TY - JOUR

T1 - Small Sample Stress

T2 - Probing Oxygen-Deprived Ammonia-Oxidizing Bacteria with Raman Spectroscopy In Vivo

AU - Kniggendorf, Ann Kathrin

AU - Nogueira, Regina

AU - Bahmanabad, Somayeh Nasiri

AU - Pommerening-Röser, Andreas

AU - Roth, Bernhard Wilhelm

N1 - Funding Information: Funding: This research was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation), grant numbers 397827619 (Ann-Kathrin Kniggendorf) and 397827619 (Regina Nogueira). Bernhard Roth was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany’s Excellence Strategy within the Cluster of Excellence PhoenixD (EXC 2122, Project ID 390833453).

PY - 2020/3/19

Y1 - 2020/3/19

N2 - The stress response of ammonia-oxidizing bacteria (AOB) to oxygen deprivation limits AOB growth and leads to different nitrification pathways that cause the release of greenhouse gases. Measuring the stress response of AOB has proven to be a challenge due to the low growth rates of stressed AOB, making the sample volumes required to monitor the internal stress response of AOB prohibitive to repeated analysis. In a proof-of-concept study, confocal Raman microscopy with excitation resonant to the heme c moiety of cytochrome c was used to compare the cytochrome c content and activity of stressed and unstressed Nitrosomonas europaea (Nm 50), Nitrosomonas eutropha (Nm 57), Nitrosospira briensis (Nsp 10), and Nitrosospira sp. (Nsp 02) in vivo. Each analysis required no more than 1000 individual cells per sampling; thus, the monitoring of cultures with low cell concentrations was possible. The identified spectral marker delivered reproducible results within the signal-to-noise ratio of the underlying Raman spectra. Cytochrome c content was found to be elevated in oxygen-deprived and previously oxygen-deprived samples. In addition, cells with predominantly ferrous cytochrome c content were found in deprived Nitrosomonas eutropha and Nitrosospira samples, which may be indicative of ongoing electron storage at the time of measurement.

AB - The stress response of ammonia-oxidizing bacteria (AOB) to oxygen deprivation limits AOB growth and leads to different nitrification pathways that cause the release of greenhouse gases. Measuring the stress response of AOB has proven to be a challenge due to the low growth rates of stressed AOB, making the sample volumes required to monitor the internal stress response of AOB prohibitive to repeated analysis. In a proof-of-concept study, confocal Raman microscopy with excitation resonant to the heme c moiety of cytochrome c was used to compare the cytochrome c content and activity of stressed and unstressed Nitrosomonas europaea (Nm 50), Nitrosomonas eutropha (Nm 57), Nitrosospira briensis (Nsp 10), and Nitrosospira sp. (Nsp 02) in vivo. Each analysis required no more than 1000 individual cells per sampling; thus, the monitoring of cultures with low cell concentrations was possible. The identified spectral marker delivered reproducible results within the signal-to-noise ratio of the underlying Raman spectra. Cytochrome c content was found to be elevated in oxygen-deprived and previously oxygen-deprived samples. In addition, cells with predominantly ferrous cytochrome c content were found in deprived Nitrosomonas eutropha and Nitrosospira samples, which may be indicative of ongoing electron storage at the time of measurement.

KW - Confocal Raman microscopy

KW - Cytochrome c

KW - Nitrosomonas

KW - Nitrosospira

KW - Oxygen deprivation

KW - Resonance Raman spectroscopy

UR - http://www.scopus.com/inward/record.url?scp=85082670545&partnerID=8YFLogxK

U2 - 10.3390/microorganisms8030432

DO - 10.3390/microorganisms8030432

M3 - Article

AN - SCOPUS:85082670545

VL - 8

JO - Microorganisms

JF - Microorganisms

SN - 2076-2607

IS - 3

M1 - 432

ER -