Living in a bottle: Bacteria from sediment-associated Mediterranean waste and potential growth on polyethylene terephthalate.

Ocean pollution is a worldwide environmental challenge that could be partially tackled through microbial applications. To shed light on the diversity and applications of the bacterial communities that inhabit the sediments trapped in artificial containers, we analyzed residues (polyethylene terephthalate [PET] bottles and aluminum cans) collected from the Mediterranean Sea by scanning electron microscopy and next generation sequencing. Moreover, we set a collection of culturable bacteria from the plastisphere that were screened for their ability to use PET as a carbon source. Our results reveal that Proteobacteria are the predominant phylum in all the samples and that Rhodobacteraceae, Woeseia, Actinomarinales, or Vibrio are also abundant in these residues. Moreover, we identified marine isolates with enhanced growth in the presence of PET: Aquimarina intermedia, Citricoccus spp., and Micrococcus spp. Our results suggest that the marine environment is a source of biotechnologically promising bacterial isolates that may use PET or PET additives as carbon sources.

Novel Mechanism and Kinetics of Tetramethrin Degradation Using an Indigenous Gordonia cholesterolivorans A16.

Tetramethrin is a pyrethroid insecticide that is commonly used worldwide. The toxicity of this insecticide into the living system is an important concern. In this study, a novel tetramethrin-degrading bacterial strain named A16 was isolated from the activated sludge and identified as Gordonia cholesterolivorans. Strain A16 exhibited superior tetramethrin degradation activity, and utilized tetramethrin as the sole carbon source for growth in a mineral salt medium (MSM). High-performance liquid chromatography (HPLC) analysis revealed that the A16 strain was able to completely degrade 25 mg·L-1 of tetramethrin after 9 days of incubation. Strain A16 effectively degraded tetramethrin at temperature 20-40 °C, pH 5-9, and initial tetramethrin 25-800 mg·L-1. The maximum specific degradation rate (qmax), half-saturation constant (Ks), and inhibition constant (Ki) were determined to be 0.4561 day-1, 7.3 mg·L-1, and 75.2 mg·L-1, respectively. The Box-Behnken design was used to optimize degradation conditions, and maximum degradation was observed at pH 8.5 and a temperature of 38 °C. Five intermediate metabolites were identified after analyzing the degradation products through gas chromatography-mass spectrometry (GC-MS), which suggested that tetramethrin could be degraded first by cleavage of its carboxylester bond, followed by degradation of the five-carbon ring and its subsequent metabolism. This is the first report of a metabolic pathway of tetramethrin in a microorganism. Furthermore, bioaugmentation of tetramethrin-contaminated soils (50 mg·kg-1) with strain A16 (1.0 × 107 cells g-1 of soil) significantly accelerated the degradation rate of tetramethrin, and 74.1% and 82.9% of tetramethrin was removed from sterile and non-sterile soils within 11 days, respectively. The strain A16 was also capable of efficiently degrading a broad spectrum of synthetic pyrethroids including D-cyphenothrin, chlorempenthrin, prallethrin, and allethrin, with a degradation efficiency of 68.3%, 60.7%, 91.6%, and 94.7%, respectively, after being cultured under the same conditions for 11 days. The results of the present study confirmed the bioremediation potential of strain A16 from a contaminated environment.

Probiotics, Prebiotics, and Synbiotics in the Irritable Bowel Syndrome Treatment: A Review.

Irritable bowel syndrome is not a life-threatening disease, yet it significantly affects the quality of life and contributes to economic loss. It is estimated that even up to 45% of the world's population can suffer from the disease. The first attempts to diagnose irritable bowel syndrome were made at the end of the 19th century; however, establishing appropriate diagnostic criteria and treatment methods is still ongoing. To date, little is known about the etiology of irritable bowel syndrome; however, growing attention is drawn to the intestinal microbiota as a factor in the disease development. For this reason, researchers have conducted many studies on therapies that modulate the microbiota, among which probiotics, prebiotics, and synbiotics are widely studied. To date, most studies have examined probiotics; however, there are also several studies demonstrating the efficacy of prebiotics and synbiotics. The aim of this review was to summarize findings on the usefulness of probiotics, prebiotics, and synbiotics in the treatment of irritable bowel syndrome.

Evaluation of Rpf protein of Micrococcus luteus for cultivation of soil actinobacteria.

