School of Bioscience and Biotechnology, University of Jinan, Jinan, China.
School of Bioscience and Biotechnology, University of Jinan, Jinan, China.
Int J Biol Macromol. 2019 Feb 15;123:521-530. doi: 10.1016/j.ijbiomac.2018.11.061. Epub 2018 Nov 13.
A melanin-producing strain was identified as Streptomyces sp. ZL-24 by phylogenetic analysis of 16S rRNA gene sequences. Based on single factor experiment, NiCl, FeSO and soy peptone were selected as significant variables of melanin production. Subsequent biochemical and RT-qPCR analyses revealed that melanin production was markedly driven by moderate levels of ferrous and nickel ions. The central composite design indicated that the optimal medium was composed of 3.05 mM NiCl, 1.33 g/L FeSO and 20.31 g/L soy peptone. The maximum production of the insoluble melanin (189.90 mg/L) was obtained using 3% (v/v) inoculation size in the medium of pH 7.0 at 30 °C for 5 days. Under this optimal condition, an indigenous plate culture system was standardized and used to produce soluble melanin. The resulting pure melanin pigment was up to 4.24 g/L, which set a new record of soluble melanin production. Bioactivity assay in vitro showed that both melanin pigments had strong antimicrobial, anti-biofilm and antioxidant activity. To our best knowledge, the results provide novel data on soluble melanin production, and identify an excellent candidate for anti-biofilm application.
通过 16S rRNA 基因序列的系统发育分析，鉴定出一种产黑色素的菌株为链霉菌属 ZL-24。基于单因素实验，选择 NiCl、FeSO 和大豆蛋白胨作为黑色素产生的显著变量。随后的生化和 RT-qPCR 分析表明，黑色素的产生明显受到亚铁离子和镍离子的适度水平驱动。中心复合设计表明，最佳培养基由 3.05 mM NiCl、1.33 g/L FeSO 和 20.31 g/L 大豆蛋白胨组成。在 pH 7.0 的培养基中，以 3%（v/v）的接种量在 30°C 下培养 5 天，可获得最大的不溶性黑色素（189.90 mg/L）产量。在这种最佳条件下，标准化了一种本土平板培养系统来生产可溶性黑色素。得到的纯黑色素色素高达 4.24 g/L，创下了可溶性黑色素生产的新纪录。体外生物活性测定表明，两种黑色素均具有很强的抗菌、抗生物膜和抗氧化活性。据我们所知，这些结果提供了关于可溶性黑色素生产的新数据，并确定了一种用于抗生物膜应用的优秀候选物。
