scholarly journals Genetic Modification of KNAT7 Transcription Factor Expression Enhances Saccharification and Reduces Recalcitrance of Woody Biomass in Poplars

2021 ◽  
Vol 12 ◽  
Author(s):  
Yogesh Kumar Ahlawat ◽  
Akula Nookaraju ◽  
Anne E. Harman-Ware ◽  
Crissa Doeppke ◽  
Ajaya K. Biswal ◽  
...  
Keyword(s):  
Lignin Content ◽  
Woody Biomass ◽  
Bioenergy Crops ◽  
Transgenic Lines ◽  
Saccharification Efficiency ◽  
Transgenic Poplars ◽  
Specific Alteration ◽  
Guaiacyl Lignin ◽  
Transcription Factor Expression ◽  
The Impact

The precise role of KNAT7 transcription factors (TFs) in regulating secondary cell wall (SCW) biosynthesis in poplars has remained unknown, while our understanding of KNAT7 functions in other plants is continuously evolving. To study the impact of genetic modifications of homologous and heterologous KNAT7 gene expression on SCW formation in transgenic poplars, we prepared poplar KNAT7 (PtKNAT7) overexpression (PtKNAT7-OE) and antisense suppression (PtKNAT7-AS) vector constructs for the generation of transgenic poplar lines via Agrobacterium-mediated transformation. Since the overexpression of homologous genes can sometimes result in co-suppression, we also overexpressed Arabidopsis KNAT7 (AtKNAT7-OE) in transgenic poplars. In all these constructs, the expression of KNAT7 transgenes was driven by developing xylem (DX)-specific promoter, DX15. Compared to wild-type (WT) controls, many SCW biosynthesis genes downstream of KNAT7 were highly expressed in poplar PtKNAT7-OE and AtKNAT7-OE lines. Yet, no significant increase in lignin content of woody biomass of these transgenic lines was observed. PtKNAT7-AS lines, however, showed reduced expression of many SCW biosynthesis genes downstream of KNAT7 accompanied by a reduction in lignin content of wood compared to WT controls. Syringyl to Guaiacyl lignin (S/G) ratios were significantly increased in all three KNAT7 knockdown and overexpression transgenic lines than WT controls. These transgenic lines were essentially indistinguishable from WT controls in terms of their growth phenotype. Saccharification efficiency of woody biomass was significantly increased in all transgenic lines than WT controls. Overall, our results demonstrated that developing xylem-specific alteration of KNAT7 expression affects the expression of SCW biosynthesis genes, impacting at least the lignification process and improving saccharification efficiency, hence providing one of the powerful tools for improving bioethanol production from woody biomass of bioenergy crops and trees.

scholarly journals Overexpression of the rice BAHD acyltransferase AT10 increases xylan-bound p-coumarate and reduces lignin in Sorghum bicolor

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Yang Tian ◽  
Chien-Yuan Lin ◽  
Joon-Hyun Park ◽  
Chuan-Yin Wu ◽  
Ramu Kakumanu ◽  
...  
Keyword(s):  
Cell Wall ◽  
Sorghum Bicolor ◽  
Cell Walls ◽  
Lignin Content ◽  
Complex Structure ◽  
Enzymatic Saccharification ◽  
Cellulose Microfibrils ◽  
Biomass Composition ◽  
Bioenergy Crops ◽  
Transgenic Lines

