Kniggendorf Ann-Kathrin, Nogueira Regina, Nasiri Bahmanabad Somayeh, Pommerening-Röser Andreas, Roth Bernhard Wilhelm
Hannover Centre for Optical Technologies, Gottfried Wilhelm Leibniz University of Hannover, Nienburger Str. 17, 30167 Hannover, Germany.
Institute for Sanitary Engineering and Waste Management, Gottfried Wilhelm Leibniz Universität Hannover, Welfengarten 1, 30167 Hannover, Germany.
Microorganisms. 2020 Mar 19;8(3):432. doi: 10.3390/microorganisms8030432.
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 (Nm 50), (Nm 57), (Nsp 10), and 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 and samples, which may be indicative of ongoing electron storage at the time of measurement.
氨氧化细菌（AOB）对缺氧的应激反应限制了AOB的生长，并导致不同的硝化途径，进而造成温室气体的排放。由于应激状态下AOB的生长速率较低，测量AOB的应激反应已被证明是一项挑战，这使得监测AOB内部应激反应所需的样本量对于重复分析来说过高。在一项概念验证研究中，利用激发与细胞色素c的血红素c部分共振的共聚焦拉曼显微镜，在体内比较了应激和未应激的嗜硝化亚硝化单胞菌（Nm 50）、嗜硝化亚硝化单胞菌（Nm 57）、欧洲亚硝化单胞菌（Nsp 10）和亚硝化螺菌属（Nsp 02）的细胞色素c含量和活性。每次分析每个样本所需的单个细胞不超过1000个；因此，可以监测低细胞浓度的培养物。所确定的光谱标记在基础拉曼光谱的信噪比范围内给出了可重复的结果。发现在缺氧和先前缺氧的样本中细胞色素c含量升高。此外，在缺氧的嗜硝化亚硝化单胞菌和欧洲亚硝化单胞菌样本中发现主要含有亚铁细胞色素c的细胞，这可能表明在测量时正在进行电子储存。
