Changes of the phenol-degrading bacterial community during the decomposition of submersed Platanus acerifolia leaves

Authors


Correspondence: Lluís Bañeras, Ma Aurèlia Capmany, 69, E-17071 Girona, Spain. Tel.: +34 972418177; fax: +34 972418150; e-mail: lluis.banyeras@udg.edu

Abstract

Microorganisms are responsible for the decomposition of plant litter due to their enhanced enzyme capabilities. Among extracellular enzymes, those involved in lignin decomposition are especially relevant in leaf degradation. However, the knowledge of the bacterial contribution to the decomposition of phenol-derived compounds in submerged leaf litter is limited. We have used the large unit of the multicomponent bacterial phenol hydroxylase (LmpH) as a genetic proxy to describe changes in the phenol-degrading bacterial community during the decomposition of Platanus acerifolia leaves in a forested stream. Significant differences were found in the phenol-degrading community when three decomposition stages, initial (day 7), midterm (day 58), and late (day 112), were compared. Estimated Shannon's diversity values decreased significantly from 1.93 (initial) to 0.98 (late). According to the deduced amino acid sequences and the corresponding theoretical kinetic parameters of phenol hydroxylases, the initial community showed a low degree of specialization, presumably resulting from random colonization of leaves. At the late decomposition stage, the bacterial community became more specialized, and LmpH genes similar to high-affinity phenol hydroxylases of Comamonas sp. and Burkholderia cepacia increased. The observed changes in the bacterial community suggested an active role of bacteria during litter decomposition in aquatic environments.

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