Antibacterial activity of endophytic fungi isolated from mangroves of Jaffna Peninsula, Sri Lanka

Mangroves are plant communities growing in the intertidal zone of tropical to subtropical coastal rivers. Some endophytic fungi which live in the tissues of mangrove plants produce some biologically active substances. By screening these biologically active substances some researchers have found that these substances have antimicrobial activity. This research is aimed to determine the antibacterial activity of endophytic fungi isolated from leaves of mangrove plants Excoecaria agallocha, Avicennia marina, Rhizophora mucronata and Lumnitzera racemosa in Sarasalai area in Jaffna Peninsula in Sri Lanka. Various species of endophytic fungi were isolated from the leaves of mangrove plants and identified based on morphological characteristics. Five fungal species were isolated from E. agallocha four from R. mucronata, A. marina and two from L. racemosa. Fifteen endophytic fungi were tested against six selected bacteria for their antagonistic effect. Antibacterial activity was tested against Escherichia coli, Bacillus sp, Klebsiella sp, Pseudomonas sp, Staphylococcus sp. and Proteus sp. using disc diffusion assay. Almost all endophytic fungi inhibited the growth of bacteria. Aspergillus flavus had the highest amount of inhibition against E. coli, Pseudomonas and Staphylococcus sp. Aspergillus tamari had higher amount of inhibition against Klebsiella sp. Few other species of Aspergillus also showed higher inhibitory activity against different bacteria when compared to other endophytic fungi.   Key words: Mangrove, endophytic fungi, bacteria.