| 1. |
- Bennett, Neil A., et al.
(författare)
-
Biochemical and catalytic properties of an endoxylanase purified from the culture filtrate of Thermomyces lanuginosus ATCC 46882
- 1998
-
Ingår i: Carbohydrate Research. - 0008-6215 .- 1873-426X. ; 306:3, s. 445-455
-
Tidskriftsartikel (refereegranskat)abstract
- An endoxylanase (1,4-beta-D-xylan xylanohydrolase, EC 3.2.1.8) from the culture filtrates of T. lanuginosus ATCC 46882 was purified to homogeneity by DEAE-Sepharose and Bio-Gel P-30 column chromatographies. The purified endoxylanase had a specific activity of 888.8 mumol min-1 mg-1 protein and accounted for approximately 30% of the total protein secreted by this fungus. The molecular mass of native (non-denatured) and denatured endoxylanase were 26.3 and 25.7 kD as, respectively. Endoxylanase had a pI of 3.7 and was optimally active between pH 6.0-6.5 and at 75 degrees C. The enzyme showed > 50% of its original activity between pH 5.5-9.0 and at 85 degrees C. The pH and temperature stability studies revealed that this endoxylanase was almost completely stable between pH 5.0-9.0 and up to 60 degrees C for 5 h and at pH 10.0 up to 55 degrees C for 5 h. Thin-layer chromatography (TLC) analysis showed that endoxylanase released mainly xylose (Xyl) and xylobiose (Xyl2) from beechwood 4-O-methyl-D-glucuronoxylan, O-acetyl-4-O-methyl-D-glucuronoxylan and rhodymenan (a beta-(1-->3)-beta(1-->4)-xylan). Also, the enzyme released an acidic xylo-oligosaccharide from 4-O-methyl-D-glucuronoxylan, and an isomeric xylotetraose and an isomeric xylopentaose from rhodymenan. The enzyme hydrolysed [1-3H]-xylo-oligosaccharides in an endofashion, but the hydrolysis of [1-3H]-xylotriose appeared to proceed via transglycosylation. since the xylobiose was the predominant product. Endoxylanase was not active on pNPX and pNPC at 40 and 100 mM for up to 6 h, but showed some activity toward pNPX at 100 mM after 20-24 h. The results suggested that the endoxylanase from T. lanuginosus belongs to family 11.
|
|
| 2. |
- Caridis, Konstantina-Anna, et al.
(författare)
-
Simultaneous production of glucose oxidase and catalase by Alternaria alternata
- 1991
-
Ingår i: Applied Microbiology and Biotechnology. - 0175-7598 .- 1432-0614. ; 34:6, s. 794-797
-
Tidskriftsartikel (refereegranskat)abstract
- A number of factors affecting simultaneous production of cell-bound glucose oxidase and catalase by the fungus Alternaria alternata have been investigated. Consecutive optimization of the type and concentration of nitrogen and carbon source, the initial pH and growth temperature resulted in a simultaneous increase in glucose oxidase and catalase by 780% and 68% respectively. Two second-order equations, describing the combined effect of pH and temperature on the activity of each enzyme, revealed that glucose oxidase had its optima at pH 7.9 and 32.3°C and catalase at pH 8.5 and 18.1°C. Under certain growth conditions, yields as high as 23.5 and 18,100 units/g carbon source for glucose oxidase and catalase, respectively, were simultaneously obtained.
|
|
| 3. |
- Christakopoulos, Paul, et al.
(författare)
-
Direct conversion of sorghum carbohydrates to ethanol by a mixed microbial culture
- 1993
-
Ingår i: Bioresource Technology. - 0960-8524 .- 1873-2976. ; 45:2, s. 89-92
-
Tidskriftsartikel (refereegranskat)abstract
- The carbohydrates of sweet sorghum were directly converted to ethanol by a mixed culture of Fusarium oxysporum F3 and Saccharomyces cerevisiae 2541. A number of factors affecting this bioconversion was studied. Optimum ethanol yields of 33·2 g/100 g of total sorghum carbohydrates, corresponding to 10·3 g/100 g of fresh stalks, were obtained. These values represented 68·6% of the theoretical yield based on total polysaccharides and exceeded that based on oligosaccharides of sorghum by 53·7%. The results demonstrated that more than half of the sorghum polysaccharides were directly fermented to ethanol, thus making the process worthy of further investigation.
|
|
| 4. |
- Christakopoulos, Paul, et al.
