冷却猪肉及托盘表面细菌生物被膜分析和肉源荧光假单胞菌的鉴定与被膜研究

Biofilm-Forming Ability of Bacteria from Chilled Pork and Tray Surfaces and Biofilm Characteristics of Meat-Related Pseudomonas fluorescens

为研究冷却猪肉及其接触面中细菌生物被膜能力并探讨肉类特定腐败菌的生物被膜特征,分析了腐败的冷却肉和销售托盘表面的细菌生物被膜形成能力;利用形态学观察、16S r DNA分析和VITEK2微生物鉴定系统鉴定了冷却肉中一株生物被膜能力较强的荧光假单胞菌(Pseudomonas fluorescens);测定了该菌在培养基和猪肉浸提液中的生物被膜能力;用激光共聚焦和扫描电子显微镜观测了其生物被膜的结构特征。结果发现:冷却肉中及其销售托盘表面的细菌能够形成生物被膜的比例较高,37%和45%的细菌具有较强生物被膜形成能力。肉源性荧光假单胞菌能够在培养基和肉液中形成大量生物被膜,具有较强的生物被膜能力。显微成像结果表明荧光假单胞菌在培养6 h后有明显黏附,18 h后多糖分泌增多、菌体堆积并形成具有生物功能的立体生物被膜。这些特点可能有利于荧光假单胞菌在冷却肉表面黏附并成为优势腐败菌。

The biofilm-forming ability of bacteria in chilled pork and on tray surfaces, and the biofilm characteristics of specific spoilage bacteria in meat were analyzed. One strain in chilled meat with a strong biofilm-forming ability was identified as Pseudomonas fluorescens by morphological observation, 16 S r DNA sequence analysis, and a VITEK2 microbial identification system. The biofilm-forming ability of this meat-related specific spoilage bacterium was measured in tryptic soy broth（TSB） and pork extract. Additionally, the structural characteristics of biofilms were evaluated by confocal laser scanning microscopy and scanning electron microscopy. A high percentage of the bacteria in chilled pork and on tray surfaces were capable of forming biofilms, and 37% and 45% of bacteria from chilled pork and tray surfaces showed strong biofilm-forming abilities, respectively. Pseudomonas fluorescens formed large amounts of biofilm in both TSB culture and pork extract. The microscopic imaging results showed an apparent adhesion of Pseudomonas fluorescens after six hours of culture, and increasing polysaccharide secretion, bacterial accumulation, and formation of three-dimensional biofilms with biological function were observed after 18 hours. These features may be beneficial for the meat-related Pseudomonas fluorescens to adhere to chilled meat surfaces and become the dominant spoilage bacteria.