| 1. |
- Nacos, M.K., et al.
(författare)
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Kenaf xylan – A source of biologically active acidic oligosaccharides
- 2006
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Ingår i: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617 .- 1879-1344. ; 66:1, s. 126-134
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Tidskriftsartikel (refereegranskat)abstract
- Two xylose-rich hemicellulose fractions were obtained from kenaf wood (Hibiscus cannabinus L.) through a series of sequential extractions which dissociated xylans from other cell wall components. These fractions were subsequently used as substrates for the production of biologically active aldouronic acids. Incubation of the xylans with a family 10 Thermoascus aurantiacus endoxylanase resulted in the isolation of an aldotetrauronic acid as the main acidic oligosaccharide in the hydrolysis products. Enzymic hydrolysis with a family 11 Sporotrichum thermophile endoxylanase instead resulted in the isolation of a aldopentauronic acid as the main acidic oligosaccharide. The identity and purity of both xylans and aldouronic acids were assessed with solid-state FT-IR, solid-state and solution 13C NMR spectroscopy.
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| 2. |
- Vardakou, M., et al.
(författare)
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Synergy between enzymes involved in the degradation of insoluble wheat flour arabinoxylan
- 2004
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Ingår i: Innovative Food Science & Emerging Technologies. - 1466-8564 .- 1878-5522. ; 5:1, s. 107-112
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Tidskriftsartikel (refereegranskat)abstract
- Two microbial endo-β-1,4-xylanases (EXs, EC 3.2.1.8) belonging to glycanase families 10 and 11 were examined for their ability to release ferulic acid (FA) from water-unextractable arabinoxylan (WU-AX) in the presence of a feruloyl esterase (FoFAE-II) from Fusarium oxysporum. WU-AX was incubated with different levels of a Thermoascus aurantiacus family 10 (XYLI) and a Sporotrichum thermophile family 11 (XYLA) endoxylanases. At 10 g/l arabinoxylan, enzyme concentrations (KE values) needed to obtain half-maximal hydrolysis rates for FA release were 0.18 and 0.44 nM for the xylanases from T. aurantiacus and S. thermophile, respectively. Determination of Vmax/KE revealed that the family 10 enzyme performed 4.3 times more efficiently than the family 11 enzyme in liberation of FA when a feruloyl esterase is present. Molecular weights of the products formed were assessed and separation of feruloyl-oligosaccharides was achieved by anion-exchange and size-exclusion chromatography (SEC). The results showed that the degradation of the xylan backbone was influenced strongest by the action of xylanases while the presence of the esterase mainly resulted in the release of ferulic acid from the produced short chain feruloylated xylo-oligosaccharides by the action of xylanases
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| 3. |
- Cheilas, T, et al.
(författare)
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Hemicellulolytic activity of Fusarium oxysporum grown on sugar beet pulp. Production of extracellular arabinanase
- 2000
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Ingår i: Process Biochemistry. - 1359-5113 .- 1873-3298. ; 35:6, s. 557-561
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Tidskriftsartikel (refereegranskat)abstract
- Fusarium oxysporum F3 exhibited hemicellulolytic enzymic activity when grown on sugar beet pulp, a by-product of the sugar industry. The growth medium was specifically optimised for enhanced production of extracellular arabinanase. The optimum medium contained sugar beet pulp (4%, w/v) and corn steep liquor (6%, v/v) as carbon and nitrogen sources, respectively. Arabinanase activity as high as 0.25 U/ml of culture was obtained, which compared favourably to those reported for other microorganisms. Optimal arabinanase activity was observed at pH 6-7 and 50 °C. Investigation of the degradation of the main components of sugar beet pulp showed that arabinose containing polysaccharides and pectin were first degraded, followed by the glucose-containing polysaccharides.
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| 4. |
- Christakopoulos, Paul, et al.
