Assessment of Bifidobacterium Species Using groEL Gene on the Basis of Illumina MiSeq High-Throughput Sequencing

The gut core microbial species Bifidobacterium longum: Colonization, mechanisms, and health benefits

Bifidobacterium longum (B. longum) is a species of the core microbiome in the human gut, whose abundance is closely associated with host age and health status. B. longum has been shown to modulate host gut microecology and have the potential to alleviate various diseases. Comprehensive understanding on the colonization mechanism of B. longum and mechanism of the host-B. longum interactions, can provide us possibility to prevent and treat human diseases through B. longum-directed strategies. In this review, we summarized the gut colonization characteristics of B. longum, discussed the diet factors that have ability/potential to enrich indigenous and/or ingested B. longum strains, and reviewed the intervention mechanisms of B. longum in multiple diseases. The key findings are as follows: First, B. longum has specialized colonization mechanisms, like a wide carbohydrate utilization spectrum that allows it to adapt to the host's diet, species-level conserved genes encoding bile salt hydrolase (BSHs), and appropriate bacterial surface structures. Second, dietary intervention (e.g., anthocyanins) could effectively improve the gut colonization of B. longum, demonstrating the feasibility of diet-tuned strain colonization. Finally, we analyzed the skewed abundance of B. longum in different types of diseases and summarized the main mechanisms by which B. longum alleviates digestive (repairing the intestinal mucosal barrier by stimulating Paneth cell activity), immune (up-regulating the regulatory T cell (Treg) populations and maintaining the balance of Th1/Th2), and neurological diseases (regulating the kynurenine pathway and quinolinic acid levels in the brain through the gut-brain axis).

Genetic specialization of key bifidobacterial phylotypes in multiple mother-infant dyad cohorts from geographically isolated populations

Little has been known about symbiotic relationships and host specificity for symbionts in the human gut microbiome so far. Bifidobacteria are a paragon of the symbiotic bacteria biota in the human gut. In this study, we characterized the population genetic structure of three bifidobacteria species from 58 healthy mother-infant pairs of three ethnic groups in China, geographically isolated, by Rep-PCR, multi-locus sequence analysis (MLSA), and in vitro carbohydrate utilization. One hundred strains tested were incorporated into 50 sequence types (STs), of which 29 STs, 17 STs, and 4 STs belong to B. longum subsp. longum, B. breve, and B. animalis subsp. lactis, respectively. The conspecific strains from the same mother-child pair were genetically very similar, supporting the vertical transmission of Bifidobacterium phylotypes from mother to offspring. In particular, results based on allele profiles and phylogeny showed that B. longum subsp. longum and B. breve exhibited considerable intraspecies genetic heterogeneity across three ethnic groups, and strains were clustered into ethnicity-specific lineages. Yet almost all strains of B. animalis subsp. lactis were incorporated into the same phylogenetic clade, regardless of ethnic origin. Our findings support the hypothesis of co-evolution between human gut symbionts and their respective populations, which is closely linked to the lifestyle of specific bacterial lineages. Hence, the natural and evolutionary history of Bifidobacterium species would be an additional consideration when selecting bifidobacterial strains for industrial and therapeutic applications.

Diversity Analysis of Intestinal Bifidobacteria in the Hohhot Population

(1) Background: Bifidobacterium plays a pivotal role within the gut microbiota, significantly affecting host health through its abundance and composition in the intestine. Factors such as age, gender, and living environment exert considerable influence on the gut microbiota, yet scant attention has been directed towards understanding the specific effects of these factors on the Bifidobacterium population. Therefore, this study focused on 98 adult fecal samples to conduct absolute and relative quantitative analyses of bifidobacteria. (2) Methods: Using droplet digital PCR and the PacBio Sequel II sequencing platform, this study sought to determine the influence of various factors, including living environment, age, and BMI, on the absolute content and biodiversity of intestinal bifidobacteria. (3) Results: Quantitative results indicated that the bifidobacteria content in the intestinal tract ranged from 106 to 109 CFU/g. Notably, the number of bifidobacteria in the intestinal tract of the school population surpassed that of the off-campus population significantly (p = 0.003). Additionally, the group of young people exhibited a significantly higher count of bifidobacteria than the middle-aged and elderly groups (p = 0.041). The normal-weight group displayed a significantly higher bifidobacteria count than the obese group (p = 0.027). Further analysis of the relative abundance of bifidobacteria under different influencing factors revealed that the living environment emerged as the primary factor affecting the intestinal bifidobacteria structure (p = 0.046, R2 = 2.411). Moreover, the diversity of bifidobacteria in the intestinal tract of college students surpassed that in the out-of-school population (p = 0.034). This was characterized by a notable increase in 11 strains, including B. longum, B. bifidum, and B. pseudolongum, in the intestinal tract of college students, forming a more intricate intestinal bifidobacteria interaction network. (4) Conclusions: In summary, this study elucidated the principal factors affecting intestinal bifidobacteria and delineated their characteristics of intestinal bifidobacteria in diverse populations. By enriching the theory surrounding gut microbiota and health, this study provides essential data support for further investigations into the intricate dynamics of the gut microbiota.

Dynamics of the Gut Microbiota and Faecal and Serum Metabolomes during Pregnancy-A Longitudinal Study

Normal pregnancy involves numerous physiological changes, including changes in hormone levels, immune responses, and metabolism. Although several studies have shown that the gut microbiota may have an important role in the progression of pregnancy, these findings have been inconsistent, and the relationship between the gut microbiota and metabolites that change dynamically during and after pregnancy remains to be clarified. In this longitudinal study, we comprehensively profiled the temporal dynamics of the gut microbiota, Bifidobacterium communities, and serum and faecal metabolomes of 31 women during their pregnancies and postpartum periods. The microbial composition changed as gestation progressed, with the pregnancy and postpartum periods exhibiting distinct bacterial community characteristics, including significant alterations in the genera of the Lachnospiraceae or Ruminococcaceae families, especially the Lachnospiraceae FCS020 group and Ruminococcaceae UCG-003. Metabolic dynamics, characterised by changes in nutrients important for fetal growth (e.g., docosatrienoic acid), anti-inflammatory metabolites (e.g., trans-3-indoleacrylic acid), and steroid hormones (e.g., progesterone), were observed in both serum and faecal samples during pregnancy. Moreover, a complex correlation was identified between the pregnancy-related microbiota and metabolites, with Ruminococcus1 and Ruminococcaceae UCG-013 making important contributions to changes in faecal and serum metabolites, respectively. Overall, a highly coordinated microbiota-metabolite regulatory network may underlie the pregnancy process. These findings provide a foundation for enhancing our understanding of the molecular processes occurring during the progression of pregnancy, thereby contributing to nutrition and health management during this period.

