In Vitro Degradation of Uric Acid and Its Precursors by Limosilactobacillus fermentum DF2 Isolated from Salt-Free Pickled Vegetables Produced in Guizhou Province of China

Hyperuricemia (HUA) is a metabolic disorder characterized by elevated serum uric acid (UA) levels resulting from the dysregulation of purine metabolism. The use of lactic acid bacteria (LAB) to alleviate HUA has attracted considerable attention. This study aimed to isolate LAB capable of degrading UA and purine precursors from traditionally fermented salt-free pickled vegetables in Guizhou Province, China, to evaluate their degradation characteristics, and to explore the underlying metabolic mechanism. A strain designated DF2 was isolated and identified as Limosilactobacillus fermentum (L. fermentum). In vitro experiments at 37 °C for 1 h showed that the DF2 strain could completely degrade guanosine, inosine, and adenosine, whereas its degradation rates for UA, xanthine, hypoxanthine, adenine, and guanine were 1.99%, 3.03%, 2.17%, 3.79%, and 12.12%, respectively. Notably, the strain converted the nucleosides to their purine bases and fully degraded guanosine-derived guanine within 7 h. Genomic analysis identified genes responsible for purine metabolism in the DF2 genome (accession number: SAMN62640203), and a metabolic pathway of UA and its precursors in the DF2 strain was proposed. These findings not only expand microbial resources for degrading UA and its precursors but also provide a basis for developing microbial agents to control UA levels in HUA.