Dykes G A, Sampathkumar B, Korber D R
Department of Applied Microbiology and Food Science, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK, Canada S7N 5A8.
Int J Food Microbiol. 2003 Dec 15;89(1):1-10. doi: 10.1016/s0168-1605(03)00123-5.
The effect of planktonic or biofilm modes of growth on survival, hydrophobicity and cellular protein expression patterns of a pathogenic Campylobacter jejuni strain were determined. This was achieved by growing the strain in brain heart infusion broth (with 1% yeast extract), or attached to glass beads in the same medium, at 37 degrees C for 48 h under microaerophilic conditions. Cells from the broth or the bead surfaces were stored at different temperatures (4, 10, 25 and 37 degrees C) for 28 days in phosphate buffered saline (PBS) and monitored at appropriate time intervals for culturable numbers and hydrophobicity by standard methods. In addition, cells were inoculated onto the surface of two processed meat products (a bologna and a summer sausage) vacuum packaged and stored at 4 degrees C for 28 days. Numbers of culturable cells were monitored at appropriate time intervals by standard methods. Cells from the broth or the bead surfaces were also examined for protein expression using two-dimensional protein electrophoresis. Results indicated that numbers of culturable cells in phosphate buffered saline decreased from approximately 6 log colony forming units (cfu) g(-1) to undetectable levels within 14-day storage in a temperature dependent manner. Hydrophobicity of broth grown cells decreased from 15% to 0% adherence to xylene over the same time in a temperature independent manner. Cells grown in a biofilm mode initially displayed a <0.3% adherence to xylene which was maintained during storage. Furthermore, cells grown in the biofilm mode decreased in number more rapidly on storage in buffer than their counterparts grown in broth. Numbers of culturable cells on meat decreased from approximately 5 log cfu g(-1) to undetectable levels within 14-day storage in a product dependent manner, with the most rapid decrease observed for the more acidic summer sausage. Cells grown in a biofilm mode decreased in number more rapidly on storage than broth grown cells. The protein expression patterns differed between planktonic and biofilm cells with seven unique and 12 up-regulated protein spots expressed in a growth mode specific manner. A number of the differentially expressed spots were tentatively identified, by comparison to existing literature, as surface- and stress-associated proteins. Despite the elicitation of some putative stress proteins, this study importantly indicates that biofilm cells of C. jejuni are less resistant to stress than their planktonic counterparts and may lack a sophisticated adaptive stress-resistance response. These findings have implication in determining the risks of infection associated with C. jejuni contamination on food.
研究了空肠弯曲菌致病菌株的浮游生长模式或生物膜生长模式对其存活、疏水性和细胞蛋白质表达模式的影响。具体做法是，将该菌株在脑心浸液肉汤（含1%酵母提取物）中培养，或在相同培养基中附着于玻璃珠上，于37℃、微需氧条件下培养48小时。将肉汤或珠表面的细胞在磷酸盐缓冲盐水（PBS）中于不同温度（4、10、25和37℃）下保存28天，并通过标准方法在适当时间间隔监测其可培养数量和疏水性。此外，将细胞接种到两种加工肉类产品（一种大红肠和一种夏季香肠）表面，真空包装后于4℃保存28天。通过标准方法在适当时间间隔监测可培养细胞的数量。还使用二维蛋白质电泳对肉汤或珠表面的细胞进行蛋白质表达检测。结果表明，磷酸盐缓冲盐水中可培养细胞的数量在14天的储存期内以温度依赖的方式从约6 log菌落形成单位（cfu）g-1降至检测不到的水平。肉汤中生长的细胞的疏水性在同一时间内以与温度无关的方式从15%对二甲苯粘附率降至0%。以生物膜模式生长的细胞最初对二甲苯的粘附率<0.3%，在储存期间保持不变。此外，以生物膜模式生长的细胞在缓冲液中储存时数量减少得比在肉汤中生长的细胞更快。肉类上可培养细胞的数量在14天的储存期内以产品依赖的方式从约5 log cfu g-1降至检测不到的水平，酸性更强的夏季香肠数量减少最快。以生物膜模式生长的细胞在储存时数量减少得比在肉汤中生长的细胞更快。浮游细胞和生物膜细胞的蛋白质表达模式不同，有7个独特的和12个上调蛋白质斑点以生长模式特异性方式表达。通过与现有文献比较，初步鉴定了一些差异表达斑点为表面相关蛋白和应激相关蛋白。尽管诱导了一些假定的应激蛋白，但本研究重要地表明，空肠弯曲菌的生物膜细胞比其浮游对应细胞对应激的抵抗力更弱，可能缺乏复杂的适应性应激抗性反应。这些发现对于确定与空肠弯曲菌污染食品相关的感染风险具有重要意义。
