References of "Destain, Jacqueline"
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See detailFormulation solide de la lipase de Yarrowia lipolytica
Alloue, M.; Destain, Jacqueline ULg; Thonart, Philippe ULg

Poster (2005, March 05)

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See detailInvolvement of hexokinase HXK1 in glucose catabolite repression of LIP2 encoding extracellular lipase in the yeast Yarrowia lipolytica
Fickers, Patrick ULg; Nicaud, J. M.; Destain, Jacqueline ULg et al

in Current Microbiology (2005), 50(3), 133-137

The yeast Yarrowia lipolytica produces an extracellular lipase encoded by the LIP2 gene. However, very little is known about the mechanisms controlling its expression, especially on glucose media. In this ... [more ▼]

The yeast Yarrowia lipolytica produces an extracellular lipase encoded by the LIP2 gene. However, very little is known about the mechanisms controlling its expression, especially on glucose media. In this work, the involvement of hexokinase Hxk1 in the glucose catabolite repression of LIP2 was investigated in a lipase overproducing mutant less sensitive to glucose repression. This mutant has a reduced capacity to phosphorylate hexose compared with the wild-type strain, but no differences could be observed between the HXK1 sequences in the two isolates. This suggested that the reduced phosphorylating activity of the mutant strain probably resulted from a modification in the level of HXK1 expression. However, overexpression of the HXK1 gene in this mutant led to a decrease of both LIP2 induction and extracellular lipase activity, suggesting that the hexokinase is involved in the glucose catabolite repression of LIP2 in Y lipolytica. [less ▲]

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See detailSelection of new over-producing derivatives for the improvement of extracellular lipase production by the non-conventional yeast Yarrowia lipolytica
Fickers, Patrick ULg; Fudalej, F.; Nicaud, J. M. et al

in Journal of Biotechnology (2005), 115(4), 379-386

The non-conventional yeast Yarrowia lipolytica produces an extracellular lipase encoded by the LIP2 gene. Mutant strains with enhanced productivity were previously obtained either by chemical mutagenesis ... [more ▼]

The non-conventional yeast Yarrowia lipolytica produces an extracellular lipase encoded by the LIP2 gene. Mutant strains with enhanced productivity were previously obtained either by chemical mutagenesis or genetic engineering. In this work, we used one of these mutants, named LgX64.81 to select new overproducing strains following by amplification of the LIP2 gene. We also developed a process for lipase production in bioreactors and compared lipase production levels in batch and fed-batch cultures. Batch culture led to a lipase production of 26 450 U ml(-1) in a media containing olive oil and tryptone as carbon and nitrogen sources. Feeding of a combination of tryptone and olive oil at the end of the exponential growth phase yielded to lipase activity of 158 246 U ml(-1) after 80 h of cultivation. In addition this production system developed for the extracellular lipase could also be applied for other heterologous protein production since we have demonstrated that LgX64.81 is an interesting alternative host strain. (C) 2004 Elsevier B.V. All rights reserved. [less ▲]

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See detailThe two-phase water/silicon oil bioreactor prospects in off-gas treatment
Aldric, Jean-Marc ULg; Destain, Jacqueline ULg; Thonart, Philippe ULg

in Applied Biochemistry and Biotechnology (2005), 121(Spring), 707-719

Research was carried out to develop a biphasic biologic reactor able to clean the gas effluents polluted by volatile organic compounds. Initially, Rhodococcus erythropolis T 902.1 was selected on the ... [more ▼]

Research was carried out to develop a biphasic biologic reactor able to clean the gas effluents polluted by volatile organic compounds. Initially, Rhodococcus erythropolis T 902.1 was selected on the basis of its capacity to degrade isopropylbenzene (IPB). The effect of gas flow and IPB concentration on the biodegadation of IPB was evaluated. The results show that the use of silicon oil allows large quantities of IPB to be absorbed within the medium of biologic abatement. On the other hand, the biodegradation rate was directly correlated to the inlet flow of IPB. Thus, the reactor presents interesting opportunities for the biologic treatment of gas effluents. [less ▲]

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See detailStudy of catalase production by an Aspergillus phoenicis mutant strain in date flour extract submerged cultures
Kacem-Chaouche, Noreddine; Maraihi; Destain, Jacqueline ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2005), 9(3), 173-178

The production of extracellular catalase in date flour submerged medium by a selected mutant Aspergillus phoenicis K30 (member of the Aspergillus niger group) was investigated. The strain was tested in ... [more ▼]

