Evaluation on Antimicrobial Activity of The Lichen Pleurosticta acetabulum

In this study, the ethanol extract of the lichen Pleurosticta acetabulum (Neck.) Elix amp; Lumbsch (Parmeliaceae) was investigated for their antimicrobial activity against various microorganisms by the disc diffusion method. Mycobacterium smegmatis CCM 2067, Micrococcus luteus CCM 169, Staphylococcus aureus ATCC 6538P, Proteus vulgaris ATCC 8427, Pseudomonas aeruginosa ATCC 27853, Listeria monocytogenes ATCC 15313, Klebsiella pneumoniae UC57, Bacillus cereus ATCC 7064, Escherichia coli ATCC 10536, Rhodotorula rubra DSM 70403, Candida albicans ATCC 10231 and Kluyveromyces fragilis ATCC 8608 were used as test microorgams. We have found that the ethanol extract of the lichen has a potential antimicrobial effect against all tested microorganisms, forming inhibition zones between 12.6-22.4 mm, as compared with the standard antibiotics. Notably, the extract has a strong effect against Escherichia coli and Staphylococcus aureus, especially Candida albicans. In conclusion, P. acetabulum may assist in the discovery of new antimicrobial agents that can serve as selective agents or in the preparation of new combined therapeutic drugs. However, the effect of this lichen species on more pathogenic organisms should be investigated and further and detailed pharmacological and toxicological studies should be conducted.