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Evans BR, Foston M, O'Neill HM, Reeves D, Rempe C, McGrath K, Ragauskas AJ, Davison BH. Production of deuterated biomass by cultivation of Lemna minor (duckweed) in D 2O. PLANTA 2019; 249:1465-1475. [PMID: 30697645 DOI: 10.1007/s00425-019-03097-3] [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: 11/07/2018] [Accepted: 01/21/2019] [Indexed: 06/09/2023]
Abstract
Common duckweed Lemna minor was cultivated in 50% D2O to produce biomass with 50-60% deuterium incorporation containing cellulose with degree of polymerization close (85%) to that of H2O-grown controls. The small aquatic plant duckweed, particularly the genus Lemna, widely used for toxicity testing, has been proposed as a potential source of biomass for conversion into biofuels as well as a platform for production of pharmaceuticals and specialty chemicals. Ability to produce deuterium-substituted duckweed can potentially extend the range of useful products as well as assist process improvement. Cultivation of these plants under deuterating conditions was previously been reported to require addition of kinetin to induce growth and was hampered by anomalies in cellular morphology and protein metabolism. Here, we report the production of biomass with 50-60% deuterium incorporation by long-term photoheterotrophic growth of common duckweed Lemna minor in 50% D2O with 0.5% glucose. L. minor grown in 50% D2O without addition of kinetin exhibited a lag phase twice that of H2O-grown controls, before start of log phase growth at 40% of control rates. Compared to continuous white fluorescent light, growth rates increased fivefold for H2O and twofold for 50% D2O when plants were illuminated at higher intensity with a metal halide lamp and a diurnal cycle of 12-h light/12-h dark. Deuterium incorporation was determined by a combination of 1H and 2H nuclear magnetic resonance (NMR) to be 40-60%. The cellulose from the deuterated plants had an average-number degree of polymerization (DPn) and polydispersity index (PDI) close to that of H2O-grown controls, while Klason lignin content was reduced. The only major gross morphological change noted was root inhibition.
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Affiliation(s)
- Barbara R Evans
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
| | - Marcus Foston
- Institute of Paper Science and Technology, School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332, USA
- Department of Energy, Environmental and Chemical Engineering, Washington University, St. Louis, MO, 63130, USA
| | - Hugh M O'Neill
- Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - David Reeves
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
- Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville, TN, 37996, USA
| | - Caroline Rempe
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
- School of Genome Science and Technology, F337 Walters Life Science, University of Tennessee, Knoxville, 37996, TN, USA
| | - Kathi McGrath
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
- Sierra Vista High School, Las Vegas, NV, USA
| | - Arthur J Ragauskas
- Institute of Paper Science and Technology, School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332, USA
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN, 37996, USA
| | - Brian H Davison
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
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Abstract
Soon after the discovery of deuterium, efforts to utilize this stable isotope of hydrogen for labeling of plants began and have proven successful for natural abundance to 20% enrichment. However, isotopic labeling with deuterium ((2)H) in higher plants at the level of 40% and higher is complicated by both physiological responses, particularly water exchange through transpiration, and inhibitory effects of D2O on germination, rooting, and growth. The highest incorporation of 40-50% had been reported for photoheterotrophic cultivation of the duckweed Lemna. Higher substitution is desirable for certain applications using neutron scattering and nuclear magnetic resonance (NMR) techniques. (1)H(2)H NMR and mass spectroscopy are standard methods frequently used for determination of location and amount of deuterium substitution. The changes in infrared (IR) absorption observed for H to D substitution in hydroxyl and alkyl groups provide rapid initial evaluation of incorporation. Short-term experiments with cold-tolerant annual grasses can be carried out in enclosed growth containers to evaluate incorporation. Growth in individual chambers under continuous air perfusion with dried sterile-filtered air enables long-term cultivation of multiple plants at different D2O concentrations. Vegetative propagation from cuttings extends capabilities to species with low germination rates. Cultivation in 50% D2O of annual ryegrass and switchgrass following establishment of roots by growth in H2O produces samples with normal morphology and 30-40% deuterium incorporation in the biomass. Winter grain rye (Secale cereale) was found to efficiently incorporate deuterium by photosynthetic fixation from 50% D2O but did not incorporate deuterated phenylalanine-d8 from the growth medium.
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Affiliation(s)
- Barbara R Evans
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA.
| | - Riddhi Shah
- Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville, Tennessee, USA; Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
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Lam L, Soong R, Sutrisno A, de Visser R, Simpson MJ, Wheeler HL, Campbell M, Maas WE, Fey M, Gorissen A, Hutchins H, Andrew B, Struppe J, Krishnamurthy S, Kumar R, Monette M, Stronks HJ, Hume A, Simpson AJ. Comprehensive multiphase NMR spectroscopy of intact ¹³C-labeled seeds. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2014; 62:107-115. [PMID: 24354469 DOI: 10.1021/jf4045638] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Seeds are complex entities composed of liquids, gels, and solids. NMR spectroscopy is a powerful tool for studying molecular structure but has evolved into two fields, solution and solid state. Comprehensive multiphase (CMP) NMR spectroscopy is capable of liquid-, gel-, and solid-state experiments for studying intact samples where all organic components are studied and differentiated in situ. Herein, intact (13)C-labeled seeds were studied by a variety of 1D/2D (1)H/(13)C experiments. In the mobile phase, an assortment of metabolites in a single (13)C-labeled wheat seed were identified; the gel phase was dominated by triacylglycerides; the semisolid phase was composed largely of carbohydrate biopolymers, and the solid phase was greatly influenced by starchy endosperm signals. Subsequently, the seeds were compared and relative similarities and differences between seed types discussed. This study represents the first application of CMP-NMR to food chemistry and demonstrates its general utility and feasibility for studying intact heterogeneous samples.
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Affiliation(s)
- Leayen Lam
- Department of Physical and Environment Sciences, University of Toronto Scarborough , 1265 Military Trail, Toronto, Ontario, Canada M1C 1A4
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