Effects Of Fluoride On The Growth Characteristics Of The Predominant Intestinal Bacteria In Mice

Objective:To study the effect of NaF on growth, glycolytic metabolic enzymes and the expression of proteins of E. coli, Lactobacillus and Bifidobacterium.Method:The strains of E.coli, Lactobacillus and Bifidobacterium, which isolated from the mice intestine as experimental strains, were cultured in liquid culture with NaF, the concentration reached 0.1mmol/L, 1mmol/L, 10mmol/L, 100mmol/L respectively. The growth of E.coli, Lactobacillus and Bifidobacterium assayed by turbidimetry. The bacterial acid production were detected by the pH meter. The total protein of E. coli, Lactobacillus and Bifidobacterium were extracted, then the changes in the expression of proteins were analyzed by SDS-PAGE.Results:1. After cultured 24h. low doses of NaF(0.1mmol/L, 1mmol/L) had a positive effect on the growth of E. coli, and inhibited the acid production, increased the gas production. High doses of NaF(100mmol/L) had an obvious inhibitory effect on the growth of E. coli, inhibited the acid production and reduced the gas production at the same time. After cultured 48h, low doses of NaF(0.1 mmol/L) had no significant effect on the growth and acid production of Lactobacillus, while it promoted the growth and acid production of Bifidobacterium; high doses of NaF(100mmol/L) had an inhibitory effect on the growth and the acid production of Lactobacillus and Bifidobacterium.2. When the doses of NaF reached 10mmol/L, the activity of hexokinase. pyruvate kinase, succinate dehydrogenase and citrate synthase of E. coli were inhibited. When the doses of NaF reached lmmol/L, the activity of hexokinase, pyruvate kinase and lactate dehydrogenase of Lactobacillus and Bifidobacterium were inhibited.3. After the E. coli were cultured in liquid culture with 10mmol/L NaF for 18h, the protein concentration of E. coli was 0.33mg/mL, and the protein of 150kDa and 35kDa were up-regulated. After the Lactobacillus were cultured in liquid culture with 1mmol/L NaF for 36h, the protein concentration of Lactobacillus was 1.78mg/mL, and the protein of 250kDa, 132kDa and 75kDa were up-regulated, while the protein of 92kDa,47kDa and 31kDa were down-regulated; After the Bifidobacterium were cultured in liquid culture with lmmol/L NaF for 36h, the protein concentration of Bifidobacterium was 1.69mg/mL, the protein of 28kDa and 75kDa were up-regulated, while the protein of 31kDa,47kDa and 62kDa were down-regulated.Conclusion:The growth and the gas production of E. coli were promoted by low doses of NaF, while the acid production were inhibited; the growth of were promoted at the same time. The growth and the acid production of E. coli, Lactobacillus and Bifidobacterium were inhibited by high doses of NaF, the gas production of E. coli were also inhibited by high doses of NaF. The activity of metabolic enzymes of E. coli, Lactobacillus and Bifidobacterium were inhibited respectively after treated with 10mmol/L(E. coli) and 10mmol/L(Lactobacillus and Bifidobacterium) NaF, and the expressions of the bacterial protein were also affected by NaF.