Fuel Ethanol Production Research Articles

Novel class of aldehyde reductases identified from Scheffersomyces stipitis for detoxification processes in cellulosic ethanol production industry

The increase in industrialization has led to a significant energy crisis, sparking interest in lignocellulosic biomass for fuel ethanol production because of its renewable characteristics. The complex composition of this biomass requires pretreatment to reduce inhibitors like furfural and hydroxymethylfurfural (HMF), which hinder enzymatic hydrolysis and fermentation, ultimately decreasing ethanol yields. This study investigates the detoxification mechanisms of furan aldehydes in Scheffersomyces stipitis, particularly through the upregulation of genes SsOYE2.2, SsOYE2.7, and SsOYE3.1 under furfural and HMF stress. Enzyme characterization determined that SsOye3.3p is the most active enzyme for reducing both compounds using NADPH. Notably, SsOye2.6p showed the highest catalytic efficiency towards furfural, while SsOye2.8p was optimal for HMF. The study also established the optimal temperature and pH for these enzymatic reactions. Importantly, SsOye2.5p displayed broad substrate specificity, indicating its potential in detoxifying various aldehydes in microbial cells. The findings suggest that genes linked to enhanced enzymatic properties were not significantly induced, indicating that S. stipitis has more substantial potential for furan aldehyde detoxification and can be developed as a chassis organism exhibiting furan aldehyde tolerance. These insights facilitate the development of novel enzymes to counter furan aldehyde inhibitors and the creation of furan aldehyde-tolerant strains via genetic engineering.

Highly Efficient Production of Cellulosic Ethanol from Poplar Using an Optimal C6/C5 Co-Fermentation Strain of Saccharomyces cerevisiae.

Cellulosic ethanol is the key technology to alleviate the pressure of energy supply and climate change. However, the ethanol production process, which is close to industrial production and has a high saccharification rate and ethanol yield, still needs to be developed. This study demonstrates the effective conversion of poplar wood waste into fuel-grade ethanol. By employing a two-step pretreatment using sodium chlorite (SC)-dilute sulfuric acid (DSA), the raw material achieved a sugar conversion rate exceeding 85% of the theoretical value. Under optimized conditions, brewing yeast co-utilizing C6/C5 enabled a yield of 35 g/L ethanol from 10% solid loading delignified poplar hydrolysate. We increased the solid loading to enhance the final ethanol concentration and optimized both the hydrolysis and fermentation stages. With 20% solid loading delignified poplar hydrolysate, the final ethanol concentration reached 60 g/L, a 71.4% increase from the 10% solid loading. Our work incorporates the pretreatment, enzymatic hydrolysis, and fermentation stages to establish a simple, crude poplar waste fuel ethanol process, expanding the range of feedstocks for second-generation fuel ethanol production.

Comprehensive Evaluation of Fuel Ethanol Production from Poplar Wood Fermentation and its Coupled Pathway with Lignin Gasification Based on Energy-Environment-Economy

Comprehensive Evaluation of Fuel Ethanol Production from Poplar Wood Fermentation and its Coupled Pathway with Lignin Gasification Based on Energy-Environment-Economy

Optimization and benefit analysis of the supply chain for sweet sorghum bioenergy production in China

<p>Bio-liquid fuel is one of the effective ways to alleviate energy shortages and reduce greenhouse gas emissions. Sweet sorghum, as an energy crop used in fuel ethanol production, has enormous potential for development. However, due to seasonality, vulnerability, and logistical scheduling costs during transportation, the sweet sorghum ethanol supply chain faces significant difficulties and challenges in its development. To address the research gap, this paper proposes a multi-objective sustainable supply chain optimization model for Chinese sweet sorghum bioenergy based on mixed-integer linear programming. In this framework, the crop growth process model is first spatially extended to obtain the feedstock sources of the sweet sorghum ethanol supply chain. Then a site selection model for the feedstock collection stations and ethanol processing plants is constructed based on the geographic information system (GIS) to determine the candidate locations of the basic units of the sweet sorghum ethanol supply chain. Finally, a multi-objective supply chain optimization model based on the mixed-integer linear programming methodology is created to achieve the sweet sorghum ethanol supply chain layout and optimization at the national level. This framework takes into account the fuel ethanol market demand in China and the current state of the sweet sorghum ethanol supply chain industry, achieving national-level layout and optimization of the sweet sorghum ethanol supply chain. The total aboveground biomass (dry weight) of sweet sorghum on marginal land in China can be converted into approximately 37.212 million tons of fuel ethanol production, meeting the requirement to promote a nationwide 10% substitution rate for automotive ethanol gasoline. The lowest-cost supply chain layout scheme suggests establishing large ethanol processing plants near the Hu Huanyong Line, as this area benefits from abundant sweet sorghum yield on marginal lands and lower east-west direction transportation costs. However, the lowest carbon emission supply chain layout scheme recommends reducing the raw material supply area and increasing the ethanol transportation route to lower carbon emissions. The results of the sensitivity analyses indicate that lowering feedstock production and increasing ethanol demand increases the overall cost and carbon emissions of the sweet sorghum ethanol supply chain, while using rail transportation methods, increasing feedstock production, and decreasing ethanol demand reduces costs and carbon emissions.</p>

