Monosaccharide Yield Research Articles

Pilot scale sulfur dioxide-ethanol-water fractionation of recycled wood to sugars, bioethanol, lignin and lignosulfonates: Carbohydrate balance

Two grades of recycled wood (Waste Wood A and Waste Wood B) were fractionated on a pilot scale (800 BD kg) to monomeric sugars, lignin and lignosulfonates using SO2-Ethanol-Water (AVAP®) technology, including pretreatment, separation of cellulosic and hemicellulosic streams, and saccharification. Carbohydrate mass balance was obtained through determination of poly-, oligo- and monosaccharides as well as sugar degradation products in process streams. High monosaccharide yields were obtained confirming laboratory scale findings. Fermentability of mixed cellulosic and hemicellulosic sugar stream was confirmed on bench scale (25 kg).

Utilization of the acid hydrolysate of defatted Chlorella biomass as a sole fermentation substrate for the production of biosurfactant from Bacillus subtilis C9

Although algal biofuels have been promoted as a carbon-neutral alternative to fossil fuels, several economic and technological barriers challenge the much-anticipated success of algae as a commercial bio-feedstock. In particular, utilizing only a lipid portion of harvested algal biomass limits possible monetary returns from algal biomass within which non-lipid compounds generally comprise a major proportion. Previous studies thus demonstrated the production of ethanol from defatted algal biomass to improve overall economic outlook of the nascent algae industry; however, it is also possible to utilize residual algal biomass as a fermentation substrate for bacterial strains producing high value alternative products. Therefore, the goal of this study was to compare the yield of biosurfactant from B. subtilis C9 in conventional culture medium and the acid hydrolysate of defatted Chlorella biomass (DCB). Although increasing the concentration of acid catalyst from 0 N to 1.0 N was expected to proportionally enhance the effectiveness of dilute acid hydrolysis, the results indicated that DCB hydrolysates treated under different acid conditions at 121 °C for 15 min exhibited the highest yield of fermentable monosaccharides when treated with 0.25 N HCl. Subsequently, the fermentation of B. subtilis C9 was performed in both Luria-Bertani (LB) and DCB hydrolysate medium after adjusting salinity and monosaccharide concentration to identical levels; a significantly greater yield of biosurfactant was observed in the culture grown with DCB hydrolysate medium, while the presence of magnesium and manganese co-factors in DCB hydrolysate contributed to a greater biosurfactant yield. Collectively, these results suggest that the valorization of defatted algal biomass could be also accomplished by incorporating biosurfactant fermentation into algal biorefinery processes and call for further process optimization efforts that consider factors associated with the operation of industrial algal biorefineries.

High level production of a Bacillus amlyoliquefaciens chitosanase in Pichia pastoris suitable for chitooligosaccharides preparation

Chitooligosaccharides (COS) are hydrolytic products of chitosan that are essential in functional food, medicine, and other fields due to their biological activities. Commercial COS are often prepared by the hydrolysis of chitosan by chitosanase. In this study, a glycoside hydrolase family 46 cluster B chitosanase from Bacillus amyloliquefaciens (BaCsn46B) was efficiently expressed in Pichia pastoris. The recombinant enzyme was secreted into the culture medium that reached a total extracellular protein concentration of 4.5 g/L with an activity of 8907.2 U/mL in a high cell density fermenter (5 L). The molecular mass of deglycosylated BaCsn46B was 29.0 kDa. Purified BaCsn46B exhibited excellent enzymatic properties, which had high specific activity (2380.5 U/mg) under optimal reaction conditions (55 °C and pH 6.5). BaCsn46B hydrolyzed chitosan yielded a series of COS with different degrees of polymerization by endo-type cleavage. The end hydrolytic products of BaCsn46B were chitobiose and chitotriose, while no monosaccharide yield was evident in the hydrolytic reaction. The excellent secreted expression level and hydrolytic performance make the enzyme a desirable biocatalyst for the industrial preparation of COS.

