Hydrolysis Of Corn Stalk Research Articles

Synergistic Effect of EtOAc/H2O Biphasic Solvent and Ru/C Catalyst for Cornstalk Hydrolysis Residue Depolymerization

An EtOAc/H2O biphasic solvent–Ru/C coupling biorefinery process was developed to selectively produce aromatics from cornstalk hydrolysis residue (CHR). In this process, CHR was depolymerized in an ethyl acetate (EtOAc)/H2O biphasic solvent system over Ru/C catalyst, which produced aromatics and carbohydrates instantly separated by EtOAc and H2O. Most lignin in CHR was converted to aromatics and nonvolatile fractions, accompanied with partial degradation of cellulose. Optimized results showed that more than 42.7% of aromatics can be obtained under 260 °C for 5 h without external hydrogen pressure. Monophasic and biphasic parallel experimental results show that the strong lignin dissolving ability of the biphasic dissolution/separation system is helpful for aromatics production and separation, which promoted CHR depolymerization over Ru/C. Furthermore, CHR, products, depolymeirzation residue solid (DRS), and catalysts were carefully characterized by gas chromatography (GC-MS), Fourier transform infrared (FT...

Recyclable magnetic carboxymethyl chitosan/calcium alginate – cellulase bioconjugates for corn stalk hydrolysis

The use of cellulase hydrolysis of straw to produce fermentable sugars has many application prospects. However, cellulase is very expensive, which hampers its industrial applications. To improve cellulase’s catalytic activity and reduce the enzyme cost, magnetite carboxymethyl chitosan/calcium alginate – cellulase bioconjugate (MCCCB) was synthesized via an improved hydrothermal method, molecular self-assembly technology, physical absorption, embedding and covalent bonding. Its loading capacity was 3.95mg/mL, and the catalytic activity increased to 267.18%. We decreased the release rate, improved the reusability, and enhanced the stability of MCCCB. Corn stalk hydrolysis also greatly improved, and the overall yield of fermentable sugars increased by 698.26%. All of these results indicate that MCCCB could significantly improve the efficiency of cellulase, greatly reduce the cost of enzyme, and effectively promote the production of fermentable sugars.

Synergistic Cellulose Hydrolysis Dominated by a Multi-Modular Processive Endoglucanase from Clostridium cellulosi.

Recalcitrance of biomass feedstock remains a challenge for microbial conversion of lignocellulose into biofuel and biochemicals. Clostridium cellulosi, one thermophilic bacterial strain dominated in compost, could hydrolyze lignocellulose at elevated temperature by secreting more than 38 glycoside hydrolases belong to 15 different families. Though one multi-modular endoglucanase CcCel9A has been identified from C. cellulosi CS-4-4, mechanism of synergistic degradation of cellulose by various cellulases from strain CS-4-4 remains elusive. In this study, CcCel9A, CcCel9B, and CcCel48A were characterized as processive endoglucanase, non-processive endoglucanase, and exoglucanase, respectively. To understand how they cooperate with each other, we estimated the approximate concentration ratio on the zymogram and optimized it using purified enzymes in vitro. Synergism between individual glycoside hydrolase during cellulose hydrolysis in the mixture was observed. CcCel9A and CcCel48A could degrade cellulose chain from non-reducing ends and reducing ends, respectively, to cello-oligosaccharide. CcCel9B could cut cellulose chain randomly and cello-oligosaccharides with varied length were released. In addition, a β-glucosidase BlgA from Caldicellulosiruptor sp. F32 which could cleave cello-oligosaccharides including G2-G6 to glucose was added to the enzyme mixture to remove the product inhibition of its partners. The combination and ratios of these cellulases were optimized based on the release rate of glucose. Hydrolysis of corn stalk was conducted by a four-component cocktail (CcCel9A:CcCel9B:CcCel48A:BlgA = 25:25:10:18), and only glucose was detected as main production by using high-performance anion-exchange chromatography. Processive endoglucanase CcCel9A, dominated in secretome of C. cellulosi, showed good potential in developing cellulase cocktail due to its exquisite cooperation with various cellulases.