Abstract Background The development of bioenergy crops with reduced recalcitrance to enzymatic degradation represents an important challenge to enable the sustainable production of advanced biofuels and bioproducts. Biomass recalcitrance is partly attributed to the complex structure of plant cell walls inside which cellulose microfibrils are protected by a network of hemicellulosic xylan chains that crosslink with each other or with lignin via ferulate (FA) bridges. Overexpression of the rice acyltransferase OsAT10 is an effective bioengineering strategy to lower the amount of FA involved in the formation of cell wall crosslinks and thereby reduce cell wall recalcitrance. The annual crop sorghum represents an attractive feedstock for bioenergy purposes considering its high biomass yields and low input requirements. Although we previously validated the OsAT10 engineering approach in the perennial bioenergy crop switchgrass, the effect of OsAT10 expression on biomass composition and digestibility in sorghum remains to be explored. Results We obtained eight independent sorghum (Sorghum bicolor (L.) Moench) transgenic lines with a single copy of a construct designed for OsAT10 expression. Consistent with the proposed role of OsAT10 in acylating arabinosyl residues on xylan with p-coumarate (pCA), a higher amount of p-coumaroyl-arabinose was released from the cell walls of these lines upon hydrolysis with trifluoroacetic acid. However, no major changes were observed regarding the total amount of pCA or FA esters released from cell walls upon mild alkaline hydrolysis. Certain diferulate (diFA) isomers identified in alkaline hydrolysates were increased in some transgenic lines. The amount of the main cell wall monosaccharides glucose, xylose, and arabinose was unaffected. The transgenic lines showed reduced lignin content and their biomass released higher yields of sugars after ionic liquid pretreatment followed by enzymatic saccharification. Conclusions Expression of OsAT10 in sorghum leads to an increase of xylan-bound pCA without reducing the overall content of cell wall FA esters. Nevertheless, the amount of total cell wall pCA remains unchanged indicating that most pCA is ester-linked to lignin. Unlike other engineered plants overexpressing OsAT10 or a phylogenetically related acyltransferase with similar putative function, the improvements of biomass saccharification efficiency in sorghum OsAT10 lines are likely the result of lignin reductions rather than reductions of cell wall-bound FA. These results also suggest a relationship between xylan-bound pCA and lignification in cell walls.

scholarly journals Expression of a bacterial 3-dehydroshikimate dehydratase (QsuB) reduces lignin and improves biomass saccharification efficiency in switchgrass (Panicum virgatum L.)

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Zhangying Hao ◽  
Sasha Yogiswara ◽  
Tong Wei ◽  
Veronica Teixeira Benites ◽  
Anagh Sinha ◽  
...  
Keyword(s):  
Panicum Virgatum ◽  
Lignin Content ◽  
Biomass Conversion ◽  
Value Added ◽  
Bioenergy Crops ◽  
Altered Expression ◽  
Fusion Construct ◽  
Model Plant ◽  
Biomass Saccharification ◽  
Saccharification Efficiency

Abstract Background Lignin deposited in plant cell walls negatively affects biomass conversion into advanced bioproducts. There is therefore a strong interest in developing bioenergy crops with reduced lignin content or altered lignin structures. Another desired trait for bioenergy crops is the ability to accumulate novel bioproducts, which would enhance the development of economically sustainable biorefineries. As previously demonstrated in the model plant Arabidopsis, expression of a 3-dehydroshikimate dehydratase in plants offers the potential for decreasing lignin content and overproducing a value-added metabolic coproduct (i.e., protocatechuate) suitable for biological upgrading. Results The 3-dehydroshikimate dehydratase QsuB from Corynebacterium glutamicum was expressed in the bioenergy crop switchgrass (Panicum virgatum L.) using the stem-specific promoter of an O-methyltransferase gene (pShOMT) from sugarcane. The activity of pShOMT was validated in switchgrass after observation in-situ of beta-glucuronidase (GUS) activity in stem nodes of plants carrying a pShOMT::GUS fusion construct. Under controlled growth conditions, engineered switchgrass lines containing a pShOMT::QsuB construct showed reductions of lignin content, improvements of biomass saccharification efficiency, and accumulated higher amount of protocatechuate compared to control plants. Attempts to generate transgenic switchgrass lines carrying the QsuB gene under the control of the constitutive promoter pZmUbi-1 were unsuccessful, suggesting possible toxicity issues associated with ectopic QsuB expression during the plant regeneration process. Conclusion This study validates the transfer of the QsuB engineering approach from a model plant to switchgrass. We have demonstrated altered expression of two important traits: lignin content and accumulation of a co-product. We found that the choice of promoter to drive QsuB expression should be carefully considered when deploying this strategy to other bioenergy crops. Field-testing of engineered QsuB switchgrass are in progress to assess the performance of the introduced traits and agronomic performances of the transgenic plants.

scholarly journals Evaluating polymer interplay after hot water pretreatment to investigate maize stem internode recalcitrance

