Highest Bioethanol Research Articles

Recycling of acid-pretreatment hydrolyzates of rice straw for high bioethanol production by S. cerevisiae and P. stipitis fermentation

ABSTRACT The current study developed a strategy to recycle the acid-pretreated hydrolyzate for multiple pretreatments of rice straw to increase the soluble sugar content in the medium, thereby enhancing bioethanol conversion. This process recovered a maximum glucose concentration of 10.4 g/L and xylose: 44.5 g/L in the recycled acid-pretreated rice straw hydrolyzate obtained after the third pretreatment. This resulted in a 2.4-fold increase in glucose recovery and a 2.3-fold increase in xylose recovery compared to the initial pretreatment process. For both glucose and xylose conversion strategies, a co-culture of hexose fermenting S. cerevisiae and P. stipitis, capable of fermenting both pentose and hexoses was employed. The maximum bioethanol titer achieved from the co-culture of S. cerevisiae and P. stipitis was 11.29 g/L. However, applying a sequential culture approach of S. cerevisiae followed by P. stipitis with an intermediate heat inactivation at 50°C resulted in an improvement of bioethanol titer to 12.39 g/L with productivity of 0.258 g/L/h. This led to an improvement in 2.9-fold and 1.2-fold bioethanol titer in comparison to sole fermentation by S. cerevisiae and P. stipitis, respectively. The reuse of acid pretreated hydrolyzate for high recovery of soluble sugar and subsequent fermentation by sequential culture strategy can maximize lignocellulosic bioethanol production.

Distinct lignocelluloses of plant evolution are optimally selective for complete biomass saccharification and upgrading Cd2+/Pb2+ and dye adsorption via desired biosorbent assembly

In this study, 15 plant species representing plant evolution were selected, and distinct lignocellulose compositions for largely varied biomass enzymatic saccharification were detected. By comparison, the acid-pretreated lignocellulose of rice mutant was of the highest Congo-red adsorption (298 mg/g) accounting for cellulose accessibility, leading to complete cellulose hydrolysis and high bioethanol production. By conducting oxidative-catalysis with the acid-pretreated lignocellulose of moss plant, the optimal biosorbent was generated with maximum Cd/Pb adsorption (54/118 mg/g), mainly due to half-reduced cellulose polymerization degree and raised functional groups accountable for multiple physical and chemical interactions. Furthermore, the acid-pretreated lignocellulose of eucalyptus was of large and small pores for much higher adsorption capacities with direct-yellow and direct-blue than those of the previously-reported. Therefore, this study raises a mechanism model about how distinct lignocelluloses of plant evolution are selective for complete biomass saccharification and optimal biosorbents assembly, providing insights into lignocellulose biosynthesis and biomass conversion.

Pengaruh Konsentrasi Enzim, Ragi, dan Lama Fermentasi terhadap Pembuatan Bioetanol Berbahan Baku Chlorella pyrenoidosa

The demand for energy is inversely proportional to the current amount of energy in Indonesia. In order to face this problem, it is necessary to develop renewable energy sources. This study was conducted to analyze enzymes effect in the Chlorella pyrenoidosa hydrolysis, analyze yeast effect and the fermentation time of Chlorella pyrenoidosa on the bioethanol produced. The variables used are variation of α-amylase enzyme concentration of 25%, 35%, 45% (v/w), and variation of yeast concentration of 5%, 10%, 15% (w/v) and fermentation time of 7, 9, 11 days. From the analysis conducted, the highest glucose content was 13.119%, which was in the variation of 45% (v/w) α-amylase enzyme concentration. The amount of enzyme concentration used was in accordance with glucose production. The highest bioethanol was obtained with a sample involving 10% (v/b) yeast fermented for 9 days, which amounted to 27%.

Renewable Energy Potential: Second-Generation Biomass as Feedstock for Bioethanol Production.

