In vitro characterization and analysis of probiotic species in the chicken intestine by real-time polymerase chain reaction.

Two experiments, 1 in vitro and 1 in vivo study, were conducted to analyze probiotic species characteristics and survival in the intestine of broiler birds. The in vitro study characterized the effect of bile salt supplementation and pH on the proliferation of Lactobacillus reuteri, Pediococcus acidilactici, Bifidobacterium animalis, and Enterococcus faecium. L. reuteri and P. acidilactici growth was maximal when the media was supplemented with 1.0% bile salt, whereas B. animalis and E. faecium growth was maximal when the media was supplemented with 0.5% bile salt. Altering the pH between 2.5 and 5.8 did not significantly (P > 0.05) alter the proliferation of L. reuteri and B. animalis. Decreasing the pH from 5.8 to 2.0 decreased P. acidilactici growth, whereas it increased the E. faecium proliferation. The in vivo study quantified the concentration of L. reuteri, P. acidilactici, B. animalis, E. faecium, and L. salivarius in different intestinal sections from birds supplemented with and without synbiotic containing the above 5 bacteria species. Birds were supplemented with and without synbiotic for 18 d, after which all birds were fed the same basal diet with no synbiotic. At 72 h of feeding, the basal diet with no synbiotics, when the probiotic species in the feed is expected not to confound the recovery of probiotic species from the intestine, intestinal contents were collected. L. reuteri, P. acidilactici, E. faecium, and L. salivarius were below detectable amount in the control group. L. reuteri concentration expressed as copy numbers/g and as percentage of total bacteria was highest in the jejunum and ileum, respectively. E. faecium concentration was highest in the ileum. The copy number of P. acidilactici increased at the duodenum and plateaued after duodenum. L. salivarius concentration was highest in the jejunum. It can be concluded that real-time PCR can be applied to quantify the concentrations of probiotic species in the intestine and probiotic species differ in their ability to colonize different sections of the intestine.