Lianzhong Ai

Bacteroides uniformis is a promising candidate for targeted modulation of the gut microbiota. However, the functions of its genes remain to be elucidated. Electroporation-based genetic manipulation systems are powerful tools for studying gene function; However, the low efficiency of electroporation-mediated transformation of Bacteroides with plasmids isolated from Escherichia coli limits their application. In this study, we improved the transformation efficiency of B. uniformis BNCC368209 with E. coli-derived plasmids by optimizing electroporation conditions and knocking down selected genes. Under optimized electroporation conditions, transformation efficiency with E. coli-derived plasmids reached 2.35 × 10⁴ CFU/μg DNA. Under the same optimized conditions, transformation efficiency with Bacteroides-derived plasmids reached 3.25 × 10⁶ CFU/μg DNA. RNA sequencing (RNA-seq) was used to compare post-selection transformants obtained with B. uniformis-derived and E. coli-derived plasmids as a hypothesis-generating screen. Of the 905 differentially expressed genes, nine candidates were prioritized for subsequent CRISPRi testing based on functional annotation and RT-qPCR screening. CRISPR interference (CRISPRi) using catalytically inactive Cas9 (dCas9) was used to generate strains with targeted knockdown of these genes. Knockdown of gene0629 (mraY) and gene0737 (hupB) increased transformation efficiency with E. coli-derived plasmids to 21.9 and 41.9 times that of the control strain without gene knockdown, respectively. Phenotypic analyses suggested altered cell envelope integrity following mraY knockdown and showed increased pB006 retention following hupB knockdown. These phenotypes may be associated with improved transformation efficiency, although causal relationships remain to be established. Together, these findings provide a strategy for improving transformation efficiency in B. uniformis and may inform the development of genetic manipulation systems for other Bacteroides species.

Faecalibacterium prausnitzii (Fp), a potential candidate for a next-generation, is widely distributed in the feces and intestinal tract of mammals. Accumulating evidence indicates that Fp and its metabolites exert anti-inflammatory, immunomodulatory, and maintain intestinal barrier integrity. In this review, we summarize the biological characteristics of Fp and its nutritional cross feeding interactions with other microbial species. We further synthesize current evidence on the local roles of Fp in intestinal diseases and systemic effects on distant organs via the gut-organ axis. Furthermore, we outline the mechanisms by which its effector molecules, including butyrate, microbial anti-inflammatory molecule (MAM), and extracellular vesicles (EVs), contribute to disease amelioration. Finally, we discuss the current challenges and future perspectives for Fp. Collectively, as an important commensal bacterium in the gut, Fp provides a theoretical basis for the development of novel functional microorganisms with probiotic properties.

Phyllanthus emblica Linn. contains abundant free phenolic (PEFP) and bound phenolic (PEBP), both of which have demonstrated potential antidiabetic activities.

This study investigated the protective effects and underlying mechanisms of milk proteins on Goji Berry polyphenols (GBP). An in vitro digestion experiment validated that milk proteins (whey protein [WP] and casein [CA]) significantly enhanced the retention rate of GBP during the digestion process, with CA showing a more pronounced protective effect. To elucidate the mechanisms, β‐casein (βCN) and β‐lactoglobulin (βLG) were employed as representative models for CA and WP, respectively. Both proteins formed complexes with predominant GBP (rutin and p ‐coumaric acid [PCA]) through static quenching driven by hydrogen bonding and hydrophobic interactions. βCN exhibited higher K _a values (40.41 and 15.89 × 10 ⁴ M ⁻¹ ) for rutin (Ru) and PCA than βLG (35.93 and 3.92 × 10 ⁴ M ⁻¹ ). Notably, a comparative analysis of dynamic light scattering (DLS) and low‐field nuclear magnetic resonance (Lf‐NMR) revealed distinct protective mechanisms: βLG formed loose aggregates with significantly increased particle size but retained high water mobility, whereas βCN formed a more compact micellar structure and significantly restricted water mobility. Molecular docking demonstrated that βCN provides a more robust structural barrier for Ru and PCA by encapsulating them within internal cavity. In contrast, βLG primarily binds polyphenols on its surface or hydrophobic pocket, thus showing a weaker protective property than βCN. Therefore, the excellent binding affinity and enclosed encapsulation mode of βCN may explain why CA exhibits a superior protective effect on GBP compared to WP. Practical Applications: This study elucidates the protective mechanism of milk proteins on GBP, laying a theoretical and experimental foundation for the development of high‐value dairy products rich in GBP.

Immunoglobulins exhibit important biological functions, including the neutralization of cytotoxins, enhancement of phagocytic activity, and activation of the complement system, which have driven their widespread application in both the food and pharmaceutical industries. Due to their low cost and short production cycles, microbial expression systems such as bacteria and yeast have been increasingly developed in recent years for immunoglobulin production. However, microbial systems face considerable challenges in ensuring proper protein folding, accurate chain assembly, and the soluble expression of full-length immunoglobulins. Recent optimization strategies have focused on host engineering (e.g., modulating secretion pathways and chaperone proteins), the coordinated regulation of expression elements (e.g., optimizing the light-to-heavy chain ratio), and regulation of fermentation processes. In addition to summarizing the above strategies, this review discusses the progress made in expressing both full-length immunoglobulins and antibody fragments across different microbial hosts, analyzes the advantages and limitations of each system, and explores potential future directions, aiming to provide a reference for the efficient heterologous expression of immunoglobulins.