(författare)
-
Enhancement of pH-stability of a low molecular mass endoglucanase from Fusarium oxysporum by protein pegylation
- 1998
-
Ingår i: Carbohydrate Research. - 0008-6215 .- 1873-426X. ; 314:1-2, s. 95-99
-
Tidskriftsartikel (refereegranskat)abstract
- The stability of the low molecular mass endoglucanase (23.2 kDa) from Fusarium oxysporum at alkaline pH was enhanced by chemical modification. Two distinct types of amino acid-specific modifiers were used. The first, either cyanuric chloride activated polyethylene glycol (CC–PEG) or polyethylene glycol succinimidyl succinate active ester (SS–PEG), react (more or less specifically) with protein amino groups. The second type, maleimide polyethylene glycol (Mal–PEG), is specific for cysteinyl residues. The enzyme lost almost all of its activity when modified with CC–PEG, whereas no inactivation was observed with SS–PEG and Mal–PEG. The modified endoglucanase showed remarkably enhanced alkaline pH stability. When acting upon cello-oligosaccharides and 4-methylumbelliferyl cello-oligosaccharides, the enzyme preferentially cleaved the internal glycosidic bonds. The modified enzymes mediated a decrease in the viscosity of carboxymethyl cellulose (CMC) associated with the release of only small amounts of reducing sugar. Thus, the modified enzyme retains the endo character of the native enzyme
|
|
| 5. |
- Christakopoulos, Paul, et al.
(författare)
-
Optimization of β-glucosidase catalysed synthesis of trisaccharides from cellobiose and gentiobiose
- 1994
-
Ingår i: Biotechnology letters. - 0141-5492 .- 1573-6776. ; 16:6, s. 587-592
-
Tidskriftsartikel (refereegranskat)abstract
- Purified β-Glucosidase from Fusarium oxysporum catalysed the hydrolysis and transglycosylation reactions in the presence of cellobiose and gentiobiose. The product of the latter reaction was mainly a triose. The time of incubation, pH and substrate concentration for transglycosylation reaction were optimised. Under optimal conditions, the concentration of glucose and triose reached approximately 15–20 % of the initial substrate concentration. These results suggested that β-glucosidase from F.oxysporum is an ideal enzyme for the synthesis of triose in reasonable quantities.
|
|
| 6. |
- Christakopoulos, Paul, et al.
(författare)
-
Production and characterization of extracellular lipase from Calvatia gigantea
- 1992
-
Ingår i: Applied Microbiology and Biotechnology. - 0175-7598 .- 1432-0614. ; 38:2, s. 194-197
-
Tidskriftsartikel (refereegranskat)abstract
- A number of factors affecting production of extracellular lipase by the edible fungus Calvatia gigantea were investigated. Consecutive optimization of carbon and nitrogen sources, initial pH of culture medium and growth temperature resulted in an increase in lipase activity of 87%. Under optimum conditions, activities as high as 22.4 units ml−1 of culture medium were obtained, competing favourably with most activities reported for other lipase hyperproducing microorganisms. The enzyme was optimally active at pH 7.0 and 30°C and had, at optimum pH, half-lives of 75.7 and 22.9 min at 45 and 55°C. Both high activity and kinetic characteristics of the enzyme make this process worthy of further investigation.
|
|
| 7. |
- Christakopoulos, Paul, et al.
