UniFrac distances ranged from 0.298 to 0.607 and were higher between the initial and late stage samples. UniFrac tests have been previously used as a semi-quantitative determination of the similarities between the bacterial communities on the phyllosphere of Populus deltoides sampled at different times (Redford et al., 2010). According to our estimations, major changes

in the phenol-degrading bacterial community may occur between the initial and midterm stages of leaf decomposition. At the midterm, the greatest community richness and diversity was found and coincided with increasing phenol RG7204 oxidase activity and maximum fungal biomass (Artigas et al., 2011). The LmPH sequences from this stage were scattered throughout the phylogenetic tree (in clusters A, B, C, and E), and their corresponding enzymes exhibit different kinetic properties. find more It is known that bacteria and fungi have complementary roles in leaf litter degradation. Bacteria are thought to increase their contribution only after leaf material has been partially broken down (Baldy et al., 1995), whereas fungi, especially

aquatic hyphomycetes, have been recognized as dominant, in terms of both activity and biomass, during early decomposition (Gulis & Suberkropp, 2003; Romaní et al., 2006). However, bacteria may make a greater contribution to leaf litter decomposition particularly when fungal activity is compromised by unfavorable conditions (Pascoal & Cassio, 2004; Kubartova et al., 2009). In conclusion, by analyzing the LmPH gene from different leaf decomposition stages, we have shown that the bacterial community changes significantly over the course of leaf litter degradation in streams. During Orotidine 5′-phosphate decarboxylase early decomposition, the bacterial community is rather complex and potentially exhibits a low degree of metabolic

specialization in view of the deduced enzyme kinetics. As decomposition progresses, the phenol-degrading bacterial community is dominated by suspected low-Ks type bacteria, with a high similarity to Alcaligenes spp., Comamonas sp., and Ralstonia sp, suggesting a gradual selection of specialized phenol degraders as decomposition progressed. To the best of our knowledge, this work represents the first specific analysis of any functional gene marker and of bacterial and fungal origin, used for investigating microbial communities during the leaf litter decomposition process in streams. Time series analyses of bacterial and fungal communities in leaf litter decomposition have previously been performed using either DGGE or terminal-restriction fragment length polymorphism (T-RFLP) of amplified SSU rRNA fragments (Das et al., 2007; Marks et al., 2009; Kelly et al., 2010), although no general conclusions can be derived from these studies. The relative presence of general and specialized microorganisms on leaf surfaces during litter decomposition has been proposed as a major determinant of diversity (Das et al., 2007).