Brocklehurst T F, Mitchell G A, Ridge Y P, Seale R, Smith A C
Institute of Food Research, Norwich Laboratory, Colney, UK.
Int J Food Microbiol. 1995 Sep;27(1):45-60. doi: 10.1016/0168-1605(94)00152-v.
The growth of colonies of Salmonella typhimurium derived from single immobilised cells was studied while subjected to constant and sinusoidally-varying temperatures. The bacteria grew in microbiological culture media adjusted to different pH and sodium chloride (NaCl) concentration and solidified with gelatin that was contained within a cassette formed between sheets of PVC film that allowed gaseous exchange. At pH 7.0 and 0.5% (w/v) NaCl and either 12 degrees C or 20 degrees C, S. typhimurium grew at a rate similar to that in liquid medium. The decrease in growth rate at 20 degrees C at a lower pH or higher NaCl concentration was greater in the case of immobilised cells than for cells in liquid medium. The change in the numbers of viable bacteria was measured with time under sinusoidally-varying temperatures between 4 and 22 degrees C and between 12 and 22 degrees C of period in the range 12 to 480 min. The experimental growth curves were compared with predictions based on isothermal growth in liquid medium. The discrepancies between experiment and prediction were greater for gels stressed by NaCl or pH than for gels at pH 7.0 and containing 0.5% (w/v) NaCl, consistent with the isothermal observations.
对源自单个固定化细胞的鼠伤寒沙门氏菌菌落生长情况进行了研究，研究过程中使其处于恒定温度和正弦变化的温度环境下。细菌在调整至不同pH值和氯化钠（NaCl）浓度的微生物培养基中生长，培养基用明胶固化，明胶置于两片允许气体交换的PVC薄膜之间形成的盒中。在pH值为7.0、NaCl浓度为0.5%（w/v）且温度为12℃或20℃时，鼠伤寒沙门氏菌的生长速率与在液体培养基中的生长速率相似。在较低pH值或较高NaCl浓度下，20℃时固定化细胞的生长速率下降幅度比液体培养基中的细胞更大。在温度在4至22℃之间以及温度在12至22℃之间呈正弦变化、周期在12至480分钟范围内的情况下，测定了活菌数量随时间的变化。将实验生长曲线与基于液体培养基等温生长的预测结果进行了比较。与等温观察结果一致，受NaCl或pH值影响的凝胶，实验结果与预测结果之间的差异比pH值为7.0且含有0.5%（w/v）NaCl的凝胶更大。
