面包乳杆菌ZHG2-1对荧光假单胞菌群体感应的淬灭作用

Quorum Quenching Effects of Lactobacillus crustorum ZHG2-1 on Pseudomonas fluorescens

以紫色杆菌CV026为指示菌株,验证面包乳杆菌ZHG2-1群体感应淬灭活性,检测其对荧光假单胞菌生物膜、致腐因子表型以及相关基因表达水平的影响,探究面包乳杆菌ZHG2-1对荧光假单胞菌群体感应的淬灭机制。结果表明:菌株ZHG2-1无细胞上清液对荧光假单胞菌AHLs的降解活性为100%。在亚抑制质量浓度(1.0,2.0,3.0 mg/mL)下,菌株ZHG2-1粗提物对荧光假单胞菌生物膜的抑制率和清除率分别为在9.66%~31.32%和28.62%~62.82%范围,对胞外多糖、蛋白酶、脂肪酶、生物胺等致腐因子抑制率在7.23%~100%范围,并呈质量浓度依赖性。扫描电镜结果表明亚抑制质量浓度的菌株ZHG2-1粗提物处理使其生物膜量显著减少,细菌菌落处于分散状态。qRT-PCR结果显示,菌株ZHG2-1粗提物对荧光假单胞菌群体感应基因rhlI和rhlR分别下调0.93和0.99,aprX、algA、orm、flgA、ldcA等生物膜和致腐基因的表达水平也被显著抑制,说明面包乳杆菌ZHG2-1通过干扰荧光假单胞菌群体感应基因的表达,影响其生物膜和腐败因子的产生。本研究结果为开发水产品新型生物防腐剂提供理论依据。

In this study,quorum-sensing quenching activity of Lactobacillus crustorum ZHG2-1 was verified with the Chromobacterium violaceum CV026 as a indicator strain.Based on the change of biofilm,phenotypes of spoilage factors and the expression levels of related genes,the quorum sensing quenching mechanism of Lb.crustorum ZHG2-1 on P.fluorescens was detected.The results showed that the degradation rate of cell-free supernatant from strain ZHG2-1 to P.fluorescens AHLs reached 100%.The sub-inhibitory concentration(1.0,2.0,3.0 mg/mL)of strain ZHG2-1 crude extract could inhibit and remove the biofilm of P.fluorescens,and the inhibition rate and clearance rate reached 9.66%-31.32%and 28.62%-62.82%,respectively.In addition,the inhibition rate of strain ZHG2-1 crude extract with sub-inhibitory concentration on P.fluorescens spoilage factors(exopolysaccharides,proteases,lipases,biogenic amines)reached 7.23%-100%.Meanwhile,the inhibition rate was mass concentration-dependent.Scanning electron microscope showed that the sub-inhibitory concentration of strain ZHG2-1 crude extract treatment significantly reduced the amount of biofilm and the bacterial colonies were in a dispersed state.The results of qRT-PCR showed that the crude extract of strain ZHG2-1down-regulated the quorum-sensing genes rhlI and rhlR of P.fluorescens by 0.93 and 0.99,respectively,and the expression levels of aprX,algA,orm,flgA,ldcA and other biofilm and spoilage genes was significantly inhibited.The results indicated that Lb.crustorum interfered with the expression of quorum-sensing genes of P.fluorescens,thereby affecting the production of biofilm and spoilage factors.