Identification of a resonance Raman marker for cytochrome to monitor stress responses in Escherichia coli

Mukherjee, R and Verma, T and Nandi, D and Umapathy, S (2020) Identification of a resonance Raman marker for cytochrome to monitor stress responses in Escherichia coli. In: Analytical and Bioanalytical Chemistry, 412 (22). pp. 5379-5388.

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Abstract

Raman spectroscopy and resonance Raman spectroscopy are widely used to study bacteria and their responses to different environmental conditions. In the present study, the identification of a novel resonance Raman peak for Escherichia coli, recorded with 633 nm laser excitation is discussed. A peak at 740 cm�1 is observed exclusively with 633 nm excitation but not with 514 nm or 785 nm excitation. This peak is absent in the lag phase but appears in the log phase of bacterial growth. The intensity of the peak increases at high temperature (45 °C) compared with growth at low temperature (25 °C) or the physiological temperature (37 °C). Although osmotic stress lowered bacterial growth, the intensity of this peak was unaffected. However, treatment with chemical uncouplers of oxidative phosphorylation resulted in significantly lower intensity of this Raman band, indicating its possible involvement in respiration. Cytochromes, a component of bacterial respiration� can show resonance enhancement at 633 nm due to the presence of a shoulder in that region depending on the type and conformation of cytochrome. Therefore, the peak intensity was monitored in different genetic mutants of E. coli lacking cytochromes. This peak is absent in the Escherichia coli mutant lacking cydB, but not ccmE, demonstrating the contribution of cytochrome bd subunit II in the peak�s origin. In future, this newly found cytochrome marker can be used for biochemical assessment of bacteria exposed to various conditions. Overall, this finding opens the scope for use of red laser excitation in resonance Raman in monitoring stress and respiration in bacteria.

Item Type:	Journal Article
Publication:	Analytical and Bioanalytical Chemistry
Publisher:	Springer
Additional Information:	Copy right for this article belongs to Springer
Keywords:	Escherichia coli; Raman spectroscopy; Resonance; Temperature, Chemical uncouplers; Environmental conditions; High temperature; Oxidative phosphorylation; Physiological temperature; Red-laser excitation; Resonance enhancement; Resonance Raman spectroscopy, Laser excitation
Department/Centre:	Division of Biological Sciences > Biochemistry Division of Chemical Sciences > Inorganic & Physical Chemistry Division of Interdisciplinary Sciences > Centre for Biosystems Science and Engineering Division of Physical & Mathematical Sciences > Instrumentation Appiled Physics
Date Deposited:	23 Nov 2020 09:32
Last Modified:	23 Nov 2020 09:32
URI:	http://eprints.iisc.ac.in/id/eprint/66249

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