An efficient process for lignin extraction and enzymatic hydrolysis of corn stalk by pyrrolidonium ionic liquids

In recent years, lignocellulosic biomass has drawn increasingly attention as a platform for its transformation into biofuels. However, the complex structures of lignocelluloses limit their conversion into fermentable sugars or other valuable products. In this work, a series of pyrrolidonium-based ionic liquids with a simple synthetic procedure were investigated for the pretreatment of corn stalk at 90°C for 30min. Both ionic liquids alone and ionic liquids with deionized water were studied. Fourier transform infrared spectroscopy (FTIR) analysis, scanning electron microscopy (SEM) analysis and nuclear magnetic resonance spectroscopy (NMR) analysis were employed to determine the chemical characteristics of regenerated lignin or cellulosic feedstock. A significant yield of lignin was achieved, as high as 19.07%, which accounted for 85.94% of the original lignin of corn stalk. A high yield of reducing sugar (91.81%) was obtained from regenerated cellulosic feedstock after enzymatic hydrolysis. High yields of glucose (79.63%) and cellobiose (13.66%) were observed as determined by high performance liquid chromatography (HPLC).

Expression of feruloyl esterase A from Aspergillus terreus and its application in biomass degradation

Feruloyl esterases (FAEs) are key enzymes involved in the complete biodegradation of lignocelluloses, which could hydrolyze the ester bonds between hemicellulose and lignin. The coding sequence of a feruloyl esterase A (AtFaeA) was cloned from Aspergillus terreus and the recombinant AtFaeA was constitutively expressed in Pichia pastoris. The SDS–PAGE analysis of purified AtFaeA showed two protein bands owing to the different extent of glycosylation, and the recombinant AtFaeA had an optimum temperature of 50°C and an optimum pH of 5.0. The substrate utilization and primary sequence identity of AtFaeA demonstrated that it is a type-A feruloyl esterase. The hydrolysis of corn stalk and corncob by xylanase from Aspergillus niger could be significantly improved in concert with recombinant AfFaeA.

Optimization design to study the effect of acid-catalyzed hydrolysis of corn stalk using severity and statistical model for high solid and liquid phase recovery

In this research, the effects of combined severity parameters (CSP), response surface methodology (RSM), and separation factor (SF) on the recovery and/or removal rate of main fraction for acid-catalyzed hydrolysis of corn stalk were defined and investigated. The results demonstrated that the maximum total sugar yield (44.31 wt%) was obtained from corn stalk after hydrolysis with 2.05 wt% of acid catalysis at 113.17 °C for 61.69 min (CSP0 = 1.80) while the high glucan recovery (88.02%), de-pentosane rate (97.21%), and SF of solid phase fraction were obtained with CSP0 range of 1.14–2.18 (CSP1 range of 1.80–2.82). The findings suggest that CSP1 can be used to more efficiently evaluate the separation degree of glucan with lignin (SFG-L) than CSP0. The acid-catalyzed hydrolysis of corn stalk has an advantage of high solid–liquid phase recovery and CSP can be used to describe the effect of acid hydrolysis.

Performance and microbial community of carbon nanotube fixed-bed microbial fuel cell continuously fed with hydrothermal liquefied cornstalk biomass

