Background/Objectives: Individuals with childhood obesity exhibit significant metabolic heterogeneity, necessitating precise biomarkers for risk stratification and assessment. This multi-omics investigation characterizes metabolic and microbial signatures underlying divergent metabolic phenotypes in the context of pediatric obesity. Methods: We analyzed 285 Chinese children (5–7 years) stratified into five groups: wasting (WAS, n = 55), metabolically healthy/unhealthy and normal weight (MHWH, n = 54; MUWH, n = 67), and metabolically healthy/unhealthy obesity (MHO, n = 36; MUO, n = 73). Untargeted metabolomics (Orbitrap ID-X Tribrid™) and 16S rRNA sequencing were integrated with multivariate analyses (OPLS-DA with VIP > 1, FDR < 0.05; Maaslin 2 with TSS normalization and BH correction, FDR < 0.10). Results: Analysis identified 225 differential metabolites and 12 bacterial genera. The proportion of steroids and their derivatives among differential metabolites in the MUO/MHO group was significantly lower than that in the OVOB/NOR and OVOB/WAS groups (2.12% vs. 7.9–14.1%). MUO displayed elevated C17 sphinganine and LysoPC (O-18:0) levels but reduced PI (16:0/14:1) levels. In contrast, OVOB showed upregulated glycerol phospholipids (LPCs and PSs) and downregulated PE species (e.g., PE(16:0/16:0)) as well as gut microbiota dysbiosis characterized by a higher Firmicutes/Bacteroidetes (F/B) ratio (2.07 vs. 1.24 in controls, p = 0.009) and reduced α diversity (Ace index, Chao1 index, and Shannon index values were lower in the OVOB group, Shannon index: 2.96 vs. 3.45, p = 0.03). SCFA-producing genera were negatively correlated with the OVOB group, while positively associated with PE(16:0/16:0). Internal validation showed differential metabolites had potential predictive efficacy for MUO/MHO (AUC = 0.967) and OVOB/NOR (AUC = 0.888). Conclusions: We identified distinct lipid disruptions characterizing obesity subtypes, including steroid/terpene deficits and sphingolipid/ether lipid dysregulation in the MUO/MHO groups as well as phospholipid imbalance (↑LPC/PS↓PE) in the OVOB/NOR groups. The gut microbiota exhibited a profile characterized by low diversity, an increased F/B ratio, and a reduced abundance of SCFA-producing genera. These findings suggest potential biomarkers for childhood obesity stratification, though further validation is warranted.

Purpose We aimed to investigate the effect of tatABC gene deletion on the pathogenicity of enterotoxigenic Escherichia Coli (ETEC). Methods Changes in bacterial dynamics and virulence after deletion were examined using mobility and animal toxicity tests for ETEC. Further, differential expression of proteins between the gene-deletion and wild-type strains was analyzed using two-dimensional gel electrophoresis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry to explore the possible mechanisms underlying the effects of this gene on bacterial virulence. Result After tatABC knockout, the virulence of ETEC H10407 was strongly attenuated, and its invasion in rabbit intestinal mucosa was significantly reduced. Mass spectrometry revealed that 10 differentially expressed proteins involved in physiological functions of bacteria, which may be associated with changes in bacterial motility and pathogenicity. Conclusion The research shows that the twin-arginine translocation system of ETEC may be closely related to its virulence.

Background We aimed to investigate the effect of Tat deletion on the pathogenicity of enterotoxigenic Escherichia coli (ETEC). Changes in bacterial dynamics and virulence after deletion were examined using mobility and animal toxicity tests for ETEC. Further, differential expression of proteins between the gene-deletion and wild-type strains was analyzed using two-dimensional gel electrophoresis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry to explore the possible mechanisms underlying the effects of this gene on bacterial virulence. Results After Tat knockout, the virulence of ETEC10407 was strongly attenuated, and its invasion in rabbit intestinal mucosa was significantly reduced. Mass spectrometry revealed that 17 differentially expressed proteins involved in physiological functions of bacteria, such as virulence and substance or energy metabolism might affect bacterial pathogenicity. Conclusions The Tat protein transport system of ETEC is closely related to its virulence.