Bioethanol Concentration Research Articles

Kinetic modeling of batch bioethanol production from CCN-51 Cocoa Mucilage

• Bioethanol by fermentation of CCN-51 cocoa mucilage with Saccharomyces cerevisiae • Experiments performed in batch bioreactor varying temperature, pH and yeast concentration • Logistic, Modified Gompertz and Andrews and Levenspiel models checked for describing kinetics • Andrews and Levenspiel model better fits experimental results The aim of this study was the production of bioethanol generated during the fermentation of CCN-51 Cocoa mucilage with Saccharomyces cerevisiae yeast and the fitting of experimental data to the mathematical models: Logistic, modified Gompertz, and Andrews and Levenspiel. There are limited studies regarding the high energy potential of cocoa mucilage from Ecuador for bioethanol production as a gasoline additive. Currently, this by-product of the cocoa industry is considered as waste. Discontinuous fermentation was performed in a batch bioreactor under different conditions of pH, temperature and yeast concentration. During the reaction, bioethanol concentration, yeast and consumed substrate were evaluated by means of microdiffusion, dry weight by lyophilization and UV spectrophotometry, respectively. The result of the final bioethanol concentration was 25.41 g/L at a temperature of 35 °C, pH of 4 and yeast concentration of 3 g/L. The models were fitted with determination coefficients greater than 0.9. From the results, the logistic model was used to describe yeast growth. Modified Gompertz model is considered appropriate for modeling bioethanol production. Both models fit the data adequately; however, Andrews and Levenspiel model, besides of the good adjustment, considered inhibition terms of the substrate and product.

Advancement of fermentable sugars from fresh elephant ear plant weed for efficient bioethanol production.

Bioethanol is considered one of the most promising next-generation automotive fuels, as it is carbon neutral and can be produced from renewable resources, like lignocellulosic materials. The present research investigation aimed to utilize the elephant ear plant, a hazardous plant (weed) also considered an invasive species, as a font of non-edible lignocellulosic biomass for bioethanol production. The freshly collected elephant ear plant (leaves and stalk) was chopped into small pieces (1–2 cm) and then homogenized to a paste using a mechanical grinder. The sample pretreatment was done by flying ash for three different time durations (T1 = 0 min, T2 = 15 min, and T3 = 30 min) with 3 replications. All treatment samples were measured for total sugar and reducing sugar content. The concentration of reducing sugar archived was T1 = 0.771 ± 0.1 mg/mL, T2 = 0.907 ± 0.032 mg/mL, and T3 = 0.895 ± 0.039 mg/mL, respectively. The results revealed that the chemical composition was different among treatments. The hydrolysis was performed using cellulase enzymes at 35 °C for the hydrolysis process. The hydrolysate was inoculated with 1% of S. cerevisiae and maintained at room temperature without oxygen for 120 h. Bioethanol concentration was measured by using an ebulliometer. The efficient ethanol percentage was 1.052 ± 0.03 mg/mL achieved after the fermentation. Therefore, the elephant ear plant invasive weed could be an efficient feedstock plant for future bioethanol production.

Bioconversion and valorization of cassava-based industrial wastes to bioethanol gel and its potential application as a clean cooking fuel

Bioethanol gel is gaining more attention for clean cooking fuel as green technology and partial replacement of burning the biomass for cooking purposes. The conversion of tapioca flour wastes to bioethanol and its production to bioethanol gel have not been performed. Tapioca flour industrial wastes are rich in sugar, and promising for the low-cost biomass for bioethanol production. The production of bioethanol from cassava peels and cassava pomace ( onggok ) and its bioethanol gel formulation were performed in this study. The research was carried out by treating tapioca starch wastes with pretreatment and hydrolysis, continued by applying eight fermentation treatments, and the bioethanol yields were analyzed quantitatively. Then, the bioethanol gel was formulated. The viscosity, calorific value, burning time, flame color, and ash content of the bioethanol gel were analyzed. It can be concluded that cassava-based industrial wastes were successfully converted to bioethanol with a 35% yield resulting in a 25% bioethanol concentration at a 2.64 g/L per h conversion rate. The efficiency of bioconversion was 86%, and reflux column distillation could increase the bioethanol concentration to 92%. Carboxymethyl cellulose (CMC) was an effective gelling agent and improved the viscosity at 1.338 mPa.s and burning time to 184 min. The ash content of all samples was lower than 5%, meaning that it is promising for further application as a household cookstove fuel. • Cassava peels and onggok bioconversion to bioethanol was successfully done. • The reflux column distillation increased the bioethanol concentration up to 92%. • CMC was a perfect gelling agent for bioethanol gel formulation. • The bioethanol gel (burning time 184 min and ash <5%) is promising for household biofuel.

