In vitro antimicrobial potentials of endolichenic fungi isolated from thalli of Parmelia lichen against some human pathogens

This study was undertaken to isolate and evaluate antimicrobial potentials of endolichenic fungi colonizing lichen thalli of Parmelia sp. A total of 19 distinct endolichenic fungi were obtained from surface sterilized fragments of Parmelia thalli. The dominant fungi belonged to genera Phomopsis, Aspergillus, Penicillium and mycelia sterilia. The colonization frequency of mycelia sterile (47.4%) was found to be the highest. The result indicated that 10.52% of the isolates showed antimicrobial activity against all the test pathogens in varying degrees, while 31.57% and 10.52% of the isolates displayed antibacterial and antifungal activity inhibiting all bacterial and fungal pathogens respectively. Among the isolates, species of Aspergillus and Cytospora and two sterile isolates showed considerable antimicrobial activity. These isolates were cultured in different media and incubation periods for optimum metabolites production. The crude metabolites of the isolates showed significant antimicrobial activity against all the test pathogens. Analyses of the crude metabolites by Thin Layer Chromatography and spectrophotometer study showed presence of bioactive components. The study suggests that endolichenic fungi colonizing lichen thalli may be a source of potential antimicrobial agents.