Biofuels are clean and renewable energy resources gaining increased attention as a potential replacement for non-renewable petroleum-based fuels. They are derived from biomass that could either be animal-based or belong to any of the three generations of plant biomass (agricultural crops, lignocellulosic materials, or algae). Over 130 studies including experimental research, case studies, literature reviews, and website publications related to bioethanol production were evaluated; different methods and techniques have been tested by scientists and researchers in this field, and the most optimal conditions have been adopted for the generation of biofuels from biomass. This has ultimately led to a subsequent scale-up of procedures and the establishment of pilot, demo, and large-scale plants/biorefineries in some regions of the world. Nevertheless, there are still challenges associated with the production of bioethanol from lignocellulosic biomass, such as recalcitrance of the cell wall, multiple pretreatment steps, prolonged hydrolysis time, degradation product formation, cost, etc., which have impeded the implementation of its large-scale production, which needs to be addressed. This review gives an overview of biomass and bioenergy, the structure and composition of lignocellulosic biomass, biofuel classification, bioethanol as an energy source, bioethanol production processes, different pretreatment and hydrolysis techniques, inhibitory product formation, fermentation strategies/process, the microorganisms used for fermentation, distillation, legislation in support of advanced biofuel, and industrial projects on advanced bioethanol. The ultimate objective is still to find the best conditions and technology possible to sustainably and inexpensively produce a high bioethanol yield.

Optimization of Some Fermentation Conditions for Bioethanol Production from Yam Peels (Dioscorea rotundata) Using Box-Behnken Design (BBD)

Aim: The aim of this research was to optimize the production of bioethanol from a select second generation feedstock (yam peels).
 Methodology: Bioethanol was produced from yam peels using Box Behnken Design (BBD). The independent variables selected for optimization of bioethanol yield were; fermentation temperature (˚C), fermentation time (hours) and yeast concentration (%w/v). A set of 17 experiments were considered by design expert software. All experiments were run in triplicates. Test for bioethanol was carried out using acidified potassium dichromate method and absorbance was taken using a spectrophotometer at 600nm.
 Results: From the experiments carried out above, the optimum conditions under which the highest bioethanol (yield%) was produced were a fermentation temperature of 30̊C, yeast concentration of 5.50%w/v and fermentation time of 96hours under which a bioethanol yield of 45.79% was produced.
 Conclusion: Yam peels may therefore have the potentials to serve as substrates for bioethanol production rather than using food crops such as sugarcane juice and cassava flesh which may lead to food shortages and crisis especially is developing countries such as Nigeria.

Full-Chain FeCl3 Catalyzation Is Sufficient to Boost Cellulase Secretion and Cellulosic Ethanol along with Valorized Supercapacitor and Biosorbent Using Desirable Corn Stalk

Cellulosic ethanol is regarded as a perfect additive for petrol fuels for global carbon neutralization. As bioethanol conversion requires strong biomass pretreatment and overpriced enzymatic hydrolysis, it is increasingly considered in the exploration of biomass processes with fewer chemicals for cost-effective biofuels and value-added bioproducts. In this study, we performed optimal liquid-hot-water pretreatment (190 °C for 10 min) co-supplied with 4% FeCl3 to achieve the near-complete biomass enzymatic saccharification of desirable corn stalk for high bioethanol production, and all the enzyme-undigestible lignocellulose residues were then examined as active biosorbents for high Cd adsorption. Furthermore, by incubating Trichoderma reesei with the desired corn stalk co-supplied with 0.05% FeCl3 for the secretion of lignocellulose-degradation enzymes in vivo, we examined five secreted enzyme activities elevated by 1.3-3.0-fold in vitro, compared to the control without FeCl3 supplementation. After further supplying 1:2 (w/w) FeCl3 into the T. reesei-undigested lignocellulose residue for the thermal-carbonization process, we generated highly porous carbon with specific electroconductivity raised by 3-12-fold for the supercapacitor. Therefore, this work demonstrates that FeCl3 can act as a universal catalyst for the full-chain enhancement of biological, biochemical, and chemical conversions of lignocellulose substrates, providing a green-like strategy for low-cost biofuels and high-value bioproducts.

