Endophytic Actinomycetes from Miconia albicans (Sw.) Triana (Melastomataceae) and Evaluation of Its Antimicrobial Activity

The need for new and useful compounds to provide assistance and relief in all aspects of human condition is over-growing. Seeking to improve the quality of life, the natural products isolated from endophytic microorganisms are important to obtain new compounds that can be used in different industrial segments. The substances formation is coupled with the onset of development of the microorganisms and the use of parvome to find novel compounds from unique habitats is a new goal. In this scope, this study aimed to isolate potentially bioactive substances produced by endophytic microorganisms collected from endemic medicinal plants. Miconia albicans (Sw.) Triana (Melastomataceae) were collected in Brazilian Tropical Savannah and disinfected. Gram-positive, catalase-positive, not alcohol-acid-resistant and spore-forming microorganisms were isolated and characterized by phenotypic analyzes. From such characteristics the isolates were characterized as actinomycetes belonging to the genus Streptomyces. Two of the isolates were identified as Nocardiopsis dassonvillei and Amycolatopsis orientalis based on the analysis of 16S rRNA gene sequences reporting, for the first time, the association of endophyticactinomycetes with aerial parts of Miconia albicans. The bioactivity was determined by testing for antibiosis using Staphylococcus aureus (ATCC 29213), Serratiamarcensis (ITB 1475), Enterococcus faecalis (ATCC 29212), Candida albicans (ATCC 10231), Escherichia coli (ATCC 25922) and Shigella sonnei (ATCC 1578) as indicator organisms. Amycolatopsis orientalis showed the best antimicrobial potential, verified by antagonist halos against S. aureus, E. faecalis, C. albicans and S. sonnei measuring 3.50 cm, 3.15 cm, 3.35 cm and 3.20 cm in diameter, respectively. These findings can contribute to the discovery and characterization of new and useful antimicrobial substances with possible medical and/or industrial applications.