GENETIC MODIFICATION OF LIGNOCELLULOSIC BIOMASS FOR INCREASING SACCHARIFICATION EFFICIENCY IN POPLARS

Relationship between sugarcane culm and leaf biomass composition and saccharification efficiency

Biotechnology for Biofuels ◽

10.1186/s13068-019-1588-3 ◽

2019 ◽

Vol 12 (1) ◽

Cited By ~ 3

Author(s):

K. Hodgson-Kratky ◽

G. Papa ◽

A. Rodriguez ◽

V. Stavila ◽

B. Simmons ◽

...

Keyword(s):

Cell Wall ◽

Ionic Liquid ◽

Lignocellulosic Biomass ◽

Plant Cell Wall ◽

Biomass Composition ◽

Leaf Biomass ◽

Dilute Acid ◽

Sugarcane Varieties ◽

Saccharification Efficiency ◽

G Ratio

Abstract Background Lignocellulosic biomass is recognized as a promising renewable feedstock for the production of biofuels. However, current methods for converting biomass into fermentable sugars are considered too expensive and inefficient due to the recalcitrance of the secondary cell wall. Biomass composition can be modified to create varieties that are efficiently broken down to release cell wall sugars. This study focused on identifying the key biomass components influencing plant cell wall recalcitrance that can be targeted for selection in sugarcane, an important and abundant source of biomass. Results Biomass composition and the amount of glucan converted into glucose after saccharification were measured in leaf and culm tissues from seven sugarcane genotypes varying in fiber composition after no pretreatment and dilute acid, hydrothermal and ionic liquid pretreatments. In extractives-free sugarcane leaf and culm tissue, glucan, xylan, acid-insoluble lignin (AIL) and acid-soluble lignin (ASL) ranged from 20 to 32%, 15% to 21%, 14% to 20% and 2% to 4%, respectively. The ratio of syringyl (S) to guaiacyl (G) content in the lignin ranged from 1.5 to 2.2 in the culm and from 0.65 to 1.1 in the leaf. Hydrothermal and dilute acid pretreatments predominantly reduced xylan content, while the ionic liquid (IL) pretreatment targeted AIL reduction. The amount of glucan converted into glucose after 26 h of pre-saccharification was highest after IL pretreatment (42% in culm and 63.5% in leaf) compared to the other pretreatments. Additionally, glucan conversion in leaf tissues was approximately 1.5-fold of that in culm tissues. Percent glucan conversion varied between genotypes but there was no genotype that was superior to all others across the pretreatment groups. Path analysis revealed that S/G ratio, AIL and xylan had the strongest negative associations with percent glucan conversion, while ASL and glucan content had strong positive influences. Conclusion To improve saccharification efficiency of lignocellulosic biomass, breeders should focus on reducing S/G ratio, xylan and AIL content and increasing ASL and glucan content. This will be key for the development of sugarcane varieties for bioenergy uses.

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Advantageous conditions of saccharification of lignocellulosic biomass for biofuels generation via fermentation processes

Chemical Papers ◽

10.1007/s11696-019-00960-1 ◽

2019 ◽

Vol 74 (4) ◽

pp. 1199-1209 ◽

Cited By ~ 6

Author(s):

Karolina Kucharska ◽

Edyta Słupek ◽

Hubert Cieśliński ◽

Marian Kamiński

Keyword(s):

Lignocellulosic Biomass ◽

Hydrogen Generation ◽

Operating Conditions ◽

Unit Operations ◽

Biomass Structure ◽

Saccharification Efficiency ◽

Pre Treatment ◽

Complex Polymers ◽

Simple Molecules ◽

Main Component

Abstract Processing of lignocellulosic biomass includes four major unit operations: pre-treatment, hydrolysis, fermentation and product purification prior to biofuel generation via anaerobic digestion. The microorganisms involved in the fermentation metabolize only simple molecules, i.e., monosugars which can be obtained by carrying out the degradation of complex polymers, the main component of lignocellulosic biomass. The object of this paper was to evaluate the saccharification conditions and identify the process parameters that should be applied to improve the saccharification efficiency of lignocellulosic biomass, defined as the simple sugars concentration, which was considered as a crucial parameter for hydrogen generation via dark fermentation. Drawing global conclusions about the occurring changes in the biomass requires learning about the nature of the biomass structure and composition at different stages of the process. Therefore, techniques for analysis, as FTIR, HPLC and SEM were applied. The experiment was planned employing Box–Behnken design. The advantageous operating conditions and the composition of saccharification enzymatic cocktail were identified and their values occurred similar in the applied border conditions for all tested biomass types. Analysis of the intermediate solid and liquid streams generated during the pre-treatment procedure revealed several structural and compositional changes in the biomass.

