Cold-Adapted Uric Acid-Degrading Lacticaseibacillus paracasei NEFU-6 Application in Kimchi "Paocai"

The use of lactic acid bacteria for the management of hyperuricemia has attracted growing interest, whereas the specific emphasis on cold-adapted uric acid-degrading probiotics in the fermentation of traditional foods remains underexplored. In this study, Lacticaseibacillus paracasei NEFU-6 was isolated from Northeastern Chinese Kimchi and efficiently degraded uric acid (UA) at a temperature relevant to food fermentation (15 °C) and under simulated physiological conditions (37 °C). The results showed that strain NEFU-6 degraded 25.48% of UA in 6 days at 15 °C, and 40.55% after 72 h at 37 °C in 0.84 g/L of uric acid. All probiotic and safety-related properties were evaluated at 37 °C to simulate human physiological conditions. In vitro probiotic characterization revealed that strain NEFU-6 exhibits non-hemolytic activity, strong free radical-scavenging capacity, significant surface hydrophobicity, and an auto-aggregation rate of 52.65% after 24 h. The strain NEFU-6 also demonstrated robust survival under simulated gastrointestinal conditions, with tolerance rates of 70.7% in 0.3% bile salts, 51.02% in gastric juice at pH 1.5, and 62.61% after 4 h of exposure to artificial intestinal fluid, indicating strong adaptability. Furthermore, the application of strain NEFU-6 in kimchi fermentation improved product quality, confirming its potential for the development of low-temperature functional foods.