产L－乳酸的菌种的筛选及L－乳酸生产新途径

本实验以大豆秸秆酶解液为原料，发酵制备L- 乳酸。首先对产L- 乳酸的四株菌进行筛选，选出性能优良、糖利用率和乳酸产量均较高的干酪乳杆菌作为实验用菌种。然后对乳酸菌发酵大豆秸秆酶解液制备L- 乳酸的影响因素进行了研究，研究结果表明：干酪乳杆菌发酵的最佳接种量为10%，最适发酵温度为30℃，最佳pH 值为5.5；在发酵42h 时，大豆秸秆酶解液中残留糖浓度接近于零，此时，随底物浓度的增高，乳酸产量相应增加，并且酶解液浓度达到34.98g/L 时，乳酸生产没有受到抑制。

Screening of Lactobacillus casei Fermenting Enzymatic Hydrolysate of Soybean Straw for Production of L-Lactic acid and Its Fermentation Characteristics

This study aimed to produce L-lactic acid from enzymatic hydrolysis solution of soybean straw by fermentation. Lactobacillus casei was selected out from four species of Lactobacillus for producing L-lactic acid because of its good performance and high reducing sugar utilization rate and L-lactic acid yield. And its fermentation characteristics were investigated. The results indicated that the optimum temperature, inoculation size and pH are 30℃, 10% and 5.5, repectively; With sugar concentration rising, the lactic acid yield produced by Lactobacillus casei increases correspondingly. After 24-h fermentation, the residual concentration of sugar in hydrolysis solution of soybean straw is close to zero. At that time, the L-lactic acid yield increases with the substrate concentration increasing. When the substrate concentration is up to 34.98 g/L, the production of L-lactic acid is not inhibited any more.