Rpf protein, a kind of resuscitation promoting factor, was first found in the culture supernatant of Micrococcus luteus. It can resuscitate the growth of M. luteus in "viable but non-culture, VBNC" state and promote the growth of Gram-positive bacteria with high G + C content. This paper investigates the resuscitating activity of M. luteus ACCC 41016T Rpf protein, which was heterologously expressed in E. coli, to cells of M. luteus ACCC 41016T and Rhodococcus marinonascens HBUM200062 in VBNC state, and examines the effect on the cultivation of actinobacteria in soil. The results showed that the recombinant Rpf protein had resuscitation effect on M. luteus ACCC 41016T and R. marinonascens HBUM200062 in VBNC state. 83 strains of actinobacteria, which were distributed in 9 families and 12 genera, were isolated from the experimental group with recombinant Rpf protein in the culture medium. A total of 41 strains of bacteria, which were distributed in 8 families and 9 genera, were isolated from the control group without Rpf protein. The experimental group showed richer species diversity than the control group. Two rare actinobacteria, namely HBUM206391T and HBUM206404T, were obtained in the experimental group supplemented with Rpf protein. Both may be potential new species of Actinomadura and Actinokineospora, indicating that the recombinant expression of M. luteus ACCC 41016T Rpf protein can effectively promote the isolation and culture of actinobacteria in soil.

Gut microbiome heritability is nearly universal but environmentally contingent.

Relatives have more similar gut microbiomes than nonrelatives, but the degree to which this similarity results from shared genotypes versus shared environments has been controversial. Here, we leveraged 16,234 gut microbiome profiles, collected over 14 years from 585 wild baboons, to reveal that host genetic effects on the gut microbiome are nearly universal. Controlling for diet, age, and socioecological variation, 97% of microbiome phenotypes were significantly heritable, including several reported as heritable in humans. Heritability was typically low (mean = 0.068) but was systematically greater in the dry season, with low diet diversity, and in older hosts. We show that longitudinal profiles and large sample sizes are crucial to quantifying microbiome heritability, and indicate scope for selection on microbiome characteristics as a host phenotype.

Gut Microbiota Profile and Its Association with Clinical Variables and Dietary Intake in Overweight/Obese and Lean Subjects: A Cross-Sectional Study.

We aimed to differentiate gut microbiota composition of overweight/obese and lean subjects and to determine its association with clinical variables and dietary intake. A cross-sectional study was performed with 96 overweight/obese subjects and 32 lean subjects. Anthropometric parameters were positively associated with Collinsella aerofaciens, Dorea formicigenerans and Dorea longicatena, which had higher abundance the overweight/obese subjects. Moreover, different genera of Lachnospiraceae were negatively associated with body fat, LDL and total cholesterol. Saturated fatty acids (SFAs) were negatively associated with the genus Intestinimonas, a biomarker of the overweight/obese group, whereas SFAs were positively associated with Roseburia, a biomarker for the lean group. In conclusion, Dorea formicigenerans, Dorea longicatena and Collinsella aerofaciens could be considered obesity biomarkers, Lachnospiraceae is associated with lipid cardiovascular risk factors. SFAs exhibited opposite association profiles with butyrate-producing bacteria depending on the BMI. Thus, the relationship between diet and microbiota opens new tools for the management of obesity.

Macroparticle-enhanced cultivation of Lentzea aerocolonigenes: Variation of mechanical stress and combination with lecithin supplementation for a significantly increased rebeccamycin production.

The actinomycete Lentzea aerocolonigenes produces the antitumor antibiotic rebeccamycin. In previous studies the rebeccamycin production was significantly increased by the addition of glass beads during cultivation in different diameters between 0.5 and 2 mm and the induced mechanical stress by the glass beads was proposed to be responsible for the increased production. Thus, this study was conducted to be a systematic investigation of different parameters for macroparticle addition, such as bead diameter, concentration, and density (glass and ceramic) as well as shaking frequency, for a better understanding of the particle-induced stress on L. aerocolonigenes. The induced stress for optimal rebeccamycin production can be estimated by a combination of stress energy and stress frequency. In addition, the macroparticle-enhanced cultivation of L. aerocolonigenes was combined with soy lecithin addition to further increase the rebeccamycin concentration. With 100 g L-1 glass beads in a diameter of 969 µm and 5 g L-1 soy lecithin a concentration of 388 mg L-1 rebeccamycin was reached after 10 days of cultivation, which corresponds to the highest rebeccamycin concentrations achieved in shake flask cultivations of L. aerocolonigenes stated in literature so far.

