Estudo dos metabólitos secundários de actinobactérias dos gêneros Streptomyces (ACTB-77 e ACTB-242) e Amycolatopsis (ACTB-290) na inibição de fungos fitopatogênicos

• Ano de defesa: 2022
• Autor(a) principal: Brito, Maria Vieira de
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Palavras-chave em Português: Streptomyces; Amycolatopsis; COVs; Isocumarinas; Piericidina; Colletotrichum musae; Atividade antifúngica
• Link de acesso: http://www.repositorio.ufc.br/handle/riufc/68864

In this work we present the study of the antifungal potential of volatile and non-volatile organic compounds (VOCs) produced by actinobacterial strains from the rhizosphere of Caatinga against phytopathogenic fungi, with a special focus on Colletotrichum musae. In this study, twenty strains were selected for their ability to produce secondary metabolites with potential for growth inhibition (CI) against C. musae. In chapter one, we show the results for studies with VOCs, in which the highest potential of IC for VOCs produced by strains ACTB-77 and ACTB-290, both identified by molecular approach as Streptomyces sp. and Amycolatopsis sp., respectively. The effect of VOCs from these strains of actinobacteria on the morphological structure of hyphae of the fungus C. musae was investigated by SEM and revealed a significant deformation of the cell filaments of this fungus, especially in the case of ACTB-290. VOCs were investigated under axenic culture and co-culture conditions using combined HS-SPME-GCMS approaches, and data were analyzed by pattern recognition statistics. The majority of VOCs have been identified, representing 92-100% of the total peak areas. Linalool (38.53 ± 5.19) and geosmin (17.25 ± 2.55) were the main constituents of ACTB-77 VOCs, while dimethyl disulfide (48.49 ± 3.48) and dimethyl trisulfide (21.14 ± 3.50) were the main compounds of VOCs produced by ACTB-290. In chapter two we show the results for studies with non-volatile secondary metabolites, produced by ACTB-242 strains, identified by molecular biology as Streptomyces sp., the growth inhibition percentages for Fusarium Oxysporum, Colletotrichum brevisporum and C. musae treated with extracts produced by this strain ranged from 65 to 80%. Dereplication studies using UHPLC-MS/MS associated with molecular networks networking were used to identify compounds from the class of isocoumarins and piricidins. The exploration of minimum inhibitory concentrations (MIC) of extracts prepared without resins and with resins showed total inhibition of mycelial growth for C. musae at concentrations of 250 µg/mL, 62.5 µg/mL and 31.25 µg/mL.