降解温和气单胞菌AHLs乳酸菌的筛选及在三文鱼保鲜中的应用

从传统发酵食品中筛选对温和气单胞菌（Aeromonas sobria）N-酰基高丝氨酸内酯（N-acyl-homoserine lactones,AHLs）信号分子具有降解活性的乳酸菌，对其进行菌种鉴定，探究乳酸菌产生的群体感应淬灭作用酶存在位置与类型。以三文鱼为载体，通过测定细菌菌落总数、持水力、硫代巴比妥酸（thiobarbituric acid,TBA）值以及挥发性盐基氮（total volatile basic nitrogen,TVB-N）值等指标评价乳酸菌抑制温和气单胞菌致腐能力的效果。结果表明：采用96孔板法结合牛津杯法筛选获得1株对温和气单胞菌AHLs降解活性接近100%的菌株YF-8，经鉴定为戊糖片球菌（Pediococcus pentosaceus）。菌株YF-8淬灭酶存在于胞外上清液中，且在酸性、中性条件下均具有降解活性，初步判定为AHLs酰基转移酶。通过生长曲线确定YF-8淬灭酶粗提物在亚抑菌质量浓度2.0、4.0 mg/mL和6.0 mg/mL时不影响温和气单胞菌生长。此外，感染温和气单胞菌的三文鱼经YF-8淬灭酶粗提物处理过后，细菌菌落总数、持水力、TBA值...

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-8 quenching 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.