High bioethanol titer and yield from phosphoric acid plus hydrogen peroxide pretreated paper mulberry wood through optimization of simultaneous saccharification and fermentation

The optimization of key simultaneous saccharification and fermentation (SSF) parameters for bioethanol production from phosphoric acid plus hydrogen peroxide pretreated paper mulberry wood was carried out under two isothermal scenarios; the yeast optimum and trade-off temperatures of 35 and 38 °C, respectively. The optimal conditions established for SSF at 35 °C (solid loading: 16%; enzyme dosage: 9.8 mg protein/g glucan; and yeast concentration: 6.5 g/L) achieved high ethanol titer and yield of 77.34 g/L and 84.60% (0.432 g/g), respectively. These corresponded to 1.2 and 1.3-folds increases, compared to the results of the optimal SSF at a relatively higher temperature of 38 °C. The information from this study would prove beneficial in reducing process energy demands to some extent, while also helping to achieve high levels of both ethanol concentration and yield that are desired in cellulosic ethanol production.

The Important Roles of Ecomychorizae to Increase Growth Rate of Sacha Inchi (Plukenetia volubilis L.) that Potentially as Raw Material of Biofuel

Recently the use of agricultural waste containing cellulose and lignin as an alternative fuel that is environmentally friendly. The study aimed to determine the important roles of eco-enzymes and mycorrhizae due to increasing the growth rate of sacha inchi plants that are tolerant to nutrient-poor soils such as Inceptisol which are classified as sub-optimal lands. Sacha inchi broadleaf plants are classified as having a high lignin content due to their biomass potentially producing alternative fuels that can reduce dependence on the use of fossils, which were decreasing. This research was conducted in West Reuleut Village, Muara Batu District, North Aceh District and the Laboratory of the Faculty of Agriculture, Malikussaleh University. This research was carried out from April to August 2022.The Application of eco-enzymes on Inceptisol soil has increased the absorption of several macronutrients that were impacted by the fresh weight of the root, root dry weight, and root length of sacha inchi. The activities of eco enzyme and mycorrhizae which were giving a positive impact on the vegetative growth rate of Sacha inchi plants. Eco enzymes contain microorganisms that help the process of decomposition, transport of nutrients, and mycorrhizae as biological fertilizers that can provide nutrient uptake for plants. The impact of synergizing both fertilizers together has increased the suitability and productivity of sub-optimal soil that is able to increase growth and yield plant. The increasing productivity of Sacha inchi plants which contain lignin and cellulose also increases plant biomass which has the potential to produce high bioethanol as well.

Strategic combination of different promoters in lactose metabolisation and host chassis selection for high bioethanol titres from dairy wastes

The yeast Saccharomyces cerevisiae is widely used in biotechnological processes but is unable to metabolise lactose, the main component of cheese whey. Here, we engineered industrial S. cerevisiae strains for bioethanol fermentation from lactose. Heterologous expression of LAC12 and LAC4 from Kluyveromyces lactis, encoding for a lactose permease and a β-galactosidase, respectively, under different promoter combinations (TEF1p/PGK1p), generated the strains E1 (TEF1p → LAC4/PGK1p → LAC12) and E2 (PGK1p → LAC4/TEF1p → LAC12). In synthetic media, E1 exhibits faster lactose consumption up to 150 g/L of lactose, while E2 exhibits improved lactose metabolisation ability at 200 g/L of lactose with a yield near 100%. These results were validated in whey where the strain E2 produced 92.2 g/L of ethanol from 200 g/L lactose, the highest titre reported in the literature from whey. This study provides valuable insight on how the promoter choice influences multi-enzymatic step pathways and the importance of selecting an appropriate host for high-titre processes.

Identification of Genetic Loci for Sugarcane Leaf Angle at Different Developmental Stages by Genome-Wide Association Study.

Sugarcane (Saccharum spp.) is an efficient crop mainly used for sugar and bioethanol production. High yield and high sucrose of sugarcane are always the fundamental demands in sugarcane growth worldwide. Leaf angle and size of sugarcane can be attributed to planting density, which was associated with yield. In this study, we performed genome-wide association studies (GWAS) with a panel of 216 sugarcane core parents and their derived lines (natural population) to determine the genetic basis of leaf angle and key candidate genes with +2, +3, and +4 leaf at the seedling, elongation, and mature stages. A total of 288 significantly associated loci of sugarcane leaf angle at different developmental stages (eight phenotypes) were identified by GWAS with 4,027,298 high-quality SNP markers. Among them, one key locus and 11 loci were identified in all three stages and two stages, respectively. An InDel marker (SNP Ss6A_102766953) linked to narrow leaf angle was obtained. Overall, 4,089 genes were located in the confidence interval of significant loci, among which 3,892 genes were functionally annotated. Finally, 13 core parents and their derivatives tagged with SNPs were selected for marker-assisted selection (MAS). These candidate genes are mainly related to MYB transcription factors, auxin response factors, serine/threonine protein kinases, etc. They are directly or indirectly associated with leaf angle in sugarcane. This research provided a large number of novel genetic resources for the improvement of leaf angles and simultaneously to high yield and high bioethanol production.

