Enzymatic digestion of liquid hot water pretreated hybrid poplar

Liquid hot (LHW) water pretreatment (LHW) of lignocellulosic material enhances enzymatic conversion of cellulose to glucose by solubilizing hemicellulose fraction of the biomass, while leaving the cellulose more reactive and accessible to cellulase enzymes. Within the range of pretreatment conditions tested in this study, the optimized LHW pretreatment conditions for a 15% (wt/vol) slurry of hybrid poplar were found to be 200^oC, 10 min, which resulted in the highest fermentable sugar yield with minimal formation of sugar decomposition products during the pretreatment. The LHW pretreatment solubilized 62% of hemicellulose as soluble oligomers. Hot‐washing of the pretreated poplar slurry increased the efficiency of hydrolysis by doubling the yield of glucose for a given enzyme dose. The 15% (wt/vol) slurry of hybrid poplar, pretreated at the optimal conditions and hot‐washed, resulted in 54% glucose yield by 15 FPU cellulase per gram glucan after 120 h. The hydrolysate contained 56 g/L glucose and 12 g/L xylose. The effect of cellulase loading on the enzymatic digestibility of the pretreated poplar is also reported. Total monomeric sugar yield (glucose and xylose) reached 67% after 72 h of hydrolysis when 40 FPU cellulase per gram glucan were used. An overall mass balance of the poplar‐to‐ethanol process was established based on the experimentally determined composition and hydrolysis efficiencies of the liquid hot water pretreated poplar. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009     

Techno-economic potential of bioethanol from bamboo in China

Background

Bamboo is potentially an interesting feedstock for advanced bioethanol production in China due to its natural abundance, rapid growth, perennial nature and low management requirements. Liquid hot water (LHW) pretreatment was selected as a promising technology to enhance sugar release from bamboo lignocellulose whilst keeping economic and environmental costs to a minimum. The present research was conducted to assess: 1) by how much LHW pretreatment can enhance sugar yields in bamboo, and 2) whether this process has the potential to be economically feasible for biofuel use at the commercial scale. Pretreatments were performed at temperatures of 170-190°C for 10–30 minutes, followed by enzymatic saccharification with a commercial enzyme cocktail at various loadings. These data were then used as inputs to a techno-economic model using AspenPlus? to determine the production cost of bioethanol from bamboo in China.

Results

At the selected LHW pretreatment of 190°C for 10 minutes, 69% of the initial sugars were released under a standardised enzyme loading; this varied between 59-76% when 10–140 FPU/g glucan of commercial enzyme Cellic CTec2 was applied. Although the lowest enzyme loading yielded the least amount of bioethanol, the techno-economic evaluation revealed it to be the most economically viable scenario with a production cost of $0.484 per litre (with tax exemption and a $0.16/litre subsidy). The supply-chain analysis demonstrated that bioethanol could be economically competitive with petrol at the pump at enzyme loadings up to 60 FPU/g glucan. However, in a prospective scenario with reduced government support, this enzyme loading threshold would be reduced to 30 FPU/g glucan.

Conclusions

Bioethanol from bamboo is shown to be both technically and economically feasible, as well as competitive with petrol in China. Alternative approaches to reduce bioethanol production costs are still needed however, to ensure its competitiveness in a possible future scenario where neither tax exemptions nor subsidies are granted to producers. These measures may include improving sugar release with more effective pretreatments and reduced enzyme usage, accessing low cost bamboo feedstock or selecting feedstocks with higher/more accessible cellulose.

     

Variation in Cell Wall Composition and Accessibility in Relation to Biofuel Potential of Short Rotation Coppice Willows

Short rotation coppice (SRC) willow is currently emerging as an important dedicated lignocellulosic energy crop in the UK. However, investigation into the variation between species and genotypes in their suitability for liquid transport biofuel processing has been limited. To address this, four traits relevant to biofuel processing (composition, enzymatic saccharification, response to pretreatment and projected ethanol yields) were studied in 35 genotypes of willow including Europe’s leading SRC willow cultivars. Large, genotype-specific variation was observed for all four traits. Significant positive correlations were identified between the accessibility of glucan to enzymatic saccharification before and after pretreatment as well as glucose release and xylose release via acid hydrolysis during pretreatment. Of particular interest is that the lignin content of the biomass did not correlate with accessibility of glucan to enzymatic saccharification. The genotype-specific variations identified have implications for SRC willow breeding and for potential reductions in both the net energy expenditure and environmental impact of the lignocellulosic biofuel process chain. The large range of projected ethanol yields demonstrate the importance of feedstock selection based on an ideotype encompassing the performance of both field biomass growth and ease of conversion.     