Bifidobacterium animalis subsp. lactis boosts neonatal immunity: unravelling systemic defences against Salmonella

Bifidobacterium animalis subsp. lactis may be a useful probiotic intervention for regulating neonatal intestinal immune responses and counteracting Salmonella infection. However, recent research has focused on intestinal immunity, leaving uncertainties regarding the central, peripheral, and neural immune responses in neonates. Therefore, this study investigated the role and mechanisms of B. animalis subsp. lactis in the systemic immune responses of neonatal rats following Salmonella infection. Through extremely early pretreatment with B. animalis subsp. lactis (6 hours postnatal), the neonatal rat gut microbiota was effectively reshaped, especially the Bifidobacterium community. In the rats pretreated with B. animalis subsp. lactis, Salmonella was less prevalent in the blood, liver, spleen, and intestines following infection. The intervention promoted T lymphocyte subset balance in the spleen and thymus and fostered neurodevelopment and neuroimmune balance in the brain. Furthermore, metabolic profiling showed a strong correlation between the metabolites in the serum and colon, supporting the view that B. animalis subsp. lactis pretreatment influences the systemic immune response by modifying the composition and metabolism of the gut microbiota. Overall, the results imply that B. animalis subsp. lactis pretreatment, through the coordinated regulation of colonic and serum metabolites, influences the systemic immune responses of neonatal rats against Salmonella infection.

Interactions between wheat germ polysaccharide and gut microbiota through in vitro batch fecal fermentation and an aging mice model: Targeting enrichment of Bacteroides uniformis and Bifidobacterium pseudocatenulatum

The interaction between wheat germ polysaccharide (WGP) and gut microbiota remains relatively less investigated. Thus, this study explored their interaction via in vitro batch fecal fermentation. WGP elevated dramatically the relative abundances of Bacteroides (especially Ba. xylanisolvens, Ba. uniformis, and Ba. intestinalis), Bifidobacterium (especially Bi. pseudocatenulatum) and Eubacterium, and decreased Alistipes, Klebsiella, Bilophila and Sutterella. Moreover, the metabolomics and Spearman correlation results showed that these alterations in gut microbiota gave rise to over 13-fold augmentation in the quantities of short-chain fatty acids (SCFAs) and indole-3-lactic acid, as well as 7.17- and 4.23-fold increase in acetylcholine and GABA, respectively, at 24 h of fermentation. Interestingly, PICRUSt analysis showed that WGP markedly reduced aging pathway, and enriched nervous system pathway. Therefore, the D-gal-induced aging mice model was used to further verify these effects. The results demonstrated that WGP had a protective effect on D-gal-induced behavioral deficits, particularly in locomotor activity, and spatial and recognition memory. WGP elevated dramatically the relative abundances of Bacteroides (especially Ba. sartorii and Ba. uniformis), Bifidobacterium (especially Bi. pseudocatenulatum) and Parabacteroides, and decreased Alistipes and Candidatus Arthromitus. These findings highlight the potential utility of WGP as a dietary supplement for retarding the aging process and mitigating age-associated learning and memory decline via the targeted enrichment of Bacteroides and Bifidobacterium and the related metabolites.

Population-level variation in gut bifidobacterial composition and association with geography, age, ethnicity, and staple food

Bifidobacteria are key gut commensals that confer various health benefits and are commonly used as probiotics. However, little is known about the population-level variation in gut bifidobacterial composition and its affecting factors. Therefore, we analyzed Bifidobacterium species with amplicon sequencing of the groEL gene on fecal samples of 1674 healthy individuals, who belonged to eight ethnic groups and resided in 60 counties/cities of 28 provinces across China. We found that the composition of the bifidobacterial community was associated with geographical factors, demographic characteristics, staple food type, and urbanization. First, geography, which reflects a mixed effect of other variables, explained the largest variation in the bifidobacterial profile. Second, middle adolescence (age 14-17) and age 30 were two key change points in the bifidobacterial community development, and a bifidobacterial community resembling that of adults occurred in middle adolescence, which is much later than the maturation of the whole gut microbial community at approximately age 3. Third, each ethnicity showed a distinct bifidobacterial profile, and the remarkable amount of unknown Bifidobacterium species in the Tibetan gut suggested undiscovered biodiversity. Fourth, wheat as the main staple food promoted the flourish of B. adolescentis and B. longum. Fifth, alpha diversity of the bifidobacterial community decreased with urbanization. Collectively, our findings provide insight into the environmental and host factors that shape the human gut bifidobacterial community, which is fundamental for precision probiotics.

The microbiome and gene expression of honey bee workers are affected by a diet containing pollen substitutes

Pollen is the primary source of dietary protein for honey bees. It also includes complex polysaccharides in its outer coat, which are largely indigestible by bees but can be metabolized by bacterial species within the gut microbiota. During periods of reduced availability of floral pollen, supplemental protein sources are frequently provided to managed honey bee colonies. The crude proteins in these supplemental feeds are typically byproducts from food manufacturing processes and are rarely derived from pollen. Our experiments on the impact of different diets showed that a simplified pollen-free diet formulated to resemble the macronutrient profile of a monofloral pollen source resulted in larger microbial communities with reduced diversity, reduced evenness, and reduced levels of potentially beneficial hive-associated bacteria. Furthermore, the pollen-free diet sharply reduced the expression of genes central to honey bee development. In subsequent experiments, we showed that these shifts in gene expression may be linked to colonization by the gut microbiome. Lastly, we demonstrated that for bees inoculated with a defined gut microbiota, those raised on an artificial diet were less able to suppress infection from a bacterial pathogen than those that were fed natural pollen. Our findings demonstrate that a pollen-free diet significantly impacts the gut microbiota and gene expression of honey bees, indicating the importance of natural pollen as a primary protein source.