A rapid and efficient method for the extraction and identification of menaquinones from Actinomycetes in wet biomass.

BACKGROUND: Menaquinones are constituents of prokaryote cell membranes where they play important functions during electron transport. Menaquinone profiles are strongly recommended for species classification when proposing a new Actinomycetes taxon. Presently, the most widely used methods to determine menaquinones are based on freeze-dried cells. Taxonomic research in our lab has revealed that menaquinone concentrations are low for some species of the genus Microbacterium, leading to difficulties in identifying menaquinones. RESULTS: Menaquinones extracted using the novel lysozyme-chloroform-methanol (LCM) method were comparable in quality to those obtained using the Collins method, the most widely used method. All tested strains extracted via the LCM method showed higher concentrations of menaquinones than those extracted via the Collins method. For some Microbacterium strains, the LCM method exhibited higher sensitivity than the Collins method, and more trace menaquinones were detected with the LCM method than the Collins method. In addition, LCM method is faster than the Collins method because it uses wet cells. CONCLUSION: The LCM method is a simple, rapid and efficient technique for the extraction and identification of menaquinones from Actinomycetes.

Streptacidiphilus fuscans sp. nov., a novel actinobacterium isolated from the root of pumpkin (Cucurbita moschata).

A novel acidophilic actinobacterium, designated strain NEAU-YB345T, was isolated from a pumpkin root collected from Mudanjiang, Heilongjiang Province, northeast PR China. Based on 16S rRNA gene sequence similarity and chemotaxonomic and morphological properties, the isolate was assigned to the genus Streptacidiphilus, with the high 16S rRNA gene sequence similarities to Streptacidiphilus melanogenes JCM 16224T (99.2 %), Streptacidiphilus anmyonensis JCM 16223T (99.1 %) and Streptacidiphilus jiangxiensis JCM 12277T (98.7 %). Its cell wall contained ll-diaminopimelic acid as the major diamino acid. Rhamnose, ribose, glucose and galactose were the detected sugars from the whole-cell hydrolysates. The phospholipid profile consisted of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, phosphatidylinositol mannoside and an unidentified phospholipid. The menaquinones were MK-9(H8) and MK-9(H6). Major fatty acids were C16 : 0, iso-C16 : 0, iso-C15 : 0 and anteiso-C15 : 0. Phylogenetic analysis using 16S rRNA gene and whole-genome sequences placed the strain in distinct clades but within the genus Streptacidiphilus. The DNA G+C content was 71.2 mol%. Based on DNA-DNA relatedness and physiological and biochemical data, the isolate could be distinguished from its closest relatives. Therefore, strain NEAU-YB345T represents a novel species of the genus Streptacidiphilus, for which the name Streptacidiphilus fuscans sp. nov. is proposed. The type strain is NEAU-YB345T (=CCTCC AA 2020030T=JCM 33976T).

Influence of genetic background and dietary oleic acid on gut microbiota composition in Duroc and Iberian pigs.

BACKGROUND: Phenotypic variability for productive and meat quality traits has been largely studied in Iberian pigs, especially in genetic selection and nutritional experiments. Complex interactions among genetic background, diet composition and gut microbiota hinder the correct assessment of each factor's contribution on phenotypes. In order to disentangle these interactions, we evaluated changes in gut microbiota composition comparing 48 Iberian and Duroc pigs fed diets with different energy source (standard diet with carbohydrates vs sunflower oil-enriched diet with high oleic acid content). RESULTS: A higher richness was observed for Iberian pigs (p < 0.05) and compositional analysis was applied for beta-diversity, differential abundance and pairwise log-ratio analyses. We found significant differences in overall microbiota composition between breeds, and also between diets inside breeds, to a lesser extent. Differential abundance analysis revealed that Duroc animals have more proportion of Actinobacteria and Prevotella, while Iberian replace those microorganisms with other more variable taxa. According to dietary differences, high-oleic fed animals were richer in Prevotella. We also found microbial ratios capable of separating animals by breeds and diets, mostly related to Actinobacteria. CONCLUSION: This study reveals that both genetic background and diet composition might have a relevant impact in gut microbiota composition. The application of compositional data analysis has facilitated the identification of microorganisms and ratios as possibly related to metabolic changes due to genetic background and, to a lower extent, to dietary changes. This may lead to a relevant progress in the knowledge of interactions between pig genetics, environment and gut microbiota.