BACKGROUND: Ice recrystallization is a key factor limiting the storage stability of ice cream. Although tamarind seed polysaccharide (TSP) is recognized for its thickening and ice recrystallization inhibition (IRI) capabilities, its specific mechanism of action in frozen dairy systems remains underexplored. This study aimed to elucidate the stabilizing mechanism of TSP (0%, 0.2%, and 0.5% w/w ) in ice cream formulations. RESULTS: Rheological analysis revealed that TSP significantly modified the flow properties of the mixes. The consistency coefficient ( K ) increased from 0.4451 to 1.1593 Pa·s ⁿ , and the flow behavior index ( n ) increased from 0.2876 to 0.6445, confirming the characteristic shear‐thinning behavior of the mixes. Oscillatory tests confirmed the formation of a weak gel‐like network (storage modulus ( G' ) > loss modulus ( G″ )), imparting viscoelastic stability to the mix. At the microstructural level, TSP promoted the formation of a finer, more monodisperse emulsion and effectively inhibited Ostwald ripening, reducing the mean ice crystal area from 221.69 μm ² to 135.78 μm ² . Furthermore, TSP retarded crystallization kinetics and reduced freezable water content, leading to a prolonged phase transition. These microstructural changes translated to enhanced cohesiveness (rising from 5.835 to 7.121) and substantially reduced hardness in the final product, although this was accompanied by an increase in the melting rate. CONCLUSION: These findings demonstrate that TSP is a potent cryostabilizer that optimizes the microstructural integrity and textural quality of ice cream. This research provides a robust theoretical foundation for utilizing TSP as a functional ingredient in the frozen dessert industry. © 2026 Society of Chemical Industry.

Polysaccharides in traditional Chinese medicine (TCM) are essential compounds responsible for therapeutic effects, exhibiting immunomodulatory, anti‐inflammatory, and antioxidant properties. However, their high molecular weight, low solubility, and poor bioavailability restrict clinical application. Degrading these into smaller, absorbable TCM oligosaccharides (TCMOs) not only overcomes these barriers but may also enhance biological activity, offering a new avenue for high‐value TCM development. This review summarizes the progress in preparing TCMOs using chemical, physical, and enzymatic methods. It outlines techniques for the separation, purification, and structural characterization of degradation products, while examining the biological activities of TCMOs in regulating gut microbiota and enhancing immunity. Enzymatic hydrolysis is established as a superior strategy for precision degradation due to its specificity and tunable kinetics. Leveraging gut microbiota‐derived Polysaccharide Utilization Loci (PULs) for “bio‐intelligent” preparation represents a transformative frontier for generating structurally defined TCMOs. For isolation, chromatographic platforms remain the most versatile methodologies. While the immunomodulatory effects of TCMOs are well‐documented, a critical gap remains concerning structure–activity relationships in antitumor pathways and metabolic absorption. By synthesizing these insights, this review facilitates the precision customization and industrial advancement of bioactive TCMOs.

Food-grade microorganisms utilize core cofactors, such as nicotinamide adenine dinucleotide (NAD) and its phosphate form (NADP), to mediate redox reactions and regulate energy metabolism homeostasis as well as biosynthesis of functional components. In metabolic engineering, perturbation of the NAD(P)⁺/NAD(P)H network may significantly disrupt intracellular redox homeostasis, leading to impaired strain growth and limited synthesis of targeted functional products. This review systematically examines the latest research progress in the field of food-grade microbial cofactor engineering, focusing on the key mechanisms and synergistic pathways of core strategies, such as metabolic flux optimization and cofactor regeneration systems, in maintaining cellular redox homeostasis and enhancing the biosynthesis of functional ingredients. Future research should focus on exploring the potential for integrating multi-omics approaches and intelligent control technologies, proposing innovative approaches to address the challenges of industrialized production, and providing theoretical support for food biomanufacturing.

BACKGROUND: Streptococcus thermophilus S‐3 is an industrial dairy fermentation species, which can modulate growth and metabolism through quorum sensing (QS). However, the regulatory mechanisms governing high‐density bacterial proliferation remain elusive in S. thermophilus S‐3. This study focuses on Rgg, a quorum sensing‐associated transcription factor, examining its regulatory role in high‐density growth dynamics. RESULTS: Three Rgg putative transcriptional regulators ( orf383 , orf447 , and orf1010 ) in S. thermophilus S‐3 were identified, and their evolutionary conservation and conserved DNA‐binding domains were characterized, supporting their predicted role in transcriptional regulation of high‐density growth. Phenotypic analysis showed that the S‐3Δ447 mutant exhibited 30.9% lower maximum optical density and 68.8% lower viability than wild‐type strains. Transcriptomic profiling revealed Rgg‐dependent dysregulation: 209 upregulated/272 downregulated genes at 7 h, 82 downregulated/20 upregulated at 12 h, and 25 upregulated/33 downregulated at 20 h. KEGG pathway analysis highlighted enrichment in ABC transporters and amino/nucleotide sugar metabolic. Notably, oppC / oppD downregulation disrupted SHP‐Rgg binding, impairing oligopeptide signaling. Furthermore, ganP / ganQ suppression reduced lactose uptake capacity and ultimately suppressed cellular proliferation. Conversely, artP upregulation promoted arginine catabolism preference, effectively compensating for observed growth deficiencies. CONCLUSION: This study elucidated the regulatory role of rgg genes in the high‐cell‐density growth of S. thermophilus S‐3. Rgg coordinates high‐density cell proliferation through the dual regulation of peptide‐mediated QS initiation and carbon–nitrogen metabolic flux reprogramming. © 2026 Society of Chemical Industry.