| Congresso Brasileiro de Microbiologia 2023 | Resumo: 122-2 | ||||
Resumo:The São Pedro and São Paulo Archipelago (ASPSP) is located approximately 1.000 km off the coast of Brazil and belongs to the State of Pernambuco. The ASPSP is known for its remarkable biodiversity, which is fostered by its geographic isolation, nutrient enrichment of the waters, and its significance as a migratory route for various fish and bird species. The Archipelago is characterized as an extremophile environment due to its high temperatures, low nutritional availability and the presence of highly saline waters. During the ocean expedition to ASPSP, a comprehensive study was conducted on the microorganisms isolated from different environmental samples such as sediment and water. Among the microorganisms isolated, 154 are yeasts that represent the largest percentage of isolates, with 54 being black yeasts. Black yeasts are dematiaceous fungi characterized by thick and melanized cell walls. They exhibit a dimorphic life cycle, existing in both yeast and mycelial stages and are classified under the phylum Ascomycota. This study aims to investigate the microbiological and metabolic diversity of black yeasts in ASPSP, molecularly identify the isolates, explore their interactions with other organisms inhabiting the archipelago and understand the impact of external factors specific to this extremophile environment on the diversity of microorganisms present. From the isolates of the ASPSP, a subset of 27 yeasts were selected, of which 15 already had their Internal Transcribed Spacer (ITS) regions sequenced. The ITS sequences were processed using the Phylogeny.fr tool, employing the "One Click" configuration, enabling the construction of three phylogenetic trees using the ITS sequences of the 15 isolates, each representing a different genus. Microscopic evaluation of the yeasts' morphologies and reproductive structures was performed using a combination of Gram staining and microculture techniques. To determine whether the yeasts isolated in this environment form biofilms a experiment was performed using 2% crystal violet. Furthermore, a melanization assay was conducted using a minimal medium, supplemented with L-DOPA, to understand their capacity to metabolize L-DOPA and enhance melanization. The phylogenetic trees constructed based on the ITS sequences demonstrated the close proximity between the isolates of the Neodevriesia and Hortea genera, while also highlighting the significant phylogenetic distance between the isolates of the species Exophiala dermatitidis and Exophiala spinifera. Characteristic structures of the analyzed species were observed, such as conidiophores, conidia, septate, branched, and moniliform hyphae, as well as chlamydospores and toruloid hyphae. Thirteen black yeasts tested formed biofilms, indicating their importance for survival in the ASPSP. However, they did not metabolize L-DOPA, suggesting a different metabolic strategy. These findings emphasize the morphological characteristics of black yeasts, enabling their survival in extreme environments. They also provide insights into microbiological diversity among microrganisms from ASPSP and enhance our understanding of ecological dynamics within the archipelago, contributing to the knowledge of extremophile microorganisms and their adaptations.
Palavras-chave: São Pedro São Paulo Archipelago, black yeast, biofilm, extreme marine habitats Agência de fomento:Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Conselho Nacional de Pesquisa e Desenvolvimento (CNPq); Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul (FAPERGS) | |||||