Acid Pretreatment Hydrolysis Research Articles

Production of microalgal biochar and reducing sugar using wet torrefaction with microwave-assisted heating and acid hydrolysis pretreatment

This study employed the microwave-assisted acid hydrolysis pretreatment using wet torrefaction on two indigenous microalgae, Chlorella vulgaris ESP-31 and Chlorella sp. GD with different biomass composition to investigate the yields of solid biochar and total reducing sugar in the liquid hydrolysate. Operating conditions at low temperatures (160, 170 °C) with short holding time (5, 10 min) under several concentrations of diluted acid medium (0, 0.1 and 0.2 M) were carried out to investigate the torrefaction severity effects towards the properties of the solid and liquid products. The highest biochar yields of 54.5% and 74.6% are obtained from C. vulgaris ESP-31 and Chlorella sp. GD, respectively under the wet torrefaction conditions with an improvement in the properties for fuel and value-added environmental application. The highest total reducing sugar concentration of 98.11 g/L and 12.08 g/L are obtained in C. vulgaris ESP-31 and Chlorella sp. GD liquid hydrolysates, respectively after acid hydrolysis pretreatment. With the co-production of high total reducing sugar in the liquid hydrolysate that can be utilized for bioethanol production and solid biochar as another value-added product, the acid hydrolysis pretreatment using wet torrefaction can be one of the conversion technologies towards the application of renewable energy production.

Chemical and thermal analysis of lignin streams from Robinia pseudoacacia L. generated during organosolv and acid hydrolysis pre-treatments and subsequent enzymatic hydrolysis

Lignin streams produced in biorefineries are commonly used to obtain energy. In order to increase the competitiveness of this industry, new lignin valorization routes are necessary, for which a depth characterization of this biological macromolecule is essential. In this context, this study analyzed lignin streams of Robinia pseudoacacia L. generated during organosolv and acid hydrolysis pre-treatments and during the subsequent enzymatic hydrolysis. These lignins included dissolved lignins from pre-treatment liquors and saccharification lignins from pre-treated materials. Chemical composition and structural features were analyzed by analytical standard methods and Fourier Transform Infrared spectroscopy (FTIR), size exclusion chromatography (SEC), 13C solid state nuclear magnetic resonance (13C NMR) and 1H–13C two-dimensional nuclear magnetic resonance (2D NMR); while thermal characterization included thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). In general, all studied lignins contained a predominance of β-O-4′ aryl ether linkages, followed by resinol (β-β′) and phenylcoumaran (β-5′), with a predominance of syringyl over guaiacyl and hydroxyphenyl units. Nevertheless, the dissolved lignins revealed a removal of linkages, especially β-O-4′, leading to an enrichment of phenolic groups. Moreover, high thermal stability and good thermoplasticity were characteristics of these lignins. Contrary, the saccharification lignins exhibited a more intact structure, but with an important remaining carbohydrates content.

Hydrothermal Liquefaction and Photocatalytic Reforming of Pinewood (Pinus ponderosa)-Derived Acid Hydrolysis Residue for Hydrogen and Bio-oil Production

Pretreatment of lignocellulosic biomass (LCB) is a prerequisite for downstream bioconversion of its cellulosic components to second-generation biofuels. Acid hydrolysis pretreatment separates most of the hemicellulose and cellulose from lignin. However, the lignin-rich acid hydrolysis residue (AHR) may contain 20–50 wt % feedstock biomass. To improve the economics of LCB-based biorefinery, the AHR needs to be valorized. In this study, we have performed hydrothermal liquefaction (HTL) of AHR derived from the dilute acid treatment of pinewood for H₂ and bio-oil generation. A slurry of AHR at a biomass-to-water ratio of 1:30 was hydrothermally liquefied in the presence of a homogeneous Ni(NO₃)₂ catalyst at 250, 275, and 300 °C. About 16 wt % bio-oil and 51 mL of H₂ were generated at 300 °C and 60 min into the reaction. Based on elemental analysis, the higher heating value of bio-oil was found to be 29.8 MJ/kg. The aqueous coproduct generated during the HTL reaction was treated with activated carbon and subjected to the photocatalytic reforming (PR) process in the presence of a Pt/TiO₂ catalyst that produced an additional 90 mL of H₂ at NTP conditions. Preliminary calculations were performed to understand the energy recovery in terms of the products generated based on the total energy consumed for both HTL and PR processes.