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Low-Cost Cellulase-Hemicellulase Mixture Secreted by Trichoderma harzianum EM0925 with Complete Saccharification Efficacy of Lignocellulose

International Journal of Molecular Sciences ◽

10.3390/ijms21020371 ◽

2020 ◽

Vol 21 (2) ◽

pp. 371 ◽

Cited By ~ 7

Author(s):

Yu Zhang ◽

Jinshui Yang ◽

Lijin Luo ◽

Entao Wang ◽

Ruonan Wang ◽

...

Keyword(s):

Lignocellulosic Biomass ◽

Trichoderma Harzianum ◽

Low Cost ◽

Value Added ◽

Industrial Applications ◽

Fermentable Sugars ◽

Enzyme Preparations ◽

Ultrafine Grinding ◽

Saccharification Efficiency ◽

Important Intermediate

Fermentable sugars are important intermediate products in the conversion of lignocellulosic biomass to biofuels and other value-added bio-products. The main bottlenecks limiting the production of fermentable sugars from lignocellulosic biomass are the high cost and the low saccharification efficiency of degradation enzymes. Herein, we report the secretome of Trichoderma harzianum EM0925 under induction of lignocellulose. Numerously and quantitatively balanced cellulases and hemicellulases, especially high levels of glycosidases, could be secreted by T. harzianum EM0925. Compared with the commercial enzyme preparations, the T. harzianum EM0925 enzyme cocktail presented significantly higher lignocellulolytic enzyme activities and hydrolysis efficiency against lignocellulosic biomass. Moreover, 100% yields of glucose and xylose were obtained simultaneously from ultrafine grinding and alkali pretreated corn stover. These findings demonstrate a natural cellulases and hemicellulases mixture for complete conversion of biomass polysaccharide, suggesting T. harzianum EM0925 enzymes have great potential for industrial applications.

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Enhanced saccharification efficiency of lignocellulosic biomass of mustard stalk and straw by salt pretreatment

Industrial Crops and Products ◽

10.1016/j.indcrop.2015.10.049 ◽

2016 ◽

Vol 80 ◽

pp. 42-49 ◽

Cited By ~ 18

Author(s):

Debopam Banerjee ◽

Siddhartha Mukherjee ◽

Swagata Pal ◽

Suman Khowala

Keyword(s):

Lignocellulosic Biomass ◽

Saccharification Efficiency

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CRISPR-Knockout of CSE Gene Improves Saccharification Efficiency by Reducing Lignin Content in Hybrid Poplar

International Journal of Molecular Sciences ◽

10.3390/ijms22189750 ◽

2021 ◽

Vol 22 (18) ◽

pp. 9750

Author(s):

Hyun-A Jang ◽

Eun-Kyung Bae ◽

Min-Ha Kim ◽

Su-Jin Park ◽

Na-Young Choi ◽

...

Keyword(s):

Lignocellulosic Biomass ◽

Lignin Content ◽

Hybrid Poplar ◽

Lignin Biosynthesis ◽

Biofuel Production ◽

Guide Rnas ◽

Hybrid Poplars ◽

Four Seasons ◽

Promising Target ◽

Saccharification Efficiency

Caffeoyl shikimate esterase (CSE) has been shown to play an important role in lignin biosynthesis in plants and is, therefore, a promising target for generating improved lignocellulosic biomass crops for sustainable biofuel production. Populus spp. has two CSE genes (CSE1 and CSE2) and, thus, the hybrid poplar (Populus alba × P. glandulosa) investigated in this study has four CSE genes. Here, we present transgenic hybrid poplars with knockouts of each CSE gene achieved by CRISPR/Cas9. To knockout the CSE genes of the hybrid poplar, we designed three single guide RNAs (sg1–sg3), and produced three different transgenic poplars with either CSE1 (CSE1-sg2), CSE2 (CSE2-sg3), or both genes (CSE1/2-sg1) mutated. CSE1-sg2 and CSE2-sg3 poplars showed up to 29.1% reduction in lignin deposition with irregularly shaped xylem vessels. However, CSE1-sg2 and CSE2-sg3 poplars were morphologically indistinguishable from WT and showed no significant differences in growth in a long-term living modified organism (LMO) field-test covering four seasons. Gene expression analysis revealed that many lignin biosynthetic genes were downregulated in CSE1-sg2 and CSE2-sg3 poplars. Indeed, the CSE1-sg2 and CSE2-sg3 poplars had up to 25% higher saccharification efficiency than the WT control. Our results demonstrate that precise editing of CSE by CRISPR/Cas9 technology can improve lignocellulosic biomass without a growth penalty.

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