Bioethanol Production from Cellulose-Rich Corncob Residue by the Thermotolerant Saccharomyces cerevisiae TC-5.

This study aimed to select thermotolerant yeast for bioethanol production from cellulose-rich corncob (CRC) residue. An effective yeast strain was identified as Saccharomyces cerevisiae TC-5. Bioethanol production from CRC residue via separate hydrolysis and fermentation (SHF), simultaneous saccharification and fermentation (SSF), and prehydrolysis-SSF (pre-SSF) using this strain were examined at 35–42 °C compared with the use of commercial S. cerevisiae. Temperatures up to 40 °C did not affect ethanol production by TC-5. The ethanol concentration obtained via the commercial S. cerevisiae decreased with increasing temperatures. The highest bioethanol concentrations obtained via SHF, SSF, and pre-SSF at 35–40 °C of strain TC-5 were not significantly different (20.13–21.64 g/L). The SSF process, with the highest ethanol productivity (0.291 g/L/h), was chosen to study the effect of solid loading at 40 °C. A CRC level of 12.5% (w/v) via fed-batch SSF resulted in the highest ethanol concentrations of 38.23 g/L. Thereafter, bioethanol production via fed-batch SSF with 12.5% (w/v) CRC was performed in 5-L bioreactor. The maximum ethanol concentration and ethanol productivity values were 31.96 g/L and 0.222 g/L/h, respectively. The thermotolerant S. cerevisiae TC-5 is promising yeast for bioethanol production under elevated temperatures via SSF and the use of second-generation substrates.

Bioethanol extraction from Coconut (Cocos nucifera Linnaeus) embryo using Saccharomyces cerevisiae

The world oil crisis is looming as supply levels are under threat. This study is the first attempt to extract bioethanol from Coconut (Cocos nucifera Linnaeus) embryo using Saccharomyces cerevisiae. Samples of coconut embryos were collected, ground, and subjected to acid hydrolysis. These were then filtered, and the residues collected were treated with two different amounts of buffer solution. Cultured strains of S. cerevisiae were inoculated into the prepared Yeast Extract-Peptone-Dextrose (YPD) broth. Buffer-treated samples were then inoculated with 5 ml of the yeast solution and allowed to ferment at various times. After different fermentation times, samples were filtered, and the obtained filtrates were subjected to the distillation process for bioethanol concentration determination. Results showed that samples allowed to ferment at 72 h and 96 h yielded 7.11% and 12.22% bioethanol, respectively. The samples treated with 50 ml and 100 ml of buffer solution produced 9.02% and 10.31% bioethanol, respectively. The main effect of fermentation time on bioethanol concentration was statistically substantial such that samples allowed to ferment in 96 h yielded higher bioethanol concentration than samples permitted to ferment in 72 h. Based on the results, bioethanol could be extracted from a novel, cheap, and readily available coconut embryo using S. cerevisiae.