Heat-inactivated Lactobacillus plantarum nF1 promotes intestinal health in Loperamide-induced constipation rats.

Constipation is a common condition that affects individuals of all ages, and prolonged constipation needs to be prevented to avoid potential complications and reduce the additional stress on individuals with pre-medical conditions. This study aimed to evaluate the effects of heat-inactivated Lactobacillus plantarum (HLp-nF1) on loperamide-induced constipation in rats. Constipation-induced male rats were treated orally with low to high doses of HLp-nF1 and an anti-constipation medication Dulcolax for five weeks. Study has 8 groups, control group; loperamide-treated group; Dulcolax-treated group; treatment with 3.2 × 1010, 8 × 1010 and 1.6 × 1011, cells/mL HLp-nF1; Loperamide + Dulcolax treated group. HLp-nF1 treated rats showed improvements in fecal pellet number, weight, water content, intestinal transit length, and contractility compared to the constipation-induced rats. Also, an increase in the intestine mucosal layer thickness and the number of mucin-producing crypt epithelial cells were observed in HLp-nF1-treated groups. Further, the levels of inflammatory cytokines levels were significantly downregulated by treatment with HLp-nF1 and Dulcolax. Notably, the metagenomics sequencing analysis demonstrated a similar genus pattern to the pre-preparation group and control with HLp-nF1 treatment. In conclusion, the administration of >3.2 × 1010 cells/mL HLp-nF1 has a positive impact on the constipated rats overall health.

One dog's waste is another dog's wealth: A pilot study of fecal microbiota transplantation in dogs with acute hemorrhagic diarrhea syndrome.

Canine acute hemorrhagic diarrhea syndrome (AHDS) has been associated in some studies with Clostridioides perfringens overgrowth and toxin-mediated necrosis of the intestinal mucosa. We aimed to determine the effect of a single fecal microbiota transplantation (FMT) on clinical scores and fecal microbiomes of 1 and 7 dogs with AHDS from New Zealand and South Africa. We hypothesized that FMT would improve AHDS clinical scores and increase microbiota alpha-diversity and short-chain fatty acid (SCFA)-producing microbial communities' abundances in dogs with AHDS after FMT. We sequenced the V3-V4 region of the 16S-rRNA gene in the feces of AHDS FMT-recipients and sham-treated control dogs, and their healthy donors at admission, discharge, and 30 days post-discharge. There were no significant differences in median AHDS clinical scores between FMT-recipients and sham-treated controls at admission or discharge (P = 0.22, P = 0.41). At admission, the Shannon diversity index (SDI) was lower in AHDS dogs than healthy donors (P = 0.002). The SDI did not change from admission to 30 days in sham-treated dogs yet increased in FMT-recipients from admission to discharge (P = 0.04) to levels not different than donors (P = 0.33) but significantly higher than sham-treated controls (P = 0.002). At 30 days, the SDI did not differ between FMT recipients, sham-treated controls, and donors (P = 0.88). Principal coordinate analysis of the Bray-Curtis index separated post-FMT and donor dogs from pre-FMT and sham-treated dogs (P = 0.009) because of increased SCFA-producing genera's abundances after FMT. A single co-abundance subnetwork contained many of the same OTUs found to be differentially abundant in FMT-recipients, and the abundance of this module was increased in FMT-recipients at discharge and 30 days, compared to sham-treated controls. We conclude in this small pilot study FMT did not have any clinical benefit. A single FMT procedure has the potential to increase bacterial communities of SCFA-producing genera important for intestinal health up to 30 days post-FMT.

Adaptive differentiation and rapid evolution of a soil bacterium along a climate gradient.

Microbial community responses to environmental change are largely associated with ecological processes; however, the potential for microbes to rapidly evolve and adapt remains relatively unexplored in natural environments. To assess how ecological and evolutionary processes simultaneously alter the genetic diversity of a microbiome, we conducted two concurrent experiments in the leaf litter layer of soil over 18 mo across a climate gradient in Southern California. In the first experiment, we reciprocally transplanted microbial communities from five sites to test whether ecological shifts in ecotypes of the abundant bacterium, Curtobacterium, corresponded to past adaptive differentiation. In the transplanted communities, ecotypes converged toward that of the native communities growing on a common litter substrate. Moreover, these shifts were correlated with community-weighted mean trait values of the Curtobacterium ecotypes, indicating that some of the trait variation among ecotypes could be explained by local adaptation to climate conditions. In the second experiment, we transplanted an isogenic Curtobacterium strain and tracked genomic mutations associated with the sites across the same climate gradient. Using a combination of genomic and metagenomic approaches, we identified a variety of nonrandom, parallel mutations associated with transplantation, including mutations in genes related to nutrient acquisition, stress response, and exopolysaccharide production. Together, the field experiments demonstrate how both demographic shifts of previously adapted ecotypes and contemporary evolution can alter the diversity of a soil microbiome on the same timescale.