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Amandine Leroy ◽  
Xavier Falourd ◽  
Loïc Foucat ◽  
Valérie Méchin ◽  
Fabienne Guillon ◽  
...  
Keyword(s):  
Cell Wall ◽  
Negative Impact ◽  
Lignin Content ◽  
Structural Features ◽  
Hot Water ◽  
Condensed State ◽  
Structural Factors ◽  
Water Pretreatment ◽  
Hot Water Pretreatment ◽  
The Impact

Abstract Background Biomass recalcitrance is governed by various molecular and structural factors but the interplay between these multiscale factors remains unclear. In this study, hot water pretreatment (HWP) was applied to maize stem internodes to highlight the impact of the ultrastructure of the polymers and their interactions on the accessibility and recalcitrance of the lignocellulosic biomass. The impact of HWP was analysed at different scales, from the polymer ultrastructure or water mobility to the cell wall organisation by combining complementary compositional, spectral and NMR analyses. Results HWP increased the kinetics and yield of saccharification. Chemical characterisation showed that HWP altered cell wall composition with a loss of hemicelluloses (up to 45% in the 40-min HWP) and of ferulic acid cross-linking associated with lignin enrichment. The lignin structure was also altered (up to 35% reduction in β–O–4 bonds), associated with slight depolymerisation/repolymerisation depending on the length of treatment. The increase in $${T}_{1\rho }^{H}$$ T 1 ρ H , $${T}_{HH}$$ T HH and specific surface area (SSA) showed that the cellulose environment was looser after pretreatment. These changes were linked to the increased accessibility of more constrained water to the cellulose in the 5–15 nm pore size range. Conclusion The loss of hemicelluloses and changes in polymer structural features caused by HWP led to reorganisation of the lignocellulose matrix. These modifications increased the SSA and redistributed the water thereby increasing the accessibility of cellulases and enhancing hydrolysis. Interestingly, lignin content did not have a negative impact on enzymatic hydrolysis but a higher lignin condensed state appeared to promote saccharification. The environment and organisation of lignin is thus more important than its concentration in explaining cellulose accessibility. Elucidating the interactions between polymers is the key to understanding LB recalcitrance and to identifying the best severity conditions to optimise HWP in sustainable biorefineries.

scholarly journals Impacts of Long- and Short-Term of Irrigation with Treated Wastewater and Synthetic Fertilizers on the Growth, Biomass, Heavy Metal Content, and Energy Traits of Three Potential Bioenergy Crops in Arid Regions

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3037
Author(s):  
Mahmoud F. Seleiman ◽  
Nasser Al-Suhaibani ◽  
Salah El-Hendawy ◽  
Kamel Abdella ◽  
Majed Alotaibi ◽  
...  
Keyword(s):  
Trace Elements ◽  
Arid Regions ◽  
Biomass Energy ◽  
Recommended Dose ◽  
Treated Wastewater ◽  
Bioenergy Crops ◽  
Virgin Soil ◽  
Field Crops ◽  
Synthetic Fertilizers ◽  
The Impact

The availability of suitable water is an important factor for increasing the cultivated areas and sustainability in arid (i.e., less than 200 mm precipitation per year) and semiarid regions (i.e., 200–700 mm precipitation per year). Therefore, this study aimed to analyze the impact of treated wastewater (TWW) and groundwater (GW) as well as synthetic fertilizers (50% and 100% of the recommended NPK dose; 150–150–60 kg N–P2O5–K2O ha−1) on the growth, biomass, energy traits, and macro and trace elements of maize (Zea mays L.), sorghum (Sorghum bicolor L.), and pearl millet (Pennisetum glaucum L) grown in old cultivated (first location; L1) and virgin soil (L2 and L3) as potential bioenergy crops. The soil in L1 has been irrigated with treated wastewater for the last 15 years and continued to be irrigated with treated wastewater in this investigation. The virgin soil was divided into two parts: the first part was irrigated with TWW, and the second part was irrigated with GW. The experiments were laid out in a split-plot with a randomized complete block design with water treatments (TWW in old and virgin soil, and GW in virgin soil) in main plots, and the two treatments of fertilization (50% and 100% of the recommended NPK dose) were distributed randomly in subplots. Compared with the crops irrigated with GW, the crops irrigated with TWW, whether grown on old or virgin soil, showed higher plant height, total chlorophyll content, leaf area per plant, total biomass, energy content, and gross energy with low ash. They also contained higher (but lower than permissible limits) concentrations of macro-elements (NPK) and trace elements (Fe, Mn, Cu, Zn, Cd, Pb, Ni, and Co). In addition, the application of a 50% recommended dose of NPK with TWW showed equivalent results to a 100% recommended dose of NPK on all measured parameters with few exceptions. In conclusion, the TWW can be used to irrigate field crops allocated for bioenergy production in arid regions because it does not harm the plants and environment. In addition, the 50% recommended dose of NPK fertilizer exerted no negative effects on the growth and energy production of field crops, thereby protecting the environment and reducing the leaching of excessive fertilizers into GW.

