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Abstract Detail

Mycological Section

Kellner, Harald [1], Arnstadt, Tobias [1], Leonhardt, Sabrina [1], Hoppe, Björn [2], Hofrichter, Martin [1].

Fungal enzyme activities during dead wood decomposition in temperate forests.

A substantial part of terrestrial carbon is bound in wood. After die-back, this source is continuously degraded by microorganisms, hereby structuring forest ecosystems and influencing multiple ecosystem functions, like carbon sequestration, nutrient cycling, and habitation of wood-dwelling organisms. However, detailed analyses of extracellular fungal enzymes during the course of wood decay in situ are still largely lacking.
In the German Biodiversity Exploratories (DFG Priority Programme 1374), we have followed the decomposition of natural occurring dead wood (Fagus sylvatica, Pinus sylvestris, Picea abies; total: 735 analyzed logs), which is representative for temperate forests in Central Europe. Moreover, an artificial long-term dead wood experiment (BELongDead) was designed and has started in the Exploratories in 2008. It includes logs of seven deciduous and four coniferous tree species replicated across 30 plots, to follow the decomposition processes during the coming decade.
A diverse set of lignocellulolytic hydrolases (e.g. β-glucanase, cellobiohydrolase, endocellulase, xylanase, β-xylosidase) and oxidoreductases (e.g. laccase, Mn-dependent and Mn-independent peroxidases), were measured using a set of photometric and HPLC assays. In parallel, several physicochemical wood parameters (e.g. lignin content, extractives, element content, pH, etc.) were analyzed. Correlations and regressions between enzymes and wood parameters in natural occurring dead wood revealed so far two main findings: i) the water content and the amount of soluble lignin fragments are important determinants, and ii) a moderate acidic pH (4.5-5.5) promotes the secretion and activity of laccase and manganese peroxidase, which is in agreement with numerous laboratory studies. Hydrolase activities are also frequently present in the analyzed tree species, and are currently being correlated to wood parameter and molecular fungal species richness.
To understand the underlying molecular mechanisms, we aim at analyzing the expressed fungal enzyme-encoding genes as well. For the time being, we have detected partially expressed class II peroxidases in beech logs, which include the key enzyme of lignin decay – manganese peroxidase (MnP, EC
Altogether, using the above approaches, we expect to come to a more detailed understanding of wood decay in temperate forest ecosystems.

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1 - International Institute Zittau, Technische Universität Dresden, Department of Bio- and Environmental Sciences, Markt 23, Zittau, 02673, Germany
2 - UFZ - Helmholtz Center for Environmental Research, Department of Soil Ecology, Theodor-Lieser Str. 4, Halle/Saale, 06120, Germany

lignocellulose decomposition
wood decay fungi
wood chemistry.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Hall D/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 5:30 PM
Number: PMY043
Abstract ID:344
Candidate for Awards:None

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