Résultat de la recherche
2 résultat(s) recherche sur le tag 'biocontrôle' 
Affiner la recherche Générer le flux rss de la recherche
Partager le résultat de cette recherche Interroger des sources externes
Titre : Activité Killer chez des levures isolées des sols du Nord-Est Algérien : Purification, caractérisation et effet sur les souches de levures indésirables. Type de document : texte imprimé Auteurs : Fatima-Zohra-Kenza Labbani, Auteur ; Zahia Meraihi, Directeur de thèse Editeur : جامعة الإخوة منتوري قسنطينة Année de publication : 2015 Importance : 103 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles
Langues : Français (fre) Catégories : Français - Anglais
BiologieTags : levures isolement Pichia kluyveri toxine killer biocontrôle levures indésirables Yeast isolation killer toxin biocontrol undesirable yeasts ????? ??? ?? ???? ?????? ????? ????? ??? ????? ???? Index. décimale : 570 Sciences de la vie. Biologie Résumé : The general purpose of this thesis is to search for killer activity in yeast strains isolated from agricultural and forest soil in the region of Constantine for biotechnological applications.The isolation of yeasts allows to list 15 strains. The molecular taxonomy based on the sequences of D1/D2 domain of the 26S ribosomal ARN gene groups these isolates into 6 different species: Cryptococcus aerius, Hanseniaspora opuntiae, Hanseniaspora uvarum, Pichia kluyveri, Meyerozyma guilliermondii and Saccharomyces cerevisiae. Morphological, physiological and biochemical characteristics of the strains are in agreement with those cited in
literature. Preliminary testing for killer activity reveals that only the strain L5 is able to produce killer activity. The killer strain is belonging to the species P. kluyveri. The crude killer protein produced by the strain P. kluyveri reveals that the toxin is active against food and beverage spoilage yeast strains belonging to the genera: Dekkera, Kluyveromyces, Pichia, Saccharomyces, Torulaspora, Wickerhamomyces and Zygosaccharomyces. The highest killer activity is obtained against the strain Dekkera bruxellensis DBVPG 6706. Both the heat shock (30 min at 100°C) and the enzymatic treatment with pronase demonstrate the complete loss of the initial killer activity of the toxin, and hence its proteinaceous nature is apparently confirmed. The active protein migrates as a single band in SDS-PAGE and has a molecular mass of 54 kDa. The purified killer toxin has an optimal pH between 4.0-4.5, while the optimal of temperature is 25°C.The determination of minimum inhibitory concentrations (MICs) shows that the purified killer protein has a high in vitro activity against D.bruxellensis (MICs from 64 000- to 256 000-fold lower than that exhibited by potassium metabisulphite) and Saccharomyces cerevisiae (MICs from 32 000- to 64 000-fold lower than potassium sorbate).
No in vitro synergistic interactions (calculated by FIC index -Σ FIC) are observed when killer protein is used in combination with the active compounds : potassium metabisulphite, potassium sorbate, or ethanol. The killer protein exhibited a dose–response effect against D.
bruxellensis and S. cerevisiae in a soft drink « Campari MIXX » (Milan, Italy) and pear juice « Santal » (Parma, Italy), respectively. The results of the present study suggest that the killer protein could be proposed as a novel food-grade compound useful for the control of food and beverage spoilage yeasts. Additionally, the purified killer protein maintains its killing action at
least for 3 days against S. cerevisiae DBVPG 6500 inoculated in pear juice and for 10 days against D. bruxellensis DBVPG 6706 in soft drink. The results of the present study suggest that the killer protein produced by the strain P. kluyveri (L5) could be proposed as a novel natural agent for the biocontrole of beverage spoilage yeasts.
Diplôme : Doctorat En ligne : ../theses/biologie/LAB6794.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10026 Activité Killer chez des levures isolées des sols du Nord-Est Algérien : Purification, caractérisation et effet sur les souches de levures indésirables. [texte imprimé] / Fatima-Zohra-Kenza Labbani, Auteur ; Zahia Meraihi, Directeur de thèse . - [S.l.] : جامعة الإخوة منتوري قسنطينة, 2015 . - 103 f. ; 30 cm.
