Simultaneous Raman and Infrared Spectroscopy of Stable Isotope Labelled Escherichia coli



Lima, Cassio, Muhamadali, Howbeer and Goodacre, Royston ORCID: 0000-0003-2230-645X
(2022) Simultaneous Raman and Infrared Spectroscopy of Stable Isotope Labelled Escherichia coli. SENSORS, 22 (10). 3928-.

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Abstract

We report the use of a novel technology based on optical photothermal infrared (O-PTIR) spectroscopy for obtaining simultaneous infrared and Raman spectra from the same location of the sample allowing us to study bacterial metabolism by monitoring the incorporation of <sup>13</sup>C- and <sup>15</sup>N-labeled compounds. Infrared data obtained from bulk populations and single cells via O-PTIR spectroscopy were compared to conventional Fourier transform infrared (FTIR) spectroscopy in order to evaluate the reproducibility of the results achieved by all three approaches. Raman spectra acquired were concomitant with infrared data from bulk populations as well as infrared spectra collected from single cells, and were subjected to principal component analysis in order to evaluate any specific separation resulting from the isotopic incorporation. Similar clustering patterns were observed in infrared data acquired from single cells via O-PTIR spectroscopy as well as from bulk populations via FTIR and O-PTIR spectroscopies, indicating full incorporation of heavy isotopes by the bacteria. Satisfactory discrimination between unlabeled (<i>viz</i>. <sup>12</sup>C<sup>14</sup>N), <sup>13</sup>C<sup>14</sup>N- and <sup>13</sup>C<sup>15</sup>N-labeled bacteria was also obtained using Raman spectra from bulk populations. In this report, we also discuss the limitations of O-PTIR technology to acquire Raman data from single bacterial cells (with typical dimensions of 1 × 2 µm) as well as spectral artifacts induced by thermal damage when analyzing very small amounts of biomass (a bacterium tipically weighs ~ 1 pg).

Item Type: Article
Uncontrolled Keywords: Raman, O-PTIR, bacteria, stable isotope labeling, spectroscopy
Divisions: Faculty of Health and Life Sciences
Faculty of Health and Life Sciences > Institute of Systems, Molecular and Integrative Biology
Depositing User: Symplectic Admin
Date Deposited: 30 Jun 2022 14:22
Last Modified: 09 Mar 2023 06:16
DOI: 10.3390/s22103928
Open Access URL: https://www.mdpi.com/1424-8220/22/10/3928
Related URLs:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3157438