Co-encapsulation of Lactiplantibacillus plantarum and Clostridium tyrobutyricum in gelatin-xylan microcapsules for high-yield butyric acid production: Preparation and in vitro assessment

Butyric acid, a key biomarker of intestinal health, can be efficiently synthesized through a synergistic fermentation system utilizing xylan as a substrate and a co-culture of Lactiplantibacillus plantarum and Clostridium tyrobutyricum. In this study, we developed a novel gelatin–xylan-based probiotic microcapsule delivery system to enhance probiotic stability and butyric acid production. The system was fabricated via Maillard reaction-mediated conjugation followed by spray drying. Physicochemical characterization confirmed that the microcapsules exhibited a uniform particle size distribution and stable surface charge properties. Importantly, gelatin–xylan encapsulation significantly improved the storage stability and survival of L. plantarum and C. tyrobutyricum, maintaining a viable bacterial count of 7 log CFU/mL after 4 h of simulated gastrointestinal digestion. Furthermore, in vitro fecal fermentation showed that the co-encapsulation system produced 0.92 g/L butyric acid, which was 6.57-fold higher than that of the non-encapsulated group. Microbial community analysis further revealed that the formulation selectively enriched beneficial genera, including Lactobacillus, Clostridium, Bifidobacterium, and Sutterella. Collectively, these findings highlight the dual functionality of the engineered microcapsules in enhancing butyric acid production and modulating gut microbial composition.