title: Evaluation and characterization of bacterial metabolic dynamics with a novel profiling technique, real-time metabolotyping.
abstract: BACKGROUND
  Environmental processes in ecosystems are dynamically altered by several metabolic responses in microorganisms, including intracellular sensing and pumping, battle for survival, and supply of or competition for nutrients. Notably, intestinal bacteria maintain homeostatic balance in mammals via multiple dynamic biochemical reactions to produce several metabolites from undigested food, and those metabolites exert various effects on mammalian cells in a time-dependent manner. We have established a method for the analysis of bacterial metabolic dynamics in real time and used it in combination with statistical NMR procedures.
  
  
  RESULTS
  We developed a novel method called real-time metabolotyping (RT-MT), which performs sequential (1)H-NMR profiling and two-dimensional (2D) (1)H, (13)C-HSQC (heteronuclear single quantum coherence) profiling during bacterial growth in an NMR tube. The profiles were evaluated with such statistical methods as Z-score analysis, principal components analysis, and time series of statistical TOtal Correlation SpectroScopY (TOCSY). In addition, using 2D (1)H, (13)C-HSQC with the stable isotope labeling technique, we observed the metabolic kinetics of specific biochemical reactions based on time-dependent 2D kinetic profiles. Using these methods, we clarified the pathway for linolenic acid hydrogenation by a gastrointestinal bacterium, Butyrivibrio fibrisolvens. We identified trans11, cis13 conjugated linoleic acid as the intermediate of linolenic acid hydrogenation by B. fibrisolvens, based on the results of (13)C-labeling RT-MT experiments. In addition, we showed that the biohydrogenation of polyunsaturated fatty acids serves as a defense mechanism against their toxic effects.
  
  
  CONCLUSIONS
  RT-MT is useful for the characterization of beneficial bacterium that shows potential for use as probiotic by producing bioactive compounds.
authors.affiliation: RIKEN Research Center for Allergy and Immunology, Yokohama, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Fukuda
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Nakanishi
authors.forename: Eisuke
authors.initials: E
authors.lastname: Chikayama
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ohno
authors.forename: Tsuneo
authors.initials: T
authors.lastname: Hino
authors.forename: Jun
authors.initials: J
authors.lastname: Kikuchi
mesh_terms: D045856:Butyrivibrio / Q000378:metabolism*; D006706:Homeostasis; D006859:Hydrogen / Q000378:metabolism; D019787:Linoleic Acid / Q000378:metabolism; D019906:Nuclear Magnetic Resonance, Biomolecular
chemical_list: D006859:Hydrogen; D019787:Linoleic Acid