Stable Isotope Raman Microspectroscopy (SIRM) for Quantitative and Nondestructive 2D & 3D Analysis of Biofilms: Microbial Degradation of Microplastic
Final Report Abstract
Stable isotope-based analytical methods are becoming increasingly important in different scientific fields. In this project, the potential of stable isotope Raman microspectroscopy (SIRM) for analysis of microbial degradation of an emerging anthropogenic contaminant – microplastic (MP) was studied. SIRM provides characteristic fingerprint spectra of samples with the spatial resolution of an optical microscope, containing information on stable isotopelabeled substances and the amount of a label (based on the red-shift of bands). It requires no or minimal sample preparation and can be performed without interference of water. The main goal of the project was to develop and evaluate methods based on SIRM for quantitative, non-destructive, and spatially resolved analysis of microorganisms involved in the biodegradation of MP. First, we conducted systematic studies, to investigate the dynamics of stable isotope labeling in single microbial cells with SIRM as a basis for subsequent plastic biodegradation experiments. This was followed by evaluating the potential of different approaches, including direct and reverse stable isotope labeling in combination with different labeled substrates as references and control experiments with non-plastic-biodegrading bacteria. Although reverse labeling SIRM allowed for cost-efficient studies on the carbon assimilation, the need to exclude all carbon sources besides (micro)plastic and, hence, the missing transferability to environmental samples make this approach rather inappropriate for the bio-degradation analysis. The use of deuterated, instead of C-labeled polymers, turned out to be a very suitable alternative (i.e., price, availability, pronounced Raman shift into Ramansilent region). Resonance and conventional Raman spectroscopy showed potential for reliable and complementary applications. While resonance Raman ensured high sensitivity, conventional Raman spectroscopy unravelled metabolic differences of bacteria incubated with MP, compared to other carbon sources, and is therefore suitable to expand the mechanistic understanding of (micro)plastic biodegradation. In summary, we demonstrated that the application of SIRM for the analysis of the biodegradation of D-labeled (micro)plastics can provide unambiguous direct information on the deuterium assimilation by microorganisms at the single-cell level.
Link to the final report
https://doi.org/10.14459/2025md1782854
Publications
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Simple Generation of Suspensible Secondary Microplastic Reference Particles via Ultrasound Treatment. Frontiers in Chemistry, 8.
von der Esch, Elisabeth; Lanzinger, Maria; Kohles, Alexander J.; Schwaferts, Christian; Weisser, Jana; Hofmann, Thomas; Glas, Karl; Elsner, Martin & Ivleva, Natalia P.
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Chemical Analysis of Microplastics and Nanoplastics: Challenges, Advanced Methods, and Perspectives. Chemical Reviews, 121(19), 11886-11936.
Ivleva, Natalia P.
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Multi-element stable isotope Raman microspectroscopy of bacterial carotenoids unravels rare signal shift patterns and single-cell phenotypic heterogeneity. The Analyst, 148(1), 128-136.
Weng, Julian; Müller, Kara; Morgaienko, Oleksii; Elsner, Martin & Ivleva, Natalia P.
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Raman Microspectroscopy to Trace the Incorporation of Deuterium from Labeled (Micro)Plastics into Microbial Cells. Analytical Chemistry, 97(8), 4440-4451.
Müller, Kara; Elsner, Martin; Leung, Anna E.; Wacklin-Knecht, Hanna; Allgaier, Jürgen; Heiling, Maria & Ivleva, Natalia P.
