NaCl刺激对乳杆菌冻干存活率及胞内磷酸果糖激酶的影响

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2h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.%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 thePFK 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.