A comparative study on bioethanol production from rice straw and banana pseudostem through simultaneous saccharification and fermentation using Kluyveromyces marxianus

To improve the efficiency of second-generation bioethanol production, simultaneous Saccharification and Fermentation (SSF) of top agricultural wastes in the Philippines such as rice straw and banana pseudostem was conducted using commercial enzymes and the thermotolerant yeast Kluyveromyces marxianus. Residues were initially subjected to chemical treatment prior to SSF. A constant inoculum loading of 10% vv -1 was introduced during SSF, and mixed with a nutrient supplemented solution. Aside from the enzyme loading, the effect of reaction temperature and reaction time on ethanol concentration was assessed. Among the tested parameters, only reaction time had a significant effect on the bioethanol concentration from both biomasses. For a pre-treated rice straw with 70.93% ww -1 holocellulose, highest ethanol concentration obtained was 6.30+0.44 gL -1 at 45°C, reaction time of 48 h and with enzyme loading of 30 FPUg -1. On the other hand, 5.35+0.29 gL -1 ethanol was achieved from SSF of banana pseudostem with 67.75% ww -1 holocellulose, also at 35°C, at a lower reaction time of 24 h and same enzyme loading of 30 FPUg -1. This study also proves that the thermotolerant K. marxianus was capable of producing bioethanol from lignocellulosics through SSF, thereby considering it as a potential alternative to Saccharomyces cerevisiae for bioethanol production.

Production of Cellulase and bioethanol by ethanol-tolerant coculture of Bacillus cereus and Fusarium solani

Cellulase is an enzyme produced by fungi and bacteria that hydrolyzes cellulose by breaking down the glycosidic bond, β-1,4 that binds sugar glucose units. Bioethanol and cellulase enzyme were produced by ethanol-tolerant of Bacillus cereus co-culture. So the production of filamentous solani were using the wastes of Cynodon dactylon L. The highest activity of enzyme was at 96 hour/30°C of incubation. The optimal pH value was 7.5, while the carbon concentration was 3%. On the other hand, the best inoculum ratio was 0.5/100 mL (52 × 108 cell/mL bacterial cells and 105 conidia/mL of the fungus). In order to test the efficiency of ethanol production by the co-culture by using different concentrations of pure ethanol was measured in the solid medium. Both Bacillus sp. and F. solani tolerated incubation with 5% ethanol. The best treatment when using 0.5% sulfuric acid which gave the best concentration of reduced sugars and the results showed a difference in the concentration of sugars produced by the fermentation process, it was 3.9 mg/mL in the first day, whereas it was 2.51 mg/mL after 120 hours of fermentation, the concentration of bioethanol produced after fermentation was 195 g/L. In conclusion Cynodon dactylon L. wastes were treated by sulfuric acid, cellulase digestion, and autoclave treatment to be a good source of reducing sugars.

Valorization of sorghum distillery residue to produce bioethanol for pollution mitigation and circular economy

This research aims to study the wet torrefaction (WT) and saccharification of sorghum distillery residue (SDR) towards hydrochar and bioethanol production. The experiments are designed by Box-Behnken design from response surface methodology where the operating conditions include sulfuric acid concentration (0, 0.01, and 0.02 M), amyloglucosidase concentration (36, 51, and 66 IU), and saccharification time (120, 180, and 240 min). Compared to conventional dry torrefaction, the hydrochar yield is between 13.24 and 14.73%, which is much lower than dry torrefaction biochar (yield >50%). The calorific value of the raw SDR is 17.15 MJ/kg, which is significantly enhanced to 22.36–23.37 MJ/kg after WT. When the sulfuric acid concentration increases from 0 to 0.02 M, the glucose concentration in the product increases from 5.59 g/L to 13.05 g/L. The prediction of analysis of variance suggests that the best combination to maximum glucose production is 0.02 M H2SO4, 66 IU enzyme concentration, and 120 min saccharification time, and the glucose concentration is 30.85 g/L. The maximum bioethanol concentration of 19.21 g/L is obtained, which is higher than those from wheat straw (18.1 g/L) and sweet sorghum residue (16.2 g/L). A large amount of SDR is generated in the kaoliang liquor production process, which may cause environmental problems if it is not appropriately treated. This study fulfills SDR valorization for hydrochar and bioenergy to lower environmental pollution and even achieve a circular economy.