(författare)
-
Purification and characterisation of a major xylanase with cellulase and transferase activities from Fusarium oxysporum
- 1996
-
Ingår i: Carbohydrate Research. - : Elsevier BV. - 0008-6215 .- 1873-426X. ; 289, s. 91-104
-
Tidskriftsartikel (refereegranskat)abstract
- A major xylanase from Fusarium oxysporum was purified to homogeneity by gel filtration, affinity, and ion-exchange chromatographies. It has a molecular mass of 60.2 kDa and pl of 6.6 and was optimally active at pH 7.4 and at 50 °C. The enzyme was stable over the pH range 5.8–8.2 at 40 °C for 24 h and lost 45% of its original activity at pH 9.0 under the identical conditions. The enzyme rapidly hydrolysed xylans from oat spelts (husks) and birchwood, but the activities on carboxymethylcellulose (CMC), filter paper, and Avicel were very low. Determination of kcat/Km revealed that the enzyme hydrolysed oat spelts and birchwood xylans, 15–30 times more efficiently than CMC. In a 24 h incubation, at pH 7.0 and 9.0, the enzyme hydrolysed oat spelts and birchwood xylans by 75 and 65%, respectively. However, at pH 7.0, the enzyme released almost equal amounts of xylose and xylobiose from both xylans, whereas at pH 9.0, the concentration of xylobiose was twice as muchi as that of xylose and xylotriose. Xylanase attacked preferentially the internal glycosidic bonds of xylo- and 4-methylumbelliferyl cello-oligosaccharides [MeUmb(Glc)n]. The enzyme catalysed transglycosylation reaction with xylotriose, xylotetraose, and xylopentaose as donors and 4-methylumbelliferyl β-d-glucoside (MeUmbGlc) as an acceptor.
|
|
| 8. |
- Christakopoulos, Paul, et al.
(författare)
-
Purification and Characterisation of an Extracellular β-Glucosidase with Transglycosylation and Exo-glucosidase Activities from Fusarium oxysporum
- 1994
-
Ingår i: European Journal of Biochemistry. - : Wiley. - 0014-2956 .- 1432-1033. ; 224:2, s. 379-385
-
Tidskriftsartikel (refereegranskat)abstract
- An extracellular β-glucosidase from Fusarium oxysporum was purified to homogeneity by gel-filtration and ion-exchange chromatographies. The enzyme, a monomeric protein of 110 kDa, was maximally active at pH 5.0–6.0 and at 60°C. It hydrolysed 1→4-linked aryl-β-glucosides and 1→4-linked, 1→3-linked and 1→6–linked β-glucosides. The apparent Km and kcat values for p -nitrophenyl β-d-glucopyranoside (4-NpGlcp) and cellobiose were 0.093 (Km), 1.07 mM (kcat) and 1802 (Km), 461.5 min-1 (kcat), respectively. Glucose and gluconolactone inhibited the enzyme competitively with Ki values of 2.05 mM and 3.03 μM, respectively. Alcohols activated the enzyme; butanol showed maximum effect (2.2-fold at 0.5 M) while methanol increased the activity by 1.4-fold at 1 M. The enzyme catalysed the synthesis of methylglucosides, ethylglucoside and propylglucosides, as well as trisaccharides in the presence of different alcohols and disaccharides, respectively. In addition, the enzyme hydrolysed the unsubstituted and methylumbelliferyl cello-oligosaccharides [MeUmb(Glc)n] but the rate of hydrolysis decreased with increasing chain length. Analysis of products released from MeUmb(Glc)n as a function of time revealed that the enzyme attacked these substrates in a stepwise manner and from both ends. Thus, β-glucosidase from F. oxysporum, with the above interesting properties, could be of commercial interest.
|
|
| 9. |
- Christakopoulos, Paul, et al.
