The application of bifidobacteria in fermented dairy products is often limited by insufficient storage stability and unclear mechanistic links between microbial metabolism and host benefits. Here, we investigated the technological performance, aroma homeostasis, and constipation-alleviating mechanism of Bifidobacterium animalis J12 co-fermented yogurt (J12-Y). J12 co-fermentation maintained excellent physicochemical stability during 28 days of refrigeration, with viable counts remaining above 7.0 log CFU/mL and preserving the classical buttery-creamy aroma backbone, as evidenced by stable 2,3-butanedione (OAV ≈ 41-42). In a loperamide-induced constipation mouse model, J12-Y improved bowel function by shortening the time to first black stool (approximately 110 vs. 131 min), increasing fecal water content (approximately 56% vs. 28%), and enhancing intestinal transport rate (approximately 67% vs. 45%) relative to the model group. Mechanistically, J12-Y was associated with a coordinated cascade of metabolic and neuroendocrine events. Fecal metabolomics revealed robust enrichment of short-chain fatty acids (SCFAs), particularly acetate, propionate, and butyrate, alongside modulation of indole derivatives and bile acid-related metabolites. These metabolic shifts were accompanied by a pro-motility neuroendocrine profile, characterized by elevated excitatory neurotransmitters and hormones (5-HT, ACh, SP, GAS, MTL) and reduced inhibitory signaling (SS, VIP). Spearman correlation analysis further revealed critical functional links: butyric acid showed strong positive correlations with 5-HT (r = 0.62) and intestinal transport rate (r = 0.80); acetic acid was positively correlated with fecal water content (r = 0.67); and deoxycholic acid exhibited negative correlations with intestinal transport rate (r = -0.82) and 5-HT (r = -0.74). Collectively, these findings support a proposed "metabolite-nerve-endocrine" framework in which J12-Y mediates relief of constipation through integrated microbial metabolic and neuroendocrine modulation. Overall, B. animalis J12 represents a promising adjunct culture that couples aroma stability with constipation-relieving potential through integrated microbial metabolic and neuroendocrine modulation.

The post-acidification of fermented milk is primarily caused by the sustained acid production of Lactobacillus delbrueckii subsp. bulgaricus during storage at ambient temperature, which significantly compromises product quality. Results from growth curves, acid production assays, and multiple microscopy techniques (laser scanning confocal microscopy, scanning electron microscopy, and transmission electron microscopy) collectively demonstrate that 256 AU/mL plantaricin BM-1 alters the morphology and cell membrane permeability of L. bulgaricus YR, reducing its acid production capacity while preserving its viability. Transcriptomic analysis revealed that this treatment significantly upregulated fatty acid metabolism and the gene LDB_RS05285, and downregulated atpE in L. bulgaricus YR. Metabolomics further revealed significant alterations in membrane-associated fatty acids and sterol lipids, corroborating BM-1's influence on cell membrane structure. Integrating observational, transcriptomic, and metabolomic data, it is concluded that 256 AU/mL plantaricin regulates post-fermentation acidification by modulating membrane permeability and structure, thereby controlling the expression of marker genes LDB_RS05285 and atpE. Storage experiments demonstrate that BM-1 addition maintains yoghurt pH ≥ 3.9 for 21 days at ambient temperature, effectively retarding post-acidification.

