蜡样芽孢杆菌YF-2对荧光假单胞菌群体感应的淬灭活性

The Quorum Sensing's Quenching Activity of Bacillus cereus YF-2 to Pseudomonas fluorescens

荧光假单胞菌是生鲜水产品中常见的优势腐败菌,其致腐能力受N-酰基高丝氨酸内酯(AHLs)类群体感应系统调控。以群体感应淬灭活性为导向,利用热灭活和酸敏感试验分析菌株YF-2分泌的淬灭活性物质类型。采用结晶紫染色法和激光共聚焦显微镜技术探究菌株YF-2对荧光假单胞菌生物膜的抑制和清除作用。通过生理生化和16S rDNA对菌株YF-2进行鉴定。结果表明:菌株YF-2对荧光假单胞菌AHLs具有较强的淬灭作用,降解率为100%,且淬灭活性物质在细胞提取物(CCE)中,通过热灭活及酸敏感试验初步判断淬灭活性物质为酰基转移酶或氧化还原酶。蛋白质量浓度为20,40μg/mL和80μg/mL的CCE对C4-HSL、C6-HSL及C8-HSL的降解率在52.8%~100%范围,对荧光假单胞菌生物膜的抑制率和清除率分别在25.84%~56.63%和26.12%~59.35%范围。此外,激光共聚焦图像表明CCE使荧光假单胞菌生物膜厚度减少,生物膜结构被破坏。同时,菌株YF-2被鉴定为蜡样芽孢杆菌。本研究为应用芽孢杆菌控制水产品腐败菌荧光假单胞菌提供一定的理论依据。

Pseudomonas fluorescens is a dominant spoilage bacterium commonly found in fresh aquatic products,and its spoilage ability is regulated by a quorum-sensing system of N-homoserine lactones(AHLs).Based on the quorum-sensing quenching activity,the type of quenching activity substance from strain YF-2 was analyzed using heat inactivation and acid sensitivity tests.The results showed that strain YF-2 had a significant quenching effect on P.fluorescens AHLs,with a degradation rate of 100%.Its quenching active substance existed in the crude cell extract(CCE),which was preliminarily identified as acyltransferase or oxidoreductase by heat inactivation and acid sensitivity assays.The degradation of C4-HSL,C6-HSL and C8-HSL treated by the CCE at protein concentrations of 20,40μg/mL and 80μg/mL ranged from 52.8%to 100%,and the inhibition and clearance rate of P.fluorescens biofilms ranged from 25.84%to 56.63%and 26.12%to 59.35%,respectively.In addition,the confocal laser scanning microscopy showed that the CCE reduced the thickness of P.fluorescens biofilm and disrupted the biofilm structure.Meanwhile,Bacillus cereus was recognized as the source of strain YF-2.The application of B.cereus to control the spoilage bacterium P.fluorescens in aquatic goods will have a theoretical foundation thanks to this study.