Effect of Agaricus bisporus Polysaccharides on Human Gut Microbiota during In Vitro Fermentation: An Integrative Analysis of Microbiome and Metabolome

Agaricus bisporus polysaccharide (ABP) is an important active component in edible mushrooms, but its interaction with gut microbiota is unclear. Therefore, this study evaluated the effect of ABP on the composition and metabolites of human gut microbiota by in vitro batch fermentation. The main degrading bacteria for ABP were Bacteroides, Streptococcus, Enterococcus, Paraprevotella, Bifidobacterium, Lactococcus, Megamonas, and Eubacterium, whose relative abundances increased during 24 h of in vitro fermentation. The short-chain fatty acids (SCFAs) content also increased more than 15-fold, accordingly. Moreover, the effects of ABP on the relative abundance of Bacteroides (Ba.) and Bifidobacterium (Bi.) at the species level were further determined. ABP can enrich Ba. thetaiotaomicron, Ba. intestinalis, Ba. uniformis, and Bi. longum. PICRUSt analysis revealed that the catabolism of ABP was accompanied by changes in the metabolism of carbohydrates, nucleotides, lipids and amino acids, which were also supported by metabonomic results. It is worth mentioning that, after 24 h fermentation, the relative amounts of gamma-aminobutyric acid (GABA), nicotinamide and nicotinamide adenine dinucleotide (NAD+) had 14.43-, 11.34- and 15.36-fold increases, respectively, which were positively related to Bacteroides (Ba. thetaiotaomicron, Ba. intestinalis), Streptococcus, and Bi. longum (|r| > 0.98). These results laid the research foundation for exploring ABP as a potential prebiotic or dietary supplement for the targeted regulation of gut microbiota or metabolites.

Agaricus bisporus Polysaccharides Ameliorates Behavioural Deficits in D-Galactose-Induced Aging Mice: Mediated by Gut Microbiota

White button mushroom polysaccharide (WMP) has various health-promoting functions. However, whether these functions are mediated by gut microbiota has not been well explored. Therefore, this study evaluated the anti-aging capacity of WMP and its effects on the diversity and composition of gut microbiota in D-galactose-induced aging mice. WMP significantly improved locomotor activity and the spatial and recognition memory of the aging mice. It also alleviated oxidative stress and decreased the pro-inflammatory cytokine levels in the brain. Moreover, WMP increased α-diversity, the short-chain fatty acid (SCFA) level and the abundance of beneficial genera, such as Bacteroides and Parabacteroides. Moreover, its effect on Bacteroides at the species level was further determined, and the enrichments of B. acidifaciens, B. sartorii and B. stercorirosoris were found. A PICRUSt analysis revealed that WMP had a greater impact on the metabolism of carbon, fatty acid and amino acid, as well as the MAPK and PPAR signaling pathway. In addition, there was a strong correlation between the behavioral improvements and changes in SCFA levels and the abundance of Bacteroides, Parabacteroides, Mucispirillum and Desulfovibrio and Helicobacter. Therefore, WMP might be suitable as a functional foods to prevent or delay aging via the directed enrichment of specific species in Bacteroides.

Assessment of the role and mechanism of Bifidobacterium animalis subsp. lactis isolated from neonates' feces in protecting neonatal rats from Salmonella infection

OBJECTIVES

It is now well known that Bifidobacterium animalis subsp. lactis (B. lactis), an important early-life colonizer of the gut, provides immune-related benefits to infants. The aim of the work is to explore the intraspecific resistance to Salmonella infection of B. lactis isolated from neonatal feces, and to learn more insights into how B. lactis mediates beneficial roles in early-life infection resistance.

METHODS

Five strains of B. lactis (NFBAL11/NFBAL23/NFBAL44/NFBAL63/NFBAL92) were screened from fecal samples of neonates born within fifteen days and pretreated neonatal rats prior to infection with Salmonella typhimurium (S. typhimurium) SL1344. The survival rate, fecal occult blood, diarrhea and hepatosplenomegaly were detected to assess the ability of B. lactis to prevent S. typhimurium infection. Furthermore, the structure of mucus layer, gene expression, cytokine levels, antioxidant levels and intestinal microflora composition were detected to explore the mechanism.

RESULTS

All strains showed activity against S. typhimurium, with B. lactis NFBAL23 being the most active, followed by NFBAL63 and NFBAL92. And these advantages weren't attained by enhancing physical growth and development. Mechanistically, the neonatal rats treated with B. lactis (NFBAL23/NFBAL63/NFBAL92) had improved intestinal barrier function involving physical, chemical, immune and biological barriers in the face of challenges posed by S. typhimurium.

CONCLUSIONS

These findings revealed the intraspecific difference, beneficial roles and mechanisms of action of B. lactis against Salmonella infection early in life, which highlighted the necessity of supplementing appropriate B. lactis, and provided several potential B. lactis candidates for Salmonella infection treatment.

Assessment of the bifidogenic and antibacterial activities of xylooligosaccharide

Xylooligosaccharide (XOS) is an attractive prebiotic mainly due to its bifidogenic effect. However, commercial XOS with different compositions is often applied in the food industry at different doses without specifications. In this study, we evaluated the bifidogenic activity of XOS at different doses with either mixtures or pure fractions with different degrees of polymerization (DP), using three strains of Bifidobacterium spp., including B. breve ATCC 15700, B. bifidum ATCC 29521, and B. animalis subsp. lactis HN019. Three growth indicators showed strain-specific bifidogenic activity of XOS, and the activity was both dose- and fraction-dependent as only certain fractions stimulated significant growth. Adding 0.25% XOS (w/v) also promoted increase in total bifidobacterial population of rat fecal samples fermented in vitro. Albeit the antibacterial activity of XOS fractions can be demonstrated, significant growth inhibition can only be achieved when 4.0% XOS mixture was added in Staphylococcus aureus ATCC 6538 pure culture. In contrast, in the presence of B. lactis HN019, 1.0% XOS showed significant antibacterial activity against S. aureus ATCC 6538 in milk. In addition, RNA sequencing suggested downregulation of genes involved in S. aureus ATCC 6538 infection, pathogenesis, and quorum sensing, by XOS. In conclusion, the report urges scientific specifications on XOS chemistry for its effective application as a novel food ingredient or functional food and provides novel insights into its bifidogenic and antibacterial activities.