APPLICATION OF ALTERING PRESSURE IMPULSES FOR DELIGNIFICATION OF WHEAT STRAW

Based on the growth of global energy demand, the limitation of fossil energy sources, and the growth of greenhouse gas emissions due to the use of fuels based on them, there is a need for wider use of renewable energy sources in particular biomass. The main purpose of the stage of pretreatment of lignocellulosic raw materials for hydrolysis in the second-generation fuel ethanol production technology is to destroy the heterogeneous matrix, increase the surface area and porosity of the cellulosic material, and release carbohydrates from the lignin bond, thereby improving enzymatic digestibility. The aim of the study is to compare the effect of alternating impulses of pressure and autoclaving on lignin removal during the pretreatment of wheat straw for enzymatic hydrolysis in the technology of fuel ethanol production. It was determined that increasing the alkali concentration from 0.5 to 4 % wt. reduces the lignin content in the sample from 51.0 to 24.5 % of the initial content for autoclaving at 90 °С, at 121 °С the content of lignin decreases from 40.6 to 17.5 %. Processing at a temperature of 90 °С reduces the lignin content from 43.0 to 18.5 %. The minimum lignin content in the sample was 18.5 % of the initial content for autoclaving at 90 °C for 60 min process, at 121 °С the minimum content of lignin in the sample and the amount of released lignin was observed for 60 min and amounted to 17.5 %. Processing leads to the lignin content in the sample up to 17.5 % for 120 min. The minimum content of lignin in the sample for autoclaving was 17.5 % at 121 °С. For processing, the maximum value of removed lignin was 18.5 % at 90 °С. It was determined that the addition of alternating pressure pulses allows, at atmospheric pressure and a temperature lower than 100 °С, to obtain a degree of lignin removal comparable to the degree of lignin removal in an autoclave at a temperature of 121 °С, which is usually the basis for the process of pretreatment of plant raw materials for hydrolysis in the technology of obtaining fuel ethanol. Bibl. 16, Fig. 5.

Extraction and Characterization of Forest Anchomanes (Anchomanes difformis (Bl.) ENGL.) Starch for Fuel Production

The use of cassava for fuel ethanol production in Nigeria is supported by the Nigerian Biofuel Policy and Incentives (NBPI) of 2007. Because of its food, feed and industrial value, the need to replace cassava with crops/plants that are food and feeds neutral has motivated this research. Starch was extracted from forest anchomanes (FA) (Anchomanes difformis (Bl.) ENGL.) tubers and some of its physicochemical and elemental properties were determined. At present, the plant is uncultivated in Nigeria and other parts of Africa where it is found. Results showed that the starch content in FA tubers varied from 72.12 to 75.83%. Starch granules from all parts of the FA tubers had similar proximate, antinutrients and elemental properties and appeared usable for fuel ethanol production. However, to suggest its potential to sustainably replace cassava, further investigations are needed beyond these initial results.

Life Cycle Assessment of Fuel Ethanol Production from Food Waste in Consideration of By-Product Utilization

In this paper, a life cycle assessment was used to evaluate fuel ethanol production from food waste with a capacity of 20 tons/day. The energy and pollution emissions during the whole process were recorded and compared by the method of electricity conversion to standard coal. Different indicators, such as GWP (global warming potential), ODP (ozone depletion potential), AP (acid potential), EP (possibility of eutrophication), POCP (photochemical oxidation potential), and DUST (dust), were used to perform an environmental impact analysis with and without by-product utilization. The result shows that the indicator sequence under the weighted factor sequence was AP > DUST > GWP > ODP > EP > POCP. The consideration of by-products decreased the values of GWP, AP, and DUST significantly; EP declined slightly; ODP and POCP increased; and the overall energy output was negative. The consideration of by-product utilization was determined to be environmentally friendly.

