Impact of Ecological Factors on the Occurrence and Spatial-Taxonomic Structure of Keratinophilic Fungi and Their Co-Occurrence in Arable Soils

Justyna Bohacz,Grzegorz Siebielec,Michał Możejko,Teresa Korniłłowicz-Kowalska

doi:10.3390/agriculture12020194

Justyna Bohacz, Grzegorz Siebielec + Show 2 more

Open Access

https://doi.org/10.3390/agriculture12020194

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Abstract

Fungi that decompose keratinized animal remains are an important component of the arable soil microbiome. The aim of the study is to characterize the communities of keratinophilic and co-inhabiting (non-keratinophilic) fungi in four cultivated soils that differ in physico-chemical properties, with particular emphasis on granulometric fractions, which have so far been omitted from studies concerning the ecology of these micromycetes. Fungi were isolated using the keratin-baiting method. Fungal species identification was carried out on the basis of their macro- and micromorphological features. The Simpson diversity index and Marczewski–Steinhaus similarity index were calculated for precise determination of the relationships between fungal communities. In the studied soils, Trichophyton ajelloi and Ctenomyces serratus dominated among keratinophilic fungi, while Purpureocillium lilacinum and Metacordyceps chlamydosporia, from the orders Eurotiales and Hypocreales, were dominant among non-keratinophilic fungi. The frequency of keratinophilic fungi was significantly positively correlated with pH and the content of two granulometric fractions, as opposed to non-keratinophilic fungi. This was reflected in the higher growth rates of keratinomycetes in loamy soil, chernozem, and rendzina, i.e., soils with a higher content of silt and clay fractions compared to sandy soil characterized by a high content of sand fractions. The species composition of both groups of fungi was most similar between loamy soil and chernozem, whereas the greatest differences were found for sandy soil and rendzina. Chernozem was characterized by the highest diversity of fungal species from both groups of fungi. The study, in addition to providing information about ecological factors, provided a collection of keratinomycete strains that can be used as a starting material for subsequent research stages regarding keratinolytic activity of these fungi and their potential use in agricultural practices.

Highlights

Fungi that colonize and decompose animal remains rich in keratin, i.e., proteins with high nitrogen and sulfur content, are present in various environments
In comparison to other soil types, loamy soil was characterized by a higher taxon richness of non-keratinophilic fungi co-occurring with keratinomycetes (Table 2)
The experiments conducted in this study showed the lowest frequency of keratinophilic fungi in sandy soil and the highest frequency in chernozem

Summary

Introduction

Fungi that colonize and decompose animal remains rich in keratin, i.e., proteins with high nitrogen and sulfur content, are present in various environments. Surface and deep soil layers containing keratin matter, most often the hair of small mammals (mainly rodents), bird feathers, and other keratinized animal remains, are the largest reservoirs and natural habitats of these fungi [1,2,3,4,5,6,7,8]. Keratinophilic fungi play a key role among these organisms This ecological Ascomycota group specializes in the decomposition of native keratin. The group comprises the so-called geophilic dermatophytes and related fungi from the Chrysosporium group [10,11]. They are saprotrophs, but some, e.g., Microsporum gypseum (Nannizzia gypsea), are potentially pathogenic to humans and animals as they can cause skin mycoses [10]

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