Resuscitation rate in different enterococcal species in the viable but non-culturable state
Resuscitation rate in different enterococcal species in the viable but non-culturable state
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DOI：
10.1046/j.1365-2672.2001.01476.x
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发表时间：
2001-12-01
影响因子：
4
通讯作者：
Canepari, P
中科院分区：
文献类型：
--
作者：
Lleò, MM;Bonato, B;Canepari, P
活的但不可培养（VBNC）状态是细菌在暴露于环境压力时采取的生存策略。当处于这种状态时，细菌不再可在常规生长培养基上培养，但细胞显示代谢活性并保持致病因子/基因，并且在某些情况下，已显示从VBNC状态复苏。人类病原体和粪便污染指标都描述了这种状态。在这项研究中，我们提出的证据进入VBNC状态的不同肠球菌物种在寡营养microcosm.Methods和结果：VBNC状态的细胞的生存能力的持续时间进行测量，无论是通过检测pbp5 mRNA的存在，或通过量化他们的复苏能力。肠球菌表现出不同的行为。粪肠球菌和肠球菌在2周内进入VBNC状态，并保持该状态3个月。在所描述的实验中，一旦细胞进入VBNC状态，复苏率为1：10000细胞，并在随后的3个月内逐渐下降至不可检测的水平。然而，屎肠球菌可培养4周。在这段时间之后，当群体完全不可培养时，细胞的可复苏性远低于其他肠球菌，并且仅在较窄的时间间隔（2周）内。结论：这些结果表明，粪肠球菌和肠球菌进入VBNC状态，但屎肠球菌在贫营养实验室环境中倾向于死亡，而不是进入VBNC状态。这些实验可能会模拟人类和动物在自然环境中释放肠球菌时发生的情况。
Aims: The viable but non-culturable (VBNC) state is a survival strategy adopted by bacteria when exposed to environmental stress. When in this state bacteria are no longer culturable on conventional growth media, but cells display metabolic activity and maintain pathogenicity factors/genes and, in some cases, resuscitation from the VBNC state has been shown. This state has been described for both human pathogens and faecal pollution indicators. In this study, we present evidence for entry of different enterococcal species into the VBNC state in an oligotrophic microcosm.Methods and Results: The duration of the viability of the cells in the VBNC state was measured either by detecting the presence of pbp5 mRNA or by quantifying their resuscitation capability. Enterococci showed different behaviours. Enterococcus faecalis and Enterococcus hirae entered into the VBNC state within 2 weeks and remained in that state for 3 months. In the experiments described the resuscitation rate was 1 : 10 000 cells as soon as the cells entered the VBNC state and decreased gradually to undetectable levels over the following 3 months. Enterococcus faecium, however, remained culturable Up to 4 weeks. After this time period, when the population was totally unculturable, the cells were far less resuscitable than other enterococci and only over a narrow time interval (2 weeks).Conclusions: These results suggest that Ent. faecalis and Ent. hirae enter the VBNC state but that Ent. faecium, in an oligotrophic laboratory environment, tends to die instead of entering the VBNC state.Significance and Impact of the Study: These experiments may mimic what happens when enterococci are released by humans and animals in natural environments.