An Alternative and Conserved Cell Wall Enzyme That Can Substitute for the Lipid II Synthase MurG.

The cell wall is a stress-bearing structure and a unifying trait in bacteria. Without exception, synthesis of the cell wall involves formation of the precursor molecule lipid II by the activity of the essential biosynthetic enzyme MurG, which is encoded in the division and cell wall synthesis (dcw) gene cluster. Here, we present the discovery of a cell wall enzyme that can substitute for MurG. A mutant of Kitasatospora viridifaciens lacking a significant part of the dcw cluster, including murG, surprisingly produced lipid II and wild-type peptidoglycan. Genomic analysis identified a distant murG homologue, which encodes a putative enzyme that shares only around 31% amino acid sequence identity with MurG. We show that this enzyme can replace the canonical MurG, and we therefore designated it MglA. Orthologues of mglA are present in 38% of all genomes of Kitasatospora and members of the sister genus Streptomyces CRISPR interference experiments showed that K. viridifaciens mglA can also functionally replace murG in Streptomyces coelicolor, thus validating its bioactivity and demonstrating that it is active in multiple genera. All together, these results identify MglA as a bona fide lipid II synthase, thus demonstrating plasticity in cell wall synthesis.IMPORTANCE Almost all bacteria are surrounded by a cell wall, which protects cells from environmental harm. Formation of the cell wall requires the precursor molecule lipid II, which in bacteria is universally synthesized by the conserved and essential lipid II synthase MurG. We here exploit the unique ability of an actinobacterial strain capable of growing with or without its cell wall to discover an alternative lipid II synthase, MglA. Although this enzyme bears only weak sequence similarity to MurG, it can functionally replace MurG and can even do so in organisms that naturally have only a canonical MurG. The observation that MglA proteins are found in many actinobacteria highlights the plasticity in cell wall synthesis in these bacteria and demonstrates that important new cell wall biosynthetic enzymes remain to be discovered.

Improved AP-3 production through combined ARTP mutagenesis, fermentation optimization, and subsequent genome shuffling.

Ansamitocin (AP-3) is an ansamycins antibiotic isolated from Actinosynnema pretiosum and demonstrating high anti-tumor activity. To improve AP-3 production, the A. pretiosum ATCC 31565 strain was treated with atmospheric and room temperature plasma (ARTP). Four stable mutants were obtained by ARTP, of which the A. pretiosum L-40 mutant produced 242.9 mg/L AP-3, representing a 22.5% increase compared to the original wild type strain. With seed medium optimization, AP-3 production of mutant L-40 reached 307.8 mg/L; qRT-PCR analysis revealed that AP-3 biosynthesis-related gene expression was significantly up-regulated under optimized conditions. To further improve the AP-3 production, genome shuffling (GS) technology was used on the four A. pretiosum mutants by ARTP. After three rounds of GS combined with high-throughput screening, the genetically stable recombinant strain G3-96 was obtained. The production of AP-3 in the G3-96 strain was 410.1 mg/L in shake flask cultures, which was 44.5% higher than the L-40 production from the parental strain, and AP-3 was increased by 93.8% compared to the wild-type A. pretiosum. These results suggest that the combination of mutagenesis, seed medium optimization, and GS technology can effectively improve the AP-3 production capacity of A. pretiosum and provide an enabling methodology for AP-3 industrial production.

Fusobacterium nucleatum impedes remission of colitis in a mouse model.

