Judy Mathushika

Conference 2022 Poster Presentation


Project title

Antibacterial potential of the fungal crude extracts isolated from the Sri Lankan lichens


Authors and Affiliations

Mathushika. M.J1, Nanayakkara. C.M1, Weerasinghe. W.M.V.C1, Jayalal. R.G.U2

1. Department of Plant sciences, Faculty of Science, University of Colombo, Sri Lanka.
2. Department of Natural Resources, Sabaragamuwa University of Sri Lanka.




Sri Lanka is well-known for its lichen biodiversity. Bioactivities of lichen inhabiting fungi are being harnessed for applications in various areas worldwide. Due to increasing microbial resistance to commonly used antibiotics and reduced effectiveness of standard drugs, achievement of natural bioactive compounds has been paid more attention. Therefore, it is timely to explore the antibacterial potential of Sri Lankan lichen inhabiting fungi. This study was carried out to determine the antibacterial potential of fungi inhabiting the Sri Lankan lichens.


The lichens, Xanthoparmelia sp. and Pertusaria sp. were collected from Nonpareil Estate and Samanalawewa Wilderness in Sri Lanka respectively, for the study. Fungi associated with the lichens (Fx, Fp) were isolated by plating surface sterilized thallus pieces onto potato dextrose agar medium and emerging fungal tips from the plated pieces were transferred onto fresh medium to obtain pure cultures. Colony characteristics and micromorphology of the pure cultures of the fungi were also examined. Crude extracts were obtained from the fungal isolates via solvent extraction using ethyl acetate (EtOAc). Then the EtOAc extracts were screened in triplicate for antibacterial activities by agar disk diffusion assay with disks containing different disk strengths using bacteria: Escherichia coli (ATCC® 25922), Pseudomonas aeruginosa (ATCC® 27853) and Staphylococcus aureus (ATCC® 25923). Ciprofloxacin was used as the positive control for the assay.


EtOAc extract of the fungal culture isolated from Pertusaria sp. (Fp) showed antibacterial activity against all three bacteria whereas the fungal crude isolated from Xanthoparmelia sp. (Fx) showed antibacterial activities against Pseudomonas aeruginosa (ATCC® 27853) and Staphylococcus aureus (ATCC® 25923). Diameters of the inhibition zones (mm) of the antibacterial assays for both fungal crude extracts showed considerable amount of antibacterial activity when compared to the positive control Ciprofloxacin.


Therefore, the isolated fungi inhabiting the lichens Xanthoparmelia sp. and Pertusaria sp. can be suggested as good candidates for further research of screening antibacterial properties. Molecular identification of isolated fungi and the isolation of bioactive compounds should be carried out in order to get a more accurate understanding.