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Auteur Karima Kharroub |
Documents disponibles écrits par cet auteur (9)
Affiner la recherche Interroger des sources externesCaractérisation des bactéries lactiques autochtones productrices d’exopolysaccharides et étude de leurs effets intrinsèques sur une matrice laitière. / Nadia Benhedane née Bachtarzi
Titre : Caractérisation des bactéries lactiques autochtones productrices d’exopolysaccharides et étude de leurs effets intrinsèques sur une matrice laitière. Type de document : texte imprimé Auteurs : Nadia Benhedane née Bachtarzi, Auteur ; Karima Kharroub, Directeur de thèse ; Patricia Ruas-Madiedo, Directeur de thèse Mention d'édition : 02/11/2020 Editeur : جامعة الإخوة منتوري قسنطينة Année de publication : 2020 Importance : 226 f. Format : 30 cm. Note générale : 1 copies imprimées disponibles
Langues : Français (fre) Catégories : Français - Anglais
Nutrition, Alimentation et Technologies Agro-AlimentairesTags : Biotechnologie: Sciences Alimentaires fermented dairy products lactic acid bacteria exopolysaccharides structure viscosity produits laitiers fermentés bactéries lactiques viscosité منتجات الألبان المخمرة بكتيريا حمض اللاكتيك السكريات الخارجية البنية اللزوجة Index. décimale : 640 Industrie Alimentaire Résumé :
The naturally fermented dairy products are an interesting source of new strains of lactic acid bacteria (LAB) with proven technological potential. Some of them are capable of synthesizing exopolysaccharides (EPS) during fermentation, which improve the rheological properties of dairy matrices. This thesis work focuses on the selection of LAB producing EPS from local fermented dairy products. A total of 30 samples were collected in Eastern Algeria, from which 584 presumptive isolates of LAB were tested for the production of EPS. Only 18 isolates presented a productive phenotype, their polyphasic characterization confirmed that they belong to two species: Leuconostoc mesenteroides and Lactobacillus plantarum. A preselection based on the stability of EPS production character made it possible to retain 6 strains in addition to a control strain, all affiliated to the Lactobacillus plantarum species. Then macroscopic characterization of their lactic gels allowed to select two strains LBIO1 and LBIO28 producing viscosifying EPS in a dairy matrix. The study of their production revealed that the polymers produced are primary metabolites, with a high molecular weight. In parallel, a characterization of the macro and microstructure under confocal laser scanning microscopy of the two gels SMCLBIO1 and SMCLBIO28, compared to the control gel SMCLBIO14, concluded that the EPS of the two ropy strains contribute significantly to the improvement of the physical attributes of lactic gels. Furthermore, micrographs made by cryo-electron microscopy showed the existence of a dense web-like EPS attached to the cells for both ropy strains, which is not observed for LBIO14. Finally, a complete sequencing of the three genomes followed by an in silico genomic analysis confirmed the safety of the strains and the existence of genes coding for bacteriocins and vitamins. The study of the biosynthetic machinery of EPS in comparison with the reference strain Lactobacillus plantarum WCF1 revealed the presence of 2 complete eps clusters cps3 and cps4 in the three genomes with 100% similarity between them, all chromosomal. However, the two strains LBIO1 and LBIO28 have in addition genes belonging to cps2, which would therefore be involved in the synthesis of the ropy polymer with high molecular weight. The two ropy strains LBIO1 and LBIO28 can therefore be exploited in dairy fermentation, based on the techno-functional properties of their polymers, which contribute to the improvement of the rheological characteristics of the matrices generated.
Diplôme : Doctorat en sciences En ligne : ../theses/agronomie/BAC7671.pdf Format de la ressource électronique : Permalink : index.php?lvl=notice_display&id=11505 Caractérisation des bactéries lactiques autochtones productrices d’exopolysaccharides et étude de leurs effets intrinsèques sur une matrice laitière. [texte imprimé] / Nadia Benhedane née Bachtarzi, Auteur ; Karima Kharroub, Directeur de thèse ; Patricia Ruas-Madiedo, Directeur de thèse . - 02/11/2020 . - جامعة الإخوة منتوري قسنطينة, 2020 . - 226 f. ; 30 cm.