Sulfur dioxide-ethanol-water fractionation platform for conversion of recycled wood to sugars, lignin and lignosulfonates

Recycled wood of two grades (A and B) and spruce were converted on bench (100 o.d. g) and pilot (100 o.d. kg) scales to monosugars, lignin and lignosulfonates using SO2-Ethanol-Water (AVAP®) technology. After digestion, C6 and C5 sugars were recovered at 98–100% and 87–99% for Wood A and Spruce, respectively, while the values for Wood B were 92% and 74–87%. Cellulose was hydrolysed to glucose at 90% or higher using enzyme charge of 7.1 FPU/g glucan. Hemicellulosic sugars were autohydrolyzed to 95–100% monosugars.At bench scale, monosaccharide yield was 609, 561 and 688 kg (hydrous) per BDT biomass for Wood A, Wood B and Spruce, respectively. Corresponding water insoluble lignin yield was 157, 148 and 189 kg per BDT biomass. The preliminary techno-economic evaluation revealed that conversion of recycled wood to sugars using AVAP® fractionation platform results in higher profitability in comparison to virgin wood.

Enhanced Enzymatic Hydrolysis and Lignin Extraction of Wheat Straw by Triethylbenzyl Ammonium Chloride/Lactic Acid-Based Deep Eutectic Solvent Pretreatment.

Efficient and feasible pretreatment of lignocellulosic biomass waste is an important prerequisite step to promote subsequent enzymatic hydrolysis and enhance the economics of biofuels production. This study focuses on the pretreatment of wheat straw (WS) with triethylbenzyl ammonium chloride/lactic acid (TEBAC/LA)-based deep eutectic solvents to enhance biomass fractionation and lignin extraction. Effects of pretreatment time, temperature, and TEBAC/LA molar ratio on pretreatment were evaluated systematically. Results suggested that 89.06 ± 1.05% of cellulose and 71.00 ± 1.03% of xylan were hydrolyzed with enzyme loadings of 35 FPU cellulase and 82 CBU β-glucosidase (per gram of dry biomass) after pretreatment by TEBAC/LA (1:9) at 373 K for 10 h. A total monosaccharide yield of 0.550 g/g WS (91.27% of the theoretical yield) was achieved with 79.73 ± 0.93% of lignin removal. Furthermore, the 1H–13C two-dimensional heteronuclear single quantum correlation (2D-HSQC) NMR spectroscopy showed that the regenerated lignin (75.69 ± 1.32% purity) was mainly composed of the syringyl units and the guaiacyl units. Overall, the results in this study provide an effective and facile pretreatment method for lignocellulosic biomass waste to enhance enzymatic hydrolysis saccharification.

Biohydrogen from Sugarcane Bagasse Pretreated with Combined Alkaline and Ionic Liquid [DMIM]DMP

Biohydrogen attracts many attentions since it has many advantages as source of energy. Biohydrogen from sugarcane bagasse offers many advantages from economic and environmental point of view. This work aimed to study the production of hydrogen from sugarcane bagasse through enzymatic hydrolysis and fermentation using Enterobacter aerogenes . Pretreatment with ionic liquid [DMIM]DMP was carried out prior to hydrolysis. It was found that process with ionic liquid was able to shift the cellulose structure from crystalline cellulose to more amorphous cellulose. Alkaline pretreatment followed by ionic liquid conducted for 20 min at 120 o C gave the lowest crystallinity index. This condition also gave the highest total recovery of cellulose and hemicellulose, a condition that is very important for enzymatic hydrolysis to produce as much sugar as possible. Pretreatment condition was also found to give significant effect to the yield and type of monosaccharides produced from the hydrolysis process. Optimization of the pretreatment condition of the combined alkaline and ionic liquid [DMIM]DMP pretreatment was found to give significant effect to the ease of lignocellulosic substrate for its conversion to reducing sugar. The yield of hydrogen from the fermentation of the obtained sugar was 0.46 mole H 2 per mole of glucose consumed.

Ethanol production by simultaneous saccharification and cofermentation of pretreated corn stalk.

