A novel method for single bacteria identification by Raman spectroscopy

Abstract

In this paper we present results on single bacteria rapid identification obtained with a low-cost and compact Raman spectrometer. At present, we demonstrate that a 1 minute procedure, including the localization of single bacterium, is sufficient to acquire comprehensive Raman spectrum in the range of 600 to 3300 cm -1 . Localization and detection of single bacteria is performed by means of lensfree imaging over a large field of view of 24 mm 2 . An excitation source of 532 nm and 30 mW illuminates single bacteria to collect Raman signal into a Tornado Spectral Systems prototype spectrometer (HTVS technology). The acquisition time to record a single bacterium spectrum is as low as 10 s owing to the high light throughput of this spectrometer. The spectra processing features different steps for cosmic spikes removal, background subtraction, and gain normalization to correct the residual inducted fluorescence and substrate fluctuations. This allows obtaining a fine chemical fingerprint analysis. We have recorded a total of 1200 spectra over 7 bacterial species (E. coli, Bacillus species, S. epidermis, M. luteus, S. marcescens). The analysis of this database results in a high classification score of almost 90 %. Hence we can conclude that our setup enables automatic recognition of bacteria species among 7 different species. The speed and the sensitivity (<30 minutes for localization and spectra collection of 30 single bacteria) of our Raman spectrometer pave the way for high-throughput and non-destructive real-time bacteria identification assays. This compact and low-cost technology can benefit biomedical, clinical diagnostic and environmental applications.

Recent progress on the development of antibiotics from the genus Micromonospora

“…Thus, it is now possible to do mass spectrometric analysis of several hundred metabolites, with dense coverage of primary metabolism, in complex biological extracts and at throughputs of >1000 samples per day and the process can also be directed to specific target like enzyme activity [278,279]. The recent Advances in Infrared and Raman spectroscopy are also helpful in the rapid and low cost differentiation, identification and metabolome characterization of microbial strains [280,281]. Zhao et al [282] studied FT-IR spectra of Micromonospora strains isolated from coastal sediments and found that this method can be applied to indicate in which environmental isolates have been cultured previously.…”

Perspective on Improving Environmental Monitoring of Biothreats

“…Raman spectroscopy has been evaluated as a potential technology platform for a reagent-less environmental monitoring system (Ronningen and Bartko, 2009 ; National Academy of Sciences, 2013 ; Kusić et al, 2014 ; Schultz et al, 2014 ; Zhou et al, 2014 ; Baritaux et al, 2015 ; Hlaing et al, 2016 ; Stöckel et al, 2016 ; Gao et al, 2017 ; Lorenz et al, 2017 ). This approach relies on the notion that target biological agents exhibit reproducible Raman profiles that are sufficiently distinct from the profiles of material routinely observed in aerosols, enabling triage of aerosol samples (i.e., discrimination of “suspect” aerosol samples from a large volume of non-relevant samples).…”