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O’Neil GW, Keller A, Balila J, Golden S, Sipila N, Stone B, Nelson RK, Reddy CM. Monitoring Changes to Alkenone Biosynthesis in Commercial Tisochrysis lutea Microalgae. ACS OMEGA 2024; 9:16374-16383. [PMID: 38617607 PMCID: PMC11007839 DOI: 10.1021/acsomega.4c00087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 03/06/2024] [Accepted: 03/13/2024] [Indexed: 04/16/2024]
Abstract
Alkenones are unique lipids produced by certain species of microalgae, well-known for use in paleoclimatology, and more recently pursued to advance sustainability across multiple industries. Beginning in 2018, the biosynthesis of alkenones by commercially grown Tisochrysis lutea (T-Iso) microalgae from one of the world's most established producers, Necton S.A., changed dramatically from structures containing 37 and 38 carbons, to unusual shorter-chain C35 and C36 diunsaturated alkenones (C35:2 and C36:2 alkenones). While the exact reasons for this change remain unknown, analysis of alkenones isolated from T-Iso grown in 2021 and 2023 revealed that this change has persisted. The structure of these rare shorter-chain alkenones, including double bond position, produced by Necton T-Iso remained the same over the last five years, which was determined using a new and optimized cross-metathesis derivatization approach with analysis by comprehensive two-dimensional gas chromatography and NMR. However, noticeable differences in the alkenone profiles among the different batches were observed. Combined with fatty acid compositional analysis, the data suggest a connection between these lipid classes (e.g., increased DHA corresponds to lower amounts of shorter-chain alkenones) and the ability to manipulate their biosynthesis in T-Iso with changes to cultivation conditions.
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Affiliation(s)
- Gregory W. O’Neil
- Department
of Chemistry, Western Washington University, Bellingham, Washington 98225 (United States)
| | - Allison Keller
- Department
of Chemistry, Western Washington University, Bellingham, Washington 98225 (United States)
| | - Jazmine Balila
- Department
of Chemistry, Western Washington University, Bellingham, Washington 98225 (United States)
| | - Sydney Golden
- Department
of Chemistry, Western Washington University, Bellingham, Washington 98225 (United States)
| | - Nate Sipila
- Department
of Chemistry, Western Washington University, Bellingham, Washington 98225 (United States)
| | - Britton Stone
- Department
of Chemistry, Western Washington University, Bellingham, Washington 98225 (United States)
| | - Robert K. Nelson
- Department
of Marine Chemistry and Geochemistry, Woods
Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, United States
| | - Christopher M. Reddy
- Department
of Marine Chemistry and Geochemistry, Woods
Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, United States
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Liao S, Liu XL, Manz KE, Pennell KD, Novak J, Santos E, Huang Y. Comprehensive analysis of alkenones by reversed-phase HPLC-MS with unprecedented selectivity, linearity and sensitivity. Talanta 2023; 260:124653. [PMID: 37178676 DOI: 10.1016/j.talanta.2023.124653] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 05/03/2023] [Accepted: 05/04/2023] [Indexed: 05/15/2023]
Abstract
Alkenones are among the most widely used paleotemperature biomarkers. Traditionally, alkenones are analyzed using gas chromatography-flame ionization detector (GC-FID), or GC-chemical ionization-mass spectrometry (GC-CI-MS). However, these methods encounter considerable challenges for samples that exhibit matrix interference or low concentrations, with GC-FID requiring tedious sample preparations and GC-CI-MS suffering from nonlinear response and a narrow linear dynamic range. Here we demonstrate that reversed-phase high pressure liquid chromatography-mass spectrometry (HPLC-MS) methods provide excellent resolution, selectivity, linearity and sensitivity for alkenones in complex matrices. We systematically compared the advantages and limitations of three mass detectors (quadrupole, Orbitrap, and quadrupole-time of flight) and two ionization modes (electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI)) for alkenone analyses. We demonstrate that ESI performs better than APCI as response factors of various unsaturated alkenones are similar. Among the three mass analyzers tested, orbitrap MS provided the lowest limit of detection (0.4, 3.8 and 8.6 pg injected masses for Orbitrap, qTOF and single quadrupole MS, respectively) and the widest linear dynamic range (600, 20 and 30 folds for Orbitrap, qTOF and single quadrupole MS, respectively). Single quadrupole MS operated in ESI mode provides accurate quantification of proxy measurements over a wide range of injection masses, and with its modest instrument cost, represents an ideal method for routine applications. Analysis of global core-top sediment samples confirmed the efficacy of HPLC-MS methods for the detection and quantification of paleotemperature proxies based on alkenones and their superiority over GC-based methods. The analytical method demonstrated in this study should also allow highly sensitive analyses of diverse aliphatic ketones in complex matrices.
