Isolation and Characterization of Bioactive Molecules from Endophytic Fungi

Abstract

Endophytes are ubiquitous organisms residing in the internal tissues of the plants and are capable of producing a wide range of secondary metabolites with the biological activities of interest for application in environment, agriculture, medicine and food industry. In the present study, endophytic fungi were isolated from Taxus baccata and were identified based on their morphological characteristics and internal transcribed spacer of rDNA sequence analysis. The extracts of these fungi were tested for anticancer and antioxidant activities. Some of the putative compounds involved in these biological activities were identified. An attempt has also been made to examine the potential of thermotolerant endophytic fungi, isolated from the plants growing in the Western Ghats of India, to produce extracellular enzymes. A total of 25 endophytic fungi were isolated from the bark of T. baccata and screened for antimicrobial and cytotoxic activities. Among the 25 isolates, four isolates (T1, T2, T4 and T6) showed more antimicrobial and cytotoxic activities compared to other isolates. These four isolates were selected for further studies. Further, these isolates were identified based on their morphological characteristics and internal transcribed spacer (ITS) sequence analyses. Based on the morphological and ITS sequence analysis, isolate T1 was identified as Diaporthe sp., isolate T2 as Marasmius scorodonius, isolate T5 as Microdiplodia sp. and isolate T6 as Fusarium tricinctum. The effect of these fungal crude extracts were tested on the growth of bacteria such as Staphylococcus aureus, Bacillus megaterium, Escherichia coli and Pseudomonas aeruginosa and Candida albicans. These isolates showed antibacterial and antifungal activities. The effect of crude fungal extracts on the growth of cancer cell lines was evaluated by MTT assay.