This study investigated the effects of 2 Lactobacillus paracasei strains, KL1 and BK56, on the physicochemical properties, microstructure, texture characteristics, and sensory quality of a compound fermented yogurt system (GK107: L. paracasei KL1, Leuconostoc mesenteroides G12S, Chr. Hansen Commercial Starter Culture; G56107: L. paracasei BK56, L. mesenteroides G12S, Chr. Hansen Commercial Starter Culture), and further integrated genomic and metabolomic analyses to infer their shelf-life and optimal consumption period. The results showed that GK107 yogurt maintained stable quality throughout the 28-d storage period (at d 28: pH 4.07; titratable acidity 93.25 °T; exopolysaccharide content 0.31 g/L; water-holding capacity 53.05%; sensory score 83), and rapidly formed a stable gel structure that persisted for an extended duration. In contrast, the quality of G56107 yogurt deteriorated during the later stage of storage (at d 28: pH 4.0; titratable acidity 98.4 °T; exopolysaccharide content 0.31 g/L; water-holding capacity 51.3%; sensory score 67). Genomic analysis revealed that, compared with the L. paracasei KL1 strain, the L. paracasei BK56 strain carried loss-of-function mutations in multiple key genes associated with flavor synthesis, polysaccharide metabolism, and proteolysis, including alsS, prtP, glpO, AWC33_RS01450, AWC33_RS00855, AWC33_RS01070, and AWC33_RS01805. These mutations may have played a role in the gradual flavor deterioration, and weak post-acidification control observed in G56107 yogurt during prolonged storage. Based on the above results, it is reasonable to suggest that GK107 yogurt is suitable for long-term storage with an optimal consumption period of 14 to 28 d, whereas G56107 yogurt is more suitable for short-term storage and recommended for consumption within the first 14 d.

Atopic dermatitis (AD) is a chronic, relapsing inflammatory skin disease with critical unmet therapeutic needs. This study compared the efficacy of three probiotics-Bifidobacterium animalis subsp. lactis J12 (B. animalis J12), Lactiplantibacillus plantarum Zhang-LL (L. plantarum Zhang-LL), and Limosilactobacillus salivarius M18-6 (L. salivarius M18-6)-in a 2,4-dinitrofluorobenzene (DNFB)-induced mouse AD model. Interventions included topical fermented supernatants (J12S/Z-LL-S/M18-6-S), oral live cells (J12L/Z-LL-L/M18-6-L), and topical dexamethasone (Dex) as the positive control. Post-intervention, AD-related pathological and immunological indices were evaluated. Among the three probiotics, J12 exhibited superior efficacy, whereas L. plantarum Zhang-LL and L. salivarius M18-6 showed limited therapeutic effects. Both J12-derived formulations alleviated DNFB-induced AD symptoms: Topical J12S significantly reduced ear swelling, serum IL-4 and IL-17 levels, and increased the proportion of splenic Treg cells. Oral J12L exerted comparable immunomodulatory effects, while further improving skin pathology-epidermal thickness and mast cell infiltration were each reduced to approximately one-third of those in the model group. Additionally, J12L regulated gut microbiota by enhancing alpha diversity and altering functional predictions. Collectively, B. animalis J12 is a promising candidate for AD management: topical J12S serves as an effective, non-invasive alternative to oral J12L. Notably, the two formulations act through distinct yet complementary mechanisms-J12L exerts systemic effects via regulating immunity and the gut-skin axis, while J12S exerts local anti-inflammatory effects and protects the skin barrier-highlighting J12's versatile therapeutic potential for AD.

IntroductionColorectal cancer (CRC) remains a leading cause of cancer-related mortality. Plantaricin BM-1, a class IIa bacteriocin from Lactobacillus plantarum, exhibits anticancer potential, but its in vivo efficacy against CRC is unclear.MethodsUsing an AOM/DSS-induced CRC mouse model, we administered Plantaricin BM-1 orally and evaluated therapeutic effects via phenotypic, pathological, and inflammatory assessments. scRNA-seq elucidated molecular mechanisms, validated by RT-qPCR, IHC, flow cytometry, and Western blot.DiscussionResultsResults demonstrated that Plantaricin BM-1 significantly suppressed tumorigenesis, colon shortening, serum TNF-α levels, and pathological damage. scRNA-seq revealed a 17.38% increase in tumor-infiltrating T cells and a 9.29% expansion of cytotoxic CD8⁺ T cells. Key cytotoxic genes (Gzma, Gzmb, Fasl) were upregulated in CD8⁺ T cells, while the ERK/AP1 pathway was suppressed. Consistently, Plantaricin BM-1 downregulated ERK, AP1, and pro-apoptotic Bim in vivo and in vitro. Crucially, it inhibited CD8⁺ T cell apoptosis via the ERK/AP1 pathway.DiscussionThese findings provide mechanistic insights for developing Plantaricin BM-1 as an anti-CRC agent.