(författare)
-
Purification and mode of action of an alkali-resistant endo-1,4-β-glucanase from Bacillus pumilus
- 1999
-
Ingår i: Archives of Biochemistry and Biophysics. - : Elsevier BV. - 0003-9861 .- 1096-0384. ; 364:1, s. 61-66
-
Tidskriftsartikel (refereegranskat)abstract
- Alkaline endo-1,4-β-d-glucanase was secreted byBacillus pumilusgrown in submerged culture on a combination of oat spelt xylan and corn starch as carbon sources. The enzyme was purified to homogeneity by Sephacryl S-200 and Q-Sepharose column chromatography. The protein corresponded to molecular mass and pIvalues of 67 kDa and 3.7, respectively. The enzyme was optimally active at pH 7.0–8.0 and 60°C and retained 50% of its optimum activity at pH 12. The most notable characteristic of the endoglucanase was its high stability up to pH 12 for 20 h at 30°C. The enzyme hydrolyzed carboxymethylcellulose (CMC) and cello-oligosaccharides but was inactive on cellobiose, cellotriose, Avicel, xylan, 4-nitrophenyl-β-d-glucoside, 4-nitrophenyl-β-d-cellobioside, and 4-nitrophenyl-β-d-xyloside. Analysis of reaction mixtures by HPLC revealed that the enzyme produced almost exclusively cellotriose when acted on CMC and appeared to hydrolyze cello-oligosaccharides by successively releasing cellotriose. The use of 4-methylumbelliferyl cello-oligosaccharides and the determination of bond cleavage frequency revealed that the enzyme preferentially hydrolyzed the third glycosidic bond adjacent to the glycon. The enzyme mediated a decrease in the viscosity of CMC associated with a release of only small amounts of reducing sugar. The enzyme activity was not inhibited by metal ions, surfactants, and chelating agents used as components of laundry detergents.
|
|
| 10. |
|
|
| 11. |
|
|
| 12. |
- Katapodis, Petros, et al.
(författare)
-
Biochemical and catalytic properties of an endoxylanase purified from the culture filtrate of Sporotrichum thermophile
- 2003
-
Ingår i: Carbohydrate Research. - 0008-6215 .- 1873-426X. ; 338:18, s. 1881-1890
-
Tidskriftsartikel (refereegranskat)abstract
- An endo-β-1,4-xylanase (1,4-β-d-xylan xylanoxydrolase, EC 3.2.1.8) present in culture filtrates of Sporotrichum thermophile ATCC 34628 was purified to homogeneity by Q-Sepharose and Sephacryl S-200 column chromatographies. The enzyme has a molecular mass of 25,000 Da, an isoelectric point of 6.7, and is optimally active at pH 5 and at 70 °C. Thin-layer chromatography (TLC) analysis showed that endo-xylanase liberates mainly xylose (Xyl) and xylobiose (Xyl2) from beechwood 4-O-methyl-d-glucuronoxylan, O-acetyl-4-O-methylglucuronoxylan and rhodymenan (a β-(1→4)-β(1→3)-xylan). Also, the enzyme releases an acidic xylo-oligosaccharide from 4-O-methyl-d-glucuronoxylan, and an isomeric xylotetraose and an isomeric xylopentaose from rhodymenan. Analysis of reaction mixtures by high performance liquid chromatography (HPLC) revealed that the enzyme cleaves preferentially the internal glycosidic bonds of xylooligosaccharides, [1-3H]-xylooligosaccharides and xylan. The enzyme also hydrolyses the 4-methylumbelliferyl glycosides of β-xylobiose and β-xylotriose at the second glycosidic bond adjacent to the aglycon. The endoxylanase is not active on pNPX and pNPC. The enzyme mediates a decrease in the viscosity of xylan associated with a release of only small amounts of reducing sugar. The enzyme is irreversibly inhibited by series of ω-epoxyalkyl glycosides of d-xylopyranose. The results suggest that the endoxylanase from S. thermophile has catalytic properties similar to the enzymes belonging to family 11.
|
|
| 13. |
- Katapodis, Petros, et al.
