The Host Genotype and Environment Affect Strain Types of Bifidobacterium longum subsp. longum Inhabiting the Intestinal Tracts of Twins

Abstract

bTo investigate the influences of host genotype and environment on Bifidobacterium longum subsp. longum inhabiting human intestines at the strain level, six pairs of twins, divided into two groups (children and adults), were recruited. Each group consisted of two monozygotic (MZ) twin pairs and one dizygotic (DZ) twin pair. Child twins had been living together from birth, while adult twins had been living separately for 5 to 10 years. A total of 345 B. longum subsp. longum isolates obtained from 60 fecal samples from these twins were analyzed by multilocus sequence typing (MLST), and 35 sequence types (STs) were finally acquired. Comparison of strains within and between the twin pairs showed that no strains with identical STs were observed between unrelated individuals or within adult DZ twin pairs. Eight STs were found to be monophyletic, existing within MZ twins and child DZ twins. The similarity of strain types within child cotwins was significantly higher than that within adult cotwins, which indicated that environment was one of the important determinants in B. longum subsp. longum strain types inhabiting human intestines. However, although these differences between MZ and DZ twins were observed, it is still difficult to reach an exact conclusion about the impact of host genotype. This is mainly because of the limited number of subjects tested in the present study and the lack of strain types tracing in the same twin pairs from birth until adulthood.T he human intestine is a complex microbial ecosystem. Recent research has shown that gut microbes control or influence many metabolic pathways in the human host (1, 2, 3). Bifidobacteria, which are naturally present in the colonic microbiota, represent up to 25% of the cultivable fecal bacteria in adults and 80% in infants (4). The interest in bifidobacteria has grown significantly, mainly because their presence has been associated with a healthy microbiota, which has led to their widespread use as functional ingredients in food and pharmaceutical products (4,5,6). Considering the rapidly increasing number of commercial and technological strains, it has been reported that probiotic characteristics such as antioxidant potential are strongly strain dependent (7). The FAO/WHO Guidelines for the Evaluation of Probiotics in Food reports the following: "The current state of evidence suggests that probiotic effects are strain specific" (8). Therefore, the health effects of probiotics as well as successful colonization and studies of their mechanism of action should be linked to a specific strain rather than be at species level. However, it is not clear what kinds of Bifidobacterium strains colonize a person, and little is known about the factors that exert an influence on the various strains.The drivers of intestinal bacteria are multiple and can be categorized as environment associated and host associated. Environment-associated factors include diet, geographical location, and the maternal source in early life (9,10,11,12). A recent study implies that the first bacte...

Association and Occurrence of Bifidobacterial Phylotypes Between Breast Milk and Fecal Microbiomes in Mother–Infant Dyads During the First 2 Years of Life

“…longum, which can be detected in the intestinal tracts of both adults and infants, the B. longum subsp. infantis, as a typical infant-type bifidobacterial phylotype is difficult to capture because it is a very low abundance taxon in the adult gut, even using metagenomic methods (Ward et al, 2013;Zhang et al, 2015;Vatanen et al, 2019). For example, only 10% of Finnish infants harbored Bifidobacterium longum subsp.…”

Evaluation of Bacterial Diversity and Evolutionary Dynamics of Gut Bifidobacterium longum Isolates Obtained from Older Individuals in Hubei Province, China

“…The dN / dS ratio for each locus varied between 0.01692 and 0.1405, and that for the concatenated sequences was 0.02392, indicating that these genes had undergone negative selection. Previously, Delétoile showed that the rpoB gene shows the highest dN / dS , and that purF has the most polymorphic sites ( 21 , 22 ). These findings were consistent with our results.…”

“…Genotyping—including AFLP ( 17 , 18 ), random amplified polymorphic DNA ( 15 , 19 ), pulsed-field gel electrophoresis ( 15 ), multilocus variable number of tandem repeat analysis ( 20 ), and MLST analyses ( 13 , 17 , 18 , 21 , 22 )—has been used to examine B. longum isolates. Of these, MLST was first used in 1998 for the evaluation of Neisseria meningitidis ( 23 ) and then started being used widely to evaluate epidemiological characteristics and for the typing analysis of bifidobacteria and lactobacilli.…”

“…Of these, MLST was first used in 1998 for the evaluation of Neisseria meningitidis ( 23 ) and then started being used widely to evaluate epidemiological characteristics and for the typing analysis of bifidobacteria and lactobacilli. MLST can be used to accurately discriminate different isolates within a species and subspecies by comparing allelic profiles, providing precise information on strain evolution, and performing population analysis and classification ( 17 , 18 , 21 , 22 , 24 ). It has a high resolution and can provide unambiguous genotype nomenclature and information that can be easily shared between laboratories ( 25 ).…”

“…It has a high resolution and can provide unambiguous genotype nomenclature and information that can be easily shared between laboratories ( 25 ). Previous studies have shown that MLST can be used for the subspeciation ( 13 ) and species delineation ( 22 ) of B. longum and to track the transmission of intestinal B. longum ( 18 , 21 ).…”