This study aimed to investigate the impact of probiotic-enhanced children's formula milk on oral health and the oral microbiome in preschool children. A randomized controlled trial was conducted with 163 preschool children, including 93 in the intervention group and 70 in the control group. The intervention group consumed formula milk containing Bifidobacterium animalis subsp. lactis Probio-M8, while the control group continued consuming regular student milk. The intervention lasted for 2 months. Saliva samples were collected at baseline, 2 weeks, and 2 months. The 2bRAD-M simplified metagenomics technique was used to identify the composition and functional pathways of the oral microbiota. The results indicated that the intervention significantly improved the oral hygiene status of children in the intervention group after health assessments. The proportion of children with “good” oral hygiene significantly increased from 20 cases at baseline to 27 cases over 2 weeks (P<0.05) and then remained elevated (22 cases) over 2 months. Moreover, the number of erupted teeth continued to increase over the observation period (P<0.05), while the incidence of tooth decay remained stable. Therefore, the dental caries was reduced after the probiotic intervention. Microbiome diversity analysis revealed that there was significant structural reshaping. The intervention group exhibited significantly lower α-diversity (Shannon and Simpson indices) over 2 months, compared with the control group (P = 0.001). β-diversity analysis (PCoA using Bray-Curtis distance) with PERMANOVA tests indicated that the intervention and time factors were attributed to the microbial community structure (P=0.001). Notably, there was a more pronounced effect on functional structure, rather than on taxonomic composition, with higher PERMANOVA F-values for the functional profiles. In terms of oral microbiota composition, the intervention group exhibited a significant increase in the relative abundance of Veillonella species, including Veillonella nakazawae and Veillonella rogosae, after 2 weeks and 2 months of intervention. This enrichment remained significantly higher than that of the control group at both time points (P < 0.05). Conversely, the relative abundance of certain Streptococcus species, such as Streptococcus infantis and Streptococcus oralis S, was lower (P < 0.001) than that in the control group over 2 weeks. Streptococcus species, including Streptococcus parasanguinis and Streptococcus symci, showed a slight rebound in relative abundance within the intervention group after 2 months, which remained lower than the levels in the control group at the same time point. Functional analysis of the oral microbiota revealed that the probiotic intervention also modulated multiple metabolic pathways in a time-dependent manner. The intervention group exhibited enrichment in the pathways with iron acquisition (K02014, iron complex outer membrane receptor protein), oxidative stress response (K03711, fur family transcriptional regulator), and substance transport (K03561, biopolymer transport protein ExbB) after 2 weeks post-intervention. Concurrently, the intervention group shared the lower relative abundance of genes encoding amino acid transport systems (K02028-K02030) and ABC transporter-related functions (K01990, K01992), compared with the control group. While K02517 (Kdo2-lipid IVA lauroyltransferase/acyltransferase) remained elevated in the intervention group by the 2-month endpoint. The amino acid and ABC transporters shared the attenuated differences or returned toward control levels. Differentially expressed pathways reflected the dynamic functional adaptation and stabilization of the microbial community. Correlation analysis further revealed that the abundance of Veillonella species, such as Veillonella sp900549845, Veillonella nakazawae, and Veillonella parvula A, was significantly positively correlated with oral hygiene status (r>0), while some Streptococcus species and specific metabolic pathways, such as K07024 (sucrose-6-phosphatase) and K06147 (ATP-binding cassette, subfamily B), were positively correlated with the risk of tooth decay (r>0). In conclusion, the probiotic-enhanced children's formula milk significantly improved preschool children's oral health, particularly in terms of oral hygiene and tooth development, and potentially delayed tooth decay. The intervention also demonstrated a modulating effect on the composition and functionality of the oral microbiota. The microbial diversity can further support the potential of probiotics in oral health. Future studies should explore the long-term probiotic intervention on tooth decay prevention and the stability of the oral microbiota.

