Endophytic Bacteria with Potential Antimicrobial Activity Isolated from Theobroma cacao in Brazilian Amazon

Endophytic bacteria inhabit plant tissues without damaging them and have specialized adaptation capabilities that allow them to establish themselves in this ecological niche. Endophytes produce numerous secondary metabolites with antimicrobial, anticancer, and pesticide properties, among others. In this study, endophytic bacteria were isolated and characterized from cocoa plants in a Brazilian municipality, with the view to evaluate their potential antagonistic activity on clinical bacterial strains. The isolates were identified through phenotypic analysis and molecular characterization. After bacterial isolation, it was possible to verify the presence of 11 different endophytic strains, with a bacterial load of up to 6.3 × 10³ CFU/g in each plant. The morphological and biochemical profile of the isolates varied. At the taxonomic level, these bacteria showed 99% similarity with the genera Microbacterium, Curtobacterium, Pseudomonas, Bacillus, Ralstonia, and Methylobacterium. The strains of the phylum Actinobacteria, which are known for producing natural bioactive compounds with high biotechnological potential, were effective in inhibiting Staphylococcus aureus ATCC and multidrug-resistant clinical strains. This work aims to expand knowledge about endophytes, with the aim of applying them in other sectors, such as the production of compounds against resistant human pathogens.