Abstract
Background: Lichen is a complex symbiotic relationship arose from algae or cyanobacteria that live together with some fungal species. Some of them are edible and consumed as spice such as Platismatia glauca. The current study aimed to evaluate it's the antimicrobial properties of the methanolic extract of lichen thalli of P. glauca against some referenced bacterial and yeast strains.
Methods: Disc diffusion test, minimum inhibitory (MIC) and minimum bactericidal (MBC) or minimum fungicidal (MFC) tests were carried out to evaluate the antimicrobial activity of lichen.
Results: All tested microorganisms exhibited varying degrees of susceptibility. Among the tested strains, the most susceptible bacterium -using the disc diffusion assay- was Staphylococcus saprophyticus (18.5 +/- 1.0 mm), followed by Staphylococcus aureus (14.5 +/- 0.5 mm), Shigella flexneri (12.5 +/- 1.5 mm), Streptococcus pneumoniae (12.0 +/- 1.0 mm), Proteus vulgaris (11.5 +/- 0.5 mm), Salmonella Typhimurium (11.5 +/- 0.5 mm), Bacillus cereus (11.0 +/- 1.0 mm) and Escherichia coli (11.0 +/- 0.0 mm), respectively. It also showed high antifungal activity against Candida albicans (22.5 +/- 0.5 mm). The MIC, MBC and MFC were promising, which were as low as 3.125 to 12.5 mg/ml for MIC and 6.25 to 12.5 mg/ml for MBC and MFC.
Conclusion: From the obtained results, it is concluded that the lichen thalli of Platismatia glauca possesses a remarkable antimicrobial activity and it may be considered as a source of potential antimicrobial agents.