ABSTRACT
Caves are special environments that harbour an incredible diversity of life, including fungal species. Brazilian caves have been demonstrated to be biodiversity hotspots for known and unknown fungal species. We investigated the richness of culturable fungi in a tropical cave in Brazil by isolating these microorganisms from the sediment and air. The fungal abundance of colony-forming units (CFUs) was 3 178 in sediment and 526 in air. We used morphological features and phylogenetic analyses of actin (actA), calmodulin (cmdA), internal transcribed spacer regions and intervening 5.8S rRNA (ITS), large subunit (LSU) rDNA, RNA polymerase II second largest subunit (rpb2), translation elongation factor 1-alpha (tef1), and ß-tubulin (tub2) genes to identify these isolates. Forty-one species belonging to 17 genera of Ascomycota and two of Basidiomycota were identified, and the genus Aspergillus was most commonly observed in the cave (13 taxa). Twenty-four species were found in sediment (16 exclusives) and 25 species were found in air (17 exclusives). In this study, we introduced a new genus (Pseudolecanicillium gen. nov.) in the family Cordycipitaceae and six new species (14 % of the total taxa identified) of fungal isolates obtained from sediment and air: Aspergillus lebretii sp. nov., Malbranchea cavernosa sp. nov., Pseudohumicola cecavii sp. nov., Pseudolecanicillium caatingaense sp. nov., Talaromyces cavernicola sp. nov., and Tritirachium brasiliense sp. nov. In addition, we built a checklist of the fungal taxa reported from Brazilian caves. Our results highlight the contribution of Brazilian caves to the estimation of national and global fungal diversity. Citation: Alves VCS, Lira RA, Lima JMS, Barbosa RN, Bento DM, Barbier E, Bernard E, Souza-Motta CM, Bezerra JDP (2022). Unravelling the fungal darkness in a tropical cave: richness and the description of one new genus and six new species. Fungal Systematics and Evolution 10: 139-167. doi: 10.3114/fuse.2022.10.06.
ABSTRACT
Opuntia ficus-indica Mill. (forage cactus) is farmed with relative success in the semi-arid region of the Brazilian northeast for commercial purposes, particularly as forage and food. Endophytic microorganisms are those that can be isolated inside plant tissues and can be a new source to production of enzymes with different potentialities. The objective of this study was to describe the richness of endophytic fungi from O. ficus-indica and to detect the capacity of these species to produce extracellular hydrolytic enzymes. Forty-four endophytic fungi species were isolated. Among them, the most commonly found were Cladosporium cladosporioides (20.43%) and C. sphaerospermum (15.99%). Acremonium terricola, Monodictys castaneae, Penicillium glandicola, Phoma tropica and Tetraploa aristata are being reported for the first time as endophytic fungi for Brazil. The majority of isolated fungi exhibited enzymatic potential. Aspergillus japonicus and P. glandicola presented pectinolytic activity. Xylaria sp. was the most important among the other 14 species with positive cellulase activity. All 24 isolates analysed were xylanase-positive. Protease was best produced by isolate PF103. The results indicate that there is a significant richness of endophytic fungi in O. ficus-indica, and that these isolates indicate promising potential for deployment in biotechnological processes involving production of pectinases, cellulases, xylanases and proteases.