2 copies imprimées disponibles
Langues : Français (fre)
Catégories : Français - Anglais
BiologieTags : levures isolement Pichia kluyveri toxine killer biocontrôle levures indésirables Yeast isolation killer toxin biocontrol undesirable yeasts ????? ??? ?? ???? ?????? ????? ????? ??? ????? ???? Index. décimale : 570 Sciences de la vie. Biologie Résumé : The general purpose of this thesis is to search for killer activity in yeast strains isolated from agricultural and forest soil in the region of Constantine for biotechnological applications.The isolation of yeasts allows to list 15 strains. The molecular taxonomy based on the sequences of D1/D2 domain of the 26S ribosomal ARN gene groups these isolates into 6 different species: Cryptococcus aerius, Hanseniaspora opuntiae, Hanseniaspora uvarum, Pichia kluyveri, Meyerozyma guilliermondii and Saccharomyces cerevisiae. Morphological, physiological and biochemical characteristics of the strains are in agreement with those cited in
literature. Preliminary testing for killer activity reveals that only the strain L5 is able to produce killer activity. The killer strain is belonging to the species P. kluyveri. The crude killer protein produced by the strain P. kluyveri reveals that the toxin is active against food and beverage spoilage yeast strains belonging to the genera: Dekkera, Kluyveromyces, Pichia, Saccharomyces, Torulaspora, Wickerhamomyces and Zygosaccharomyces. The highest killer activity is obtained against the strain Dekkera bruxellensis DBVPG 6706. Both the heat shock (30 min at 100°C) and the enzymatic treatment with pronase demonstrate the complete loss of the initial killer activity of the toxin, and hence its proteinaceous nature is apparently confirmed. The active protein migrates as a single band in SDS-PAGE and has a molecular mass of 54 kDa. The purified killer toxin has an optimal pH between 4.0-4.5, while the optimal of temperature is 25°C.The determination of minimum inhibitory concentrations (MICs) shows that the purified killer protein has a high in vitro activity against D.bruxellensis (MICs from 64 000- to 256 000-fold lower than that exhibited by potassium metabisulphite) and Saccharomyces cerevisiae (MICs from 32 000- to 64 000-fold lower than potassium sorbate).
No in vitro synergistic interactions (calculated by FIC index -Σ FIC) are observed when killer protein is used in combination with the active compounds : potassium metabisulphite, potassium sorbate, or ethanol. The killer protein exhibited a dose–response effect against D.
bruxellensis and S. cerevisiae in a soft drink « Campari MIXX » (Milan, Italy) and pear juice « Santal » (Parma, Italy), respectively. The results of the present study suggest that the killer protein could be proposed as a novel food-grade compound useful for the control of food and beverage spoilage yeasts. Additionally, the purified killer protein maintains its killing action at
least for 3 days against S. cerevisiae DBVPG 6500 inoculated in pear juice and for 10 days against D. bruxellensis DBVPG 6706 in soft drink. The results of the present study suggest that the killer protein produced by the strain P. kluyveri (L5) could be proposed as a novel natural agent for the biocontrole of beverage spoilage yeasts.
Diplôme : Doctorat En ligne : ../theses/biologie/LAB6794.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10026 Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité LAB/6794 LAB/6794 Thèse Bibliothèque principale Thèses Disponible Isolement de microorganismes à partir du sol des régions arides et sélection d’isolats à effet antagoniste sur l’agent de l’Alternariose / Asma Milet
Titre : Isolement de microorganismes à partir du sol des régions arides et sélection d’isolats à effet antagoniste sur l’agent de l’Alternariose Type de document : texte imprimé Auteurs : Asma Milet, Auteur ; N Kacem Chaouche, Directeur de thèse Editeur : جامعة الإخوة منتوري قسنطينة Année de publication : 2017 Importance : 122 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles
Langues : Français (fre) Catégories : Français - Anglais
BiologieTags : Tomate Alternariose Alternaria alternata Bacillus Providencia vermicola lipopeptides Cymomètre à flux biocontrôle Tomato early blight Flow cytometer biocontrol ?????? ?????? ??????? ????? ???? ??????? ?????????
??????????Index. décimale : 570 Sciences de la vie. Biologie Résumé : Early blight is one of the most important diseases of tomato in eastern Algeria. Tomato
samples exploration (leaves, stems and fruits) with symptoms of early blight, grown under
glass in Hamma Bouziane locality (Constantine), allowed obtaining a filamentous fungal
isolate (Alt 1). The morphological and molecular identification (DNA-ITS analysis) of this
isolate revealed that it is Alternaria alternata (HQ846574.1). Pathogenicity testing of
seedlings by isolate resulted in the challenge of the typical early blight disease with a severity
of ≥ 76%. Samples exploration from various environments in the Algerian Sahara (Biskra and
Tougourt) resulted in the obtaining of 45 microbial isolates capable of developing an effect on
early blight agent. The selection test showed that; E1B3, S5 (isolated from Biskra) and E2X1,
S1.1 (isolated from Tougourt) possess a considerable antifungal effect against A. alternata
(inhibition rates vary between 60% and 75%), however, the E1B3 isolate developed the best
effect. The morphological and molecular identification of the selected isolates by analysis of
the 16S DNA and the "gyrase-A" gene showed that the bacterial isolates; E1B3, S5, and S1.1,
are identified as Bacillus mojavensis (KC977492), Bacillus amyloliquefaciens (KC977493),
and Bacillus Subtilis (KP699114.1) respectively, whereas the bacterial isolate E2X1 is
identified as Providencia vermicola (KP059130.1). To the best of our knowledge, the
isolation of P. vermicola from the palmerais rhizospheric soil and the demonstration of its
antifungal potential are established for the first time in this work.
