Bacterial ageing in the absence of external stressors

Abstract

Evidence of ageing in the bacterium Escherichia coli was a landmark finding in senescence research, as it suggested that even organisms with morphologically symmetrical fission may have evolved strategies to permit damage accumulation. However, recent work has suggested that ageing is only detectable in this organism in the presence of extrinsic stressors, such as the fluorescent proteins and strong light sources typically used to excite them. Here we combine microfluidics with brightfield microscopy to provide evidence of ageing in E. coli in the absence of these stressors. We report (i) that the doubling time of the lineage of cells that consistently inherits the ‘maternal old pole’ progressively increases with successive rounds of cell division until it reaches an apparent asymptote, and (ii) that the parental cell divides asymmetrically, with the old pole daughter showing a longer doubling time and slower glucose accumulation than the new pole daughter. Notably, these patterns arise without the progressive accumulation or asymmetric partitioning of observable misfolded-protein aggregates, phenomena previously hypothesized to cause the ageing phenotype. Our findings suggest that ageing is part of the naturally occurring ecologically-relevant phenotype of this bacterium and highlight the importance of alternative mechanisms of damage accumulation in this context. This article is part of a discussion meeting issue ‘Single cell ecology’.

Fluorescent macrolide probes – synthesis and use in evaluation of bacterial resistance

“…Therefore, we complemented the measurements above with studies carried out using our previously established single-cell microfluidics-microscopy assay. [34][35][36][37] This technique enables single-cell studies to address the impact of phenotypic heterogeneity 38,39 on intracellular drug accumulation and efficacy. 40,41 As a proof of concept, we examined the real-time uptake of roxi-C 4 -Tz-NBD 9 into E. coli (BW25113, a K12 strain) and susceptible S. aureus (MSSA476).…”

Single cell ecology

“…This category includes work that makes use of technical progress in the manipulation of cells allowing them to be recovered, studied or exposed to chemical, physical or biological stimuli in a controlled and measurable manner. Work reported here includes articles that showcase approaches focusing on microfluidic systems that can be used to manipulate cells [45], or the growth of a population of cells [46,47] so they can be studied in detail. Microfluidic devices are essentially tiny plumbing systems, with dimensions ranging from one millimetre down to one micrometre, that is a hundred times smaller than the diameter of a human hair.…”

Determination of the Membrane Transport Properties of Jurkat Cells with a Microfluidic Device

“…Researchers found evidence that mass transfer properties of a biological membrane could be influenced and/or regulated by many factors, such as: cell age [11], attractive optical potential [12], specificity of membrane proteins [13] and shape of aquaporins on the cell membrane [14]. Several devices have been developed to quantify Lp and Ps for different cells and were thoroughly reviewed by McGrath [15] and Zhao [16].…”