Widespread Occurrence of Expressed Fungal Secretory Peroxidases in Forest Soils

Abstract

Fungal secretory peroxidases mediate fundamental ecological functions in the conversion and degradation of plant biomass. Many of these enzymes have strong oxidizing activities towards aromatic compounds and are involved in the degradation of plant cell wall (lignin) and humus. They comprise three major groups: class II peroxidases (including lignin peroxidase, manganese peroxidase, versatile peroxidase and generic peroxidase), dye-decolorizing peroxidases, and heme-thiolate peroxidases (e.g. unspecific/aromatic peroxygenase, chloroperoxidase). Here, we have repeatedly observed a widespread expression of all major peroxidase groups in leaf and needle litter across a range of forest ecosystems (e.g. Fagus, Picea, Acer, Quercus, and Populus spp.), which are widespread in Europe and North America. Manganese peroxidases and unspecific peroxygenases were found expressed in all nine investigated forest sites, and dye-decolorizing peroxidases were observed in five of the nine sites, thereby indicating biological significance of these enzymes for fungal physiology and ecosystem processes. Transcripts of selected secretory peroxidase genes were also analyzed in pure cultures of several litter-decomposing species and other fungi. Using this information, we were able to match, in environmental litter samples, two manganese peroxidase sequences to Mycena galopus and Mycena epipterygia and one unspecific peroxygenase transcript to Mycena galopus, suggesting an important role of this litter- and coarse woody debris-dwelling genus in the disintegration and transformation of litter aromatics and organic matter formation.

Cloning and expression of a new manganese peroxidase from Irpex lacteus F17 and its application in decolorization of reactive black 5

“…In terms of the sources of enzymes, LiPs occur in members of the Polyporales and Corticiales and VPs stem from the Agaricales and Polyporales, whereas MnPs occur in at least four orders, the Polyporales, Corticiales, Agaricales, and Corticiales [53,54], which explains why MnPs are prevalent in nature and also indicates that MnPs may have originated relatively early in the evolutionary history of class II fungal heme peroxidases. Moreover, this result supports the findings of Kellner et al [3], which showed that the widespread occurrence of this peroxidase type is of a strong biological significance for the conversion and degradation of plant biomass.…”

Patterns of laccase and peroxidases in coarse woody debris of Fagus sylvatica, Picea abies and Pinus sylvestris and their relation to different wood parameters

“…It must be considered that the GenP activities measured here represent sum activities that rely on several fungal peroxidases (Kellner et al 2014), among which only LiP and VP are truly ligninolytic (Hofrichter et al 2010;Ruiz-Dueñas and Martínez 2009). Consequently, the relation of LiP and VP to water-soluble lignin fragments could be masked/corrupted by activities of GP, UPO and DyP (Hofrichter et al 2010;Liers et al 2011).…”

“…The GenP activity stands for the sum activity of a genetically diverse set of fungal peroxidases that can include LiP, VP, GP, UPO and DyP in the absence of Mn 2? , which is why the GenP activity has also been described as activity of manganese-independent peroxidases (MiP; Kellner et al 2014). All measurements were taken in duplicate and were repeated when the absorbance increase in the two measurements was strongly deviating.…”

“…This complex interplay of fungal species may be the reason for the observed extreme variability (Table 3) and cannot be explained by solely analyzing the fungal community. For a better understanding of the secretion of fungal laccase and peroxidases, the analysis of the functional fungal community by expression studies for each enzyme based on transcriptomics will be useful (Kellner et al 2014). …”

Fire effects in the molecular structure of soil organic matter fractions under Quercus suber cover

“…This activity is prone to produce humic-type SOM and lignin degradation. In fact, the abundance of unspecific aromatic compounds could also have an origin in the fungal alteration of plant lignins (Kellner et al, 2014).…”