The in vivo tests that carried out in pots and field conditions on tomato showed different
effects according to the bacterial species, and B. mojavensis developed the best effect
considering the most studied parameters (disease severity, Seedling size, leaves number and
flowers number per seedling). The P. vermicola strain showed the greatest result on the
severity reduction of early blight disease, indicating that the present work is the first one
which revealed this effect. In contrast, B. mojavensis developed the best protective effect,
considering the majority of the parameters studied in vitro and in vivo. This impact is due to
the ability of this strain to produce antifungal substances in this case; the enzymes (lipase and
protease) and the three families of lipopeptides (iturin, surfactins, and fengycins). The
evaluation of the antagonistic effect developed by B. mojavenssvis versus A. alternata through
flow cytometer (FCM) showed a considerable decrease in the rate of A. Alternata living cells,
confirming the inhibitory effect of B. mojavensis against the pathogenic agent of early blight.Diplôme : Doctorat En ligne : ../theses/biologie/MIL7125.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10477 Isolement de microorganismes à partir du sol des régions arides et sélection d’isolats à effet antagoniste sur l’agent de l’Alternariose [texte imprimé] / Asma Milet, Auteur ; N Kacem Chaouche, Directeur de thèse . - [S.l.] : جامعة الإخوة منتوري قسنطينة, 2017 . - 122 f. ; 30 cm.
2 copies imprimées disponibles
Langues : Français (fre)
Catégories : Français - Anglais
BiologieTags : Tomate Alternariose Alternaria alternata Bacillus Providencia vermicola lipopeptides Cymomètre à flux biocontrôle Tomato early blight Flow cytometer biocontrol ?????? ?????? ??????? ????? ???? ??????? ?????????
??????????Index. décimale : 570 Sciences de la vie. Biologie Résumé : Early blight is one of the most important diseases of tomato in eastern Algeria. Tomato
samples exploration (leaves, stems and fruits) with symptoms of early blight, grown under
glass in Hamma Bouziane locality (Constantine), allowed obtaining a filamentous fungal
isolate (Alt 1). The morphological and molecular identification (DNA-ITS analysis) of this
isolate revealed that it is Alternaria alternata (HQ846574.1). Pathogenicity testing of
seedlings by isolate resulted in the challenge of the typical early blight disease with a severity
of ≥ 76%. Samples exploration from various environments in the Algerian Sahara (Biskra and
Tougourt) resulted in the obtaining of 45 microbial isolates capable of developing an effect on
early blight agent. The selection test showed that; E1B3, S5 (isolated from Biskra) and E2X1,
S1.1 (isolated from Tougourt) possess a considerable antifungal effect against A. alternata
(inhibition rates vary between 60% and 75%), however, the E1B3 isolate developed the best
effect. The morphological and molecular identification of the selected isolates by analysis of
the 16S DNA and the "gyrase-A" gene showed that the bacterial isolates; E1B3, S5, and S1.1,
are identified as Bacillus mojavensis (KC977492), Bacillus amyloliquefaciens (KC977493),
and Bacillus Subtilis (KP699114.1) respectively, whereas the bacterial isolate E2X1 is
identified as Providencia vermicola (KP059130.1). To the best of our knowledge, the
isolation of P. vermicola from the palmerais rhizospheric soil and the demonstration of its
antifungal potential are established for the first time in this work.
The in vivo tests that carried out in pots and field conditions on tomato showed different
effects according to the bacterial species, and B. mojavensis developed the best effect
considering the most studied parameters (disease severity, Seedling size, leaves number and
flowers number per seedling). The P. vermicola strain showed the greatest result on the
severity reduction of early blight disease, indicating that the present work is the first one
which revealed this effect. In contrast, B. mojavensis developed the best protective effect,
considering the majority of the parameters studied in vitro and in vivo. This impact is due to
the ability of this strain to produce antifungal substances in this case; the enzymes (lipase and
protease) and the three families of lipopeptides (iturin, surfactins, and fengycins). The
evaluation of the antagonistic effect developed by B. mojavenssvis versus A. alternata through
flow cytometer (FCM) showed a considerable decrease in the rate of A. Alternata living cells,
confirming the inhibitory effect of B. mojavensis against the pathogenic agent of early blight.Diplôme : Doctorat En ligne : ../theses/biologie/MIL7125.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10477 Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité MIL/7125 MIL/7125 Thèse Bibliothèque principale Thèses Disponible
