Screening, identification and pigment characteristics of actinomycin D-producing actinomycetes from Purple soil in Sichuan Basin

Abstract

Abstract Background Natural pigments from microbial sources is a type of compounds with various structures and a wide range of uses, which is already an important source of antibiotic production. Results In this research, a yellow pigment-producing actinomycete was screened from purple soil in Sichuan Basin, PRC. According to the morphological, physiological and biochemical characteristics and 16s rDNA molecular sequence, the strain LS-2 was identified as Streptomyces parvulusand named as LS-2. The pigment was purified by column chromatography and showed excellent antibacterial activity against Escherichia coli (G-) and Staphylococcus aureus (G+). Through the analysis of UV-vis absorption spectrum, infrared absorption spectrum (IR) and liquid chromatography-mass spectrometry (LC-MS) , the yellow pigment was identified as actinomycin D. To increase the fermentation yield of actinomycin D, the factors affecting the fermentation system were optimized, such as basic culture medium, culture temperature, culture pH, and inoculation amount. It was found that 14% inoculum was the optimal fermentation culture system in Gause’s synthetic medium of pH=6.5 at 34 ℃. Conclusions In this research, a yellow pigment-producing strain was screened from purple soil in Sichuan Basin, PRC. Based on the results of molecular sequencing and physiological characteristics analysis, strain LS-2 was identified as Streptomyces parvulus, which is likely to be a new strain that has not been published. The fermentation production was purified by column chromatography, and the yield of pigment was about 540 mg/L. The results of spectral analysis showed that the yellow pigment produced by the strain was actinomycin D, and itshowed excellent and extensive antibacterial activity against Staphylococcus aureus (G+) and Escherichia coli(G-).