Metabolic profiling, antibacterial effects, and preservation mechanisms of Paenibacillus provencensis metabolites in refrigerated Sea Bass (Perca fluviatilis)

This study proposed to investigate the inhibition mechanism of the Paenibacillus provencensis (PP-2) metabolites on the dominant spoilage bacteria of sea bass and the application in preservation. Shewanella (71.11 %) and Pseudomonas (13.54 %) were the main genera. The Shewanella putrefaciens (L-1) and Pseudomonas fragi (L-4) were isolated and purified based on spoilage factors as dominant spoilage bacteria. PP-2 supernatant metabolites at minimum inhibitory concentration (MIC, 150 mg/mL) inhibited L-1 and L-4 by more than 95 % with significant antioxidant properties. The PP-2 metabolites were detected by LC-MS mainly including organic acids and derivatives, lipids molecules, organic heterocyclic compounds, and organic oxides. According to the transmission electron microscope (TEM) results, Additionally, the metabolites demonstrated antioxidant properties and disrupted bacterial cell membranes, highlighting their potential for controlling seafood spoilage. PP-2 metabolites significantly lowered pH ( p  < 0.05), TBARS values (0.33 ± 0.01 μmol/g), and TVB-N levels (24.06 ± 2.25 mg/100 g) compared to Nisin-treated and control groups after 6–8 d. After 8 d, colony counts in the PP-2 group (7.90 ± 0.01 log CFU/g) remained below the spoilage threshold. PP-2 metabolites also reduced protein oxidation, with carbonyl content at 0.33 ± 0.01 μmol/g and sulfhydryl content at 5.26 ± 0.18 μmol/g. The metabolites preserved textural properties, showing slower declines in hardness, elasticity, and chewiness, and lower juice leakage (9.37 ± 1.27 %). Metabolomic analysis revealed that PP-2 metabolites disrupted several key bacterial metabolic pathways, leading to bacterial death. These results suggest that PP-2 metabolites enhance seafood preservation by targeting bacterial metabolic processes.