Plantain fibre bundles isolated from Colombian agro-industrial residues

Comestible fruit production from Musaceas plants is an important economical activity in developing countries like Colombia. However, it generates a large amount of agro-industrial residues. Some of them are a potential resource of natural fibres, which can be used as reinforcement for composite materials. In this work, a series of commercial plantain (Musa AAB, cv "Dominico Harton") fibre bundles extracted from pseudostem, leaf sheath and rachis agricultural wastes were analyzed. Mechanical decortication and biological retting processes were used during fiber extraction. No significant differences in composition of vascular bundles were observed for both extraction processes. Gross morphological characteristics and mechanical behavior have been evaluated. Conducting tissues with spiral-like arrangement are observed attached to fibre bundles. This fact suggests a big amount of these tissues in commercial plantain plants. Both used extraction methods are not enough to remove them. Pseudostem fibre bundles have higher specific strength and modulus and lower strain at break than leaf sheath and rachis fibre bundles, having values comparable to other lignocellulosic fibres bundles.     

Increased bioethanol production from commercial tobacco cultivars overexpressing thioredoxin f grown under field conditions

Bioethanol is mainly produced from food crops such as sugar cane and maize, and this has been held partly responsible for the rise of food commodity prices. Tobacco, integrated in biorefinery facilities for the extraction of different compounds, could become an alternative feedstock for biofuel production. When grown for energy production, using high plant densities and several mowings during the growing season, tobacco can produce large amounts of inexpensive green biomass. We have bred two commercial tobacco cultivars (Virginia Gold and Havana 503B) to increase the carbohydrate content by the overexpression of thioredoxin f in the chloroplast. Marker-free transplastomic plants were recovered and their agronomic performance under field conditions was evaluated. These plants were phenotypically equivalent to their wild types yet showed increased starch (up to 280 %) and soluble sugar (up to 74 %) contents in leaves relative to their control plants. Fermentable sugars released from the stalk were also higher (up to 24 %) for transplastomic plants. After heat pretreatment, enzymatic hydrolysis and yeast fermentation of leaf and stalk hydrolysates, an average of 20–40 % more ethanol was obtained from transplastomic plants than their wild-type controls. We propose an integral exploitation of the entire tobacco plant managed as a forage crop (harvesting sugar and starch-rich leaves and lignocellulosic stalks) that could considerably cheapen the entire production process.     

Simultaneous saccharification and fermentation of steam-exploded corn stover at high glucan loading and high temperature

Background

Simultaneous saccharification and fermentation (SSF) is a promising process for bioconversion of lignocellulosic biomass. High glucan loading for hydrolysis and fermentation is an efficient approach to reduce the capital costs for bio-based products production. The SSF of steam-exploded corn stover (SECS) for ethanol production at high glucan loading and high temperature was investigated in this study.

Results

Glucan conversion of corn stover biomass pretreated by steam explosion was maintained at approximately 71 to 79% at an enzyme loading of 30 filter paper units (FPU)/g glucan, and 74 to 82% at an enzyme loading of 60 FPU/g glucan, with glucan loading varying from 3 to 12%. Glucan conversion decreased obviously with glucan loading beyond 15%. The results indicated that the mixture was most efficient in enzymatic hydrolysis of SECS at 3 to 12% glucan loading. The optimal SSF conditions of SECS using a novel Saccharomyces cerevisiae were inoculation optical density (OD)₆₀₀?=?4.0, initial pH 4.8, 50% nutrients added, 36 hours pre-hydrolysis time, 39°C, and 12% glucan loading (20% solid loading). With the addition of 2% Tween 20, glucan conversion, ethanol yield, final ethanol concentration reached 78.6%, 77.2%, and 59.8 g/L, respectively, under the optimal conditions. The results suggested that the solid and degradation products’ inhibitory effect on the hydrolysis and fermentation of SECS were also not obvious at high glucan loading. Additionally, glucan conversion and final ethanol concentration in SSF of SECS increased by 13.6% and 18.7%, respectively, compared with separate hydrolysis and fermentation (SHF).

Conclusions

Our research suggested that high glucan loading (6 to 12% glucan loading) and high temperature (39°C) significantly improved the SSF performance of SECS using a thermal- and ethanol-tolerant strain of S. cerevisiae due to the removal of degradation products, sugar feedback, and solid’s inhibitory effects. Furthermore, the surfactant addition obviously increased ethanol yield in SSF process of SECS.

