Abstract
The maternal gut is thought to be the principal source of potential probiotic bacteria in the infant gut during the lactation stage. It is not clear whether facultative symbiont lactobacilli strictly follow vertical transmission from mother to infant and display the ethnic specificity in terms of species and strain composition in mother–infant cohorts. In the present study, a total of 16 former Lactobacillus species (365 strains) and 11 species (280 strains) were retrieved from 31 healthy mother–infant pairs of two ethnic groups, which have never intermarried, respectively. The result showed that the composition and number of Lactobacillus species between the two ethnic groups varied. Among 106 Lacticaseibacillus paracasei strains isolated, 64 representative strains were classified into 27 sequence types (ST) by means of multilocus sequence typing (MLST), of which 20 STs derived from 33 Uighur strains and 7 STs from 31 Li strains, and no homologous recombination event of genes was detected between strains of different ethnic groups. A go-EBURST analysis revealed that except for a few mother–infant pairs in which more than one STs were detected, L. paracasei isolates from the same mother–infant pair were found to be monophyletic in most cases, confirming vertical transfer of Lactobacillus at the strain level. More notably, L. paracasei isolates from the same ethnic group were more likely than strains from another to be incorporated into a specific phylogenetic clade or clonal complex (CC) with similar metabolic profile of glycan, supporting the hypothesis of ethnic specificity to a large degree. Our study provides evidence for the development of personalized probiotic tailored to very homogenous localized populations from the perspective of maternal and child health.
Highlights
The human gut represents a complex ecosystem that is colonized by trillions of microorganisms which influence the physiology, immune function, and health status of the host (Martin et al, 2016)
Our results coincided with the observation of Tannock (2002) and Kirtzalidou et al (2011), who reported that the common Lactobacillus species isolated from breast milk and infant gut included L. gasseri, L. paracasei, L. salivarius, and L. fermentum, supporting the hypothesis that these lactobacilli species are likely to be persistent colonizers in the human gut (Tannock, 2002; Kirtzalidou et al, 2011)
The results of multilocus sequence typing (MLST) revealed that except for a few mother–infant pairs with more than one detected sequence types (ST), most L. paracasei strains from the same mother– infant pair were monophyletic, clearly confirming vertical transmission of strains between infant and mother gut
Summary
The human gut represents a complex ecosystem that is colonized by trillions of microorganisms which influence the physiology, immune function, and health status of the host (Martin et al, 2016). Ethnic Specificity of Lactobacillus Strains for the transfer of potential probiotics from mother to infant, especially the members of the former genera Lactobacillus and Bifidobacterium (McGuire and McGuire, 2017; Sindi et al, 2021). Like Bifidobacterium, Lactobacillus was recognized as one of the key contributors to beneficial effects for maternal– infant health by providing an inoculum of Lactobacillus to the infant gut. Some members of the former genus Lactobacillus play an important role in regulating human metabolism and immune system (Abbasi et al, 2021). Lactobacillus are considered as the key elements of the defensive system in the infant’s intestines (Solís et al, 2010), which inhibits a wide spectrum of infant pathogenic bacteria by competitive exclusion or production of antibacterial compounds (Olivares et al, 2006). Lactobacillus GG and lactoferrin could enhance the antibacterial defense of the neonatal intestinal epithelium (Sherman et al, 2004)
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