Leibniz Institute of Photonic Technology, 07745, Jena, Germany.
Institute of Biodiversity, Friedrich Schiller University Jena, 07743, Jena, Germany.
Anal Bioanal Chem. 2022 Jan;414(1):601-611. doi: 10.1007/s00216-021-03541-y. Epub 2021 Jul 23.
Human activities have greatly increased the input of reactive nitrogen species into the environment and disturbed the balance of the global N cycle. This imbalance may be offset by bacterial denitrification, an important process in maintaining the ecological balance of nitrogen. However, our understanding of the activity of mixotrophic denitrifying bacteria is not complete, as most research has focused on heterotrophic denitrification. The aim of this study was to investigate substrate preferences for two mixotrophic denitrifying bacterial strains, Acidovorax delafieldii and Hydrogenophaga taeniospiralis, under heterotrophic, autotrophic or mixotrophic conditions. This complex analysis was achieved by simultaneous identification and quantification of H, O, CO, N, N and NO in course of the denitrification process with help of cavity-enhanced Raman spectroscopic (CERS) multi-gas analysis. To disentangle electron donor preferences for both bacterial strains, microcosm-based incubation experiments under varying substrate conditions were conducted. We found that Acidovorax delafieldii preferentially performed heterotrophic denitrification in the mixotrophic sub-experiments, while Hydrogenophaga taeniospiralis preferred autotrophic denitrification in the mixotrophic incubation. These observations were supported by stoichiometric calculations. The results demonstrate the prowess of advanced Raman multi-gas analysis to study substrate use and electron donor preferences in denitrification, based on the comprehensive quantification of complex microbial gas exchange processes.
人类活动大大增加了活性氮物种在环境中的输入，扰乱了全球氮循环的平衡。这种不平衡可能会被细菌反硝化所抵消，反硝化是维持氮生态平衡的重要过程。然而，我们对混合营养型反硝化细菌的活性的理解并不完全，因为大多数研究都集中在异养反硝化上。本研究的目的是在异养、自养或混合营养条件下，研究两种混合营养型反硝化细菌（ Acidovorax delafieldii 和 Hydrogenophaga taeniospiralis ）对底物的偏好。这种复杂的分析是通过腔增强拉曼光谱（ CERS ）多气体分析，在反硝化过程中同时识别和定量 H 、 O 、 CO 、 N 、 N 和 NO 来实现的。为了理清两种细菌对电子供体的偏好，在不同底物条件下进行了基于微宇宙的孵育实验。我们发现， Acidovorax delafieldii 在混合营养亚实验中优先进行异养反硝化，而 Hydrogenophaga taeniospiralis 在混合营养孵育中优先进行自养反硝化。这些观察结果得到了化学计量计算的支持。结果表明，先进的拉曼多气体分析在反硝化中具有研究底物利用和电子供体偏好的能力，这是基于对复杂微生物气体交换过程的全面定量。
