pH对产叶酸植物乳杆菌叶酸产量及相关基因表达的影响

叶酸是细胞代谢的重要中间体，人类由于缺乏叶酸生物合成途径中的关键酶，需要从膳食中摄取叶酸。由于谷氨酸尾数目的差别，生物合成的叶酸更容易被人体利用。一些植物乳杆菌菌株可以合成叶酸，但培养条件对叶酸合成有较大影响。选择一株高产叶酸的植物乳杆菌4_3菌株，探讨了在同一培养基中，不调节pH和使pH稳定在6.0对其生长状况和叶酸合成的影响。比起不调节pH，维持pH 6.0可以长期保持较高的活细胞密度。实时荧光定量PCR的结果显示，在pH 6.0的培养基中，叶酸合成相关基因表达量均要高于不调节pH的培养基。

Effect of pH value on folate production and gene expression of Lactobacillus plantarum

Folate is an important intermediate in cellular metabolism. However, because of lack of key enzymes in folate biosynthetic pathway, humans require folate from diet. Due to the difference in the number of glutamate, biosynthesis folate is superior to chemical synthetic folic acid by the body. Some Lactobacillus plantarum strains have the ability to synthetize folate. The extent of folate production and its form depend on the strain and culture conditions. The primary objective of this study is to gain a better understanding of the effects of pH on folate production and related gene expression in L. plantarum strain 4_3, which can generate high folate yields. Bacteria in pH 6.0 medium could still maintain a high cell density after logarithmic growth, but the folate content in the corresponding medium decreased. Real-time fluorescence quantitative PCR results showed that the expression of folate biosynthesis-related genes in pH 6.0 medium was higher as compared with those without regulated pH values.