藤椒精油对腐败解淀粉芽孢杆菌DY1a生物被膜的抑制作用

【背景】芽孢杆菌是豆制品的重要腐败菌，在气液界面形成生物膜，对产品生产带来持续污染。【目的】探讨藤椒精油(Zanthoxylum armatum DC.essential oil,ZA-EO)对腐败解淀粉芽孢杆菌DY1a菌体及生物被膜的抑制作用与机制。【方法】采用气相色谱-质谱(gas chromatography-mass spectrometer,GC-MS)分析藤椒精油主要成分与相对含量，通过二倍稀释法测定藤椒精油对菌株的最低抑菌浓度(minimum inhibitory concentration,MIC)和最低杀菌浓度(minimum bactericidal concentration,MBC)，并分析精油对腐败菌胞外蛋白酶活性、腐败菌生物被膜形成抑制及成熟生物被膜的清除作用，采用扫描电镜结合三维光学显微镜分析生物被膜形貌结构变化，测定生物被膜胞外聚合物(extracellular polymeric substance,EPS)多糖与蛋白质含量变化；并通过细菌运动能力、细胞黏附及自聚集能力、细胞表面疏水性和Zeta电位来初步探讨藤椒精油对生物被膜的抑制机理。【结果】藤椒精...

Antibiofilm effect of Zanthoxylum armatum DC. essential oil against spoilage Bacillus amyloliquefaciens DY1a

Background] Bacillus spp. are major aerobic bacteria associated with the spoilage of soy products. They form biofilms at the air-liquid interface to bring about constant microbial contamination to soy food processing line. Objective] To examine the activity of Zanthoxylum armatum DC. essential oil (ZA-EO) against the growth and biofilm formation of a spoilage bacterium Bacillus amyloliquefaciens DY1a isolated from soy products. Methods] Gas chromatography-mass spectrometry (GC-MS) was used for the chemical characterization of ZA-EO. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of ZA-EO against DY1a were determined by the microdilution method. The inhibitory effect on extracellular protease activity and biofilm formation and the eradication of preformed biofilm by ZA-EO were evaluated. Scanning electron microscope coupled with 3D optical microscope was used to observe the surface topography and structure changes of the biofilm treated with ZA-EO. Besides, the content of exopolysaccharide and protein in the extracellular polymeric substance (EPS) were measured. The anti-biofilm mechanism of ZA-EO was explored from swimming and swarming motility, cell adhesion and auto-aggregation, cell surface hydrophobicity, and Zeta potential. Results] ZA-EO mainly contained linalool (52.37%), D-limonene (21.81%), and sabinene (10.94%). The MIC and MBC of ZA-EO against spoilage B.amyloliquefaciens DY1a were 3.2 µL/mL and 12.8 µL/mL, respectively. Additionally, 3.2 µL/mL ZA-EO inhibited the secretion of extracellular protease and the biofilm formation, and showed the eradication efficiency of 25.79% for the preformed biofilm. Moreover, ZA-EO decreased the thickness and surface roughness of the biofilm as well as the content of exopolysaccharide and protein in EPS. Furthermore, ZA-EO treatment significantly weakened the swimming and swarming motility, inhibited cell adhension and auto-aggregation, enhanced the cell surface hydrophobicity, and reduced the surface charge of DY1a. Conclusion] ZA-EO had activity against the growth and biofilm formation of B.amyloliquefaciens DY1a and exhibited promising eradication of preformed biofilm. The activity ofZA-EO against the biofilm formation of B.amyloliquefaciens can be attributed to the interruption against cell motility, changing of cell surface characteristics, and inhibition on cell adhension and auto-aggregation during the early stage, as well as the reduction of exopolysaccharide and protein content in EPS.