Exopolysaccharides Synthesized by Lactobacillus reuteri Protect against Enterotoxigenic Escherichia coli in Piglets

Abstract

bEnterotoxigenic Escherichia coli (ETEC) is a major cause of diarrhea in piglets; ETEC cells colonize the intestinal mucosa with adhesins and deliver toxins that cause fluid loss. This study determined the antiadhesive properties of bacterial exopolysaccharides (reuteran and levan) and related glycans (dextran and inulin) in a small intestinal segment perfusion (SISP) model. The SISP model used 10 jejunal segments from 5-week-old piglets. Five segments were infected with ETEC expressing K88 fimbriae (ETEC K88), while five segments were treated with saline. Every two segments (ETEC and non-ETEC infected) were infused with 65 ml of 10 g liter ؊1 of glycans or saline (control) for 8 h. High-resolution melting-curve (HRM) quantitative PCR (qPCR) indicated that E. coli is the dominant bacterium in infected segments, while other bacteria were predominant in noninfected segments. Infection by ETEC K88 was also verified by qPCR; gene copy numbers of K88 fimbriae and the heat-labile toxin (LT) in mucosal scrapings and outflow fluid of infected segments were significantly higher than those in noninfected segments. Genes coding for K88 fimbriae and LT were also detected in noninfected segments. LT amplicons from infected and noninfected segments were 99% identical over 481 bp, demonstrating the presence of autochthonous ETEC K88. All glycans reduced fluid loss caused by ETEC K88 infection. Reuteran tended (P ‫؍‬ 0.06) to decrease ETEC K88 levels in mucosal scraping sample, as judged by qPCR. Fluorescent in situ hybridization analysis demonstrated that reuteran significantly (P ‫؍‬ 0.012) decreased levels of adherent ETEC K88. Overall, reuteran may prevent piglet diarrhea by reducing adhesion of ETEC K88.

Feed Fermentation with Reuteran- and Levan-Producing Lactobacillus reuteri Reduces Colonization of Weanling Pigs by Enterotoxigenic Escherichia coli

“…Specifically, the reuteran produced by L. reuteri TMW1.656 reduces the adhesion of ETEC K88. In the present study, the reuteran-positive groups had lower copy numbers of genes for E. coli and the ETEC virulence factors than groups fed diets containing L. reuteri but not reuteran or levan, which may reflect the antiadhesive properties of reuteran in vitro (16) and in an in vivo model (17). Together with the findings presented in those prior reports, this study suggests that reuteran reduces the level of ETEC adhesion to the intestinal mucosa in vivo.…”

“…ETEC adhesion in vitro was also reduced by reuteran and levan, exopolysaccharides produced by Lactobacillus reuteri (16). The protective effect of reuteran was confirmed in vivo in the small intestinal segment loop perfusion model (17). Evidence for the effectiveness of probiotic cultures or antiadhesive glycans for the prevention of ETEC infection in vivo, however, remains limited.…”

“…The growth of specific strains of L. reuteri in cereal substrates also supports the formation of reutericyclin, an antibiotic with specific activity against Gram-positive pathogens (25,26). Moreover, the exopolysaccharides reuteran and levan, which prevent adhesion of ETEC K88 fimbriae to the porcine intestinal mucosa (16,17), are produced during the growth of L. reuteri in cereals (27,28). However, the specific contribution of exopolysaccharide formation to the inhibition of intestinal patho-gens by L. reuteri remains unknown.…”

Structure-function relationships of bacterial and enzymatically produced reuterans and dextran in sourdough bread baking application

“…To purify glucans produced by L. reuteri TMW1.656, the strain was cultured in sucrose mMRS broth for 16 h and subcultured overnight in 1 L sucrose-mMRS broth. Reuteran was harvested via 2 volume ethanol precipitation and purified by dialysis as described (Chen et al, 2014). The retentate was freeze dried and stored at −20°C.…”

Comparison of probiotic lactobacilli and bifidobacteria effects, immune responses and rotavirus vaccines and infection in different host species

“…One study evaluated the effects of bifidobacteria and LAPB (in place of AGPs) in newborn calves and piglets and demonstrated that these probiotics reduced mortality, improved weight gain, fecal condition and feed efficiency in both species (Abe et al, 1995). However, the effects of lactobacilli (including various strains of L. reuteri , as well as L. gasseri , L. acidophilus and L. fermentum ) supplementation on infectious diarrhea occurrence, growth performance and feed conversion in neonatal and weanling piglets varied with age, feeding status (sow milk versus milk replacer) and lactobacilli strain (Chang et al, 2001; Chen et al, 2014; Huang, 2004; Liu et al, 2014; Wang et al, 2009a; Wang et al, 2013; Wang, 2011; Wang et al, 2012; Yu, 2008) (Table 3). Potential mechanisms of lactobacilli beneficial effects proposed in these studies included alleviation of oxidative stress (Wang et al, 2013; Wang et al, 2009b), protective modulation of gut microbiota (Chang et al, 2001; Huang, 2004; Liu et al, 2014) and associated metabolic profiles (Liu et al, 2014), enhancement of T-cell differentiation, ileal cytokine production (Wang et al, 2009a) and serum IgG Ab levels (Yu, 2008).…”