The last generation of bacterial growth in limiting nutrient.
The last generation of bacterial growth in limiting nutrient.
复制标题
DOI：
10.1186/1752-0509-7-27
复制
发表时间：
2013-03-25
影响因子：
--
通讯作者：
Alon U
中科院分区：
文献类型：
--
作者：
Bren A;Hart Y;Dekel E;Koster D;Alon U
细菌生长作为营养物质的函数已经研究了几十年，但仍然不完全清楚。特别是，由于条件的快速变化，动态变化环境下的生长规律一直很难探索。在这里，我们通过机器人检测来解决这一挑战，并在批培养的整个生长曲线上以高时间分辨率测量细菌生长速度、启动子活性和底物水平。作为一个模型系统，我们研究了大肠杆菌在氮或碳限制下的生长，并探索了在营养水平可能迅速下降的最后一代生长中的动态。我们发现，在限制氮或碳的情况下，生长会突然停止，但当营养不受限制时，生长会逐渐放缓。通过测量3分钟时间分辨率下的生长速率，并推断瞬时底物水平S，我们发现营养限制下生长速率μ的下降遵循莫诺定律。通过跟踪不同基因的启动子活性，我们发现氮素或碳素限制下的生长突然停止伴随着相关营养同化途径中基因表达的脉冲式上调。我们进一步发现，生长的急剧停止是以同化途径中存在调节蛋白为条件的。观察到的生长急剧停止伴随着同化基因的脉冲表达，使细菌能够补偿营养物质的下降，这表明细胞使用了一种策略，在限制底物的情况下延长指数生长。
Bacterial growth as a function of nutrients has been studied for decades, but is still not fully understood. In particular, the growth laws under dynamically changing environments have been difficult to explore, because of the rapidly changing conditions. Here, we address this challenge by means of a robotic assay and measure bacterial growth rate, promoter activity and substrate level at high temporal resolution across the entire growth curve in batch culture. As a model system, we study E. coli growing under nitrogen or carbon limitation, and explore the dynamics in the last generation of growth where nutrient levels can drop rapidly. We find that growth stops abruptly under limiting nitrogen or carbon, but slows gradually when nutrients are not limiting. By measuring growth rate at a 3 min time resolution, and inferring the instantaneous substrate level, s, we find that the reduction in growth rate μ under nutrient limitation follows Monod’s law, . By following promoter activity of different genes we found that the abrupt stop of growth under nitrogen or carbon limitation is accompanied by a pulse-like up-regulation of the expression of genes in the relevant nutrient assimilation pathways. We further find that sharp stop of growth is conditional on the presence of regulatory proteins in the assimilation pathway. The observed sharp stop of growth accompanied by a pulsed expression of assimilation genes allows bacteria to compensate for the drop in nutrients, suggesting a strategy used by the cells to prolong exponential growth under limiting substrate.
登录
查看更多内容
影响因子：
3.2
作者：
Atkinson, MR;Blauwkamp, TA;Ninfa, AJ
通讯作者：
Ninfa, AJ
影响因子：
3.5
作者：
Cormack, BP;Valdivia, RH;Falkow, S
通讯作者：
Falkow, S
影响因子：
64.8
作者：
Dekel, E;Alon, U
通讯作者：
Alon, U
DOI：
10.1007/bf00871219
发表时间：
1993-01-01
影响因子：
2.6
作者：
JANNASCH, HW;EGLI, T
通讯作者：
EGLI, T
大肠杆菌K-12的构造框架，单基因敲除突变体：Keio Collection。
影响因子：
9.9
作者：
通讯作者：
--