title: Single bacteria identification by Raman spectroscopy.
abstract: We report on rapid identification of single bacteria using a low-cost, compact, Raman spectroscope. We demonstrate that a 60-s procedure is sufficient to acquire a comprehensive Raman spectrum in the range of 600 to 3300 cm⁻¹. This time includes localization of small bacteria aggregates, alignment on a single individual, and spontaneous Raman scattering signal collection. Fast localization of small bacteria aggregates, typically composed of less than a dozen individuals, is achieved by lensfree imaging over a large field of view of 24 mm². The lensfree image also allows precise alignment of a single bacteria with the probing beam without the need for a standard microscope. Raman scattered light from a 34-mW continuous laser at 532 nm was fed to a customized spectrometer (prototype Tornado Spectral Systems). Owing to the high light throughput of this spectrometer, integration times as low as 10 s were found acceptable. We have recorded a total of 1200 spectra over seven bacterial species. Using this database and an optimized preprocessing, classification rates of ~90% were obtained. The speed and sensitivity of our Raman spectrometer pave the way for high-throughput and nondestructive real-time bacteria identification assays. This compact and low-cost technology can benefit biomedical, clinical diagnostic, and environmental applications.
authors.affiliation: CEA-LETI, Minatec Campus, 17, avenue des Martyrs, 38054 Grenoble Cedex 9, France.
authors.forename: Samy Andrea
authors.initials: SA
authors.lastname: Strola
authors.affiliation: CEA-LETI, Minatec Campus, 17, avenue des Martyrs, 38054 Grenoble Cedex 9, France.
authors.forename: Jean-Charles
authors.initials: JC
authors.lastname: Baritaux
authors.affiliation: CEA-LETI, Minatec Campus, 17, avenue des Martyrs, 38054 Grenoble Cedex 9, France.
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Schultz
authors.affiliation: CEA, LIST, Gif-sur-Yvette, F-91191, France.
authors.forename: Anne Catherine
authors.initials: AC
authors.lastname: Simon
authors.affiliation: CEA-LETI, Minatec Campus, 17, avenue des Martyrs, 38054 Grenoble Cedex 9, France.
authors.forename: Cédric
authors.initials: C
authors.lastname: Allier
authors.affiliation: CEA, LIST, Gif-sur-Yvette, F-91191, France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Espagnon
authors.affiliation: CEA-LETI, Minatec Campus, 17, avenue des Martyrs, 38054 Grenoble Cedex 9, France.
authors.forename: Dorothée
authors.initials: D
authors.lastname: Jary
authors.affiliation: CEA-LETI, Minatec Campus, 17, avenue des Martyrs, 38054 Grenoble Cedex 9, France.
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Dinten
mesh_terms: D001419:Bacteria / Q000737:chemistry* / Q000145:classification* / Q000302:isolation & purification; D015373:Bacterial Typing Techniques / Q000379:methods*; D013059:Spectrum Analysis, Raman / Q000379:methods*