基因组改组鼠李糖乳杆菌生产L-乳酸发酵培养基的优化

Optimization of Fermentation Medium Composition for L-lactic Acid Production by Genome-shuffled Lactobacillus rhamnosus

通过单因素试验确定了耐酸性强、高产L-乳酸的改组菌株Lc-F34的发酵最适碳源为葡萄糖、初始葡萄糖浓度为90～110g/L,淀粉葡萄糖水解物可以作为乳酸发酵的碳源;最适氮源为酵母抽提物,玉米浆次之,玉米浆可以部分或全部代替酵母抽提物作为乳酸发酵的氮源;适量的MgSO4和MnSO4对该菌株的发酵有刺激作用,MgSO4最适浓度为0.3%,MnSO4最适浓度为0.05%。

The optimal carbon source in the fermentation medium for L-lactic acid production by an acid-resistant and high L-lactic acid-producing strain （Lc-F34） of genome-shuffled Lactobacillus was determined to be glucose with an initial concentration range of 90- 110 g/L by one-factor-at-a-time method and starch hydrolysates also could be used as carbon source. In addition, the optimal nitrogen source was determined to be yeast extract, followed by corn steep liquor, which was able to partially or completely replace yeast extract. Furthermore, moderate addition of MgSO4 · 7H2O or MnSO4 could stimulate L-lactic acid fermentation with optimal concentrations of 0.3% and 0.05% respect to each.