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Finkel PL, Carrizo D, Rasmussen KR, Knudsen NAT, Parro V, Sánchez-García L. Lipid-based paleoecological and biogeochemical reconstruction of Store Saltsø, an extreme lacustrine system in SW Greenland. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 921:171199. [PMID: 38408664 DOI: 10.1016/j.scitotenv.2024.171199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 02/07/2024] [Accepted: 02/21/2024] [Indexed: 02/28/2024]
Abstract
Polar lakes harbour a unique biogeochemistry that reflects the implications of climatic fluctuations against a susceptible yet extreme environment. In addition to polar, Store Saltsø (Kangerlussuaq, southwestern Greenland) is an endorheic lake with alkaline and oligotrophic waters that host a distinctive ecology adapted to live in such particular physico-chemical and environmental conditions. By exploring the sedimentary record of Store Saltsø at a molecular and compound-specific isotopic level, we were able to understand its ecology and biogeochemical evolution upon climate change. We employed lipid biomarkers to identify biological sources and metabolic traits in different environmental samples (shore terrace, sediment core, and white precipitates at the shore), and their succession over time to reconstruct the lake paleobiology. Different molecular ratios and geochemical proxies provided further insights toward the evolution of environmental conditions in the frame of the deglaciation history of Kangerlussuaq. The relative abundance of terrestrial (i.e., plant derived) biomarkers (odd long-chain n-alkanes, even long-chain n-alkanols, and phytosterols) in the upper half of the shore terrace versus the relatively more present aquatic biomarkers (botryococcenes and long-chain alkenones) in its lower half revealed higher lake water levels in the past. Moreover, the virtual absence of organics in the deepest section of the sediment core (32-29 cm depth) suggested that the lake did not yet exist at the northwestern shore of Store Saltsø ∼5100 years ago. According to the relative abundance of lipid biomarkers detected in the adjacent section above (29-25 cm depth), we hypothesize that the northwestern shore of Store Saltsø formed ∼4900 years ago. By combining the molecular and compound-specific isotopic analysis of lipids in a ∼360 cm sedimentary sequence, we recreated the paleobiology and evolution of an extreme lacustrine environment suitable for the study of the limits of life and the effects of climate warming.
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Affiliation(s)
- Pablo L Finkel
- Centro de Astrobiología (CAB), CSIC-INTA, Madrid, Spain; Department of Physics and Mathematics, Department of Automatics, University of Alcalá, Madrid, Spain
| | | | | | | | - Victor Parro
- Centro de Astrobiología (CAB), CSIC-INTA, Madrid, Spain
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2
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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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Froning M, Grütering C, Blank LM, Hayen H. Determination of double bond positions in methyl ketones by gas chromatography-mass spectrometry using dimethyl disulfide derivatives. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2023; 37:e9457. [PMID: 36512472 DOI: 10.1002/rcm.9457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 12/12/2022] [Accepted: 12/12/2022] [Indexed: 06/17/2023]
Abstract
RATIONALE Methyl ketones are of interest for the application as biofuels. The fatty acid metabolism of different microbes has been rearranged to achieve a sustainable production of methyl ketones. The biofuel properties and possible further chemical modifications of these methyl ketones are influenced by their chain length, as well as their degree of saturation and the corresponding double bond position. METHODS A method based on gas chromatography-electron ionization; mass spectrometry (GC-EI-MS) was used to determine the double bond position of methyl ketones. Derivatization using dimethyl disulfide (DMDS) and an iodine catalyst enabled the activation of the double bonds for selective fragmentation during electron ionization. The cleavage led to key fragments in the Orbitrap high-resolution mass spectrum and allowed the unequivocal localization of the double bond position of the respective monounsaturated methyl ketone. RESULTS The double bond position of several medium chain length methyl ketones originating from the gram-negative bacterium Pseudomonas taiwanensis (P. taiwanensis) VLB120 was determined. The DMDS derivatives of methyl ketones can yield isobaric fragment ions for different possible double bond positions, which can be distinguished only using high-resolution MS. The double bond position of all methyl ketones deriving from P. taiwanensis VLB120 was the same, counting from the end of the aliphatic chain, and was determined as ω-7. CONCLUSIONS The derivatization of medium chain length monounsaturated methyl ketones with DMDS allowed the determination of the corresponding double bond position via GC-EI-MS. High-resolution MS is needed to differentiate possible double bond positions that yield isobaric fragment ions.