Valorisation of watermelon (Citrullus lanatus) rind waste into bioethanol: an optimization and kinetic studies

Bioethanol from renewable resources has gained great attention as one of the alternatives to partially replace transportation fuel from fossil fuel. Watermelon rind waste (WRW) is among of the renewable resources generated from agriculture industry that content high level of cellulose fraction which can be converted into bioethanol. To operate the fermentation process effective and efficiently, the fermentation is needed to be carried out under optimum condition. Furthermore, understanding the bioethanol production and growth kinetic model are necessary to predict the production of bioethanol under the optimized condition. Thus, this work was design to investigate the influence of fermentation operating parameters such as initial biomass concentration, rate of agitation and temperature towards bioethanol production. Further, the kinetic model for yeast growth during WRW hydrolysate fermentation was determined using logistic and Gompertz models. The maximum bioethanol concentration of 29.59 ± 2.52 gL−1 corresponding to bioethanol yield of 0.48 gbioethanol/gsugar was obtained when fermentation was performed using 150 gL−1 biomass at 150 rpm and 35 °C. Unstructured logistic model described well the growth of Saccharomyces cerevisiae during the ethanol production from WRW hydrolysate with maximum biomass concentration (Xmax), and growth rate (umax) is 2.92 gL−1 and 0.27 h−1. High significant R2 and low residual mean standard deviation (RMSD) value of 0.92 and 2.74 were obtained from this analysis. Furthermore, the product kinetic analysis using Luedeking–Piret analysis study adequately described bioethanol production from WRW hydrolysate as mixed-growth associate product formation manner (R2 = 0.92). The result obtained from this study provides a useful information on further bioprocessing system for bioethanol production from watermelon waste.

Experimental and Artificial Intelligence Modelling Study of Oil Palm Trunk Sap Fermentation

Five major operations for the conversion of lignocellulosic biomasses into bioethanol are pre-treatment, detoxification, hydrolysis, fermentation, and distillation. The fermentation process is a significant biological step to transform lignocellulose into biofuel. The interactions of biochemical networks and their uncertainty and nonlinearity that occur during fermentation processes are major problems for experts developing accurate bioprocess models. In this study, mechanical processing and pre-treatment on the palm trunk were done before fermentation. Analysis was performed on the fresh palm sap and the fermented sap to determine the composition. The analysis for total sugar content was done using high-performance liquid chromatography (HPLC) and the percentage of alcohols by volume was determined using gas chromatography (GC). A model was also developed for the fermentation process based on the Adaptive-Network-Fuzzy Inference System (ANFIS) combined with particle swarm optimization (PSO) to predict bioethanol production in biomass fermentation of oil palm trunk sap. The model was used to find the best experimental conditions to achieve the maximum bioethanol concentration. Graphical sensitivity analysis techniques were also used to identify the most effective parameters in the bioethanol process.

Utilization of solid tapioca waste for bioethanol production by co-fermentation of baker’s and tapai yeast

Tapioca processing from cassava produces abundant solid wastes. If left untreated, it potentially increases greenhouse gas emissions from the decomposition of organic matter. These gas emissions are known to accelerate global climate change. Tapioca solid waste (TSW) has high starch and cellulose content, making energy recovery possible through conversion to bioethanol. This research aimed to produce bioethanol from TSW by a co-fermentation method of baker’s and local tapai yeast. The research was conducted through multi-stages of enzymatic hydrolysis, followed by fermentation, then distillation. The hydrolysis produces hydrolyzate with a relatively high reducing sugar concentration. The ethanol fermentation results were optimally achieved in 48 h, namely substrate fermented by tapai yeast first for 24 h, followed by the addition of baker’s yeast and fermentation time to 48 h. This proces produced the highest yield and bioethanol concentration, almost 2 times higher than fermentation using baker’s or tapai yeast only. This results suggested that TSW can be used for bioethanol production by co-fermentation of baker’s and tapai yeast method. TSW usage will reduce global warming, bioethanol production can be widely applied in various fields replacing fossil fuel, thus has the potential to reduce global warming and global climate change.

