Coculture of actinomycetes with Bacillus subtilis and its effect on the bioactive secondary metabolites

Abstract:

To explore the effect of coculturing actinomycetes with Bacillus subtilis on the production of bioactive secondary metabolites, we studied the difference between fermentation products of monocultures and the corresponding cocultures of 22 actinomycetes by antimicrobial assay and HPLC-PDA analysis. We selected Streptomyces strain FXJ2.014 with high bioactivity for further analysis and found additional metabolites in fermentation extracts of cocultures of strains FXJ2.014, FXJ1.296 and AS 4.1252 respectively with B. subtilis. Quinomycin A was the main bioactive metabolite produced by the monoculture of strain FXJ2.014, while a new quinomycin-like component named FXJ2.014-HB was produced when strain FXJ2.014 was cocultured with B. subtilis. Further tests of antimicrobial and antitumor activities indicated that FXJ2.014-HB and Quinomycin A had significant differences in terms of bioactivity. Moreover, the inhibitory activity of FXJ2.014-HB to a variety of tumor cell lines was weaker than the highly toxic Quinomycin A, indicating its potential to be an antibiotic with low cell toxicity. In conclusion, coculture can be used as a promising approach to discover bioactive secondary metabolites from actinomycetes.