(författare)
-
Enzymic production of a feruloylated oligosaccharide with antioxidant activity from wheat flour arabinoxylan
- 2003
-
Ingår i: European Journal of Nutrition. - : Springer Science and Business Media LLC. - 1436-6207 .- 1436-6215. ; 42:1, s. 55-60
-
Tidskriftsartikel (refereegranskat)abstract
- Background Main cereals such as rice, wheat, barley, and corn belong to the family Gramineae and have similar cell-wall composition. Since cereal cell walls are a good source of dietary fibre, meeting one-half of the daily requirement of 30 g of dietary fibre can be achieved by the regular consumption of cereals. Many studies have dealt with the isolation of feruloylated oligosaccharides from Gramineae by treatment with polysaccharide hydrolysing enzymes. Aim of this study Therefore, the purpose of this study was to investigate the production of feruloylated oligosaccharides from insoluble wheat flour arabinoxylan (WFAX) by treatment with a Thermoascus aurantiacus family 10 endoxylanase (XYLI) and the evaluation of their antioxidant activity. Methods The main feruloylated oligosaccharide was purified by anion-exchange and size-exclusion chromatography (SEC). Alkaline saponification and acid hydrolysis were used for product identification. Evaluation of antioxidant activity was performed by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) reduction assay and the inhibition of copper-mediated oxidation of low density lipoprotein (LDL). Results The optimal conditions for WFAX hydrolysis using the XYLI have been determined to be 100 U g(-1) of WFAX for 30 min at 50 degreesC. Saponification of the oligosaccharide released FA and oligosaccharide. The released oligosaccharide consisted of arabinose and xylose in a molar ratio of 1:3 and these results support the identity of the feruloylated oligosaccharide as feruloyl arabinoxylotrisaccharide (FAX(3)). FAX(3) showed profound antioxidant activity in 2,2-diphenyl-1-picrylhydrazyl (DPPH) reduction assay exhibiting an antiradical efficiency of 0.035 (x 10(-3)) and inhibited the copper-mediated oxidation of human low density lipoprotein (LDL) in a dose-dependent manner with almost complete inhibition at 32 muM. Conclusion A feruloylated oligosaccharide (FAX(3)) was isolated from WFAX after enzymatic treatment with XYLI. We verified antioxidant activity of FAX(3) which may be important in preventing or reducing the progression of atherosclerosis by inhibiting the peroxidation of lipoproteins.
|
|
| 14. |
- Katapodis, Petros, et al.
(författare)
-
Enzymic production of aldopentauronic acid and use as bioregulator in plant airlift bioreactors
- 2003
-
Ingår i: Journal of Bioscience and Bioengineering. - 1389-1723 .- 1347-4421. ; 95:6, s. 630-632
-
Tidskriftsartikel (refereegranskat)abstract
- Neutral and acidic oligosaccharides were obtained from birchwood xylan by treatment with an endoxylanase, family 11 class, from Sporotrichum thermophile. The main acidic xylooligosaccharide (aldopentauronic acid) was separated from the hydrolysate by anion-exchange and size-exclusion chromatography and the structure was determined by 13C NMR spectroscopy. The aldopentauronic acid yield was 25% (w/w) of the total solubilized sugars. The addition of purified aldopentauronic acid at a concentration of 5 mg/l to cucumber liquid culture in 2.5-l airlift bioreactors caused in increase in both the number of regenerants and their fresh weight.
|
|
| 15. |
- Katapodis, Petros, et al.
(författare)
-
Production of β-Fructofuranosidase from Sporotrichum thermophile and Its Application in the Synthesis of Fructooligosaccharides
- 2003
-
Ingår i: Food biotechnology. - 0890-5436 .- 1532-4249. ; 17:1, s. 1-14
-
Tidskriftsartikel (refereegranskat)abstract
- Production of β-fructofuranosidase from the thermophilic fungus Sporotrichum thermophile was studied. The effect of nitrogen source, as well as the type and concentration of carbon source on enzyme production was examined. The results from flask experiments were used for the production of the enzyme in 7-l bioreactors. β-Fructofuranosidase from Sporotrichum thermophile showed both transfructosylating and hydrolytic activities. It was optimally active at 60°C, while the optimal pHs for hydrolysis and transfructosylation were 4.0 and 6.0, respectively. Synthesis of fructooligosaccharides was maximized at 20% (w/v) initial sucrose concentration. The major sugar produced by the transfructosylating activity of the enzyme was 6-kestose
|
|
| 16. |
|
|
| 17. |
- Mamma, Diomi, et al.
