Bioactivities of Endophytic Actinomycetes from Selected Medicinal Plants in the World Heritage Site of Saint Katherine, Egypt

摘要

Endophytic actinomycetes were isolated from surface-sterilized living aerial parts of four medicinal plant s, Artemisia herba-alba , Echinops spinosus, Mentha longifolia and Ballota undulate . A simplified method for selective recovery of actinomycetes from internal plant tissues is described. Successful recovery was achieved on the media: starch casein agar, 1/10 diluted starch casein agar, tap water yeast extract agar and MG-plant extract agar. A total of 41 isolates were obtained, belonging to different genera with a prevalence of Streptomyces ; tentatively identified according to microscopic examination and amino acid composition of the whole cell hydrolystates. The highest number of isolates was recovered from Mentha longifolia and represented 34% of the isolates. Organic extracts of all cultures were assayed for cytotoxicity against Artemia salina and for antimicrobial activities against 4 reference bacterial strains, 6 clinical bacterial cultures and two clinical fungal cultures. Variable activities were obtained with different actinomycete isolates; the highest activity was against the clinical culture Gardnerella vaginitis and the reference strain Shigella boydii ATCC 9207, being represented in 29% of the isolates in both cases. For the first time, the isolation of actinomycetes from Saint Katherine wild plants is reported and their potential use as novel source of bioactive compounds is discussed.