Sedentary behavior is associated with gut microbiota dysbiosis and increased metabolic risk, yet effective microbiome-modulating strategies for individuals who cannot engage in sufficient physical activity remain underexplored. Probiotics may modulate sedentary-associated microbial alterations. We conducted a cross-sectional multi-omics comparison of physically active (PA, n = 65) and physically inactive (PI, n = 90) young adults, followed by a 6-week randomized, double-blind, placebo-controlled trial in the PI cohort (probiotic: PIP, n = 45; placebo: PIC, n = 45). At baseline, PA individuals exhibited higher α-diversity and a more favorable microbial community structure than PI participants, enriched in Bifidobacterium adolescentis, B. bifidum, Anaerostipes hadrus, and associated metabolites. A random forest classifier distinguished PA from PI with high accuracy (96.1%; area under the curve, AUC = 0.993). Following intervention, PIP subjects showed a modest shift toward an active-like microbiome: root Jensen-Shannon similarity between PIP and PA (69.3%) was significantly higher than between PIC and PA (67.8%; P < 0.001), and levels of key taxa (A. hadrus, B. bifidum) and metabolites (vanillic acid, prolylglycine) moved closer to PA. Consistently, classifier performance decreased for PIP vs. PA (AUC 0.690; accuracy 68.2%) but remained higher for PIC vs. PA (AUC 0.843; accuracy 80.0%), indicating a probiotic-associated reduction in microbiome dissimilarity. These findings suggest that probiotic supplementation induces a partial, ecologically measurable shift toward an active-like gut microbiome configuration in inactive individuals, without replicating the full physiological benefits of regular physical activity, highlighting its potential as a scalable, adjunctive strategy for microbiome health in sedentary populations.

Lacticaseibacillus paracasei Zhang is an excellent strain with probiotic properties such as immunomodulatory and antioxidant activities. DNA methylation is an important epigenetic mechanism that plays a key role in many physiological processes in bacteria. In order to better utilize the strain, this study focused on the effect of methylation on the storage properties of two starter cultures of L. paracasei Zhang and its DNA methylation mutant (ΔpglX) at 30 ℃. The results showed that after 90 d of storage, the viable number of the mutant significantly increased compared with the wild type (P < 0.01). Using untargeted metabolomics, 269 differential metabolites were observed in the mutant compared with the wild type, which were mainly enriched in the nucleotide metabolism, purine metabolism, pyrimidine metabolism, citrate cycle, glyoxylate, and dicarboxylate metabolism pathways in the negative ion mode. In the positive ion mode, they were mainly enriched in the biotin metabolism pathway. These findings confirmed that DNA methylation could improve the storage properties of L. paracasei Zhang through the generation and utilization of carbohydrates and fatty acids.

The aim of this study was to investigate the metabolite changes in Lacticaseibacillus paracasei Zhang ΔpglX, a DNA methyltransferase mutant, after successive passages and to explore the possible mechanism of metabolic regulation during the passage process. We monitored the morphological characteristics and changes in the carbohydrate-metabolizing capacity of this strain. The metabolites at different passages were characterized using ultra-high performance liquid chromatography-mass spectrometry (UPLC-MS) combined with principal component analysis (PCA) and orthogonal partial least squares-discriminant analysis (OPLS-DA). The identification of significantly differential metabolites and the key metabolic pathways involving them was performed through Kyoto Encyclopedia of Genes and Genomes (KEGG) database annotation. The phenotype of L. paracasei Zhang ΔpglX exhibited stable inheritance during successive passages, but the metabolic profile changed with increasing passage. The differential metabolites were mainly enriched in organic heterocyclic compounds, nucleosides, nucleotides and their analogs, lipids and lipid-like molecules, and the nucleotide metabolic pathway was the most dominant enriched pathway, which agreed with the results of differential metabolite enrichment analysis. These results suggested that L. paracasei Zhang ΔpglX could adapt to environmental changes by adjusting metabolic pathways, providing new insights into metabolic pathway changes in Lactobacillus during adaptive evolution.

This study reviewed clinical evidence of probiotics-mediated effects on constipation. Four databases were used in the literature searches, namely Cochrane Library, Embase, Pubmed, and Web of Science. The last retrieval time was March 2021. Collected data were analyzed by Review Manager (version 5.3) and Stata (version 14). The primary search retrieved 8418 articles after removing duplicates. Eventually, 26 studies were included in the meta-analysis. Administration of probiotics significantly increased stool frequency (MD: 1.15 times/week; 95% CI: 0.59 to 1.70; P < 0.0001), improved bloating (MD: –0.48; 95% CI: –0.89 to –0.07; P = 0.02), reduced abdominal pain (MD: –0.71; 95% CI: –1.25 to –0.16; P = 0.01), and improved quality of life (MD: –0.73; 95% CI: –1.37 to –0.10; P = 0.02). However, the clinical effect of intake of probiotics on stool consistency was non-significant (MD: 0.07; 95% CI: –0.34 to 0.48; P = 0.73). Based on our analysis, probiotic supplements were effective in relieving constipation through symptom improvement. The effectiveness of dosage forms of intervention ranked: capsules > others (tablets, powder) > fermented milk.