Effect of Dual Modification on the Spectroscopic, Calorimetric, Viscosimetric and Morphological Characteristics of Corn Starch.

The effect of dual modification of corn starch, including hydrolysis and succinylation, were evaluated through peak viscosity (PV) analysis, differential scanning calorimetry (DSC), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. This dual modification was shown to increase the reaction efficiency (RE) and degree substitution (DS) compared with starches that were not subjected to acid hydrolysis pretreatment with a 44% and 45% increase respectively. After acid hydrolysis pretreatment, the surface of the corn starch granules exhibited exo-erosion and whitish points due to the accumulation of succinyl groups. The peak viscosity was reduced significantly with the acid hydrolysis pretreatment (between 3 and 3.5-fold decrease), which decreased the pasting temperature and peak time to 20 °C and 100 s respectively. In addition, the dual modification of corn starch altered certain thermal properties, including a reduction in the enthalpy of gelatinization (ΔH) and a higher range of gelatinization (around 6 °C), which may effectively improve industrial applications. Modifications on the FTIR spectra indicated that the dual modification affected the starch crystallinity, while the Raman spectra revealed that the dual modification disrupted the short-range molecular order in the starch. Rearrangement and molecular destabilization of the starch components promoted their granular amphiphilic properties.

Detoxification of Hydrolysates of the Red Seaweed Gelidium amansii for Improved Bioethanol Production

In this study, bioethanol was produced from the seaweed Gelidium amansii as biomass through separate hydrolysis and fermentation (SHF) processes. The SHF processes examined in this study include thermal acid hydrolysis pretreatment, enzymatic saccharification, detoxification, and fermentation. Thermal acid hydrolysis pretreatment was conducted using H2SO4, with a slurry content of 8-16% and treatment time of 15-75min. The optimal conditions for thermal acid hydrolysis pretreatment were 12% (w/v) seaweed slurry content and 180mM H2SO4 at 121°C for 45min, at which 26.1g/L galactose and 6.8g/L glucose were produced. A monosaccharide (mainly glucose) was also obtained from the enzymatic saccharification of thermal acid hydrolysate using 16U/mL Celluclast 1.5L enzyme at 45°C for 36h. Detoxification was performed using the adsorption method with activated carbon, the overliming method with Ca (OH)2, and the ion exchange method with polyethyleneimine. Among those detoxification methods, activated carbon showed the best performance for hydroxymethylfurfural removal. Ethanol fermentation was performed using 12% (w/v) seaweed hydrolysate with Saccharomyces cerevisiae adapted to galactose as well as various detoxification treatments.

Biorefinery of Lignocellulosic Biomass from an Elm Clone: Production of Fermentable Sugars and Lignin‐Derived Biochar for Energy and Environmental Applications

AbstractValorization of lignocellulosic feedstock from a Dutch elm disease tolerant Ulmus minor clone was studied as a new biomass resource. Herein, fermentable sugars and activated carbons from the side‐stream lignins were produced. For the sugar extraction organosolv and acid hydrolysis pretreatments prior to enzymatic hydrolysis were compared for the first time for this clone prior to enzymatic hydrolysis; organosolv was more efficient for delignification (49 %), while acid hydrolysis was more efficient at eliminating hemicelluloses (95 %). A high final glucose concentration of 22–23.5 g L−1 was obtained after enzymatic hydrolysis suggesting that this clone can be considered a potential source for glucose‐based biofuel production. The side‐stream lignins were converted to microporous biochars of high surface area (1220 m2 g−1) and micropore volume (0.42 cm3 g−1). These biochars exhibited excellent properties as electrodes in supercapacitors with a specific capacitance of 118 F g−1 and a high energy density of 14 Wh kg−1 at 7000 W kg−1, while they were also efficient adsorbents in water remediation of model contaminants.

