Summary of study ST001198

This data is available at the NIH Common Fund's National Metabolomics Data Repository (NMDR) website, the Metabolomics Workbench, https://www.metabolomicsworkbench.org, where it has been assigned Project ID PR000807. The data can be accessed directly via it's Project DOI: 10.21228/M8CD73 This work is supported by NIH grant, U2C- DK119886.

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Study IDST001198
Study TitleTargeted LC-MS/MS Analysis of Soluble Metabolites in the MeOH:H2O Phase (part-IV)
Study SummaryCyanobacteria are a model photoautotroph and a chassis for the sustainable production of fuels and chemicals. Yet, knowledge of photoautotrophic metabolism in the natural environment of day/night cycles is lacking yet has implications for improved yield from plants, algae, and cyanobacteria. Here, a thorough approach to characterizing diverse metabolites—including carbohydrates, lipids, amino acids, pigments, co-factors, nucleic acids and polysaccharides—in the model cyanobacterium Synechocystis sp. PCC 6803 (S. 6803) under sinusoidal diurnal light-dark cycles was developed and applied. A custom photobioreactor and novel multi-platform mass spectrometry workflow enabled metabolite profiling every 30-120 minutes across a 24-hour diurnal sinusoidal LD (“sinLD”) cycle peaking at 1,600 mol photons m 2 s-1. We report widespread oscillations across the sinLD cycle with 90%, 94%, and 40% of the identified polar/semi-polar, non-polar, and polymeric metabolites displaying statistically significant oscillations, respectively. Microbial growth displayed distinct lag, biomass accumulation, and cell division phases of growth. During the lag phase, amino acids (AA) and nucleic acids (NA) accumulated to high levels per cell followed by decreased levels during the biomass accumulation phase, presumably due to protein and DNA synthesis. Insoluble carbohydrates displayed sharp oscillations per cell at the day-to-night transition. Potential bottlenecks in central carbon metabolism are highlighted. Together, this report provides a comprehensive view of photosynthetic metabolite behavior with high temporal resolution, offering insight into the impact of growth synchronization to light cycles via circadian rhythms. Incorporation into computational modeling and metabolic engineering efforts promises to improve industrially-relevant strain design.
Institute
Colorado State University
DepartmentChemical and Biological Engineering
Last NamePeebles
First NameChristie
Address700 Meridian Ave, Fort Collins, CO 80523
Emailchristie.peebles@colostate.edu
Phone970-491-6779
Submit Date2019-03-02
Raw Data AvailableYes
Raw Data File Type(s).cdf
Analysis Type DetailLC-MS
Release Date2019-07-17
Release Version1
Christie Peebles Christie Peebles
https://dx.doi.org/10.21228/M8CD73
ftp://www.metabolomicsworkbench.org/Studies/ application/zip

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Sample Preparation:

Sampleprep ID:SP001273
Sampleprep Summary:Briefly, 6 mL of 75% methanol (MeOH) was added to pellets, vortexed, and transferred to glass vials. 9 mL of 100% methyl tert-butyl ether (MTBE) was added, vortexed for 30 seconds, placed on automatic shaker for 1.5 hours at 4 ºC, and sonicated for 15 minutes. 3.75 mL of water was added, each extraction was vortexed by hand for 1 minute, and centrifuged for 10 minutes at 3,270g at 4ºC. A biphasic solution with a pellet formed: the top, green MTBE layer and the bottom, clear MeOH:H2O layer were separated into separate tubes and dried under N2,gas overnight. The pellet was stored at -80 ºC. After drying, the MTBE layer was resuspended in 100 uL 1:1 toluene:MeOH, transferred to a LC-MS vial insert, and stored at -80C for <1 month prior to MS analysis. The MeOH:H2O layer was resuspended in 1 mL of 1:1 H2O:MeOH, transferred to a 1.7 mL centrifuge tube and spun at 15,000g for 2 minutes at 4 ºC. The supernatant was split into two 465 µL aliquots—one for GCMS and one for LC(HILIC)MS—in glass vials and dried under N2,gas. The protocol outlined above is suitable for filter-quenched cyanobacteria samples and centrifuged cell pellets. The polar methanol/water fraction resulting from the biphasic extraction was processed for analysis by hydrophilic interaction liquid chromatography (HILIC) LC-MS. Dried samples were resuspended in 100 µL 1:1 H2O:MeOH and 10 µL were aliquoted into a pooled QC sample. Samples were stored at -80 ºC until analysis. The pooled QC sample was mixed and aliquoted into twelve vials. A QC injection was run every tenth injection. The dried polar fraction for analysis by GC-MS was stored at -80 ºC until derivatization, immediately prior to MS analysis. Samples were derivatized in 30 uL methoxyamine HCl and 30 uL MSTFA, as specified in the following section. Ten microliters were removed from each sample to create a pooled QC sample, mixed, and aliquoted into thirteen vials. A QC sample was run after every sixth injection. The non-polar MTBE phase was processed for non-targeted LC-MS analysis. Twenty microliters from each sample were pooled, mixed, and aliquoted into thirteen pooled QC samples. QC injections were placed after every sixth injection. An acid hydrolysis protocol was developed for identification of amino acids, nucleosides, and carbohydrates bound in insoluble pellet of protein, DNA/RNA, and polysaccharides, respectively. Pellets remaining from the biphasic extraction were removed from storage at -80 degrees C and residual solvent was evaporated under nitrogen gas. Pellets were re-suspended in 3 mL of 6 M hydrochloric acid (HCl) using vigorous vortexing and pipette re-suspension. The resulting suspension was a bright teal. The suspension was transferred equally two three separate glass vials for hydrolysis of the separate polymer constituents. Hydrolysis of proteins to amino acids was completed with a hydrochloric acid (HCl) hydrolysis, based on previously published protocols (Fountoulakis and Lahm 1998). Briefly, vials were incubated at 110 degrees C for with a loose cap seal. After 4 hours, the acid in each vial was entirely evaporated; 1 mL of 6 M HCl was added to each vial, vortexed, sealed tightly, and returned to 110 degrees C. After a total of 24 hours, vials were removed, and remaining acid was evaporated under nitrogen gas. Samples were resuspended in 150 µL of 1:1 MeOH:H2O, 20 uL was removed to create a pooled QC sample, the pooled QC was aliquoted into fourteen vials, and the solvent was evaporated under nitrogen gas. Amino acid samples were derivatized in 30 uL of methoxyamine HCl in pyridine and 30 uL of MTBSTFSA. The peak integration of each amino acid in each sample was manually checked and curated in the software Chromeleon™. Aspartic acid with 2- and 3-derivitization agent modifications were detected and summed for the total spectral abundance. Threonine with 2- and 3-derivitization agent modifications were detected and summed for the total spectral abundance. Polysaccharides and nucleic acid polymers were hydrolyzed to nucleosides using a modified protocol from Huang et al. (2012) (Huang, Kaiser, and Benner 2012). Briefly, vials were incubated at 130 degrees C for 10 minutes, removed and allowed to cool, and 100 uL was transferred to a glass teardrop vial. The remaining pellet was incubated at 160 degrees C for 40 minutes, removed and allowed to cool, re-suspended in 100 uL LC-MS grade water, vortexed for 15 seconds, centrifuged at 1,500g for 2 minutes, and the supernatant was transferred to the glass teardrop vial which contained purines from the 130 degree C incubation. The acid was evaporated under nitrogen gas. Samples were removed after the 10 minute 130ºC incubation to preserve purines (guanine and adenine) from degradation during the 40 minute 160ºC incubation.
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