Production of bio-ethanol by consecutive hydrogenolysis of corn-stalk cellulose

Current bio-ethanol production entails the enzymatic depolymerization of cellulose, but this process shows low efficiency and poor economy. In this work, we developed a consecutive aqueous hydrogenolysis process for the conversion of corn-stalk cellulose to produce a relatively high concentration of bio-ethanol (6.1 wt%) without humin formation. A high yield of cellulose (ca. 50 wt%) is extracted from corn stalk using a green solvent (80 wt% 1,4-butanediol) without destroying the structure of the lignin. The first hydrothermal hydrogenolysis step uses a Ni–WOx/SiO2 catalyst to convert the high cumulative concentration of cellulose (30 wt%) into a polyol mixture with a 56.5 C% yield of ethylene glycol (EG). The original polyol mixture is then subjected to subsequent selective aqueous-phase hydrogenolysis of the C–O bond to produce bioethanol (75% conversion, 84 C% selectivity) over the modified hydrothermally stable Cu catalysts. The added Ni component favors the good dispersion of Cu nanoparticles, and the incorporated Au3+ helps to stabilize the active Cu0-Cu+ species. This multi-functional catalytic process provides an economically competitive route for the production of cellulosic ethanol from raw lignocellulose.

Structural and composition modification of Harum Manis mango (Mangifera indica) leaves via chemical pretreatment for bioethanol production

Harum Manis mango leaves are considered lignocellulosic (LC) biomass that could contribute to the production of second generation (2G) bioethanol. However, pretreatment should be conducted to overcome the recalcitrance of LC biomass prior to bioethanol production. Hence, this study aims to elucidate the structural changes of the biomass of Harum Manis mango leaves after single-stage and two-stage chemical pretreatment. The Harum Manis mango leaves were treated with only acid, only alkaline, acid-alkaline, or alkaline-acid process. One per cent (v/v) sulphuric acid and 1% (w/v) sodium hydroxide were used as the acid and alkaline hydrolysing agent in the four approaches of pretreatment, respectively. Consequently, the pretreated biomass was enzymatically hydrolysed to produce reducing sugar followed by the conversion into bioethanol through yeast fermentation. Acid-alkaline pretreatment yielded the highest holocellulose composition of 95.26%, with the highest delignification effect of 86.97 ± 1.26%. Furthermore, Fourier transform infrared (FTIR) spectroscopy and X-ray powder diffraction (XRD) validated the acid-alkaline pretreated biomass to be the most feasible substrate for bioethanol production in this study. Finally, the maximum fermentable sugar content and bioethanol concentration of 415.02 ± 7.01 mg/g and 1.57 ± 0.06 mg/ml, respectively, were obtained.

Efficient Saccharification of the Microalga Chlorella vulgaris and its Conversion into Ethanol by Fermentation

The third-generation bioethanol production depends on the utilization of algae as raw material and an excellent source of polysaccharides, which can be fermented to bioethanol. The microalga Chlorella vulgaris is suitable for bioethanol production due to its carbohydrate content. In this study, the chemical pretreatments of acidic and alkaline pretreatments of Chlorella vulgaris biomass showed that the maximum reducing sugars and total carbohydrate concentrations produced from acidic pretreatment of the algal biomass by using 2% sulfuric acid (H2SO4) at 120 °C for 30 min were (24.77 g/100 g dried biomass) and (16.08 g/100 g dried biomass), respectively. The bioethanol released from the biomass was increased gradually until the 5th day (14.32 g/100 g dried biomass). The maximum bioethanol produced after 2% (w/v) of sodium hydroxide (NaOH) at 120 °C for 30 min. alkaline pretreatment was (21.54 g/100 g dried biomass) reducing sugar, (15.72 g/100 g dried biomass) total carbohydrate and the produced bioethanol concentration on the 4th day (7.74 g/100 g dried biomass). At the same time, the physical pretreatments were done by microwaves and ultrasonication. The highest reducing sugars after ultrasonication, (18.97 g/100 g dried biomass) which fermented to (16.19 g/100 g dried biomass) bioethanol at the 4th fermentation day. While microwaves pretreatment reached (11.22 g/ 100 g dried biomass) reducing sugars, that synthesis (2.91 g/100 g dried biomass) at the 5th fermentation day. This work concluded that 2% H2SO4 was the best treatment method, which resulted in the highest concentrations of reducing sugars, total carbohydrate, and bioethanol.