Background/Objectives: It remains unclear whether sleep deprivation induces constipation. This study aimed to evaluate the intervention effects of Bifidobacterium longum 151-1 and BN-BB01 on constipation induced by sleep deprivation in mice, and to explore the underlying mechanism from the perspective of the gut-brain axis, so as to provide a theoretical basis for probiotic intervention in sleep-related gastrointestinal dysfunction. Methods: A mouse model of sleep deprivation was established via the multiple platform water environment method. Through the detection and analysis of relevant indicators, the effects of sleep deprivation on intestinal function in mice were systematically investigated, and the changes in various indicators of mice after Bifidobacterium longum intervention were observed. Results: Sleep deprivation significantly impaired intestinal motility and intestinal mucosal barrier function in mice, reducing fecal water content by approximately 21.4%, prolonging the time to first black stool defecation by about 57 min, and decreasing goblet cell count by nearly 50%. In terms of gastrointestinal hormones and neurotransmitters, sleep deprivation significantly downregulated the levels of excitatory gastrointestinal hormones (MTL, GAS) and excitatory neurotransmitter SP by 22.3%, 14.8%, and 16.2%, respectively. Additionally, sleep deprivation promoted the secretion of the inhibitory neurotransmitter VIP and stress hormone CORT, with their levels increased by 53.1% and 23.8%, respectively. The levels of neurotransmitters including 5HT and GABA were reduced by 15.6% and 23.2%, which ultimately led to a decrease in short-chain fatty acid (SCFA) levels. Intervention with Bifidobacterium longum significantly reversed the above abnormalities. It elevated SCFA levels and upregulated the expression of SCFA receptors GPR41 and GPR109A, promoted the expression of BDNF and GDNF, inhibited HDAC activity, increased the abundance of the beneficial bacterium Akkermansia, and reduced the abundance of the harmful intestinal bacterium Alistipes. Conclusions: Bifidobacterium longum can alleviate sleep deprivation-induced constipation in mice by regulating gut-brain axis function, optimizing intestinal flora structure, modulating the secretion of gastrointestinal hormones and neurotransmitters, and repairing the intestinal mucosal barrier. This study provides a solid theoretical basis for the clinical application of probiotics in the intervention of sleep-related gastrointestinal disorders.

Rapid and accurate strain-level identification of Bifidobacterium animalis is critical for probiotic quality control and intellectual property protection in the food industry. In this study, a novel identification method for Bifidobacterium animalis subsp. lactis J12 was established by integrating single-cell Raman spectroscopy (SCRS) with machine learning (ML) algorithms. A total of 500-1000 valid single-cell Raman spectra were collected for each of five Bifidobacterium animalis subsp. lactis strains and seven heterologous lactic acid bacterial strains. The SCRS data were processed and optimized using t-distributed stochastic neighbor embedding (t-SNE), linear discriminant analysis (LDA), and support vector machine (SVM) algorithms. Results showed that stationary-phase cells exhibited the most distinctive chemical fingerprints, enabling the SVM model to identify J12 among the five target strains with an accuracy of over 99%. The established method displayed high robustness: classification accuracy and recall for lyophilized bacterial powders both exceeded 99.8%; the predicted proportions of strains in artificial mixed samples were highly consistent with theoretical values, with a mean absolute error (MAE) of < 0.5% and a correlation coefficient (R2) of > 0.998; and the identification accuracy for J12 isolates from commercial yogurt remained above 99%. Comparative genomics analysis confirmed that the unique Raman phenotypic characteristics of J12 were correlated with its specific genomic features, verifying the method's reliability at the genetic level. This label-free and pure culture-free SCRS-ML approach provides a rapid and high-precision tool for strain-specific identification in the probiotic industry, and fills the technical gap in rapid detection of highly homologous B. animalis strains.