Hydrothermal liquefaction (HTL) is a green technology for biomass pretreatment with the omission of hazardous chemicals. This study reports a novel integration of HTL and carbon nanotubes (CNTs) fixed-bed microbial fuel cell (FBMFC) for continuous electricity generation from cornstalk biomass. Two FBMFCs in parallel achieved similar performance fed with cornstalk hydrolysate at different organic loading rates (OLRs) (0.82–8.16g/L/d). About 80% of Chemical oxygen demand (COD) and Total organic carbon (TOC) was removed from low-Biochemical oxygen demand (BOD)/COD (0.16) cornstalk hydrolysate at 8.16g/L/d, whereas a maximum power density (680mW/m3) was obtained at 2.41g/L/d, and a smallest internal resistance (Rin) (28Ω) at 3.01g/L/d. Illumina MiSeq sequencing reveals the diverse microbial structure induced by the complex composition of cornstalk hydrolysate. Distinguished from Proteobacteria, which a number of exoelectrogens belong to, the identified dominant genus Rhizobium in FBMFC was closely related to degradation of cellulosic biomass.

Comparative Evaluation of Reducing Sugar Yields Produced from Corn Cob and Corn Stalk Hydrolysis usingAspergillus Niger

Over the years, managing agricultural wastes after harvest in developing countries like Nigeria has been a major challenge and continues to generate environmental concerns. To address the concerns, these agricultural wastes in the form of lignocellulosic biomass are burned. This approach, in turn, had led to a greater environmental interest as emission of green house gases to the atmosphere is increased. The attendant implications of this are significant contribution to ozone layer depletion and elimination of soil microflora present. Interestingly, these wastes are potential precursors for biofuel production. This study was undertaken to investigate the reducing sugar (RS) yields of two lignocellulosic biomass wastes (corn stalk and corn cob) as biofuel precursors. The findings of the study showed that the optimal RS yields as product of hydrolysis using Aspergillus niger isolated from soil after 72 h of hydrolysis were 2.9 mg/ml and 3.0 mg/ml for corn cob and corn stalk, respectively.

An Efficient Process for Pretreatment of Lignocelluloses in Functional Ionic Liquids

Background and Aims. The complex structure of the lignocelluloses is the main obstacle in the conversion of lignocellulosic biomass into valuable products. Ionic liquids provide the opportunities for their efficient pretreatment for biomass. Therefore, in this work, pretreatment of corn stalk was carried out in ultrasonic-assisted ionic liquid including 1-butyl-3-methylimidazolium chloride [BMIM]Cl, 1-H-3-methylimidazolium chloride [HMIM]Cl, and 1-(1-propylsulfonic)-3-imidazolium chloride [HSO3-pMIM]Cl at 70°C for 2 h. We compared the pretreatments by ionic liquid with and without the addition of deionized water. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were employed to analyze the chemical characteristics of regenerated cellulose-rich materials.Results. [HMIM]Cl and [HSO3-pMIM]Cl were effective in lignin extraction to obtain cellulose-rich materials. FTIR analysis and SEM analysis indicated the effective lignin removal and the reduced crystallinity of cellulose-rich materials. Enzymatic hydrolysis of cellulose-rich materials was performed efficiently. High yields of reducing sugar and glucose were obtained when the corn stalk was pretreated by [HMIM]Cl and [HSO3-pMIM]Cl.Conclusions. Ionic liquids provided the ideal environment for lignin extraction and enzymatic hydrolysis of corn stalk and [HMIM]Cl and [HSO3-pMIM]Cl proved the most efficient ionic liquids. This simple and environmentally acceptable method has a great potential for the preparation of bioethanol for industrial production.

Effect of acetylation/deacetylation on enzymatic hydrolysis of corn stalk

Effect of degree of acetylation (DA) within corn stalk (CS) on the enzymatic hydrolysis was investigated. By acetylation and deacetylation treatment, CS with different DA from 0.34% to 11.20% was prepared. The analysis of chemical composition by two-step acid hydrolysis and characteristic functional groups via FTIR implied that the structure of the three major components (cellulose, hemicellulose and lignin) in the treated CS was not changed noticeably. The correlation between enzymatic yield and DA was navigated well by the nonlinear curve fit with Adj. R-Square greater than 0.90. The DA was proved to be a crucial barrier to the digestibility of CS. The efficiency of the enzymatic hydrolysis was negatively correlated with DA value.

