Global metabolomic responses of Nitrosomonas europaea 19718 to cold stress and altered ammonia feeding patterns

Type
Article

Authors
Lu, Huijie
Ulanov, Alexander V.
Nobu, Masaru
Liu, Wen-Tso

Online Publication Date
2015-11-05

Print Publication Date
2016-02

Date
2015-11-05

Abstract
© 2015 Springer-Verlag Berlin Heidelberg The model ammonia-oxidizing bacterium Nitrosomonas europaea represents one of the environmentally and biotechnologically significant microorganisms. Genome-based studies over the last decade have led to many intriguing discoveries about its cellular biochemistry and physiology. However, knowledge regarding the regulation of overall metabolic routes in response to various environmental stresses is limited due to a lack of comprehensive, time-resolved metabolomic analyses. In this study, gas chromatography–mass spectrometry (GC-MS)-based metabolic profiling was performed to characterize the temporal variations of N. europaea 19718 intercellular metabolites in response to varied temperature (23 and 10 °C) and ammonia feeding patterns (shock loading and continuous feeding of 20 mg N/L). Approximately 87 metabolites were successfully identified and mapped to the existing pathways of N. europaea 19718, allowing interpretation of the influence of temperature and feeding pattern on metabolite levels. In general, varied temperature had a more profound influence on the overall metabolism than varied feeding patterns. Total extracellular metabolite concentrations (relative to internal standards and normalized to biomass weight) were lower under cold stress and shock loading conditions compared with the control (continuous feeding at 23 °C). Cold stress caused the widespread downregulation of metabolites involved in central carbon metabolism, amino acid, and lipid synthesis (e.g., malonic acid, succinic acid, putrescine, and phosphonolpyruvate). Metabolites that showed differences under varied feeding patterns were mainly involved in nucleotide acid, amino acid, and lipid metabolism (e.g., adenine, uracil, and spermidine). This study highlighted the roles of central carbon and nitrogen metabolism in countering cold stress and altered ammonia availability. In addition, transcriptomic, proteomic, and metabolomic data from three studies on N. europaea were compared to achieve a holistic view of some important synergy and interconnectivity among different cellular components (RNA, protein, and metabolites) during ammonia starvation.

Citation
Lu H, Ulanov AV, Nobu M, Liu W-T (2015) Global metabolomic responses of Nitrosomonas europaea 19718 to cold stress and altered ammonia feeding patterns. Applied Microbiology and Biotechnology 100: 1843–1852. Available: http://dx.doi.org/10.1007/s00253-015-7095-y.

Acknowledgements
This study was supported by King Abdullah University of Science and Technology (KAUST, Thuwal, Saudi Arabia). Authors would like to thank Yifan He at the Department of Civil and Environmental Engineering, University of Illinois-Urbana Champaign for experimental assistance.

Publisher
Springer Nature

Journal
Applied Microbiology and Biotechnology

DOI
10.1007/s00253-015-7095-y

PubMed ID
26536877

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