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Affiliation(s)
- Sian Liao
- Department of Chemistry, Brown University, 324 Brook Street, Providence, RI, 02912, USA
| | - Xiao-Lei Liu
- School of Geosciences, University of Oklahoma, 100 E. Boyd Street, Norman, OK, 73019, USA
| | - Katherine E Manz
- School of Engineering, Brown University, 345 Brook Street, Providence, RI, 02912, USA
| | - Kurt D Pennell
- School of Engineering, Brown University, 345 Brook Street, Providence, RI, 02912, USA
| | - Joseph Novak
- Ocean Sciences Department, University of California, Santa Cruz, CA, 95064, USA
| | - Ewerton Santos
- Department of Earth, Environmental and Planetary Sciences, Brown University, 324 Brook Street, Providence, RI, 02912, USA
| | - Yongsong Huang
- Department of Earth, Environmental and Planetary Sciences, Brown University, 324 Brook Street, Providence, RI, 02912, USA.
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3
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Liao S, Huang Y. Preferential formation of mono‐dimethyl disulfide adducts for determining double bond positions of poly‐unsaturated fatty acids. J AM OIL CHEM SOC 2022. [DOI: 10.1002/aocs.12561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Sian Liao
- Department of Chemistry Brown University Providence Rhode Island USA
- Institute at Brown for Environment and Society Brown University Providence Rhode Island USA
| | - Yongsong Huang
- Department of Earth, Environmental and Planetary Sciences Brown University Providence Rhode Island USA
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4
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Liao S, Sherman G, Huang Y. Elucidation of double-bond positions of polyunsaturated alkenes through gas chromatography/mass spectrometry analysis of mono-dimethyl disulfide derivatives. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2022; 36:e9228. [PMID: 34845773 DOI: 10.1002/rcm.9228] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2021] [Revised: 10/24/2021] [Accepted: 11/22/2021] [Indexed: 06/13/2023]
Abstract
RATIONALE Derivatization with dimethyl disulfide (DMDS) followed by gas chromatography/mass spectrometry (GC/MS) analysis is a well-established method for locating double-bond position on the alkyl chain of mono-unsaturated compounds such as alkenes. For alkenes containing more than one double bond, however, the conventional DMDS derivatization approach forms poly- or cyclized DMDS adducts whose mass spectra are difficult to interpret in terms of double-bond positions. In this study, we report an efficient experimental procedure to produce mono-DMDS adducts for polyunsaturated alkenes with two to six double bonds. GC/MS analyses of these mono-DMDS adducts yield highly characteristic mass fragments, allowing unambiguous assignments of double-bond positions on the alkyl chain. We also apply our new approach (i.e., preferential formation of mono-DMDS adducts during derivatization with DMDS) to determine the double-bond positions of unsaturated alkenes produced by laboratory cultured Isochrysis litoralis, a haptophyte algal species. METHODS Alkenes from different sources were derivatized with DMDS at 25°C for 20 to 160 min. The mass spectra of mono-DMDS adducts were obtained by GC/EI-MS analysis of reaction products which contain chromatographically resolved mono-DMDS adducts. RESULTS Mass spectra of corresponding mono-DMDS adducts contain prominent diagnostic ions that allow a conclusive elucidation of double-bond positions. In culture samples of Isochrysis litoralis, a series of novel mono- to tri-unsaturated C31 alkenes (9-C31:1 , 6,9-C31:2 , 6,22-C31:2 , 6,25-C31:2 , 9,22-C31:2 , 6,9,25-C31:3 ) were discovered for the first time. CONCLUSIONS A highly efficient DMDS derivatization approach is developed to yield abundant mono-DMDS adducts of polyunsaturated alkyl alkenes for elucidating double-bond positions using GC/MS.
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Affiliation(s)
- Sian Liao
- Department of Chemistry, Brown University, Providence, RI, USA
- Institute at Brown for Environment and Society, Brown University, Providence, RI, USA
| | - Gordon Sherman
- Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI, USA
| | - Yongsong Huang
- Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI, USA
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O'Neil GW, Gale AC, Nelson RK, Dhaliwal HK, Reddy CM. Unusual
Shorter‐Chain C
35
and
C
36
Alkenones from Commercially Grown
Isochrysis
sp. Microalgae. J AM OIL CHEM SOC 2021. [DOI: 10.1002/aocs.12481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Gregory W. O'Neil
- Department of Chemistry Western Washington University Bellingham WA 98225 USA
| | - Amanda C. Gale
- Department of Chemistry Western Washington University Bellingham WA 98225 USA
| | - Robert K. Nelson
- Department of Marine Chemistry and Geochemistry Woods Hole Oceanographic Institution Woods Hole MA 02543 USA
| | - Herman K. Dhaliwal
- Department of Chemistry Western Washington University Bellingham WA 98225 USA
| | - Christopher M. Reddy
- Department of Marine Chemistry and Geochemistry Woods Hole Oceanographic Institution Woods Hole MA 02543 USA
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Liao S, Dillon JT, Huang C, Santos E, Huang Y. Silver (I)-dimercaptotriazine functionalized silica: A highly selective liquid chromatography stationary phase targeting unsaturated molecules. J Chromatogr A 2021; 1645:462122. [PMID: 33853010 DOI: 10.1016/j.chroma.2021.462122] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Revised: 03/25/2021] [Accepted: 03/28/2021] [Indexed: 11/26/2022]
