Biochemical studies on the Natamycin antibiotic produced by Streptomyces lydicus: Fermentation, extraction and biological activities

Natamycin “polyene” antibiotic was isolated from the fermentation broth of a Streptomyces strain No. AZ-55. According to the morphological, cultural, physiological and biochemical characteristics, and 16S rDNA sequence analysis, strain AZ-55 was identified as Streptomyces lydicus. It is active in vitro against some microbial pathogens viz: Staphylococcus aureus, NCTC 7447; Bacillus subtilis, NCTC 1040; Bacillus pumilus, NCTC 8214; Micrococcus luteus, ATCC 9341; Escherichia coli, NCTC 10416; Klebsiella pneumonia, NCIMB 9111; Salmonella typhi and Pseudomonas aeruginosa, ATCC 10145; S. cerevisiae, ATCC 9763; Candida albicans, IMRU 3669; Aspergillus flavus, IMI 111023; Aspergillus niger, IMI 31276; Aspergillus fumigatus, ATCC 16424; Fusarium oxysporum; Alternaria alternata and Rhizoctonia solani. The active metabolite was extracted using chloroform (1:1, v/v) at pH 7.0. The separation of the active ingredient of the antifungal agent and its purification were performed using both thin layer chromatography (TLC) and column chromatography (CC) techniques. The physico-chemical characteristics of the purified antibiotic viz. color, melting point, solubility, elemental analysis (C, H, N, O and S) and spectroscopic characteristics (UV absorbance and IR, mass & NMR spectra) have been investigated. This analysis indicates a suggested empirical formula of C33H47NO13. The chemical structural analysis with spectroscopic characteristics confirmed that the compound produced by S. lydicus, AZ-55 is Natamycin “polyene” antibiotic.