16 research outputs found

    Evaluation de l'activité antagoniste entre microorganismes lignicoles : recherche des possibilités d'utilisation en préservation des poteaux électriques d'HydroQuébec

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    Cette étude menée au CIRAD concerne l'activité antagoniste de trois ascomycètes du genre Trichoderma : Trichoderma konigii, Trichoderma harzianum et Trichoderma viride, par confrontations directes en boîtes de Pétri et dans le bois des poteaux électriques d'HydroQuébec vis-à-vis de deux basidiomycètes de pourriture fibreuse Pycnoporus sanguineus et Coriolus versicolor et vis-à-vis de deux basidiomycètes de pourriture cubique, Antrodia sp. et Coniophora puteana. Les résultats obtenus semblent se compléter généralement de façon cohérente. Ils montrent la non-agressivité du groupe des champignons des Trichoderma vis-à-vis du bois et les résultats obtenus après les confrontations directes en boîtes de Pétri se confirment dans le bois. Les confrontations directes, en boîtes de Pétri, des différents basidiomycètes et antagonistes pris deux par deux, nous permettent effectivement de mettre en évidence un effet d'antagonisme pour une grande majorité des couples. Toutefois, il existe une grande variabilité dans les réactions d'un couple à l'autre. Ainsi, le mode d'antagonisme d'un même Trichoderma peut varier d'un basidiomycète à l'autre, et inversement un même basidiomycète pourra répondre différemment à chaque antagoniste qui lui est opposé.(Résumé d'auteur

    Molecular characterization and biodiversity of wood-decaying fungi in French Guiana

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    Fungi from tropical regions are currently under-represented in the classification system. Indeed, difficult access to tropical forests and irregular occurrence carpophores make it complicated to study fungus species in such environments, unlike in European zones where fungal diversity and taxonomy are better known. The purpose of this work was to enhance classification by integrating new data that would bring out the importance of certain traits of these fungi, and provide a clearer understanding of how the biodiversity of fungi from the forest ecosystems of French Guiana is organized, particularly those causing wood decay through white rot, brown rot or soft rot. In our study, we chose to work in the zone comprising the internal transcribed spacers ITS1 and ITS2, which are relatively variable, and the 5.8 S small ribosomal subunit, which is not highly variable. The primers ITS 1(5'-TCCGTAGGTGAACCTGCGC-3') and ITS 4 (5'-TCCTCCGCTTATTGATATGC-3'), specific to fungi, were chosen for this taxonomic analysis of the studied species. This study was carried out on 101 fungus fruiting bodies at the Paracou forest site in French Guiana. Of those 101 fungi, 72 were identified by BLASTn. Four species were Ascomycetes of the genus Muscodor and Xylaria. The other 68 species, all in the class of the Basidiomycetes, were divided into the following orders: 31 Agaricales, 1 Atheliales, 2 Boletales, 1 Gomphales, 12 Polyporales, 1 Trechisporales and 1 Tremellales. There was also an indeterminate taxon very similar to the lichens. Within the order Polyporales, the main genera were found, such as Antrodiella, Coriolopsis, Fomitopsis, Ganoderma, Lentinus, Pycnoporus, Steccherinum, Trametes, Fomitoporia. All these fungi have the particularity of causing wood decay. (Résumé d'auteur

    Molecular diagnosis by PCR- technique of wood-decay fungi in historical buildings in Italy

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    Wood inhabiting fungi cause real problems in the preservation of wooden surfaces and are responsible for the deterioration of cultural heritage. The identification of fungi based on morphological characteristics are still a topical issue. Nevertheless, they are limited for characterization and identification on an intraspecific level and even sometimes on an interspecific level. It is not always evident and thus many fungi remain unnamed or confused. The objective of this study was to circumvent these limitations by using a new molecular approach allowing fungal detection and identification in historic buildings in Italy. Fungal colonization was assessed by using PCR amplification and amplicons separation by Denaturing High Performance Liquid Chromatography. Due to its high sensitivity, the PCR-DHPLC technique was optimised to profile fungal communities in wood decay as well as ubiquitous contaminants. (Abstract

    Natural protection of wood with antagonism fungi

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    Biological environments contain a certain number of microbial populations which, within a given ecological niche, display various relations ranging from symbiosis to parasitism. Researchers have been interested in these types of relations for around fifty years, especially in one very particular type of relationship: the antagonism exerted between individuals of the same microbial population. Today, the role played by biological agents, bringing into play inhibitive or destructive antibiotic substances, reveals a certain potential for their use in controlling microorganisms associated with such degradation processes. The work undertaken by HydroQuébec and CIRAD involved two types of experiment: 1) in Petri dishes to assess and characterize the antagonistic capacity of Trichoderma against white rot and brown rot fungi; 2) on pieces taken from untreated poles in order to study confrontation between the basidiomycete and the antagonistic strain in wood. This study investigated the antagonism of three ascomycetes of the genus Trichoderma against two white rot basidiomycetes, Pycnoporus sanguineus and Coriolus versicolor, and two brown rot basidiomycetes, Antrodia sp. and Coniophora puteana, through direct confrontation in Petri dishes and in the wood of HydroQuébec poles. The results obtained seemed to complete each other coherently. They revealed that the Trichoderma group of fungi was not aggressive to wood and the results obtained after direct confrontation in Petri dishes were confirmed in wood. By directly exposing the different basidiomycetes and antagonists to each other in Petri dishes, two by two, we effectively revealed an antagonism effect for a large majority of the pairs. However, there was substantial variability in reactions from one pair to the next. (Résumé d'auteur

