Image-based physical characterization of magnetotactic bacteria from an environmental sample

Mara Smite; Mihails Birjukovs; Mila Sirinelli-Kojadinovic; Sandrine Grosse; Agnese Kokina; Janis Liepins; Dita Gudra; Megija Lunge; Davids Fridmanis; Mihaly Posfai; Andrejs Cebers; Damien Faivre; Guntars Kitenbergs

arXiv · 2506.04011

Image-based physical characterization of magnetotactic bacteria from an environmental sample

Mara Smite·Mihails Birjukovs·Mila Sirinelli-Kojadinovic·Sandrine Grosse·Agnese Kokina·Janis Liepins·Dita Gudra·Megija Lunge·Davids Fridmanis·Mihaly Posfai·Andrejs Cebers·Damien Faivre·Guntars Kitenbergs

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Abstract

Magnetotactic bacteria (MTB) are a diverse group of microorganisms that are able to biomineralize magnetic nanoparticles. Most MTB remain uncultured, making population-level characterization from natural environments difficult. We report the discovery of a new and diverse MTB-rich site in the Ogre River, Latvia, and present an integrated approach combining 16S rRNA sequencing, transmission electron microscopy, and novel open-source, automated image-based physical methods to characterize bacteria populations within environmental samples. We introduce a pipeline for cell velocimetry using a static magnetic field and a method to classify cell populations based on their magnetic moment using a modified U-turn method where cell behavior is studied in an alternating magnetic field. This study demonstrates that our physical analysis methods provide a powerful, fast, and robust toolset for MTB population analysis in complex environmental samples.

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Mara Smite, Mihails Birjukovs, Mila Sirinelli-Kojadinovic, Sandrine Grosse, Agnese Kokina, Janis Liepins, Dita Gudra, Megija Lunge, Davids Fridmanis, Mihaly Posfai, Andrejs Cebers, Damien Faivre, Guntars Kitenbergs. 2025-06-04. Image-based physical characterization of magnetotactic bacteria from an environmental sample. https://arxiv.org/abs/2506.04011

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