Novel FAD-dependent uricase produced by food-sourced Priestia megaterium and activity assessment using hyperuricemia Caenorhabditis elegans

The global rise in hyperuricemia (HUA) has driven the quest for safe, non-pharmacological interventions. Food-grade probiotics with HUA-mitigating potential are particularly promising. We isolated a novel strain, SSY-7-2, from traditional fermented wheat pastes, which exhibited robust uric acid (UA) degradation activity. SSY-7-2 showed high average nucleotide identity (ANI) values of 98.76–99.60 % with Priestia megaterium , surpassing the species delineation threshold. Whole-genome sequencing revealed complete UA degradation and purine metabolism pathways. We identified gene SSY_004365 as encoding an FAD-dependent urate hydroxylase (HpmO, E.C. 1.14.13.113), with a Km of 27.36 μM and a Kcat/Km of 5.74 × 10 4  s −1  M −1 . Using UA as the sole nitrogen source, we partially elucidated a conserved HpmO-UraD-HiuH cascade for UA hydrolysis in P. megaterium . Both in vitro and Caenorhabditis elegans models confirmed SSY-7-2's UA degradation activity, safety, and probiotic attributes. These findings expand the bioactivity spectrum of Priestia megaterium and position SSY-7-2 as a promising complementary probiotic for hyperuricemia management.