Detection of molecular changes induced by antibiotics in Escherichia coli using vibrational spectroscopy

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Molecular and biomolecular spectroscopy, 2017-08, Vol.183, p.395-401
• Main Authors: Xuan Nguyen, N.T., Sarter, Samira, Hai Nguyen, N., Daniel, Philippe
• Format: Article
• Language: English
• Subjects: Antibiotics; Escherichia coli; Infra-red spectroscopy; Physics; Raman spectroscopy
• ISSN: 1386-1425; 1873-3557
• DOI: 10.1016/j.saa.2017.04.077

This study aimed to test Raman (400–1800cm−1) and Infra-red (1900–500cm−1) spectroscopies followed by statistical analysis (principal component analysis) to detect molecular changes induced by antibiotics (ampicillin, cefotaxime – cell wall synthesis inhibitors, tetracycline – protein synthesis inhibitor, ciprofloxacin – DNA synthesis inhibitor) against Escherichia coli TOP10. In case of ampicillin and cefotaxime, a decrease in protein bands in both Raman (1240, 1660cm−1), and IR spectra (1230, 1530, 1630cm−1), and an increase in carbohydrate bands (1150, 1020cm−1) in IR spectra were observed. Tetracycline addition caused an increase in nucleic acid bands (775, 1478, 1578cm−1), a sharp decrease in phenylalanine (995cm−1) in Raman spectra and the amide I and amide II bands (1630, 1530cm−1) in IR spectra, an increase in DNA in both Raman (1083cm−1) and IR spectra (1080cm−1). Regarding ciprofloxacin, an increase in nucleic acids (775, 1478, 1578cm−1) in Raman spectra and in protein bands (1230, 1520, 1630cm−1), in DNA (1080cm−1) in IR spectra were detected. Clear discrimination of antibiotic-treated samples compared to the control was recorded, showing that Raman and IR spectroscopies, coupled to principal component analysis for data, could be used to detect molecular modifications in bacteria exposed to different classes of antibiotics. These findings contribute to the understanding of the mechanisms of action of antibiotics in bacteria. Raman and IR spectra of E. coli TOP10 without (Con) and with Amp, Ctx, Tet recorded 120min and Cip recorded 90min after the antibiotic addition. [Display omitted] •Raman, IR were used to detect metabolic changes during growth phases of E. coli.•Metabolic changes in nucleic acids, lipids and proteins were observed.•Molecular changes induced by Amp, Ctx, Tet and Cip were detected.•Spectral discrimination by nucleic acids, proteins, phenylalanine in Raman spectra•Spectral differentiation by carbohydrate, and protein bands in IR spectra