Department of Food Science and Technology, The Ohio State University, Columbus, OH 43210, USA.
Int J Food Microbiol. 2010 May 30;140(1):49-56. doi: 10.1016/j.ijfoodmicro.2010.02.010. Epub 2010 Feb 19.
The effects of high hydrostatic pressure (HHP) and nisin treatment alone and in combination on cellular components and viability of two Salmonella enterica subsp. enterica serovar Enteritidis (S. Enteritidis) strains were evaluated by differential scanning calorimetry (DSC) and plate counting in order to evaluate the relative resistance and optimize the treatment conditions. S. Enteritidis FDA and OSU 799 strains were subjected to HHP (0.1-550 MPa for 10 min at 25 degrees C) alone and in combination with nisin (200 IU/ml nisin) in culture broth. HHP (up to 200 MPa) or the nisin alone did not affect the viability and cellular components of either strain. An 8-log cfu/ml reduction was observed after a pressure treatment at 500 MPa for the FDA strain and 450 MPa for the OSU 799 strain. When nisin was added, a similar reduction was obtained at 400 MPa for FDA strain and 350 MPa for the OSU 799 strain. The decrease in apparent enthalpy appeared to be mainly due to reduction in the ribosome denaturation peak for both the pressure alone and the pressure-nisin combination treatments. HHP facilitated penetration of nisin into the cell above 100 MPa pressure. Monitoring through DNA-binding probes the effect of pressure and nisin treatments on DNA in vivo showed that nisin did not affect DNA at 200 IU/ml. The apparent enthalpy data obtained from DSC can be used for optimization of pressure levels to reduce a microbial population in the presence of nisin.
采用差示扫描量热法（DSC）和平板计数法评估了单纯高静压（HHP）和乳链菌肽（nisin）处理以及二者联合处理对 2 株肠炎沙门氏菌亚种肠炎沙门氏菌（S. Enteritidis）细胞成分和活力的影响，旨在评估相对抗性并优化处理条件。将 S. Enteritidis FDA 和 OSU 799 菌株在培养基中分别单独或与乳链菌肽（200 IU/ml 乳链菌肽）联合进行 HHP（25°C 下 10 分钟 0.1-550 MPa）处理。HHP（高达 200 MPa）或单独的乳链菌肽对两种菌株的活力和细胞成分均无影响。FDA 菌株经 500 MPa 处理、OSU 799 菌株经 450 MPa 处理后，活菌数减少 8 个对数单位/ml。当添加乳链菌肽时，FDA 菌株在 400 MPa、OSU 799 菌株在 350 MPa 下可获得类似的减少量。单独的压力处理和压力-乳链菌肽联合处理后，表观焓的降低似乎主要是由于核糖体变性峰的减少。HHP 有助于乳链菌肽在超过 100 MPa 压力下进入细胞。通过 DNA 结合探针监测压力和乳链菌肽处理对体内 DNA 的影响表明，乳链菌肽在 200 IU/ml 时不会影响 DNA。从 DSC 获得的表观焓数据可用于优化压力水平，以在存在乳链菌肽的情况下减少微生物群体。