Background: Current understanding of the biotransformation of bioactive compounds in Portulaca oleracea through probiotic fermentation remains limited, and the anti-diarrheal mechanisms of the resulting fermented products have yet to be fully elucidated. Methods: In this exploratory study, we employed untargeted metabolomics together with a senna-induced acute diarrhea mouse model to investigate P. oleracea co-fermented with Lactiplantibacillus plantarum and Bacillus subtilis. Results: Metabolomic profiling identified 220 metabolites significantly altered by fermentation, predominantly comprising increased levels of lipids, phenylpropanoids, and polyketides. Compared with the unfermented P. oleracea control, fermented P. oleracea (FP) effectively reduced the diarrhea index, lowered serum levels of inflammatory cytokines (IL-1β, IL-6, TNF-α) and neurotransmitters (5-HT, substance P), and restored Na+/K+ balance as well as ileal histomorphology. Transcriptomic analysis and RT-qPCR validation further demonstrated that FP modulated the expression of genes involved in focal adhesion, PI3K-Akt, cGMP-PKG, and mineral absorption pathways. Conclusions: Fermented P. oleracea (FP) alleviates acute diarrhea through multi-target mechanisms. Notably, fermentation endows P. oleracea with markedly superior intestinal protective effects relative to the unfermented counterpart. These findings provide preliminary experimental evidence supporting the potential of fermented P. oleracea as a candidate for intestinal protective functional food research.

Osteoporosis is a major global health challenge, particularly among aging populations, underscoring the need for safe and effective nutritional interventions. Probiotics and their metabolites have emerged as promising candidates for modulating bone health via the gut-bone axis. In this study, we investigated the effects of a cell-free culture supernatant (CFS) from the food-grade bacterium Limosilactobacillus fermentum GBE18 on the proliferation, differentiation, and mineralization of MC3T3-E1 pre-osteoblasts. GBE18 CFS exhibited no cytotoxicity at concentrations ranging from 1% to 4% (v/v). Notably, 2% (v/v) CFS significantly enhanced alkaline phosphatase (ALP) activity and extracellular matrix mineralization (p < 0.05). Transcriptomic profiling revealed that differentially expressed genes were enriched in osteoblast-related processes and two key signaling pathways: Wnt/β-catenin and PI3K/Akt. Subsequent qRT-PCR and Western blot analyses confirmed the upregulation of critical regulators (Rspo2, Pdpk1, Malat1) and demonstrated coordinated activation of Akt phosphorylation, β-catenin stabilization, and Runx2 protein expression. Our findings indicate that GBE18 CFS promotes osteogenic differentiation through coordinated modulation of the PI3K/Akt and Wnt/β-catenin pathways. Consequently, this study provides mechanistic evidence supporting the potential application of L. fermentum GBE18-derived metabolites as functional food ingredients or dietary interventions for bone health and osteoporosis management.

Colorectal cancer (CRC) ranks as the third most prevalent and lethal cancer globally, yet the impact of antibiotics on gut microbiota during CRC progression is not well understood. Microorganisms in tumors, with uncertain origins, influence tumor heterogeneity, treatment sensitivity, immune response, and drug resistance. We conducted an initial study on the effects of the oral probiotic Lactobacillus plantarum Zhang-LL on CRC progression in mice, examining intestinal balance, disease-related changes, host metabolism, and gene expression in intestinal tissues. Furthermore, we hypothesized that under antibiotic-driven conditions, a link could be established among intestinal microbiota, arachidonic acid metabolism, and intratumoral microorganisms. The results showed that these were driven by vancomycin, aztreonam, and quadruple antibiotics. Mice in different treatment groups were exposed to the intestinal environment. Lactobacillus plantarum Zhang-LL treatment reshaped the intestinal microbiota structure and improved intestinal stability to achieve anti-CRC effect, and the specific intestinal microbiota structure caused the inhibition of the lipoxygenase subpathway in arachidonic acid metabolism, obstruction of upstream linoleic acid metabolism, and establishment of a new microenvironmental equilibrium in the intratumoral microbial community. This study revealed that Lactobacillus plantarum Zhang-LL was driven by antibiotics to improve the tumor microenvironment through the gut microbiota-intratumoral microbial axis to alleviate CRC progression.