Omics Sequencing of Saccharomyces cerevisiae Strain with Improved Capacity for Ethanol Production

Saccharomyces cerevisiae is the most important industrial microorganism used to fuel ethanol production worldwide. Herein, we obtained a mutant S. cerevisiae strain with improved capacity for ethanol fermentation, from 13.72% (v/v for the wild-type strain) to 16.13% (v/v for the mutant strain), and analyzed its genomic structure and gene expression changes. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment revealed that the changed genes were mainly enriched in the pathways of carbohydrate metabolism, amino acid metabolism, metabolism of cofactors and vitamins, and lipid metabolism. The gene expression trends of the two strains were recorded during fermentation to create a timeline. Venn diagram analysis revealed exclusive genes in the mutant strain. KEGG enrichment of these genes showed upregulation of genes involved in sugar metabolism, mitogen-activated protein kinase pathway, fatty acid and amino acid degradation, and downregulation of genes involved in oxidative phosphorylation, ribosome, fatty acid and amino acid biogenesis. Protein interaction analysis of these genes showed that glucose-6-phosphate isomerase 1, signal peptidase complex subunit 3, 6-phosphofructokinase 2, and trifunctional aldehyde reductase were the major hub genes in the network, linking pathways together. These findings provide new insights into the adaptive metabolism of S. cerevisiae for ethanol production and a framework for the construction of engineered strains of S. cerevisiae with excellent ethanol fermentation capacity.

Influence of mineral ions on the growth and fermentation performance of Dekkera bruxellensis GDB248.

The excess of minerals in the industrial substrates is detrimental for Saccharomyces cerevisiae ethanol fermentation performance. In this work, we sought to understand the effect of some of those minerals on the physiology of Dekkera bruxellensis. Three groups of minerals were classified on the basis of the aerobic growth profiles on glucose: neutrals (K+, Mg2+, P5+ and Zn2+), inducers (Mn2+ and Ca2+) and inhibitors (Al3+, Cu2+ and Fe2+). Cu2+ showed the highest mineral toxicity, and its effect was dependent of the level of medium aeration. On the other hand, copper stimulated respiration by increasing growth on respiratory carbon sources. Most growth inhibitors also hampered glucose fermentation, with changes in carbon distribution to metabolic routes dedicated to anabolic reactions and for alternative reduced co-factors oxidations to maintain cellular homeostasis. The negative effect of Cu2+ on yeast fermentation was partially alleviated by Mg2+ and Mn2+, similar to magnesium antagonism observed for S. cerevisiae. All these results might contribute to understand the action of these minerals in sugarcane substrates on the physiology of D. bruxellensis cells. Therefore, it represents one more step for the consolidation of the industrial use of this yeast in the production of fuel-ethanol as well as other biotechnological goods.

Physical and chemical evolution of sugar beet pulp during aqueous ammonia pretreatment and its impacts on the recalcitrance of cellulose

Recognition and deconstruction of biomass recalcitrance are essential steps in fuel ethanol production. Aqueous ammonia (AA) is an efficient pretreatment to improve the enzymatic digestibility of sugar beet pulp (SBP), but the precise mechanism is still ambiguous. Multidimensional methods, e.g., physical properties, wet chemistry compositions, and glycome profiling were integrated to elucidate the impacts of AA pretreatment on recalcitrance of SBP semi-quantitatively. Additionally, the variations in enzyme adsorption and cell wall morphology during the enzymatic hydrolysis were systematically observed. The results confirmed that the constitution, association, and distribution of glycan epitopes within cell walls significantly correlated to recalcitrance. Specifically, the arabinogalactan and rhamnogalacturonan epitopes negatively correlated to the recalcitrance. And xylans only bound to cellulose contributed to recalcitrance. Dislocation and fragmentation of cell walls through sequential removal of several glycan epitopes could facilitate enzymatic digestibility, in terms of enzyme adsorption, reducing sugar yields, and enzymatic saccharification behaviors. Whereas, cell corners seemed to be highly resistant to enzymatic digestion due to some gathered epitopes. The maximum reducing sugar yields ranging from 437.7 to 441.48 mg/g were obtained from the pretreated SBP (3, 5, and 7 h), which nearly increased by 87% compared to the control. Selecting a proper pretreatment to precisely strip out the vital glycan epitopes might be an economically feasible strategy in fuel ethanol production.

