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See detailSugar beet leaves as new source of hydroperoxide lyase in a bioprocess producing green-note aldehydes.
Rabetafika, Holy-Nadia ULg; Gigot, Cédric ULg; Fauconnier, Marie-Laure ULg et al

in Biotechnology Letters (2008), 30(6), 1115-9

Hydroperoxide lyase activity was found in sugar beet leaves. Its optimum pH and temperature were, respectively, 6.7 and 22 degrees C. Under these conditions, conversion of linolenic acid 13-hydroperoxide ... [more ▼]

Hydroperoxide lyase activity was found in sugar beet leaves. Its optimum pH and temperature were, respectively, 6.7 and 22 degrees C. Under these conditions, conversion of linolenic acid 13-hydroperoxide to cis-3-hexenal with a maximum yield of 80% was reached after only 2 min. The stability of cis-3-hexenal was improved by acidifying the reaction medium. Based on these studies, a bioprocess producing green-note aldehydes in a laboratory-scale was achieved. [less ▲]

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See detailCulture And Spray-Drying Of Tsukamurella Paurometabola C-924: Stability Of Formulated Powders
Hernandez, A.; Weekers, F.; Mena, J. et al

in Biotechnology Letters (2007), 29(11),

The nematocidal agent, Tsukamurella paurometabola C-924, was cultured in a 300 l bioreactor. Spray-dried formulations of this microorganism were prepared using sucrose. At an outlet temperature 628C ... [more ▼]

The nematocidal agent, Tsukamurella paurometabola C-924, was cultured in a 300 l bioreactor. Spray-dried formulations of this microorganism were prepared using sucrose. At an outlet temperature 628C, survival rates between 12 and 85% were reached with sucrose up to 10% (w/w). The stability study of the powders showed that the best storage condition was at 48C under vacuum. A new method for the calculation of cell death order for bacteria stored at low temperatures was developed. Powders stored under vacuum showed an Arrhenius behavior in relation to cell death kinetics. [less ▲]

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See detailMutational Analysis Of The Tre2 Oncogene Encoding An Inactive Rabgap
Bizimungu, C.; Thomas, Annick ULg; Brasseur, Robert ULg et al

in Biotechnology Letters (2007), 29(12), 1927-37

The TRE2 oncoprotein is structurally related to the RabGAP (GTPase-activating protein) family. However, TRE2 seems enzymatically inactive. Two regions are important for its lack of GAP activity. First ... [more ▼]

The TRE2 oncoprotein is structurally related to the RabGAP (GTPase-activating protein) family. However, TRE2 seems enzymatically inactive. Two regions are important for its lack of GAP activity. First, the TBC domain, forming the catalytically active domain of RabGAPs, is non-functional in the oncoprotein. Also involved in TRE2 inactivity is the 93-aa region flanking the TBC domain on the C-terminal side. In order to identify the residues responsible for non-functionality, we performed hydrophobic cluster analysis of the oncoprotein sequence, combined with secondary structure prediction, receptor-binding domain analysis, and a tilted peptide calculation. These analyses were complemented with site-directed and random mutagenesis experiments. On the basis of our data, we hypothesize that the lack of secondary structure of the region flanking the TBC domain in TRE2 may explain why this region plays a role in the lack of GAP activity, even when a potentially functional TBC domain is present. [less ▲]

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See detailExpression of alternansucrase in potato plants
Jacon, Géraldine ULg; Vincken, Jean-Paul; Suurs, Luc et al

in Biotechnology Letters (2007), 29

Alternan, which consists of alternating alpha(1 - 3)/alpha (1 - 6)-linked glucosyl residues, was produced in potato tubers by expressing a mature alternansucrase (Asr) gene from Leuconostoc mesenteroides ... [more ▼]

