| Actinomycetes, especially streptomycetes are the main microbial source of bioactive natural substance and drugs, and are constantly used as typical biological materials for studying microbial growth, development and secondary metabolic functions. With its complicated morphology, distinctive metabolic pathways and diverse secondary metabolites, actinomycetes have been the key object of attention and research, showing its immense value in the fields of science, economy and society.To explore the effect of coculturing actinomycetes with Bacillus subtilis on the production of bioactive secondary metabolites and screen bioactive secondary metabolites from actinomycete strains, antibacterial activity of fermentation liquor and fermentation extracts which have good antibacterial activity from 40 actinomycete strains of different sources were studied. We also studied the HPLC spectrogram differences between the fermentation products of monocultures and corresponding cocultures of 22 actinomycetes strains by HPLC-PDA analysis, and found additional metabolites in the fermentation extracts of cocultures of strains FXJ2.014, FXJ 1.296 and AS 4.1252 respectively with B. subtilis, which were not found in monoculture of them in the same conditions.Streptomyces strain FXJ2.014 with high bioactivity was selected for further analysis of its bioactive metabolites in cocultures. By Amplified monoculture and coculture of strain FXJ2.014, extraction and separation of bioactive metabolites, we found the monoculture of strain FXJ2.014 mainly produced FXJ2.014-3 as the bioactive metabolite. By UV, ESI-MS and NMR analysis, FXJ2.014-3 was identified as Quinomycin A. While the coculture of strain FXJ2.014 with B. subtilis produced a new component named FXJ2.014-HB other than Quinomycin A. By UV, ESI-MS analysis and comparison with Quinomycin A, FXJ2.014-HB was identified as a quinomycin A-like compound.Further analysis and assay of antimicrobial and antitumor activities of FXJ2.014-HB and Quinomycin A indicated that they had significant differences in terms of bioactivity and antibacterial spectrum. The clinical application of Quinomycin A is limited because of its high cell toxicity. While the inhibitory activity of FXJ2.014-HB to a variety of tumor cell lines was weaker than Quinomycin A, indicating its potential to be an antitumor antibiotic with low cell toxicity. So FXJ2.014-HB induced by coculture provides a good compound basis for further screening of clinically efficient, low toxic and potential antitumor antibiotics.Due to the extensive and prolonged use of antibiotics, the problem of bacterial resistance to antibiotics has become more and more serious, hence it is urgent to discover and exploit anti-resistant antibiotics of novel type, high efficiency and low toxicity. As a promising way to discover new antibiotics, coculture induction method reveals a new idea for the development and utilization of existing microbial resources.
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