Laser light reveals superbugs at molecular-scale resolution

Streptococcus Pneumoniae bacteria are a leading cause of bacterial pneumonia, meningitis, and sepsis and are estimated to have caused around 335,000 worldwide deaths in children aged five years and under in 2015.

Current technologies do not allow a resolution that enables thorough studies of bacterial properties that affect disease development. Electron microscopes show minute detail at the atomic level, but they cannot analyse live specimens because electrons can easily be deflected by molecules in the air, so any bacteria under inspection is held in a vacuum. This makes super-resolution microscopes preferable for biological analysis.

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Dubbed NanoVIB (NANO-scale Visualisation to understand Bacterial virulence and invasiveness - based on fluorescence NANOscopy and VIBrational microscopy), the project will inform the development of new antimicrobials.

To this end, the European Commission has granted the health consortium €5,635,529 through the Photonics Public Private Partnership to build this super-resolution microscope.

In a statement, Professor Jerker Widengren, a project coordinator based at KTH in Sweden, said: "We expect our new microscope prototype to be a next-generation super-resolution system, making it possible to image cellular proteins marked with fluorescence emitters [fluorophores] with a ten-fold higher resolution than with any other fluorescence microscopy technique.”

The project will develop advanced laser, detector and microscopy technologies to enable super-resolution localisation patterns of specific proteins. These will be overlaid with light-scattering images, correlating these patterns with local structures and chemical conditions in the bacteria.

Prof Widengren said: “Using laser light, this new microscope will show how bacterial proteins localise on the surface of bacteria, allowing scientists to study the interaction of the pathogen with immune and host cells.

“It works based on the so-called MINFLUX concept, where infrared laser light excites fluorophore-labelled molecules in a triangulated manner – leading to an increased resolution. The user can then fine-tune the microscopic imaging to previously unimaginable resolutions.

“MINFLUX microscopy will make it possible to resolve how certain pneumococcal surface proteins are distributed on the bacteria under different cell division stages, and whether these proteins are localised in such a way that specific, extra sensitive surface regions of the bacteria, a critical step of the cell division, are protected from immune activation.”

The NanoVIB team reportedly took their inspiration from a previous EU-funded project, Fluodiamon, which analysed how specific proteins are spatially distributed in breast and prostate cancer cells compared to those in corresponding non-cancer cells, demonstrating a new basis for cancer diagnosis.

The project concludes in 2024.