The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Thierry Lebeau - One of the best experts on this subject based on the ideXlab platform.
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Bacterial and fungal communities vary with the type of organic substrate: implications for biocontrol of soilless crops
Environmental Chemistry Letters, 2017Co-Authors: Virginie Montagne, C. Grosbellet, Hervé Capiaux, Matthieu Barret, Sylvain Charpentier, Patrice Cannavo, Thierry LebeauAbstract:Biocontrol strategies using organic substrates such as Wood Fibers and biocontrol agents such as Trichoderma are currently developed to control soil pathogens such as Fusarium oxysporum. Nonetheless, such biocontrol methods give discording results, notably because microbial communities of organic substrates actually are not taken into account. Therefore, there is a lack of information concerning the variability of microbial composition related to the organic substrate type. Here we studied peat, Wood and coir Fibers, that are substrates known for their different biocontrol efficiency against Fusarium wilt of cucumber. We analyzed in microcosms the microbial composition of Wood Fibers, coir Fibers and peat, incubated up to 60 days, by using an amplicon-sequencing approach based on 16S rRNA gene for bacteria and the internal transcribed spacer (ITS) for fungi. Diversity was assessed by sequencing the 16S rRNA for bacteria and ITS2 region for fungi. Results showed that bacterial richness was threefold higher for coir fiber and peat than for Wood fiber. Fungal richness was three times higher for Wood and coir Fibers compared to peat. Bacterial and fungal patterns showed a dominance of α- and γ- Proteobacteria and Sordariomycetes for coir fiber; β- and γ-Proteobacteria and Eurotiomycetes for Wood Fibers; Flavobacteria, Leotiomycetes and Sordariomycetes for peat. In conclusion, results show that substrates have different microbial composition. Finally, for a proper use of a biocontrol strategy is important to take into account the type of substrate.
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Structure and activity of spontaneous fungal communities in organic substrates used for soilless crops
Scientia Horticulturae, 2015Co-Authors: Virginie Montagne, C. Grosbellet, Hervé Capiaux, Sylvain Charpentier, Patrice Cannavo, Thierry LebeauAbstract:Microbiological activity in substrates is of considerable concern for stability of the material and control of plant pathogens in the root environment. This study analyzes the structure of spontaneous microbial communities in various organic substrates used for soilless crops. Different Wood Fibers, coir Fibers and peats were incubated in controlled conditions. The activity of indigenous microorganisms was monitored by assessing substrate mineralization (CO2 released by substrates, potential enzymatic activity and lignocellulosic composition). The genetic structure of the fungal communities was analyzed by PCR-TTGE. Behavior was repeatable across different batches. Potential enzymatic activity was poorly correlated to microbial respiration and lignocellulosic composition. Microbial structure was specific to each substrate. The highest microbial specificity was for Wood Fibers, then coir Fibers, and finally peats. Our data indicated that microbial activity strongly depends on substrate origin and manufacturing process. Our results suggest that spontaneous development of microorganisms within a substrate could have specific effects on organic matter evolution and disease control.
Virginie Montagne - One of the best experts on this subject based on the ideXlab platform.
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Bacterial and fungal communities vary with the type of organic substrate: implications for biocontrol of soilless crops
Environmental Chemistry Letters, 2017Co-Authors: Virginie Montagne, C. Grosbellet, Hervé Capiaux, Matthieu Barret, Sylvain Charpentier, Patrice Cannavo, Thierry LebeauAbstract:Biocontrol strategies using organic substrates such as Wood Fibers and biocontrol agents such as Trichoderma are currently developed to control soil pathogens such as Fusarium oxysporum. Nonetheless, such biocontrol methods give discording results, notably because microbial communities of organic substrates actually are not taken into account. Therefore, there is a lack of information concerning the variability of microbial composition related to the organic substrate type. Here we studied peat, Wood and coir Fibers, that are substrates known for their different biocontrol efficiency against Fusarium wilt of cucumber. We analyzed in microcosms the microbial composition of Wood Fibers, coir Fibers and peat, incubated up to 60 days, by using an amplicon-sequencing approach based on 16S rRNA gene for bacteria and the internal transcribed spacer (ITS) for fungi. Diversity was assessed by sequencing the 16S rRNA for bacteria and ITS2 region for fungi. Results showed that bacterial richness was threefold higher for coir fiber and peat than for Wood fiber. Fungal richness was three times higher for Wood and coir Fibers compared to peat. Bacterial and fungal patterns showed a dominance of α- and γ- Proteobacteria and Sordariomycetes for coir fiber; β- and γ-Proteobacteria and Eurotiomycetes for Wood Fibers; Flavobacteria, Leotiomycetes and Sordariomycetes for peat. In conclusion, results show that substrates have different microbial composition. Finally, for a proper use of a biocontrol strategy is important to take into account the type of substrate.