Effects of non-ionic surfactants on bioethanol production using extracted cellulose from wheat straw and kinetic studies

Wheat straw is one of the main by-products of agriculture. The effect of four different non-ionic surfactants, like Tween 20, Tween 80, Polyethylene glycol (PEG) 4000, and PEG 6000, on bioethanol production applying simultaneous saccharification and fermentation (SSF) technology using cellulose extracted from wheat straw as the substrate was investigated in this study. Modified Gompertz model was used to describe the formation kinetics of bioethanol from extracted cellulose. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD) analyses were used to determine the effect of extraction and fermentation on the structure of samples. The results showed that bioethanol concentration increased by 9.62% with the addition of Tween 80. Kinetic studies showed that a maximum bioethanol concentration of 24.84 g/L and a maximum bioethanol production rate of 8.90 g/L/h were observed respectively with the addition of Tween 80. The extraction and fermentation processes had a great influence on the surface and composition of samples by FTIR, SEM, and XRD characterization. This work shows that Tween series surfactants are beneficial to enhance bioethanol production from lignocellulosic biomass.

Bioethanol Production from Cassava Peel Treated with Sulfonated Carbon Catalyzed Hydrolysis

A large amount of Cassava peel as biomass waste is generated by agricultural activities, and it led to a new pursuit to exploit the utilization of biomass waste. This research aimed to study the potential of Cassava peel as raw material for bioethanol production. This study was performed in 2 main processes, acid hydrolysis, and fermentation. The experiment was initiated by conducting acid hydrolysis (100°C and 60 min) on Cassava peel’s starch using sulfonated carbon catalyst palm oil empty fruit bunch (5%-w/v) to produce 13.53 g/L glucose. The glucose contained hydrolysates then continued to ferment at 30°C. The effect of fermentation time (h), pH, and shaking rate (rpm) of cassava peel’s starch fermentation using Saccharomyces cerevisiae was analyzed. The best result was found at pH 4.5 and 50 rpm for a 24 h reaction with 3.75 g/L of bioethanol concentration. This study revealed that Cassava peel is a promising feedstock for biofuel production.

Relative permittivity of bioethanol, gasoline and blends as a function of temperature and composition

The dependence of the real part of the relative permittivity of bioethanol, gasoline, and their blends was determined. Measurements were performed in the temperature range between 298 K and 323 K, at a frequency of 100 kHz. Temperature was stabilized within ±0.1K and the uncertainty in the relative permittivity was ±0.01.In all the studied blends, the real part of the relative permittivity decreases as a function of temperature with a very good fit to a linear function. At each temperature, the real part of the relative permittivity increases with the bioethanol content in the sample.The permittivity as a function of blends composition fits very satisfactorily to a fourth - order polynomial. In all cases, the mean square error (ΔRMS) of the permittivity estimation was less than 0.09. Furthermore, for bioethanol concentrations lower than 25%, a second - order polynomial fits with an ΔRMS error below 0.04. At higher bioethanol concentrations, a linear function fits with an ΔRMS error below 0.13.The bioethanol concentration in the blends is estimated from permittivity and temperature measurements, with a mean square error in the estimation of the composition lower than 0.5% in all cases.This work shows that measurements of electrical properties can be very effective in the characterization of gasoline - ethanol blends for laboratory and industrial applications.