Succinic acid production from hemicellulose hydrolysate by an Escherichia coli mutant obtained by atmospheric and room temperature plasma and adaptive evolution

Atmospheric and room temperature plasma and adaptive evolution were combined to generate Escherichia coli mutants, which can simultaneously and efficiently utilize glucose and xylose to produce succinic acid in chemically defined medium under exclusively anaerobic condition. Compared to the parent strain BA305, a pflB, ldhA, ppc, and ptsG deletion strain overexpressing ATP-forming phosphoenolpyruvate (PEP) carboxykinase (PEPCK), the sugar consumption rate and succinic acid productivity of mutant BA408 were significantly improved with a marked increase in the key enzyme activities. Subsequent anaerobic fermentation of BA408 with corn stalk hydrolysate produced a final succinic acid concentration of 23.1gL−1 with a yield of 0.85gg−1 sugar mixture. The observed synthesis of succinic acid from the corn stalk hydrolysate showed a great potential usage of renewable biomass as a feedstock for an economical succinic acid production using E. coli.

An anaerobic sequential batch reactor for enhanced continuous hydrogen production from fungal pretreated cornstalk hydrolysate

Anaerobic sequencing batch reactor (ASBR) process offers great potential for H2 production from wastewaters. In this study, an ASBR was used at first time for enhanced continuous H2 production from fungal pretreated cornstalk hydrolysate by Thermoanaerobacterium thermosaccharolyticum W16. The reactor was operated at different hydraulic retention times (HRTs) of 6, 12, 18, and 24 h by keeping the influent hydrolysate constant at 65 mmol sugars L−1. Results showed that increasing the HRT from 6 to 12 h led to the H2 production rate increased from 6.7 to the maximum of 9.6 mmol H2 L−1 h−1 and the substrate conversion reached 90.3%, although the H2 yield remained at the same level of 1.7 mol H2 mol−1 substrate. Taking into account both H2 production and substrate utilization efficiencies, the optimum HRT for continuous H2 production via an ASBR was determined at 12 h. Compared with other continuous H2 production processes, ASBR yield higher H2 production at relatively lower HRT. ASBR is shown to be another promising process for continuous fermentative H2 production from lignocellulosic biomass.

Using a statistical approach to model hydrogen production from a steam exploded corn stalk hydrolysate fed to mixed anaerobic cultures in an ASBR

In this study, hydrogen (H2) production from the fermentation of steam exploded corn stalk (CS) liquor was statistically optimized using a fractional factorial design approach. The factors under consideration included temperature, pH and hydraulic retention time (HRT). Under optimal conditions at 53 °C, a pH at 4.5 and a 9.5 h HRT, the observed maximum H2 yield of 98 ± 2 mL g−1 TVS together with negligible CH4 were similar to the model predicted responses. A flux analysis revealed negligible homoacetogenic activity in cultures at 53 °C and low pH (≤5.5). Both homoacetogenic (R17) and methanogenic (R28 and R29) fluxes accounted for more than 68–90% of H2 consumption in cultures at low temperatures. The low H2 yields observed in cultures maintained at 21 °C and 37 °C was associated with high lactate and solvent levels. High H2 yields in cultures at 53 °C were associated with a higher abundance of Clostrdium sp. and CH4 production at low temperatures was due to the presence of hydrogenotrophic methanogens (Methanothermobacter marburgensis and Methanobrevibacter ruminatum) and aceticlastic methanogens (Methanosaeta sp. and Methanosarcina sp.). The results obtained from this study (within the factor ranges investigated) indicated that steam exploded CS liquor could be a potential substrate for H2 production using mixed microbial cultures.