(författare)
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Antimicrobial activity of acidic xylo-oligosaccharides produced by family 10 and 11 endoxylanases
- 2003
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Ingår i: International Journal of Biological Macromolecules. - 0141-8130 .- 1879-0003. ; 31:4-5, s. 171-175
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Tidskriftsartikel (refereegranskat)abstract
- Acidic oligosaccharides were obtained from birchwood xylan by treatment with a Thermoascus aurantiacus family 10 and a Sporotrichum thermophile family 11 endoxylanases. The main difference between the products liberated by xylanases of family 10 and 11 concerned the length of the products containing 4-O-methyl-d-glucuronic acid. The xylanase from T. aurantiacus liberate from glucuronoxylan an aldotetrauronic acid as the shortest acidic fragment in contrast with the enzyme from S. thermophile, which liberated an aldopentauronic acid. Acidic xylooligosaccharides were separated from the hydrolysate by anion-exchange and size-exclusion chromatography (SEC) and the primary structure was determined by 13C NMR spectroscopy. The acidic xylo-oligosaccharides were tested against three Gram-positive and three Gram-negative aerobically grown bacteria, as well as against Helicobacterpylori. Aldopentauronic acid was proved more active against the Gram-positive bacteria and against H. pylori.
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| 5. |
- Christakopoulos, Paul, et al.
(författare)
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Purification and characterization of an extracellular α-L- arabinofuranosidase from Fusarium oxysporum
- 2000
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Ingår i: Applied Biochemistry and Biotechnology. - 0273-2289 .- 1559-0291. ; 87:2, s. 127-133
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Tidskriftsartikel (refereegranskat)abstract
- An α-L-arabinofuranosidase from Fusarium oxysporum F3 was purified to homogeneity by a two-step ion exchange intercalated by a gel filtration chromatography. The enzyme had a molecular mass of 66 kDa and was optimally active at pH 6.0 and 60°C. It hydrolyzed aryl α-L-arabinofuranosides and cleaved arabinosyl side chains from arabinoxylan and arabinan. There was a marked synergistic effect between the α-L-arabinofuranosidase and an endo-(1→4)-β-D-xylanase produced by F. oxysporum in the extensive hydrolysis of arabinoxylan.
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| 6. |
- Kalogeris, E, et al.
(författare)
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Production and characterization of cellulolytic enzymes from the thermophilic fungus Thermoascus aurantiacus under solid state cultivation of agricultural wastes
- 2003
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Ingår i: Process Biochemistry. - 1359-5113 .- 1873-3298. ; 38:7, s. 1099-1104
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Tidskriftsartikel (refereegranskat)abstract
- Extracellular cellulolytic enzymes were produced under solid state cultivation by the thermophilic fungus Thermoascus aurantiacus and characterized. Elevated levels of endoglucanase and β-glucosidase activities were produced simultaneously by optimization of growth factors. Under optimal growth conditions, 1572 U endoglucanase and 101.6 U β-glucosidase per g of carbon source were obtained. Chromogenic (fluorogenic) 4-methylumbelliferyl-β-glycosides of glucose (MUG) and cellobiose (MUG2) were used to characterize the cellulolytic multienzyme components after separation by isoelectric focusing. The zymogram indicated one endoglucanase and one β-glucosidase with pI values 3.5 and 3.9, respectively. Both enzymes exhibited significant thermostability, with half-lives of 42 and 18 min, respectively, at 80°C
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| 7. |
- Katapodis, P., et al.
(författare)
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Biodegradation of indole at high concentration by persolvent fermentation with the thermophilic fungus Sporotrichum thermophile
- 2007
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Ingår i: International Biodeterioration & Biodegradation. - : Elsevier BV. - 0964-8305 .- 1879-0208. ; 60:4, s. 267-272
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Tidskriftsartikel (refereegranskat)abstract
- Indole and its derivatives form a class of toxic recalcitrant environmental pollulants. Sporotrichum thermophile was grown in a persolvent fermentation system containing a large amount of indole. The medium contained up to 20% by volume soybean oil and up to 2 g L−1 indole. Most of the indole was partitioned in the organic solvent layer. When the organism was grown in the medium containing indole at 1 g L−1, indole was totally consumed after 6 days. Under a fed–batch fermentation process where daily batches of indole (1 g L−1) supplemented the microbial culture for 4 days, the biodegradation level was 3.0 g L−1. These values make this process promising and worthy of further investigation for the microbial degradation of other toxic compounds.
