Niederrhein University of Applied Sciences, Microbiology and Food Hygiene, Mönchengladbach, Germany.
Environ Technol. 2009 Nov;30(12):1281-9. doi: 10.1080/09593330903055635.
Over the last decade X-ray absorption near edge structure (XANES) spectroscopy has been used in an increasing number of microbiological studies. In addition to other applications it has served as a valuable tool for the investigation of the sulphur globules deposited intra- or extracellularly by certain photo- and chemotrophic sulphur-oxidizing (Sox) bacteria. For XANES measurements, these deposits can easily be concentrated by filtration or sedimentation through centrifugation. However, during oxidative metabolism of reduced sulphur compounds, such as sulphide or thiosulphate, sulphur deposits are not the only intermediates formed. Soluble intermediates such as sulphite may also be produced and released into the medium. In this study, we explored the potential of XANES spectroscopy for the detection and speciation of sulphur compounds in culture supernatants of the phototrophic purple sulphur bacterium Allochromatium vinosum. More specifically, we investigated A. vinosum DeltasoxY, a strain with an in frame deletion of the soxY gene. This gene encodes an essential component of the thiosulphate-oxidizing Sox enzyme complex. Improved sample preparation techniques developed for the DeltasoxY strain allowed for the first time not only the qualitative but also the quantitative analysis of bacterial culture supernatants by XANES spectroscopy. The results thus obtained verified and supplemented conventional HPLC analysis of soluble sulphur compounds. Sulphite and also oxidized organic sulphur compounds were shown by XANES spectroscopy to be present, some of which were not seen when standard HPLC protocols were used.
在过去的十年中，X 射线吸收近边结构（XANES）光谱学在越来越多的微生物研究中得到了应用。除了其他应用外，它还作为一种有价值的工具，用于研究某些光和化学硫氧化（Sox）细菌在细胞内或细胞外沉积的硫球。对于 XANES 测量，这些沉积物可以通过过滤或离心沉淀很容易地浓缩。然而，在还原硫化合物（如硫化物或硫代硫酸盐）的氧化代谢过程中，硫沉积物并不是唯一形成的中间体。可溶性中间体，如亚硫酸盐，也可能产生并释放到培养基中。在这项研究中，我们探索了 XANES 光谱学在检测和特定化培养上清液中硫化合物的潜力，研究对象是光养紫色硫细菌 Allochromatium vinosum。更具体地说，我们研究了 A. vinosum DeltasoxY，这是一种 SoxY 基因缺失的菌株。该基因编码硫代硫酸盐氧化 Sox 酶复合物的必需成分。为 DeltasoxY 菌株开发的改进的样品制备技术首次不仅允许通过 XANES 光谱学对细菌培养上清液进行定性分析，还允许进行定量分析。由此获得的结果验证并补充了可溶性硫化合物的常规 HPLC 分析。XANES 光谱学表明，亚硫酸盐和氧化有机硫化合物存在，而当使用标准 HPLC 方案时，其中一些则没有被观察到。