The Comparative Analysis of Genomic Diversity and Genes Involved in Carbohydrate Metabolism of Eighty-Eight Bifidobacterium pseudocatenulatum Isolates from Different Niches of China

Eighty-eight Bifidobacterium pseudocatenulatum strains, which were isolated from human, chicken and cow fecal samples from different niches of China, were compared genomically in this study to evaluate their diversity. It was found that B. pseudocatenulatum displayed a closed pan-genome, including abundant glycoside hydrolase families of the carbohydrate active enzyme (CAZy). A total of 30 kinds of glycoside hydrolases (GHs), 14 kinds of glycosyl transferases (GTs), 13 kinds of carbohydrate-binding modules (CBMs), 6 kinds of carbohydrate-esterases (CEs), and 2 kinds of auxiliary activities (AAs) gene families were identified across the genomes of the 88 B. pseudocatenulatum strains. Specifically, this showed that significant differences were also present in the number of 10 carbohydrate-active enzyme gene families (GT51, GH13_32, GH26, GH42, GH121, GH3, AA3, CBM46, CE2, and CE6) among the strains derived from the hosts of different age groups, particularly between strains from infants and those from other human age groups. Twelve different individuals of B. pseudocatenulatum from four main clusters were selected for further study to reveal the genetic diversity of carbohydrate metabolism-related genes within the same phylogenetics. The animal experiment showed that 3 weeks of oral administration and 1 week after cessation of administration of these strains did not markedly alter the serum routine inflammatory indicators in mice. Furthermore, the administration of these strains did not significantly cause adverse changes in the gut microbiota, as indicated by the α- and β-diversity indexes, relative to the control group (normal diet). Beyond that, FAHBZ9L5 significantly increased the abundance of B. pseudocatenulatum after 3 weeks and significantly increased the abundance of acetic acid and butyric acid in the host’s intestinal tract 3 and 4 weeks after the first administration, respectively, compared with the control group. Corresponding to this, comparative genomic analyses of 12 B. pseudocatenulatum suggest that FAHBZ9L5-specific genes were rich in ABC transporters and carbohydrate esterase. Combining the results of comparative genomics analyses and animal experiment, it is suggested that the strains containing certain gene clusters contribute to another competitive growth advantage of B. pseudocatenulatum, which facilitates its intestinal carbohydrate metabolism in a host.

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

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.

A randomised, double-blind, placebo-controlled trial of Bifidobacterium bifidum CCFM16 for manipulation of the gut microbiota and relief from chronic constipation

A variety of opinions exist on the potential of probiotics to provide relief from chronic constipation with much focus being placed on their mechanism of action and causes of heterogeneity in the results of different studies. We aimed to determine the efficacy and safety of ingesting Bifidobacterium bifidum (B. bifidum) CCFM16 for 28 days to relieve constipation and to understand the mechanism of action. Using Rome IV criterion, 53 and 50 participants diagnosed with chronic constipation were included in the probiotic group and placebo group, respectively. Spontaneous bowel movements (SBMs) per week, stool consistency (Bristol Stool Form Scale [BSFS]), the proportion of SBM responders, patient assessment of constipation symptoms (PAC-SYM), and quality of life (PAC-QoL) were evaluated. The gut microbiota, short-chain fatty acids (SCFAs) and other indicators were also assessed. B. bifidum CCFM16 treatment improved the stool consistency and increased the proportion of SBM responders, but the differences in PAC-SYM and PAC-QoL were statistically insignificant between the groups. Analysis of the SCFAs and microbiome revealed that CCFM16 significantly increased the acetic acid and butyric acid concentrations and enhanced the Firmicutes/Bacteroidetes ratio. Levels of Clostridia were particularly increased and were associated with the increase in butyric acid. In addition, we found the other side of Clostridia; several taxa in the order Clostridiales were observed to prevent CCFM16 from proper functioning in the pre-treatment microbiome. In conclusion, CCFM16 can potentially and efficaciously relieve chronic constipation in Chinese adults by regulating the gut microbiota and SCFA metabolism. The two sides of Clostridia illustrate its importance in microbial therapy for constipation.

Differential Response of Bacterial Microdiversity to Simulated Global Change

Global change experiments often observe shifts in bacterial community composition based on 16S rRNA gene sequences. However, this genetic region can mask a large amount of genetic and phenotypic variation among bacterial strains sharing even identical 16S regions. As such, it remains largely unknown whether variation at the sub-16S level, sometimes termed microdiversity, responds to environmental perturbations and whether such changes are relevant to ecosystem processes. Here, we investigated microdiversity within Curtobacterium, the dominant bacterium found in the leaf litter layer of soil, to simulated drought and nitrogen addition in a field experiment. We first developed and validated Curtobacterium-specific primers of the groEL gene to assess microdiversity within this lineage. We then tracked the response of this microdiversity to simulated global change in two adjacent plant communities, grassland and coastal sage scrub (CSS). Curtobacterium microdiversity responded to drought but not nitrogen addition, indicating variation within the genus of drought tolerance but not nitrogen response. Further, the response of microdiversity to drought depended on the ecosystem, suggesting that litter substrate selects for a distinct composition of microdiversity that is constrained in its response, perhaps related to tradeoffs in resource acquisition traits. Supporting this interpretation, a metagenomic analysis revealed that the composition of Curtobacterium-encoded CAZymes varied distinctly across the two ecosystems. Identifying the degree to which relevant traits are phylogenetically conserved may help to predict when the aggregated response of a 16S-defined taxon masks differential responses of finer-scale bacterial diversity to global change. Importance Microbial communities play an integral role in global biogeochemical cycling, but our understanding of how global change will affect microbial community structure and functioning remains limited. Microbiome analyses typically aggregate large amounts of genetic diversity which may obscure finer variation in traits. This study found that fine-scale diversity (or microdiversity) within the bacterial genus, Curtobacterium, was affected by simulated global changes. However, the degree to which this was true depended on the type of global change as the composition of Curtobacterium microdiversity was affected by drought, but not by nitrogen addition. Further, these changes were associated with variation in carbon degradation traits. Future work might improve predictions of microbial community responses to global change by considering microdiversity.

