References of "Ghalfi, Hakim"
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See detailDescription of two Enterococcus strains isolated from traditional Peruvian artisanal-produced cheeses with a bacteriocin-like inhibitory activity
Aguilar Galvez, Ana Consuelo ULg; Dubois Dauphin, Robin ULg; Ghalfi, Hakim et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2009), 13(3), 349-356

The aim of this work was to isolate and to characterize strains of lactic acid bacteria (LAB) with bacteriocin-like inhibitory activity from 27 traditional cheeses artisanal-produced obtained from ... [more ▼]

The aim of this work was to isolate and to characterize strains of lactic acid bacteria (LAB) with bacteriocin-like inhibitory activity from 27 traditional cheeses artisanal-produced obtained from different Peruvian regions. Twenty Gram+ and catalasenegative strains among 2,277 isolates exhibited bacteriocin-like inhibitory activity against Listeria monocytogenes CWBIB2232 as target strain. No change in inhibitory activity was observed after organic acid neutralization and treatment with catalase of the cell-free supernatant (CFS). The proteinic nature of the antimicrobial activity was confirmed for the twenty LAB strains by proteolytic digestion of the CFS. Two strains, CWBI-B1431 and CWBI-B1430, with the best antimicrobial activity were selected for further researches. These strains were taxonomically identified by phenotypic and genotypic analyses as Enterococcus mundtii (CWBI-B1431) and Enterococcus faecium (CWBI-B1430). The two strains were sensitive to vancomycin (MIC < 2 μg.ml-1) and showed absence of haemolysis. [less ▲]

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See detailProduction of γ-Decalactone by a Psychrophilic and a Mesophilic Strain of the Yeast
Alchihab, Mohamed ULg; Destain, Jacqueline ULg; Aguedo, Mario ULg et al

in Applied Biochemistry and Biotechnology (2009), 158

Among 18 psychrophilic strains isolated near the Antarctic Station, the psychrophilic <br />strain Rhodotorula aurantiaca A19 was selected for its ability of growth and γ- <br />decalactone production at ... [more ▼]

Among 18 psychrophilic strains isolated near the Antarctic Station, the psychrophilic <br />strain Rhodotorula aurantiaca A19 was selected for its ability of growth and γ- <br />decalactone production at low temperatures. The effects of temperature, initial pH, and castor <br />oil concentration on the growth and γ-decalactone production by a psychrophilic and a <br />mesophilic strain of R. aurantiaca were investigated. The highest γ-decalactone production <br />in flasks (5.8 g/l) was obtained with the strain A19 at 14 °C and initial pH 7.0 in medium <br />containing 20 g/l castor oil. On the other hand, these factors did not affect the production of <br />γ-decalactone by the mesophilic strain. In fermentor, a γ-decalactone concentration of 6.6 g/l <br />was reached with the strain A19, whereas a maximum of 0.1 g/l was obtained with the <br />mesophilic strain. Our results suggest that the ability to synthesize γ-decalactone is a <br />particularity of the strain A19, since the mesophilic strain (no. 30645) produced small amounts, <br />and the other (no. 31354) did not exhibit this property. It is, to our knowledge, the first report of γ-decalactone production by R. aurantiaca and furthermore by a psychrophilic yeast strain. <br />Moreover, the amount of γ-decalactone obtained in fermentor with the strain 19 was on the <br />order of concentrations usually described in patents. [less ▲]

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See detailImmobilized lipases and their applications
Alloue, Waze Aimee Mireille; Aguedo, Mario ULg; Destain, Jacqueline ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2008), 12(1), 57-68

Lipases are able to catalyse the hydrolysis of glyceridic esters in aqueous media and the synthesis of esters in non-aqueous media. They are thus able to catalyse numerous reactions of industrial interest ... [more ▼]

Lipases are able to catalyse the hydrolysis of glyceridic esters in aqueous media and the synthesis of esters in non-aqueous media. They are thus able to catalyse numerous reactions of industrial interest. Whether it is by inclusion, by adsorption or by covalent link, the immobilisation of lipases aims at conferring them a good stability that enables a reuse of the enzymes after a reaction and the development of continuous processes. The reactions of triglycerides hydrolysis constitute main applications for immobilised lipases, however their use in different types of esterification reactions has also arose: there exist processes involving reactions of transesterification, of interesterification or of esters synthesis. The production of structured lipids by interesterification is one example. Although the reaction conditions dissent from those of hydrolysis, the same lipases have been used in both cases. A lipase specifically adapted for esterification though would be a highly capable tool: a series of strategies is in progress in order to reach this goal. [less ▲]

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See detailComparison of the performances of different fermentation strategies on cell growth and bacteriocin production by Lactobacillus curvatus CWBI-B28
Ghalfi, Hakim; Benkerroum, Noreddine; Doguiet, Dalié et al

in Journal of the Science of Food and Agriculture (2007), 87

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See detailLyophilized Preparations Of Bacteriocinogenic Lactobacillus Curvatus And Lactococcus Lactis Subsp Lactis As Potential Protective Adjuncts To Control Listeria Monocytogenes In Dry-Fermented Sausages
Benkerroum, N.; Daoudi, A.; Hamraoui, T. et al

in Journal of Applied Microbiology (2005), 98(1),

Methyl oleate was used as a primary carbon source and as an alternative inducer for the production of an extracellular lipase, Lip2, in Y. lipol.vtica strain LgX64.81 grown in a 20-1 bioreactor. The ... [more ▼]

Methyl oleate was used as a primary carbon source and as an alternative inducer for the production of an extracellular lipase, Lip2, in Y. lipol.vtica strain LgX64.81 grown in a 20-1 bioreactor. The lipase-encoding gene, LIP2, was investigated during culture on methyl oleate using a pLIP2-LacZ reporter fusion and we provide evidence for the involvement of methyl oleate in its regulation. [less ▲]

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