Comparison of Escherichia coli surface attachment methods for single-cell microscopy

Yao-Kuan Wang,Fan Bai,Teuta Pilizota,Ssu-Yuan Lin,Chien-Jung Lo,Ekaterina Krasnopeeva

doi:10.1038/s41598-019-55798-0

Yao-Kuan Wang, Fan Bai + Show 4 more

Open Access

https://doi.org/10.1038/s41598-019-55798-0

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Abstract

For in vivo, single-cell imaging bacterial cells are commonly immobilised via physical confinement or surface attachment. Different surface attachment methods have been used both for atomic force and optical microscopy (including super resolution), and some have been reported to affect bacterial physiology. However, a systematic comparison of the effects these attachment methods have on the bacterial physiology is lacking. Here we present such a comparison for bacterium Escherichia coli, and assess the growth rate, size and intracellular pH of cells growing attached to different, commonly used, surfaces. We demonstrate that E. coli grow at the same rate, length and internal pH on all the tested surfaces when in the same growth medium. The result suggests that tested attachment methods can be used interchangeably when studying E. coli physiology.

Highlights

For in vivo, single-cell imaging bacterial cells are commonly immobilised via physical confinement or surface attachment
To estimate the effect of different immobilisation assays on bacterial physiology we examine the growth rate, size and division accuracy of individual cells growing on each specific surface
Good surface attachment is an important requirement for bacterial single-cell studies using optical microscopy

Summary

Introduction

Single-cell imaging bacterial cells are commonly immobilised via physical confinement or surface attachment. A systematic comparison of the effects these attachment methods have on the bacterial physiology is lacking We present such a comparison for bacterium Escherichia coli, and assess the growth rate, size and intracellular pH of cells growing attached to different, commonly used, surfaces. Immobilisation methods vary depending on the application, but typically fall into one of the two categories: use of physical confinement or attachment to the surface via specific molecules. The former group includes microfluidic platforms capable of mechanical trapping[6,7], where some popular examples include the “mother machine”[8], CellASIC9 or MACS10 devices, and porous membranes such as agarose gel pads[2,11,12,13]. We measure several physiological traits during growth on the specific surface, including growth rate, size and intracellular pH, and find that tested immobilisation methods do not differ; growth rate and cell size are surface-attachment independent

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