1 copies imprimées disponibles
Langues : Français (fre)
Catégories : Français - Anglais
Nutrition, Alimentation et Technologies Agro-AlimentairesTags : Biotechnologie: Sciences Alimentaires fermented dairy products lactic acid bacteria exopolysaccharides structure viscosity produits laitiers fermentés bactéries lactiques viscosité منتجات الألبان المخمرة بكتيريا حمض اللاكتيك السكريات الخارجية البنية اللزوجة Index. décimale : 640 Industrie Alimentaire Résumé :
The naturally fermented dairy products are an interesting source of new strains of lactic acid bacteria (LAB) with proven technological potential. Some of them are capable of synthesizing exopolysaccharides (EPS) during fermentation, which improve the rheological properties of dairy matrices. This thesis work focuses on the selection of LAB producing EPS from local fermented dairy products. A total of 30 samples were collected in Eastern Algeria, from which 584 presumptive isolates of LAB were tested for the production of EPS. Only 18 isolates presented a productive phenotype, their polyphasic characterization confirmed that they belong to two species: Leuconostoc mesenteroides and Lactobacillus plantarum. A preselection based on the stability of EPS production character made it possible to retain 6 strains in addition to a control strain, all affiliated to the Lactobacillus plantarum species. Then macroscopic characterization of their lactic gels allowed to select two strains LBIO1 and LBIO28 producing viscosifying EPS in a dairy matrix. The study of their production revealed that the polymers produced are primary metabolites, with a high molecular weight. In parallel, a characterization of the macro and microstructure under confocal laser scanning microscopy of the two gels SMCLBIO1 and SMCLBIO28, compared to the control gel SMCLBIO14, concluded that the EPS of the two ropy strains contribute significantly to the improvement of the physical attributes of lactic gels. Furthermore, micrographs made by cryo-electron microscopy showed the existence of a dense web-like EPS attached to the cells for both ropy strains, which is not observed for LBIO14. Finally, a complete sequencing of the three genomes followed by an in silico genomic analysis confirmed the safety of the strains and the existence of genes coding for bacteriocins and vitamins. The study of the biosynthetic machinery of EPS in comparison with the reference strain Lactobacillus plantarum WCF1 revealed the presence of 2 complete eps clusters cps3 and cps4 in the three genomes with 100% similarity between them, all chromosomal. However, the two strains LBIO1 and LBIO28 have in addition genes belonging to cps2, which would therefore be involved in the synthesis of the ropy polymer with high molecular weight. The two ropy strains LBIO1 and LBIO28 can therefore be exploited in dairy fermentation, based on the techno-functional properties of their polymers, which contribute to the improvement of the rheological characteristics of the matrices generated.
Diplôme : Doctorat en sciences En ligne : ../theses/agronomie/BAC7671.pdf Format de la ressource électronique : Permalink : index.php?lvl=notice_display&id=11505 Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité BAC/7671 BAC/7671 Thèse Bibliothèque principale Thèses Disponible
Titre : Caractérisation des bactéries lactiques isolées du beurre cru, évaluation de leurs aptitudes technologiques et leur utilisation dans la fabrication de la crème sure Type de document : texte imprimé Auteurs : Bilal Latreche, Auteur ; Karima Kharroub, Directeur de thèse Editeur : جامعة الإخوة منتوري قسنطينة Année de publication : 2015 Importance : 130 f. Format : 30 cm. Note générale : 2 copies imprimes disponibles Langues : Français (fre) Catégories : Français - Anglais
Nutrition, Alimentation et Technologies Agro-AlimentairesTags : Technologie alimentaire Bactérie lactique beurre cru ferments mixtes aptitudes technologiques crème sure lactic acid bacteria raw butter mixed starters technological ability sour cream البكتریا اللبنية زبدة البقر خميرة لبنية القابلية التكنولوجية قشدة الحليب الحامضة Index. décimale : 640 Industrie Alimentaire Résumé : Dairy products are considered to be a good source of lactic acid bacteria. Currently in
Algeria, indigenous lactic flora of local traditional products has given a considerable interest.