Effect of an infant formula containing sn-2 palmitate on fecal microbiota and metabolome profiles of healthy term infants: a randomized, double-blind, parallel, controlled study

Different infant diets have strong effects on child development and may engender variations in fecal microbiota and metabolites. The objective of this study was to evaluate the effect of an infant formula containing sn-2 palmitate on fecal microbiota and metabolites in healthy term infants. The study involved three groups as indicated below. Investigational: the group fed a formula containing high sn-2 palmitate for 16 weeks. Control: the group fed a formula using a regular vegetable oil for 16 weeks. Breastfed: the group fed breast milk for 16 weeks. Fecal samples were collected at 8 weeks (n = 35, 37, and 35, respectively) and 16 weeks (n = 30, 32, and 30, respectively) for the control, investigational, and breastfed infants. Microbiota data were obtained using 16S rRNA sequencing. Short-chain fatty acid (SCFA) analysis was performed using GC-MS, and untargeted metabolomics was conducted using LC-MS. The effect of the formula containing sn-2 palmitate was different from that of the control formula on microbiota and metabolites. Sn-2 palmitate promoted the proliferation of Bifidobacterium and reduced the abundance of Escherichia-Shigella at 8 weeks. Furthermore, it increased α-diversity and enhanced acetate content in feces at both 8 and 16 weeks. In the investigational group infants, the abundance of DL-tryptophan, indole-3-acrylic acid, acetyl-β-methylcholine, L-methionine, and 2-hydroxyvaleric acid significantly increased at 8 weeks, while a notable increase in the abundance of 3-phenyllactic acid, palmitic acid, L-phenylalanine, and leucylproline was observed at 16 weeks. In addition, compared with that of the control infants, the intestinal microbiota and metabolites of sn-2 palmitate-supplemented infants were more similar to those of the breastfed infants. The study hopes to provide a scientific basis for the development of functional infant formulas in the future.

Efficacy of Probiotic Compounds in Relieving Constipation and Their Colonization in Gut Microbiota

A number of studies have confirmed the relationship between constipation and gut microbiota. Additionally, many human and animal experiments have identified probiotics as effectors for the relief of constipation symptoms. In this study, probiotic compounds, including Lactobacillus acidophilus LA11-Onlly, Lacticaseibacillus rhamnosus LR22, Limosilactobacillus reuteri LE16, Lactiplantibacillus plantarum LP-Onlly, and Bifidobacterium animalis subsp. lactis BI516, were administered to mice with loperamide-induced constipation, and the impacts of these strains on constipation-related indicators and gut microbiota were evaluated. The effects of probiotic compounds on constipation relief were associated with various aspects, including gastrointestinal transit rate, number and weight of stools, serum and intestinal gastrointestinal regulatory hormones, and serum cytokines. Some of the probiotic compounds, including Limosilactobacillus reuteri, Lactiplantibacillus plantarum, and Lacticaseibacillus rhamnosus, were found to colonize the intestinal tract. Furthermore, higher dosages promoted the colonization of specific strains. This study yields a new perspective for the clinical use of probiotics to improve constipation symptoms by combining strains with different mechanisms for the alleviation of constipation.

Development of gut microbiota and bifidobacterial communities of neonates in the first 6 weeks and their inheritance from mother

Microbiota especially Bifidobacterium play an important role in adjusting and maintaining homeostatic balance within the infant intestine. The aim of this study was to elucidate the relationship between maternal and infant gut microbiota and identify the Bifidobacterium species that may transfer from mother to infant over the first 42 days of the infant's life. Nineteen mother-infant-pair fecal samples were collected and the diversity and composition of the total bacterial and Bifidobacterium communities were analyzed via 16S rDNA and bifidobacterial groEL gene high throughput sequencing. The results revealed that the relative abundance of Bifidobacterium was significantly higher in the infant gut while Parabacteroides, Blautia, Coprococcus, Lachnospira and Faecalibacterium were at lower relative abundance in 7-day and 42-day infant fecal samples compared to the maternal samples. The maternal gut has more B. pseudocatenulatum. In the infant group, B. breve and B. dentium relative abundance increased while B. animalis subsp. lactis decreased from days 7 to 42. Additionally, B. longum subsp. longum isolated from FGZ16 and FGZ35 may have transferred from mother to infant and colonized the infant gut. The results of the current study provide insight toward the infant gut microbiota composition and structure during the first 42 days and may help guide Bifidobacterium supplementation strategies in mothers and infants.

Field-Realistic Tylosin Exposure Impacts Honey Bee Microbiota and Pathogen Susceptibility, Which Is Ameliorated by Native Gut Probiotics

Antibiotics have been applied to honey bee (Apis mellifera) hives for decades to treat Paenibacillus larvae, which causes American foulbrood disease and kills honey bee larvae. One of the few antibiotics approved in apiculture is tylosin tartrate. This study examined how a realistic hive treatment regimen of tylosin affected the gut microbiota of bees and susceptibility to a bacterial pathogen. Tylosin treatment reduced bacterial species richness and phylogenetic diversity and reduced the absolute abundances and strain diversity of the beneficial core gut bacteria Snodgrassella alvi and Bifidobacterium spp. Bees from hives treated with tylosin died more quickly after being fed a bacterial pathogen (Serratia marcescens) in the laboratory. We then tested whether a probiotic cocktail of core bee gut species could bolster pathogen resistance. Probiotic exposure increased survival of bees from both control and tylosin-treated hives. Finally, we measured tylosin tolerance of core bee gut bacteria by plating cultured isolates on media with different tylosin concentrations. We observed highly variable responses, including large differences among strains of both S. alvi and Gilliamella spp. Thus, probiotic treatments using cultured bee gut bacteria may ameliorate harmful perturbations of the gut microbiota caused by antibiotics or other factors. IMPORTANCE The antibiotic tylosin tartrate is used to treat honey bee hives to control Paenibacillus larvae, the bacterium that causes American foulbrood. We found that bees from tylosin-treated hives had gut microbiomes with depleted overall diversity as well as reduced absolute abundances and strain diversity of the beneficial bee gut bacteria Snodgrassella alvi and Bifidobacterium spp. Furthermore, bees from treated hives suffered higher mortality when challenged with an opportunistic pathogen. Bees receiving a probiotic treatment, consisting of a cocktail of cultured isolates of native bee gut bacteria, had increased survival following pathogen challenge. Thus, probiotic treatment with native gut bacteria may ameliorate negative effects of antibiotic exposure.