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Affiliation(s)
- Matti Froning
- Institute of Inorganic and Analytical Chemistry, University of Münster, Münster, Germany
| | - Carolin Grütering
- Institute of Applied Microbiology, Aachen Biology and Biotechnology, RWTH Aachen University, Aachen, Germany
| | - Lars M Blank
- Institute of Applied Microbiology, Aachen Biology and Biotechnology, RWTH Aachen University, Aachen, Germany
| | - Heiko Hayen
- Institute of Inorganic and Analytical Chemistry, University of Münster, Münster, Germany
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Xu L, Guan H, Liu L, Mao S, Feng J, Su Z, Liu L. Determining the double-bond positions of monounsaturated compounds in the alcohol fraction in seep carbonate. J Chromatogr A 2022; 1672:463009. [DOI: 10.1016/j.chroma.2022.463009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 03/26/2022] [Accepted: 03/29/2022] [Indexed: 10/18/2022]
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Eliason O, Segev E. Coccolith Sr/Ca is a robust temperature and growth rate indicator that withstands dynamic microbial interactions. GEOBIOLOGY 2022; 20:435-443. [PMID: 35048494 PMCID: PMC9305965 DOI: 10.1111/gbi.12487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 12/06/2021] [Accepted: 01/06/2022] [Indexed: 06/14/2023]
Abstract
Coccolithophores are a diverse group of calcifying microalgae that have left a prominent fossil record on Earth. Various coccolithophore relics, both organic and inorganic, serve as proxies for reconstruction of past oceanic conditions. Emiliania huxleyi is the most widely distributed representative of the coccolithophores in modern oceans and is known to engage in dynamic interactions with bacteria. Algal-bacterial interactions influence various aspects of algal physiology and alter algal alkenone unsaturation (UK'37 ), a frequently used organic coccolithophore-derived paleo-temperature proxy. Whether algal-bacterial interactions influence inorganic coccolithophore-derived paleo-proxies is yet unknown. A commonly used inorganic proxy for past productivity and sea surface temperature is the Sr/Ca ratio of the coccolith calcite. Interestingly, during interactions between bacteria and a population of calcifying algae, bacteria were shown to physically attach only to non-calcified algal cells, suggesting an influence on algal calcification. In this study, we explore the effects of algal-bacterial interactions on calcification and coccolith Sr/Ca ratios. We find that while bacteria attach only to non-calcified algal cells, coccolith cell coverage and overall calcite production in algal populations with and without bacteria is similar. Furthermore, we find that Sr/Ca values are impacted only by water temperature and algal growth rate, regardless of bacterial influences on algal physiology. Our observations reinforce the robustness of coccolith Sr/Ca ratios as a paleo-proxy independent of microbial interactions and highlight a fundamental difference between organic and inorganic paleo-proxies.
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Affiliation(s)
- Or Eliason
- Department of Plant and Environmental SciencesWeizmann Institute of ScienceRehovotIsrael
| | - Einat Segev
- Department of Plant and Environmental SciencesWeizmann Institute of ScienceRehovotIsrael
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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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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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Abstract
A number of technological challenges need to be overcome if algae are to be utilized for commercial fuel production. Current economic assessment is largely based on laboratory scale up or commercial systems geared to the production of high value products, since no industrial scale plant exits that are dedicated to algal biofuel. For macroalgae (‘seaweeds’), the most promising processes are anaerobic digestion for biomethane production and fermentation for bioethanol, the latter with levels exceeding those from sugar cane. Currently, both processes could be enhanced by increasing the rate of degradation of the complex polysaccharide cell walls to generate fermentable sugars using specifically tailored hydrolytic enzymes. For microalgal biofuel production, open raceway ponds are more cost-effective than photobioreactors, with CO2 and harvesting/dewatering costs estimated to be ~50% and up to 15% of total costs, respectively. These costs need to be reduced by an order of magnitude if algal biodiesel is to compete with petroleum. Improved economics could be achieved by using a low-cost water supply supplemented with high glucose and nutrients from food grade industrial wastewater and using more efficient flocculation methods and CO2 from power plants. Solar radiation of not <3000 h·yr−1 favours production sites 30° north or south of the equator and should use marginal land with flat topography near oceans. Possible geographical sites are discussed. In terms of biomass conversion, advances in wet technologies such as hydrothermal liquefaction, anaerobic digestion, and transesterification for algal biodiesel are presented and how these can be integrated into a biorefinery are discussed.