The recalcitrance of lignocellulosic biomass is a major factor limiting its conversion into biofuels. Therefore, in this study, we pretreated corn stalk with 2% Na2 CO3 and 2% H2 O2 for time 70 min at 130°C using a corn stalk to liquid ratio of 1:10. The fermentation broth from multicopy Saccharomyces cerevisiae strains engineered for lignocellulase synthesis was used to enzymatically hydrolyze the pretreated corn stalk. The highest monosaccharide yield (102 mmol/L) was obtained using 15 IU endocellulase, 10 IU exocellulase, and 15 IU β-glucosidase per gram of cellulose and 20 IU xylanase per gram of hemicellulose. Subsequently, the high-efficiency ethanol-producing S. cerevisiae strain WXY12, which can produce ethanol from glucose and xylose simultaneously, was added to the fermentation system. The entire process involved ethanol production through simultaneous saccharification and fermentation (SSF). Optimization of the fermentation conditions (yeast powder as a nitrogen source, temperature of 30°C, MgSO4 as a metal ion inducer, rotation speed of 180 rpm, solid-liquid ratio of 1:8, and inoculation amount of 2%) resulted in an ethanol output of 46.87 g/L and a theoretical conversion rate of 27.4%. The results of this study improved corn stalk utilization, reduced hydrolysis costs, and generated high ethanol yields.

Directional liquefaction of lignocellulosic biomass for value added monosaccharides and aromatic compounds

Using lignocellulosic biomass as a feedstock for sustainable production of platform molecules is of great significance. We examined the directional liquefaction coupled with efficient stepwise fractionation of bamboo biomass into two groups of chemicals: monosaccharides and aromatic products. When sulfuric acid was used as the catalyst, a conversion of 70% was achieved with a 40% yield of monosaccharides and a 20% yield of aromatics were obtained at 180 °C for 30 min when the catalyst loading was 3.0% per 6.0 g bamboo. The production of 5-hydroxymethylfural (HMF), 5-ethoxymethylfurfural (EMF), ethyl levulinate (EL) and furfural was analyzed in terms of by-products formation. Due to similar physiochemical properties in each fraction, the platform molecules could broaden a new paradigm of bamboo biomass utilization for renewable energy and value-added biochemicals.

Selective Conversion of Hemicellulose in Macroalgae Enteromorpha prolifera to Rhamnose.

Direct hydrothermal conversion (HC) of macroalgae Enteromorpha prolifera was conducted over the temperature range of 140–240 °C. At 160 °C, monosaccharides and small molecular acids began to generate. A high yield (18.8%) of monosaccharides was obtained at 180 °C, whereas 29.6% of small molecular organic acids was attained at 200 °C. Formic acid (FA) was then employed as a catalyst, which could selectively catalyze the conversion of hemicellulose at low temperature (94.1%, 140 °C). Rhamnose (45.2%) based on the mass of carbohydrates in E. prolifera was produced by the catalysis of 0.7 mL of FA (160 °C, 60 min, 1 g of biomass loading). A low ratio of biomass amount to water was beneficial to the solution of water-soluble components of hemicellulose in E. prolifera to get high yields to monosaccharides. HC showed promise to be an applicable and efficient method in the treatment of E. prolifera with high conversion of carbohydrates.

Pectin and Neutral Monosaccharides Production during the Simultaneous Hydrothermal Extraction of Waste Biomass from Refining of Sugar-Optimization with the Use of Doehlert Design.

We propose a one-stage hydrothermal extraction of sugar beet pulp leading to effective co-production of pectin and neutral monosaccharides with a relatively high yield and satisfactory purity without the presence of an acidic catalyst. The optimal experimental design methodology was used for modelling and optimizing the yield of pectin and neutral monosaccharides. In good agreement with experimental results (R2 = 0.955), the model predicts an optimal yield of pectin (approx. 121.1 g kg−1 ± 0.47 g kg−1) at a temperature and time of about 118.1 °C and 21.5 min, respectively. The highest yield of the sum of neutral monosaccharides (approx. 82.6 g kg−1 ± 0.72 g kg−1) was obtained at about 116.2 °C and 26.4 min (R2 = 0.976). The obtained results are suitable for industrial upscaling and may provide an incentive to implement a new, environmentally friendly, simple, and effective method for treating waste product from the sugar refining industry, which has proved onerous until now.

