Data_Sheet_1_Ethnic Specificity of Species and Strain Composition of Lactobacillus Populations From Mother–Infant Pairs, Uncovered by Multilocus Sequence Typing.pdf

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.

学界普遍认为，在哺乳期，婴儿肠道内的潜在益生菌菌株主要源自母体肠道。目前尚不明确，兼性共生乳杆菌是否严格遵循母-婴垂直传播路径，且在母-婴队列中呈现出基于物种和菌株组成的族群特异性。本研究从两个互不通婚的族群的31对健康母-婴对中，共分离得到16个曾归属于乳杆菌属（Lactobacillus）的物种（总计365株）以及11个相关物种（总计280株）的菌株。研究结果显示，两个族群间的乳杆菌属物种组成与菌株丰度均存在显著差异。在分离得到的106株副干酪乳杆菌（Lacticaseibacillus paracasei）中，研究人员通过多位点序列分型（multilocus sequence typing, MLST）技术将其中64株代表菌株划分为27个序列型（sequence types, ST），其中20个序列型源自33株维吾尔族菌株，7个序列型源自31株黎族菌株，且不同族群的菌株之间未检测到基因同源重组事件。通过go-EBURST聚类分析发现，除少数母-婴对中检测到多个序列型外，大多数来自同一母-婴对的副干酪乳杆菌分离株均为单系群，从而证实了乳杆菌在菌株水平上的垂直传播现象。更值得关注的是，来自同一族群的副干酪乳杆菌分离株相较于其他族群的菌株，更易被归入具有相似聚糖代谢谱的特定进化支或克隆复合体（clonal complex, CC），这在很大程度上支持了族群特异性假说。本研究从母婴健康的视角出发，为针对高度同质化的本地人群开发定制化益生菌制剂提供了实验依据。