Increasing Ethanol Tolerance and Ethanol Production in an Industrial Fuel Ethanol Saccharomyces cerevisiae Strain

The stress imposed by ethanol to Saccharomyces cerevisiae cells are one of the most challenging limiting factors in industrial fuel ethanol production. Consequently, the toxicity and tolerance to high ethanol concentrations has been the subject of extensive research, allowing the identification of several genes important for increasing the tolerance to this stress factor. However, most studies were performed with well-characterized laboratory strains, and how the results obtained with these strains work in industrial strains remains unknown. In the present work, we have tested three different strategies known to increase ethanol tolerance by laboratory strains in an industrial fuel–ethanol producing strain: the overexpression of the TRP1 or MSN2 genes, or the overexpression of a truncated version of the MSN2 gene. Our results show that the industrial CAT-1 strain tolerates up to 14% ethanol, and indeed the three strategies increased its tolerance to ethanol. When these strains were subjected to fermentations with high sugar content and cell recycle, simulating the industrial conditions used in Brazilian distilleries, only the strain with overexpression of the truncated MSN2 gene showed improved fermentation performance, allowing the production of 16% ethanol from 33% of total reducing sugars present in sugarcane molasses. Our results highlight the importance of testing genetic modifications in industrial yeast strains under industrial conditions in order to improve the production of industrial fuel ethanol by S. cerevisiae.

Process design and techno-economic analysis of fuel ethanol production from food waste by enzymatic hydrolysis and fermentation

In this study, fuel ethanol production from food waste using enzymatic hydrolysis and fermentation was evaluated from techno-economic viewpoint. The plant was designed with a capacity of 10 t/d food waste and a lifetime of 15-year. The total capital cost, annual operation cost and annual net profits of the plant were US$ 367,552, US$ 155,959 and US$ 74,995.57, respectively. The plant was economically viable as long as the internal rate of return remained below 29.8%. The shortest payback time was 5 years with discount rate of 5%. The price of fuel ethanol and food waste treatment fee were the most important variables for the economic performance of the plant by sensitivity analysis. This work could provide the basic knowledge for techno-economic analysis of food waste treatment and promote the industrial production of fuel ethanol.

Co-movements and causalities between ethanol production and corn prices in the USA: New evidence from wavelet transform analysis

The literature has been increasingly examining the existence of possible compatibility or conflict hypotheses between biofuels and food security in recent years. While current research outputs do not provide a consensus, the new evidence can guide sustainable development policies. In this context, this paper investigates the co-movements between fuel ethanol production and corn prices for the US employing oil production, population, and real exchange rate control variables via the Morlet wavelet analysis from 1990:m1 to 2021:m4. The results of the analysis provide empirical evidence for the dynamics of the relationship between ethanol production and corn prices in the short and long term. However, the striking output of this paper is that increases in corn prices have followed increases in fuel ethanol production in the US markets since 2010. Especially in the long-term (from 2010:m3 to 2019:m12), the increase in ethanol production caused an increase in corn prices. From a sustainable development perspective, this paper points to the existence of a conflict between ethanol production and corn prices in the US over the past decade.

The ability of Pichia kudriavzevii to tolerate multiple stresses makes it promising for developing improved bioethanol production processes.

Thermotolerant ethanol fermenting yeasts have been extensively used in industrial bioethanol production. However, little is known about yeast physiology under stress during bioethanol processing. This study investigated the physiological characteristics of the thermotolerant yeast Pichia kudriavzevii, strains NUNS-4, NUNS-5 and NUNS-6, under the multiple stresses of heat, ethanol and sodium chloride. Results showed that NUNS-4, NUNS-5 and NUNS-6 displayed higher growth rates under each stress condition than the reference strain, Saccharomyces cerevisiae TISTR5606. Maximum specific growth rates under stresses of heat (45°C), 15% v/v ethanol and 1·0 M sodium chloride were 0·23 ± 0·04 (NUNS-4), 0·11 ± 0·01 (NUNS-5) and 0·15 ± 0·01 h-1 (NUNS-5), respectively. Morphological features of all yeast studied changed distinctly with the production of granules and vacuoles when exposed to ethanol, and cells were elongated under increased sodium chloride concentration. This study suggests that the three P. kudriavzevii strains are potential candidates to use in industrial-scale fermentation due to a high specific growth rate under multiple stress conditions. Multiple stress-tolerant P. kudriavzevii NUNS strains have received much attention not only for improving large-scale fuel ethanol production, but also for utilizing these strains in other biotechnological industries.

