Specific spoilage bacteria in cold chain logistics: A study on ATP-related compounds degradation in large yellow croaker ( Larimichthys crocea )

This study evaluated the contribution of three spoilage bacteria ( Shewanella putrefaciens ( S . putrefaciens ), Pseudomonas fluorescens ( P. fluorescens ), and Aeromonas salmonicida ( A . salmonicida )) to the degradation of adenosine triphosphate (ATP)-related compounds in fish juice and fillet systems of large yellow croaker during cold chain logistics. The contribution of spoilage bacteria was explored by determining the microbial counts, ATP-related compounds, and associated enzyme activities. The results revealed that the S . putrefaciens , P. fluorescens , and A . salmonicida have the highest activities in 5 '-nucleotidase (5 '-NT), acid phosphatase (ACP), and alkaline phosphatase (AKP), with 49.78, 162.24, and 142.3 U/gprot, respectively. The rapid degradation of inosine monophosphate (IMP) occurs with increasing 5 '-NT activity. It indicates that S . putrefaciens , P. fluorescens , and A . salmonicida mainly secreted 5 '-NT, ACP, and AKP to degrade IMP, respectively, and that 5 '-NT was the key enzyme in degrading IMP. All three are notable producers of purine nucleoside phosphorylase (PNP) and xanthine oxidase (XOD). The results showed that S . putrefaciens is the primary bacterium in the pre-degradation phase of ATP-related compounds, and A . salmonicida presumably dominates in the post-degradation phase. This study offers critical insights into the research on spoilage mechanisms of marine fish throughout the cold chain logistics.