Diversity and Anti-microbial Activities of Actinomycetes Associated with Three Species of Lichens

Abstract

In order to find new actinomycete resources for discovering new drug leads, the actinomycete associated with lichens was studied. Three species of lichen samples were collected from 3 locations of Yunnan. Actinomycetes in the samples were isolated with 11 media, and identified with 16S rRNA gene sequence procedures. Bacteria of two of the three species were sequenced by using 454 pyrosequencing. The results of both pure culture and 454 pyrosequencing were analyzed and compared. Anti-microbial activities of pure cultural strains were determined with agar diffusion methods. 17 genera of actinobacteria were isolated and identified from Lepraria yunnaniana, and 10 genera of them were exclusive. 12 genera were isolated and identified from Punctelia borreria, and 4 genera of them were exclusive. 11 genera were isolated and identified from Parmotrema austrosinense, and 5 genera were exclusive. Total 28 genera were isolated and identified from the three lichens. Streptomyces, Rhodococcus and Nocardia were distributed widely in the three species of lichens. The results from 454 pyrosequencing revealed total 567 taxa of bacteria were detected; the phylum actinobacteria of them had 107, and was 19%. The phylum Actinobacteria from Lepraria yunnaniana had 99, and from Punctelia borreri had 92. Taxonomic positions of 33 taxa belonging to the phylum Actinobacteria were not identified by using the method. These results showed that the diversity of actinomycetes associated with the three lichens was complex and different from each other. 20%, 19%, 12%, 17%, 9%, and 11 % actinomycete strains had anti-microbial activities against Bacillus subtilis subsp. Subtilis, Staphylococcus aureus subsp. Aureus, Escherichia coli, Pseudomonas aeruginosa, Mycobacterium tuberculosis and Candida albicans respectively. There are 30,000 species of lichens on the earth. Diversity of lichen-associated actinomycetes was very rich, and the anti-microbial activities were higher. Therefore lichen-associated actinomycetes are an important source for discovering new drug leads.