Ling Chen

Maintaining the viability of Bifidobacterium longum B18 throughout lyophilization and storage remains a key challenge for its application as a probiotic ingredient in functional foods. This study screened 18 lyoprotectants, optimized trehalose (TRE) and galacto-oligosaccharide (GOS) concentrations, and evaluated post-drying survival, enzyme activities, membrane integrity, morphology, and 90-day storage stability. The 8% (w/v) TRE + 3% (w/v) GOS formulation yielded the highest post-freeze-drying survival (90.6%). It also showed higher post-drying Na⁺/K⁺-ATPase, Ca²⁺/Mg²⁺-ATPase, lactate dehydrogenase, and β-galactosidase activities than the PBS control, although responses relative to the individual protectants varied by enzyme. Qualitative fluorescence and scanning electron microscopy observations indicated limited propidium iodide-positive staining and less apparent surface damage. During storage, viability decreased in all formulations. Based on descriptive comparisons, viability retention was numerically greater at 4 and −20 °C than at 25 °C. After 90 days, the combined formulation retained 49.4% and 45.7% survival at −20 and 4 °C, respectively, compared with 38.8% and 35.8% for TRE and 30.2% and 20.3% for GOS. At 25 °C, survival decreased to 0.1%. However, because the formulations differed in total added lyoprotectant concentration, the observed differences do not establish complementary or synergistic protection by TRE and GOS. These findings support further evaluation of 8% TRE + 3% GOS for refrigerated or frozen functional foods. However, this preliminary 90-day study does not establish commercial shelf-life suitability, which requires validation in representative food matrices under commercial processing, packaging, and longer-term storage conditions.

Clinical chemical drugs for hyperuricemia (HUA) often cause side effects including liver and kidney injury. Developing safe and effective probiotic preparations for HUA intervention is of considerable application value. However, the large-scale production of probiotics faces two major bottlenecks: low viable cell density during fermentation and poor survival after lyophilization. This study integrated in vivo efficacy evaluation and mechanism exploration with the production process optimization for Limosilactobacillus reuteri W6-12. We first verified its hypouricemic effect in vivo, then adopted response surface methodology to optimize fermentation medium components and composite cryoprotectant formulations, and further evaluated the efficacy of the obtained lyophilized probiotic powder using a rat model of HUA. In HUA rats, W6-12 treatment significantly decreased serum UA (SUA) levels, an effect attributed to hepatic xanthine oxidase inhibition and renal downregulation of GLUT9 and URAT1, alleviation of kidney oxidative stress and inflammation, and reshaping of gut microbial composition and associated metabolites, likely via the gut microbiota-bile acid axis. The optimized medium (sucrose 31 g/L, yeast extract 26 g/L, sodium acetate 7.5 g/L) yielded 2.03 × 10⁹ CFU/mL, a 1.6-fold increase over the unoptimized condition. The optimal composite cryoprotectant consisted of 8% L-sodium glutamate, 10% trehalose, and 12% skim milk powder, achieving a lyophilization survival rate of 89.47%. Low, medium, and high doses of lyophilized W6-12 all exerted dose-dependent urate-lowering effects in HUA rats. In conclusion, the lyophilized powder of L. reuteri W6-12 is a promising probiotic preparation for UA management.