     

Production and partial purification of cellulase from a novel fungus,Aspergillus flavus BS1

This study describes the isolation and characterization of a novel fungus, Aspergillus flavus BS1 and its cellulolytic activities with special emphasis on endoglucanase production. Preliminary screening studies showed that A. flavus BS1 was a potent strain for the production of cellulase. To study the cellulolytic activities in detail by submerged fermentation (SmF), productions of endoglucanase, exoglucanase, and β-glucosidase were estimated from the basal salt medium (BSM) supplemented with 1 % carboxy methyl cellulose (CMC). CMC medium supported the maximum yield of endoglucanase (2,793 U/ml) on day 5 of incubation at 28 °C and 150 rpm, which was higher than that obtained with naturally available supplements (flour) from banana, tapioca, potato, or banana peel. During cellulase production by solid-state fermentation, 10 % (w/w) tapioca flour in sawdust (teak wood) moisturized with BSM (1:2, w/v) supported maximum cellulase yield (5,408 U/g dry substrate) on day 3 at 28 °C, which was 2-fold higher than that obtained during SmF. The active cellulase was qualitatively estimated by polyacrylamide gel electrophoresis (PAGE). Native-PAGE (0.25 % CMC impregnated on the 10 % gel) activity staining with congo-red showed a clear zone for CMCase activity, whereas SDS-PAGE showed a distinct band. In conclusion, this study showed that A. flavus strain BS1 is a potent strain for the production of cellulase on lignocellulosic media, the hot enzyme for bioethanol production from the lignocellulosic biomass by SSF.     

Effect of physicochemical pre-treatment of rice straw on its digestibility by <Emphasis Type="Italic">Clostridium cellulolyticum</Emphasis>

Rice straw (RS) may serve as a low-cost biomass for the production of biofuels and biochemicals, but its native structure is resistant to enzymatic and microbial deconstruction. Therefore, an efficient pre-treatment method is required to modify crystalline cellulose to a more reactive amorphous form. This work investigated pre-treatments of rice straw involving size reduction (S) followed by either sodium hydroxide (NaOH) or diluted sulfuric acid (H₂SO₄) and liquid hot water (LHW). The shrinkage of the vascular bundles in the rice straw structure pre-treated with NaOH–LHW–S was higher than that with LHW–S and H₂SO₄–LHW–S pre-treatments. The highest levels of total fermentative products and residual sugars were obtained at the concentrations of 7.8 ± 0.2 and 2.1 ± 0.3 g/L, respectively, after fermentation by Clostridium cellulolyticum for NaOH–LHW–S pre-treated rice straw at 121 °C for 120 min. Overall, the combined physicochemical pre-treatment of RS led to improved microbial hydrolysis during cellulose degradation at the percentage of 85.5 ± 0.5.     

Agriculture and Inequality in the Colonial Andes: A Simulation of Production and Consumption Using Administrative Documents

During the sixteenth and seventeenth centuries, indigenous communities in the Viceroyalty of Peru suffered forced resettlement, introduced disease, and onerous colonial tribute levies. These produced an onslaught of petitions for new tribute counts, as their diminished populations were obliged to pay the head taxes set by earlier censuses. The resulting visitas (administrative surveys) provide a wealth of information on the demography and agricultural systems of colonial Andean communities. However, comparatively little quantitative research exists on the distribution of agricultural resources and the nutritional demands of households. We model agricultural production and nutritional demand using household demographic and landholding declarations in the visitas from the Colca Valley of southern highland Peru, combined with ethnographically-derived estimates of agricultural production and nutritional demand. The results indicate that despite surplus agricultural production in the aggregate, there were significant differences in intra- and inter-community land wealth and production sufficiency ratios, leaving about 30% of households with caloric shortfalls. In contrast to regional-scale carrying capacity-type models, this simulation characterizes agricultural inequality within colonial Andean communities, and thus accounts for the hardship evidenced by tributary recount petitions, even in a breadbasket province from which much surplus production was extracted to fill colonial coffers.