Influence of the pretreatment method on the hydrolysis of cassava starch factory residue

Cassava starch factory residue (CSFR) is an attractive lignocellulosic material for bioethanol production because it is one of the most abundant renewable resources. The purpose of this work was to investigate the technical feasibility of converting CSFR into fermentable sugars using 12 different pretreatment methods. The yields of monosaccharides, oligosaccharides, and total sugars present in the hydrolysates obtained from the different pretreatment methods were examined by transferring the solid organic matter present to a liquid phase. We found that pretreatment with a dilute acid was superior to both alkaline and hot water pretreatment methods, while combined chemical‐enzymatic pretreatment was superior to single enzymatic pretreatment. More specifically, treatment with a dilute acid was conducive to the formation of monomeric sugars, whereas single enzyme pretreatment and high‐temperature alkaline pretreatment methods were conducive to the formation of oligomeric sugars. Pretreatment with 0.5% (w/v) HNO3 (160 °C, 10 min) gave the highest total monosaccharide concentration (i.e., 25,827 mg/L) with a yield of 30.99%, whereas hemicellulose (45 U/g CSFR) + cellulose (120 U/g CSFR) pretreatment gave the highest total oligosaccharide concentration (i.e., 22,152 mg/L) with a yield of 26.69%. Finally, pretreatment with 1% (w/v) H2SO4 (121 °C, 40 min) + hemicellulose (120 U/g CSFR) + cellulose (120 U/g CSFR) gave the highest total sugar concentration (i.e., 43,196 mg/L) with a yield of 51.84%. © 2018 American Institute of Chemical Engineers Environ Prog, 38: 624–629, 2019

The additive free microwave hydrolysis of lignocellulosic biomass for fermentation to high value products

Abstract Current biorefineries are predominantly based around single feedstock sources, extensively hydrolysed using multiple unit operations. The hydrolysate is generally converted to a single product by one of a few well-characterised organisms. Here, we report on a new approach to the biorefinery, combining a rapid, microwave heated, one-step depolymerisation process, with a yeast, Metschnikowia pulcherrima which is able to metabolise an array of oligo- and monosaccharides. During the investigation it was found that the microwave hydrolysis process was able to solubilize upto 50% wheat straw biomass by weight, mainly as oligosaccharides though also containing mixtures of pentose, hexose and anhydro-sugars with concentrations of up to 2 g L-1. However, a fine balance between elevated monosaccharide yields and the production of inhibitive compounds had to be struck with optimal microwave hydrolytic conditions found to be 190 °C. Further testing utilizing several different types of lignocellulosic biomass demonstrated it was possible to attain ~65% carbon efficiency in the conversion of Laminaria saccharina to hydrolysis products. The system was scaled to 600 mL using DDGS successfully solubilizing 66% of the feedstock, producing 33 g L-1 hydrolysate. M. pulcherrima grew well on this hydrolysate in a controlled stirred tank bioreactor (2L), yielding 8.38 g L-1 yeast biomass, a yeast biomass coefficient of 0.25. This presents an exciting, feedstock agnostic, pathway to the energy efficient production of a wide variety of commercially valuable chemical products without the need for extensive pre and post processing technologies.

Ammonium sulfite pretreatment of wheat straw for efficient enzymatic saccharification

Pretreatment is an important upstream process that affects the economics of biofuels production from lignocellulose. This study established a novel pretreatment process for efficient bioconversion of wheat straw using ammonium sulfite as pretreatment option. Effects of temperature, time, ammonium sulfite concentration and sodium carbonate supplementation level on pretreatment were evaluated. 99.9% of glucan and 88.0% of xylan were hydrolyzed with 35 FPU cellulase and 70 FXU xylanase (per gram of dry biomass) in 24 h after pretreatment by 20% (w/w) ammonium sulfite supplemented with 4% (based on ammonium sulfite dosage) sodium carbonate at 180 °C for 1 h. Total monosaccharide yield of 0.413 g/g native wheat straw was achieved with 82.6% acid insoluble lignin removal. Characterization results of flourier translation infrared spectrum revealed that lignin can be removed by sulfonation and ammonolysis. The results in the research provide an efficient method for lignocellulose pretreatment.

