Inoculated fermentation enables rapid fermentation of aquatic products. No studies have been conducted on the lipid profiles of inoculated fermented golden pompano (Trachinotus ovatus). In this study, a lipase-producing Bacillus subtilis with salt tolerance was screened from traditionally fermented golden pompano (TF) and used as a starter culture. Whole-genome sequencing analysis revealed it carries four CRISPR structures and two genes encoding triacylglycerol lipase. Untargeted lipidomics identified lipid molecules (833) in six major classes from B. subtilis SCSMX-2 fermented golden pompano (IF). Twenty-eight lipid molecules were upregulated in IF, including phosphatidylcholines (PCs), triacylglycerols (TAGs), and lysophosphatidylcholine. B. subtilis supplementation enhanced the production of polyenyl phosphatidylcholines and medium- and long-chain triacylglycerols. The IF rich in linoleic, docosahexaenoic acids, and eicosapentaenoic acid were primarily distributed in the sn-2 position of DHA, PC and PE. This research revealed the lipid profiles of IF, providing theoretical basis for the application of B. subtilis in the fermented fish industry.

Popular fermented golden pomfret (Trachinotus ovatus) is prepared via spontaneous fermentation; however, the mechanisms underlying the regulation of its flavor development remain unclear. This study shows the roles of the complex microbiota and the dynamic changes in microbial community and flavor compounds during fish fermentation. Single-molecule real-time sequencing and molecular networking analysis revealed the correlations among different microbial genera and the relationships between microbial taxa and volatile compounds. Mechanisms underlying flavor development were also elucidated via KEGG based functional annotations. Clostridium, Shewanella, and Staphylococcus were the dominant microbial genera. Forty-nine volatile compounds were detected in the fermented fish samples, with thirteen identified as characteristic volatile compounds (ROAV > 1). Volatile profiles resulted from the interactions among the microorganisms and derived enzymes, with the main metabolic pathways being amino acid biosynthesis/metabolism, carbon metabolism, and glycolysis/gluconeogenesis. This study demonstrated the approaches for distinguishing key microbiota associated with volatile compounds and monitoring the industrial production of high-quality fermented fish products.