The biochemical origins of the surface-enhanced Raman spectra of bacteria: a metabolomics profiling by SERS.
The dominant molecular species contributing to the surface-enhanced Raman spectroscopy (SERS) spectra of bacteria excited at 785 nm are the metabolites of purine degradation: adenine, hypoxanthine, xanthine, guanine, uric acid, and adenosine monophosphate. These molecules result from the starvation response of the bacterial cells in pure water washes following enrichment from nutrient-rich environments. Vibrational shifts due to isotopic labeling, bacterial SERS spectral fitting, SERS and mass spectrometry analysis of bacterial supernatant, SERS spectra of defined bacterial mutants, and the enzymatic substrate dependence of SERS spectra are used to identify these molecular components. The absence or presence of different degradation/salvage enzymes in the known purine metabolism pathways of these organisms plays a central role in determining the bacterial specificity of these purine-base SERS signatures. These results provide the biochemical basis for the development of SERS as a rapid bacterial diagnostic and illustrate how SERS can be applied more generally for metabolic profiling as a probe of cellular activity. Graphical Abstract Bacterial typing by metabolites released under stress.
Department of Chemistry, Boston University, 590 Commonwealth Ave., Boston, MA, 02215, USA. ranjith@bu.edu.|The Photonics Center, Boston University, 8 Saint Mary's St., Boston, MA, 02215, USA. ranjith@bu.edu.
W Ranjith
WR
Premasiri
Division of Infectious Diseases, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, 181 Longwood Ave., Boston, MA, 02115, USA.
Jean C
JC
Lee
The Photonics Center, Boston University, 8 Saint Mary's St., Boston, MA, 02215, USA.|Fraunhofer Center for Manufacturing Innovation, 15 Saint Mary's St., Brookline, MA, 02446, USA.|Department of Biomedical Engineering, Boston University, 44 Cummington St., Boston, MA, 02215, USA.
Alexis
A
Sauer-Budge
Center for Biomedical Mass Spectrometry, Boston University School of Medicine, Boston, MA, 02118, USA.
Roger
R
Théberge
Center for Biomedical Mass Spectrometry, Boston University School of Medicine, Boston, MA, 02118, USA.
Catherine E
CE
Costello
Department of Chemistry, Boston University, 590 Commonwealth Ave., Boston, MA, 02215, USA. lziegler@bu.edu.|The Photonics Center, Boston University, 8 Saint Mary's St., Boston, MA, 02215, USA. lziegler@bu.edu.
Lawrence D
LD
Ziegler
D001419:Bacteria / Q000378:metabolism*; D007553:Isotope Labeling; D055432:Metabolomics; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D013059:Spectrum Analysis, Raman / Q000379:methods*; D013499:Surface Properties
Bacteria; Metabolic profiling; Nucleotide degradation; Purine metabolism; Surface-enhanced Raman spectroscopy