Insights into the molecular mechanisms of lipid transformation in sturgeon fillets: Interplay between specific spoilage and dominant bacteria

This study investigates spoilage bacteria's impact on lipid metabolism in sturgeon fillets using UHPLC-Q-Orbitrap-MS/MS-based untargeted lipidomic analysis. A total of 4041 lipid molecules across five classes and 42 subclasses were identified, including glycerophospholipids (GPs, 50.88%), glycerolipids (GLs, 36.08%), sphingolipids (SPs, 10.47%), fatty acyls (FAs, 2.45%), and sterol lipids (STs, 0.12%). <i>Aeromonas sobria</i>, a specific spoilage bacterium, reduced GPs and FAs while increasing GLs, SPs, and STs via extracellular lipases and esterases. <i>Acinetobacter albensis</i>, the dominant bacterium, mainly elevated SPs and FAs. Their interaction promoted lipid metabolism and oxidation while producing volatile organic compounds (VOCs). Ethyl isobutyrate, ethyl propionate, isobutyl formate, pentan-2-one, propan-2-one, 2-butanone, 3-methyl-3-buten-1-ol, and dimethyl sulfide were mainly associated with <i>Acinetobacter albensis</i>, while 1-hexanol, 1-pentanol, 1-penten-3-ol, 1-hydroxypropan-2-one, 3-methyl-1-butanol, 2-methylbutanal, 3-hydroxy-2-butanone, and propionaldehyde were mainly related to <i>Aeromonas sobria</i>. This work unveils the mechanism of lipid transformation in sturgeon fillets during refrigerated storage, offering insights for aquatic products quality control.