(författare)
-
Biochemical characterization of the multi-enzyme system produced by Penicillium decumbens grown on rutin
- 2004
-
Ingår i: Food biotechnology. - 0890-5436 .- 1532-4249. ; 18:1, s. 1-18
-
Tidskriftsartikel (refereegranskat)abstract
- Penicillium decumbens produced a set of enzymes, including a monoxygenase and two glycosidases, which degrade rutin, a nontoxic flavonoid glycoside, to water-soluble products. The monoxygenase (quercetinase) cleaves the heterocyclic ring in quercetin, the aglycone part of rutin. The glycosidases (alpha-L-rhamnosidase and beta-glucosidase) hydrolyze the bonds between quercetin and rutinose, and between glucose and rhamnose, the constituent monosaccharides of rutinose. Simultaneous production of the three enzymes was optimized following the examination of a number of culture conditions. Maximum enzyme activities were observed when the fungus was grown at 30 °C with an initial pH of 7.0, using 8.0 g/L rutin and 9.0 g/L di-ammonium hydrogen phosphate as carbon and nitrogen sources, respectively. The enzymes were purified to electrophoretic homogeneity by a series of consecutive chromatographic steps including anion and cation exchange as well as gel filtration. The purified quercetinase revealed an apparent tetrameric structure, with a reduced molecular mass of 45 kDa. alpha-L-Rhamnosidase showed an apparent molecular mass of 58 kDa and the purified beta-glucosidase was a tetramer exhibiting a reduced molecular mass of 120 kDa.
|
|
| 18. |
- Panagiotou, Gianni, et al.
(författare)
-
Induction, purification, and characterization of two extracellular alpha-L-arabinofuranosidases from Fusarium oxysporum
- 2003
-
Ingår i: Canadian journal of microbiology (Print). - 0008-4166 .- 1480-3275. ; 49:10, s. 639-644
-
Tidskriftsartikel (refereegranskat)abstract
- In the presence of L-arabinose as sole carbon source, Fusarium oxysporum produces two α-L-arabinofuranosidases (ABFs) named ABF1 and ABF2, with molecular masses of 200 and 180 kDa, respectively. The two F. oxysporum proteins have been purified to homogeneity. The purified enzymes are composed of three equal subunits and are neutral proteins with pIs of 6.0 and 7.3 for ABF1 and ABF2, respectively. With p-nitrophenyl α-L-arabinofuranoside (pNPA) as the substrate, ABF1 and ABF2 exhibited Km values of 0.39 and 0.28 mmol·L–1, respectively, and Vmax values of 1.6 and 4.6 µmol·min–1·(mg of protein)–1, respectively, and displayed optimal activity at pH 6.0 and 50–60 °C. ABFs released arabinose only from sugar beet arabinan and not from wheat soluble and insoluble arabinoxylans. The enzymes were not active on substrates containing ferulic acid ester linked to C-5 and C-2 linkages of pNPA showing that phenolic substituents of pNPA sterically hindered the action of ABFs.Key words: α-L-arabinofuranosidase, enzyme purification, enzyme induction.
|
|
| 19. |
- Panagiotou, Gianni, et al.