scholarly journals Atmospheric fluidized bed gasification of promising biomass fuels in southern European regions

2007 ◽  
Vol 11 (1) ◽  
pp. 5-15 ◽  
Author(s):  
Kyriakos Panopoulos ◽  
Lydia Fryda ◽  
Emmanuel Kakaras
Keyword(s):  
Fluidized Bed ◽  
Lignin Content ◽  
Giant Reed ◽  
Co2 Production ◽  
European Regions ◽  
Biomass Fuels ◽  
Product Gas ◽  
Sorghum Bagasse ◽  
Bed Material ◽  
The Impact

Three promising biomass fuels from southern European regions were gasified atmospherically with air in a lab-scale fluidized bed reactor with quartz or olivine as bed material. The fuels used were an agro-industrial residue (olive bagasse) and the energy crops giant reed and sweet sorghum bagasse. Varying air ratios and temperatures were tested to study the impact on the product gas composition and tar load. Tars were higher in the case of olive bagasse, attributed to its higher lignin content compared to the other two biomasses with higher cellulose. Giant reed gasification causes agglomeration and defluidisation problems at 790?C while olive bagasse shows the least agglomeration tendency. The particular olivine material promoted the destruction of tars, but to a lesser level than other reported works; this was attributed to its limited iron content. It also promoted the H2 and CO2 production while CO content decreased. Methane yield was slightly affected (decreased) with olivine, higher temperatures, and air ratios. Air ratio increase decreased the tar load but at the same time the gas quality deteriorated. .

scholarly journals The comparison of single and double cut harvests on biomass yield, quality and biogas production of Miscanthus × giganteus

2019 ◽  
Vol 65 (No. 7) ◽  
pp. 369-376
Author(s):  
Marta Kupryś-Caruk ◽  
Sławomir Podlaski
Keyword(s):  
Dry Matter ◽  
Anaerobic Fermentation ◽  
Biogas Production ◽  
Lignin Content ◽  
Soluble Sugars ◽  
Water Soluble ◽  
Miscanthus Giganteus ◽  
Yield Quality ◽  
The Impact

The aim of the research was to determine the impact of double-cut harvest system on yield, as well as on suitability of Miscanthus × giganteus biomass for ensiling and biogas production. Biomass was harvested at the end of June (harvest I) and at the beginning of October (harvest II, regrowth). A single-cut regime at the end of October was also conducted. Biomass from harvests I and II was ensiled and subjected to anaerobic fermentation. The total dry matter (DM) yield from double-cut harvest system was similar to the DM yield from one-cut harvest, but two harvests per year had a positive effect on chemical composition of the biomass. C/N ratio and lignin content in the biomass from harvest I was lower compared to the single-cut biomass. Double harvest biomass was susceptible to ensiling, however, the biomass from harvest I characterized by low dry matter and water soluble sugars content resulted in poorer quality of the obtained silage (butyric acid was present). There were no significant differences between the methane yields obtained from ensiled biomass from harvests I and II.

