Bioprospecting of secondary metabolites produced by endophytic actinomycete isolated from Aloe vera

Abstract

The aim of this work to evaluate the antibacterial action of secondary metabolites produced by endophytic actinomycetes, against isolates of medical interest. For such, the bacteria were isolated from the botanical sample and classical morphological identification was performed. The induction of metabolites production was carried out using the Submerged Fermentation technique, followed by purification of the extract. The evaluation of antibacterial activity was accomplished by using agar diffusion and Minimum Inhibitory Concentration (MIC) assays. Macro and microscopic analysis of the grown microorganism allowed it to be identified as belonging to the genus Streptomyces. Test results demonstrated that the extract was able to inhibit the growth of C. propinquum 431024, with an inhibition zone of 27±0 mm and of C. propinquum 36063, with an inhibition zone of 24±0 mm and MIC of 32.1 µg/mL for boths. The evaluation of biofilm formation resulted in: C. propinquun 421024 as a weak producer and C. propinquun 36063 as a moderate producer. The biofilm interference test showed that compared to the control there was a reduction in biofilm formation of 22% for C. propinquun 421024, as well as a reduction in pre-formed biofilm of 27%. There was a 48% reduction in the formation and 42% in the pre-formed biofilm of C. propinquun 36063. Lastly, it was concluded that the secondary metabolites produced by the endophytic actinomycetes demonstrated an antibiotic potential against clinical strains (nasopharynx) of Corynebacterium propinquum, a rare pathogen described for causing infections in patients with pulmonary involvement, pleural effusion, bacteremia and endocarditis and which presents an emerging antibiotic resistance.