(författare)
-
Production of cellulolytic and xylanolytic enzymes by Fusarium oxysporum grown on corn stover in solid state fermentation
- 2003
-
Ingår i: Industrial crops and products (Print). - 0926-6690 .- 1872-633X. ; 18:1, s. 35-47
-
Tidskriftsartikel (refereegranskat)abstract
- Corn stover is an abundant, potential fermentation substrate. Production of cellulolytic and xylanolytic enzymes by the mesophilic fungus Fusarium oxysporum under solid state culture (SSC) on corn stover was enhanced by optimization of the type of nitrogen source, initial moisture level, growth temperature and initial pH of the culture medium. Under these conditions, yields as high as 304, 4.1, 0.140, 1840 and 0.041 U/g of carbon source of endoglucanase, cellobiohydrolase, β-glucosidase, xylanase and β-xylosidase, respectively, were obtained. SCC in a laboratory horizontal bioreactor using the optimized medium allowed the large scale production of the multienzymic system in similar yields. Chromogenic (fluorogenic) 4-methylumbelliferyl β-glycosides of cellobiose and xylobiose were used to characterize the major activities of the multienzyme component, after separation by isoelectric focusing (IEF) electrophoresis. The zymograms indicated one major cellulase and four xylanase activities exhibiting pI values 5 and 5, 6, 7.3, 8.3, respectively.
|
|
| 20. |
- Papaparaskevas, Dimitris, et al.
(författare)
-
Optimizing production of extracellular lipase from Rhodotorula glutinis
- 1992
-
Ingår i: Biotechnology letters. - 0141-5492 .- 1573-6776. ; 14:5, s. 397-402
-
Tidskriftsartikel (refereegranskat)abstract
- Production of extracellular lipase byRhodotorula glutinis was substantially enhanced when the type and concentration of carbon and nitrogen source, the initial pH of culture medium and the growth temperature were consecutively optimized. Lipase activity as high as 30.4 U/ml of culture medium was obtained at optimum conditions, comparing favourably with most of the activities reported for other lipase hyperproducing microorganisms. The enzyme was optimally active at pH 7.5 and 35°C and had, at optimum pH, half-lives of 45 and 11.8 min at 45 and 55°C respectively. The high activity and kinetic characteristics of the enzyme make this process worthy of further investigation.
|
|
| 21. |
- Puchart, Vladimı́r, et al.
(författare)
-
Production of xylanases, mannanases, and pectinases by the thermophilic fungus Thermomyces lanuginosus
- 1999
-
Ingår i: Enzyme and microbial technology. - 0141-0229 .- 1879-0909. ; 24:5-6, s. 355-361
-
Tidskriftsartikel (refereegranskat)abstract
- A group of 17 strains of the thermophilic fungus Thermomyces lanuginosus was examined for the production of xylanases, β-mannanases, arabinanases, and pectinases. All strains were found to be xylanolytic, and several were proven to be outstanding producers of microbial xylanase on glucuronoxylan and corn cobs. The strains hyperproducing xylanase secreted low amounts of xylan-debranching enzymes and did not produce β-mannan and arabinan-degrading enzyme systems. Only the strains showing lower xylanase production exhibited a higher degree of xylan utilization and also the ability to produce a mannanolytic enzyme system. One of the mannanolytic strains was found to be capable of producing arabinan-degrading enzymes. This strain also showed the best production of pectinolytic enzymes during growth on citrus pectin or sugar beet pulp. Some of the strains have good potential for use as sources of important industrial enzymes of high thermal stability.
|
|
| 22. |
- Topakas, Evangelos, et al.
(författare)
-
Production and partial characterisation of feruloyl esterase by Sporotrichum thermophile in solid-state fermentation
- 2003
-
Ingår i: Process Biochemistry. - 1359-5113 .- 1873-3298. ; 38:11, s. 1539-1543
-
Tidskriftsartikel (refereegranskat)abstract
- A number of factors affecting production of feruloyl esterase an enzyme that hydrolyse ester linkages of ferulic acid (FA) in plant cell walls, by the thermophylic fungus Sporotrichum thermophile under solid state fermentation (SSF) were investigated. Initial moisture content and type of carbon source were consecutively optimised. SSF in a laboratory horizontal bioreactor using the optimised medium allowed the production of 156 mU g−1 of carbon source, which compared favourably with those reported for the other micro-organisms. Optimal esterase activity was observed at pH 8 and 60 °C. The activity of the esterase was measured on an insoluble feruloylated hemicellulose substrate (de-starched wheat bran (DSWB)). De-esterification of wheat straw yielded loss of feruloyl esterase production even though the supplementation of free FA comparable to the alkali-extractable levels of FA found in wheat straw. Chromogenic (fluorogenic) 4-methylumbelliferyl ferulate was used to characterise the multienzyme component, after separation by isoelectric focusing and native PAGE electrophoresis. The zymograms indicated one major esterase activity exhibiting pI and molecular mass values 5 and 27 kDa, respectively.
