Predominance of a bacteriocin-producing Lactobacillus salivarius component of a five-strain probiotic in the porcine ileum and effects on host immune phenotype

Abstract

Relative predominance of each of five probiotic strains was investigated in the ileum of weaned pigs, compared with that in feces, when administered in combination at c. 5 x 10(9) CFU day(-1) for 28 days. Probiotic was excreted at 10(6)-10(9) CFU g(-1) feces, while ileal survival ranged from 10(2) to 10(6) CFU g(-1) digesta. In contrast to the feces, where Lactobacillus murinus DPC6002 predominated, the bacteriocin-producing Lactobacillus salivarus DPC6005 dominated over coadministered strains both in the ileum digesta and in mucosa. Probiotic administration did not alter counts of culturable fecal Lactobacillus or Enterobacteriaceae but higher ileal Enterobacteriaceae were observed in the ileal digesta of probiotic-fed pigs (P<0.05). We observed decreased CD25 induction on T cells and monocytes (P<0.01) and decreased CTLA-4 induction (P<0.05) by the mitogen phytohemagglutinin on CD4 T cells from the probiotic group. Probiotic treatment also increased the proportion of CD4+ CD8+ T cells within the peripheral T-cell population and increased ileal IL-8 mRNA expression (P<0.05). In conclusion, superior ileal survival of L. salivarius compared with the other coadministered probiotics may be due to a competitive advantage conferred by its bacteriocin. The findings also suggest that the five-strain combination may function as a probiotic, at least in part, via immunomodulation.

Modulation of the gut microbiota by prebiotic fibres and bacteriocins

“…For instance, a Lactobacillus salivarius strain producing salivaricin P becomes predominant in porcine ileum when administered in combination with other probiotic strains that do not produce bacteriocins [82]. Antagonistic activity of the bacteriocin producers against a number of pathogenic or antibiotic-resistant bacterial strains in the gut has been a major focus of gut microbiota studies.…”

Beneficial modulation of the gut microbiota

“…Increased Bacteroidetes and Proteobacteria, decreased Actinobacteria [120] Temporarily reduced weight gain in pigs [117] Vancomycin Decreased Firmicutes and Bacteroidetes, increased Proteobacteria [121] Decrease in weight gain, fasting blood glucose, plasma TNFa and triglyceride levels in DIO mice [121] Sub-therapeutic antibiotic therapy * Increased Firmicutes, especially Lachnospiraceae, relative to Bacteroidetes [108] Increased adiposity and bone mineral density in mice [108] 5 strain probiotic mixture ** Reduced shedding of Samonella enterica serovar Typhimurium in pigs [119] Reduced incidence, severity and duration of diarrhoea in pigs. Also, increased weight gain [119] Lactobacillus gasseri SBT2055, producer of gassericin T bacteriocin Not reported Decreased abdominal adiposity, body weight, BMI, waist circumference and hip circumference in human adults [131].…”

“…It was subsequently established that the only bacteriocin-producing strain, L. salivarius DPC6005, was the dominant member of the cocktail in both the ileum digesta and in the mucosa. It could not be established, however, if bacteriocin production was directly responsible for anti-Salmonella activity [120].…”

Probiotics – do they have a role in the pig industry?

“…Other than the described mechanisms, probiotics may provide defence to the cells through induction of anti-inflammatory cytokines, and reduction of pro-inflammatory cytokines, from enterocytes and intestinal immune cells recruited to sites of inflammation by probiotics (O'Hara et al, 2006;Walsh et al, 2008;Wang et al, 2009). Cytokines are also involved in the maintainance of barrier integrity induced by probiotics (Roselli et al, 2007).…”