Due to the high incidence of periodontal diseases in pet cats and dogs, the purpose of this study is to screen bacteria with beneficial oral health effects and assess the effectiveness of its freeze-dried cell. In this study, we explored the effects of oral probiotics by determining the bacteriostatic ability, percentages of self-aggregation and co-aggregation in vitro, and through microbial community analysis, the alleviating effect of freeze-dried cells on periodontitis and its mechanism of action were evaluated. Lactobacillus zeae N165 significantly inhibited Fusobacterium nucleatum and Porphyromonas gingivalis, and it had high co-aggregation rates of 96.78% and 88.94% with F. nucleatum and P. gingivalis, respectively. In vivo, freeze-dried L. zeae N165 cells significantly reduced alveolar bone resorption, TNF-α, and IL-6 levels in rats with periodontitis, maintained a healthy oral and intestinal microbial community structure, and regulated the dominant species to alleviate periodontitis. The prediction of functions by the KEGG database analysis of oral flora revealed that freeze-dried L. zeae N165 cells may alleviate periodontitis via four pathways: reduction of glutamine degradation, modulation of lipopolysaccharide levels, biosynthesis of polyketide glycan units, and biotin metabolism. L. zeae N165 showed promising results in both in vitro and in vivo experiments, suggesting new directions for the oral probiotics industry.

Pseudomonas aeruginosa is a ubiquitous opportunistic pathogen of significant clinical and public health concern, necessitating the development of rapid and reliable detection methods. Traditional diagnostic approaches, which rely on culture-dependent techniques and biochemical identification, are often labor-intensive, time-consuming, and technically demanding. This study describes a novel single-tube, two-step, rapid detection platform that integrates recombinase polymerase amplification (RPA) with clustered regularly interspaced short palindromic repeats-associated protein Cas12b technology. Through systematic experimental optimization, the study identified an optimal RPA primer pair (F2-R1) and single-guide ribonucleic acid 553 that targets the lasR gene of P. aeruginosa, with reaction conditions optimized at 42°C and a primer concentration of 10 μM. The RPA-clustered regularly interspaced short palindromic repeats/Cas12b fluorescence detection system (RPA-Cas12b-Fluo) demonstrated a sensitivity threshold of 10 copies of deoxyribonucleic acid (DNA) per reaction and a bacterial detection limit of 50 colony-forming units (CFU) per reaction. When coupled with a lateral flow strip (RPA-Cas12b-LFS), the sensitivity was slightly reduced but remained robust, achieving detection limits of 10² copies and 200 CFU per reaction. Specificity assays confirmed a high discriminatory capacity for P. aeruginosa with no cross-reactivity observed against P. fluorescens, P. putida, or six common foodborne pathogens, thereby validating the specificity profile of the platform. The applicability of the method was further validated by analyzing 20 water samples, which demonstrated 100% concordance with the national standard culture method. These findings have significant implications for improving outbreak surveillance and mitigating the risk of foodborne transmission associated with P. aeruginosa.