|
|
| 23. |
- Topakas, Evangelos, et al.
(författare)
-
Production and partial characterization of xylanase from Sporotrichum thermophile under solid-state fermentation
- 2003
-
Ingår i: World Journal of Microbiology & Biotechnology. - 0959-3993 .- 1573-0972. ; 19:2, s. 195-198
-
Tidskriftsartikel (refereegranskat)abstract
- A number of factors affecting production of xylanase, by the thermophilic fungus Sporotrichum thermophile under solid state fermentation (SSF) were investigated. Initial moisture content and type of carbon source were consecutively optimized. Solid state fermentation in a laboratory horizontal bioreactor using the optimized medium allowed the production of 320 U g−1 of carbon source which compared favourably with those reported for other microorganisms. Optimal xylanase activity was observed at pH 5 and 70 °C. Chromogenic (fluorogenic) 4-methylumbelliferyl β-glycoside of xylobiose (MUX2) was used to characterize the xylanase multienzyme component, after separation by isoelectric focusing and native PAGE electrophoresis. The zymograms indicated one major xylanase fraction exhibiting pI and molecular mass values 4 and 90–120 kDa, respectively.
|
|
| 24. |
- Topakas, Evangelos, et al.
(författare)
-
Purification and characterization of a Fusarium oxysporum feruloyl esterase (FoFAE-I) catalysing transesterification of phenolic acid esters
- 2003
-
Ingår i: Enzyme and microbial technology. - 0141-0229 .- 1879-0909. ; 33:5, s. 729-737
-
Tidskriftsartikel (refereegranskat)abstract
- An extracellular feruloyl esterase (FoFAE-I) from the culture filtrates of Fusarium oxysporum F3 was purified to homogeneity by ion-exchange, hydrophobic interaction and gel filtration chromatographies. The protein corresponded to molecular mass and pI values of 31 kDa and 9.5, respectively. The enzyme was optimally active at pH 7.0 and 55 °C. The purified esterase was fully stable at pH 7.0–9.0 and temperature up to 30 °C. Determination of kcat/Km revealed that the enzyme hydrolysed methyl p-coumarate (MpCA) 4.5, 9, and 239 times more efficiently than methyl caffeate (MCA), methyl ferulate (MFA) and methyl sinapinate (MSA), respectively. The enzyme was active on substrates containing ferulic acid ester linked to the C-5 and C-2 linkages of arabinofuranose but showed preference for the ester at position 2. 4-Nitrophenyl-2-O-trans-feruloyl-α-l-arabinofuranoside (NPh-5-Fe-Araf) was hydrolysed 100 times more efficiently than 4-nitrophenyl-5-O-trans-feruloyl-α-l-arabinofuranoside (NPh-2-Fe-Araf). Ferulic acid (FA) was efficiently released from destarched wheat bran (DSWB) when the esterase was incubated together with xylanase from Sporotrichum thermophile (a maximum of 92% total ferulic acid released after 4 h incubation). FoFAE-I by itself could release FA but at a level almost five-fold lower than that obtained in the presence of xylanase. The potential of FAE-I for the synthesis of various phenolic acid esters was tested using as a reaction system a surfactantless microemulsions formed in ternary mixture consisting of n-hexane, 1-butanol and water.
|
|
