Differentiating the growth phases of single bacteria using Raman spectroscopy

S.A. Strola (1) , P.R. Marcoux (1) , E. Schultz (1) , R. Perenon (1) , Anne-Catherine Simon (2, 3) , Isabelle Espagnon (2, 3) , C.P. Allier (1) , J.-M. Dinten (1)

1 CEA-LETI - Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information
2 LOAD (CEA, LIST) - Laboratoire Outils d'Analyse des Données (CEA, LIST)
3 LIST (CEA) - Laboratoire d'Intégration des Systèmes et des Technologies

In this paper we present a longitudinal study of bacteria metabolism performed with a novel Raman spectrometer system. Longitudinal study is possible with our Raman setup since the overall procedure to localize a single bacterium and collect a Raman spectrum lasts only 1 minute. Localization and detection of single bacteria are performed by means of lensfree imaging, whereas Raman signal (from 600 to 3200 cm$^{-1}$) is collected into a prototype spectrometer that allows high light throughput (HTVS technology, Tornado Spectral System). Accomplishing time-lapse Raman spectrometry during growth of bacteria, we observed variation in the net intensities for some band groups, e.g. amides and proteins. The obtained results on two different bacteria species, i.e. Escherichia coli and Bacillus subtilis clearly indicate that growth affects the Raman chemical signature. We performed a first analysis to check spectral differences and similarities. It allows distinguishing between lag, exponential and stationary growth phases. And the assignment of interest bands to vibration modes of covalent bonds enables the monitoring of metabolic changes in bacteria caused by growth and aging. Following the spectra analysis, a SVM (support vector machine) classification of the different growth phases is presented. In sum this longitudinal study by means of a compact and low-cost Raman setup is a proof of principle for routine analysis of bacteria, in a real-time and non-destructive way. Real-time Raman studies on metabolism and viability of bacteria pave the way for future antibiotic susceptibility testing.

Mots clés: Chemical detection; Escherichia coli; Industrial research; Metabolism; Physiology; Raman spectroscopy; Spectrometers; Support vector machines; Vibrational spectroscopy; Antibiotic susceptibilities; Chemical signatures; Lensfree imaging; Proof of principles; Raman spectrometers; Raman spectrometries; Spectral differences; SVM(support vector machine); Bacteria; signal processing; statistical analysis; classification; artificial intelligence

Domaines: Bio-Informatique, Biologie Systémique [q-bio.QM]

S.A. Strola, P.R. Marcoux, E. Schultz, R. Perenon, Anne-Catherine Simon, et al.. Differentiating the growth phases of single bacteria using Raman spectroscopy. Proceedings Biomedical Vibrational Spectroscopy VI: Advances in Research and Industry;, Feb 2014, San Francisco, CA, United States. ⟨10.1117/12.2041446⟩. ⟨cea-01839859⟩