Enhanced bioethanol-to-ethylene performance over nanosized sheet-like M-SAPO-34 (M = Sr and K) catalysts

Two-dimensional (2D) morphology zeolites nanosheets NS-M-SAPO-34 (M = K and Sr) were developed and applied for producing ethylene (C2H4) from bioethanol. Various factors, including SAPO-34 type, temperature, bioethanol concentration, and weight hourly space velocity (WHSV) on C2H4 production were evaluated. The synthesized NS-M-SAPO-34s gave a nanosheet-like morphology with a thickness of 25–50 nm, while the commercial cube-like SAPO-34 (CC-SP34) exhibited a cubic-like morphology with a particle size of about 1.5 μm. The specific surface area of the NS-Sr-SAPO-34 was 644 m2 g−1 which was much larger than that of CC-SP34 (573 m2 g−1). The catalytic performance evaluated by bioethanol dehydration reaction showed that NS-Sr-SAPO-34 exhibited significant improvements not only in suppressed coke deposition (5.6%) and prolonged lifetime (913 min) but also in higher C2H4 yield (94.5%) compared with those (11.8%, 160 min and 82.4%, respectively) of CC-SP34, which can be attributed to the shortened diffusion path length, highly accessible active centers and suitable medium-strong acidity. Elevated temperature, high bioethanol concentration and decreased WHSV tended to enhance the C2H4 yield, while decreased bioethanol concentration was propitious to suppress coking rate. An optimal C2H4 yield of 100% was obtained at 350 °C with a bioethanol concentration from nutrient broths (15 vol%, WHSV = 0.75 h−1).

Assessing the Potentials of Some Agro-Waste Peels Through Proximate Analysis

The economic potentials of some agro-waste peels were evaluated using proximate analysis. The substratesinvestigated were pineapple peels, banana peels, plantain peels, cassava peels, yam peels and potato peels. Their bioethanol productionpotentials were evaluated using their % carbohydrate content while their animal feedproductionpotentials were evaluated using their total energy content on a dry weight bases. On comparative assessment, it was deduced that potato peels had the highest bioethanol production potential (84.64% carbohydrate content) while pineapple peels had the least (54.89% carbohydrate content). It was also deduced that potato peels had the highest animal feed production potential (383.04 Kcal/100g) while cassava peels had the least (356.84 Kcal/100g). Minerals were also found to be highest in plantain peels (11.41% ash) and cassava peels (9.85% ash). This research revealedthat all the considered substrates were good sources of carbohydrates and energy when completely dried, although in varying degree.

Enhancement of Fermentable Sugars Obtained from<i> Amorphophallus</i> Spp. Tuber for Bioethanol Production by Optimizing Temperature and Pretreatment Concentration

Biofuels have been regaining popularity due to the increasing price of non-renewable fuels and the higher carbon dioxide emissions. Biofuels are manufactured from plant products and are mainly composed of lignocellulose and starch materials. This investigation aims to produce increased fermentable sugars for enhanced bioethanol production from tubers procured from northern Thailand. Varying concentrations of H2SO4 is used to pretreat the tubers. Before hydrolyzing with cellulase enzymes, the tubers were chopped into small pieces (1-2 cm), dried in a solar oven, powdered. The obtained results confirmed that the fermentable/ reducing sugar content of Amorphophallus spp. (suweg) tuber increased from 2.6 g/L to 19.01 g/L after enzymatic hydrolysis. The enzymes act as an excellent way to speed up the hydrolysis process. The theoretical potential of bioethanol production was calculated under ideal conditions, with the highest bioethanol concentration obtained is 9.69 ± 0.12 g/L at 0.4 % H2SO4 (pretreatment conc.) and 75 °C. The enhanced fermentable sugars obtained from starchy tubers may be utilized for bioethanol production to overcome depleting fossil fuels.