Acetone–butanol–ethanol fermentation of non-detoxified dilute acid extracted hemicellulosic hydrolysate from the short-rotation coppice Salix schwerinii E. Wolf

The dilute acid-catalyzed extraction of hemicellulosic monosaccharides from the short-rotation coppice Salix schwerinii E. Wolf was optimized to find a balance between the yields of fermentable monosaccharides and sugar degradation products for non-detoxified acetone-butanol-ethanol fermentation with Clostridium acetobutylicum. At the same time, the cellulosic and lignin fractions were kept as intact as possible for further refining. The highest xylose and glucose yields in the liquid prehydrolysate were 65% and 9.45% of their respective original content at a combined severity of 2.29. Increased concentrations of glucose and sugar degradation products in the liquid prehydrolysates were detected with an increasing pretreatment temperature and combined severity, while the acid-insoluble lignin remained stable. During the fermentation of the non-detoxified liquid prehydrolysate with grain starch as the supplement, 66% of the xylose was utilized, and the butanol and acetone-butanol-ethanol yields were 0.22 g/g and 0.35 g/g monosaccharides, respectively, in the fermentation medium. The results suggested that the hemicellulose in S. schwerinii can be separately extracted as a side stream and utilized for butanol fermentation with starch-based materials without a separate detoxification stage.

High monomeric sugar yields from enzymatic hydrolysis of soybean meal and effects of mild heat pretreatments with chelators

Defatted soybean meal has 30–35% oligo-/polymeric carbohydrates and approximately 50% proteins. Enzymatic carbohydrate monomerization enables easy separation to enrich protein content, reduces indigestibility concerns, and facilitates use of carbohydrate as fermentation feedstock. Among soybean carbohydrates, pectin and glucan are more recalcitrant to hydrolyze. To destabilize Ca2+-bridged junctures in pectin, effects of 3 chelators ethylenediaminetetraacetic acid (EDTA), sodium hexametaphosphate (HMP) and citric acid under 2-h 90 °C pretreatments were investigated here. Citric acid was the most effective while EDTA decreased enzymatic hydrolysis. In a 3-factor 2-level factorial study, heat (90 °C, 2 h) and citric acid (10 g/L) pretreatments and cellulase supplementation (10 FPU/g) were found to increase yields of all monosaccharides, to 86.8 ± 5.2% glucose, 98.1 ± 1.6% xylose, 87.5 ± 5.2% galactose, 83.6 ± 1.6% arabinose, and 91.4 ± 3.1% fructose + mannose. The largest percentage improvements were for arabinose (382%), mannose (113%) and glucose (51%). Achieving high monosaccharide yields greatly increases value of soybean carbohydrate as fermentation feedstock.

Subcritical water hydrolysis of sugar beet pulp towards production of monosaccharide fraction

Sugar beet pulp represents one of the most abundant by-product in food industry in terms of underexploited opportunities and amounts produced. In order to produce added-value product from this lignocellulosic material, subcritical water hydrolysis was applied in this study. Response surface methodology was used to evaluate the effects of hydrolysis parameters and optimize conditions for various responses. Hydrolysis temperature, hydrolysis time and HCl concentration were investigated as independent variables. The results obtained indicated highly promising application of corresponding hydrolysis technique towards valorization of proposed raw material. Relatively high yield of fermentable sugars with the addition of acid agent and the higher hydrolysis rates of lignocellulosic material compared to the previously published studies were obtained. Hydrolysis efficiency was higher than 50% and total monosaccharide yield reached up to 5.669 mg/mL which is significantly higher than previously reported results.

Concept for Recycling Waste Biomass from the Sugar Industry for Chemical and Biotechnological Purposes.

