ColV~+ strains of Escherichia coli produced larger inhibitory zones when these strains grown on nutrient agar containing phosphate after overlaid sensitive indicators. This appears that production of colicin V is increased by the addition of phosphate to nutrient agar. It was sure that stimulation of phosphate to colicin V formation results from its effect in reducing divalent cation levels in nutrient agar since adding EDTA to nutrient agar had the same effect as phosphate, but the addition of Mg~(2+) or Ca~(2+) had the oppsite effect. Therefore nutrient agar supplemented with phosphate can be used to isolate and identificate ColV~+ strains of E. coli.

Objective To observe the effect of the optimized formulas of extracts of Radix Astragali and Radix Angelicae Sinensis on the survival status of the idiopathic pulmonary fibrosis (IPF) mice,and on the expression levels of transforming growth factor-β (TGF-β) and vascular endothelial growth factor(VEGF),so as to optimize the therapeutic regimen and to explore the therapeutic mechanism.Methods One hundred and five SPF ICR male mice were randomly divided into normal group,model group and 5 Chinese medicine treatment groups (group 1,2,3,4,5 of the optimized formula of Radix Astragali and Radix Angelicae Sinensis extracts).The mice in the model group and the 5 treatment groups were intratracheally injected with bleomycin (5 mg/kg) to induce the pulmonary fibrosis model.On day 21,the lung tissues were taken out for the test.Hydroxyproline content was detected by alkaline hydrolysis method,and morphological changes of lung tissues were observed by hematoxylineosin (HE) staining and Mallory's staining methods.The expression levels of TGF-β and VEGF were detected by polymerase chain reaction (PCR).Results The HE staining and Mallory's staining results showed that the pulmonary fibrosis in the 5 treatment groups was relieved as compared with that in the model group,especially in the group 1,and the alveolar structure recovered better.The 21-day overall death rate in the treatment groups were lower than those in the model group,and group 1 and group 5 had the lowest rates,the difference being statistically significant (P＜ 0.05).Compared with the model group,the content of hydroxyproline in the lung tissues of the treatment groups were decreased to some degrees,and there was significant difference (P ＜ 0.05 or P ＜ 0.01).The expression levels of TGF-β and VEGF in model group were higher than those in normal group,but were deceased in the treatment groups to some degrees,except TGF-β expression in group 5,and the difference was significant(P ＜ 0.05 or P ＜ 0.01).Conclusion When the contents of Radix Astragali water-extract and Radix Angelicae Sinensis alcohol-extract were predominated,the extract formula exerts certain effects on decreasing hydroxyproline content in the lung tissues,inhibiting the expression levels of TGF-β and VEGF,and relieving the degree of pulmonary fibrosis in IPF mice.