| 1. |
- 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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| 2. |
- Gkargkas, Konstantinos, et al.
(författare)
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Studies on a N-acetyl-β-d-glucosaminidase produced by Fusarium oxysporum F3 grown in solid-state fermentation
- 2004
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Ingår i: Process Biochemistry. - 1359-5113 .- 1873-3298. ; 39:11, s. 1599-1605
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Tidskriftsartikel (refereegranskat)abstract
- Fusarium oxysporum F3 produced N-acetyl-β-d-glucosaminidase when grown on wheat bran and chitin as carbon sources in solid-state fermentation. The initial moisture content and pH of growth medium were 65% and 6.0, respectively, and the enzyme yield 23.6 U g−1 carbon source. Two isozymes of N-acetyl-β-d-glucosaminidase, called N-acetyl-β-d-glucosaminidases I and II, were isolated from the culture filtrate of F. oxysporum F3. The filtrate was subjected to ammonium sulphate fractionation followed by anion exchange, gel filtration, hydrophobic interaction and cation exchange chromatography. The optimum pH of isozymes I and II was 5.0 and 6.0, respectively, whereas maximum activity of both isozymes was obtained at 40 °C. The Km of isozymes I and II was 49.6 and 48.6 μM and the Vmax 1.24 and 0.26 μmol mg−1 min−1, respectively, on p-nitrophenyl N-acetyl-β-d-glucosaminide as substrate. The molecular mass of isozymes I and II was calculated to be 67 kDa by SDS–PAGE.
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| 3. |
- 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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| 4. |
- Millati, R., et al.
(författare)
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Effect of pH, time and temperature of overliming on detoxification of dilute-acid hydrolyzates for fermentation by Saccharomyces cerevisiae
- 2002
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Ingår i: Process Biochemistry. - 1359-5113 .- 1873-3298. ; 38:4, s. 515-522
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Tidskriftsartikel (refereegranskat)abstract
- The effects of different variables in detoxification of a severely inhibiting dilute-acid hydrolyzate by overliming were investigated. Overliming was carried out by increasing the pH to 10, 11 or 12 at two different temperatures, 25 and 60 °C, holding the pH and temperature at constant values for different periods of time, 0, 1, 20 and 170 h, and then adjusting the pH to 5.5. All hydrolyzates were then fermented in batch cultivation by Saccharomyces cerevisiae in shake flasks, whereupon one was then selected for continuous cultivation in a bioreactor. The most significant effect of overliming was a sharp decrease in the concentration of furfural and hydroxymethylfurfural, whereas the concentration of acetic acid remained unchanged and the decrease in the total phenolic compounds was less than 30%. Detoxification at pH 12 for more than 1 h was effective, whereas no effect was obtained at pH 10 and the hydrolyzates had to remain at pH 11 for more than 20 h to become fermentable. On the other hand, decrease in sugar concentration during overliming was a serious problem at pH 12, especially at the higher temperature, where up to 70% sugars were degraded. The fermentability of a detoxified hydrolyzate was also tested in a continuous cultivation by immobilized S. cerevisiae in Ca-alginate. The hydrolyzate was fully fermentable at different dilution rates between 0.2 and 1.0 h-1.
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| 5. |
- Topakas, Evangelos, et al.
(författare)
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Production and partial characterisation of feruloyl esterase by Sporotrichum thermophile in solid-state fermentation
- 2003
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Ingår i: Process Biochemistry. - 1359-5113 .- 1873-3298. ; 38:11, s. 1539-1543
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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.
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