Shifts in diversity and function of bacterial community during manufacture of Rushan

Rushan is a traditional dairy product consumed by the Bai people in the Yunnan Province of China, and its production still follows the traditional procedure of backslopping. However, how the microbial composition of raw materials and processing shape the microorganisms in Rushan have not been systemically reported. In this study, high-throughput sequencing technique was applied to analyze the microbial compositions of raw milk, fresh Rushan, curd whey, acid whey, and dry Rushan at the phylum, family, genus, and Lactobacillus species levels. The results indicated that Lactobacillus, Lactococcus, and Streptococcus were dominant genera in Rushan, whereas Lactobacillus kefiranofaciens and Lactobacillus helveticus were the 2 abundant species at the Lactobacillus species level. The network analysis indicated that raw milk mainly contributed to the microbial diversity of Rushan, whereas acid whey made a great contribution to shaping the relative abundance of microbes in Rushan and dramatically increased acid-producing genera, such as Lactobacillus and Acetobacter. The variation in microbial composition led to an increase in the relative abundance of pathways related to energy supply, acid production, fatty acid accumulation, cysteine, methionine, and lysine accumulation. The volatile profile of Rushan was rich in esters and acids, and the high relative abundance of Lactobacillus might be associated with reduction of amino acid metabolism, degradation of unpleasant flavored xylene, and accumulation of decanoic, dodecanoic, and tetradecanoic acids in the products. The accumulation of medium long-chain fatty acids might result from the relative abundance of FabF, FabZ, and FabI, particularly from Lactobacillus amylolyticus and Lacticaseibacillus paracasei.

Human gut-derived B. longum subsp. longum strains protect against aging in a D-galactose-induced aging mouse model

BACKGROUND

Probiotics have been used to regulate the gut microbiota and physiology in various contexts, but their precise mechanisms of action remain unclear.

RESULTS

By population genomic analysis of 418 Bifidobacterium longum strains, including 143 newly sequenced in this study, three geographically distinct gene pools/populations, BLAsia1, BLAsia2, and BLothers, were identified. Genes involved in cell wall biosynthesis, particularly peptidoglycan biosynthesis, varied considerably among the core genomes of the different populations, but accessory genes that contributed to the carbohydrate metabolism were significantly distinct. Although active transmission was observed inter-host, inter-country, inter-city, intra-community, and intra-family, a single B. longum clone seemed to reside within each individual. A significant negative association was observed between host age and relative abundance of B. longum, while there was a strong positive association between host age and strain genotype [e.g., single nucleotide polymorphisms in the arginine biosynthesis pathway]. Further animal experiments performed with the B. longum isolates via using a D-galactose-induced aging mouse model supported these associations, in which B. longum strains with different genotypes in arginine biosynthesis pathway showed divergent abilities on protecting against host aging possibly via their different abilities to modify the metabolism of gut microbes.

CONCLUSIONS

This is the first known example of research on the evolutionary history and transmission of this probiotic species. Our results propose a new mechanistic insight for promoting host longevity via the informed use of specific probiotics or molecules. Video abstract.

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

Breast milk acts as an intermediary for the transfer of functionally important commensal bacteria from mother to infant, especially for Bifidobacterium that can colonize the infant gut. However, the vast majority of rRNA amplicon-based studies reported the conspicuous intercohort and interindividual variation for the prevalence of Bifidobacterium in breast milk. In order to elucidate whether Bifidobacterium phylotypes persistently co-occured at the species or strain level in mother–breast milk–infant triads, we analyzed collectively the next-generation sequencing (NGS) datasets of bacterial 16S rRNA gene and the Bifidobacterium-specific groEL gene from maternal feces, breast milk, and infant feces in a small yet very homogeneous cohort of 25 healthy Uyghur mother–infant pairs (lactation for 7–720 days) in Kashgar, Xinjiang, China. Overall, 16S rRNA gene analysis showed that microbiome in the newborn gut was closer to that of breast milk in the first 4 months of lactation, and subsequently showed an obvious trend of adulthood at 6–12 months. Based on the BLAST accurate taxonomic result of the representative sequences of all ASVs (amplicon sequencing variants), only three sets of ASVs could be clearly assigned into Bifidobacterium species, whereas the remaining eight sets of ASVs corresponded to four indefinite Bifidobacterium species group. By contrast, the groEL gene dataset was partitioned into 376 ASVs, at least belonging to 13 well-known Bifidobacterium species or subspecies, of which 15 ASVs, annotated to seven well-known Bifidobacterium species or subspecies, showed triadic synchronism in most 23 mother–infant pairs tested. However, several other rare bifidobacterial phylotypes, which were frequently encountered in animals, were found to display no correspondence of the presence between the three ecosystems of mother–infant pairs. Our test results were obviously to support the hypothesis that breast milk acts as an intermediary for the transfer of probiotic commensal bacteria from mother to infant, especially for endosymbiotic Bifidobacterium that can colonize the infant gut. Some oxygen-insensitive exogenous Bifidobacterium phylotypes with a cosmopolitan lifestyle may be indirectly transferred to breast milk and the infant’s intestinal tract through environmental contamination. Thus, the groEL gene proved to be a very effective target for the depth resolution of Bifidobacterium community by high-throughput sequencing technologies.

Biodiversity of Ligilactobacillus salivarius Strains from Poultry and Domestic Pigeons

Simple Summary

Ligilactobcillus salivarius is a Gram-positive bacterium that commonly colonizes the mucous membranes of the digestive tracts of humans and animals, including birds. It belongs to the group of lactic acid bacteria which, by producing lactic acid, acidify the intestinal environment and limit the development of undesirable intestinal microflora. In addition, L. salivarius can produce other antimicrobial substances, such as bacteriocins and hydrogen peroxide. Due to limiting the development of unfavourable microflora and other health-promoting effects, L. salivarius bacteria are considered as potential probiotics that may increase animal health, and thus animal production indicators. In this work, we undertook research on the characteristics of L. salivarius strains from chickens, geese, turkeys and domestic pigeons. We showed great variation in phenotypic and genotypic traits between strains and the evolutionary adaptation of L. salivarius strains to the colonization of a specific host. The results of the study contribute to knowledge of the characteristics of the species L. salivarius and may be useful in the selection of probiotic strains.

