Antitumour compounds from a saline soil isolate, Streptomyces griseoincarnatus CTF15

Abstract

A new actinomycete strain designated as Streptomyces sp. CTF15 was isolated from a saline soil using casein–KNO₃ agar medium. The strain Streptomyces sp. CTF15 exhibited promising antimicrobial activity against Staphylococcus aureus, Bacillus subtilis, Streptomyces viridochromogens Tü57 and high cytotoxicity (91.2% mortality) against Artimia salina in biological screening. The cultivation of this strain in a 50 L lab fermenter and subsequent isolation and purification by a series of chromatographic techniques and structure elucidation by MS and NMR analysis of the active metabolites revealed that it is a highly stable producer of resistomycin (1), tetracenomycin D (2) and actinomycin D (3), even under non-optimised culture conditions. The morphological, microscopic, biochemical and physiological characterisation suggested that the strain CTF15 belongs to the genus Streptomyces. A partial 16S rRNA gene sequence (1429 bp) from the strain CTF15 was determined and found to have high identity (99%) with Streptomyces griseoincarnatus. As such, this is the first report of a strain of S. griseoincarnatus capable of producing these three bioactive compounds simultaneously.

Keywords:

• resistomycin
• tetracenomycin D
• actinomycin D
• Streptomyces sp. CTF15

Acknowledgements

We thank Prof. Dr Hartmut Laatsch, Institute of Organic and Biomolecular Chemistry, University of Gottingen, Germany, for providing, fermentation, MS and NMR analysis facilities. Financial support of this study by a grant from the Higher Education Commission (HEC) of Pakistan under IRSIP is gratefully acknowledged.

Notes

Both authors contributed equally to this work.

Additional information

Notes on contributors

Imran Sajid

Both authors contributed equally to this work.