Isolation and screening of antimicrobial activity of endophytic fungal isolates from lemon Thai Basil (Ocimum citriodorum Vis.) leaves.

This study was aimed to screen the antimicrobial activity of endophytic fungal isolated from medicinal herb Ocimum citriodorum Vis. leaves. The healthy leaf samples with no visible of disease symptoms were collected from Kampung Kandek, Dabong Kelantan. One percent of sodium hypochlorite was used as the surface steriliant for the surface sterilization. A total of 167 endophytic fungal isolates from 0. citriodorum leaves were obtained, including 19 from young leaves, 41 from mature leaves, 65 from old leaves and 42 from senescent leaves. Result shows, the old leaves were the most densely colonized as compared with the other growth stages of the leaves. From the total of 167 endophytic fungi isolates from the different leaf age stages , 25 endophytes were isolated from PDA, 47 from PHP, 30 from PPE, 16 from MEA, 29 from MHP and 20 from MPE. Endophytic fungi were mostly growing in Potato dextrose agar with host plant as the high endophytes were isolated from this media. Overall, ten endophytes with different colonies were isolated from the total of 167 for primary screening. Two isolates, namely TLBML-M1 and TLBML-PHP2 showed the most significant antimicrobial activity on the test microorganisms which is both inhibited almost all bacteria and very effective in killing Methicillin-resistant Staphylococcus aureus, Klebsiella pheumoniae and Shigella boydii. The fungal biomass of both endophytic fungi, TLBML-M1 and TLBML-PHP2 showed a high antimicrobial compound present compared to the fermentative broth. The fungal biomass inhibited all bacteria except gram-positive Staphylococcus aureus. The ethyl acetate and dichloromethane extract showed the high antimicrobial activity present in the broth of endophyte since they inhibited almost all bacteria. This indicate that antimicrobial compound from fermentative broth can be effectively extracted by ethyl acetate and dichloromethane.