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Winter rye as a bioenergy feedstock: impact of crop maturity on composition, biological solubilization and potential revenue

BACKGROUND: Winter annual crops such as winter rye (Secale cereale L) can produce biomass feedstock on seasonally fallow land that continues to provide high-value food and feed from summer annuals such as corn and soybeans. As energy double crops, winter grasses are likely to be harvested while stil...

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Autores principales: Shao, Xiongjun, DiMarco, Kay, Richard, Tom L, Lynd, Lee R
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2015
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4367844/
https://www.ncbi.nlm.nih.gov/pubmed/25798193
http://dx.doi.org/10.1186/s13068-015-0225-z
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author Shao, Xiongjun
DiMarco, Kay
Richard, Tom L
Lynd, Lee R
author_facet Shao, Xiongjun
DiMarco, Kay
Richard, Tom L
Lynd, Lee R
author_sort Shao, Xiongjun
collection PubMed
description BACKGROUND: Winter annual crops such as winter rye (Secale cereale L) can produce biomass feedstock on seasonally fallow land that continues to provide high-value food and feed from summer annuals such as corn and soybeans. As energy double crops, winter grasses are likely to be harvested while still immature and thus structurally different from the fully senesced plant material typically used for biofuels. This study investigates the dynamic trends in biomass yield, composition, and biological solubilization over the course of a spring harvest season. RESULTS: The water soluble fraction decreased with increasing maturity while total carbohydrate content stayed roughly constant at about 65%. The protein mass fraction decreased with increasing maturity, but was counterbalanced by increasing harvest yield resulting in similar total protein across harvest dates. Winter rye was ground and autoclaved then fermented at 15 g/L total solids by either (1) Clostridium thermocellum or (2) simultaneous saccharification and cofermentation (SSCF) using commercial cellulases (CTec2 and HTec2) and a xylose-fermenting Saccharomyces cerevisiae strain. Solubilization of total carbohydrate dropped significantly as winter rye matured for both C. thermocellum (from approximately 80% to approximately 50%) and SSCF (from approximately 60% to approximately 30%). C. thermocellum achieved total solubilization 33% higher than that of SSCF for the earliest harvest date and 50% higher for the latest harvest date. Potential revenue from protein and bioethanol was stable over a range of different harvest dates, with most of the revenue due to ethanol. In a crop rotation with soybean, recovery of the soluble protein from winter rye could increase per hectare protein production by 20 to 35%. CONCLUSIONS: Double-cropping winter rye can produce significant biomass for biofuel production and feed protein as coproduct without competing with the main summer crop. During a 24-day harvest window, the total carbohydrate content remained relatively constant while the early-harvest yielded much higher carbohydrate solubilization for both C. thermocellum fermentation and SSCF. C. thermocellum fermentation achieved higher carbohydrate solubilization than SSCF across all growth stages tested. Although winter rye’s yield, composition, and biological reactivity change rapidly in the spring, it offers a substantial and stable income across the harvest season and thus flexibility for the farmer. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13068-015-0225-z) contains supplementary material, which is available to authorized users.
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spelling pubmed-43678442015-03-21 Winter rye as a bioenergy feedstock: impact of crop maturity on composition, biological solubilization and potential revenue Shao, Xiongjun DiMarco, Kay Richard, Tom L Lynd, Lee R Biotechnol Biofuels Research Article BACKGROUND: Winter annual crops such as winter rye (Secale cereale L) can produce biomass feedstock on seasonally fallow land that continues to provide high-value food and feed from summer annuals such as corn and soybeans. As energy double crops, winter grasses are likely to be harvested while still immature and thus structurally different from the fully senesced plant material typically used for biofuels. This study investigates the dynamic trends in biomass yield, composition, and biological solubilization over the course of a spring harvest season. RESULTS: The water soluble fraction decreased with increasing maturity while total carbohydrate content stayed roughly constant at about 65%. The protein mass fraction decreased with increasing maturity, but was counterbalanced by increasing harvest yield resulting in similar total protein across harvest dates. Winter rye was ground and autoclaved then fermented at 15 g/L total solids by either (1) Clostridium thermocellum or (2) simultaneous saccharification and cofermentation (SSCF) using commercial cellulases (CTec2 and HTec2) and a xylose-fermenting Saccharomyces cerevisiae strain. Solubilization of total carbohydrate dropped significantly as winter rye matured for both C. thermocellum (from approximately 80% to approximately 50%) and SSCF (from approximately 60% to approximately 30%). C. thermocellum achieved total solubilization 33% higher than that of SSCF for the earliest harvest date and 50% higher for the latest harvest date. Potential revenue from protein and bioethanol was stable over a range of different harvest dates, with most of the revenue due to ethanol. In a crop rotation with soybean, recovery of the soluble protein from winter rye could increase per hectare protein production by 20 to 35%. CONCLUSIONS: Double-cropping winter rye can produce significant biomass for biofuel production and feed protein as coproduct without competing with the main summer crop. During a 24-day harvest window, the total carbohydrate content remained relatively constant while the early-harvest yielded much higher carbohydrate solubilization for both C. thermocellum fermentation and SSCF. C. thermocellum fermentation achieved higher carbohydrate solubilization than SSCF across all growth stages tested. Although winter rye’s yield, composition, and biological reactivity change rapidly in the spring, it offers a substantial and stable income across the harvest season and thus flexibility for the farmer. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13068-015-0225-z) contains supplementary material, which is available to authorized users. BioMed Central 2015-02-27 /pmc/articles/PMC4367844/ /pubmed/25798193 http://dx.doi.org/10.1186/s13068-015-0225-z Text en © Shao et al.; licensee BioMed Central. 2015 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
spellingShingle Research Article
Shao, Xiongjun
DiMarco, Kay
Richard, Tom L
Lynd, Lee R
Winter rye as a bioenergy feedstock: impact of crop maturity on composition, biological solubilization and potential revenue
title Winter rye as a bioenergy feedstock: impact of crop maturity on composition, biological solubilization and potential revenue
title_full Winter rye as a bioenergy feedstock: impact of crop maturity on composition, biological solubilization and potential revenue
title_fullStr Winter rye as a bioenergy feedstock: impact of crop maturity on composition, biological solubilization and potential revenue
title_full_unstemmed Winter rye as a bioenergy feedstock: impact of crop maturity on composition, biological solubilization and potential revenue
title_short Winter rye as a bioenergy feedstock: impact of crop maturity on composition, biological solubilization and potential revenue
title_sort winter rye as a bioenergy feedstock: impact of crop maturity on composition, biological solubilization and potential revenue
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4367844/
https://www.ncbi.nlm.nih.gov/pubmed/25798193
http://dx.doi.org/10.1186/s13068-015-0225-z
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