Thirty lactic acid bacteria were isolated, purified and characterized from traditionally
manufactured raw butter in laboratory using cow's milk from El-Eulma municipality (wilaya
of Setif). These strains belong to five genera: Enterococcus (40%), Lactococcus (17%),
Streptococcus (17%), Leuconostoc (13%), and Lactobacillus (13%). characterization with
biochemical Gallery API 50 CH has classified the strains within the following species:
Leuconostoc mesenteroides ssp. Mesenteroides, Lactococcus lactis ssp. Diacetylactis,
Leuconostoc lactis, Lactobacillus delbrueckii ssp. Lactis and Lactococcus lactis ssp. Lactis.
The results of the evaluation of the technological ability of pure cultures and mixed starters
demonstrate a good proteolytic activity, flavouring, texturizing, and antibacterial.
The application of reconstituted mixed starters in sour cream manufacturing revealed a better
hygienic quality that meets national and international standards.
Diplôme : Magistère En ligne : ../theses/agronomie/LAT6830.pdf Format de la ressource électronique : Permalink : index.php?lvl=notice_display&id=10122 Caractérisation des bactéries lactiques isolées du beurre cru, évaluation de leurs aptitudes technologiques et leur utilisation dans la fabrication de la crème sure [texte imprimé] / Bilal Latreche, Auteur ; Karima Kharroub, Directeur de thèse . - جامعة الإخوة منتوري قسنطينة, 2015 . - 130 f. ; 30 cm.
2 copies imprimes disponibles
Langues : Français (fre)
Catégories : Français - Anglais
Nutrition, Alimentation et Technologies Agro-AlimentairesTags : Technologie alimentaire Bactérie lactique beurre cru ferments mixtes aptitudes technologiques crème sure lactic acid bacteria raw butter mixed starters technological ability sour cream البكتریا اللبنية زبدة البقر خميرة لبنية القابلية التكنولوجية قشدة الحليب الحامضة Index. décimale : 640 Industrie Alimentaire Résumé : Dairy products are considered to be a good source of lactic acid bacteria. Currently in
Algeria, indigenous lactic flora of local traditional products has given a considerable interest.
Thirty lactic acid bacteria were isolated, purified and characterized from traditionally
manufactured raw butter in laboratory using cow's milk from El-Eulma municipality (wilaya
of Setif). These strains belong to five genera: Enterococcus (40%), Lactococcus (17%),
Streptococcus (17%), Leuconostoc (13%), and Lactobacillus (13%). characterization with
biochemical Gallery API 50 CH has classified the strains within the following species:
Leuconostoc mesenteroides ssp. Mesenteroides, Lactococcus lactis ssp. Diacetylactis,
Leuconostoc lactis, Lactobacillus delbrueckii ssp. Lactis and Lactococcus lactis ssp. Lactis.
The results of the evaluation of the technological ability of pure cultures and mixed starters
demonstrate a good proteolytic activity, flavouring, texturizing, and antibacterial.
The application of reconstituted mixed starters in sour cream manufacturing revealed a better
hygienic quality that meets national and international standards.