An imbalance between oxidative and antioxidant processes in the host can lead to excessive oxidation, a condition known as oxidative stress (OS). Although changes in the hindgut microbiota have been frequently linked to OS, the specific microbial and metabolic underpinnings of this association remain unclear. In this study, we enrolled 81 postpartum Holstein cows and stratified them into high oxidative stress (HOS, n = 9) and low oxidative stress (LOS, n = 9) groups based on the oxidative stress index (OSi). Using a multi-omics approach, we performed 16S rRNA gene sequencing to evaluate microbial diversity, conducted metagenomic analysis to identify functional bacteria, and utilized untargeted metabolomics to profile serum metabolites. Our analyses revealed elevated levels of kynurenine, formyl-5-hydroxykynurenamine, and 5-hydroxyindole-3-acetic acid in LOS dairy cows. Additionally, the LOS cows had a higher abundance of short-chain fatty acids (SCFAs)-producing bacteria, including Bacteroidetes bacterium, Paludibacter propionicigenes, and Phascolarctobacterium succinatutens (P. succinatutens), which were negatively correlated with OSi. To explore the potential role of these bacteria in mitigating OS, we administered P. succinatutens (108 cfu/day for 14 days) to C57BL/6 J mice (n = 10). Oral administration of P. succinatutens significantly increased serum total antioxidant capacity, decreased total oxidants, and reduced OSi in mice. Moreover, this treatment promoted activation of the Nrf2-Keap1 antioxidant pathway, significantly enhancing the enzymatic activities of GSH-Px and SOD, as well as the concentrations of acetate and propionate in the colon. In conclusion, our findings suggest that systemic tryptophan metabolism and disordered SCFAs production are concurrent factors influenced by hindgut microbiota and associated with OS development. Modulating the hindgut microbiota, particularly by introducing specific SCFAs-producing bacteria, could be a promising strategy for combating OS.

Aflatoxin B1 (AFB1) is a secondary metabolite produced by fungi, such as Aspergillus flavus and Aspergillus parasiticus, which are extremely toxic and carcinogenic. In this study, we focused on investigating the degradation of AFB1 under X-ray irradiation and explored the underlying mechanisms of this process. Our results indicated that the degradation rate of AFB1, which was initially present at a concentration of 5 mu g/mL in acetonitrile solvent, increased in a manner dependent on the irradiation dose, and when the irradiation dose reached 10 kGy, the degradation rate could reach as high as 81%. Moreover, under an irradiation dose of 10 kGy, AFB1 in acetonitrile with initial concentrations of 5, 10, and 20 mu g/mL exhibited varying degradation rates of 81%, 77%, and 38%, respectively. Six degradation products of AFB1 treated with 10 kGy irradiation were identified: A (C14H10O6), B (C17H14O8), C (C16H10O5), D (C16H12O7), E (C14H10O5), and F (C18H16O8). Based on the information from these degradation products, we speculate that there may be three degradation pathways for AFB1 under X-ray irradiation: The first and third pathways initially involve an addition reaction at the C(8)-C(9) furan ring double bond of AFB1, followed by other reactions. In contrast, the second pathway is believed to entail the direct elimination of the methoxy group from the side chain of the benzene ring of AFB1 during the course of irradiation. Finally, in vitro hepatocyte experiments demonstrated that AFB1 subjected to X-ray irradiation exhibited reduced toxicity towards human hepatocellular carcinoma cells, as compared to untreated AFB1.

This study elucidates the anti-colorectal cancer (CRC) mechanism of Rosa rugosa cv. Plena polysaccharide RPP1 against AOM/DSS-induced carcinogenesis. Purified via water extraction and chromatography, RPP1 was characterized as an eight-monosaccharide polymer by HPLC. In CRC mice, RPP1 administration reduced colonic polyp formation and ameliorated colon shortening while normalizing elevated serum IL-1β and TNF-α levels. Integrated multi-omics analyses revealed RPP1 remodeled gut microbiota composition through suppression of pro-inflammatory Bacteroides and Desulfovibrio concurrent with enrichment of beneficial Eubacterium and Muribaculum. These microbial shifts were associated with downregulation of fecal phosphatidylcholine (PC) and lysophosphatidylcholine (LPC), perturbing ether lipid, glycerophospholipid and sphingolipid metabolism. Mechanism correlation analysis further indicated Muribaculum/Clostridium modulation mediated RPP1’s regulation of LPC levels. Transcriptomics confirmed suppression of lipid-metabolism pathways alongside activation of NOD-like receptor (NLR) and PPAR immune signaling. Collectively, RPP1 alleviates CRC through multifaceted modulation of gut microbiota, lipidomic remodeling, and immune pathway activation.

