| 1. |
- Gogou, Eleni, et al.
(författare)
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Effect of water activity on the thermal stability of Thermomyces lanuginosus xylanases for process time temperature integration
- 2010
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Ingår i: Journal of Food Engineering. - : Elsevier BV. - 0260-8774 .- 1873-5770. ; 100:4, s. 649-655
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Tidskriftsartikel (refereegranskat)abstract
- Three strains of the thermophilic fungus Thermomyces lanuginosus were used to produce β-xylanases. The thermal stability of these xylanases at low levels of water activity was studied. Isothermal inactivation experiments were performed in the temperature range of 100–130 °C. Reduction of water activity to 0.63 and as low as 0.13 had a drastic effect on the observed D and z-values. At water activity of 0.13 the D120 °C and z-values of the three xylanases ranged from 20.4 to 37.6 min and from 23.3 to 28.9 °C, respectively. The applicability of the developed kinetic models was tested under time–temperature profiles representative of typical thermal processes. The developed systems can be applied as time–temperature integrators (TTI) at this high thermal processing range. Calculations demonstrated that the use of a triple xylanase TTI system could provide acceptable F-values prediction for z-values lower than the achieved range.
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| 2. |
- Bakratsas, Georgios, et al.
(författare)
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Mycoprotein Production by Submerged Fermentation of the Edible Mushroom Pleurotus ostreatus in a Batch Stirred Tank Bioreactor Using Agro-Industrial Hydrolysate
- 2023
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Ingår i: Foods. - : MDPI. - 2304-8158. ; 12:12
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Tidskriftsartikel (refereegranskat)abstract
- The demand for cheap, healthy, and sustainable alternative protein sources has turned research interest into microbial proteins. Mycoproteins prevail due to their quite balanced amino acid profile, low carbon footprint and high sustainability potential. The goal of this research was to investigate the capability of Pleurotus ostreatus to metabolize the main sugars of agro-industrial side streams, such as aspen wood chips hydrolysate, to produce high-value protein with low cost. Our results indicate that P. ostreatus LGAM 1123 could be cultivated both in a C-6 (glucose)- and C-5(xylose)-sugar-containing medium for mycoprotein production. A mixture of glucose and xylose was found to be ideal for biomass production with high protein content and rich amino acid profile. P. ostreatus LGAM 1123 cultivation in a 4 L stirred-tank bioreactor using aspen hydrolysate was achieved with 25.0 ± 3.4 g L−1 biomass production, 1.8 ± 0.4 d−1 specific growth rate and a protein yield of 54.5 ± 0.5% (g/100 g sugars). PCA analysis of the amino acids revealed a strong correlation between the amino acid composition of the protein produced and the ratios of glucose and xylose in the culture medium. The production of high-nutrient mycoprotein by submerged fermentation of the edible fungus P. ostreatus using agro-industrial hydrolysates is a promising bioprocess in the food and feed industry. © 2023 by the authors.
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| 3. |
- Bakratsas, Georgios, et al.
(författare)
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Single-cell protein production by Pleurotus ostreatus in submerged fermentation†
- 2023
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Ingår i: Sustainable Food Technology. - : Royal Society of Chemistry. - 2753-8095. ; 1:3, s. 377-389
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Tidskriftsartikel (refereegranskat)abstract
- Agricultural land shrinkage, decreasing global water resources, population increase and malnutrition highlight the need for new food sources. Single-cell protein derived from microorganisms could be a solution to high protein demand. The aim of this work was to optimize the cultivation conditions for single-cell protein production by Pleurotus ostreatus LGAM 1123 in submerged cultures and valorize fiber sludge, a low cost industrial side stream from the pulp and paper industry, as a substrate for single-cell protein (SCP) production. A study on the effect of different cultivation conditions on fungal growth and protein production has been conducted. Response surface methodology was used to investigate the combined effect of the most important factors (glucose and yeast extract medium concentrations) and optimize the process. A maximum protein production of 10.0 ± 0.9 g L-1 was found for the submerged cultivation of the fungus in a 3.5 L stirred-tank bioreactor, while the biomass produced and its total protein content were 26.0 ± 2.0 g L-1 and 44.8 ± 0.8%, respectively. As an industrial application, a cellulosic hydrolysate obtained after enzymatic hydrolysis of fibre sludge in the optimized medium composition was used. Fibre sludge was shown to be an excellent feedstock for SCP production achieving productivity and protein content very similar to glucose fermentations. Single-cell protein of P. ostreatus presented higher amino acid scores compared to the recommended ones for valine, leucine, and aromatic amino acids in human nutrition. Therefore, P. ostreatus biomass could stand as an alternative vegan protein source due to its high protein content and amino acid composition.
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| 4. |
- Bennett, Neil A., et al.
(författare)
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Biochemical and catalytic properties of an endoxylanase purified from the culture filtrate of Thermomyces lanuginosus ATCC 46882
- 1998
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Ingår i: Carbohydrate Research. - 0008-6215 .- 1873-426X. ; 306:3, s. 445-455
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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.
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| 5. |
- Karageorgou, Dimitra, et al.
