García-Lara J, Martínez J, Vilamú M, Vives-Rego J
Departament de Microbiologia, Universitat de Barcelona, Spain.
J Gen Microbiol. 1993 Jul;139(7):1425-31. doi: 10.1099/00221287-139-7-1425.
The starvation-survival of Escherichia coli in seawater was assessed by plate and epifluorescence counts, 3H-label decrease, cellular DNA concentrations, and metabolic activities. These assays were performed on two types of populations, adapted and non-adapted to seawater. The number of viable cells in the adapted population remained constant throughout starvation-survival in sterile seawater. In contrast, a significant decrease in the ability of the non-adapted E. coli to form colonies on plates following starvation-survival in sterile seawater was observed. However, this drop in viable counts was not mirrored by the epifluorescence counts and 3H-label, which did not show major changes for either population during the experiments, indicating maintenance of the number of cells. In addition, a significant increase in and subsequent maintenance of DNA content and thymidine incorporation was observed for both populations during starvation-survival in sterile seawater. The changes in cell-attached exoproteolytic activity and electron transport system activity showed that adapted and non-adapted E. coli cells maintain their metabolic potential. Cell-free exoproteolytic activity was drastically reduced in both populations. Adapted cells showed higher electron transport system activity and thymidine incorporation than non-adapted cells at the onset of starvation-survival. The effect of previous adaptation on E. coli starvation-survival, as assessed by plate counts and 3H-label decrease, was also observed in raw seawater. It seems from these data that the biological potential of E. coli cells suspended in sterile seawater has not been switched off or impaired seriously.
通过平板计数、落射荧光计数、³H标记减少量、细胞DNA浓度和代谢活性来评估大肠杆菌在海水中的饥饿存活情况。这些测定针对两种类型的菌群进行，即适应海水的菌群和未适应海水的菌群。在无菌海水中进行饥饿存活实验期间，适应菌群中的活细胞数量保持恒定。相比之下，在无菌海水中进行饥饿存活实验后，未适应的大肠杆菌在平板上形成菌落的能力显著下降。然而，这种活细胞计数的下降并未在落射荧光计数和³H标记中得到体现，在实验过程中这两个菌群的这些指标均未显示出重大变化，表明细胞数量保持稳定。此外，在无菌海水中进行饥饿存活实验期间，两个菌群的DNA含量和胸苷掺入量均显著增加并随后保持稳定。细胞附着的外蛋白水解活性和电子传递系统活性的变化表明，适应和未适应的大肠杆菌细胞都保持了它们的代谢潜能。两个菌群的无细胞外蛋白水解活性都大幅降低。在饥饿存活开始时，适应细胞比未适应细胞表现出更高的电子传递系统活性和胸苷掺入量。通过平板计数和³H标记减少量评估，先前适应对大肠杆菌饥饿存活的影响在天然海水中也有观察到。从这些数据来看，悬浮在无菌海水中的大肠杆菌细胞的生物学潜能似乎并未被严重关闭或损害。
