Identificação filogenética e mineração genômica de linhagens do gênero Xylaria isoladas da região amazônica

Abstract

Microorganisms represent an important source of biotechnological resources, with potential applications across various sectors of society. In this context, fungi of the genus Xylaria have attracted increasing interest due to their ability to produce secondary metabolites exhibiting diverse biological activities, including antimicrobial, cytotoxic, and enzyme-inhibitory properties. However, the continued exploration of the metabolic arsenal of this group depends on accurate taxonomic delimitation of its species, as well as a comprehensive understanding of their biosynthetic potential, thereby contributing to a more efficient exploitation of these resources. Accordingly, this study aimed to identify Amazonian strains of the genus Xylaria and investigate their biotechnological potential through biological assays, genomic approaches, and integrated metabolomic analyses. To address the proposed specific objectives, the dissertation was organized into two chapters. In the first chapter, morphological and phylogenetic analyses were performed on 14 strains collected in the municipality of Presidente Figueiredo, Amazonas, Brazil, using the ITS, β-tubulin (tub2), and rpb2 markers. These analyses led to the recognition of 13 species, including ten species new to science, as well as three previously described species: Xylaria delicatula, X. oligotoma, and X. schweinitzii. Moreover, X. oligotoma is reported for the first time in Brazil. In the second chapter, 16 strains were evaluated through antagonism assays. Four strains exhibiting the highest inhibition percentages and evidence of distinct antagonistic mechanisms, including antibiosis and competition for space and nutrients, were selected for further analyses. These strains were subsequently subjected to antifungal activity evaluation of their extracts by broth microdilution, genome mining of biosynthetic gene clusters, and metabolomic characterization using ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry (UHPLC-HRMS) and Feature-Based Molecular Networking (FBMN). The results demonstrated antifungal activity against the phytopathogens Colletotrichum sp. and Pseudopestalotiopsis sp., as well as against Candida albicans. In addition, numerous biosynthetic gene clusters associated with secondary metabolite production were identified, and metabolomic analyses revealed remarkable chemical diversity among the investigated strains. Overall, these findings expand current knowledge of the diversity of Xylaria in the Amazon and reinforce the potential of this genus as a promising source of molecules with biotechnological applications.