【摘要】 在静置、搅拌及通气搅拌3种不同控氧条件下,分别用干酪乳杆菌Lactobacillus casei B3发酵及全细胞转化合成了苯乳酸,考察菌体生长、葡萄糖消耗及其发酵与转化合成苯乳酸的规律。结果表明:在转速100 r/min的搅拌条件下,L.casei B3发酵合成苯乳酸的浓度比静置发酵条件下提高了41.4%;但在空气流量2 L/min及转速100r/min的通气搅拌下,发酵合成苯乳酸的浓度较静置发酵时下降了60.3%;以8 g/L苯丙酮酸为底物,以相应静置、搅拌及通气搅拌条件下所得的菌体为全细胞催化剂转化合成苯乳酸,其摩尔转化率分别为67.2%、62.7%和35.9%。此结果说明:适度的搅拌促进了发酵过程的底物和产物传质,但充足或过量供氧会影响细胞内的转化合成酶系,不利于苯乳酸的全细胞转化合成。更多还原

【Abstract】 Phenyl lactic acid was produced by microbial fermentation and whole-cell biotransformation using Lactobacillus casei B3 under different oxygen control conditions,i. e.,the static culture,the agitation,and the aeration-agitation fermentations.Cell growth and glucose consumption were studied. The concentration of phenyl lactic acid was 41. 4% higher in the agitation at the speed of 100 r/min,but60. 3% lower in the aeration-agitation at the speed of 100 r/min and aeration rate of 2 L/min than that in the static culture.Using phenyl pyruvic acid of 8 g/L as substrate,the molar conversion ratios for phenyl lactic acid with the cells from the static culture,the agitation,and the aeration-agitation processes as the whole-cell catalysts,were 67. 2%,62. 7% and 35. 9%,respectively. The results indicated that the mass transfer of substrate and product was enhanced by the suitable agitation,while the activities of key conversion enzymes within the cells could be influenced by the enough oxygen supply regarding the aeration-agitation,and thus was negative to the whole-cell transformation.更多还原