A two stage pretreatment process to maximise recovery of sugars from cotton gin trash

We evaluated a two stage pretreatment process for liberation of sugars from cotton gin trash (CGT) for ethanol production. The 1st stage releases C5 sugars for propagation of yeast inoculum intended for C6 sugar fermentations. The effects of a range of dilute acid hydrolysis pretreatment conditions on CGT were assessed. Propagation of recombinant Saccharomyces cerevisiae GSF335 in 1st stage liquors yielded up to 66 g yeast biomass kg−1 CGT. In the presence of PEG 6000, 2nd stage pretreated fibres were highly acquiescent to enzyme hydrolysis, yielding up to 242 g glucose kg−1 CGT. We conclude that the optimum conditions for recovery of sugars from CGT are: 1:6 solids to liquids ratio with 12% H2SO4 wt. on solids at 180 °C for 15 min during the 1st stage, with the ensuing pressed unwashed fibre heated to 200 °C for 5 min during the 2nd stage.

Conversion of Potato Starch and Peel Waste to High Value Nanocrystals

The present study aimed to convert starch and potato peel waste to nanocrystals. Starch nanocrystals were prepared using two methodologies: direct acid hydrolysis and enzyme pretreatment followed by acid hydrolysis. Direct hydrolysis broke down the starch granules to nanocrystals in 12 days. Enzyme pretreatment with starch hydrolytic enzymes (α-amylase and amyloglucosidase) reduced the time for preparation of starch nanocrystals by 6 days. Starch nanocrystals of optimum size were obtained with both the treatments and the resultant size ranged from 10 to 50 nm. Nanocrystals were disk-like platelets in appearance. Cellulose nanocrystals were derived from cellulosic material in the potato peel. Cellulose was isolated from peel waste with alkali treatment. Further, cellulose nanocrystals from potato peel and cellulose microcrystalline were prepared by acid hydrolysis. Microscopic images revealed that the aqueous suspension of cellulose nanocrystals derived from potato peel were single rod shaped, whereas those derived from cellulose microcrystalline were rod-like nanoparticles, agglomerated in the form of bundles including some of the rods in single units (well separated). The size of potato peel nanocrystals ranged from 40 to 100 nm (length) and cellulose microcrystalline ranged from 4 to 20 nm (diameter) by 110 to 250, given 4 to 20 nm (length), respectively. As starch nanocrystals as well as cellulose nanocrystals are derived from biopolymer, both can be considered safe for humans and the environment. Moreover, the biodegradable nature of these nanocrystals makes them superior over metallic nanoparticles, particularly in the field of nanocomposites.

The Isolation of Nanofibre Cellulose from Oil Palm Empty Fruit Bunch Via Steam Explosion and Hydrolysis with HCl 10%

Cellulose nanofibrils were obtained from oil palm empty fruit bunch using steam explosion and hydrolized with 10% solution of HCl. Steam explosion coupled with acid hydrolysis pretreatment on the oil palm empty fruit bunch was very effective in the depolymerization and defibrillation process of the fibre to produce fibers in nanodimension. Structural analysis of steam exploded fibers was determined by Fourier Transform Infrared (FT-IR) spectroscopy. Thermal stability of cellulose measured using image analysis software image J. Characterization of the fibers by TEM and SEM displayed that fiber diameter decreases with mechanical-chemical treatment and final nanofibril size was 20-30 nm. FT-IR and TGA data confirmed the removal of hemicellulose and lignin during the chemical treatment process.

A two-step bioprocessing strategy in pentonic acids production from lignocellulosic pre-hydrolysate.

Efficient utilization (over needless disposal) of biorefinery pre-hydrolysate is an economically relevant practice for improving biorefinery financial prospects. The liquid fraction obtained after acid hydrolysis pretreatment of lignocellulosic biomass, called pre-hydrolysate, are predominantly comprised of hemicellulosic carbohydrates. Using a two-step bioprocess, the hexoses were selectively fermented to ethanol by S. cerevisiae to clear the path for Gluconobacter oxydans transformation of pentoses to a high purity pentonic acids solution. Finally, approximately 180g pentonic acids and 19g ethanol could be produced starting from pre-hydrolysate produced from 1kg corn stover. The results demonstrate execution of our objective to prove this bioconversion method for producing high purity pentonic acids starting from crude lignocellulosic pre-hydrolysate, a wastefully disregarded biorefinery process stream.

