PSVIII-7 Effects of Bacillus subtilis on colon digesta metabolomic profiles in weanling pigs experimentally infected with a pathogenic E. coli

Our previous studies have shown that supplementation of Bacillus subtilis enhanced growth rate, improved gut barrier function, and modified colon microbiome of weaned pigs infected with pathogenic Escherichia coli (E. coli). The objective of this experiment was to investigate the effects of Bacillus subtilis on colon digesta metabolomic profiles of weaned pigs experimentally infected with F18 E. coli. Forty-eight pigs (6.73 ± 0.77 kg BW) were individually housed in disease containment rooms and randomly allotted to one of the four treatments (12 pigs/treatment). Four treatments included negative control (NC), positive control (PC), low-dose (1.28 × 109 CFU Bacillus subtilis/kg feed), and high-dose (2.56 × 109 CFU Bacillus subtilis/kg feed). The experiment lasted 18 d [7 d before and 11 d after first inoculation (d 0)]. The F18 E. coli inoculum was orally provided to all pigs with the dose of 1010 cfu/3 mL for 3 consecutive days, except NC. Twenty-four pigs (6 pigs/treatment) were euthanized on d 5 post-inoculation (PI) and the remained pigs were euthanized on d 11 PI to collect colon digesta for the analysis of metabolomic profiles by gas chromatography time of flight-mass spectrometer (GCTOF-MS). All processed data were statistically analyzed and evaluated by online MetaboAnalyst tool. No significant differences were observed in the metabolites between NC and PC on d 5 and 11 PI. Compared with PC, low- and high-dose Bacillus subtilis reduced (Fold change > 1.5; FDR < 0.20) four metabolites (proline, 2-hydroxyglutaric acid, lysine, and glutamic acid) and two metabolites (ribose, and D-xylulose) in colon digesta on d 5 PI, respectively. These metabolites were related to aminoacyl-tRNA-biosynthesis, arginine and proline metabolism, and lysine degradation. In conclusion, supplementation of Bacillus subtilis modified the levels of microbial metabolites associated with amino acid metabolism in colon digesta of pigs.