Optimization of Enzymatic Hydrolysis of Steam Pretreated Triticale Straw

Efficient conversion of the carbohydrates into fermentable sugars is crucial for industrial implementation of 2G biofuels such as bioethanol. The main objective of this study was to improve the enzymatic hydrolysis of steam pretreated triticale straw (slurry, pressed-slurry or water insoluble solids (WIS)) by optimal combination of cellulase (Cellic® CTec2) and hemicellulase (Cellic® HTec2) and incubation period for a target glucan conversion of 80 %. Among the three substrates evaluated, pressed-slurry and WIS resulted in similar sugar yields but WIS presented lower enzyme requirements. Different combinations of cellulase and endo-xylanase could provide an 80 % of glucan conversion depending on the weight assigned to constrain. The selected enzyme combination, 0.1 mL Cellic®CTec2/g WIS and 0.2 mL Cellic®HTec2/g WIS, could achieve a glucan conversion of 80 % in 45 h (desirability of 0.9). Doubling the enzyme dosage could further improve the saccharification productivity by reducing the incubation period to 37 h. The optimisation of enzymatic hydrolysis of lignocellulosic substrates, to reduce the cost of sugars production, is a compromise between substrate, enzyme dosage, incubation time and the benchmark yield, although a more favourable response can be generated with an optimised combination of enzymes.     

Switchgrass in California: where,and at what price?

This article assesses the potential of California agriculture to supply biofuel feedstock in the form of switchgrass. We construct a fully calibrated, multiregion, multi‐input and multioutput model of agricultural supply for California's Central Valley based on the principles of positive mathematical programming. We exploit agronomic information obtained from a biophysical model to estimate regional production functions for switchgrass. The model predicts the extent and location of potential feedstock production in the Central Valley. Our results suggest that switchgrass adoption rates differ widely among agricultural regions, and that switchgrass is not likely to displace specialty crops by much statewide.     

Xylanase and itaconic acid production by Aspergillus terreus NRRL 1960 within a biorefinery concept

Production of two industrially important products, xylanase and itaconic acid (IA), by Aspergillus terreus NRRL 1960 from agricultural residues was investigated within a biorefinery concept. Biological pretreatment was applied to lignocellulosic materials by using A. terreus, which produced xylanase while growing on agricultural residues. For IA production, already grown cells were transferred into a new medium. The first step provided not only the pretreatment of lignocellulosic material in order to be used as feedstock but also production of xylanase. For this purpose, cotton stalk, sunflower stalk and corn cob were used as carbon sources as lignocellulosic material. Among them, the highest xylanase production was obtained on corn cob. By application of two-step fermentation, about 70 IU/mL xylanase and 18 g/L IA production levels were achieved. This study shows the stepwise usage potential of the microorganism as a tool in a biorefinery concept.     

Quantitative proteomic analysis of lignocellulolytic enzymes by Phanerochaete chrysosporium on different lignocellulosic biomass

Lignocellulosic biomass from agricultural crop residues and forest waste represents an abundant renewable resource for bioenergy and future biofuel. The current bottleneck of lignocellulosic biofuel production is the hydrolysis of biomass to sugar. To understand the enzymatic hydrolysis of complex biomasses, in this report, lignocellulolytic enzymes secretion by Phanerochaete chrysosporium cultivated in different natural lignocellulosic biomass such as corn stover, hay, sawdust, sugarcane baggase, wheat bran and wood chips were quantitatively analyzed with the iTRAQ technique using LC-MS/MS. A diverse groups of enzymes, including cellulases, glycoside hydrolases, hemicellulases, lignin degrading enzymes, peroxidases, esterases, lipases, chitinases, peptidases, protein translocating transporter and hypothetical proteins were quantified, of which several were novel lignocellulosic biomass hydrolyzing enzymes. The quantitative expression and regulation of lignocellulolytic enzymes by P. chrysosporium were dependent on the nature and complexity of lignocellulosic biomass as well as physical size of the biomass. The iTRAQ data revealed oxidative and hydrolytic lignin degrading mechanism of P. chrysosporium. Numerous proteins presumed to be involved in natural lignocellulosic biomass transformation and degradation were expressed and produced in variable quantities in response to different agricultural and forest wastes.     

Production of isoprene,one of the high-density fuel precursors,from peanut hull using the high-efficient lignin-removal pretreatment method

Background

Isoprene as the feedstock can be used to produce renewable energy fuels, providing an alternative to replace the rapidly depleting fossil fuels. However, traditional method for isoprene production could not meet the demands for low-energy consumption and environment-friendliness. Moreover, most of the previous studies focused on biofuel production out of lignocellulosic materials such as wood, rice straw, corn cob, while few studies concentrated on biofuel production using peanut hull (PH). As is known, China is the largest peanut producer in the globe with an extremely considerable amount of PH to be produced each year. Therefore, a novel, renewable, and environment-friendly pretreatment strategy to increase the enzymatic hydrolysis efficiency of cellulose and reduce the inhibitors generation was developed to convert PH into isoprene.