Study of the Ultrastructure of Eucalyptus globulus Wood Substrates Subjected to Auto-Hydrolysis and Diluted Acid Hydrolysis Pre-treatments and Its Influence on Enzymatic Hydrolysis

Dilute acid hydrolysis (DAH) and auto-hydrolysis (AU) have demonstrated to be optimal pre-treatments for the generation of biofuels from wood. Recent studies have highlighted the importance of ensuring the accessibility of cellulose enzymes during the enzymatic hydrolysis (EH) of pre-treated materials. In this work, the microscopic and nanoscopic structures of Eucalyptus globulus samples pre-treated by AU and DAH were evaluated by different techniques to understand the effect of the ultrastructure of samples on the enzymatic conversion and cellulose accessibility for bioethanol production. Microscopic techniques revealed changes in the physical characteristics of pre-treated fibers, coalescence at microscopic level, and differences in the chemical distribution of lignocellulosic components depending on the severity and type of pre-treatment. The atomic force microscopy-based nanoscopic study of samples showed differences in the effect of the pre-treatments on the ultrastructure of samples, with DAH pre-treatment producing major changes in the secondary cell wall with respect to AU samples at comparable severities, and a positive effect of the DAH ultrastructure changes to increase the EH yield.

Mesophilic continuous fermentative hydrogen production from acid pretreated de-oiled jatropha waste hydrolysate using immobilized microorganisms

Mesophilic hydrogen production from acid pretreated hydrolysate (biomass concentration of 100g/L and 2% hydrochloric acid) of de-oiled jatropha waste was carried out in continuous system using immobilized microorganisms at various hydraulic retention times (HRTs) ranging from 48 to 12h. The experimental results of the reusability of immobilized microorganisms showed their stability up to 10 cycles with an average cumulative hydrogen production of 770mL/L. The peak hydrogen production rate and hydrogen yield were 0.9L/L*d and 86mL/greducing sugars added, respectively at 16h HRT, with butyrate as the predominant volatile fatty acid. The microbial community analysis revealed that majority of the PCR-DGGE bands were assigned to genus Clostridium and were perhaps the key drivers of the higher hydrogen production.

Impact of amylosucrase modification on the structural and physicochemical properties of native and acid-thinned waxy corn starch.

Recombinant amylosucrase from Neisseria polysaccharea was utilized to modify native and acid-thinned starches. The molecular structures and physicochemical properties of modified starches were investigated. Acid-thinned starch displayed much lower viscosity after gelatinization than did the native starch. However, the enzyme exhibited similar catalytic efficiency for both forms of starch. The modified starches had higher proportions of long (DP>33) and intermediate chains (DP 13-33), and X-ray diffraction showed a B-type crystalline structure for all modified starches. With increasing reaction time, the relative crystallinity and endothermic enthalpy of the modified starches gradually decreased, whereas the melting peak temperatures and resistant starch contents increased. Slight differences were observed in thermal parameters, relative crystallinity, and branch chain length distribution between the modified native and acid-thinned starches. Moreover, the digestibility of the modified starches was not affected by acid hydrolysis pretreatment, but was affected by the percentage of intermediate and long chains.

Preparation and characterization of functional cellulose nanofibrils via formic acid hydrolysis pretreatment and the followed high-pressure homogenization

This article described a sustainable route, which combined relatively mild formic acid (FA) hydrolysis pretreatment of bleached softwood pulp with high-pressure homogenization, to prepare cellulose nanofibrils (F-CNFs). Results showed that the prepared F-CNFs had high thermal stability (e.g. the onset decomposition temperature was over 290°C). Also, it was found that the prepared F-CNFs were more homogeneous and the length of the F-CNFs became shorter with the increase of hydrolysis time in FA hydrolysis, and a maximum crystallinity index of about 52.9% could be achieved when the hydrolysis time was 6h. Compared to H-CNFs (prepared by HCl pretreatment), F-CNFs showed better dispersibility in DMSO, DMF and DMAC respectively because of the introduction of ester groups on the surface of F-CNFs. This high compatibility leads to that the F-CNFs may have great potential in reinforcing polymeric matrix materials. In addition, FA could be easily recovered. Thus, FA hydrolysis pretreatment plus high-pressure homogenization could be a sustainable and economically feasible process for the production of CNFs.