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| 8. |
- Katapodis, P., et al.
(författare)
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Biosynthesis of fructo-oligosaccharides by Sporotrichum thermophile during submerged batch cultivation in high sucrose media
- 2004
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Ingår i: Applied Microbiology and Biotechnology. - : Springer Science and Business Media LLC. - 0175-7598 .- 1432-0614. ; 63:4, s. 378-382
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Tidskriftsartikel (refereegranskat)abstract
- A feruloyl esterase (StFAE-A) produced by Sporotrichum thermophile was purified to homogeneity. The purified homogeneous preparation of native StFAE-A exhibited a molecular mass of 57.0±1.5 kDa, with a mass of 33±1 kDa on SDS-PAGE. The pI of the enzyme was estimated by cation-exchange chromatofocusing to be at pH 3.1. The enzyme activity was optimal at pH 6.0 and 55–60 °C. The purified esterase was stable at the pH range 5.0–7.0. The enzyme retained 70% of activity after 7 h at 50 °C and lost 50% of its activity after 45 min at 55 °C and after 12 min at 60 °C. Determination of k cat/K m revealed that the enzyme hydrolyzed methyl p-coumarate 2.5- and 12-fold more efficiently than methyl caffeate and methyl ferulate, respectively. No activity on methyl sinapinate was detected. The enzyme was active on substrates containing ferulic acid ester linked to the C-5 and C-2 linkages of arabinofuranose and it hydrolyzed 4-nitrophenyl 5-O-trans-feruloyl-α-l-arabinofuranoside (NPh-5-Fe-Araf) 2-fold more efficiently than NPh-2-Fe-Araf. Ferulic acid (FA) was efficiently released from destarched wheat bran when the esterase was incubated together with xylanase from S. thermophile (a maximum of 34% total ferulic acid released after 1 h incubation). StFAE-A by itself could release FA, but at a level almost 47-fold lower than that obtained in the presence of xylanase. The potential of StFAE-A for the synthesis of various phenolic acid esters was tested using a ternary water-organic mixture consisting of n-hexane, 1-butanol and water as a reaction system.
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| 9. |
- Katapodis, P., et al.
(författare)
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Induction and partial characterization of intracellular β from Thermoascus aurantiacus and its application in the synthesis of 6-kestose
- 2004
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Ingår i: World Journal of Microbiology & Biotechnology. - : Springer Science and Business Media LLC. - 0959-3993 .- 1573-0972. ; 20:7, s. 667-672
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Tidskriftsartikel (refereegranskat)abstract
- Production of beta-fructofuranosidase from the thermophilic fungus Thermoascus aurantiacus was enhanced by optimization of the type of nitrogen source as well as the type and concentration of carbon source. Submerged batch cultivation in a laboratory bioreactor (7 l) using the optimized medium allowed the production of 85 mU/ml of beta-fructofuranosidase. The enzyme showed both transfructosylating and hydrolytic activities and was optimally active at 60 degreesC and pH 5.0. The enzyme showed the ability to catalyse the synthesis of 1-kestose and the reaction was maximized at 30% (w/v) initial sucrose concentration.
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| 10. |
- Katapodis, P., et al.