Sleep disorders represent a growing public health concern, yet current pharmacological interventions are limited by tolerance, dependence, and rebound insomnia. This study evaluated the probiotic properties of Bifidobacterium longum B18 and its effects on pharmacologically induced sleep parameters in male Sprague–Dawley rats, focusing on tryptophan-related metabolism and gut microbiota composition. In vitro, B18 exhibited favourable probiotic characteristics, no detectable haemolytic activity, and susceptibility to all eight antimicrobials tested. In vivo, B18 significantly shortened barbital sodium-induced sleep latency and prolonged pentobarbital sodium-induced sleep duration (p < 0.05). Targeted metabolomic profiling of faeces, plasma, and hippocampus showed increased tryptophan and melatonin concentrations, whereas 5-HTP and 5-HT remained unchanged. B18 was also associated with lower Kyn/Trp ratios, although plasma Kyn concentrations were unchanged. Increased MT/5-HT ratios and elevated hippocampal AANAT levels were also observed, supporting an association with enhanced melatonin-related metabolism. Gut microbiota analysis showed higher abundances of Bifidobacterium and Lactobacillus in the B18 group than in the DZP group, together with lower Desulfovibrio abundance than in the CTR. Exploratory correlation analysis further showed positive associations of Bifidobacterium abundance with faecal tryptophan and melatonin levels and an inverse association with the Kyn/Trp ratio. Collectively, these findings indicate that B. longum B18 modifies pharmacologically induced sleep parameters in association with altered tryptophan–melatonin metabolism and gut microbiota composition, supporting further evaluation of B18 as a candidate probiotic for sleep-related functional applications.

The growing global protein demand and environmental concerns from conventional animal agriculture have driven the exploration of sustainable alternative protein sources. Single-cell proteins (SCPs) from microbial fermentation offer a promising solution. This study comprehensively evaluated the nutritional value and safety profile of SCP produced from Ralstonia eutropha H16 through integrated in vitro and in vivo assessments. Nutritional analyses revealed a high crude protein content of 71.87 ± 5.05 g/100 g dry weight, with total amino acids of 53.67 ± 1.05 g/100 g. The essential amino acid content was 24.38 ± 0.51 g/100 g, accounting for 45% of the total amino acids. An essential amino acid index (EAAI) of 1.46 ± 0.04 and an amino acid score (AAS) of 0.83 ± 0.06 confirmed its classification as a high-quality protein source according to FAO/WHO standards. In vivo rat feeding trials demonstrated an adjusted protein efficiency ratio (PER) of 1.81, exceeding common plant proteins such as wheat (0.8–1.1). True digestibility (TD) reached 85.73%, with a biological value (BV) of 49.37%, net protein utilization (NPU) of 42.33%, and protein digestibility-corrected amino acid score (PDCAAS) of 0.71. Comprehensive safety assessments included chemical contaminant screening, acute oral toxicity studies in rats and mice, in vitro chromosome aberration tests, and erythrocyte micronucleus tests. Heavy metals and aflatoxin B₁ levels were below regulatory limits. Acute oral toxicity studies established LD₅₀ values exceeding 10,000 mg/kg body weight in both rodent species, classifying this protein source as practically non-toxic. The 28-day sub-acute toxicity study showed no significant adverse effects at low doses (6.25% protein replacement). Both genotoxicity assays (mammalian cell chromosome aberration assay and mammalian erythrocyte micronucleus test) returned negative results. These findings establish R. eutropha H16-derived SCP as a safe, nutritious, and sustainable protein source with considerable potential for feed and food applications, contributing to global food security and environmental sustainability.

Background . Helicobacter pylori infection is a major risk factor for gastric cancer (GC), especially in East Asia. However, the mechanisms through which bacterial strain heterogeneity contributes to GC risk remain poorly understood. This study aims to elucidate the roles of specific virulence factors, antibiotic resistance profiles and genetic variations in H. pylori in GC development. Methods. We integrated host clinical data with phenotypic and genomic analyses of 31 clinical H. pylori isolates. Genomic analysis was performed to determine phylogenetic lineage and virulence markers. Antibiotic susceptibility and biofilm-forming ability of the clinical isolates were also assessed, and a genome-wide association study (GWAS) was employed to identify genetic polymorphisms linked to GC risk. Results. Among the isolates, 93.5 % of isolates belonged to the East Asian lineage and carried high-risk virulence markers ( cagA EPIYA-ABD, vacA s1m1). However, multidrug resistance was observed in 64.5 % of isolates, with high resistance rates to metronidazole (71.0%) and levofloxacin (48.4%) exceeding global averages. Strong biofilm-forming strains were significantly associated with tetracycline resistance compared to weak biofilm-forming strains. Additionally, GWAS identified five SNPs significantly associated with GC risk, with variants in hemC , babB and C694_RS04850 being enriched in high-risk strains. Conclusions. This study demonstrates the critical impact of H. pylori strain diversity in GC development, emphasizing the necessity for region-specific surveillance and innovative therapeutic strategies.