The objective of this study was to develop a method for the thermally-assisted acidic hydrolysis of waste biomass from the sugar industry (sugar beet pulp and leaves) for chemical and biotechnological purposes. The distillates, containing furfural, can be catalytically reduced directly into furfurayl alcohol or tetrahydrofurfuryl alcohol. The sugars present in the hydrolysates can be converted by lactic bacteria into lactic acid, which, by catalytic reduction, leads to propylene glycol. The sugars may also be utilized by microorganisms in the process of cell proliferation, and the biomass obtained used as a protein supplement in animal feed. Our study also considered the effects of the mode and length of preservation (fresh, ensilage, and drying) on the yields of furfural and monosaccharides. The yield of furfural in the distillates was measured using gas chromatography with flame ionization detector (GC-FID). The content of monosaccharides in the hydrolysates was measured spectrophotometrically using enzymatic kits. Biomass preserved under all tested conditions produced high yields of furfural, comparable to those for fresh material. Long-term storage of ensiled waste biomass did not result in loss of furfural productivity. However, there were significant reductions in the amounts of monosaccharides in the hydrolysates.

Effect of reactor configuration on the subcritical water hydrolysis of recycled paper mill sludge

Recycled paper mill sludge (RPMS) was hydrothermally treated by subcritical water (SBW) in two modes of operation, namely semi-continuous and batch, at temperatures in the range 150–250°C, and 100bar. The performance of both systems was analyzed in terms of degree of hydrolysis, product yield and formation of degradation products. The highest degree of RMPS hydrolysis was achieved using the batch reactor configuration, while in the semi-continuous system higher yields of water soluble compounds (WSC) and monosaccharides were achieved. By using the semi-continuous system at 100bar, 250°C and a water flow rate of 5mL/min, 40% of the organic carbon content of RPMS was recovered in the form of soluble compounds. Additionally 20% of total carbohydrates and 75% of total lignin of RPMS were recovered as soluble material.Detailed mass balances performed for both operational modes revealed that under batch mode, the naturally occurring compounds found in RPMS underwent significant transformation, generating derivatives referred to as degradation products.An analysis of the severity factor was performed for both operational modes. It was concluded that significant values of WSC were only obtained for severity factors higher than four.

Preparation of hydrolytic liquid from dried distiller's grains with solubles and fumaric acid fermentation by Rhizopus arrhizus RH 7-13

Fumaric acid production from lignocellulosic materials is an alternative chemicals production system. This work investigated the suitable conditions for hydrolysis of dried distiller's grains with solubles (DDGS). The hydrolytic liquid was subsequently used for the production of fumaric acid. After optimizing the hydrolysis conditions, the most suitable concentration of H2SO4 (2%), hydrolysis temperature (120 °C), hydrolysis time (100min) and solid/liquid ratio (1:10) were obtained. The yield of monosaccharides reached 258 mg/g DDGS and 15.88 g/L glucose, 7.53 g/L xylose and 2.35 g/L arabinose were obtained in unprocessed hydrolytic liquid. The furfural inhibitor in the hydrolytic liquid was also detected and the yield of it was reducing progressively in the pretreatment process. The ferment ability of the hydrolytic liquid from DDGS was tested through the process of fumaric acid production by Rhizopus arrhizus RH 7-13. The unprocessed hydrolytic liquid was not appropriate for the fermentation process. The yield of fumaric acid from the concentrated processed hydrolytic liquid reached 18.93 g/L, which was close to the yield of fermenting 80 g/L glucose. This result indicated that the commonly used carbon resource glucose could to some extent be replaced by processed hydrolytic liquid.

Improvement of Acid Hydrolysis Procedures for the Composition Analysis of Herbaceous Biomass

The accurate characterization of biomass is critical for development of bioenergy feedstocks and their utilization. Most analytical approaches involve acid hydrolysis of the polysaccharides in biomass, leaving most of the lignin as insoluble residue. A limitation of this approach is that the same conditions used to hydrolyze polysaccharides also degrade the liberated monosaccharides. The NREL-compiled procedures account for this effect with “Sugar Recovery Standards”, in which a solution of the expected monosaccharides is prepared and subjected to the dilute-hydrolysis portion of the procedure; however, this tends to overestimate monosaccharide degradation and introduce bias between polysaccharides of different lability. The following recommended method modifications are intended to reduce these errors: (1) quantification of immediate degradation products of monosaccharides and their stoichiometric addition to the monosaccharide yield; (2) the adjustment of this combined yield with sugar recovery standards; and (3) preautoclave analysis of hydrolyzates to improve the estimation of monosaccharide concentration profiles for adjustment calculations.