NaCl刺激保加利亚乳杆菌对丙酮酸代谢及相关酶活性的影响

Effects of NaCl stimulation on pyruvate metabolism and enzyme activity in Lactobacillus bulgaricus

分析NaCl刺激保加利亚乳杆菌与冻干存活率的关系。高效液相色谱法分析葡萄糖、有机酸、乙酰辅酶A(Acetyl-CoA)以及胞内能量代谢变化;顶空气相色谱法测定乙醛含量;分光光度法和比色法测定关键酶活性。结果显示:NaCl刺激保加利亚乳杆菌对丙酮酸的代谢有显著影响,葡萄糖代谢速率提高48.18%(P<0.01),乳酸生成速率提高8.93%(P<0.01),关键中间代谢产物Acetyl-CoA的含量增加约31.35%(P<0.01);而乙酸含量出现负增长,乙醛生成速率降低22.86%(P<0.05)。胞内ATP代谢变化明显促进糖代谢速率;乳酸脱氢酶、乙酸激酶、磷酸乙酰转移酶的活性均有增加,而乙醛脱氢酶活性减弱。结果表明,NaCl刺激保加利亚乳杆菌对自身糖代谢的加快,丙酮酸代谢碳流向的重新分配以及关键酶活性的改变,可能与提高保加利亚乳杆菌的冻干存活率相关。

The relationship between NaCl stimulation on Lactobacillus bulgaricus and the survival rate of freeze-dried cells was analyzed.Glucose,organic acids,acetyl coenzyme A(Acetyl-CoA)and intracellular energy metabolism changes were mearsured by high performance liquid chromatography(HPLC).The content of acetaldehyde was determined by headspace gas chromatography(HS-GC).The activitity of key enzyme was mearsured by spectrophotometry and colorimetry.The results show that pyruvate metabolism on Lactobacillusbulgaricusis significantly changed by NaCl stimulation.The glucose metabolism rate and lactate production rate are increased by 48.18%(P<0.01)and 8.93%(P<0.01),respectively and the key mesostate Acetyl-CoA is increased by 31.35%(P<0.01)approximately.Acetic acid content show negative growth,and acetaldehyde formation rate is decreased by 22.86%(P<0.05).Intracellular ATP metabolism change accelerates the utilization of glucose.Lactate dehydrogenase,acetate kinase,and phosphate acetyltransferase activities are improved by NaCl stimulation,while aldehyde dehydrogenase activity is decreased.The results indicate that the increase survival rate of freeze-dried cells may be related to glucose utilization acceleration,pyruvate metabolism reroute,and key enzyme activity changes of Lactobacillus bulgaricu by NaCl stimulation.