Endophytic microorganisms from leaves of Spermacoce verticillata (L.): Diversity and antimicrobial activity

Abstract

Article history: Received on: 21/11/2012 Revised on: 12/12/2012 Accepted on: 20/12/2012 Available online: 29/12/2012 Endophytic microorganisms from the base and top leaves of Spermacoce verticillata were isolated and the antimicrobial potential was evaluated. A total of 56 strains were isolated in pure culture, 44 fungi and 12 actinobacteria. The isolation frequency was higher in the base leaves (12.5%), when compared to the top leaves (3.05%). Among all fungi and actionobacteria identified, the majority belonged to the genus Guignardia (25%) and Microbispora (41.66%), respectively. The antimicrobial screening was firstly evaluated by agar plug assay and showed that 28.57% of the isolates presented activity mainly against gram positive bacteria Staphylococus aureus (ATCC-6538) and Bacillus subtilis (UFPEDA-16). The microorganisms that presented the best activities were then selected, evaluated in different culture media broth, and tested by disk diffusion assay using their fermented broth. The microorganisms selected for this assay exhibited antimicrobial activity mainly for Bacillus subtilis (UFPEDA-16). Since many isolates showed inhibitory activity against pathogenic microorganisms, it is suggestive that endophytic microorganisms from S. verticillata could be an interesting source to explore for bioactive metabolites and new tools need to be employed to explore the real potential of these microorganisms.