Screening of Lactic Acid Bacteria Degrading N-Acyl-homoserine Lactones from Aeromonas sobria and Its Application in Salmon Preservation

In this study, lactic acid bacteria (LAB) capable of degrading N-acyl-homoserine lactones (AHLs) signal molecules from Aeromonas sobria were screened from traditional fermented foods and identified. The locations and types of LAB quorum quenching enzymes were explored. The salmon spoilage ability of LAB was evaluated by measuring total bacterial count, water-holding capacity, thiobarbituric acid (TBA) value and total volatile basic nitrogen (TVB-N) content. The results showed that a strain capable of degrading almost 100% of A. sobria-derived AHLs, named as YF-8, was obtained using the 96-well plate method combined with the Oxford cup method. It was identified as Pediococcus pentosaceus. The quorum quenching enzyme of strain YF-8 existed in the extracellular supernatant and had AHL degradation activity under both acidic and neutral conditions. It was preliminarily identified as AHLs-acyltransferase. The crude extract of YF-8quenching enzyme did not affect the growth of A. sobria at sub-inhibitory concentrations of 2.0, 4.0 and 6.0 mg/mL. In addition, the crude extract could maintain the total bacterial count, water-holding capacity, TBA value and TVB-N value of salmon infected with A. sobria during storage. The results of this study are expected to provide a theoretical basis for the screening of microbial quorum sensing quenchers and aquatic product biopreservatives.