Extremely Low Sulfuric Acid Hydrolysis of Cornstalk and Its Structural Changes

Science and Technology Program from Science Technology Department of Zhejiang Provincial of China [2012C322080]; science and technology planning Program from Zhejiang Environmental Protection Bureau of China [2012B008]; 521 talent cultivation plan of Zhejiang Sci-Tech University, Science Foundation of Zhejiang Sci-Tech University (ZSTU) [1101821-Y]; open fund of Key Laboratory of Biomass Energy and Material of China [JSBEM201303]; open fund of Key Laboratory of Pulp and Paper Science and Technology of Ministry of Education of China [KF201200]; National Key Basic Research Program from the Ministry of Science and Technology of China [2010CB732201]; Natural Science Foundation of China [2106121, U0733001]; Basic Foundation for Scientific Research of Universities from the Ministry of Education of China [2010121077]; Provincial R&D Program from Economic and Trade Committee of Fujian Province of China [1270-K42004]

Succinic acid production from corn stalk hydrolysate in anE. colimutant generated by atmospheric and room-temperature plasmas and metabolic evolution strategies

AFP111 is a spontaneous mutant of Escherichia coli with mutations in the glucose-specific phosphotransferase system, pyruvate formate lyase system, and fermentative lactate dehydrogenase system, created to reduce byproduct formation and increase succinic acid accumulation. In AFP111, conversion of xylose to succinic acid only generates 1.67 ATP per xylose, but requires 2.67 ATP for xylose metabolism. Therefore, the ATP produced is not adequate to accomplish the conversion of xylose to succinic acid in chemically defined medium. An E. coli mutant was obtained by atmospheric and room-temperature plasmas and metabolic evolution strategies, which had the ability to use xylose and improve the capacity of cell growth. The concentration of ATP in the mutant was 1.33-fold higher than that in AFP111 during xylose fermentation. In addition, under anaerobic fermentation with almost 80% xylose from corn stalk hydrolysate, a succinic acid concentration of 21.1gl(-1) was obtained, with a corresponding yield of 76%.

Co-expression of phosphoenolpyruvate carboxykinase and nicotinic acid phosphoribosyltransferase for succinate production in engineered Escherichia coli

Succinate is not the dominant fermentation product from xylose in wild-type Escherichia coli K12. E. coli BA 203 is a lactate dehydrogenase (ldhA), pyruvate formate lyase (pflB), and phosphoenolpyruvate (PEP)-carboxylase (ppc) deletion strain. To increase succinate accumulation and reduce byproduct formation, engineered E. coli BA204, in which ATP-forming PEP-carboxykinase (PEPCK) is overexpressed in BA203, was constructed and produced 2.17-fold higher succinate yield. To further improve the biomass and the consumption rate of xylose, nicotinic acid phosphoribosyltransferase (NAPRTase), a rate limiting enzyme in the synthesis of NAD(H), was also overexpressed. Thus, co-expression of PEPCK and NAPRTase in recombinant E. coli BA209 was investigated. In BA209, the pck gene and the pncB gene each have a trc promoter, hence, both genes are well expressed. During a 72-h anaerobic fermentation in sealed bottles, the total concentration of NAD(H) in BA209 was 1.25-fold higher than that in BA204, and the NADH/NAD+ ratio decreased from 0.28 to 0.11. During the exclusively anaerobic fermentation in a 3-L bioreactor, BA209 consumed 17.1gL−1 xylose and produced 15.5gL−1 succinate. Furthermore, anaerobic fermentation of corn stalk hydrolysate contained 30.1gL−1 xylose, 2.1gL−1 glucose and 1.5gL−1 arabinose, it produced a final succinate concentration of 17.2gL−1 with a yield of 0.94gg−1 total sugars.

