Bacteria are just not a “bag of enzymes”! ​ 

For decades, scientists thought bacteria is a simple organism which lack of internal order and complexity of eukaryotic cells. Today, thanks to advanced techniques we know that bacteria are versatile microorganisms with a large range of cellular components and functions beyond just enzymes. They contains certain essential components such as cell membrane, nucleoid and ribosomes to survive and thrive. Various processes are carried out in the cell to maintain internal and external cellular organization such as cell shape and elongation, chromosome organization, segregation, cell division and growth. 

The rod-shaped bacterium Escherichia coli,is one of the most extensively studied and well-understood specie among the bacteria.

Its significance in genetics, biotechnology, and microbiology makes it a cornerstone of biological research and a valuable model organism for understanding fundamental biological processes. E. coli has a single circular chromosome which is super compacted that consist of approximately 4.6 million base pairs of DNA. Chromosome organization and segregation is one of the crucial event in the cell. On the other hand, E. coli consist of Gram-negative membrane which contains outer membrane, periplasmic space and inner membrane. Especially outer membrane plays critical role such as protection against antibiotic, pathogenicity, selective permeability, transportation system and motility.

E coli cell stained with WGA-AF647 acquired in 3D-dSTORM

To understand these sophisticated structures in bacteria, we visualized nanoscale resolution of E. coli chromosome and membrane simultaneously by using PAINT technique in Ultimate 3D configuration of Abbelight SAFe MN360 plateform.

Bacterial chromosome and membrane is labelled with spontaneously blinking dyes JF646-Hoescht and Potomac Gold, respectively. 50 μm² homogenous illumination is set for imaging, 560 and 640 lasers are used simultaneously to excite Potomac Gold and JF646. Thanks to dual camera modulewith automated band filters, both structures were imaged in same time for 15 000 frames with Abbelight Neo Live Imaging software. DBSCAN algorithm is used to cluster both membrane and chromosome with number of localization which were processed and detected with Abbelight Neo Analysis software.​ 

This fast-growing E. coli cells contain 2 pairs of replicated chromosome in a single cell. This technique can be also used observe subcellular localization of other proteins in reference to bacterial membrane. It can be also combined with other imaging methods such as PALM and STORM. 


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[2] Surovtsev, I. V. & Jacobs-Wagner, C. Subcellular Organization: A Critical Feature of Bacterial Cell Replication. Cell 172, 1271–1293 (2018).

[3] Zachary D Blount (2015) The Natural History of Model Organisms: The unexhausted potential of E. coli eLife 4:e05826.

[4] Spahn, C.K., Glaesmann, M., Grimm, J.B. et al. A toolbox for multiplexed super-resolution imaging of the E. coli nucleoid and membrane using novel PAINT labels. Sci Rep 8, 14768 (2018).