Diplôme : Magistère En ligne : ../theses/agronomie/LAT6830.pdf Format de la ressource électronique : Permalink : index.php?lvl=notice_display&id=10122 Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité LAT/6830 LAT/6830 Thèse Bibliothèque principale Thèses Disponible
Titre : Caractérisation de souches de Streptococcus thermophilus et Streptococcus macedonicus dans des laits fermentés traditionnels algériens : Etude de quelques pré-requis au potentiel probiotique. Type de document : texte imprimé Auteurs : Tedj El Moulouk Khaldi, Auteur ; Karima Kharroub, Directeur de thèse ; Emeline Roux, Directeur de thèse Mention d'édition : 29 juin 2020 Editeur : جامعة الإخوة منتوري قسنطينة Année de publication : 2020 Importance : 191 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles
Langues : Français (fre) Catégories : Français - Anglais
Nutrition, Alimentation et Technologies Agro-AlimentairesTags : Streptococcus macedonicus Streptococcus thermophilus laits fermentés traditionnels Caco-2 TC7 HT29-MTX HT29-CL16E Traditional fermented milks ستريبتوكوكوس ماسيدونيكوس ستريبتوكوكوس ثيرموفيلوس مشتقات الحليب التقليدية Index. décimale : 640 Industrie Alimentaire Résumé :
The aim of this work is to select a set of new strains of non-pathogenic thermophilic streptococci namely S. thermophilus and S. macedonicus from traditional Algerian fermented milk samples (lben and rayeb) and to characterize some properties prior to a probiotic effect (abilities to resist environments simulating the conditions of the gastrointestinal tract [GIT] and to adhere to intestinal epithelial cells in vitro).
The methodology adopted in this work consists of phenotypic (growth in Bile Esculin Azide, 6.5% w/v NaCl, pH 9.6) and genotypic identification (sequencing of 16S rRNA, STIs and RAPD and MLST techniques) of the isolates from lben and rayeb, as well as an assessment of their acidification capacity, thus allowing a first characterization of the strains. Then, in a second step, the selected strains are studied for their ability to survive for 2 hours at low pH values and at different concentrations of an equimolar mixture of bile salts (MBS). Three cellular models Caco-2 TC7, HT29-MTX and HT29-CL16E were used for the study of adhesion. Results were obtained from four strains of S. macedonicus genetically distinct from the reference strain S. macedonicus ACA-DC-198 and from one strain of S. thermophilus also different from the strain S. thermophilus LMD-9. These strains are capable of surviving down to pH 3 and tolerate high concentrations of bile salts (10 mM) in opposition to reference strains Streptococcus thermophilus LMD-9 and Lactobacillus rhamnosus GG. In addition, the studied strains have adhesion ability similar to that of Lactobacillus rhamnosus GG on Caco-2 TC7. on the other hand, strains S. macedonicus PA and S. thermophilus LF9 have good adhesion qualities to HT29-MTX and HT29-CL16E mucus cells. This first characterization makes it possible to consider the strains of S. macedonicus and Streptococcus thermophilus as potential candidates for prospective probiotic effects which deserve to be studied further more.
Note de contenu : Annexes. Diplôme : Doctorat en sciences En ligne : ../theses/agronomie/KHA7619.pdf Format de la ressource électronique : Permalink : index.php?lvl=notice_display&id=11455 Caractérisation de souches de Streptococcus thermophilus et Streptococcus macedonicus dans des laits fermentés traditionnels algériens : Etude de quelques pré-requis au potentiel probiotique. [texte imprimé] / Tedj El Moulouk Khaldi, Auteur ; Karima Kharroub, Directeur de thèse ; Emeline Roux, Directeur de thèse . - 29 juin 2020 . - جامعة الإخوة منتوري قسنطينة, 2020 . - 191 f. ; 30 cm.