(författare)
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Optimization of xylanase production by Sporotrichum thermophile in corn cobs using response surface methodology
- 2006
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Ingår i: Engineering in Life Sciences. - : Wiley. - 1618-0240 .- 1618-2863. ; 6:4, s. 410-415
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Tidskriftsartikel (refereegranskat)abstract
- A 32 central composite experimental design was performed with the aim of optimizing the production of xylanase by Sporotrichum thermophile grown on corn cobs in submerged cultures. Various carbon and nitrogen sources were consecutively optimized, and corn cobs and ammonium phosphate concentrations were selected as substrates to test the effect of two variables, i.e., both substrate concentrations, on xylanase production. A second-order quadratic model and a response surface method showed that the optimum conditions for xylanase production were 2.7 % [w/v] corn cobs and 0.7 % [w/v] ammonium phosphate. These optimum conditions were transferred to 7 L bioreactors, where activities as high as 56 U/mL were obtained.
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| 11. |
- Katapodis, P, et al.
(författare)
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Production of acidic xylo-oligosaccharides by a family 10 endoxylanase from Thermoascus aurantiacus and use as plant growth regulators
- 2002
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Ingår i: Biotechnology letters. - 0141-5492 .- 1573-6776. ; 24:17, s. 1413-1416
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Tidskriftsartikel (refereegranskat)abstract
- Neutral and acidic oligosaccharides were obtained from birchwood xylan by treatment with an endoxylanase, family 10 class, from Thermoascus aurantiacus. The main acidic xylooligosaccharide (aldotetrauronic acid) was separated from the hydrolysate by anion-exchange and size-exclusion chromatography and the primary structure was determined by 13C NMR spectroscopy. The aldotetrauronic yield was 15% (w/w) of the total solubilised sugars. The addition of purified aldoterauronic acid at 1.6-16 mg 1 -1 growth medium, induced callus and somatic embryogenesis in culture explants of common mallow (Malva silvestris L.) and cotton (Gosssypium hirsutum).
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| 12. |
- Katapodis, P, et al.
(författare)
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Xylanases as a tool for the production of novel phytopharmaceuticals
- 2005
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Ingår i: NutraCos. - 1720-4011. ; 4:2, s. 17-21
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Tidskriftsartikel (refereegranskat)abstract
- Results are presented of a study on the production and biological activities of acidic and feruloyl oligosaccharides from xylan by family 10 and 11 endoxylanases [endo-1,4-β-xylanase] from Thermoascus aurantiacus and Sporotrichum thermophile [Myceliophthora thermophila]. Both family 10 and 11 endoxylanases were able to release branched xylooligosaccharides from xylan. Feruloyl oligosaccharides acted as antioxidants and showed protective effects against copper-catalysed peroxidation of low-density lipoproteins. Acidic xylooligosaccharides, products of 4-O-methyl-D-glucurono-D-xylan hydrolysis, functioned as plant growth regulators and antibacterial agents. Aldotetrauronic acid induced callus and somatic embryogenesis in culture explants of common mallow (Malva sylvestris) and cotton (Gossypium hirsutum). Aldopentauronic acid caused an increase in both the number of regenerants and their fresh weight to cucumber (cultivars Stella and Gilda) liquid culture in plant airlift bioreactors. Both acidic xylooligosaccharides were active against Bacillus cereus, Micrococcus flavus and Helicobacter pylori.
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| 13. |
- Papaspyridi, Lefki Maria, et al.
(författare)
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Fatty acid profiles of Pleurotus ostreatus and Ganoderma australe grown naturally and in a batch reactor
- 2013
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Ingår i: Acta alimentaria. - 0139-3006 .- 1588-2535. ; 42:3, s. 328-337
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Tidskriftsartikel (refereegranskat)abstract
- Non-polar lipid content and fatty acid (FA) composition of the commercial edible strain of Pleurotus ostreatus and the medicinal wild strain of Ganoderma australe were determined. A comparison of the FA profile was conducted between mycelium grown under optimum bioreactor conditions and naturally occurring fruit bodies in both species. Both strains contained unsaturated FA (UFA), amounting to 55–77% of total FA content, whereas the proportion of essential FA was contributive, permitting their consideration as potential food ingredients. Bioreactor process resulted in a significant total FA content increase accompanied with a considerable effect on ratios of nutritional interest (MUFA/SFA, PUFA/SFA, oleic/linoleic).
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