Comparative Studies On Bioethanol Production From Some Starch Based Agricultural Waste Peels

The potential of some starch-based agricultural waste peels (cassava peels, yam peels and potato peels) for bioethanol production was investigated. They were pretreated with physico-chemical agents before being hydrolyzed using cellulase enzymes from the Trichoderma ressei micro-organism. Using co-cultures of Saccharomyces cerevisiae and Pichia stipitis fermentative yeasts, the different hydrolysates were fermented to bioethanol. The bioethanol yields of separate hydrolysis and co-fermentation (SHCF) and simultaneous saccharification and co-fermentation (SSCF) fermentative procedures were evaluated. The maximum bioethanol yields from the fermentation results for cassava peels, yam peels and potato peels were 4.87, 3.78 and 5.31 (% w/v wet biomass) respectively after 72 hours of fermentation. The SSCF method was shown to be more successful since it produced higher bioethanol yields in all of the substrates studied and was quicker. When compared to prior research using different microorganisms, the SSCF technique had a superior fermentation yield using mixed cultures of Trichoderma ressi, Saccharomyces cerevisiae and Pichia stipites.

Integrating mild chemical pretreatments with endogenous protein supplement for complete biomass saccharification to maximize bioethanol production by enhancing cellulases adsorption in novel bioenergy Amaranthus

Amaranthus is a fast-growing perennial plant containing large amounts of extractable green proteins and lignocellulose residues. However, it remains to explore optimal Amaranthus biomass process technology for biofuel production. In this study, we examined that mild alkali and acid pretreatments (1% NaOH, 2% H2SO4) were sufficient for near-complete biomass enzymatic saccharification, while 8% Amaranthus endogenous proteins were supplemented into the enzymatic hydrolyses. By performing classic yeast fermentation with all carbon sources from directly-extractable sugars and starch and lignocellulose enzymatic hydrolysis, this work achieved the bioethanol yield up to 23.5% (% dry matter). Notably, with respect to extremely high yield of Amaranthus straw, the maximum bioethanol yield was estimated at 14.46 t/ha/year, which was much higher than those of other major bioenergy crops as previously reported. Furthermore, this work proposed a hypothetic model to elucidate how the complete biomass saccharification was achieved to maximize bioethanol production at large scale, based on the effective wall polymer extraction and distinct lignocellulose feature modification for remarkably enhanced biomass porosity and cellulases adsorption. Hence, this work has demonstrated that Amaranthus could be applied as a novel and leading bioenergy crop, providing a powerful strategy for optimal biomass processing towards high bioethanol production.

Distinct cellulose nanofibrils generated for improved Pickering emulsions and lignocellulose-degradation enzyme secretion coupled with high bioethanol production in natural rice mutants

Distinct cellulose nanofibrils generated for improved Pickering emulsions stabilization and mixed-cellulases induction coupled with high bioethanol production in natural rice mutant.

Integrated genetic and chemical modification with rice straw for maximum bioethanol production

Crop straw provides huge lignocellulose residues that are transformable for bioethanol production and biochemicals. However, lignocellulose recalcitrance fundamentally causes a costly biomass process that is unapplicable for bioethanol conversion at industrial level with potential waste release. Here, this study selected the transgenic rice (Oryza sativa L.) lines that overexpressed AtCesA6, a typical gene involved in cellulose biosynthesis of primary cell walls in Arabidopsis (Arabidopsis thaliana L Heynh.). This work then examined significantly improved lignocellulose substrates along with much soluble sugars deposition in the transgenic rice straws. By performing green-style pretreatments with mature rice straws using two recyclable and relatively low-cost alkali chemicals (NH3·H2O, CaO) and liquid hot water, this work determined almost complete enzymatic saccharification in the transgenic rice lines. Notably, under two optimal alkali pretreatments, the transgenic rice samples could achieve either bioethanol yields of more than 20 % (% dry matter) or bioethanol concentrations at 18.3 g/L and 19.1 g/L from one-pot relatively high solid loading saccharification, being much higher than those of wild type (Nipponbare). Furthermore, this study examined how the lignocellulose recalcitrance was significantly reduced for remarkably raised enzymatic saccharification in the transgenic rice straws. It also explicated that the maximum bioethanol yield obtained in the transgenic straws should mainly be subjective to near-complete enzymatic saccharification and much directly-fermentable soluble sugars accumulation. Therefore, this study has provided a novel strategy for high bioethanol production by integrating genetically-improved lignocellulose substrates with optimal one-pot-process technology in bioenergy crops.