Typical conversion of lignocellulosic biomass into reducing sugars using dilute acid hydrolysis and alkaline pretreatment

The development and production of fossil fuel alternatives have become one of the main focal points in recent investigations. Lignocellulosic biomass is a renewable source of fermentable sugars for second-generation biofuels and chemicals via biotechnological pathways. However, the presence of lignin and hemicellulose in lignocellulosic biomass makes it difficult for the biomass to be hydrolyzed or digested during fermentation. Thus, effective biomass pretreatment is vital. The present review shows that chemical pretreatment is the current preferred method to obtain high sugar yields at low cost, with dilute acid and alkaline hydrolysis as the two most reported technologies. Dilute acid favours hydrolysis of the hemicelluloses whereas alkaline hydrolysis targets the lignin fraction. Both methods have merits and demerits, and have been combined with other treatments such as hydrothermal and enzymatic hydrolysis. Further investigation is required to improve the pretreatment processes and to ensure the economic viability of bioconversion.

Bioethanol production from detoxified hydrolysate and the characterization of oxalic acid pretreated Eucalyptus (Eucalyptus globulus) biomass

In this study, different detoxification treatments (XAD-4 resin adsorption [XAD] and electrodialysis) on oxalic acid pretreated hydrolysate were evaluated. Two different detoxification processes were applied to remove fermentation inhibitors from the oxalic acid pretreated hydrolysate of eucalyptus. The hydrolysates contain sugars (glucose, xylose, and arabinose) and inhibitors. Acetic acid was the main inhibitor in the original hydrolysate, and more total phenolic compounds were generated than hydroxymethyl furfural and furfural. The acetic acid was removed 100% by the electrodialysis process, and total phenolic compounds and furfural were effectively removed from the hydrolysate by XAD. Based on the process order, the combined electrodialysis-XAD process was more effective for ethanol fermentation compared to the combined XAD-electrodialysis process. Ethanol fermentation was successfully performed using the electrodialysis-XAD-treated hydrolysate and achieved a production of 7.83g/L of ethanol, corresponding to an ethanol yield of 0.40g/g within 48h. Fourier transform infrared, X-ray diffractometer, and scanning electron microscopy were used to investigate the characteristics of the raw material and pretreated biomass. The results showed that most of the hemicellulose was degraded during oxalic acid pretreatment. Therefore, the crystallinity value increased from 49.79% to 56.93%. The surface of the raw material was smooth, plump, and compact, whereas the pretreated biomass was more fragmented.

Batch and continuous biogenic hydrogen fermentation of acid pretreated de-oiled jatropha waste (DJW) hydrolysate

In an attempt to tailor the efficient hydrogen fermentation from hydrochloric acid-pretreated hydrolysate of de-oiled jatropha waste (DJW), batch tests were conducted to find the optimal hydrolysate concentration, temperature and pH.

Preparation of highly charged cellulose nanofibrils using high-pressure homogenization coupled with strong acid hydrolysis pretreatments

Cellulose nanofibrils (CNFs) are attracting much attention for the advantages of excellent mechanical strength, good optical transparency, and high surface area. An eco-friendly and energy-saving method was created in this work to produce highly negative charged CNFs using high-pressure mechanical defibrillation coupled with strong acid hydrolysis pretreatments. The morphological development, zeta potential, crystal structure, chemical composition and thermal degradation behavior of the resultant materials were evaluated by transmission electron microscopy (TEM), zeta potential analysis, X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR), and thermogravimetric analysis (TGA). These CNFs were fully separated, surface-charged, and highly entangled. They showed a large fiber aspect ratio compared to traditional cellulose nanocrystrals that are produced by strong acid hydrolysis. Compared to hydrochloric acid hydrolysis, the CNFs produced by sulfuric acid pretreatments were completely defibrillated and presented stable suspensions (or gels) even at low fiber content. On the other hand, CNFs pretreated by hydrochloric acid hydrolysis trended to aggregate because of the absence of surface charge. The crystallinity index (CI) of CNFs decreased because of mechanical defibrillation, and then increased dramatically with increased sulfuric acid concentration and reaction time. FTIR analysis showed that the COSO3 group was introduced on the surfaces of CNFs during sulfuric acid hydrolysis. These sulfate groups accelerated the thermal degradation of CNFs, which occurred at lower temperature than wood pulp, indicating that the thermal stability of sulfuric acid hydrolyzed CNFs was decreased. The temperature of the maximum decomposition rate (Tmax) and the maximum weight-loss rates (MWLRmax) were much lower than for wood pulp because of the retardant effect of sulfuric acid during the combustion of CNFs. By contrast, the CNFs treated with hydrochloric acid had better thermal stability, because no functional groups were introduced on the surface.

