Identification of dominant spoilage bacteria, bacterial diversity analysis, and antibacterial exploration of chilled monkfish

Abstract

In this study, we aimed to investigate spoilage bacteria in monkfish stored under vacuum and aerobic (air) refrigeration at 4 °C for the first time. In vitro bacterial cultures, coupled with Sanger sequencing of genes, were used to isolate and identify 21 and 31 bacterial strains from vacuum-packed and aerobically packed monkfish, respectively. The isolated strains were back-inoculated into sterile fish blocks and inactivated fish juice. Our findings revealed that Carnobacterium, Shewanella, Vagococcus, Myroides, and Psychrobacter increased the production of total volatile base nitrogen (TVB-N) and trimethylamine (TMA) from monkfish. Monkfish showed a decrease in bacterial flora diversity with storage time, the emergence of dominant species during the spoilage process, and differences in bacterial growth tolerance in different packaging forms, resulting in variability in bacterial community structure. Shewanella accelerated the spoilage of monkfish in both packaging forms. Vagococcus and Psychrobacter were numerically dominant in both storage forms. Unlike some spoilage bacteria in refrigerated fish, Carnobacterium (11.72%) and Myroides (9.01%) were the specific spoilage bacteria in vacuum and aerobic storage at 4 °C, respectively. Furthermore, a combination of nisin (NS), ε-polylysine (ε-PL), and citric acid (CA) significantly reduced the survival rate of dominant spoilage bacteria and the total viable bacterial count in monkfish.