Enzymatic hydrolysis and fermentation strategies for the biorefining of pine sawdust

This work aims to evaluate second-generation bioethanol production from the soda-ethanol pulp of pine sawdust via two strategies: separate hydrolysis and fermentation and simultaneous saccharification and fermentation. A kinetics study of the enzymatic hydrolysis of separate hydrolysis and fermentation was included as a design tool. Three soda-ethanol pulps (with different chemical compositions), Cellic® Ctec2 cellulolytic enzymes, and Saccharomyces cerevisiae IMR 1181 (SC 1181) yeast were employed. The obtained kinetic parameters were as follows: an apparent constant (k) of 11.4 h-1, which represents the link frequency between cellulose and cellulase; a Michaelis-Menten apparent constant (KM) of 23.5 gL-1, that indicates the cellulose/cellulase affinity; and the apparent constant of inhibition between cellulose-glucose and cellulase (KI), which was 2.9 gL-1, 3.1 gL-1, and 6.6 gL-1 for pulps 1, 2, and 3, respectively. The kinetic model was applicable, since the calculated glucose values fit the experimental values. High bioethanol yields were obtained for pulp 3 in the separate hydrolysis and fermentation and simultaneous saccharification and fermentation processes (89.3% and 100% after 13 h and 72 h, respectively).

Mushroom-mediated delignification of agricultural wastes for bio-ethanol production

Biological pretreatment is a cost-effective method of delignifying lignocellulosic biomass, making it less recalcitrant to hydrolysis into fermentable sugars. In this study, selected agricultural wastes were pretreated with mushrooms (Lentinus squarrosulus and Pleurotus ostreatus) to delignify them for bioethanol production. The substrates were supplemented with 0.2 % CaCO3, inoculated with 12 % (w/w) L. squarrosulus and Pleurotus ostreatus spawns and incubated at 25 oC for 21 days. The highest lignin removal and highest bioethanol yield of 77.45 % and 13.98 % were obtained from bean husks pretreated with L. squarrosulus. Similarly, 64.29 % and 60.92 % lignin were removed from the Pleurotus ostreatus-pretreated banana leaves and sawdust, respectively, while 12.08 % and 13.05 % bio-ethanol yields were recorded, respectively. These findings demonstrate that affordable and straightforward mushroom delignification of abundant and cheap biomass can improve hydrolysis outcomes, thus easing bioethanol production.

Diverse Banana Pseudostems and Rachis Are Distinctive for Edible Carbohydrates and Lignocellulose Saccharification towards High Bioethanol Production under Chemical and Liquid Hot Water Pretreatments

Banana is a major fruit crop throughout the world with abundant lignocellulose in the pseudostem and rachis residues for biofuel production. In this study, we collected a total of 11 pseudostems and rachis samples that were originally derived from different genetic types and ecological locations of banana crops and then examined largely varied edible carbohydrates (soluble sugars, starch) and lignocellulose compositions. By performing chemical (H2SO4, NaOH) and liquid hot water (LHW) pretreatments, we also found a remarkable variation in biomass enzymatic saccharification and bioethanol production among all banana samples examined. Consequently, this study identified a desirable banana (Refen1, subgroup Pisang Awak) crop containing large amounts of edible carbohydrates and completely digestible lignocellulose, which could be combined to achieve the highest bioethanol yields of 31–38% (% dry matter), compared with previously reported ones in other bioenergy crops. Chemical analysis further indicated that the cellulose CrI and lignin G-monomer should be two major recalcitrant factors affecting biomass enzymatic saccharification in banana pseudostems and rachis. Therefore, this study not only examined rich edible carbohydrates for food in the banana pseudostems but also detected digestible lignocellulose for bioethanol production in rachis tissue, providing a strategy applicable for genetic breeding and biomass processing in banana crops.