连翘水煎液发酵工艺优化及非靶向代谢组学分析OA

This study aimed to investigate the fermentation conditions of Forsythia suspensa aqueous extract using three probiotic strains and to analyze the changes in components before and after fermentation.Different concentrations of Forsythia suspensa aqueous extract were fermented with probiotics to screen for the optimal bacterial strain and suitable extract concentration.Using the viable count of probiotics in the fermentation product and the minimum inhibitory concentration(MIC)against Klebsiella pneumoniae(KP)as evaluation indicators,the optimal fermentation duration,temperature,and inoculation size for the selected strain were determined.Non-targeted metabolomics analysis was performed on the supernatant with the best fermentation effect.The results showed that the optimal fermentation strain was Enterococcus faecalis(EF),and the suitable concentration of Forsythia suspensa aqueous extract was 125.0 g/L.The optimal fermentation conditions were as follows:Fermentation time of 36 hours,temperature of 25℃,and inoculation size of 5%.Under these conditions,the viable bacterial count in the fermentation product was high,and the MIC against KP was 31.3 g/L,reduced to 1/16 of that before fermentation.Compared with before fermentation,a total of 136 substances were up-regulated(including phillyrin,succinic acid,coumaric acid,etc.)and 379 substances were down-regulated(including sucrose,etc.)after fermentation.Pathway enrichment analysis indicated that pathways such as the tricarboxylic acid cycle and glyoxylate and dicarboxylate metabolism were up-regulated,while pathways including glycolysis and phenylpropanoid biosynthesis were down-regulated.This promoted the increase in content of antibacterial active substances like phillyrin and succinic acid.The study shows that the optimized fermentation process can significantly enhance the antibacterial activity of Forsythia suspensa aqueous extract,providing a reference for related research and the development of novel green feed additives or functional feed ingredients.