Alternan, which consists of alternating alpha(1 - 3)/alpha (1 - 6)-linked glucosyl residues, was produced in potato tubers by expressing a mature alternansucrase (Asr) gene from Leuconostoc mesenteroides NRRL B-1355 in potato. Detection of alternan was performed by enzyme-linked immunosorbent assay in tuber juices, revealing a concentration between 0.3 and 1.2 mg g–1 fresh wt. The Asr transcript levels correlated well with alternan accumulation in tuber juices. It appeared that the expression of sucrose-regulated starch- synthesizing genes (ADP-glucose pyrophosphorylase subunit S and granule-bound starch synthase I) was down-regulated. Despite this, the physico- chemical properties of the transgenic starches were unaltered. These results are compared to those obtained with other transgenic potato plants producing mutan [alpha (1 - 3)-linked glucosyl residues and dextran [alpha (1 - 6)-linked glucosyl residues]. [less ▲]

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See detailProduction, Formulation And Antagonistic Activity Of The Biocontrol Like-Yeast Aureobasidium Pullulans Against Penicillium Expansum
Mounir, R.; Durieux, A.; Bodo, E. et al

in Biotechnology Letters (2007), 29(4), 553-559

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See detailThe Tre2 Oncoprotein, Implicated In Ewing'S Sarcoma, Interacts With Two Components Of The Cytoskeleton
Dechamps, C.; Bach, S.; Portetelle, Daniel ULg et al

in Biotechnology Letters (2006), 28(4),

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See detailApplication of a novel oscillatory flow micro-bioreactor to the production of γ-decalactone in a two immiscible liquid phase medium
Reis, N.; Gonçalves, C. N.; Aguedo, Mario ULg et al

in Biotechnology Letters (2006), 28(7), 485-490

A novel micro-bioreactor based on the oscillatory flow technology was applied to the scale-down of the biotechnological production of γ-decalactone. A decrease up to 50% of the time required to obtain the ... [more ▼]

A novel micro-bioreactor based on the oscillatory flow technology was applied to the scale-down of the biotechnological production of γ-decalactone. A decrease up to 50% of the time required to obtain the maximum concentration of the compound was observed, when compared with other scaled-down platforms (stirred tank bioreactor or shake flask). A three-fold increase in γ-decalactone productivity was obtained by increasing oscillatory mixing intensity from Re o ∼482 to Re o ∼1447. This was presumably related to the effective contribution of the reactor geometry to enhanced mass transfer rates between the two immiscible liquid phases involved in the process by increasing the interfacial area. © Springer 2006. [less ▲]

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See detailMethyl Oleate Modulates Lip2 Expression In The Lipolytic Yeast Yarrowia Lipolytica
Fickers, Patrick; Destain, Jacqueline ULg; Thonart, Philippe ULg

in Biotechnology Letters (2005), 27(22),

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See detailSurface properties of Yarrowia lipolytica and their relevance to γ-decalactone formation from methyl ricinoleate
Aguedo, Mario ULg; Waché, Y.; Belin, J.-M. et al

in Biotechnology Letters (2005), 27(6), 417-422

The surface of the lipid-degrading yeast, Yarrowia lipolytica, was characterized by contact angle and zeta potential (ζ) measurements. The cells were mainly hydrophilic with a negative charge that was ... [more ▼]

The surface of the lipid-degrading yeast, Yarrowia lipolytica, was characterized by contact angle and zeta potential (ζ) measurements. The cells were mainly hydrophilic with a negative charge that was only affected from pH 2 to 4. To study the effects of the surface charges on the biotransformation of methyl ricinoleate into the aroma compound, γ-decalactone, the ζ values of the substrate droplets were modified by adding a cationic surfactant into the medium at concentrations that did not diminish cell viability: the adhesion of the lipid substrate to the cells was increased but not the overall performance of the process, therefore the adhesion is not the rate limiting here. Our methodology offers interesting perspectives for further applications. © Springer 2005. [less ▲]