To investigate the "microbial terroir" in vineyard of Beijing and its effect on the flavor of wine fermented by cold-resistant grapes, the microbial community from vineyard to fermentation both in spontaneous fermentation and fermentation with commercial yeast was investigated by High-throughput Sequencing. The flavor dynamics were analyzed by Gas Chromatography-Ion Mobility Spectrometer. Results showed that Acinetobacter, Pseudomonas and Gluconobacter derived from grapes entered to fermentation and became the dominant bacterial genera. Hanseniaspora from grapes gradually decreased and Saccharomyces became the dominant fungus in the late fermentation stage. A total of 55 typical volatile flavor compounds were detected during fermentation. Two-way Orthogonal Partial Least Squares were applied to reveal the correlation between microorganisms and flavor substances. A total of 8 fungal genera and 17 bacterial genera were strongly correlated with volatile organic compounds during wine fermentation. Saccharomyces was positively correlated with 1-penten-3-ol, ethyl butanoate, ethyl hexanoate M, and butanone, but negatively correlated with isobutyl propionate and acrolein. Hanseniaspora had a strong positive correlation with six flavor compounds: 1-hexanol, ethyl isobutyrate D, ethyl 3-methylbutanoate, ethyl hexanoate, butanal D, and 2,2,4,6,6-pentamethylheptane. This research provided the basis for the development and utilization of indigenous microorganisms in the vineyards of Beijing.

Introduction:Plantaricin BM-1 is a class IIa bacteriocin active against Escherichia coli. However, the mode of action of class IIa bacteriocins against gram-negative bacteria remains unclear. In this study, the regulatory role of sigma factor FliA (σ28) in the antibacterial mechanism of plantaricin BM-1 against E. coli K-12 BW25113 is evaluated. Methods:The fliA-complemented strain of E. coli JW1907, namely E. coli ReJW1907, was constructed through λ-Red homologous recombination. The effects of plantaricin BM-1 on E. coli growth, cell morphology, and membrane integrity were investigated using growth curves, electron microscopy, and flow cytometry. The biofilm formation ability of E. coli was evaluated using crystal violet staining and confocal laser scanning microscopy. Transcriptomic analysis was performed to screen for differentially expressed genes (DEGs). Results and discussion:The inhibition rate (I%) of plantaricin BM-1 (3.75 mg/mL) against E. coli JW1907 (89.22 ± 1.13%) at the 8th h of culture was significantly higher than that of E. coli BW25113 (70.36 ± 6.30%) and ReJW1907 (74.75 ± 4.99%). The biofilm biomass produced by E. coli BW25113 (OD595 nm = 0.343 ± 0.056) was significantly reduced to 0.227 ± 0.04 after fliA deletion, and was recovered to its original level (0.358 ± 0.027) after fliA complement. A total of 205 DEGs were identified between E. coli BW25113 and JW1907. Among these, four DEGs (fliZ,wza, lsrR, and pgaA) were enriched in the biofilm formation pathway. Further analysis revealed eight up-regulated DEGs (lsrKRBDCAFG), which were significantly enriched in the LuxS/AI-2 quorum sensing (QS) system. After the deletion of any gene from lsrKRBDCAFG, the I% of plantaricin BM-1 against E. coli BW25113 (70.77 ± 7.01%) was significantly increased to 80.68-90.06%, with its biofilm production (0.254 ± 0.014) reduced to 0.135-0.188. In conclusion, FliA modulates biofilm formation through the LuxS/AI-2 QS system, thereby regulating the antibacterial activity of plantaricin BM-1. Overall, these findings improve our understanding of the bacteriostatic mechanism of class IIa bacteriocins against gram-negative bacteria.

