Genomic insights and functional evaluation of Lacticaseibacillus paracasei EG005: a promising probiotic with enhanced antioxidant activity

Probiotic attributes, antioxidant and neuromodulatory effects of GABA-Producing Lactiplantibacillus plantarum SY1 and optimization of GABA production

Γ-aminobutyric acid (GABA), a major inhibitory neurotransmitter in the central nervous system, has been shown to alleviate various physiological disorders including insomnia, hypertension, depression, and memory loss. Lactic acid bacteria (LAB), recognized as safe GABA producers, have attracted increasing attention. This study aimed to screen GABA-producing LAB from naturally fermented dairy products and evaluate their probiotic potential, antioxidant and neuromodulatory activities, while optimizing GABA production. GABA-producing LAB were screened using the Berthelot method and thin-layer chromatography. The safety of Lactiplantibacillus plantarum SY1 was assessed through hemolysin production and drug sensitivity tests. L. plantarum SY1 demonstrated high tolerance to acidic conditions and low bile salt concentrations, along with significant antioxidant capacity (49 ± 0.2% DPPH radical scavenging rate, 86.1 ± 0.14% hydroxyl radical scavenging rate, and 32.7 ± 1.6% superoxide radical anion scavenging rate). In vivo experiments revealed that L. plantarum SY1 extended the lifespan of C. elegans N2, enhanced oxidative stress resistance, and delayed paralysis in transgenic C. elegans (CL4176) by 23.53%. Through OFAT strategy and RSM optimization, GABA production reached 1.49 g/L under optimal conditions (37℃, pH 4.44, 96 h fermentation, and 4.16% inoculum). These findings demonstrate that L. plantarum SY1 is a promising GABA-producing strain with antioxidant and neuromodulatory effects, suggesting its potential as an anti-aging and neuroprotective probiotic.

Whole-Genome Sequence Analysis, Probiotic Potential, and Safety Assessment of the Marine Bacterium Paraliobacillus zengyii CGMCC1.16464

Paraliobacillus zengyii CGMCC1.16464 (P. zengyii) is a novel antiviral probiotic candidate strain. To ensure its safety as a potential probiotic, a safety evaluation was conducted in this study. The safety and functional potential of P. zengyii were systematically assessed through genomic bioinformatics analysis, in vitro experiments, and acute oral toxicity tests in mice. Genomic analysis revealed that P. zengyii is rich in genes related to carbohydrate and amino acid metabolisms and carries genes encoding antimicrobial and antiviral agents (such as ectoine, type III polyketide synthase, and lasso peptides). It also expresses gastrointestinal tolerance-related proteins (ClpC, GroEL, and ClpP). Its resistance to polymyxins is an inherent trait with no risk of plasmid-mediated transfer. In vitro experiments confirmed that P. zengyii is somewhat tolerant to bile salts and acidic environments and does not exhibit hemolytic or gelatinase activity. Importantly, an acute oral toxicity test in mice revealed that after intervention with high, medium, or low doses, no significant abnormalities in the body weight, organ index, or tissue morphology of the mice were observed. In conclusion, P. zengyii exhibited good safety and probiotic potential in terms of genomic safety, metabolic function, and in vitro and in vivo toxicities, providing a theoretical basis for the development of novel functional probiotics.

Safety Evaluation of Human-Derived Uric Acid Degrading Lacticaseibacillus paracasei M2a and Its Impact on Gut Microbiota

We report the identification of a human-derived uric acid (UA)-degrading bacterial strain, analyzed its degradation efficiency, and assessed its safety to provide a scientific basis for future clinical applications in the treatment of hyperuricemia (HUA) and gout. Here, we isolated the M2a strain from feces of healthy young men. The strain was identified as Lacticaseibacillus paracasei (formerly Lactobacillus paracasei) via 16S rRNA and biochemical analyses. The in vitro and in vivo efficiencies of M2a uric acid degradation were found to be 45.53% and up to 47.88%, respectively. Strain M2a exhibited no detectable pathogenicity, demonstrated robust tolerance to simulated gastrointestinal conditions, and displayed a favorable safety profile. The strain ameliorated hyperuricemia-associated liver and kidney dysfunction, as evidenced by improved biochemical markers (ALT, AST, BUN, and CRE; P < 0.05) and histopathological findings showing reduced inflammatory cell infiltration and preserved tissue architecture in HE-stained liver and kidney sections. Furthermore, it regulated intestinal microbiota in HUA mice, increased the relative content of beneficial bacteria (e.g., Lacticaseibacillus) in the mouse intestine, and reduced the intestinal presence of Klebsiella and Blautia in mice. Further study of M2a is warranted to elucidate pathways for lowering blood levels of uric acid via clinical utilization of probiotic and associated biologic interventions.