The role of Fusobacterium nucleatum, often associated with intestinal diseases, in the remission of dextran sulfate sodium (DSS)-induced colitis was investigated. Female mice were divided into groups DC (DSS control) and DF (DSS + F. nucleatum). F. nucleatum (1.0 × 1010 cfu/mouse/day) in phosphate-buffered saline (PBS) was orally given to DF, while DC had PBS only. All mice had DSS in drinking water. In Experiment 1, mice underwent 2 inflammation phases, an in-between recovery phase and had their disease activity indices (DAI) calculated. Experiment 2 was similarly conducted, except that mice were dissected 3 days postrecovery, and had blood and colonic mucosal samples collected. In Experiment 1, DF had significantly (P < .05) higher DAI than DC, during the recovery and 2nd inflammation phases. In Experiment 2, genus Bacteroides was significantly (P < .05) higher and family Lachnospiraceae significantly lower in cecal mucosa-associated microbiota of DF than in that of DC. We concluded that F. nucleatum can impede colitis remission.

The rhizosphere microbiome plays a role in the resistance to soil-borne pathogens and nutrient uptake of strawberry cultivars under field conditions.

Microbial-root associations are important to help plants cope with abiotic and biotic stressors. Managing these interactions offers an opportunity for improving the efficiency and sustainability of agricultural production. By characterizing the bacterial and archaeal community (via 16S rRNA sequencing) associated with bulk and rhizosphere soil of sixteen strawberry cultivars in two controlled field studies, we explored the relationships between the soil microbiome and plant resistance to two soil-borne fungal pathogens (Verticillium dahliae and Macrophomina phaseolina). Overall, the plants had a distinctive and genotype-dependent rhizosphere microbiome with higher abundances of known beneficial bacteria such as Pseudomonads and Rhizobium. The rhizosphere microbiome played a significant role in the resistance to the two soil-borne pathogens as shown by the differences in microbiome between high and low resistance cultivars. Resistant cultivars were characterized by higher abundances of known biocontrol microorganisms including actinobacteria (Arthrobacter, Nocardioides and Gaiella) and unclassified acidobacteria (Gp6, Gp16 and Gp4), in both pathogen trials. Additionally, cultivars that were resistant to V. dahliae had higher rhizosphere abundances of Burkholderia and cultivars resistant to M. phaseolina had higher abundances of Pseudomonas. The mechanisms involved in these beneficial plant-microbial interactions and their plasticity in different environments should be studied further for the design of low-input disease management strategies.

Role of Williamsia and Segniliparus in human infections with the approach taxonomy, cultivation, and identification methods.

The genera Williamsia and Segniliparus are of aerobic actinomycetes and at the time of writing, they have 12 and 2 species, respectively. These genera cause various infections in humans. In this review, we surveyed their taxonomy, isolation, identification, as well as their role to cause human infections.

Improving Biotransformation Efficiency of Arthrobacter simplex by Enhancement of Cell Stress Tolerance and Enzyme Activity.

Arthrobacter simplex exhibits excellent Δ1-dehydrogenation ability, but the acquisition of the desirable strain is limited due to lacking of comprehensive genetic manipulation. Herein, a promoter collection for fine-tuning gene expression was achieved. Next, the expression level was enhanced and directed evolution of the global transcriptional factor (IrrE) was applied to enhance cell viability in systems containing more substrate and ethanol, thus contributing to higher production. IrrE promotes a stronger antioxidant defense system, more energy generation, and changed signal transduction. Using a stronger promoter, the enzyme activities were boosted but their positive effects on biotransformation performance were inferior to cell stress tolerance when exposed to challenging systems. Finally, an optimal strain was created by collectively reinforcing cell stress tolerance and catalytic enzyme activity, achieving a yield 261.8% higher relative to the initial situation. Our study provided effective methods for steroid-transforming strains with high efficiency.

Urolithins in Human Breast Milk after Walnut Intake and Kinetics of Gordonibacter Colonization in Newly Born: The Role of Mothers' Urolithin Metabotypes.

The maternal-infant transmission of several urolithins through breast milk and the gut colonization of infants by the urolithin-producing bacterium Gordonibacter during their first year of life were explored. Two trials (proof-of-concept study: n = 11; validation study: n = 30) were conducted, where breastfeeding mothers consumed walnuts as a dietary source of urolithin precursors. An analytical method was developed and validated to characterize the urolithin profile in breast milk. Total urolithins ranged from 8.5 to 176.9 nM, while they were not detected in breast milk of three mothers. The mothers' urolithin metabotypes governed the urolithin profile in breast milk, which might have biological significance on infants. A specific quantitative polymerase chain reaction method allowed monitoring the gut colonization of infants by Gordonibacter during their first year of life, and neither breastfeeding nor vaginal delivery was essential for this. The pattern of Gordonibacter establishment in babies was conditioned by their mother's urolithin metabotype, probably because of mother-baby close contact.