Multi-omic profiling reveals the impact of keratinase kerZJ on mouse gut homeostasis.

Keratinase kerZJ is a multifunctional protease with potential as a feed additive and functional ingredient. Here we performed an integrated multi‑omics evaluation of its biosafety and impact on gut homeostasis in mice. Our findings confirm that kerZJ is well-tolerated, with no evidence of systemic toxicity or intestinal epithelial damage. Integrated transcriptomic and proteomic analyses revealed that kerZJ reinforces intestinal barrier integrity by upregulating extracellular matrix components, including collagen IV, and modulates mucosal immunity by enhancing B-cell activation and antimicrobial peptide defenses without inducing inflammation. Furthermore, kerZJ administration led to a significant upregulation of digestive enzymes and a dose-dependent increase in short-chain fatty acids production. Microbiome analysis showed that while high-dose kerZJ altered community composition, it enriched for beneficial taxa like Lactobacillaceae and did not induce dysbiosis. These results demonstrate that kerZJ safely enhances gut barrier function, promotes a favorable immune and metabolic environment, and fosters a resilient gut ecosystem, supporting its development as a safe feed additive and nutraceutical component.