The production of extracellular catalase in date flour submerged medium by a selected mutant Aspergillus phoenicis K30 (member of the Aspergillus niger group) was investigated. The strain was tested in 500 ml shake-flasks and in a 20 l bioreactor with date powder as a single carbon source. Extracellular catalase production reached 59 U ml-1 in both cases. This value is much greater than that of a wild-type strain (9.5 U ml-1). Microscopic examination showed that the extracellular catalase production was correlated with the ramified hyphals morphology in the external layer of the pellets. [less ▲]

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See detailExpression of a synthetic gene encoding a Tribolium castaneum carboxylesterase in Pichia pastoris
Delroisse, Jean-Marc; Dannau, Marie; Gilsoul, Jean-Jacques et al

in Protein Expression & Purification (2005), 42(2), 286-294

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See detailEstimation of bioreactor efficiency through structured hydrodynamic modeling case study of a Pichia pastoris fed-batch process.
Delvigne, Frank ULg; El Mejdoub, Thami ULg; Destain, Jacqueline ULg et al

in Applied Biochemistry and Biotechnology (2005), 121-124

In this article, two theories are unified to investigate the effect of hydrodynamics on a specific bioprocess: the network-of-zones (NOZ) hydrodynamic structured modeling approach (developed by several ... [more ▼]

In this article, two theories are unified to investigate the effect of hydrodynamics on a specific bioprocess: the network-of-zones (NOZ) hydrodynamic structured modeling approach (developed by several researchers but applied to only a few bioprocesses) and the effectiveness factor eta approach. Two process scales were investigated (20 and 500 L), and for each, hydrodynamics were quantified using an NOZ validated by homogeneity time measurements. Several impeller combinations inducing quite different hydrodynamics were tested at the 20-L scale. After this step, effectiveness factors were determined for each fermentation run. To achieve this, a perfectly mixed microbial kinetic model was evaluated by using simple Monod kinetics with a fed-batch mass balance. This methodology permitted determination of the effectiveness factor with more accuracy because of the relation with the perfect case deduced from the Monod kinetics. It appeared that for the small scale, eta decreased until reaching a value of approx 0.7 (30% from the ideal case) for the three impeller systems investigated. However, stirring systems that include hydrofoils seemed to maintain higher effectiveness factors during the course of the fermentation. This effect can be attributed to oxygen transfer performance or to homogenization efficiency exhibited by the hydrofoils. To distinguish the oxygen transfer from the homogenization component of the effectiveness factor, these phenomena were analyzed separately. After determining the evolution of etaO2 linked to oxygen transfer for each of the fermentation runs, the NOZ model was employed to quantify substrate gradient appearance. After this step, another effectiveness factor, etamix, related to mixing was defined. Consequently, it is possible to distinguish the relative importance of the mixing effect and oxygen transfer on a given bioprocess. The results have highlighted an important scale effect on the bioprocess that can be analyzed using the NOZ model. [less ▲]

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See detailBioreactor hydrodynamic effect on Escherichia coli physiology: experimental results and stochastic simulations.
Delvigne, Frank ULg; Destain, Jacqueline ULg; Thonart, Philippe ULg

in Bioprocess and Biosystems Engineering (2005), 28(2), 131-7

A microorganism circulating in a bioreactor can be submitted to hydrodynamic conditions inducing a significant effect on its physiology. The mixing time exhibited by the stirred bioreactor and the ... [more ▼]

A microorganism circulating in a bioreactor can be submitted to hydrodynamic conditions inducing a significant effect on its physiology. The mixing time exhibited by the stirred bioreactor and the circulation of microorganisms are both involved in this reacting system. The mixing component determines the intensity of the concentration gradient and the circulation component determines the way in which the microorganism is exposed to this gradient. These two components linked to the experimental evaluation of microbial physiology can be analysed by a structured stochastic model in the case of a partitioned or "scale-down" reactor (SDR). A stochastic model indeed enables to simulate the mixing process as well as the circulation of microorganisms in SDRs. The superimposition of mixing and circulation processes determines the concentration profile experienced by a microorganism in the reactor. In the present case, the glucose concentration experienced by Escherichia coli has been modelled during a fed-batch culture. In this context, the use of a stochastic hydrodynamic model has permitted to point out an interesting feed pulse retardant effect in the SDRs. Nevertheless, the metabolic response of E. coli is not easy to interpret because of the possible simultaneous developments of overflow metabolism and mixed acid fermentation induced by the strong glucose concentration in the reactor. [less ▲]

