NaCl刺激对乳杆菌冻干存活率及胞内磷酸果糖激酶的影响

Effect of NaCl stimulation on the survival rate of freeze-dried cells and intracellular phosphofructokinase in Lactobacillus

摘要:

NaCl刺激影响保加利亚乳杆菌磷酸果糖激酶(PFK)活性及其冻干存活率。在对数期末期保加利亚乳杆菌液中添加2% (W/V) NaCl刺激2 h后, 收获菌体, 其冻干存活率明显提高。同时采用反相高效液相色谱法(RP-HPLC)对NaCl刺激后的保加利亚乳杆菌胞内PFK活性变化进行测定, NaCl刺激使PFK活性显著增加。利用半定量RT-PCR法对NaCl刺激后PFK基因mRNA表达水平进行了比较和分析, NaCl刺激后冻干前PFK基因的表达量增加, 冻干后表达量基本无变化。NaCl刺激能够提高保加利亚乳杆菌的冻干存活率, PFK可能影响保加利亚乳杆菌的存活。

关键词:保加利亚乳杆菌, 冷冻干燥, NaCl刺激, 磷酸果糖激酶, 半定量RT-PCR

Abstract:

NaCl stimulation affects the activity of phosphofructokinase (PFK) and survival rate of freeze-dried Lactobacillus bulgaricus. In the late logarithmic phase, adding 2% (W/V) NaCl to the growth medium markedly increased the survival rate of freeze-dried L. bulgaricus. Meanwhile, the activity of PFK in L. bulgaricus after NaCl stimulation was determined by reversed phase high performance liquid chromatography (RP-HPLC). The results showed that PFK activity was increased significantly by NaCl stimulation. In addition, a semi-quantitative RT-PCR method was applied to detect the PFK gene expression in different condition. The results indicated that the PFK gene expression was increased before freeze-drying and almost unchanged after freeze-drying. NaCl stimulation could enhance the survival rate of freeze-dried cells, and PFK might affect the survival of Lactobacillus bulgaricus.

Key words:Lactobacillus bulgaricus, Freeze-drying, NaCl stimulation, Phosphofructokinase, Semi-quantitative RT-PCR