Optimal fed-batch bioreactor operating strategies for the microbial production of lignocellulosic bioethanol and exploration of their economic implications: A step forward towards sustainability and commercialization

The enduring adoption of greener technologies from the biofuel manufacturing industries requires the balanced integration of multiple inter-disciplinary concerns (i.e., engineering, business, sustainability, societal) to make production processes more attractive to the industrial sector. From an engineering perspective, the commercial establishment of lignocellulosic bioethanol plants is still hindered by increased production cost. High product concentrations with improved yield and productivity at the fermentation stage seem to be inviolable condition to straightly compete with fossil-based and first-generation bioethanol facilities. This study proposes a model-based multi-objective dynamic optimization approach to systematically derive optimal operating policies for the fermentation bioreactor as a step forward towards enhancing the economic performance of lignocellulosic bioethanol plants. The economic benefit of the derived optimal bioreactor strategies is evaluated via a scalable economic index, linking for the first time the performance of the fermentation bioreactor to the economics of the entire production process. It is demonstrated that high values in productivity and substantial compromises in yield and final bioethanol concentration are conditions which favor economic feasibility with the achieved fermentation performance (3.32 g L−1 h−1, 0.399 g g−1, 106.0 g L−1) being comparable to first-generation bioethanol production. Finally, a global system analysis framework is employed to investigate the robustness of the optimal value of the economic index to the variability of key model parameters, illustrating the impact of model uncertainty on the process economic performance.

Improving lignocellulosic biofuel production by CRISPR/Cas9‐mediated lignin modification in barley

AbstractBarley is a major cereal crop with a wide ecological range, and its lignocellulosic residues have the potential to be used as a feedstock for various purposes, including biofuel production. Lignocellulosic biomass is an abundant renewable source of carbon energy. However, its heterogeneous properties and intrinsic recalcitrance caused by cell wall lignification have lowered the biorefinery efficiency. The reduced lignin content and/or altered lignin structure have been desirable traits for lignocellulosic feedstock. We report the reduction of lignin content in barley by CRISPR/Cas9‐mediated mutagenesis of caffeic acid O‐methyltransferase 1 (HvCOMT1), the lignin biosynthetic gene responsible for lignin syringyl unit formation. The transgene‐free, homozygous HvCOMT1 mutant was generated and analyzed for its cell wall composition, saccharification efficiency, and bioethanol production performance. The mutant had 14% lower total lignin content and 34% higher fermentable glucose recovery rate, compared to the wild‐type (WT). The bioethanol concentration and yield from the hydrolysates of the mutant biomass were 14.3 g/L and 0.46 g/g total sugar, respectively. This result was 34% and 12% higher than those obtained from WT (10.7 g/L and 0.41 g/g total sugar). Under controlled environmental conditions, the overall growth performance of the HvCOMT1 mutant was similar to WT, with no distinct morphological variations between them. The HvCOMT1 mutant barley could offer improved quality lignocellulosic feedstock for efficient lignocellulosic biofuel production.

The effect of fermentation time and addition of crude cellulase to concentration of bioethanol in bagasse fermentation

Bagasse is a solid waste from the sugar cane milling process in the sugar industry. Bagasse contains lignin, cellulose and hemicellulose, which through the fermentation process by Phanerochaete chrysosporium can produce crude cellulase, furthermore cellulase and other enzymes can be used in bagasse fermentation to produce bioethanol. The purpose of this study was to determine the effect of fermentation time and the addition of crude cellulase to the yield and concentration of bioethanol produced in bagasse fermentation. The research was carried out with the stages of the process: Preparation of raw materials (bagasse), Preparation of crude cellulase, Fermentation process, Product analysis (Bioethanol). The variables used in the experiment were fermentation time (96, 120, and 144 hours) and the addition of crude cellulase (10%, 20%, 30%, 40%, and 50% (v/v)). Analysis of crude cellulase activity using the DNS method, while the analysis of bioethanol concentration using the chromatography methods. The results showed that the maximum yield was 16.24% and the highest bioethanol concentration of 11.04% was obtained at the time of fermentation of 144 hours and the addition of crude cellulase by 50% (v/v).