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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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Endo H, Hanawa Y, Araie H, Suzuki I, Shiraiwa Y. Overexpression of Tisochrysis lutea Akd1 identifies a key cold-induced alkenone desaturase enzyme. Sci Rep 2018; 8:11230. [PMID: 30046151 PMCID: PMC6060089 DOI: 10.1038/s41598-018-29482-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 07/12/2018] [Indexed: 12/28/2022] Open
Abstract
Alkenones are unusual long-chain neutral lipids that were first identified in oceanic sediments. Currently they are regarded as reliable palaeothermometers, since their unsaturation status changes depending on temperature. These molecules are synthesised by specific haptophyte algae and are stored in the lipid body as the main energy storage molecules. However, the molecular mechanisms that regulate the alkenone biosynthetic pathway, especially the low temperature-dependent desaturation reaction, have not been elucidated. Here, using an alkenone-producing haptophyte alga, Tisochrysis lutea, we show that the alkenone desaturation reaction is catalysed by a newly identified desaturase. We first isolated two candidate desaturase genes and found that one of these genes was drastically upregulated in response to cold stress. Gas chromatographic analysis revealed that the overexpression of this gene, named as Akd1 finally, increased the conversion of di-unsaturated C37-alkenone to tri-unsaturated molecule by alkenone desaturation, even at a high temperature when endogenous desaturation is efficiently suppressed. We anticipate that the Akd1 gene will be of great help for elucidating more detailed mechanisms of temperature response of alkenone desaturation, and identification of active species contributing alkenone production in metagenomic and/or metatranscriptomic studies in the field of oceanic biogeochemistry.
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Affiliation(s)
- Hirotoshi Endo
- Faculty of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8572, Japan
| | - Yutaka Hanawa
- Faculty of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8572, Japan
| | - Hiroya Araie
- Faculty of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8572, Japan.,College of Science and Engineering, Kanto Gakuin University, 1-50-1 Mutsuura-higashi, Kanazawa-ku, Yokohama, Kanagawa, 236-8501, Japan
| | - Iwane Suzuki
- Faculty of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8572, Japan
| | - Yoshihiro Shiraiwa
- Faculty of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8572, Japan.
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Cold-induced metabolic conversion of haptophyte di- to tri-unsaturated C 37 alkenones used as palaeothermometer molecules. Sci Rep 2018; 8:2196. [PMID: 29396545 PMCID: PMC5797101 DOI: 10.1038/s41598-018-20741-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 01/23/2018] [Indexed: 01/08/2023] Open
Abstract
The cosmopolitan marine haptophyte alga Emiliania huxleyi accumulates very long-chain (C37-C40) alkyl ketones with two to four trans-type carbon-carbon double bonds (alkenones). These compounds are used as biomarkers of haptophytes and as palaeothermometers for estimating sea-surface temperatures in biogeochemistry. However, the biosynthetic pathway of alkenones in algal cells remains enigmatic, although it is well known that the C37 tri-unsaturated alkenone (K37:3) becomes dominant at low temperatures, either by desaturation of K37:2 or by a separate pathway involving the elongation of tri-unsaturated alkenone precursors. Here, we present experimental evidence regarding K37:3 synthesis. Using the well-known cosmopolitan alkenone producer E. huxleyi, we labelled K37:2 with 13C by incubating cells with 13C-bicarbonate in the light at 25 °C under conditions of little if any K37:3 production. After stabilisation of the 13C-K37:2 level by depleting 13C-bicarbonate from the medium, the temperature was suddenly reduced to 15 °C. The 13C-K37:2 level rapidly decreased, and the 13C-K37:3 level increased, whereas the total 13C-K37 level—namely [K37:2 + K37:3]—remained constant. These 13C-pulse-chase-like experimental results indicate that 13C-K37:2 is converted directly to 13C-K37:3 by a desaturation reaction that is promoted by a cold signal. This clear-cut experimental evidence is indicative of the existence of a cold-signal-triggered desaturation reaction in alkenone biosynthesis.
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