戊糖乳杆菌发酵培养基氮源条件的优化

对戊糖乳杆菌发酵培养基的氮源条件进行了优化。通过单因素实验及响应面分析优化利用木糖高产乳酸的戊糖乳杆菌发酵培养基的不同氮源组合。优化得到的牛肉膏与柠檬酸氢二铵复合的最佳组成为牛肉膏17.72 g/L,柠檬酸氢二铵1.91 g/L,得到乳酸实际最大产量42.37 g/L。添加玉米浆与酵母粉和无机氮源复合的最佳组成为玉米浆46.54 g/L,酵母粉21.95 g/L,柠檬酸氢二铵9.95 g/L,可得到乳酸最大产量41.06 g/L。通过响应面优化减少了有机氮源的种类。牛肉膏与柠檬酸氢二铵的复合得到了更高的乳酸产量,且减少了有机氮源用量,节约了成本。玉米浆与酵母粉的复合解决了单一玉米浆造成的木糖利用速率过低的问题,同样得到较高浓度的乳酸。

Condition Optimization of Nitrogen Source in Fermentation Medium for Lactobacillus pentosus

The conditions of nitrogen source in ferment medium for Lactobacillus pentosus was optimized. Different combinations of nitrogen sources were optimized using xylose through single factors experiment and response surface analyses for lactic acid high yielding L. pentosus. The best combination of beef extract and ammonium citrate dibasic was obtained as followed: 17.72 g/L of beef extract and 1.91 g/L of ammonium citrate dibasic, and practically produced 42.37 g/L of lactic acid at maximum. The best composite of inorganic nitrogen complex adding corn steep liquor and yeast powder, 46.54 g/L of corn steep liquor, 21.95 g/L of yeast powder, and 9.95 g/L of ammonium citrate dibasic, could obtained 41.06 g/L of lactic acid at the maximum production. The kinds of organic nitrogen source were reduced through response surface optimization. The higher production of lactic acid was produced using the complex of beef extract and ammonium citrate dibasic, and reduced the amount of organic nitrogen sources, and saved the cost. The complex of corn steep liquor and ammonium citrate dibasic has solved the problem of the hyper-low utilization rate of xylose caused by using corn steep liquor as single nitrogen source, still obtained higher concentration of lactic acid.