2 copies imprimées disponibles
Langues : Français (fre)
Catégories : Français - Anglais
Nutrition, Alimentation et Technologies Agro-AlimentairesTags : Streptococcus macedonicus Streptococcus thermophilus laits fermentés traditionnels Caco-2 TC7 HT29-MTX HT29-CL16E Traditional fermented milks ستريبتوكوكوس ماسيدونيكوس ستريبتوكوكوس ثيرموفيلوس مشتقات الحليب التقليدية Index. décimale : 640 Industrie Alimentaire Résumé :
The aim of this work is to select a set of new strains of non-pathogenic thermophilic streptococci namely S. thermophilus and S. macedonicus from traditional Algerian fermented milk samples (lben and rayeb) and to characterize some properties prior to a probiotic effect (abilities to resist environments simulating the conditions of the gastrointestinal tract [GIT] and to adhere to intestinal epithelial cells in vitro).
The methodology adopted in this work consists of phenotypic (growth in Bile Esculin Azide, 6.5% w/v NaCl, pH 9.6) and genotypic identification (sequencing of 16S rRNA, STIs and RAPD and MLST techniques) of the isolates from lben and rayeb, as well as an assessment of their acidification capacity, thus allowing a first characterization of the strains. Then, in a second step, the selected strains are studied for their ability to survive for 2 hours at low pH values and at different concentrations of an equimolar mixture of bile salts (MBS). Three cellular models Caco-2 TC7, HT29-MTX and HT29-CL16E were used for the study of adhesion. Results were obtained from four strains of S. macedonicus genetically distinct from the reference strain S. macedonicus ACA-DC-198 and from one strain of S. thermophilus also different from the strain S. thermophilus LMD-9. These strains are capable of surviving down to pH 3 and tolerate high concentrations of bile salts (10 mM) in opposition to reference strains Streptococcus thermophilus LMD-9 and Lactobacillus rhamnosus GG. In addition, the studied strains have adhesion ability similar to that of Lactobacillus rhamnosus GG on Caco-2 TC7. on the other hand, strains S. macedonicus PA and S. thermophilus LF9 have good adhesion qualities to HT29-MTX and HT29-CL16E mucus cells. This first characterization makes it possible to consider the strains of S. macedonicus and Streptococcus thermophilus as potential candidates for prospective probiotic effects which deserve to be studied further more.
Note de contenu : Annexes. Diplôme : Doctorat en sciences En ligne : ../theses/agronomie/KHA7619.pdf Format de la ressource électronique : Permalink : index.php?lvl=notice_display&id=11455 Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité KHA/7619 KHA/7619 Thèse Bibliothèque principale Thèses Disponible
Titre : Contribution à l'étude de la diversité des bactéries thermophiles de quelques environnements chauds algériens et essai de de production et de caractérisation de leurs protéases extracellulaires. Type de document : texte imprimé Auteurs : Mohamed Amine Gomri, Auteur ; Karima Kharroub, Directeur de thèse Editeur : جامعة الإخوة منتوري قسنطينة Année de publication : 2019 Importance : 308 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles
Langues : Français (fre) Catégories : Français - Anglais
Nutrition, Alimentation et Technologies Agro-AlimentairesTags : Biotechnologie:Sciences Alimentaires environnements chauds algériens diversité bactéries thermophiles protéases extracellulaires Algerian hot environments diversity bacteria thermophilic extracellular
proteases بينات ساخنة جزائرية تنوع-بكتيريا محبة للحرارة بروتياز خارج الخليةIndex. décimale : 640 Industrie Alimentaire Résumé :
Natural hot environments can represent an important source of microbial biodiversity and biomolecules with great added value. Among these biomolecules, extracellular hydrolases and in particular proteases are of great interest for the food industry because of their single reactional properties at high temperatures and their stability in various environmental conditions. The primary objective of this thesis is the isolation of thermophilic aerobic bacteria with extracellular proteolytic activities from 7 sites representing different Algerian hot environments: three geothermal sources, two Saharan soils, a sebkha and an oil field. On the
