Correlation analysis between the gut microbiota and metabolome
To obtain insight into microbiota-metabolic axis, we conducted a correlation analysis on the significant microbial taxa and metabolites. Gut microbiota analysis showed that infection of APEC increased the abundance of Clostridiales_vadinBB60_group , andRuminococcaceae_UCG_014 (Fig. 6A). Correlation analysis showed that they were both positively associated with Xanthine, Deoxyinosine, 21-Hydroxypregnenolone, Serotonin, 3,4-Dihydroxyhydrocinnamic acid, 8,9-DiHETrE, Dihydrofolic acid, Corticosterone, and Dihydrocortisol, while were negatively associated with (S)-2-Amino-6-Oxohexanoate and Guanine (Fig. 10A). In contrast, pretreatment with BAI reduced the concentration of 21-Hydroxypregnenolone, Serotonin, 8,9-DiHETrE, Dihydrofolic acid, and Dihydrocortisol induced by APEC (Table S11). Except for reduced the abundance ofClostridiales_vadinBB60_group andRuminococcaceae_UCG_014 induced by APEC in the gut, pretreated with BAI also increased the abundance of Blautia , andFournierella (Fig. 6B). Correlation analysis showed that they were both positively associated with 2-oxoarginine, while negatively associated with L-Asparagine, 3-Dehydroquinate, Prostaglandin G2, 5-Phosphoribosylamine, 5-Methoxyindoleacetate, and 4-Pyridoxic acid (Fig. 10B). In addition, gut microbiota analysis showed thatIntestinimonas was enriched in the gut of chicken that treated with BAI compared to the CON group (Fig. 6C). As shown in Fig. 10C,Intestinimonas was positively associated with the abundance of Gentamicin C1a, 3,4-Dihydroxyhydrocinnamic acid, Selenodiglutathione, L-Arabinose, Serotonin, Norfloxacin, 2-Oxoarginine, Epinephrine, and Xanthine, while both negatively associated with Gulonic acid, 5-Methoxyindoleacetate, Prostaglandin G2, 3,4-Dihydroxyhydrocinnamic acid, Palmitic acid, Dehydroepiandrosterone, Isonicotinic acid, FMN, 2-Dehydro-3-Deoxy-L-Rhamnonate, 4-Pyridoxic acid, 12(S)-HpETE, Ubiquinone-1, D-Fructose, Picolinic acid, (S)-2-Amino-6-Oxohexanoate, 5-Phosphoribosylamine, Hydroquinone. These results suggested the protective effect of baicalin on colibacillosis induced by APEC was not only associated with regulating gut metabolites induced by APEC, but may also associated the production of new gut metabolites after baicalin metabolized by APEC.