Abstract
Sour soup, a traditional fermented specialty from Northeast China, is renowned for its distinctive aroma and various health benefits. Here, we report the probiotic properties of Lactiplantibacillus plantarum Z45-a strain isolated from sour soup broth-along with its fermentative potential in sour soup production. This strain is suitable for food fermentation due to its absence of biogenic amine production and non-hemolytic activity. It exhibited strong tolerance to simulated gastrointestinal conditions and demonstrated high adherence capability to Caco-2 cells. Additionally, the strain displayed antioxidant and antimicrobial activities. Whole-genome sequencing revealed that Z45 carries no virulence or antibiotic resistance genes. It also harbors multiple carbohydrate-active enzymes and a complete folate biosynthesis pathway, alongside genes associated with stress response, antioxidant activity, and adhesion. Subsequently, Z45 was employed as a starter culture for sour soup fermentation, and its effects on the physicochemical and sensory properties of the product were evaluated. The results indicated that fermentation with Z45 did not alter the physicochemical properties of sour soup but significantly enhanced its sensory attributes. Compared to spontaneous fermentation, Z45-fermented sour soup showed reduced levels of harmful biogenic amines, improved flavor and overall sensory quality, notable enrichment of Lactobacillus and Oscillospirales in the microbial community, and upregulation of beneficial metabolites such as flavonoids and glycerophosphocholine. In summary, Lactiplantibacillus plantarum Z45 is safe, demonstrates probiotic potential, and holds promise for improving the quality and functional properties of fermented foods.