Abstract
Silver(I)-mercaptopropyl (Ag-MP) functionalized silica gel has demonstrated its effectiveness in separating various unsaturated organic compounds including unsaturated fatty acid ethyl esters (FAEEs), triglycerols (TAGs) and long-chain alkyl ketones (alkenones). While Ag-MP stationary phase displays many advantages over the conventional silver ion-impregnated silica gel (e.g., stability, high recovery, etc.), potential drawbacks of Ag-MP include relatively low retentions for unsaturated molecules, which could limit chromatographic resolutions under certain circumstances. In this study, we evaluate a new silver-thiolate stationary phase: silver(I)-dimercaptotriazine (Ag-DMT) functionalized silica gel targeting the separation of unsaturated compounds. We show Ag-DMT affords substantially higher retention factors, peak resolutions and capacities for TAGs and FAEEs than Ag-MP does. Ag-DMT also yields higher purity eicosapentaenoic acid (EPA) from fish oil FAEE mixtures than Ag-MP. In addition, Ag-DMT resolves double bond positional and cis/trans-isomers of C18:1 fatty acid methyl esters (FAMEs) as well as unsaturated methyl/ethyl alkenones with different number of double bonds. Based on van't Hoff plots, enthalpy changes during the adsorption of unsaturated FAEEs onto Ag-DMT are ~2 times higher than those on Ag-MP. Such difference may be attributed to the stronger electron-withdrawing effect of the thiol group on DMT, which results in more positively charged silver ions hence greater interactions with unsaturated molecules. The stronger interaction between double bonds and Ag-DMT is further corroborated by density-functional theory (DFT) calculations. Ag-DMT shows its high stability for repeated uses in the separation of TAGs over 319 runs, with peak resolutions decreasing by < 3%. Collectively, our data demonstrate the exceptionally high efficiency of Ag-DMT column for separating unsaturated molecules.
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Affiliation(s)
- Sian Liao
- Department of Chemistry, Brown University, 324 Brook Street, Providence, Rhode Island 02912, USA
| | - James T Dillon
- Department of Chemistry, Brown University, 324 Brook Street, Providence, Rhode Island 02912, USA
| | - Cancan Huang
- Department of Chemistry, Brown University, 324 Brook Street, Providence, Rhode Island 02912, USA
| | - Ewerton Santos
- Department of Earth, Environmental and Planetary Sciences, Brown University, 324 Brook Street, Providence, Rhode Island 02912, USA
| | - Yongsong Huang
- Department of Earth, Environmental and Planetary Sciences, Brown University, 324 Brook Street, Providence, Rhode Island 02912, USA.
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An efficient approach to eliminate steryl ethers and miscellaneous esters/ketones for gas chromatographic analysis of alkenones and alkenoates. J Chromatogr A 2019; 1596:175-182. [DOI: 10.1016/j.chroma.2019.02.064] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 02/25/2019] [Accepted: 02/27/2019] [Indexed: 11/19/2022]
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8
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Zheng Y, Dillon JT, Zhang Y, Huang Y. Discovery of alkenones with variable methylene-interrupted double bonds: implications for the biosynthetic pathway. JOURNAL OF PHYCOLOGY 2016; 52:1037-1050. [PMID: 27573587 DOI: 10.1111/jpy.12461] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 07/23/2016] [Indexed: 06/06/2023]
Abstract
Alkenones (C37 -C40 ) are highly specific biomarkers produced by certain haptophyte algae in ocean and lacustrine environments and have been widely used for paleoclimate studies. Unusual shorter-chain alkenones (SCA; e.g., C35 and C36 ) have been found in environmental and culture samples, but the origin and structure of these compounds are much less understood. The marine alkenone producer, Emiliania huxleyi CCMP2758 strain, was reported with abundant C35:2 Me (∆12, 19 ) alkenones when cultured at 15°C (Prahl et al. 2006). Here we show, when this strain is cultured at 4°C-10°C, that CCMP2758 produces abundant C35:3 Me, C36:3 Me, and small amounts of C36:3 Et alkenones with unusual double-bond positions of ∆7, 12, 19 . We determine the double-bond positions of the C35:3 Me and C36:3 Me alkenones by GC-MS analysis of the dimethyl disulfide and cyclobutylamine derivatives, and we provide the first temperature calibrations based on the unsaturation ratios of the C35 and C36 alkenones. Previous studies have found C35:2 Me (∆14, 19 ) and C36:2 Et (∆14, 19 ) alkenones with three-methylene interruption in the Black Sea sediments, but this is the first reported instance of alkenones with a mixed three- and five-methylene interruption configuration in the double-bond positions. The discovery of these alkenones allows us to propose a novel biosynthetic scheme, termed the SCA biosynthesis pathway, that simultaneously rationalizes the formation of both the C35:3 Me (∆7, 12, 19 ) alkenone in our culture and the ∆14, 19 Black Sea type alkenones without invoking new desaturases for the unusual double-bond positions.
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Affiliation(s)
- Yinsui Zheng
- Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, Rhode Island, 02912, USA
| | - James T Dillon
- Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, Rhode Island, 02912, USA
| | - Yifan Zhang
- Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, Rhode Island, 02912, USA
| | - Yongsong Huang
- Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, Rhode Island, 02912, USA
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