直投式乳酸菌发酵剂的研制

Development of a Directed Vat Set Starter of Lactic Acid Bacteria

本研究旨在研制出一种菌活高、使用简单,无需复杂的无菌操作技术与设备的直投式乳酸菌发酵剂,可用于发酵乳、泡菜以及动物饲料发酵和生产。本发酵剂以嗜酸乳杆菌LH1F为菌种,实验过程优化番茄汁增菌培养基的配方,细胞数目达4.25×1010CFU/mL。最佳的抗冷冻保护剂的配方为:脱脂奶粉2.5%,甘油1%,葡萄糖2.5%,蔗糖1%,Vc 2.5%。真空冷冻干燥的条件为4000 r/min,20 min离心获得菌体后真空冷冻干燥6 h。通过优化的直投式乳酸菌发酵剂的活菌数可以达到1.27×1012CFU/g;于4℃存放三个月后,乳酸菌活菌数仍达到3×1010CFU/g。因此,经过优化乳酸菌发酵条件及保护剂配方,所得的冻干型直投式菌种可用于乳品及动物饲料的发酵。

A Directed Vat Set （DVS） of lactic acid bacteria （LAB） was developed for the fermentation and production of fermented soft drink and animal feed. Lactobacillus acidophilus LH1F was used as test strain. The cultural media for the L. acidophilus LH1F growth and the ingredients of anti-freeze protectants for lyophilization of LAB cells were optimized by orthogonal tests. The highest cell concentration of 4.25×10^l0 CFU/mL was found using tomato juice enrichment medium. The optimized anti-freeze protectants recipe contained skimmed milk powder 2.5%, glycerol 1%, glucose 2.5%, sucrose 1% and Vitamine C 2.5%. After 6 hours lyophilization, the number of viable LAB cells of DVS was about 1.27× 10^12 CFU/g. The cell number still maintained 3× 10^10 CFU/g after three months preservation at 4℃.