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See detailTraitement biologique d’un effluent de l’industrie des olives
Alloue; Aldric, Jean-Marc ULg; Destain, Jacqueline ULg et al

in Tribune de l'Eau (La) (2005)

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See detailUtilization of methyloleate in production of microbial lipase
Destain, Jacqueline ULg; Fickers, Patrick ULg; Weekers, F. et al

in Applied Biochemistry and Biotechnology (2005), 121(Spring), 269-277

In this article, we report the development and optimization of an industrial culture medium for the production of extracellular lipase in the yeast Yarrowia lipolytica. Until now olive oil in combination ... [more ▼]

In this article, we report the development and optimization of an industrial culture medium for the production of extracellular lipase in the yeast Yarrowia lipolytica. Until now olive oil in combination with glucose was used as the carbon source and inducer for the production of lipase. Our results demonstrate that methyloleate, a cheap hydrophobic compound, could efficiently substitute olive oil as the inducer and carbon source for lipase production. A new process of lipase production was developed yielding a twofold increase in the level of production compared with the levels in previous reports. [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 detailUtilization of methyloleate in the production of Yarrowia lipolytica.
Destain, Jacqueline ULg; Moreau, B.; Weekers, F. et al

Poster (2004, May)

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See detailExtracellular catalase production by Aspergillus phoenicis.
Kacem-Chaouche, N.; Meraihi, Z.; Destain, Jacqueline ULg et al

Poster (2004, May)

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See detailNovel use of lipopeptide preparations
Deleu, Magali ULg; Brans, Alain; Brasseur, Robert ULg et al

Patent (2004)

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See detailCarbon and nitrogen sources modulate lipase production in the yeast Yarrowia lipolytica
Fickers, Patrick ULg; Nicaud, J. M.; Gaillardin, C. et al

in Journal of Applied Microbiology (2004), 96(4), 742-749

AIMS: To analyse the influence of nitrogen and carbon sources on extracellular lipase production by Yarrowia lipolytica-overproducing mutant in order to optimize its production in large-scale bioreactors ... [more ▼]

AIMS: To analyse the influence of nitrogen and carbon sources on extracellular lipase production by Yarrowia lipolytica-overproducing mutant in order to optimize its production in large-scale bioreactors. METHODS AND RESULTS: The level of lipase production and LIP2 induction, measured using an LIP2-LacZ reporter gene, were compared for different carbon and nitrogen sources and for different concentrations. The localization of the enzyme during growth was also determined by Western blotting analysis using a six-histidine-tagged lipase. SIGNIFICANCE AND IMPACT OF THE STUDY: Tryptone N1 and oleic acid are the most suitable nitrogen and carbon sources for the production of the extracellular lipase by the Y. lipolytica mutant. Higher levels of lipase production were obtained as the tryptone concentration increased in the culture medium. Such a positive correlation was not observed with oleic acid media where the highest lipolytic productivities were obtained in the presence of low concentration. We also demonstrate that in the presence of oleic acid, lipase is cell-bound during the growth phase before being released in the media. CONCLUSIONS: This work provides a better understanding of the mechanism controlling LIP2 expression and, thus, extracellular lipase production in the yeast Y. lipolytica. [less ▲]

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See detailOverproduction of lipase by Yarrowia lipolytica mutants
Fickers, Patrick ULg; Nicaud, J. M.; Destain, Jacqueline ULg et al

in Applied Microbiology & Biotechnology (2003), 63(2), 136-142

Non-genetically modified mutants with increased capacities of extracellular lipase production were obtained from Yarrowia lipolytica strain CBS6303 by chemical mutagenesis. Of the 400 mutants isolated ... [more ▼]

Non-genetically modified mutants with increased capacities of extracellular lipase production were obtained from Yarrowia lipolytica strain CBS6303 by chemical mutagenesis. Of the 400 mutants isolated, LgX64.81 had the highest potential for the development of an industrial lipase production process. This mutant exhibits lipase production uncoupled from catabolite repression by glucose, and a 10-fold increased productivity upon addition of oleic acid. Using a LIP2-LacZ reporter gene, we demonstrate that the mutant phenotype originates from a trans-acting mutation. The glucose uptake capacity of LgX64.81 is reduced 2.5-fold compared to the wild-type-strain, and it exhibits high lipase production on glucose medium. A trans-acting mutation in a gene involved in glucose transport could thus explain this mutant phenotype. [less ▲]

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