which resulted in a lower rate of oxygen transfer
and slower degradation as compared to cells grown on OBT in a stirred reactor.
Received: 22 August 1996 / Received revision: 29 November 1996 / Accepted: 29 November 1996 相似文献
13.
Nawaz M. S. Zhang D. Khan A. A. Cerniglia C. E. 《Applied microbiology and biotechnology》1998,50(5):568-572
A gram-negative, rod-shaped bacterium capable of utilizing l-asparagine as its sole source of carbon and nitrogen was isolated from soil and identified as Enterobacter cloacae. An intracellularly expressed l-asparaginase was detected and it deaminated l-asparagine to aspartic acid and ammonia. High-pressure liquid chromatography analysis of a cell-free asparaginase reaction
mixture indicated that 2.8 mM l-asparagine was hydrolyzed to 2.2 and 2.8 mM aspartic acid and ammonia, respectively, within 20 min of incubation. High asparaginase
activity was found in cells cultured on l-fructose, d-galactose, saccharose, or maltose, and in cells cultured on l-asparagine as the sole nitrogen source. The pH and temperature optimum of l-asparaginase was 8.5 and 37–42 °C, respectively. The half-life of the enzyme at 30 °C and 37 °C was 10 and 8 h, respectively.
Received: 19 February 1998 / Received last revision: 4 June 1998 / Accepted: 10 July 1998 相似文献
14.
C. Felby B. R. Nielsen P. O. Olesen L. H. Skibsted 《Applied microbiology and biotechnology》1997,48(4):459-464
During laccase-catalyzed oxidation of beech wood fibers in an aqueous suspension, phenoxy radicals were detected in steady-state
concentrations by electron-spin resonance (ESR) spectrometry of the suspension liquid, suggesting that colloidal lignin functions
as a mediator between laccase and the fiber lignin matrix. Phenoxy radicals were observed directly, whereas ESR spin-trapping
techniques gave no evidence for reduced oxygen species, such as the superoxide or hydroxyl radical. A reaction mechanism involving
parallel direct oxidation of the lignin on fiber surfaces and a phenol/phenoxy cyclic mediator process in the suspension liquid
could accordingly describe laccase-catalyzed oxidation of beech wood fibers. Cytochrome c assays for detection of superoxide in systems involving lignin oxidized by oxidoreductases should be used with caution, as
cytochrome c may be reduced by species other than superoxide.
Received: 24 March 1997 / Received revision: 27 May 1997 / Accepted: 1 June 1997 相似文献
15.
High production of laccase by a new basidiomycete, <Emphasis Type="Italic">Trametes</Emphasis> sp 总被引:1,自引:0,他引:1
A new basidiomycete, Trametes sp. 420, produced laccase at 6,810 U l−1 (268 mg, 25.4 U mg−1 protein for guaiacol) in glucose medium and 7,870 U l−1 (310 mg) in cellobiose medium with induction by 0.5 mM Cu2+ and 6 mM o-toluidine. Laccase isozyme E (LacE) was the sole laccase in the fermentation products. It was stable at pH 5–9 and below
70°C over 30 min. The K
m values of LacE for four substrates (guaiacol ABTS, 2,6-dimethoxyphenol and syringaldazine) varied from 5 to 245 μM. The activity
of LacE was strongly inhibited by NaN3 but not by EDTA or dimethylsulfoxide. LacE at 0.5 U l−1 could decolorize industrial dyes. The open reading frame of the lacE gene was 2,130 bp and was interrupted by 10 introns. It displayed a high homology to laccases from other fungi.
Pingui Tong and Yuzhi Hong contributed equally to the study 相似文献
16.
Mahdi Mohammadian Mehrnoosh Fathi-Roudsari Nasrin Mollania Arastoo Badoei-Dalfard Khosro Khajeh 《Journal of industrial microbiology & biotechnology》2010,37(8):863-869
Laccases (benzenediol oxygen oxidoreductase; EC 1.10.3.2) have many biotechnological applications because of their oxidation
ability towards a wide range of phenolic compounds. Within recent years, researchers have been highly interested in the identification
and characterization of laccases from bacterial sources. In this study, we have isolated and cloned a gene encoding laccase
(CotA) from Bacillus sp. HR03 and then expressed it under microaerobic conditions and decreased temperature in order to obtain high amounts of
soluble protein. The laccase was purified and its biochemical properties were investigated using three common laccase substrates,
2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), syringaldazine (SGZ) and 2,6-dimethoxyphenol (2,6-DMP). K
M and k
cat were calculated 535 μM and 127 s−1 for ABTS, 53 μM and 3 s−1 for 2, 6-DMP and 5 μM and 20 s−1 for SGZ when the whole reactions were carried out at room temperature. Laccase activity was also studied when the enzyme
was preincubated at 70 and 80°C. With SGZ as the substrate, the activity was increased three-fold after 50 min preincubation
at 70°C and 2.4-fold after 10 min preincubation at 80°C. Preincubation of the enzyme in 70°C for 30 min raised the activity
four-fold with ABTS as the substrate. Also, l-dopa was used as a substrate. The enzyme was able to oxidize l-dopa with the K
M and k
cat of 1,493 μM and 194 s−1, respectively. 相似文献
17.
