Bacterial succession on decomposing leaf litter exhibits a specific occurrence pattern of cellulolytic taxa and potential decomposers of fungal mycelia

Abstract

The decomposition of dead plant biomass contributes to the carbon cycle and is one of the key processes in temperate forests. While fungi in litter decomposition drive the chemical changes occurring in litter, the bacterial community appears to be important as well, especially later in the decomposition process when its abundance increases. In this paper, we describe the bacterial community composition in live Quercus petraea leaves and during the subsequent two years of litter decomposition. Members of the classes Alpha-, Beta- and Gammaproteobacteria and the phyla Actinobacteria, Bacteroidetes and Acidobacteria were dominant throughout the experiment. Bacteria present in the oak phyllosphere were rapidly replaced by other taxa after leaf senescence. There were dynamic successive changes in community composition, in which the early-stage (months 2-4), mid-stage (months 6-8) and late-stage (months 10-24) decomposer communities could be distinguished, and the diversity increased with time. Bacteria associated with dead fungal mycelium were important during initial decomposition, with sequence relative abundances of up to 40% of the total bacterial community in months 2 and 4 when the highest fungal biomass was observed. Cellulose-decomposing bacteria were less frequent, with abundance ranging from 4% to 15%. The bacterial community dynamics reflects changes in the availability of possible resources either of the plant or microbial origin.

Litter chemistry influences decomposition through activity of specific microbial functional guilds

“…These data support the view that bacteria can play a role in decomposition (Tláskal et al. , Pathan et al. ) and suggest phylogenetic overdispersion of decomposition traits within microbial kingdoms.…”

“…High percentage cellulose loss from litters in our study may be due to the activity of these cellulose‐degrading bacterial that mine the litter for cellulose, as others have recently observed cellulose‐degrading bacteria increasing in relative abundance during the course of litter decay (Tláskal et al. ).…”

“…However, others have noticed that some bacteria increase in abundance during the later stages of litter decomposition, when lignin concentration is high (Tláskal et al. ). The cellulose guilds, for both fungi and bacteria, increased significantly on low lignin plants, supporting the hypothesis that lignin protects cellulose from attack by decomposers (Talbot et al.…”

“…) and that bacteria can be important to cellulose decay later in the litter decomposition process (Tláskal et al. ).…”

Bacterial communities of decaying Norway spruce follow distinct slope exposure and time‐dependent trajectories

“…The majority of sequences were annotated as Proteobacteria (Supporting Information Fig. S5), which is in line with previous studies on P. abies, Fagus sylvatica and Pinus sylvestris wood decay (Valášková et al ., ; Sun et al ., ; Hoppe et al ., ; Hervé et al ., ; Kielak et al ., ; Rinta‐Kanto et al ., ) and with other wood decay associated environments such as leaf litter (Tláskal et al ., ). Furthermore, Acido‐ and Actinobacteria were also found in high richness and abundance (Supporting Information Fig.…”