Production and storage of biohydrogen during sequential batch fermentation of Spirogyra hydrolyzate by Clostridium butyricum

The biological hydrogen production from Spirogyra sp. biomass was studied in a SBR (sequential batch reactor) equipped with a biogas collecting and storage system. Two acid hydrolysis pre-treatments (1N and 2N H2SO4) were applied to the Spirogyra biomass and the subsequent fermentation by Clostridium butyricum DSM 10702 was compared. The 1N and 2N hydrolyzates contained 37.2 and 40.8 g/L of total sugars, respectively, and small amounts of furfural and HMF (hydroxymethylfurfural). These compounds did not inhibit the hydrogen production from crude Spirogyra hydrolyzates. The fermentation was scaled up to a batch operated bioreactor coupled with a collecting system that enabled the subsequent characterization and storage of the biogas produced. The cumulative hydrogen production was similar for both 1N and 2N hydrolyzate, but the hydrogen production rates were 438 and 288 mL/L.h, respectively, suggesting that the 1N hydrolyzate was more suitable for sequential batch fermentation. The SBR with 1N hydrolyzate was operated continuously for 13.5 h in three consecutive batches and the overall hydrogen production rate and yield reached 324 mL/L.h and 2.59 mol/mol, respectively. This corresponds to a potential daily production of 10.4 L H2/L Spirogyra hydrolyzate, demonstrating the excellent capability of C. butyricum to produce hydrogen from microalgal biomass.

Thermal Acid Hydrolysis Pretreatment, Enzymatic Saccharification and Ethanol Fermentation from Red Seaweed, Gracilaria verrucosa

In this study, the red seaweed Gracilaria verrucosa was used as a bioethanol producing biomass. G. verrocosa has a high content of easily degradable carbohydrates, making it a potential substrate for the production of liquid fuels [8]. The carbohydrates in G. verrucosa can be categorised according to their chemical structures: alginate, carrageenan, and agar. Carrageenan and agar, which are plentiful in the seaweed, can be used as a source of galactose and glucose. Various pretreatment techniques have been introduced to enhance the overall hydrolysis yield, and can be categorized into physical, chemical, biological, enzymatic or a combination of these [1]. Dilute acid hydrolysis is commonly used to prepare seaweed hydrolysates for enzymatic saccharification and fermentation for economic reasons [13]. However, thermal acid hydrolysis pretreatment for 3,6anhydrogalactose from G. verrucosa have produced 5hydroxymethylfurfural (HMF), an inhibitory compound for ethanol production [8]. One of the problems encountered in G. verrucosa fermentation has been high concentrations of NaCl due to its origin from sea water [3]. High-salt stress to yeasts is a significant impediment on the production of ethanol from seaweed hydrolysates. Salt stress in yeasts results in two phenomena: ion toxicity and osmotic stress [11]. Defense responses to salt stress are based on osmotic adjustments by osmolyte synthesis and cation transport systems for sodium exclusion [20]. The preferential utilization of glucose over non-glucose sugars by yeast often results in low overall ethanol production and yield. When yeast grows on a mixture of glucose and galactose, the glucose is metabolized first, whereas The seaweed, Gracilaria verrucosa, was fermented to produce bioethanol. Optimal pretreatment conditions were determined to be 12% (w/v) seaweed slurry and 270 mM sulfuric acid at 121C for 60 min. After thermal acid hydrolysis, enzymatic saccharification was carried out with 16 U/ml of mixed enzymes using Viscozyme L and Celluclast 1.5 L to G. verrucosa hydrolysates. A total monosaccharide concentration of 50.4 g/l, representing 84.2% conversion of 60 g/l total carbohydrate from 120 g dw/l G. verrucosa slurry was obtained by thermal acid hydrolysis and enzymatic saccharification. G. verrucosa hydrolysate was used as the substrate for ethanol production by separate hydrolysis and fermentation (SHF). Ethanol production by Candida lusitaniae ATCC 42720 acclimated to high-galactose concentrations was 22.0 g/l with ethanol yield (YEtOH) of 0.43. Acclimated yeast to high concentrations of specific sugar could utilize mixed sugars, resulting in higher ethanol yields in the seaweed hydrolysates medium.