Improvement of kojic acid production in Aspergillus oryzae B008 mutant strain and its uses in fermentation of concentrated corn stalk hydrolysate

A strain designated M866, producing kojic acid with a high yield, was obtained by combining induced mutation using ion beam implantation and ethyl methane sulfonate treatment of a wild type strain of Aspergillus oryzae B008. The amount of kojic acid produced by the strain M866 in a shaking flask was 40.2 g/L from 100 g/L of glucose, which was 1.7 times higher than that produced by wild strain (23.58 g/L). When the mixture of glucose and xylose was used as carbon source, the resulting kojic acid production was raised with the increasing of glucose ratios in the mixture. With concentrations of glucose at 75 g/L and xylose at 25 g/L mixed in the medium, the production of kojic acid reached 90.8 %, which was slightly lower than with glucose as the sole source of carbon. In addition, the kojic acid fermentation of the concentrated hydrolysate from corn stalk was also investigated in this study, the maximum concentration of kojic acid accumulated at the end of the fermentation was 33.1 g/L and this represents the yield based on reducing sugar consumed and the overall productivity of 0.36 g/g and 0.17 g/L/h, respectively.

Evaluation of continuous biohydrogen production from enzymatically treated cornstalk hydrolysate

Enzymatically treated cornstalk hydrolysate was tested as substrate for H2 production by Thermoanaerobacterium thermosaccharolyticum W16 in a continuous stirred tank reactor. The performance of strain W16 to ferment the main components of hydrolysate, mixture of glucose and xylose, in continuous culture was conducted at first, and then T. thermosaccharolyticum W16 was evaluated to ferment fully enzymatically hydrolysed cornstalk to produce H2 in continuous operation mode. At the dilution rate of 0.020 h−1, the H2 yield and production rate reached a maximum of 1.9 mol H2 mol−1 sugars and 8.4 mmol H2 L−1 h−1, respectively, accompanied with the maximum glucose and xylose utilizations of 86.3% and 77.6%. Continuous H2 production from enzymatically treated cornstalk hydrolysate in this research provides a new direction for economic, efficient, and harmless H2 production.

Enzymatic saccharification of cornstalk by onsite cellulases produced byTrichoderma viridefor enhanced biohydrogen production

Lignocellulosic biomass, if properly saccharified, could be an ideal feedstock for biohydrogen production. However, the high cellulases cost is the key obstacle to its development. In this work, cost-effective enzyme produced by Trichoderma viride was used to saccharify cornstalk. To obtain high sugar yield, a central composite design of response surface method was used to optimize enzymatic saccharification process. Experimental results showed that the enzymatic saccharification rate reached the highest of 81.2% when pH, temperature, cellulases and substrate concentration were 5, 49.7 °C, 35.7 IU g−1, and 38.5 g L−1, respectively. The cornstalk hydrolysate was subsequently introduced to fermentation by Thermoanaerobacterium thermosaccharolyticum W16, the yield of hydrogen reached the highest level of 90.6 ml H2 g−1 pretreated cornstalk. The present results indicate the potential of using T. thermosaccharolyticum W16 for high yield conversion of cornstalk hydrolysate, which was saccharified by onsite enzyme produced by T. viride.

Hydrolysis Kinetics of Cornstalk in Formic Acid Solution

Cornstalk, among the agricultural residues and other non-wood fiber, is a more promising source of lignocellulosic materials for bioethanol production. Pretreatment is an essential step in the enzymatic hydrolysis of biomass and subsequent production of bioethanol. Kinetic models can have practical applications for the optimization of the process and performance analysis, or economic estimations, so investigate the cornstalk hydrolysis kinetics is necessary. In this paper, effects of temperature and time on cornstalk hydrolysis in saturated formic acid with 4% hydrochloric acid solution reaction kinetics have been investigated. The results showed that the hydrolysis velocities of cornstalk were 0.021 h−1 at 60 °C, 0.0302 h−1 at 65 °C and 0.060 h−1 at 70 °C, the degradation velocities of glucose were 0.061 h−1 at 60 °C, 0.0845 h−1 at 65 °C, and 0.24 h−1 at 70 °C, the activation energy of cornstalk hydrolysis was 99.60 kJ/mol, and the activation energy of glucose degradation was130.94 kJ/mol.