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See detailDecalactone production by Yarrowia lipolytica under increased O2 transfer rates
Aguedo, Mario ULg; Gomes, N.; Garcia, E. E. et al

in Biotechnology Letters (2005), 27(20), 1617-1621

Yarrowia lipolytica converts methyl ricinoleate to γ-decalactone, a high-value fruity aroma compound. The highest amount of 3-hydroxy-γ- decalactone produced by the yeast (263 mg∈l-1) occurred by ... [more ▼]

Yarrowia lipolytica converts methyl ricinoleate to γ-decalactone, a high-value fruity aroma compound. The highest amount of 3-hydroxy-γ- decalactone produced by the yeast (263 mg∈l-1) occurred by increasing the k L a up to 120 h-1 at atmospheric pressure; above it, its concentration decreased, suggesting a predominance of the activity of 3-hydroxyacyl-CoA dehydrogenase. Cultures were grown under high-pressure, i.e., under increased O2 solubility, but, although growth was accelerated, γ-decalactone production decreased. However, by applying 0.5 MPa during growth and biotransformation gave increased concentrations of dec-2-en-4-olide and dec-3-en-4-olide (70 mg∈l -1). © Springer 2005. [less ▲]

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See detailSynthesis of novel D-glucuronic acid fatty esters using Candida antarctica lipase in tert-butanol
Moreau, Benoit; Lognay, Georges ULg; Blecker, Christophe ULg et al

in Biotechnology Letters (2004), 26(5), 419-424

Glucuronic acid n-alkyl esters, a novel class of promising biosurfactants and their corresponding glucose esters with the same side-chain length, were synthesized by direct esterification in a non-aqueous ... [more ▼]

Glucuronic acid n-alkyl esters, a novel class of promising biosurfactants and their corresponding glucose esters with the same side-chain length, were synthesized by direct esterification in a non-aqueous phase (tert-butanol) using an immobilized lipase. [less ▲]

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See detailAlkaloid accumulation in Catharanthus roseus cell suspension cultures fed with stemmadenine
El-Sayed, M.; Choi, Y. H.; Frederich, Michel ULg et al

in Biotechnology Letters (2004), 26(10), 793-798

Feeding stemmadenine to Catharanthus roseus cell suspension culture resulted in the accumulation of catharanthine, tabersonine and condylocarpine. Condylocarpine is not an intermediate in the pathway to ... [more ▼]

Feeding stemmadenine to Catharanthus roseus cell suspension culture resulted in the accumulation of catharanthine, tabersonine and condylocarpine. Condylocarpine is not an intermediate in the pathway to catharanthine or tabersonine when it is fed to the cultures. The results support the hypothesis that stemmadenine is an intermediate in the pathway to catharanthine and tabersonine. [less ▲]

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See detailA colorimetric method for the determination of lipase activity in soil
Margesin, R.; Feller, Georges ULg; Hammerle, M. et al

in Biotechnology Letters (2002), 24(1), 27-33

A colorimetric method for the determination of lipase activity in soil has been developed. Using p-nitrophenyl butyrate as substrate, soil samples are incubated at 30 degreesC and pH 7.25 for 10 min ... [more ▼]

A colorimetric method for the determination of lipase activity in soil has been developed. Using p-nitrophenyl butyrate as substrate, soil samples are incubated at 30 degreesC and pH 7.25 for 10 min. After cooling on ice and centrifugation, the released p-nitrophenol is determined at 400 nm. To allow for the adsorption of p-nitrophenol onto soil, a calibration curve is prepared in the presence of soil. [less ▲]

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See detailInteraction of odorous lactones with phospholipids: Implications in toxicity towards producing yeast cells
Aguedo, Mario ULg; Beney, L.; Waché, Y. et al

in Biotechnology Letters (2002), 24(23), 1975-1979

Some lactonic aroma compounds, that can be produced industrially by microorganisms, become toxic towards the producing cells as these compounds reach high concentrations in the culture medium. To ... [more ▼]