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Structure and activity of spontaneous fungal communities in organic substrates used for soilless crops
Scientia Horticulturae, 2015Co-Authors: Virginie Montagne, C. Grosbellet, Hervé Capiaux, Sylvain Charpentier, Patrice Cannavo, Thierry LebeauAbstract:Microbiological activity in substrates is of considerable concern for stability of the material and control of plant pathogens in the root environment. This study analyzes the structure of spontaneous microbial communities in various organic substrates used for soilless crops. Different Wood Fibers, coir Fibers and peats were incubated in controlled conditions. The activity of indigenous microorganisms was monitored by assessing substrate mineralization (CO2 released by substrates, potential enzymatic activity and lignocellulosic composition). The genetic structure of the fungal communities was analyzed by PCR-TTGE. Behavior was repeatable across different batches. Potential enzymatic activity was poorly correlated to microbial respiration and lignocellulosic composition. Microbial structure was specific to each substrate. The highest microbial specificity was for Wood Fibers, then coir Fibers, and finally peats. Our data indicated that microbial activity strongly depends on substrate origin and manufacturing process. Our results suggest that spontaneous development of microorganisms within a substrate could have specific effects on organic matter evolution and disease control.
Behbood Mohebby - One of the best experts on this subject based on the ideXlab platform.
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Hydrothermally treated Wood as reinforcing filler for natural rubber bio-composites
Journal of Polymer Research, 2017Co-Authors: Fatemeh Tavassoli, Mehdi Razzaghi-kashani, Behbood MohebbyAbstract:Hydrothermal treatment was considered as a method for modification of oriental beech Wood to be used as reinforcing filler for natural rubber. Surface energy of treated Wood Fibers and their interaction with natural rubber were studied by water contact angle of Wood and dynamic-mechanical-thermal analysis of formed bio-composites and compared with those for untreated and silane-treated Wood Fibers. Hydrothermal treatment of Wood was performed at two temperatures of 140 °C and 160 °C, and bio-composites were prepared by melt mixing method. Results showed that water contact angle of untreated Wood increases by hydrothermal treatment and silane modification of Wood Fibers, which the latter has the highest value. Dynamic-mechanical-thermal analysis of bio-composites showed that hydrothermal treatment reduced interactions between Wood Fibers and increased interaction between Fibers and rubber which resulted in better dispersion of Fibers, observed by scanning electron microscopy. In order to investigate reinforcing effect of hydrothermally treated Wood Fibers, mechanical properties of bio-composites in tension was studied, and improvement in tensile strength and elongation at break for bio-composites containing treated Fibers was observed, which was correlated to the stronger Wood fiber-rubber interface compared to untreated ones. Wood Fibers treated at 140 °C showed better mechanical properties, which was comparable with silane modified Fibers.
Leif H Skibsted - One of the best experts on this subject based on the ideXlab platform.
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identification and quantification of radical reaction intermediates by electron spin resonance spectrometry of laccase catalyzed oxidation of Wood Fibers from beech fagus sylvatica
Applied Microbiology and Biotechnology, 1997Co-Authors: Claus Felby, Bo R Nielsen, Per Ole Olesen, Leif H SkibstedAbstract:During laccase-catalyzed oxidation of beech Wood Fibers in an aqueous suspension, phenoxy radicals were detected in steady-state concentrations by electron-spin resonance (ESR) spectrometry of the suspension liquid, suggesting that colloidal lignin functions as a mediator between laccase and the fiber lignin matrix. Phenoxy radicals were observed directly, whereas ESR spin-trapping techniques gave no evidence for reduced oxygen species, such as the superoxide or hydroxyl radical. A reaction mechanism involving parallel direct oxidation of the lignin on fiber surfaces and a phenol/phenoxy cyclic mediator process in the suspension liquid could accordingly describe laccase-catalyzed oxidation of beech Wood Fibers. Cytochrome c assays for detection of superoxide in systems involving lignin oxidized by oxidoreductases should be used with caution, as cytochrome c may be reduced by species other than superoxide.
Yuanlin Cao - One of the best experts on this subject based on the ideXlab platform.
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determination of reactive oxygen species generated in laccase catalyzed oxidation of Wood Fibers from chinese fir cunninghamia lanceolata by electron spin resonance spectrometry
Bioresource Technology, 2009Co-Authors: Guanwu Zhou, Yongsheng Chen, Baolu Zhao, Yongjian Cao, Xinfang Duan, Yuanlin CaoAbstract:Abstract The aim of the present study was to determine whether the radical reaction intermediates – reactive oxygen species (ROS) were formed during the laccase-catalyzed oxidation of Wood Fibers from Chinese fir (Cunninghamia lanceolata) and to quantify tentatively its production with electron spin resonance (ESR) spectrometry. To investigate the activation pathways triggered by laccase, ESR spin-trapping techniques using N-tert-butyl-α-phenylnitrone (PBN) as spin trap followed by ethyl acetate extraction were employed to identify and quantify the free radical intermediates. ROS such as the superoxide and hydroxyl radical was detected and quantified in the laccase catalyzed oxidation of Wood Fibers, suggesting that ROS is the main free radical intermediates for laccase reaction. Based on the findings of the presence of ROS and previous literature on the free radical reaction of laccase oxidation of Wood Fibers, a possible reaction mechanism involving ROS-mediated attack on the domains of lignin which is not directly accessible for the enzyme and solubilized low-molecular mass lignins which function as reactive compounds like adhesives and may cling back to the fiber surface, could accordingly describe laccase-catalyzed oxidation of Chinese fir Wood Fibers.