Results

The optimal pretreatment conditions were 100 °C, 60 min, 10% (w/v) solid loading with a 2:8 volume ratio of phosphoric acid and of hydrogen peroxide. In comparison with the raw PH, the hemicellulose and lignin were reduced to 85.0 and 98.0%, respectively. The cellulose–glucose conversion of pretreated PH reached up to 95.0% in contrast to that of the raw PH (19.1%). Only three kinds of inhibitors including formic acid, levulinic acid, and a little furfural were formed during the pretreatment process, whose concentrations were too low to inhibit the isoprene yield for Escherichia coli fermentation. Moreover, compared with the isoprene yield of pure glucose fermentation (298 ± 9 mg/L), 249 ± 6.7 and 294 ± 8.3 mg/L of isoprene were produced using the pretreated PH as the carbon source by the engineered strain via separate hydrolysis and fermentation and simultaneous saccharification and fermentation (SSF) methods, respectively. The isoprene production via SSF had a 9.8% glucose–isoprene conversion which was equivalent to 98.8% of isoprene production via the pure glucose fermentation.

Conclusions

The optimized phosphoric acid/hydrogen peroxide combination pretreatment approach was proved effective to remove lignin and hemicellulose from lignocellulosic materials. Meanwhile, the pretreated PH could be converted into isoprene efficiently in the engineered Escherichia coli. It is concluded that this novel strategy of isoprene production using lignocellulosic materials pretreated by phosphoric acid/hydrogen peroxide is a promising alternative to isoprene production using traditional way which can fully utilize non-renewable fossil sources.

     

Effect of certain organic materials in controlling Meloidogyne incognita root-knot nematode infesting banana

Efficacy of certain plant wastes as onion bulb envelope, dry leaves of sugar beet, fleabane and jojoba, filter cake or mud as sugar cane industrial residue and nile fertile mineral bio-fertilisers were studied under field conditions for managing Meloidogyne incognita on banana Cv. Williams. All the tested treatments significantly (P ≤ 0.05 and 0.01) proved to be effective in reducing the studied nematode criteria during the growing season of banana. The highest percentage reductions of 87.5 and 85.5% were recorded in the number of second-stage juveniles caused by fleabane at vegetative and harvest stages, respectively. As for galls, the highest percentage reductions of 80.4 and 79.6% were achieved at harvest stage by sugar beet waste and filter cake residue, respectively. Also, sugar beet waste was the best at increasing banana fruit yield per feddan (77.0%), followed by jojoba (53.1%) and fleabane (50.4%). The number of fingers and hands per bunch increased by the different materials at various degrees.     

Optimization of enzymatic hydrolysis and ethanol fermentation from AFEX-treated rice straw

An abundant agricultural residue, rice straw (RS) was pretreated using ammonia fiber expansion (AFEX) process with less than 3% sugar loss. Along with commercial cellulase (Spezyme® CP) at 15 filter paper unit/g of glucan, the addition of Multifect® Xylanase at 2.67 mg protein/g glucan and Multifect® Pectinase at 3.65 mg protein/g glucan was optimized to greatly increase sugar conversion of AFEX-treated RS. During enzymatic hydrolysis even at 6% glucan loading (equivalent to 17.8% solid loading), about 80.6% of glucan and 89.6% of xylan conversions (including monomeric and oligomeric sugars) were achieved. However, oligomeric glucose and xylose accounted for 12.3% of the total glucose and 37.0% of the total xylose, respectively. Comparison among the three ethanologenic strains revealed Saccharomyces cerevisiae 424A(LNH-ST) to be a promising candidate for RS hydrolysate with maximum ethanol metabolic yield of 95.3% and ethanol volumetric productivity of 0.26 g/L/h. The final concentration of ethanol at 37.0 g/L was obtained by S. cerevisiae 424A(LNH-ST) even with low cell density inoculum. A biorefinery combining AFEX pretreatment with S. cerevisiae 424A(LNH-ST) in separate hydrolysis and fermentation could achieve 175.6 g EtOH/kg untreated rice straw at low initial cell density (0.28 g dw/L) without washing pretreated biomass, detoxification, or nutrient supplementation.     

