低温等离子体处理模式对冷藏南美白对虾中假单胞菌的抑菌效果及机理研究

摘 要：目的 探究低温等离子体(cold plasma, CP)处理模式对冷藏南美白对虾中常见荧光假单胞菌(Pseudomonas fluorescens)的抑菌效果及其作用机制。方法 通过CP直接处理和循环处理P. fluorescens,研究了两种处理模式下臭氧含量动态变化对P. fluorescens的生长曲线、细胞活力,生物膜形成、细胞壁、细胞膜完整性和南美白对虾菌落总数及假单胞菌数等指标的影响。结果 两种处理模式在CP处理3 min或3 cycles后,包装内臭氧含量达到最高值,分别为(850±10) mg/m3和(874±20) mg/m3。CP循环处理模式使得臭氧含量随处理循环数递增,因此获得更长的臭氧存在时间从而具有更大的抑菌能力。P. fluorescens生长曲线表明CP处理使得菌体延迟期变长且对数生长期推迟。此外,CP处理后的P. fluorescens细胞活力显著下降(P<0.05),CP-1 min,CP-3 min和CP-3 cycles组的细胞活力分别为33.03%、5.90%和4.82%。同时相比CP-3 min组,CP-3 cycles组的P. fluorescens生物膜OD值下降27.61%。碱性磷酸酶(alkaline phosphatase, AKP)活性和核酸蛋白泄漏量结果表明,细胞壁和细胞膜完整性受损可能是P. fluorescens失活的直接原因。对虾保鲜测试结果证实,贮藏第6 d,CP-3 cycles组虾体中的菌落总数和假单胞菌数相比CP-3 min组分别降低了58.02%和79.54%。结论 CP循环处理模式通过延长对臭氧与对虾的暴露时间,提高了对P. fluorescens的灭活效果,同时还具有更优越的保鲜能力。本研究为开发基于CP技术的新型保鲜技术应用提供了理论参考。 关键词：低温等离子体;荧光假单胞菌;抑菌机制;保鲜

Study on the antibacterial effect and mechanism of cold plasma treatment modes on Pseudomonas fluorescens in refrigerated Penaeus vannamei

ABSTRACT: Objective To explore the antibacterial effect and mechanism of cold plasma (CP) treatment modes on Pseudomonas fluorescens, which is common in aquatic products. Methods In this experiment, P. fluorescens was treated by CP direct treatment and cyclic treatment. The effects of dynamic changes of ozone content in two treatment modes on the growth curve, cell viability, biofilm formation, cell wall, cell membrane integrity of P. fluorescens, the total viable count and Pseudomonas count of Penaeus vannamei were studied. Results The results showed that the ozone content in the packaging reached the highest value of (850±10) mg/m3 and (874±20) mg/m3 after 3 min or 3 cycles of CP treatment, respectively. The CP cyclic treatment mode allowed the ozone content to increase with the number of treatment cycles, thus obtaining a longer ozone lifetime and thus having a greater antibacterial ability. The growth curve of P. fluorescens showed that CP treatment prolonged the lag phase and delayed the logarithmic growth phase. In addition, the cell viability of P. fluorescens after CP treatment was significantly (P<0.05) decreased, and the cell viability of CP-1 min, CP-3 min and CP-3 cycles groups was 33.03%, 5.90% and 4.82%, respectively. Meanwhile, compared with CP-3 min group, the OD value of P. fluorescens biofilm in CP-3 cycles group decreased by 27.61%. The results of alkaline phosphatase (AKP) activity, nucleic acid and protein leakage showed that the damage of cell wall and membrane integrity may be the direct cause of P. fluorescens inactivation. The results of shrimp preservation test confirmed that on the 6 th day of storage, the CP-3 cycles group reduced the total viable count in the shrimp by 58.02% and the Pseudomonas count by 79.54% compared with the CP-3 min group. Conclusion The CP cyclic treatment mode, by prolonging the exposure time to ozone and shrimp, enhanced the inactivation effect on P. fluorescens while exhibiting superior freshness preservation capabilities. This study provides a theoretical reference for the development of new preservation technology based on CP technology. KEY WORDS: Cold plasma; Pseudomonas fluorescens; Antibacterial mechanism; Preservation