(författare)
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Benefits of supplementation with microbial omega-3 fatty acids on human health and the current market scenario for fish-free omega-3 fatty acid
- 2023
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Ingår i: Trends in Food Science & Technology. - : Elsevier. - 0924-2244 .- 1879-3053. ; 136, s. 169-180
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Forskningsöversikt (refereegranskat)abstract
- BackgroundGrowing evidence points to a link between specific fatty acids ingested through the diet and human health. Chain length, saturation degree, and position of double bonds in fatty acids determine their effect in humans. Omega-3 and omega-6 fatty acids have been recognized for their contribution to the prevention and/or treatment of diabetes, cancer, visual impairment, cardiovascular diseases, as well as neurological and musculoskeletal disorders.Scope and approachHumans cannot synthesize these fatty acids in sufficient amounts and need to absorb them through the diet. Oleaginous microalgae constitute a promising, sustainable source of such fatty acids, as they can accumulate up to 85% of lipids on a cell dry weight basis.Key findings and conclusionsThe present review summarizes the potential of oleaginous microalgae as a convenient, economical, and sustainable source of polyunsaturated fatty acids, and explores their beneficial role in human health. The growing prevalence of cardiovascular diseases and changing dietary preferences are driving the increasing demand for microbial omega-3 fatty acids. Following the COVID-19 pandemic, the importance of a healthy immune system has further strengthened the market for omega-3 fatty acids.
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| 6. |
- Karageorgou, Dimitra, et al.
(författare)
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Heterotrophic Cultivation of the Cyanobacterium Pseudanabaena sp. on Forest Biomass Hydrolysates toward Sustainable Biodiesel Production
- 2022
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Ingår i: Microorganisms. - : MDPI. - 2076-2607. ; 10:9
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Tidskriftsartikel (refereegranskat)abstract
- Environmental pollution, greenhouse gas emissions, depletion of fossil fuels, and a growing population have sparked a search for new and renewable energy sources such as biodiesel. The use of waste or residues as substrates for microbial growth can favor the implementation of a biorefinery concept with reduced environmental footprint. Cyanobacteria constitute microorganisms with enhanced ability to use industrial effluents, wastewaters, forest residues for growth, and concomitant production of added-value compounds. In this study, a recently isolated cyanobacterium strain of Pseudanabaena sp. was cultivated on hydrolysates from pretreated forest biomass (silver birch and Norway spruce), and the production of biodiesel-grade lipids was assessed. Optimizing carbon source concentration and the (C/N) carbon-to-nitrogen ratio resulted in 66.45% w/w lipid content when microalgae were grown on glucose, compared to 62.95% and 63.79% w/w when grown on spruce and birch hydrolysate, respectively. Importantly, the lipid profile was suitable for the production of high-quality biodiesel. The present study demonstrates how this new cyanobacterial strain could be used as a biofactory, converting residual resources into green biofuel.
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| 7. |
- Katapodis, Petros, et al.
(författare)
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Biochemical and catalytic properties of an endoxylanase purified from the culture filtrate of Sporotrichum thermophile
- 2003
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Ingår i: Carbohydrate Research. - 0008-6215 .- 1873-426X. ; 338:18, s. 1881-1890
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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.
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| 8. |
- Katapodis, Petros, et al.
(författare)
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Enzymic production of a feruloylated oligosaccharide with antioxidant activity from wheat flour arabinoxylan
- 2003
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Ingår i: European Journal of Nutrition. - : Springer Science and Business Media LLC. - 1436-6207 .- 1436-6215. ; 42:1, s. 55-60
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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.
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| 9. |
- Katapodis, Petros, et al.
(författare)
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Enzymic production of aldopentauronic acid and use as bioregulator in plant airlift bioreactors
- 2003
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Ingår i: Journal of Bioscience and Bioengineering. - 1389-1723 .- 1347-4421. ; 95:6, s. 630-632
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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.
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| 10. |
- Katapodis, Petros, et al.
(författare)
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Enzymic production of feruloyl xylo-oligosaccharides from corn cobs by a family 10 xylanase from Thermoascus aurantiacus
- 2008
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Ingår i: Lebensmittel-Wissenschaft + Technologie. - : Elsevier BV. - 0023-6438 .- 1096-1127. ; 41:7, s. 1239-1243
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Tidskriftsartikel (refereegranskat)abstract
- Feruloyl xylo-oligosaccharides (FeXOSs) were obtained from corn cobs (CCs) by treatment with a Thermoascus aurantiacus family 10-β-d-endoxylanase. CCs subjected to a sonication (ST-CC) or an autoclave treatment in order to enhance enzymic access and FeXOS production. Enzymic FeXOS production was increased by CCs thermal treatment up to 3.5 times. The kinetic parameters KE and Vmax, describing enzyme-dependent production rates of FeXOSs from CCs, were estimated at 130±20 nM and 290±10 nM h−1, respectively. The reaction parameters affecting the FeXOS production, such as substrate concentration, enzyme loading and reaction time, have been investigated. The maximum FeXOS production was observed after 24 h incubation of 100 g L−1 AT-CC with 570 nM xylanase. The obtained yield was 12 μmol of FeXOSs per gram of CC.
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