138 isolates selected on the basis of their macroscopic and microscopic morphological characters, 53 isolates able to degrade casein and/or gelatin on solid culture media were characterized by amplified ribosomal DNA restriction analysis. After the elimination of clones, 28 strains were identified by sequencing and analyzing their 16S rRNA genes. These strains belong to 5 genera of aerobic thermophilic endospore-forming bacteria: Anoxybacillus, Bacillus, Geobacillus, Brevibacillus and Thermoactinomyces. The physiological and biochemical characterization of these strains confirm the relationship with these genera. The genomes of two strains, Geobacillus Sah69 and Thermoactinomyces AS95, were then characterized. The production of putative extracellular proteases of industrial interest was revealed. In addition, the biodiversity of the geothermal sources of Debagh and Ouled Ali was studied by metagenomic analysis of the 16S rRNA hypervariable V4 region sequences of environmental DNA collected from sediment samples. The thermophilic aerobic bacterial communities dominate the two sites with a minor presence of the phylum of Firmicutes and the genera isolated by cultural methods. Lastly, the production of extracellular proteases was estimated quantitatively for the 28 selected strains. Study of production kinetics and effect of fermentation conditions on three selected strains, Geobacillus Sah69, Thermoactinomyces AS95 and Brevibacillus OA30, were then carried out. After the extraction of the supernatant, two proteases, metalloprotease 32- F38 and serine-protease 16-F39, were produced and purified from strain Brevibacillus OA30. These proteases were acid, thermoactive and had a great stability in presence of SDS, solvents and other chemical agents tested. Thus revealing a good potential for industrial application.Note de contenu :
Annexes.Diplôme : Doctorat en sciences En ligne : ../theses/agronomie/GOM7444.pdf Format de la ressource électronique : Permalink : index.php?lvl=notice_display&id=11222 Contribution à l'étude de la diversité des bactéries thermophiles de quelques environnements chauds algériens et essai de de production et de caractérisation de leurs protéases extracellulaires. [texte imprimé] / Mohamed Amine Gomri, Auteur ; Karima Kharroub, Directeur de thèse . - جامعة الإخوة منتوري قسنطينة, 2019 . - 308 f. ; 30 cm.
2 copies imprimées disponibles
Langues : Français (fre)
Catégories : Français - Anglais
Nutrition, Alimentation et Technologies Agro-AlimentairesTags : Biotechnologie:Sciences Alimentaires environnements chauds algériens diversité bactéries thermophiles protéases extracellulaires Algerian hot environments diversity bacteria thermophilic extracellular
proteases بينات ساخنة جزائرية تنوع-بكتيريا محبة للحرارة بروتياز خارج الخليةIndex. décimale : 640 Industrie Alimentaire Résumé :
Natural hot environments can represent an important source of microbial biodiversity and biomolecules with great added value. Among these biomolecules, extracellular hydrolases and in particular proteases are of great interest for the food industry because of their single reactional properties at high temperatures and their stability in various environmental conditions. The primary objective of this thesis is the isolation of thermophilic aerobic bacteria with extracellular proteolytic activities from 7 sites representing different Algerian hot environments: three geothermal sources, two Saharan soils, a sebkha and an oil field. On the
138 isolates selected on the basis of their macroscopic and microscopic morphological characters, 53 isolates able to degrade casein and/or gelatin on solid culture media were characterized by amplified ribosomal DNA restriction analysis. After the elimination of clones, 28 strains were identified by sequencing and analyzing their 16S rRNA genes. These strains belong to 5 genera of aerobic thermophilic endospore-forming bacteria: Anoxybacillus, Bacillus, Geobacillus, Brevibacillus and Thermoactinomyces. The physiological and biochemical characterization of these strains confirm the relationship with these genera. The genomes of two strains, Geobacillus Sah69 and Thermoactinomyces AS95, were then characterized. The production of putative extracellular proteases of industrial interest was revealed. In addition, the biodiversity of the geothermal sources of Debagh and Ouled Ali was studied by metagenomic analysis of the 16S rRNA hypervariable V4 region sequences of environmental DNA collected from sediment samples. The thermophilic aerobic bacterial communities dominate the two sites with a minor presence of the phylum of Firmicutes and the genera isolated by cultural methods. Lastly, the production of extracellular proteases was estimated quantitatively for the 28 selected strains. Study of production kinetics and effect of fermentation conditions on three selected strains, Geobacillus Sah69, Thermoactinomyces AS95 and Brevibacillus OA30, were then carried out. After the extraction of the supernatant, two proteases, metalloprotease 32- F38 and serine-protease 16-F39, were produced and purified from strain Brevibacillus OA30. These proteases were acid, thermoactive and had a great stability in presence of SDS, solvents and other chemical agents tested. Thus revealing a good potential for industrial application.Note de contenu :
