Antimicrobial activities of different extracts of Lecanora atra, Lecanora muralis, Parmelia saxatilis, Parmelia sulcata and Parmeliopsis ambigua

The antimicrobial activity of acetone, methanol and aqueous extracts of the lichens Lecanora atra, Lecanora muralis, Parmelia saxatilis, Parmelia sulcata and Parmeliopsis ambigua were tested in vitro against six species of bacteria and 10 species of fungi using the disk-diffusion method and by determining the minimal inhibitory concentration (MIC) by broth tube dilution method. The following sorts of microorganisms were tested: Bacillus mycoides, Bacillus subtilis, Staphylococcus aureus, Enterobacter cloaceae, Escherichia coli, Klebsiella pneumoniae, Aspergillus flavus, Aspergillus fumigatus, Botrytis cinerea, Candida albicans, Fusarium oxysporum, Mucor mucedo, Paecilomyces variotii, Penicillium purpurescens, Penicillium verrucosum, Trichoderma harsianum. Aqueous extracts of the investigated lichens showed no antimicrobial activity against any of the test organisms, whereas acetone and methanol extracts showed antimicrobial activity. The tested bacteria were more sensitive than the tested fungi. The strongest activity was recorded for the acetone extract of Parmelia sulcata, which had the lowest measured MIC value (0.78mg/mL). Currently, Bacillus mycoides was the most sensitive of the tested bacterial species, while Botrytis cinerea and Candida albicans were the most sensitive fungal species.