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Discrimination of Stressed and Non-Stressed Food-Related Bacteria Using Raman-Microspectroscopy

  • As the identification of microorganisms becomes more significant in industry, so does the utilization of microspectroscopy and the development of effective chemometric models for data analysis and classification. Since only microorganisms cultivated under laboratory conditions can be identified, but they are exposed to a variety of stress factors, such as temperature differences, there is a demand for a method that can take these stress factors and the associated reactions of the bacteria into account. Therefore, bacterial stress reactions to lifetime conditions (regular treatment, 25 °C, HCl, 2-propanol, NaOH) and sampling conditions (cold sampling, desiccation, heat drying) were induced to explore the effects on Raman spectra in order to improve the chemometric models. As a result, in this study nine food-relevant bacteria were exposed to seven stress conditions in addition to routine cultivation as a control. Spectral alterations in lipids, polysaccharides, nucleic acids, and proteins were observed when compared to normal growth circumstances without stresses. Regardless of the involvement of several stress factors and storage times, a model for differentiating the analyzed microorganisms from genus down to strain level was developed. Classification of the independent training dataset at genus and species level for Escherichia coli and at strain level for the other food relevant microorganisms showed a classification rate of 97.6%.

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Document Type:Article
Author:Daniel Klein, René Breuch, Jessica Reinmüller, Carsten Engelhard, Peter Kaul
Parent Title (English):Foods
Article Number:1506
Number of pages:12
Place of publication:Basel
Publishing Institution:Hochschule Bonn-Rhein-Sieg
Date of first publication:2022/05/22
Copyright:© 2022 by the authors. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license.
Funding:This research was funded by the German Research Foundation (DFG) as part of the research training group GRK 1564 ‘Imaging New Modalities’. This work was also supported and financed by the Safety and Security Research Institute as well as the Graduate Institute of the Bonn-Rhein-Sieg University of Applied Sciences.
Keyword:Raman-microspectroscopy; bacteria; classification; discriminant analysis; stress response
Departments, institutes and facilities:Fachbereich Angewandte Naturwissenschaften
Institut für Sicherheitsforschung (ISF)
Dewey Decimal Classification (DDC):6 Technik, Medizin, angewandte Wissenschaften / 66 Chemische Verfahrenstechnik / 664 Lebensmitteltechnologie
Open access funding:Hochschule Bonn-Rhein-Sieg / Graduierteninstitut
Entry in this database:2022/06/10
Licence (German):License LogoCreative Commons - CC BY - Namensnennung 4.0 International