Selection of Immunobiotic Ligilactobacillus salivarius Strains from the Intestinal Tract of Wakame-Fed Pigs: Functional and Genomic Studies

Abstract

In this article, Ligilactobacillus salivarius FFIG strains, isolated from the intestinal tract of wakame-fed pigs, are characterized according to their potential probiotic properties. Strains were evaluated by studying their interaction with porcine intestinal epithelial (PIE) cells in terms of their ability to regulate toll-like receptor (TLR)-3- or TLR4-mediated innate immune responses, as well as by assessing their adhesion capabilities to porcine epithelial cells and mucins. These functional studies were complemented with comparative genomic evaluations using the complete genome sequences of porcine L. salivarius strains selected from subgroups that demonstrated different “immune” and “adhesion” phenotypes. We found that their immunomodulatory and adhesion capabilities are a strain-dependent characteristic. Our analysis indicated that the differential immunomodulatory and adhesive activities of FFIG strains would be dependent on the combination of several surface structures acting simultaneously, which include peptidoglycan, exopolysaccharides, lipoteichoic acid, and adhesins. Of note, our results indicate that there is no correlation between the immunomodulatory capacity of the strains with their adhesion ability to mucins and epithelial cells. Therefore, in the selection of strains destined to colonize the intestinal mucosa and modulate the immunity of the host, both properties must be adequately evaluated. Interestingly, we showed that L. salivarius FFIG58 functionally modulated the innate immune responses triggered by TLR3 and TLR4 activation in PIE cells and efficiently adhered to these cells. Moreover, the FFIG58 strain was capable of reducing rotavirus replication in PIE cells. Therefore, L. salivarius FFIG58 is a good candidate for further in vivo studying the protective effect of lactobacilli against intestinal infections in the porcine host. We also reported and analyzed, for the first time, the complete genome of several L. salivarius strains that were isolated from the intestine of pigs after the selective pressure of feeding the animals with wakame. Further genomic analysis could be of value to reveal the metabolic characteristics and potential of the FFIG strains in general and of the FFIG58 strain, in particular, relating to wakame by-products assimilation.

Functional and Genomic Characterization of Ligilactobacillus salivarius TUCO-L2 Isolated From Lama glama Milk: A Promising Immunobiotic Strain to Combat Infections

“…Additionally, the ability of L. salivarius TUCO-L2 to adhere to porcine intestinal epithelial (PIE) cells was assessed. Comparison of the TUCO-L2 strain with the FFIG58 and FFIG79 strains, which have been demonstrated to have high and low adhesion to PIE cells, respectively (Zhou et al, 2020 ) indicated that L. salivarius TUCO-L2 adheres to PIE cells, and the adhesion was significantly different from that of the two control strains ( Figure 4B ).…”

“…Porcine mucin from the small intestine was purified as described in Materials and Methods and used to evaluate the adhesion of the TUCO-L2 strain ( Figure 4A ). L. salivarius FFIG58 and FFIG79 isolated from the intestinal tract of wakame-fed pigs were used for comparison; these strains have been demonstrated to have low and high binding to porcine mucins, respectively (Zhou et al, 2020 ). L. salivarius TUCO-L2 demonstrated strong binding to porcine mucins that was not different from the binding of the FFIG79 strain ( Figure 4A ).…”

“…Letters indicate significant differences (P < 0.05), a < b < c. assessed. Comparison of the TUCO-L2 strain with the FFIG58 and FFIG79 strains, which have been demonstrated to have high and low adhesion to PIE cells, respectively (Zhou et al, 2020) indicated that L. salivarius TUCO-L2 adheres to PIE cells, and the adhesion was significantly different from that of the two control strains ( Figure 4B). The ability of L. salivarius TUCO-L2 to differentially modulate the innate immune response in PIE cells was evaluated by triggering the activation of TLR4 in lactobacilli-treated epithelial cells ( Figure 5).…”

Lactobacillus delbrueckii CRL 581 Differentially Modulates TLR3-Triggered Antiviral Innate Immune Response in Intestinal Epithelial Cells and Macrophages

“…The adhesion of L. delbrueckii subsp. lactis CRL 581 to PIE cells was performed using fluorescent bacteria and the microplate method, as described previously [25]. In these experiments, L. salivarius FFIG58 and L. salivarius FFIG79 strains [25] were used for comparisons.…”

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“…Porcine mucin from the small intestine was purified as described in Materials and Methods and used to evaluate the adhesion of the TUCO-L2 strain ( Figure 4A). L. salivarius FFIG58 and FFIG79 isolated from the intestinal tract of wakame-fed pigs were used for comparison; these strains have been demonstrated to have low and high binding to porcine mucins, respectively (Zhou et al, 2020). L. salivarius TUCO-L2 demonstrated strong binding to porcine mucins that was not different from the binding of the FFIG79 strain ( Figure 4A).…”