Abstract

Ligilactobacillus salivarius is an important member of the human and animal gut microbiota, and selected strains are promising probiotics, but knowledge of the characteristics of avian isolates is still limited. In this study, we examined selected phenotypic and genotypic traits of 33 L. salivarius strains from geese, chickens, turkeys and pigeons. The strains varied in terms of cell size, colony morphology, broth growth characteristics, biofilm formation, tolerance to bile, hydrophobicity and phenotypic and genotypic antibiotic resistance profiles. Large variation among strains was noted for the utilization of sorbitol, salicin, trehalose, rhamnose, inulin and N-acetyl-D-glucosamine. The presence of genes related to sugar metabolism, i.e., mipB, tktA, rhaB and LSL_1894, was not always correlated with the biochemical phenotypic profile. Correlations were recorded between the host and utilization of certain sugars as well as tolerance to bile. The repA-type megaplasmid and genes coding for Abp118 bacteriocin were detected in 94% and 51.5% of L. salivarius strains, respectively. Phylogeny based on groEL gene sequences was partly correlated with the origin of the strains and revealed an evolutionary distance between L. salivarius strains from humans and birds. The results of the study contribute to knowledge of the characteristics of the species L. salivarius. Intraspecies variations of L. salivarius strains may affect their ability to colonize specific niches and utilize nutrients and reveal potential strain-dependent effects on host health.

High-Fiber, Whole-Food Dietary Intervention Alters the Human Gut Microbiome but Not Fecal Short-Chain Fatty Acids

Dietary shifts can have a direct impact on the gut microbiome by preferentially selecting for microbes capable of utilizing the various dietary nutrients. The intake of dietary fiber has decreased precipitously in the last century, while consumption of processed foods has increased. Fiber, or microbiota-accessible carbohydrates (MACs), persist in the digestive tract and can be metabolized by specific bacteria encoding fiber-degrading enzymes. The digestion of MACs results in the accumulation of short-chain fatty acids (SCFAs) and other metabolic by-products that are critical to human health. Here, we implemented a 2-week dietary fiber intervention aiming for 40 to 50 g of fiber per day within the context of a course-based undergraduate research experience (CURE) (n = 20). By coupling shotgun metagenomic sequencing and targeted gas chromatography-mass spectrometry (GC-MS), we found that the dietary intervention significantly altered the composition of individual gut microbiomes, accounting for 8.3% of the longitudinal variability within subjects. Notably, microbial taxa that increased in relative abundance as a result of the diet change included known MAC degraders (i.e., Bifidobacterium and Lactobacillus). We further assessed the genetic diversity within Bifidobacterium, assayed by amplification of the groEL gene. Concomitant with microbial composition changes, we show an increase in the abundance of genes involved in inositol degradation. Despite these changes in gut microbiome composition, we did not detect a consistent shift in SCFA abundance. Collectively, our results demonstrate that on a short-term timescale of 2 weeks, increased fiber intake can induce compositional changes of the gut microbiome, including an increase in MAC-degrading bacteria.

IMPORTANCE A profound decrease in the consumption of dietary fiber in many parts of the world in the last century may be associated with the increasing prevalence of type II diabetes, colon cancer, and other health problems. A typical U.S. diet includes about ∼15 g of fiber per day, far less fiber than the daily recommended allowance. Changes in dietary fiber intake affect human health not only through the uptake of nutrients directly but also indirectly through changes in the microbial community and their associated metabolism. Here, we conducted a 2-week diet intervention in healthy young adults to investigate the impact of fiber consumption on the gut microbiome. Participants increased their average fiber consumption by 25 g/day on average for 2 weeks. The high-fiber diet intervention altered the gut microbiome of the study participants, including increases in known fiber-degrading microbes, such as Bifidobacterium and Lactobacillus.

A new Illumina MiSeq high-throughput sequencing-based method for evaluating the composition of the Bacteroides community in the intestine using the rpsD gene sequence

Bacteroides is a bacterial genus that is known to closely interact with the host. The potential role of this genus is associated with its ecological status and distribution in the intestine. However, the current 16S V3-V4 region sequencing method can only detect the abundance of this genus, revealing a need for a novel sequencing method that can elucidate the composition of Bacteroides in the human gut microbiota. In this study, a core gene, rpsD, was selected as a template for the design of a Bacteroides-specific primer set. We used this primer set to develop a novel assay based on the Illumina MiSeq sequencing platform that enabled an accurate assessment of the Bacteroides compositions in complex samples. Known amounts of genomic DNA from 10 Bacteroides species were mixed with a complex sample and used to evaluate the performance and detection limit of our assay. The results were highly consistent with those of direct sequencing with a low Bacteroides DNA detection threshold (0.01 ng), supporting the reliability of our assay. In addition, the assay could detect all the known Bacteroides species within the faecal sample. In summary, we provide a sensitive and specific approach to determining the Bacteroides species in complex samples.

A Scoping Review of Research on the Human Milk Microbiome

BACKGROUND

The human milk microbiome is an emerging scientific area. Careful, accurate collection and measurement for microbial sequencing is imperative. There is controversy about a core microbiome, and little is known about factors that influence composition. Even less known are ways that the milk microbiome might seed the infant gut and affect health.

RESEARCH AIM

The aim of this paper is to provide a critical appraisal of milk microbiome research. The four areas of critical appraisal were collection and measurement, composition, effects on composition, and potential health effects for infants related to the milk microbiome.

METHODS

Using a PRISMA-ScR scoping review, we reviewed sources of evidence extracted from PubMed, Web of Science, CINAHL, Academic Search Complete, and PSYCHINFO data sets using the following criteria: English language, published in past 6 years, primary data, and sequencing using Next Generation Sequencing. Charting of sources of evidence included authors, title, journal year, sample, design, and results. The research questions posed were: How is human milk collected and how are the microbes identified? What is the composition and what factors affect the human milk microbiome? What is the relationship of the human milk microbiome to infant biology and health?

RESULTS

The reviewed studies were quantitative, cross sectional, or longitudinal. A core microbiome may be present. The microbiome may seed the early infant gut and promote physiological functions and thus influence human health.

CONCLUSIONS

We have suggested concerns about collection and measurement that lead to gaps in knowledge generation, and mechanistic studies are lacking.

