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Involvement of Lignocellulolytic Enzymes in the Decomposition of Leaf Litter in a Subtropical Forest

Authors


Corresponding Author: Xing-Jun Tian, School of Life Science, Nanjing University, Nanjing, 210093, China—Telephone number: +86-25-8368-6787; FAX number: +86-25-8359-2705; e-mail: tianxj@nju.edu.cn

Abstract

ABSTRACT. The involvement of ligninolytic and cellulolytic enzymes, such as laccase, lignin peroxidase, manganese peroxidase, carboxymethylcellulase (CMCase), and filter paper activity (FPA), in the decomposition process of leaf litter driven by 6 soil-inhabiting fungi imperfecti was studied under solid-state fermentations. All the tested fungi exhibited varied production profiles of lignocellulolytic enzymes and each caused different losses in total organic matter (TOM) during decomposition. Based on the results, the 6 fungi could be divided into 2 functional groups: Group 1 includes Alternaria sp., Penicillium sp., Acremonium sp., and Trichoderma sp., and Group 2 includes Pestalotiopsis sp. and Aspergillus fumigatus. Group 1, with higher CMCase and FPA activities, showed a higher decomposition rate than the fungi of Group 2 over the first 16 d, and thereafter the cellulolytic activities and decomposition rate slowed down. Group 2 showed the maximum and significantly higher CMCase and FPA activities than those of the Group 1 fungi during the later days. This, combined with the much higher laccase activity, produced a synergistic reaction that led to a much faster average mass loss rate. These results suggest that the fungi of Group 1 are efficient decomposers of cellulose and that the fungi of Group 2 are efficient decomposers of lignocellulose. During cultivation, Pestalotiopsis sp. produced an appreciable amount of laccase activity (0.56±0.09 U/ml) without the addition of inducers and caused a loss in TOM of 38.2%±3.0%, suggesting that it has high potential to be a new efficient laccase-producing fungus.

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