[Isolation and identification of termitarium antagonistic actinomycetes BYC 01 and its active metabolites].

Abstract

We isolated actinomyces from the termitarium and studied its metabolites to find the antimicrobial compounds. We determined the taxonomic status of target strain BYC 01 by morphological observation and 16s rRNA sequence analysis. Growth rate method and agar disc diffusion assays were used to test the antimicrobial activities. Fermentation product was isolated and purified by various chromatographic methods, and the structure was determined by mass spectrum and nuclear magnetic resonance analyses. BYC 01 was identified as Streptomyces violaceoruber. The main antimicrobial ingredients of BYC 01 fermentation broth consisted in the ethyl acetate fraction of moderate polar part. The ethyl acetate extract of BYC 01 had strong antifungal activities against Valsa mali with inhibition rate of more than 90%, and activities against Rhizoctonia solani and Dothiorella gregaria with inhibition rate of more than 60% under the concentration of 100 microg/mL. Furthermore, the extract showed the intermediate antimicrobial activities against Candida albicans, Staphyloccocus aureus, Escherichia coli, Bacillus subtilis and Xanthomonas oryzae with the mean halo diameters ranging from 11.3 to 16.5 mm under the concentration of 30 microg/filter paper. A monomer compound was purified from the fermentation products, and was identified as fogacin on the basis of mass spectrum and nuclear magnetic resonance analyses. The compound fogacin and the positive control had similar antimicrobial activities against C. albicans with inhibition zone of 19.3 mm and 20.1 mm under the concentration of 30 microg/filter paper. Strain BYC 01 could be potentially developed as a new antimicrobial agent.