Evaluation of PCR conditions for characterizing bacterial communities with full-length 16S rRNA genes using a portable nanopore sequencer

MinION (Oxford Nanopore Technologies), a portable nanopore sequencer, was introduced in 2014 as a new DNA sequencing technology. MinION is now widely used because of its low initial start-up costs relative to existing DNA sequencers, good portability, easy-handling, real-time analysis and long-read output. However, differences in the experimental conditions used for 16S rRNA-based PCR can bias bacterial community assessments in samples. Therefore, basic knowledge about reliable experimental conditions is needed to ensure the appropriate use of this technology. Our study concerns the reliability of techniques for obtaining accurate and quantitative full-length 16S rRNA amplicon sequencing data for bacterial community structure assessment using MinION. We compared five PCR conditions using three independent mock microbial community standard DNAs and established appropriate, standardized, better PCR conditions among the trials. We then sequenced two mock communities and six environmental samples using Illumina MiSeq for comparison. Modifying the PCR conditions improved the sequencing quality; the optimized conditions were 35 cycles of 95 °C for 1 min, 60 °C for 1 min and 68 °C for 3 min. Our results provide important information for researchers to determine bacterial community using MinION accurately.

Diversity of Gut Microbiota and Bifidobacterial Community of Chinese Subjects of Different Ages and from Different Regions

Gut microbiota composition and functionality are closely linked to host health. In this study, the fecal microbiota and bifidobacterial communities of 111 healthy volunteers from four regions of China of varying age profiles (Child, 1–5 years; Young, 18–50 years; Elder, 60–80 years; Longevity, ≥90 years) were investigated via high-throughput sequencing. Canonical analysis revealed that the gut microbiota, as well as bifidobacteria profiles of the subjects, clustered according to their regions and age. Eight genera were shared among all subjects, however, certain genera distributed differently in subjects grouped by region and age. Faecalibacterium was enriched in samples from Zhongxiang, unclassified Ruminococcaceae and Christensenellaceae were enriched in the Longevity group, and Bifidobacterium was enriched in Child. Within Bifidobacterium, B. longum was the most abundant species in almost all samples except for Child, in which B. pseudocatenulatum was the most abundant. Additionally, the abundances of B. adolescentis and B. dentium were lower in Child. In conclusion, our results suggest that geography and age affect the structure of the gut microbiota, as well as Bifidobacterium composition, and this variation may greatly associate with the metabolic and immune changes that occur during the process of aging.

groEL Gene-Based Phylogenetic Analysis of Lactobacillus Species by High-Throughput Sequencing

Lactobacillus is a fairly diverse genus of bacteria with more than 260 species and subspecies. Many profiling methods have been developed to carry out phylogenetic analysis of this complex and diverse genus, but limitations remain since there is still a lack of comprehensive and accurate analytical method to profile this genus at species level. To overcome these limitations, a Lactobacillus-specific primer set was developed targeting a hypervariable region in the groEL gene-a single-copy gene that has undergone rapid mutation and evolution. The results showed that this methodology could accurately perform taxonomic identification of Lactobacillus down to the species level. Its detection limit was as low as 10⁴ colony-forming units (cfu)/mL for Lactobacillus species. The assessment of detection specificity using the Lactobacillus groEL profiling method found that Lactobacillus, Pediococcus, Weissella, and Leuconostoc genus could be distinguished, but non-Lactobacillus Genus Complex could not be detected. The groEL gene sequencing and Miseq high-throughput approach were adopted to estimate the richness and diversity of Lactobacillus species in different ecosystems. The method was tested using kurut (fermented yak milk) samples and fecal samples of human, rat, and mouse. The results indicated that Lactobacillus mucosae was the predominant gut Lactobacillus species among Chinese, and L. johnsonii accounted for the majority of lactobacilli in rat and mouse gut. Meanwhile, L. delbrueckii subsp. bulgaricus had the highest relative abundance of Lactobacillus in kurut. Thus, this groEL gene profiling method is expected to promote the application of Lactobacillus for industrial production and therapeutic purpose.

Bifidobacterium and Lactobacillus Composition at Species Level and Gut Microbiota Diversity in Infants before 6 Weeks

Our objective was to investigate the effects of different delivery and feeding modes on the gut microbiota composition of early infants with special emphasis on Bifidobacterium and Lactobacillus profiles at species level. 16S rRNA V3-V4 regions, bifidobacterial, and lactobacilli groEL genes from infant feces were sequenced by Illumina MiSeq. Gut microbiota abundance was significantly different, where standard vaginally delivered (SVD) and breast-fed (BF) groups were higher in comparison with caesarean section (CS), milk-powder-fed (MPF), and mixed-fed (MF) groups. The genus unclassified Enterobacteriaceae was dominant, followed by Bifidobacterium, which was highly abundant in SVD and BF groups. The dominant Bifidobacterium species in all groups were B. longum subsp. longum, B. longum subsp. infantis and B. animalis subsp. lactis. B. dentium and the diversity of Bifidobacterium in SVD and BF groups were significantly higher. For Lactobacillus profiles, L. rhamnosus and L. gasseri were dominant among all the groups, while Lactobacillus species in CS and MPF groups were more diverse. Functional predictions showed significant differences between delivery mode and feeding groups, such as phosphotransferase system as well as taurine and hypotaurine metabolism. In early infants with different delivery and feeding methods, gut microbiota-particularly bifidobacteria and lactobacilli communities-showed significant differences, with strong implications for physiological functions.

Effects of Different Doses of Fructooligosaccharides (FOS) on the Composition of Mice Fecal Microbiota, Especially the Bifidobacterium Composition

Fructooligosaccharides (FOS) are a well-known class of prebiotic and are considered to selectively stimulate the growth of bifidobacteria in the gut. Previous studies focused on the growth stimulation of Bifidobacterium, but they did not further investigate the bifidobacterial composition and the specific species that were stimulated. In this study, mice were fed with FOS in different doses for four weeks and the composition of fecal microbiota, in particular Bifidobacterium, was analyzed by sequencing the V3–V4 region and the groEL gene on the MiSeq platform, respectively. In the high-dose group, the relative abundance of Actinobacteria was significantly increased, which was mainly contributed by Bifidobacterium. At the genus level, the relative abundances of Blautia and Coprococcus were also significantly increased. Through the groEL sequencing, 14 species of Bifidobacterium were identified, among which B. pseudolongum was most abundant. After FOS treatment, B. pseudolongum became almost the sole bifidobacterial species (>95%). B. pseudolongum strains were isolated and demonstrated their ability to metabolize FOS by high performance liquid chromatography (HPLC). Therefore, we inferred that FOS significantly stimulated the growth of B. pseudolongum in mice. Further investigations are needed to reveal the mechanism of selectiveness between FOS and B. pseudolongum, which would aid our understanding of the basic principles between dietary carbohydrates and host health.