Farkas J, Andrássy E, Mészáros L, Bánáti D
Department of Refrigeration and Livestock-Products Technology, University of Horticulture and Food Industry, Budapest, Hungary.
Acta Microbiol Immunol Hung. 1995;42(1):19-28.
The growth of untreated Listeria monocytogenes 4ab No. 10 and that of the surviving fraction of its population treated with 0.8 kGy gamma rays was investigated in a microtitreplate system at incubation temperatures between 3 degrees C and 35 degrees C in Tryptic Phosphate Broth (TPB) or Brain Heart Infusion Broth (BHIB) media containing NaCl between 0.25 to 16.75% (w/v), and acidified with citrate-phosphate buffers to pH values between 4.63 and 7.06. The initial viable count was 3 x 10(3)/ml. Time periods to visible growth were recorded. Radiation survivors showed increased salt- and pH-sensitivities and increased minimum temperature for growth in TPB-based media. Adverse effects of sub-optimal environmental factors (reduced water activity, pH and temperature) and radiation injury were much less pronounced in BHIB-based media. Polynomial equations describing the combined effects of hydrogen ion and salt concentrations on the detectable growth at 30 degrees C were constructed for quantitative assessment of interactions. The results demonstrate that combining environmental stresses with low-dose irradiation can control growth of L. monocytogenes.
在微量滴定板系统中，于3℃至35℃的培养温度下，在含有0.25%至16.75%（w/v）NaCl并用柠檬酸盐 - 磷酸盐缓冲液酸化至pH值为4.63至7.06的胰蛋白胨磷酸盐肉汤（TPB）或脑心浸液肉汤（BHIB）培养基中，研究了未处理的单核细胞增生李斯特菌4ab 10号菌株的生长情况以及经0.8 kGyγ射线处理后其存活部分的生长情况。初始活菌数为3×10³/ml。记录可见生长的时间段。辐射存活菌在基于TPB的培养基中显示出对盐和pH的敏感性增加以及生长的最低温度升高。在基于BHIB的培养基中，次优环境因素（降低的水分活度、pH和温度）和辐射损伤的不利影响要小得多。构建了描述氢离子和盐浓度对30℃下可检测生长的联合作用的多项式方程，用于定量评估相互作用。结果表明，将环境胁迫与低剂量辐照相结合可以控制单核细胞增生李斯特菌的生长。
