AimsTo produce and characterize bioactive metabolites from piezotolerant marine fungus Nigrospora sp. in submerged fermentation. Methods and ResultsA distinct marine strain, Nigrospora sp. NIOT has been isolated from a depth of 800m at the Arabian Sea. The 18S rRNA and internal transcribed spacers (ITS) analysis demonstrates its close association with the genus Nigrospora. Effect of pH, temperature, salinity, carbon source and amino acids was studied to optimize the fermentation conditions. Optimal mycelia growth and secondary metabolites production were observed at 60-80pH, 20-30 degrees C temperature, 75% salinity, sucrose as carbon source and tryptophan as amino acid source. The extracellular secondary metabolites exhibited high antimicrobial activities against both gram-positive and gram-negative pathogenic bacteria with minimal inhibitory concentration (MIC) values higher than 30gml(-1). Strongest cytotoxicity was observed in all cell lines tested, GI(50) (growth inhibition by 50%) was calculated to be 135, 32, 013 and 035gml(-1) against U937, MCF-7, A673 and Jurkat, respectively. Fourier transform infrared spectroscopy (FTIR) and gas chromatography-mass spectrometry (GC-MS) analyses of secondary metabolites confirmed the production of antimicrobial and anticancer substances. ConclusionsA piezotolerant fungus Nigrospora sp. NIOT isolated from deep sea environment was successfully cultured under submerged fermentation. The secondary metabolites produced from this organism showed potent antimicrobial and anticancer activities with immediate application to cosmetics and pharmaceutical industries. Significance and Impact of the StudyThis is the first study exploring Nigrospora sp. from 800m in marine environment. This deep sea fungus under optimized culture conditions effectively produced bioactive secondary metabolites such as griseofulvin, spirobenzofuran and pyrone derivatives at higher concentrations.