Antimicrobial Activity of the Endophytic Fungi Isolated from the Medicinal Plant A

Abstract

Medicinal plants are the natural source of therapeutic drugs. There has been great interest shown to isolate the endophytic fungi colonizing the medicinal plant. These endophytes are residing in plants from thousands of years and are believed to be the treasure of structurally and biologically active compounds that have the antimicrobial, cytotoxic, immunomodulatory properties. These endophytic fungi are subjected to great exploration to isolate new species from which novel bioactive compounds can be extracted. In this study medicinal plants Tinospora cordifolia (Giloy) and Terminalia arjuna (arjuna) have been used for the isolation of the endophytic fungi. Also, Extracellular Polymeric Substance (EPS 1 and EPS 2) was extracted from the given isolated endophytic fungus T2. The number of fungal isolates obtained from Giloy were seventeen (G1-G17) and five (A1-A5) from Arjuna. These were tested for preliminary antimicrobial activity by agar diffusion method and final antimicrobial assay by microdilution method using cultures of E.coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Bacillus megaterium and Candida albicans. The maximum inhibition was shown by extract A amongst all the extacts of Arjuna. It showed inhibition of 63% against Pseudomonas aeruginosa, 62% Bacillus megaterium, 57% against Staphylococcus aureus,and 58% against E.coli and showed 40% against Candida albicans. Amongst the extracts from Giloy G15 showed the best activity of 48%, 61%, 59%, 60%, 45% against E.coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Bacillus megaterium and Candida albicans respectively. The isolated endophytic fungi from the bark of Terminalia arjuna exhibiting the best antimicrobial activity was further chosen for identification. The culture characteristics and microscopic features revealed that the above isolated endophytic fungus belongs to Penicillium sp. EPS was isolated from the endophytic fungus T2 obtained from Taxol plant and incubated for different time periods i.e. 15 days (EPS 1) and 20 days (EPS 2). These samples were subjected to the antimicrobial activity where EPS 1 exhibited more activity as compared to EPS 2. The reason for such activity could be that EPS are the primary metabolites secreted by the fungi during the growth phase. The metabolites secreted during this phase might have contributed to the activity of EPS1.