Metabolic characteristics of methionine by in vitro fermentation with bacteria from different swine intestinal segment

Abstract:

[Objective] This study aims to study metabolic characteristics of methionine by caecal and colonic bacteria compared with ileal bacteria from pigs using in vitro fermentation. [Methods] We took ileal, caecal and colonic chyme from four Duroc×Landrace×Yorkshire hybridization pigs as inoculum, and fermented in vitro separately. Control group 1 was without adding the chyme and Control group 2 was without adding methionine. [Results] Methionine disappeared 21.9% in the cecum group, significantly higher than that in the ileum group (16.3%) and colon group (16.7%) (P<0.05). The cecum group had the highest amount of short chain fatty acids (P<0.05), with the highest decrease of pH value. Moreover, the cecum group had the highest concentration of microbial crude protein, compared with the other two groups (P<0.05). Nevertheless, gas production and ammonia nitrogen (NH₃N) concentration in the ileum group were significantly higher than those in the cecum and colon group (P<0.05). At the phylum level, total bacteria and Firmicutes population were similar among all groups (P>0.05), and the counts of Bacteroidetes was highest in the cecum group. At the genus level, Escherichia coli counts in the cecum and colon group were significant lower than that in the ileum group (P<0.05), whereas the counts of Clostridium leptum and Clostridium cluster XIVa in the cecum and colon group were both higher than those in the ileum group. Bifidobacterium counts were similar among all groups (P>0.05). [Conclusion] In vitro fermentation using methionine as a substrate, the utilization rate of methionine by caecal bacteria is higher than that by ileal bacteria from pigs, accomplished with altering other fermentation parameters and producing microbial protein. Compared with in vitro fermentation of ileal bacteria, the counts of Clostridium leptum and Clostridium cluster XIVa are higher, whereas the Escherichia coli counts is lower after fermentation of the large intestinal bacteria.