Some lactonic aroma compounds, that can be produced industrially by microorganisms, become toxic towards the producing cells as these compounds reach high concentrations in the culture medium. To determine the manner by which these metabolites may influence yeast physiology, the effects of four lactones (concentration range of 100 to 300 mg l-1) on the growth of Yarrowia lipolytica and on the phase behaviour of deuterated dimyristoylphos-phatidylcholine (DMPC-d27) were studied. The results showed that the hydrophobic lactones decrease the phase transition temperature (Tm) of DMPC-d27 bilayers and that Tm decrease (ΔTm) was related to the inhibitory action of the lactones on yeast growth (evaluated by the lag time). These results suggest that whatever the lactone, a ΔTm of at least 2.5°C resulted in a total growth inhibition: this implicates the lactone-phospholipids interaction in the mechanism of yeast growth inhibition. The test used in the present study may be a predicting method to assess the in vivo action of potential membrane active compounds. [less ▲]

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See detailA recombinant beta-O-glucosidase from Caldocellum saccharolyticum to hydrolyse desulfo-glucosinolates
Wathelet, Jean-Paul ULg; Iori, R.; Leoni, O. et al

in Biotechnology Letters (2001), 23(6), 443-446

Glucosinolates, natural compounds found in Brassicaceae, can easily be transformed into desulfo-glucosinolates by action of Helix pomatia sulfatase. The recombinant beta -O-glucosidase from Caldocellum ... [more ▼]

Glucosinolates, natural compounds found in Brassicaceae, can easily be transformed into desulfo-glucosinolates by action of Helix pomatia sulfatase. The recombinant beta -O-glucosidase from Caldocellum saccharolyticum does not catalyse glucosinolate degradation but can hydrolyse desulfo-glucosinolates (thio-D-glucosidic substrates) to produce the corresponding pure nitriles, including valuable homochiral representatives. [less ▲]

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See detailConversion of green note aldehydes into alcohols by yeast alcohol dehydrogenase
Fauconnier, Marie-Laure ULg; Mpambara, A.; Delcarte, Jérôme et al

in Biotechnology Letters (1999), 21(7), 629-633

‘Green note’ aldehydes were successfully reduced into their corresponding alcohol by commercial yeast alcohol dehydrogenase. Among different yeasts tested for their ability to convert (Z)-3-hexenal into ... [more ▼]

‘Green note’ aldehydes were successfully reduced into their corresponding alcohol by commercial yeast alcohol dehydrogenase. Among different yeasts tested for their ability to convert (Z)-3-hexenal into (Z)-3-hexenol, Pichia anomala gave the best results. Conversion yields higher than 90% were also obtained by directly conducting the reaction in the medium where (Z)-3-hexenal is produced by the action of lipoxygenase and hydroperoxide lyase on <br />linolenic acid. [less ▲]

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See detailImprovement Of Lipase Production From Yarrowia Lipolytica
Destain, Jacqueline ULg; Weber, D.; Thonart, Philippe ULg

in Biotechnology Letters (1997), 19(2),

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See detailElectrical microenvironment influence on the hydrolytic activity of free and immobilised Yarrowia lipolytica lipase
Paquot, Michel ULg; Deleu, Magali ULg; Beaufils, C. et al

in Biotechnology Letters (1996), 18(1), 73-78

The role of electrical properties of interfaces upon the activity of free and immobilised Yarrowia lipolytica lipase has been investigated. Sodium taurocholate and Sedipur 400, an anionic polyacrylamide ... [more ▼]

The role of electrical properties of interfaces upon the activity of free and immobilised Yarrowia lipolytica lipase has been investigated. Sodium taurocholate and Sedipur 400, an anionic polyacrylamide, enhance the negative character of the fatty droplets of substrate and tend to improve the lipolytic activity while the cationic polyacrylamide (Sedipur 900) has opposite effects. Ca+ which reduces the fatty droplets charge as Sedipur 900, is however a good activator of the enzyme. The role of electrical properties on the optimum pH of the immobilised enzyme is clearer. Immobilisation of the lipase on a positively charged support shifts its optimum pH to acidic pH by repulsion towards H+ ions around the support. [less ▲]

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