Production and characterization of bioactive metabolites from piezotolerant deep sea fungus Nigrospora sp. in submerged fermentation

• Published in: Journal of applied microbiology 2015, Vol.118 (1), p.99-111
• Main Authors: Arumugam, G.K, Srinivasan, S.K, Joshi, G, Gopal, D, Ramalingam, K
• Format: Article
• Language: English
• Subjects: Anti-Bacterial Agents - metabolism; Anti-Bacterial Agents - pharmacology; anti-infective properties; anticancer; anticarcinogenic activity; antimicrobial; Antineoplastic Agents - metabolism; Antineoplastic Agents - toxicity; Ascomycota - classification; Ascomycota - cytology; Ascomycota - genetics; Ascomycota - metabolism; bacteria; carbon; Cell Line, Tumor; cosmetics; cytotoxicity; Fermentation; Fourier transform infrared spectroscopy; Fungi; gas chromatography-mass spectrometry; griseofulvin; growth retardation; Humans; internal transcribed spacers; Jurkat Cells; Marine; marine environment; marine fungi; marine fungus; MCF-7 Cells; Metabolites; Microbiology; minimum inhibitory concentration; Molecular Sequence Data; mycelium; Nigrospora; pharmaceutical industry; Pressure; ribosomal RNA; salinity; Seawater - microbiology; Secondary Metabolism; secondary metabolites; submerged fermentation; sucrose; temperature; tryptophan
• ISSN: 1364-5072; 1365-2672
• DOI: 10.1111/jam.12693

AIMS: To produce and characterize bioactive metabolites from piezotolerant marine fungus Nigrospora sp. in submerged fermentation. METHODS AND RESULTS: A distinct marine strain, Nigrospora sp. NIOT has been isolated from a depth of 800 m 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 6·0–8·0 pH, 20–30°C temperature, 7·5% 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 30 μg ml⁻¹. Strongest cytotoxicity was observed in all cell lines tested, GI₅₀(growth inhibition by 50%) was calculated to be 1·35, 3·2, 0·13 and 0·35 μg ml⁻¹against 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. CONCLUSIONS: A 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 STUDY: This is the first study exploring Nigrospora sp. from 800 m 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.