    Molecular diagnosis by PCR-DHPLC technique of wood-decay fungi in historical buildings in Italy

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    Wood inhabiting fungi cause real problems in the preservation of wooden surfaces and are responsible for the deterioration of cultural heritage. The identification of fungi based on morphological characteristics are still a topical issue. Nevertheless, they are limited for characterization and identification on an intraspecific level and even sometimes on an interspecific level. It is not always evident and thus many fungi remain unnamed or confused. The objective of this study was to circumvent these limitations by using a new molecular approach allowing fungal detection and identification in historic buildings in Italy. Fungal colonization was assessed by using PCR amplification and amplicons separation by Denaturing High Performance Liquid Chromatography. Due to its high sensitivity, the PCR-DHPLC technique was optimised to profile fungal communities in wood decay as well as ubiquitous contaminants. (Résumé d'auteur

    Monitoring fungal diversity to determine the geographical origin of exotic timbers

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    Wood is an important economical resource for many tropical countries. Among the benefits of most of the tropical woody species, we can mention their natural durability and their capacity of withstanding outside environment without the use of chemical preservatives. Also, many of these tropical species show undeniable properties that people looked for such as aesthetic appearance and good mechanical property. Different marking systems are available in order to facilitate the traceability of wood but they present some limitations in their use at a larger scale. This study aims at developing a reliable technique to asses the geographical origin of different wood species. Wood can be colonized by destroying fungal microorganisms known as endophyte. The main objective of this work is to use these microorganisms as a molecular marker. An amplification of the ITS region has been done and used with CE-SSCP on tree different tropical species from 6 countries: Limba (Terminalia superba), Limbali (Gilbertiodendron dewerei-preussii) and Teak (Tectona grandis). Results show a grouping among different microbial profiles related to the wood species and discernment between Limba and Limbali. We show that microbial profiles could be used as a marker to ensure the proper origin of wood as part of an ecocertification for sustainable management of the forest. Also, they will help in controlling the itinerary of a wood product from forest to consumer. (Résumé d'auteur

    Molecular diagnosis by PCR-DHPLC technique of wood-decay fungi in historical buildings in Italy

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    Wood inhabiting fungi cause real problems in the preservation of wooden surfaces and are responsible for the deterioration of cultural heritage. The identification of fungi based on morphological characteristics is still a topical issue. Nevertheless, they are limited for characterization and identification on an intraspecific level and even sometimes on an interspecific level. It is not always evident and thus many fungi remain unnamed or confused. The objective of this study was to circumvent these limitations by using a new molecular approach allowing fungal detection and identification in historic buildings in Italy. Fungal colonization was assessed by using PCR amplification and amplicons separation by Denaturing High Performance Liquid Chromatography. Due to its high sensitivity, the PCR-DHPLC technique was optimised to profile fungal communities in wood decay as well as ubiquitous contaminants. (Résumé d'auteur

    Ability of tropical forest soils of French Guiana and Reunion to depollute woods impregnated with biocides

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    Our study sought to fine-tune knowledge about those microorganisms, particularly wood-decaying fungi degrading pollutants in situ. With a view to the depollution or bioremediation of treated woods, wood-decaying microorganisms from tropical forest soils in French Guiana and the island of Reunion were assessed for their ability to degrade toxic biocides such as pentachlorophenol (PCP) or copper chromium arsenic compounds (CCA). The degradation of red pine (Pinus resinosa) test pieces was monitored and it was found that the soil from French Guiana was more efficient than the soil from Reunion in terms of microbial activity in relation to these two biocides. A significant difference in weight loss was found for the red pinetest pieces treated with CCA and PCP, varying in a ratio of one to two (18% and 30%, respectively). In addition, a study of wood and soil fungus communities using D-HPLC and CE-SSCP, then analysed by a PCA, showed that biocide products leached into the soil had an impact on the fungus communities, which differed depending on the sampling time and on the wood treatment. Lastly, these results confirmed that CCA was less leachable and less degradable by microorganisms in these soils than PCP. (Résumé d'auteur

    Capacité des sols forestiers tropicaux de Guyane et de la Réunion à dépolluer les bois imprégnés de biocides

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    Le matériau bois a depuis longtemps fait l'objet de traitements fongicides ou insecticides dont l'impact sur les sols après lessivage constitue un réel problème écologique. À ce jour, l'essentiel des études sur la dégradation de ces produits toxiques a été mené à partir des micro-organismes isolés en laboratoire. La présente étude a cherché à affiner les connaissances concernant ces microorganismes, en particulier les champignons lignivores dégradant les polluants in situ, pour lesquels peu de données sont en fait disponibles. En vue de dépolluer des bois traités, la capacité des micro-organismes lignivores issus de sols forestiers tropicaux de la Guyane et de la Réunion pour dégrader des biocides toxiques a été évaluée. Il s'agit du pentachlorophénol (PCP) et des composés à base de cuivre chrome arsenic (CCA). Le suivi de la dégradation d'éprouvettes de pin rouge, Pinus resinosa, montre que le sol de Guyane est plus performant que celui de la Réunion en termes d'activité microbienne vis-à-vis de ces deux biocides. Une différence significative de la perte de masse des éprouvettes de pin rouge traitées au CCA et au PCP peut aller du simple au double (respectivement 18 % et 30 %). Ces résultats confirment que le CCA est moins lessivable et moins dégradable par les microorganismes de ces sols que le PCP. D'après le barème des pertes de masse en essais de laboratoire, ces bois ainsi traités seraient classés peu durables après trois ans de mise en contact avec le sol, alors que le traitement est prévu comme très durable. (Résumé d'auteur
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