The impact of carbonate salts on char formation and gas evolution during the slow pyrolysis of biomass, cellulose, and lignin

2020 ◽  
Vol 4 (12) ◽  
pp. 5987-6003 ◽  
Author(s):  
Tahereh Jalalabadi ◽  
Matthew Drewery ◽  
Priscilla Tremain ◽  
John Wilkinson ◽  
Behdad Moghtaderi ◽  
...  
Keyword(s):  
Woody Biomass ◽  
Gas Evolution ◽  
Slow Pyrolysis ◽  
Char Formation ◽  
Pyrolysis Of Biomass ◽  
Carbonate Salts ◽  
The Impact

This study deals with the modification of chars derived from different biomass samples (woody biomass, cellulose and lignin).

Altering potato isoprenoid metabolism increases biomass and induces early flowering

2020 ◽  
Vol 71 (14) ◽  
pp. 4109-4124
Author(s):  
Moehninsi ◽  
Iris Lange ◽  
B Markus Lange ◽  
Duroy A Navarre
Keyword(s):  
Metabolic Regulation ◽  
Transcriptional Control ◽  
Mevalonate Pathway ◽  
Early Flowering ◽  
Bioenergy Crops ◽  
Isoprenoid Metabolism ◽  
Transgenic Lines ◽  
Coa Reductase ◽  
Rate Limiting

Abstract Isoprenoids constitute the largest class of plant natural products and have diverse biological functions including in plant growth and development. In potato (Solanum tuberosum), the regulatory mechanism underlying the biosynthesis of isoprenoids through the mevalonate pathway is unclear. We assessed the role of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) homologs in potato development and in the metabolic regulation of isoprenoid biosynthesis by generating transgenic lines with down-regulated expression (RNAi-hmgr) or overexpression (OE) of one (StHMGR1 or StHMGR3) or two genes, HMGR and farnesyl diphosphate synthase (FPS; StHMGR1/StFPS1 or StHMGR3/StFPS1). Levels of sterols, steroidal glycoalkaloids (SGAs), and plastidial isoprenoids were elevated in the OE-HMGR1, OE-HMGR1/FPS1, and OE-HMGR3/FPS1 lines, and these plants exhibited early flowering, increased stem height, increased biomass, and increased total tuber weight. However, OE-HMGR3 lines showed dwarfism and had the highest sterol amounts, but without an increase in SGA levels, supporting a rate-limiting role for HMGR3 in the accumulation of sterols. Potato RNAi-hmgr lines showed inhibited growth and reduced cytosolic isoprenoid levels. We also determined the relative importance of transcriptional control at regulatory points of isoprenoid precursor biosynthesis by assessing gene–metabolite correlations. These findings provide novel insights into specific end-products of the sterol pathway and could be important for crop yield and bioenergy crops.

scholarly journals Characterization and Morphology of Natural Dung Polymer for Potential Industrial Application as Bio-Based Fillers

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3030
Author(s):  
Vinayak Fasake ◽  
Kavya Dashora
Keyword(s):  
Forest Cover ◽  
Lignin Content ◽  
Paper Industry ◽  
Surface Characteristics ◽  
Pulp And Paper ◽  
Information Communication ◽  
Animal Dung ◽  
Alternate Source ◽  
The Impact ◽  
Capital Intensive

The modern-day paper industry is highly capital-intensive industries in the core sector. Though there are several uses of paper for currency, packaging, education, information, communication, trade and hygiene, the flip side of this industry is the impact on the forest resources and other ecosystems which leads to increasing pollution in water and air, influencing several local communities. In the present paper, the authors have tried to explore potential and alternate source of industrial pulp through ruminant animal dung, which is widely available as a rural resource in India. Three types of undigested animal dung fibers from Indigenous cow (IDF), Jersey cow (JDF), and Buffalo (BDF) were taken. Wheat straw (WS) was the main diet of all animals. The cellulose, hemicellulose and lignin content for all animal dung samples were found in a range of (29–31.50%), (21–23.50%), and (11–13%), respectively. The abundant holocellulose and low lignin contents are suitable for handmade pulp and paper. Surface characteristics of fodder (WS) and all dung fibers have been investigated using Fourier Transform Infrared Spectroscopy (FTIR), scanning electron microscopy (SEM), and SEM-Energy dispersive X-ray spectroscopy (SEM-EDX). To increase paper production without damaging forest cover, it is essential to explore unconventional natural resources, such as dung fiber, which have the huge potential to produce pulp and paper, reinforcement components, etc.

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