Bacillus amyloliquefaciens induces production of a novel blennolide K in coculture of Setophoma terrestris

Abstract

The discovery of known bioactive chemical leads from microbial monocultures hinders the efficiency of drug discovery programmes. Therefore, in recent years, the use of fungal-bacterial coculture experiments has gained considerable attention due to their ability to generate new bioactive leads. In this work, fungal strain Setophoma terrestris was cocultured with Bacillus amyloliquifaciens to discover novel bioactive compounds. The bioactive methanolic coculture extract was chosen for the isolation of compounds by chromatographic methods. The isolated compounds were characterized by NMR and mass spectrometric techniques. Coculture extract has resulted in the production of five blennolides. The novel compound, blennolide K was found active against PC-3 (prostate) and MCF-7 (breast) cell lines with an IC50 value of 3·7±0·6 and 4·8±0·4μmoll-1 respectively. Furthermore, the nuclear morphology study in PC-3 cells after treatment with blennolide K, demonstrated chromatin condensation, formation of apoptotic bodies and shrinkage of cells. To our knowledge, only few studies have reported the induction of bioactive compounds by coculture having long-distance inhibition morphology. This is principally due to the low occurrences of such morphology. Our study demonstrates the impact of coculture on production of new chemical leads in drug discovery programmes.