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Expanded Utility of Signature Lipid Biomarker Analysis for Microbial Community Composition and Nutritional/Physiological Status with HPLC/ESI/MS/MS Analysis of Intact Lipid Components.
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Expanded Utility of Signature Lipid Biomarker Analysis for Microbial Community Composition and Nutritional/Physiological Status with HPLC/ESI/MS/MS Analysis of Intact Lipid Components • David C. White, Cory Lytle, Sarah J. Macnaughton, John R. Stephen, Aaron Peacock, Carol A. Smith, Ying Dong Gan,Yun-Juan Chang, Yevette M. Piceno • Center for Environmental Biotechnology, University of Tennessee, Knoxville, TN, Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, Microbial Insights, Inc., Rockford, TN, Microbial Insights, Inc. -CEB
In-situ Microbial Community Assessment In the Environment < 1.0 to 0.1% of the in-situ microbial community is detected using Isolation and Classical Plate Count Many non-culturable organisms can be infectious (VNCB), isolation can take days, lose insight into community interactions & physiology Two Complimentary Biomarker Methods: DNA: Recover from surface, Amplify with PCR using rDNA primers , Separate with denaturing gradient gel electrophoresis (DGGE), sequence for identification and phylogenetic relationship. Great specificity Lipids: Extract, concentrate, structural analysis Quantitative, Insight into: viable biomass, community composition, Nutritional-physiological status, evidence for metabolic activity
Signature Lipid Biomarker Analysis Cathedral from a Brick Predict impact of Cr contamination (from 50-200,000 ppm) on soil microbial community by artificial neural network (ANN) analysis PLFA (phospholipid fatty acid) excellent ~x 102-103 ppm Cr with (PLFA). DNA is “non compressible” ~ perfect code not so influenced By microniche conditions as cell membranes PLFA is compressible as contains physiological status input Contains “holistic’ information & responds to perturbations Predict it is a Cathedral or a Prison : DNA a perfect brick PLFA a non-linear mixture of bricks and a window
Signature Lipid Biomarker Analysis • Phospholipid Fatty Acid [PLFA] Biomarker Analysis = Single most quantitative, comprehensive insight into in-situ microbial community • Why not Universally utilized? • Requires 8 hr extraction with ultrapure solvents [emulsions]. • Ultra clean glassware [incinerated 450oC]. • Fractionation of Polar Lipids • Derivatization [transesterification] • 5. GC/MS analysis ~ picomole detection ~ 104 cells LOD • 6. Arcane Interpretation [Scattered Literature] • 7. 3-4 Days and ~ $250
Signature Lipid Biomarker Analysis Expand the Lipid Biomarker Analysis 1. Increase speed and recovery of extraction “Flash” 2. Include new lipids responsive to physiological status HPLC (not need derivatization & increase molecular size) Respiratory quinone ~ redox & terminal electron acceptor Diglyceride ~ cell lysis Archea ~ methanogens Lipid ornithine ~ bioavailable phosphate Lysyl-phosphatidyl glycerol ~ low pH Poly beta-hydroxy alkanoate ~ unbalanced growth 3. Increased Sensitivity and Specificity ESI/MS/MS
Lyophilized Soil Fractions, Pipe Biofilm 1. Neutral Lipids SFECO2 UQ isoprenologues ESE Chloroform.methanol Derivatize –N-methyl pyridyl Diglycerides Sterols Ergostrerol Cholesterol 2. Polar Lipids Transesterify PLFA Intact Lipids Phospholipids PG, PE, PC, Cl, & sn1 sn2 FA Amino Acid PG Ornithine lipid Archea ether lipids Plamalogens 3. In-situ Derivatize in SFECO2 CG/MS PHA Thansesterify & Derivatize N-methyl pyridyl 2,6 DPA (Spores) LPS-Amide OH FA HPLC/ESI/MS/MS
Lipid Biomarker Analysis Sequential High Pressure/Temperature Extraction (~ 1 Hour) Supercritical CO2 + Methanol enhancer Neutral Lipids, (Sterols, Diglycerides, Ubiquinones) Lyses Cells Facilitates DNA Recovery (for off-line analysis 2. Polar solvent Extraction Phospholipids CID detect negative ions Plasmalogens Archeal Ethers 3). In-situ Derivatize & Extract Supercritical CO2 + Methanol enhancer 2,6 Dipicolinic acid Bacterial Spores Amide-Linked Hydroxy Fatty acids [Gram-negative LPS] Three Fractions for HPLC/ESI/MS/MS Analysis
Feasibility of “Flash” Extraction ASE vs B&D solvent extraction* Bacteria = B&D, no distortion Fungal Spores = 2 x B&D Bacterial Spores = 3 x B&D Eukaryotic = 3 x polyenoic FA [2 cycles 80oC, 1200 psi, 20 min] vs B&D = 8 -14 Hours *Macnaughton, S. J., T. L. Jenkins, M. H. Wimpee, M. R. Cormier, and D. C. White. 1997. Rapid extraction of lipid biomarkers frompure culture and environmental samples using pressurized accelerated hot solvent extraction. J. Microbial Methods 31: 19-27(1997) CEB Microbial Insights, Inc.
