UNIVERSITÉ PAUL CÉZANNE, AIX MARSEILLE III - IMEP

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Résultats et discussion. Chapitre 1 : Criblage des souches de L. edodes 3.7. Phenolic monomer compound Ethyl acetate OMW extracts were analyzed with reversed-phase HPLC in order to assess degradation of individual monomeric aromatic components (Table 3). Chromatographic analyses showed that the strain Le119 was capable of completely removing hydroxytyrol, caffeic acid, and para-coumaric acid. The removal of other phenolic compounds was of 67.12% and 89.81% for vannilic acid and tyrosol, respectively. The other three strains (Le118, Le121, Le122) completely removed at least one compound, and partially removed 22% of oleuropein (strain Le122) and 93.25% of para-coumaric acid (Le118). Non- phenolic compound, such as trans-cinnamic acid, was not degraded. Table 3: Monomeric aromatic compound removal (%) with four L. edodes strains (Le118, Le119, Le121 and Le122), in liquid culture of OMW at 25°C after 30 days of incubation. OMW component Le118 Le119 Le121 Le122 3,4-Dihydroxyphenylethanol (hydroxytyrosol) 67 100 57 73.51 4-Hydroxyphenylethanol (tyrosol) 88.83 89.81 79.04 77 (+)-Catechin 73.35 68.98 100 65 Vannilic acid 0 67.12 20.29 11.97 Caffeic acid 100 100 100 100 Para-Coumaric acid 93.25 100 53.07 100 Trans-Cinnamic acid 0 0 0 0 Oleuropein 74.07 77.85 84.14 22 4. Discussion The use of cellophane membrane allowed the growth of all strains studied of L. edodes, as well as the color change of OMW agar medium after incubation (PDA containing 10% and 20% OMW). The initial color was black turning to clear brown after incubation, excepting the strain Le118 which exhibited dark color at the end of colonization. This change of color is an indicator of the action of fungal enzymes on the hydrolysis of phenols during mycelial growth (Sobal et al., 2003). The presence of OMW in the culture medium affected mycelial growth of all strains. Three selected strains (Le119, Le121, Le122) showed mycelial colonies of high density, while the strain Le118 had low density. The use of PDA allowed better assessment of decolorization efficiency in all strains. In fact, it has been 67
Résultats et discussion. Chapitre 1 : Criblage des souches de L. edodes shown that the metabolism for decolorization requires the presence of readily available carbon source, such as glucose (D’Annibale et al., 1998). Enzymatic determination using ABTS (2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) test (Collins et al., 1998), showed that most selected strains, except Le118, were capable of producing laccase on PDA without OMW (data not shown). Comparative assessment, based on apical growth rate and biomass yield on OMW agar medium, showed that the strains Le118, Le119, Le121 and Le122 were the most efficient, and accordingly selected for further evaluation of decolorization and the removal of total phenol from OMW. The inhibitory effects of OMW on fungi have already been reported (Fountoulakis et al., 2002; Alaoui et al., 2008). Considering this fact, dilutions of OMW were prepared to allow mycelial growth of L. edodes. In this study, the use of mycelium previously grown on PDA containing 2% of OMW resulted in enhanced tolerance of strains to inhibitory compounds from liquid OMW. This positive effect of pre-adaptation to OMW, previously reported for several white-rot fungi (Leontievsky et al., 2002; D’Annibale et al., 2004), has been attributed to the triggering effect of phenolic compounds for inducing the production of ligninolytic enzymes (Fenice et al., 2003 ; Farnet et al., 2004). Laccase was detected as the main lignin-degrading enzyme in strains studied, which was similar to previous reports (D’Annibale et al., 2004; Olivieri et al., 2006). It has also been reported that LiP and MnP are capable of decolorizing and removing phenolics from OMW (Sayadi and Ellouz 1993, 1995). The molecular weight of phenolic compound from OMW was modified by all strains at different levels. The strains Le119 and Le121 were able to reduce all fractions obtained from OMW extract. This was in agreement with previous results from Jouani et al. (2003) and D’Annibale et al. (2004). However, Casa et al. (2003) reported the appearance of a novel phenolic fraction in OMW after treatment with laccase. The difference of distribution patterns from aromatic compounds was also observed in OMW incubated with the fungus P. chrysosporium in liquid culture, which was associated to the production of LiP, and with purified LiP (Sayadi and Ellouz, 1993, 1995). This interpretation is based on the assumption that other auxiliary degradative mechanisms involving enzymes and small molecular weight agents, such as hydrogen peroxide and oxalic acid (D’Annibale et al., 1998), are implicated in the breakdown of aromatic substances, which could serve as substrates brought about by white-rot fungi (Durán and Esposito, 2000). The 68
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UNIVERSITÉ PAUL CÉZANNE, AIX MARS
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Je remercie le Dr. Antonis PHILIPPO
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Résumé L’objectif du travail a
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2.2.4.2. Culture de champignons sup
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3.7.1. La mesure de l’humidité .
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Liste des Tables Tableau 1. Bilan m
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1. INTRODUCTION Introduction Au Mar
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Introduction L'utilisation de la fe
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Matériel et Méthodes Figure 2. Ev
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Matériel et Méthodes et de l’hu
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Matériel et Méthodes composition
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Matériel et Méthodes Il ressort d
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Matériel et Méthodes catéchol-m
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Résultats et discussion. Chapitre
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ABSTRACT Résultats et discussion.
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3. Results and discussion Résultat
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Synthèse générale 142
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Synthèse générale produits de l
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Synthèse générale Suite à l’o
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Synthèse générale molécules ren
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Conclusions et perspectives 150
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Conclusions et perspectives La mise
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Références bibliographiques Réf
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Références bibliographiques Bing
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Références bibliographiques D'Ann
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Références bibliographiques mill
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Références bibliographiques Jo J.
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Références bibliographiques Match
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Références bibliographiques Zerva
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UNIVERSITÉ PAUL CÉZANNE, AIX MARSEILLE III - IMEP

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