Novel perspective on the spoilage metabolism of refrigerated sturgeon fillets: Nonspecific spoilage dominant organisms play an important role

Aeromonas sobria, a specific spoilage organism (SSO) in refrigerated (4 degrees C) sturgeon fillets, is considered as the main contributor for sturgeon spoilage. However, the spoilage metabolism of A. sobria is influenced by bacterial interactions, and the effect of nonspecific spoilage dominant organisms on the spoilage metabolism of A. sobria during storage is still unknown. In this study, the spoilage characteristics and metabolite changes of different inoculation groups under chilled storage were investigated through a co-cultivation model. The results of spoilage indicators indicated that the microbial interactions changed the spoilage characteristic of the fish model, although A. sobria played the most important role. Based on metabolome results, 549 differential metabolites were identified in two ion modes, which involved 9 chemical categories and 4 main metabolic pathways. The nonspecific spoilage dominant bacteria M. caseolyticus in the early stage of refrigeration affects the amino acid metabolism pathways of fish model by secreting extracellular proteases and peptidases. However, the nonspecific spoilage dominant bacteria A. albensis in the later period of refrigeration accelerate the lipid metabolism, and amino acid metabolism via secreting extracellular peptidases, lipase and esterase. This work may provide insights on controlling the spoilage of aquatic products by intervening degradation pathways.