Annexes.Diplôme : Doctorat en sciences En ligne : ../theses/agronomie/GOM7444.pdf Format de la ressource électronique : Permalink : index.php?lvl=notice_display&id=11222 Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité GOM/7444 GOM/7444 Thèse Bibliothèque principale Thèses Disponible
Titre : Étude des Archaea halophiles extrêmes isolées d’environnements hypersalins algériens et caractérisation de leurs caroténoïdes. Type de document : texte imprimé Auteurs : Kaouther Sahli, Auteur ; Karima Kharroub, Directeur de thèse ; Mohamed Amine Gomri, Directeur de thèse Mention d'édition : 05/01/2021 Editeur : جامعة الإخوة منتوري قسنطينة Année de publication : 2021 Importance : 214 f. Format : 30 cm. Note générale : Doctorat 3éme CYCLE LMD.
1 copies imprimées disponibles
Langues : Français (fre) Catégories : Français - Anglais
Nutrition, Alimentation et Technologies Agro-AlimentairesTags : INATAA: Biotechnologie Archaea halophiles extrêmes environnements hypersalins Algérie caroténoïdes caractérisation Extremely halophilic Archaea hypersaline environments Algeria carotenoids characterization العَتَائق المحبة للملوحة البيئَات شَديدَة الملوحة الجزائر الكاروتينات وصف Index. décimale : 640 Industrie Alimentaire Résumé :
Hypersaline lakes constitute a typical example of extreme environments harboring a particular microbial flora, which defies the laws of biology and thrives at the limits of life. Extremely halophilic archaea or haloarchaea dominate the microbial communities found in these environments. These microorganisms represent a deposit of natural resources in biomolecules of industrial interest, in particular pigments. The main objective of this thesis is to isolate extremely halophilic, pigment producers archaeal strains from brine and salt samples collected from 7 different Algerian hypersaline environments. In total, 110 isolates were selected on the basis of their macroscopic morphological characters. Of this total, 43 isolates producing high levels of carotenoids and/or showing highest growth in wide salinity, temperature and pH ranges were selected for phenotypic and molecular characterization. 16S rRNA genes sequencing and analysis revealed that theses strains belong to 7 different archaeal genera of the class Halobaceria: Halorubrum, Haloracula, Haloferax, Natrinema, Halogeometricum, Haloterrigena and Halopiger. Strains Halorubrum sp. BS2 ; Halogeometricum sp. ME3 ; Haloarcula sp. BT9 and Haloferax sp. ME16 were then selected for the study of their carotenoids. Chromatographic and spectrometric analysis of carotenoid extracts revealed a variation in the composition depending on the strain with a predominance of bacterioruberin. The evaluation of antioxidant capacity using in vitro ABTS and DPPH assays showed that these extracts have a strong antioxidant potential, in particular those of Halorubrum sp. BS2 and Haloferax sp. ME16 strains, revealing thus a good potential for biotechnological applications. Antibacterial activity of carotenoid extracts against 4 human‐pathogenic strains and 4 fish pathogenic strains was also evaluated by agar disk diffusion method. The obtained results showed a good antibacterial activity. Lastly, the strain Halorubrum sp. BS2 which showed the highest carotenoid content and interesting biological activities was selected to study the effect of the variation in cultural conditions on its growth and carotenoid production. The results showed that the highest growth and carotenoid contents were obtained at a salinity of 25 % (w/v), under an agitation speed of 300 tpm, at a temperature of 37°C and with a light intensity of 260 µE m-2 s-1.Note de contenu :
Annexes.Diplôme : Doctorat En ligne : ../theses/agronomie/SAH7697.pdf Format de la ressource électronique : Permalink : index.php?lvl=notice_display&id=11531 Étude des Archaea halophiles extrêmes isolées d’environnements hypersalins algériens et caractérisation de leurs caroténoïdes. [texte imprimé] / Kaouther Sahli, Auteur ; Karima Kharroub, Directeur de thèse ; Mohamed Amine Gomri, Directeur de thèse . - 05/01/2021 . - جامعة الإخوة منتوري قسنطينة, 2021 . - 214 f. ; 30 cm.