ESI (cone voltage) Q-1 CID Q-3 FRAGMENTATION with ESI/MS/MS
Respiratory Ubiquinone (UQ) Gram-negative Bacteria with Oxygen as terminal acceptor LOQ = 225 femtomole/uL, LOD = 75 femtomole/uL ~ 100E. coli Isocratic 95.5/4.5 % methanol/aqueous 1 mM ammonium acetate Q7 Q10 Q6 197 m/z
Pyridinium Derivative of 1, 2 Dipalmitin [M+92-109]+ M = mass of original Diglyceride LOD ~100 attomoles/ uL [M+92]+
LIPID Biomarker Analysis 1. Intact Membranes essential for Earth-based life 2. Membranes contain Phospholipids 3. Phospholipids have a rapid turnover from endogenous phospholipases . 4. Sufficiently complex to provide biomarkers for viable biomass, community composition, nutritional/physiological status 5. Analysis with extraction provides concentration & purification 6. Structure identifiable by Electrospray Ionization Mass Spectrometry at attomoles/uL (near single bacterial cell) 7. Surface localization, high concentration ideal for organic SIMS mapping localization
Membrane Liability (turnover) VIABLE NON-VIABLE O O || || H2COC H2COC O O phospholipase | | || || cell death C O CH C O CH | O | || H2 C O H H2 C O P O CH2CN+ H3 | Neutral lipid, ~DGFA O- Polar lipid, ~ PLFA
PE PE PG A PC PG B Separation on HAISIL reverse phase HL C-18 column, 30 mm x 1mm x 3 μ, 95/5 methanol + 0.002% piperidine/water 50 μL/min, post-column modifier 0.02% piperidine in methanol, 10 μL/min. PE C (A) Chromatogram of purified brain and egg yolk derived authentic PG, PE, and PC; (B) Extracted ion chromatogram (EIC) of PG from soil containing 15:0, 16:0, 16:1, 17:0, 17:1, 18:1, 19:1 (see Fig 5); (C) EIC for ions diagnostic of PE from the soil used in B.
Parent product ion MS/MS of synthetic PG Q-1 1ppm PG scan m/z 110-990 (M –H) - Sn1 16:0, Sn2 18:2 Q-3 product ion scan of m/z 747scanned m/z 110-990 Note 50X > sensitivity SIM additional 5x > sensitivity ~ 250X
Detection of specific per 13C-labeled bacteria added to soils Extract lipids, HPLC/ESI/MS/MS analysis of phospholipids detect specific PLFA as negative ions PLFA 12C Per 13C 16:1 253 269 same as 12C 17:0 16:0 255 271 Unusual 12C 17:0 (269) + 2 13C cy17:0 267 284 12C 18:0 (283) + 13C 18:1 281 29912C 20:6 , 12C 19:0 with 2 13C 19:1 295 314 12C 21:5 (315), 12C 21:6 (313) 13C bacteria added No 13C bacteria added
Archaebacterial Tetraether Lipid FW 1640.4 In sim LOQ ~ 50 ppb ES+ [M-2H+Na+K]+ [M+H]+
ESI Spectrum of 2, 6-Dimethyl Dipicolinate LOD ~ 103 spores ~ 0.5 femtomoles/ul [M+H]+ ES+ Mobile phase: MeOH + 1mM ammonium acetate Cone: 40V [M+Na]+
Lipid Biomarker Analysis Expanded Lipid Analysis Greatly Increase Specificity ~ Electrospray Ionization ( Cone voltage between skimmer and inlet ) In-Source Collision-induced dissociation (CID) Tandem Mass Spectrometry Scan Q-1 CID* Q-3 Difference Daughter ion Fix Vary Vary Parent ion Vary Fix Vary Neutral loss Vary Vary Fix Neutral gain Vary Vary Fix Select-ion monitoring Fix Fix Fix *Collision-induced dissociation (CID) is a reaction region between quadrupoles
Tandem Mass Spectrometers Ion trap MSn (Tandem in Time) Smaller, Least Expensive, >Sensitive (full scan) Quadrupole/TOF > Mass Range, > Resolution MS/CAD/MS (Tandem in Space) 1. True Parent Ion Scan to Derivative Ion Scan 2. True Neutral Loss Scan 3. Generate Neutral Gain Scan 4. More Quantitative 5. > Sensitivity for SIM 6. > Dynamic Range Microbial Insights, Inc. CEB
Problem: Rapid Detection/Identification of Microbes Propose a Sequential High Pressure/Temperature Extractor Delivers Three Analytes to HPLC/ESI/MS/MS