Lignin monomer composition affects Arabidopsis cell-wall degradability after liquid hot water pretreatment

Background

Lignin is embedded in the plant cell wall matrix, and impedes the enzymatic saccharification of lignocellulosic feedstocks. To investigate whether enzymatic digestibility of cell wall materials can be improved by altering the relative abundance of the two major lignin monomers, guaiacyl (G) and syringyl (S) subunits, we compared the degradability of cell wall material from wild-type Arabidopsis thaliana with a mutant line and a genetically modified line, the lignins of which are enriched in G and S subunits, respectively.

Results

Arabidopsis tissue containing G- and S-rich lignins had the same saccharification performance as the wild type when subjected to enzyme hydrolysis without pretreatment. After a 24-hour incubation period, less than 30% of the total glucan was hydrolyzed. By contrast, when liquid hot water (LHW) pretreatment was included before enzyme hydrolysis, the S-lignin-rich tissue gave a much higher glucose yield than either the wild-type or G-lignin-rich tissue. Applying a hot-water washing step after the pretreatment did not lead to a further increase in final glucose yield, but the initial hydrolytic rate was doubled.

Conclusions

Our analyses using the model plant A. thaliana revealed that lignin composition affects the enzymatic digestibility of LHW pretreated plant material. Pretreatment is more effective in enhancing the saccharification of A. thaliana cell walls that contain S-rich lignin. Increasing lignin S monomer content through genetic engineering may be a promising approach to increase the efficiency and reduce the cost of biomass to biofuel conversion.     

Fermentation of lignocellulosic sugars to acetic acid by <Emphasis Type="Italic">Moorella thermoacetica</Emphasis>

A systematic study of bioconversion of lignocellulosic sugars to acetic acid by Moorella thermoacetica (strain ATCC 39073) was conducted. Four different water-soluble fractions (hydrolysates) obtained after steam pretreatment of lignocellulosic biomass were selected and fermented to acetic acid in batch fermentations. M. thermoacetica can effectively ferment xylose and glucose in hydrolysates from wheat straw, forest residues, switchgrass, and sugarcane straw to acetic acid. Xylose and glucose were completely utilized, with xylose being consumed first. M. thermoacetica consumed up to 62 % of arabinose, 49 % galactose and 66 % of mannose within 72 h of fermentation in the mixture of lignocellulosic sugars. The highest acetic acid yield was obtained from sugarcane straw hydrolysate, with 71 % of theoretical yield based on total sugars (17 g/L acetic acid from 24 g/L total sugars). The lowest acetic acid yield was observed in forest residues hydrolysate, with 39 % of theoretical yield based on total sugars (18 g/L acetic acid from 49 g/L total sugars). Process derived compounds from steam explosion pretreatment, including 5-hydroxymethylfurfural (0.4 g/L), furfural (0.1 g/L) and total phenolics (3 g/L), did not inhibit microbial growth and acetic acid production yield. This research identified two major factors that adversely affected acetic acid yield in all hydrolysates, especially in forest residues: (i) glucose to xylose ratio and (ii) incomplete consumption of arabinose, galactose and mannose. For efficient bioconversion of lignocellulosic sugars to acetic acid, it is imperative to have an appropriate balance of sugars in a hydrolysate. Hence, the choice of lignocellulosic biomass and steam pretreatment design are fundamental steps for the industrial application of this process.     

植物木质素合成调控与生物质能源利用

植物木质素生物合成调控研究已在造纸树种与饲草品质的改良中取得了许多进展。随着对木质纤维原料乙醇发酵研究的兴起,植物木质素合成调控再次成为研究热点。该文总结了目前生物质能源利用的现状,同时针对木质素在木质纤维乙醇发酵中的限制作用,综述了近年来植物木质素合成调控的研究进展,提出了今后的研究方向和内容,并展望了木质素合成调控在木质纤维乙醇发酵中的应用。     

植物木质素合成调控与生物质能源利用

植物木质素生物合成调控研究已在造纸树种与饲草品质的改良中取得了许多进展。随着对木质纤维原料乙醇发酵研究的兴起, 植物木质素合成调控再次成为研究热点。该文总结了目前生物质能源利用的现状, 同时针对木质素在木质纤维乙醇发酵中的限制作用, 综述了近年来植物木质素合成调控的研究进展, 提出了今后的研究方向和内容, 并展望了木质素合成调控在木质纤维乙醇发酵中的应用。