Plantaricin BM-1 exhibits antibacterial activity against Escherichia coli; however, the underlying mechanism remains unclear. This study aimed to investigate the function of PotF, a putrescine-binding protein, in regulating the antibacterial activity of plantaricin BM-1 against E. coli K12. The antibacterial activity of plantaricin BM-1 against E. coli K12 and JW0838 cells was assessed using growth curves. The differences in biofilm formation between the two E. coli strains were evaluated by crystal violet staining and confocal laser scanning microscopy. The effects of plantaricin BM-1 on E. coli morphology and cell membrane integrity were investigated by electron microscopy and lactate dehydrogenase release assays. Proteomics was used to screen for differentially expressed proteins (DEPs) that are potentially involved in regulating the antibacterial mechanism. The null mutation of potF enhanced the antibacterial effects of plantaricin BM-1 on E. coli, and caused a significant decrease (p < 0.05) in the biofilms of E. coli JW0838. The plantaricin disrupted the cell membrane of E. coli JW0838. Proteomic analysis revealed that potF mutation significantly affected several DEPs involved in biofilm formation. Plantaricin BM-1 exhibited significantly enhanced antibacterial activity against biofilm-associated gene mutants compared to wild-type E. coli K12. These findings enhance our understanding of the bacteriostasis of class IIa bacteriocins against Gram-negative microorganisms.

Microbially contaminated food can cause serious health hazards and economic losses, therefore sensitive, rapid, and highly specific visual detection is called for. Traditional detection of microorganisms is complex and time-consuming, which cannot meet current testing demands. The emergence of paper-based biosensors provided an effective method for efficient and visual detection of microorganisms, due to its high speed, all-in-one device, low cost, and convenience. This review focused on 5 biomarkers, namely nucleic acids, proteins, lipopolysaccharides, metabolites, and the whole microorganism of microorganisms. Besides, the recognition methods were summed up in 5 forms, including immunological recognition, aptamer recognition, nucleic acid amplification-mediated recognition, DNAzyme recognition and clustered regularly interspaced short palindromic repeats mediated recognition. In addition, we summarized the applications of paper-based biosensors in the detection of microorganisms thoroughly. Through the exploration of different biomarkers, identification methods, and applications, we hope to provide a reference for the development of paper-based biosensors and their application in safeguarding the food chain.

Chinese sour bamboo shoot is a traditionally, spontaneous fermented food that is particularly popular due to its complex and distinctive flavor. The volatile compounds of sour bamboo shoot originate mainly from the raw materials and the microbial fermentation. To reveal the correlation between microorganisms and flavor, third-generation sequencing and Gas Chromatography-Ion Mobility Spectrometry were applied to analyze the dynamics of microbial communities at the species level and volatile compounds during sour bamboo shoot fermentation. The abundance of Lactobacillus acetotolerans and Lactobacillus fermentum increased during the fermentation, while Lactobacillus amyloliquefaciens decreased at first but then began to rise. At the end of fermentation, Lactobacillus amyloliquefaciens and Lactobacillus acetotolerans became the predominant species. A total of sixty-seven volatile compounds, which included twenty-three esters, nineteen alcohols, eight ketones, six aldehydes, six aromatic hydrocarbons, four acids and one ether, were identified. These compounds constituted the primary flavor of sour bamboo, which created a complex flavor of sour bamboo shoot. Among them, the contents of acetic acid, propionic acid, and isoamyl alcohol gradually increased during the fermentation process, and they became the main volatile compounds. Furthermore, the correlation between microorganisms and volatile compounds was investigated through two-way Orthogonal Partial Least Squares (O2PLS), which revealed a positive correlation between Lactobacillus amylolyticus and ethyl propanoate. Additionally, the abundance of Lactobacillus acetotolerans and Lactobacillus fermentum was found to be positively correlated with 2-heptenal. These findings provide a theoretical basis for understanding the formation mechanism of sour bamboo shoot flavor and the standardized production of high-quality sour bamboo shoots.