Molecular characterization of aromatic peroxygenase from Agrocybe aegerita

Recently, a novel group of fungal peroxidases, known as the aromatic peroxygenases (APO), has been discovered. Members of these extracellular biocatalysts produced by agaric basidiomycetes such as Agrocybe aegerita or Coprinellus radians catalyze reactions--for example, the peroxygenation of naphthalene, toluene, dibenzothiophene, or pyridine--which are actually attributed to cytochrome P450 monooxygenases. Here, for the first time, genetic information is presented on this new group of peroxide-consuming enzymes. The gene of A. aegerita peroxygenase (apo1) was identified on the level of messenger RNA and genomic DNA. The gene sequence was affirmed by peptide sequences obtained through an Edman degradation and de novo peptide sequencing of the purified enzyme. Quantitative real-time reverse transcriptase polymerase chain reaction demonstrated that the course of enzyme activity correlated well with that of mRNA signals for apo1 in A. aegerita. The full-length sequences of A. aegerita peroxygenase as well as a partial sequence of C. radians peroxygenase confirmed the enzymes' affiliation to the heme-thiolate proteins. The sequences revealed no homology to classic peroxidases, cytochrome P450 enzymes, and only little homology (<30%) to fungal chloroperoxidase produced by the ascomycete Caldariomyces fumago (and this only in the N-terminal part of the protein comprising the heme-binding region and part of the distal heme pocket). This fact reinforces the novelty of APO proteins. On the other hand, homology retrievals in genetic databases resulted in the identification of various APO homologous genes and transcripts, particularly among the agaric fungi, indicating APO's widespread occurrence in the fungal kingdom

Data from: Life in leaf litter: novel insights into community dynamics of bacteria and fungi during litter decomposition

Microorganisms play a crucial role in the biological decomposition of plant litter in terrestrial ecosystems. Due to the permanently changing litter quality during decomposition, studies of both fungi and bacteria at a fine taxonomic resolution are required during the whole process. Here we investigated microbial community succession in decomposing leaf litter of temperate beech forest using pyrotag sequencing of the bacterial 16S and the fungal internal transcribed spacer (ITS) rRNA genes. Our results reveal that both communities underwent rapid changes. Proteobacteria, Actinobacteria and Bacteroidetes dominated over the entire study period, but their taxonomic composition and abundances changed markedly among sampling dates. The fungal community also changed dynamically as decomposition progressed, with ascomycete fungi being increasingly replaced by basidiomycetes. We found a consistent and highly significant correlation between bacterial richness and fungal richness (R = 0.76, P < 0.001) and community structure (RMantel = 0.85, P < 0.001), providing evidence of coupled dynamics in the fungal and bacterial communities. A network analysis highlighted nonrandom co-occurrences among bacterial and fungal taxa as well as a shift in the cross-kingdom co-occurrence pattern of their communities from the early to the later stages of decomposition. During this process, macronutrients, micronutrients, C:N ratio and pH were significantly correlated with the fungal and bacterial communities, while bacterial richness positively correlated with three hydrolytic enzymes important for C, N and P acquisition. Overall, we provide evidence that the complex litter decay is the result of a dynamic cross-kingdom functional succession

Mean decay rate constants (<i>k</i>), coefficients of determination (<i>r</i>²) describing the fit of the decay model (<i>P</i><0.05), and mean percentage of leaf remaining mass at the end of the study (473 days after incubation) under different forest system management practices.

<p>Different lower-case letters indicate significant differences according to one-way ANOVA incorporating Fisher’s Least Significant Difference.</p

Percent of initial magnesium (Mg), potassium (K), calcium (Ca) and phosphorous (P) during decomposition under different forest system management practices.

<p>Norway spruce age-class forest (blue, SA), European beech age-class forest (red, BA), European beech selective cut forest (green, BS) and unmanaged deciduous forest reserves dominated by European beech (black, BU) (mean ± SD, n = 3). Different letters indicate significant differences according to one-way ANOVA incorporating Fisher’s Least Significant Difference (from 89 DAI to 473 DAI).</p

Main characteristics of the selected forest sites in this study.

<p>Main characteristics of the selected forest sites in this study.</p

Initial chemical composition of dried leaf litter under different forest management practices (Mean±SD, n = 3).

<p>Different lower-case letters indicate significant differences according to one-way ANOVA incorporating Fisher’s Least Significant Difference.</p

C/N and total lignin/N ratios in leaf litter during 473 days of decomposition under different forest system management practices.

<p>Norway spruce age-class forest (blue, SA), European beech age-class forest (red, BA), European beech selective cut forest (green, BS) and unmanaged deciduous forest reserves dominated by European beech (black, BU) (mean ± SD, n = 3). Different letters indicate significant differences according to one-way ANOVA incorporating Fisher’s Least Significant Difference (from 89 DAI to 473 DAI).</p

Remaining amount of leaf litter dry mass, carbon, nitrogen and total lignin during decomposition under different forest system management practices.

<p>Norway spruce age-class forest (blue, SA), European beech age-class forest (red, BA), European beech selective cut forest (green, BS) and unmanaged deciduous forest reserves dominated by European beech (black, BU) (mean ± SD, n = 3). Different letters indicate significant differences according to one-way ANOVA incorporating Fisher’s Least Significant Difference (from 89 DAI to 473 DAI).</p

Information on the litter composition for individual forest sites.

<p>Information on the litter composition for individual forest sites.</p