antibacterial and antifungal activities of gelatinose and non-gelatinose lichen species

Background]despite the wide diversity of the basic growth forms (crustose, squamulose, foliose, and fruticose), all lichens have a similar internal morphology. the bulk of the lichen’s body is formed from filaments of the fungal partner, and the relative density of these filaments defines the layers within the lichen.[objectives]to continue and complete the previous study, this study was designed to assess the antibacterial and antifungal activity of different extractions of lichens.[materials and methods]acetone, methanol and aqueous extractions of the lichens, including <i>acarospora strigata</i>, <i>collema crispum</i>, <i>placidium squamulosum</i>, <i>physcia biziana</i>, <i>lecanora prophetaeeliae</i> and <i>ramalina farinacea</i>, were evaluated in vitro against seven bacterial strains (<i>escherichia coli</i> atcc1652, <i>salmonella typhi</i> atcc1679, <i>proteus mirabilis</i> atcc2601, <i>staphylococcus aureus</i> atcc1885, <i>enterococcus faecalis</i> atcc2321, <i>staphylococcus epidermidis</i> atcc2405, and <i>bacillus cereus</i> atcc13061), and two fungi (<i>verticillium dahlia</i>, <i>fusarium moniliforme</i>). the antibacterial activity was estimated via disc diffusion method and the minimal inhibitory concentration (mic) was determined via broth tube dilution method.[results]among the six tested lichens, methanol extracts of <i>p. squamulosum</i>, <i>p. biziana</i>, and <i>l. prophetaeeliae</i> showed relatively high antibacterial activities and also the acetone extraction of <i>l. prophetaeeliae</i> showed antibacterial activity against <i>s. epidermidis</i> and <i>b. cereus</i>. the bacteria were more sensitive than the fungi. the methanol extract of <i>p. squamulosum</i> showed the highest antibacterial activity; besides, the least amount of mic value was 250 mg/ml.[conclusions]it seems that the tested lichens could be effective as antibiotics; especially, in terms of drug resistance, they can be proper substitutes; but, further studies are suggested.