Screening of Antimicrobial Activity of Some Lichen Species in Vitro

Antimicrobial activity of the acetone-, methanoland aqueousextracts of the lichens Lecanora atra, L. muralis, Parmelia saxatilis, P. sulcata and Parmeliopsis ambigua was explored in vitro against to six species of bacteria and 10 species of fungi, by the disc-diffusion method and determination of the minimal inhibitory concentration (MIC) by the Broth tube Dilution method. The aqueous extracts of the tested lichens didn't show any antimicrobial activity on any of the test microorganisms, whereas the acetone and methanol extracts showed an activity related to the tested organisms. The bacteria were very sensitive related to the tested fungi. The strongest antimicrobial activity was found in the acetone extract of the lichen Parmelia sulcata where the least measured MIC value was 0.78 mg/ml. Generally, among the bacteria the most sensitive was the species Bacillus mycoides, and among the fungi Botrytis cinerea and Candida albicans. The bacterium Escherichia coli was resistant to all extracts of the explored lichens. Generally, all explored lichens had a relatively strong antimicrobial activity, which can be very important in treatment of numerous diseases caused by tested and similar microorganisms.