Identification and fermentation optimization of a marine-derived Streptomyces Griseorubens with anti-tumor activity

摘要

The purpose is an attempt to investigate a potential anti-tumor actinomycete WBF9 isolated from Chinese marine sediment. MTT assay was firstly used to evaluate anti-tumor activity and ID_(50) value was defined as dilution fold of fermentation broth (FB) that caused 50% inhibition of cell growth. The results reveal its strong anti-tumor activity against Hela, KB and SMMC7721 cells with the ID_(50) values of 750.3, 921.2 and 803.5, respectively. The strain was identified as Streptomyces griseorubens according to the 16S rRNA gene sequence analysis, along with the morphological, physiological and biochemical characteristics. The present study also reveals the strain WBF9 required natural seawater for good growth and production of anti-tumor metabolites. This implies some degree of marine adaptation of the strain. The one-factor-at-a-time method was used to investigate the enhanced anti-tumor activity of nutrients. The concentration of the four nutritional components was optimized by the orthogonal matrix method. The effects of the nutritional components for improving anti-tumor activity were found to be in the order of CaCl_2＞potato extract＞yeast extract＞glucose and the optimal concentrations were determined as glucose (1% w/v), potato extract (15% w/v), yeast extract (0.6% w/v) and CaCl_2 (0.12% w/v). With the optimized medium, ID_(50) value of FB reached the maximum level of 1946.8 in 1-1 flask after 7d of fermentation, which was 2.1-fold higher than that with the basal medium. It indicated a significant increase of anti-tumor activity of FB. The ethyl acetate extract was preliminarily isolated and the resulting four fractions showed anti-tumor activity. The initial identification data demonstrated that active fractions contained alkaloid, terpene, peptide, and indican. The strain of Streptomyces griseorubens being isolated from the sea was firstly reported here, and its anti-tumor activity was initially investigated in this paper.