From Efficacy to Process: Uric-Acid-Lowering Effect of Limosilactobacillus reuteri W6-12 and Its Production Process Optimization

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.