冷冻保护剂对直投式木葡萄酸醋杆菌发酵剂菌体细胞特性的影响

本文研究了1%谷氨酸、5%海藻糖、10%脱脂乳及复合0.575%谷氨酸+0.075%海藻糖+6.4%脱脂乳作为冷冻保护剂对直投式木葡萄酸醋杆菌(GBX)发酵剂菌体细胞特性的影响,通过测定GBX发酵剂菌体细胞的DNA泄露、细胞液总抗氧化能力、SOD活性、纤维素合成酶活性和ATP酶活性变化等情况来衡量GBX菌体细胞的生理活性变化。结果发现:添加单一1%谷氨酸、5%海藻糖、10%脱脂乳以及复合0.575%谷氨酸+0.075%海藻糖+6.4%脱脂乳作为保护剂均能明显抑制冷冻干燥过程中菌体细胞的DNA泄露,提高细胞总抗氧化能力、SOD活性、纤维素合成酶和ATP酶活性,表明添加冷冻保护剂能够一定程度上保护菌体细胞,其中复合保护剂对菌体细胞的保护效果最佳,电子扫描显微镜也验证了冷冻保护剂能确实降低菌体细胞在冷冻干燥过程中损害程度,从而使菌体细胞保持良好的生理活性。

Effects of Cryoprotectants on the Cytochemical Properties of DVS Gluconacetobacter xylinus Cells

Into DVS Gluconacetobacter xylinums cell suspension, 1% Glutamic acid, 5% trehalose, 10% skim milk, or a mixture of 0.575% glutamic acid ,0.075% trehalose and 6.4% skim milk was added as a cryoprotectant. Their effects of on the cytochemical properties of Direct-Vat-Starter (DVS) Gluconacetobacter xylinus (GBX) cells were determined and compared. Changes in the physiological activity of GBX cells was measured in terms of changes in DNA leakage, total antioxidant capacity, superoxide dismutase (SOD) activity, as well as cellulose synthase and ATP activity of the bacterial cells. The results showed that DNA leakage of the bacterial cells was reduced and total antioxidant capacity, SOD activity, cellulose synthase, and ATP synthase activities were increased by adding 1% glutamic acid, 5% trehalose, 10% skim milk or 0.575% glutamic acid + 0.075% trehalose + 6.4% skim milk as a cryoprotectant during freeze-drying process. The results indicated that the GBX cells were well protected by cryoprotectants, and the optimum protective effect was observed with the compound cryoprotectant 0.575% glutamic acid + 0.075% trehalose + 6.4% skim milk. The results from scanning electron microscopy (SEM) also verify that the various cryoprotectants could significantly reduce the damage to GBX cells during freeze-drying process, thus maintaining good physiological activity of GBX cells.