Staphylococcus aureus, as a critical zoonotic and foodborne pathogen, not only triggers public health threats such as food poisoning but also acts as a leading cause of diverse clinical infections, including skin infections, pneumonia, and endocarditis. Confronted with the growing crisis of multidrug resistance in S. aureus, both phage therapy and probiotic therapy have emerged as promising alternative biological strategies; however, the current literature predominantly examines them in isolation. This review therefore aims to delineate the contemporary therapeutic challenges of drug-resistant S. aureus and to systematically compare the mechanisms and clinical translation of phages and probiotics within an integrated analytical framework. We first outline the current therapy landscape, then present side by side the molecular inhibitory mechanisms and clinical progress of both approaches, followed by a comparative analysis of their antibacterial mechanisms, clinical efficacy, and industrial challenges. Through this consolidated perspective, the review not only clarifies the distinct strengths and limitations of each strategy but also seeks to provide researchers and clinicians with a comprehensive mechanistic and evidence-based reference for developing novel antibacterial technologies and designing innovative therapeutic regimens. Ultimately, it highlights potential synergies between phages and probiotics, offering a forward-looking roadmap to overcome S. aureus resistance and advance personalized combinatorial therapies.

Ochratoxin A (OTA), a fungal secondary metabolite, is frequently detected in grains, herbal products, and other agricultural commodities, posing potential food safety risks. Among existing detoxification strategies, biological degradation is considered both specific and environmentally sustainable. In this study, a novel OTA-degrading bacterium, Brevibacillus parabrevis S09T2, was isolated from soil using OTA as the sole carbon source. The strain exhibited no hemolytic activity and carried no virulence or antibiotic resistance genes, indicating a favorable safety profile. S09T2 efficiently degraded OTA, removing over 93% of 5–8 μg/mL OTA within 24 h at 37 °C, and almost completely degrading OTA concentrations up to 10 μg/mL within 72 h. UPLC-HRMS analysis identified ochratoxin α (OTα) and phenylalanine as the only degradation products, confirming detoxification via amide bond hydrolysis. The intracellular enzyme responsible for this reaction displayed notable thermostability, achieving near-complete degradation of 1 μg/mL OTA at 50 °C within 6 h. Moreover, the cell lysate significantly reduced OTA levels in Plumeria rubra extract, a widely consumed functional food, demonstrating applicability in complex food matrices. Collectively, these findings highlight S09T2 as a promising candidate for OTA detoxification and support its potential use in food and feed safety applications.

Edible and medicinal substances can be contaminated by fungi during harvesting, processing, and storage, leading to mycotoxin production and quality deterioration. The distribution of mycotoxigenic fungi in edible and medicinal substances was investigated in this study. Fungi and mycotoxins were detected in 163 commercially available edible and medicinal substances using standard microbiological techniques and high-performance liquid chromatography. A total of 92.0% of samples contained fungi (0.5–5.3 lg colony-forming units (CFU)·g⁻¹); 208 fungal strains belonging to 16 genera were identified, predominantly Aspergillus and Penicillium. Aspergillus section Nigri (30.3%) produced fumonisin B₂, which was distributed mainly in radix and rhizome samples. Thirteen samples had mycotoxins, of which ochratoxin A was the most common, followed by aflatoxins and zearalenone (ZEN). One Nelumbinis semen sample contained 10.75 μg·kg⁻¹ AFB₁, and one Raisin tree semen sample contained 484.30 μg·kg⁻¹ ZEN, which exceeded regulatory limits in Europe and China. These findings highlight the potential risks associated with fungal contamination and mycotoxins in edible and medicinal substances. Enhanced quality control measures are essential to reduce contamination during harvesting, processing, and storage. Expanded mycotoxin screening, improved preservation techniques, and stricter regulatory standards need to be implemented to ensure consumer safety.