Cloning and characterization of a new laccase from Bacillus licheniformis catalyzing dimerization of phenolic acids 总被引:1,自引:0,他引:1
Koschorreck K Richter SM Ene AB Roduner E Schmid RD Urlacher VB 《Applied microbiology and biotechnology》2008,79(2):217-224
A new laccase gene (cotA) was cloned from Bacillus licheniformis and expressed in Escherichia coli. The recombinant protein CotA was purified and showed spectroscopic properties, typical for blue multi-copper oxidases. The
enzyme has a molecular weight of ~65 kDa and demonstrates activity towards canonical laccase substrates 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic
acid) (ABTS), syringaldazine (SGZ) and 2,6-dimethoxyphenol (2,6-DMP). Kinetic constants K
M and k
cat for ABTS were of 6.5 ± 0.2 μM and 83 s−1, for SGZ of 4.3 ± 0.2 μM and 100 s−1, and for 2,6-DMP of 56.7 ± 1.0 μM and 28 s−1. Highest oxidizing activity towards ABTS was obtained at 85°C. However, after 1 h incubation of CotA at 70°C and 80°C, a
residual activity of 43% and 8%, respectively, was measured. Furthermore, oxidation of several phenolic acids and one non-phenolic
acid by CotA was investigated. CotA failed to oxidize coumaric acid, cinnamic acid, and vanillic acid, while syringic acid
was oxidized to 2,6-dimethoxy-1,4-benzoquinone. Additionally, dimerization of sinapic acid, caffeic acid, and ferulic acid
by CotA was observed, and highest activity of CotA was found towards sinapic acid. 相似文献
18.
Ophiostoma ulmi and O. novo-ulmi, both causative agents of Dutch elm disease, can be differentiated by their potential to produce constitutive extracellular
laccase. The enzyme has been purified from the culture filtrate to apparent electrophoretic homogeneity and has been partially
characterized. The laccase was glycosylated and found to have a molecular mass of 79 kDa or 70 kDa by SDS-PAGE and gel filtration,
respectively. The pI, determined by chromatofocusing, was 5.1. Syringaldazine, guaiacol, and other typical laccase substrates
were oxidized. No oxidation of tyrosine was detected. NaN3 (0.01%) completely abolished the activity towards 2,6-dimethoxyphenol.
Received: 31 March 1997 / Accepted: 9 May 1997 相似文献
19.
An extracellular enzyme with glucose dehydrogenase activity was purified from liquid cultures of the basidiomycete Agaricus bisporus after growth with d-cellobiose or d-glucose as carbon source. The molecular mass was measured as 57 kDa by gel filtration and 55 kDa by sodiumdodecyl sulphate/polyacrylamide
gel electrophoresis, while the isoelectric point was at pH 3.6. By analysis of 1H-NMR spectra in D2O, the product of d-glucose oxidation was identified as 3-ketoglucose. The substrates oxidized included d-cellobiose, l-arabinose, d-xylose and sucrose, but the specificity parameter (k
cat/K
m) was highest for d-glucose. Two electron acceptors were identified, namely 2,6-dichloroindophenol and p-benzoquinone, but reduction of dioxygen, ferricyanide or cytochrome c was not detectable. The selective C-3 oxidation of d-glucose is well-characterized for Agrobacterium and Flavobacterium, but this is the first report for a fungus.
Received: 19 June 1998 / Received revision: 15 September 1998 / Accepted: 17 September 1998 相似文献
20.
Muñoz AJ Hernández-Chávez G de Anda R Martínez A Bolívar F Gosset G 《Journal of industrial microbiology & biotechnology》2011,38(11):1845-1852
l-3,4-dihydroxyphenylalanine (l-DOPA) is an aromatic compound employed for the treatment of Parkinson's disease. Metabolic engineering was applied to generate
Escherichia coli strains for the production of l-DOPA from glucose by modifying the phosphoenolpyruvate:sugar phosphotransferase system (PTS) and aromatic biosynthetic pathways.
Carbon flow was directed to the biosynthesis of l-tyrosine (l-Tyr), an l-DOPA precursor, by transforming strains with compatible plasmids carrying genes encoding a feedback-inhibition resistant
version of 3-deoxy-d-arabino-heptulosonate-7-phosphate synthase, transketolase, the chorismate mutase domain from chorismate mutase-prephenate dehydratase
from E. coli and cyclohexadienyl dehydrogenase from Zymomonas mobilis. The effects on l-Tyr production of PTS inactivation (PTS− gluc+ phenotype), as well as inactivation of the regulatory protein TyrR, were evaluated. PTS inactivation caused a threefold increase
in the specific rate of l-Tyr production (q
l-Tyr), whereas inactivation of TyrR caused 1.7- and 1.9-fold increases in q
l-Tyr in the PTS+ and the PTS− gluc+ strains, respectively. An 8.6-fold increase in l-Tyr yield from glucose was observed in the PTS− gluc+
tyrR
− strain. Expression of hpaBC genes encoding the enzyme 4-hydroxyphenylacetate 3-hydroxylase from E. coli W in the strains modified for l-Tyr production caused the synthesis of l-DOPA. One of such strains, having the PTS− gluc+
tyrR
− phenotype, displayed the best production parameters in minimal medium, with a specific rate of l-DOPA production of 13.6 mg/g/h, l-DOPA yield from glucose of 51.7 mg/g and a final l-DOPA titer of 320 mg/l. In a batch fermentor culture in rich medium this strain produced 1.51 g/l of l-DOPA in 50 h. 相似文献