A Deep-Sea probiotic platform: Dual-function biopreservation for aquaculture immunomodulation and meat shelf-life extension

Two major challenges in the food industry include antibiotic overuse in aquaculture and reliance on synthetic preservatives to increase meat shelf-life. To address these challenges, we developed a dual-function platform using Lactococcus lactis L25_4, isolated from 312-m depth in Taiwan's Taimali region. As a feed additive, L. lactis L25_4 significantly enhanced Litopenaeus vannamei (whiteleg shrimp) survival against Vibrio vulnificus infection by modulating gut microbiota (e.g., enriching Rhodobacteraceae and Streptococcaceae and inhibiting Desulfovibrionaceae and Klebsiella) and improving gut membrane integrity. It also upregulated immune genes (e.g., HSP70, Lysozyme C, SOD and Tollo) and increased short chain fatty acids (SCFAs) levels in the shrimp intestinal region. Transcriptomic and microbiome analyses revealed immune priming and stress mitigation, with Spearman correlations linking beneficial bacteria to enhanced gut integrity and immune activation. The cell-free supernatant (CFS) of L. lactis L25_4 was incorporated into a chitosan-based hydrogel and applied as a surface coating on raw pork meat. Samples were inoculated with Shewanella putrefaciens (10⁶ CFU/mL), a known meat spoilage bacterium, and the CFS–chitosan hydrogel inhibited bacterial growth by >99 % for up to 5 days at 4 °C compared to untreated controls, as confirmed by CFU enumeration and Cryo-SEM imaging. L. lactis L25_4 demonstrated functional stability across aquaculture and chilled meat systems, supporting its dual application in biopreservation. By integrating multi-omics, biopolymer engineering, and pathogen inhibition assays, we present a scalable, nature-derived alternative to antibiotics and synthetic preservatives. This work advanced food science via a validated, application-ready platform aligned with One Health principles and offers a paradigm shift in sustainable biopreservation technologies.