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

Sandra Quilodrán-Vega,Mikado Tomokiyo,Binghui Zhou,Yoshihito Suda,Julio Villena,Haruki Kitazawa,Lorena Arce,Md Aminul Islam,Leonardo Albarracin,Flavia Mansilla,Imad Al Kassaa

doi:10.3389/fmicb.2020.608752

Abstract

Potential probiotic or immunobiotic effects of lactic acid bacteria (LAB) isolated from the milk of the South American camelid llama (Lama glama) have not been reported in published studies. The aim of the present work was to isolate beneficial LAB from llama milk that can be used as potential probiotics active against bacterial pathogens. LAB strains were isolated from llama milk samples. In vitro functional characterization of the strains was performed by evaluating the resistance against gastrointestinal conditions and inhibition of the pathogen growth. Additionally, the adhesive and immunomodulatory properties of the strains were assessed. The functional studies were complemented with a comparative genomic evaluation and in vivo studies in mice. Ligilactobacillus salivarius TUCO-L2 showed enhanced probiotic/immunobiotic potential compared to that of other tested strains. The TUCO-L2 strain was resistant to pH and high bile salt concentrations and demonstrated antimicrobial activity against Gram-negative intestinal pathogens and adhesion to mucins and epithelial cells. L. salivarius TUCO-L2 modulated the innate immune response triggered by Toll-like receptor (TLR)-4 activation in intestinal epithelial cells. This effect involved differential regulation of the expression of inflammatory cytokines and chemokines mediated by the modulation of the negative regulators of the TLR signaling pathway. Moreover, the TUCO-L2 strain enhanced the resistance of mice to Salmonella infection. This is the first report on the isolation and characterization of a potential probiotic/immunobiotic strain from llama milk. The in vitro, in vivo, and in silico investigation performed in this study reveals several research directions that are needed to characterize the TUCO-L2 strain in detail to position this strain as a probiotic or immunobiotic that can be used against infections in humans or animals, including llama.

Highlights

The Camelidae family comprises the dromedary camel or camel of the plains (Camelus dromedarius), Bactrian camel or camel of the mountains (Camelus bactrianus), and four species of South American camelids, including guanaco (Lama guanicoe), vicuña (Vicugna vicugna), alpaca (Lama pacos), and llama (Lama glama) (Fukuda, 2013; Zarrin et al, 2020)
The TUCO-L1 and TUCO-L2 strains were resistant to all tested concentrations of NaCl; the growth of the TUCO-L3 and TUCO-L5 strains was inhibited by concentrations of NaCl over 6% (w/v) (Supplementary Table 1)
One of the isolated strains, L. salivarius TUCO-L2, demonstrated several characteristics that would allow the use of this strain as a probiotic against intestinal infections

Summary

Introduction

The Camelidae family comprises the dromedary camel or camel of the plains (Camelus dromedarius), Bactrian camel or camel of the mountains (Camelus bactrianus), and four species of South American camelids, including guanaco (Lama guanicoe), vicuña (Vicugna vicugna), alpaca (Lama pacos), and llama (Lama glama) (Fukuda, 2013; Zarrin et al, 2020). In the past decade, considerable efforts were aimed at characterizing the microbial populations of the camel milk to isolate the beneficial strains. Subsequent studies confirmed the dominance of enterococci and lactococci in the cultivable bacteria from camel milk but detected certain differences in the predominant species of lactobacilli (Elbanna et al, 2018; Rahmeh et al, 2019; Zhao et al, 2020) that included Lacticaseibacillus paracasei (basonym: Lactobacillus paracasei), Lacticaseibacillus rhamnosus (basonym: Lactobacillus rhamnosus), and Limosilactobacillus reuteri (basonym: Lactobacillus reuteri). In addition to the characterization of microbial populations, certain strains with beneficial effects have been isolated from the camel milk. The E. faecium LCW44 strain isolated from raw camel milk demonstrated a pronounced inhibitory effect against Listeria spp. and S. aureus (Vimont et al, 2017).

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