冷冻干燥造成乳酸菌损伤的研究

检测冻干对乳酸菌造成的各种损伤,考察乳酸菌在冷冻干燥过程中的行为,从而确定造成冻干致死的原因,为冻干保护提供理论依据。实验表明,冻干后残余水分含量对冻干存活率的影响在菌株种属之间差异不大,冻干后残余水分含量在2%～4%时,冻干存活率相对较高。乳酸菌冻干前后钠钾离子比例发生显著变化,说明冻干对乳酸菌细胞膜通透性有影响。乳酸菌冻干后,Na+、K+-ATP酶的活性明显下降,说明冷冻干燥过程对细胞膜上的关键酶会造成一定的损伤。冻干后的上清液中,β-半乳糖苷酶活性显著增加,表明在冷冻干燥过程中细胞膜的通透性发生了改变,使原本细胞内的物质渗透出去。

Study on the Damage of Lactic Acid Bacteria Following Freeze Drying

We examined the damage and the behavior of lactic acid bacteria following freeze drying in order to identify the reasons for loss of viability. A brief evaluation of the damage caused by freeze drying was made to avoid it using suitable cryoprotectants. From the results, we were convinced that a certain amount of residual water content of the dry system must be left for a satisfactory survival rate, 2%～4% residual water content of the dry system is better. There is no significant difference between the strains. The freeze drying of the cell revealed a remarkable change of the Na+/K+ content, which indicated that the change of the cell penetration. The decrease of Na+、K+-ATPase activity revealed the damage of the membrane enzyme caused by freeze drying. The fact that the β-Galactosidase activity increased remarkably in the cell supernatant fluid after freeze drying showed the change of the membrane permeability, which resulted in the exit of internal constituents.