Barbara R Evans1, Marcus Foston2,3, Hugh M O'Neill4, David Reeves5,6, Caroline Rempe7,8, Kathi McGrath7,9, Arthur J Ragauskas2,5,10, Brian H Davison5. 1. Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA. evansb@ornl.gov. 2. Institute of Paper Science and Technology, School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332, USA. 3. Department of Energy, Environmental and Chemical Engineering, Washington University, St. Louis, MO, 63130, USA. 4. Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA. 5. Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA. 6. Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville, TN, 37996, USA. 7. Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA. 8. School of Genome Science and Technology, F337 Walters Life Science, University of Tennessee, Knoxville, 37996, TN, USA. 9. Sierra Vista High School, Las Vegas, NV, USA. 10. Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN, 37996, USA.
Abstract
MAIN CONCLUSION: 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.
MAIN CONCLUSION: 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.
Entities:
Keywords:
Biomass; Cellulose; Deuteration; Duckweed; Lemna minor; Nuclear magnetic resonance
Authors: Barbara R Evans; Garima Bali; Marcus Foston; Arthur J Ragauskas; Hugh M O'Neill; Riddhi Shah; Joseph McGaughey; David Reeves; Caroline S Rempe; Brian H Davison Journal: Planta Date: 2015-04-21 Impact factor: 4.116