| 1. |
- Christakopoulos, Paul, et al.
(författare)
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Controlling simultaneous production of endoglucanase and beta-glucosidase by Fusarium oxysporum in submerged culture
- 1995
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Ingår i: Biotechnology letters. - 0141-5492 .- 1573-6776. ; 17:8, s. 883-888
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Tidskriftsartikel (refereegranskat)abstract
- The simultaneous production of endoglucanase and β-glucosidase by Fusarium oxysporum was investigated in submerged culture. Consecutive optimization of growth conditions resulted in the correction of large activity differences, observed during production of enzymes, and substantially enhanced low enzyme yields. At optimum growth conditions yields as high as 1650 and 232 U per g of carbon source of endoglucanase and β-glucosidase were obtained respectively competing favourably with those reported for microorganisms grown on the same carbon source. The most important kinetic characteristics of the enzymes were the high temperature optima of endoglucanase (60°C) and β-glucosidase (65°C) and the exceptionally high thermostability of endoglucanase. The latter enzyme retained 50% of the activity at pH 5.0 after approximately 6.5 h at 70°C
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| 2. |
- Christakopoulos, Paul, et al.
(författare)
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Production of an esterase from Fusarium oxysporum catalysing transesterification reactions in organic solvents
- 1998
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Ingår i: Process Biochemistry. - 1359-5113 .- 1873-3298. ; 33:7, s. 729-733
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Tidskriftsartikel (refereegranskat)abstract
- The production of an esterase by Fusarium oxysporum, grown on tomato skins as the sole carbon source, was studied in submerged and solid state cultures. Under optimum growth conditions, enzyme yields as high as 7·3 U/ml of culture medium and 19·4 U/g of carbon source were obtained. The esterase catalysed the synthesis of esters in organic solvents. Geraniol was transacetylated in hexane by the esterase using triacetyl as an acetyl donor. The geranyl acetate yield was 68%.
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| 3. |
- Hatzinikolaou, D.G, et al.
(författare)
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Production and partial characterisation of extracellular lipase from aspergillus niger
- 1996
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Ingår i: Biotechnology letters. - 0141-5492 .- 1573-6776. ; 18:5, s. 547-552
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Tidskriftsartikel (refereegranskat)abstract
- The production and certain kinetic characteristics of extracellular lipase from Aspergillus niger were investigated. It was possible to substantially enhance the activity of excreted lipase by optimising the interaction between carbon and nitrogen sources applying a two-parameter complete experimental design and response surface analysis. The enzyme was partially purified and a number of kinetic characteristics such as optimum pH and temperature, thermal and pH stability and K(m) were determined and discussed. The elevated levels of lipase activity (40.5 U/ml) found in this work competed favourably with most of those reported for lipase hyperproducing fungi.
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| 4. |
- Makropoulou, M., et al.
(författare)
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Factors affecting the specificity of beta-glucosidase from Fusarium oxysporum in enzymatic synthesis of alkyl-beta-D-glucosides
- 1998
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Ingår i: International Journal of Biological Macromolecules. - 0141-8130 .- 1879-0003. ; 22:2, s. 97-101
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Tidskriftsartikel (refereegranskat)abstract
- Factors affecting the specificity of β-glucosidase from Fusarium oxysporum in enzymatic synthesis of alkyl-β-d-glucosidesFusarium oxysporumβ-glucosidase has been used to catalyze the production of alkyl-β-d-glucosides from various disaccharides, based on the transglucosylation reaction, in the presence of primary, secondary and tertiary alcohols as glucosyl acceptors. Primary alcohols were found to be the best acceptors. The influence of the glucosyl donor concentration, as well as the enzyme specificity towards the cleaved glucosidic bond and the aglucone part of the donor, have also been investigated. The enzyme does not exhibit regiospecificity and seems to be unspecific towards the aglucone part. The specificity of the β linkage has been confirmed by proton nuclear magnetic resonance (1H NMR) analysis.
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| 5. |
- Stamatis, H., et al.
(författare)
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Studies on the synthesis of short-chain geranyl esters catalysed by Fusarium oxysporum esterase in organic solvents
- 1998
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Ingår i: Journal of Molecular Catalysis B. - 1381-1177 .- 1873-3158. ; 4:4, s. 229-236
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Tidskriftsartikel (refereegranskat)abstract
- A novel esterase isolated from Fusarium oxysporum was investigated for the synthesis of short-chain esters of geraniol by alcoholysis and direct esterification reactions in organic solvents. The enzyme was used as a dried powder (i.e., not immobilized). The reaction parameters affecting the enzyme behavior such as the nature of organic solvent and acyl donor, the concentration of substrates and the water activity of the system were studied. High yields (80–90%) were obtained by both approaches (alcoholysis and direct esterification) at low values of water activity (aw=0.11) in n-hexane. The enzyme retain its catalytic activity even after fifth reuse in n-hexane at aw=0.11, demonstrating its stability and efficiency under the conditions of this study.
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| 6. |
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| 7. |
- Tsitsimpikou, C., et al.
(författare)
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Studies of the effect of organic solvents on the stability of β-glucosidase from Fusarium oxysporum
- 1994
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Ingår i: Biotechnology letters. - 0141-5492 .- 1573-6776. ; 16:1, s. 57-62
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Tidskriftsartikel (refereegranskat)abstract
- The effect of organic solvents on the stability of β-glucosidase in a powder form, isolated fromFusarium oxysporum, has been studied using several organic solvents of different degree of hydrophobicity. It was found that β-glucosidase remains quite stable after a prolonged incubation in the presence of most of the organic solvents used, even at temperatures as high as 70°C. Only dimethyformamide (DMF) and tetrahydrofuran (THF) reduce considerably the enzyme activity in a short preincubation period. Studies on the effect of the pH of the buffer used prior to lyophilization, as well as of exogenous added water to the incubation mixture, on enzyme stability show that it is more stable in pH 5.0 and in the lowest water content. In addition it was found that the presence of glucose in the lyophilization procedure gives a significant protection to the enzyme when it is incubated for 30 h in pentanol and n-hexane.
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