Abstract

Microbial fermentation has become the main method to produce target compound. In this study, a 2-Keto-D-gluconic acid (2-KGA) producing mutant strain was obtained by mutation with rational screening methods. Meanwhile, prodigiosin was produced when the nitrogen source in the medium was changed to peptone and its fermentation conditions were evaluated to achieve high-efficient accumulation. The mutant strain SDSPY-136 was firstly identified as Serratia marcescens by morphological observation and 16S rDNA sequencing. The 2-KGA synthetic capacity of S. marcescens SDSPY-136 was evaluated by shake fermentation with 110 g/L glucose as substrates. For fermentation, 2-KGA yield, conversation rate and purity of SDSPY-136 reached 104.60 g/L, 95.10%, 99.11% in 72 h. The red pigment was extracted from the fermentation broth using acidic methanol and identified as prodigiosin by FT-IR. The optimal conditions were as follows: glycerol 20 g/L, peptone 20 g/L, MgSO₄15 g/L, pH 6.0, a 2% (v/v) inoculum, 30 °C and 200 rpm of shaking culture. Eventually, prodigiosin reached a yield of 9.89 g/Lafter shake culturing for 50 h under this condition. The mutant S. marcescens SDSPY-136 was shown to be promising for 2-KGA and prodigiosin production and a suitable object for prodigiosin metabolism research of S. marcescens.

摘要

微生物发酵已成为生产目标化合物的主要方法。本研究通过合理的筛选方法进行突变，获得一株产2-酮-D-葡萄糖酸（2-KGA）的突变株。同时，将培养基中的氮源改为蛋白胨时产生灵菌红素，并对其发酵条件进行评估，以实现高效积累。通过形态学观察和16S rDNA测序，首先将突变株SDSPY-136鉴定为粘质沙雷氏菌。S. marcescens的2-KGA合成能力SDSPY-136 通过以 110 g/L 葡萄糖作为底物的摇动发酵进行评估。发酵方面，SDSPY-136的2-KGA产率、转化率和纯度在72 h内分别达到104.60 g/L、95.10%、99.11%。使用酸性甲醇从发酵液中提取红色素，并通过 FT-IR 鉴定为灵菌红素。最佳条件如下：甘油20 g/L、蛋白胨20 g/L、MgSO ₄ 15 g/L、pH 6.0、2% ( v/v )接种物、30°C和200 rpm振荡培养。最终，在此条件下摇动培养 50 小时后，灵菌红素的产量达到 9.89 g/L。该突变粘质沙雷氏菌SDSPY-136被证明是有前途的2-KGA和灵菌红素生产和的灵菌红素代谢研究的合适对象粘质沙雷氏菌.