NW-G01, produced by Streptomyces alboflavus 313, is a novel cyclic hexapeptide antibiotic with many potential applications, including antimicrobial activity and antitumor agents. This study developed a system for optimizing medium components in order to enhance NW-G01 production. In this study, Plackett-Burman design (PBD) was used to find the key ingredients of medium components, and then response surface methodology (RSM) was implemented to determine their optimal concentrations. The results of PBD revealed that the crucial ingredients related to the production of NW-G01 were (NH₄)₂SO₄, peptone and CaCO₃. A prediction model has been built in the experiments of central composite design and response surface methodology, and its validation has been further verified. The optimal medium composition was determined (g/L): corn starch 15, glucose 15, peptone 3.80, (NH₄)₂SO₄ 0.06, NaCl 1.5, CaCO₃ 1.30, MgSO₄·7H₂O 0.015, K₂HPO₄·3H₂O 0.015, MnCl₂·4H₂O 0.015, FeSO₄·7H₂O 0.015, and ZnSO₄·7H₂O 0.015. Compared with NW-G01 production (5.707 mg/L) in non-optimized fermentation medium, the production of NW-G01 (15.564 mg/L) in optimized fermentation medium had a 2.73-fold increase.

An actinomycete, isolated from soil samples of western Sichuan Plateau of China, was identified as Streptomyces alboflavus SC11 by 16S rDNA analysis, and also cultural, morphological and physiological characteristics of the strain were recorded. From the fermentation broth of the strain, an antimicrobial ingredient was isolated and elucidated as desertomycin A, mainly by analysis of electrospray ionization tandem mass spectrometry (ESI-MS/MS), 1H nuclear magnetic resonance (NMR) and 13C NMR spectra data. Desertomycin A exhibited good antimicrobial potential against the pathogenic bacteria and fungi. Minimum inhibition concentration (MIC) values of desertomycin A were 3.9, 7.8 and 7.8 μg/ml against Bacillus cereus, Bacillus subtilis and Staphyloccocus aureus,respectively. Key words: Streptomyces alboflavus SC11,Desertomycin A, 16S rDNA, Antimicrobial activities.