Doctorat 3éme CYCLE LMD.
1 copies imprimées disponibles
Langues : Français (fre)
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Nutrition, Alimentation et Technologies Agro-AlimentairesTags : INATAA: Biotechnologie Archaea halophiles extrêmes environnements hypersalins Algérie caroténoïdes caractérisation Extremely halophilic Archaea hypersaline environments Algeria carotenoids characterization العَتَائق المحبة للملوحة البيئَات شَديدَة الملوحة الجزائر الكاروتينات وصف Index. décimale : 640 Industrie Alimentaire Résumé :
Hypersaline lakes constitute a typical example of extreme environments harboring a particular microbial flora, which defies the laws of biology and thrives at the limits of life. Extremely halophilic archaea or haloarchaea dominate the microbial communities found in these environments. These microorganisms represent a deposit of natural resources in biomolecules of industrial interest, in particular pigments. The main objective of this thesis is to isolate extremely halophilic, pigment producers archaeal strains from brine and salt samples collected from 7 different Algerian hypersaline environments. In total, 110 isolates were selected on the basis of their macroscopic morphological characters. Of this total, 43 isolates producing high levels of carotenoids and/or showing highest growth in wide salinity, temperature and pH ranges were selected for phenotypic and molecular characterization. 16S rRNA genes sequencing and analysis revealed that theses strains belong to 7 different archaeal genera of the class Halobaceria: Halorubrum, Haloracula, Haloferax, Natrinema, Halogeometricum, Haloterrigena and Halopiger. Strains Halorubrum sp. BS2 ; Halogeometricum sp. ME3 ; Haloarcula sp. BT9 and Haloferax sp. ME16 were then selected for the study of their carotenoids. Chromatographic and spectrometric analysis of carotenoid extracts revealed a variation in the composition depending on the strain with a predominance of bacterioruberin. The evaluation of antioxidant capacity using in vitro ABTS and DPPH assays showed that these extracts have a strong antioxidant potential, in particular those of Halorubrum sp. BS2 and Haloferax sp. ME16 strains, revealing thus a good potential for biotechnological applications. Antibacterial activity of carotenoid extracts against 4 human‐pathogenic strains and 4 fish pathogenic strains was also evaluated by agar disk diffusion method. The obtained results showed a good antibacterial activity. Lastly, the strain Halorubrum sp. BS2 which showed the highest carotenoid content and interesting biological activities was selected to study the effect of the variation in cultural conditions on its growth and carotenoid production. The results showed that the highest growth and carotenoid contents were obtained at a salinity of 25 % (w/v), under an agitation speed of 300 tpm, at a temperature of 37°C and with a light intensity of 260 µE m-2 s-1.Note de contenu :
Annexes.Diplôme : Doctorat En ligne : ../theses/agronomie/SAH7697.pdf Format de la ressource électronique : Permalink : index.php?lvl=notice_display&id=11531 Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité SAH/7697 SAH/7697 Thèse Bibliothèque principale Thèses Disponible
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