Life cycle assessment and techno-economic analysis of fuel ethanol production via bio-oil fermentation based on a centralized-distribution model

Fuel ethanol from biomass resources has been gaining attention. Fuel ethanol production via a regional bio-oil production and a central bio-oil direct or indirect fermentation appears interesting and innovative. Techno-economic-environmental analysis is used to evaluate the economic feasibility and environmental impacts of this production process at the industrial scale. The rigorous process models for the fuel ethanol production via bio-oil fermentation are developed using R software. The internal rates of return and the minimum selling price are estimated based on techno-economic analysis; global warming potential 100a, cumulative energy demand, and eco-indicator 99 methods are used using three allocation methods based on life cycle assessment. A sensitivity analysis and an uncertain analysis of the techno-economic-environmental indicators are also conducted. For the direct and indirect fermentation pathway, the internal rates of return is separately 25.6% and 41.5%, and the minimum selling price is $218/metric ton ethanol ($0.98/gge) and $264/metric ton ethanol ($1.19/gge), respectively. According to economic value-based allocation methods, the life cycle assessment indicates the global warming potential (GWP100a) of the production of 1 kg of ethanol via the bio-oil direct fermentation pathway and the bio-oil indirect fermentation pathway is 0.729 kg CO2-eq/kg ethanol and 0.718 CO2-eq/kg ethanol, respectively. The calculation and analysis results show that fuel ethanol production by the indirect bio-oil fermentation pathway is more economically feasible and environmentally friendly and could be attractive to capital markets.

Comprehensive Review on Potential Contamination in Fuel Ethanol Production with Proposed Specific Guideline Criteria

Ethanol is a promising biofuel that can replace fossil fuel, mitigate greenhouse gas (GHG) emissions, and represent a renewable building block for biochemical production. Ethanol can be produced from various feedstocks. First-generation ethanol is mainly produced from sugar- and starch-containing feedstocks. For second-generation ethanol, lignocellulosic biomass is used as a feedstock. Typically, ethanol production contains four major steps, including the conversion of feedstock, fermentation, ethanol recovery, and ethanol storage. Each feedstock requires different procedures for its conversion to fermentable sugar. Lignocellulosic biomass requires extra pretreatment compared to sugar and starch feedstocks to disrupt the structure and improve enzymatic hydrolysis efficiency. Many pretreatment methods are available such as physical, chemical, physicochemical, and biological methods. However, the greatest concern regarding the pretreatment process is inhibitor formation, which might retard enzymatic hydrolysis and fermentation. The main inhibitors are furan derivatives, aromatic compounds, and organic acids. Actions to minimize the effects of inhibitors, detoxification, changing fermentation strategies, and metabolic engineering can subsequently be conducted. In addition to the inhibitors from pretreatment, chemicals used during the pretreatment and fermentation of byproducts may remain in the final product if they are not removed by ethanol distillation and dehydration. Maintaining the quality of ethanol during storage is another concerning issue. Initial impurities of ethanol being stored and its nature, including hygroscopic, high oxygen and carbon dioxide solubility, influence chemical reactions during the storage period and change ethanol’s characteristics (e.g., water content, ethanol content, acidity, pH, and electrical conductivity). During ethanol storage periods, nitrogen blanketing and corrosion inhibitors can be applied to reduce the quality degradation rate, the selection of which depends on several factors, such as cost and storage duration. This review article sheds light on the techniques of control used in ethanol fuel production, and also includes specific guidelines to control ethanol quality during production and the storage period in order to preserve ethanol production from first-generation to second-generation feedstock. Finally, the understanding of impurity/inhibitor formation and controlled strategies is crucial. These need to be considered when driving higher ethanol blending mandates in the short term, utilizing ethanol as a renewable building block for chemicals, or adopting ethanol as a hydrogen carrier for the long-term future, as has been recommended.

Identifying loci controlling total starch content of leaf in Nicotiana tabacum through genome-wide association study.

Starch is an important primary metabolite in plants, which can provide bioenergy for fuel ethanol production. There are many studies focusing on starch metabolism in Arabidopsis, maize, and rice, but few reports have been made on the starch content of tobacco leaves. Hence, to identify the marker-trait associations and isolate the candidate genes related to starch content of tobacco leaf, the genome-wide association study (GWAS) was performed using a multiparent advanced generation intercross (MAGIC) population consisting of 276 accessions genotyped by a 430K SNP array. In this study, we detected the leaf starch content of tobacco plants cultivated in two places (Zhucheng and Chenzhou), which showed a wide variation of starch content in the population. A total of 28 and 45 significant single-nucleotide polymorphism (SNP) loci associated with leaf starch content were identified by single-locus and multi-locus GWAS models, respectively, and the phenotypic variance explained by these loci varied from 1.80 to - 14.73%. Furthermore, among these quantitative trait loci (QTLs), one SNP, AX-106011713 located on chromosome 19, was detected repeatedly in multiple models and two environments, which was selected for linkage disequilibrium (LD) analysis to obtain the target candidate region. Through gene annotation, haplotype, and gene expression analysis, two candidate genes encoding E3 ubiquitin-protein ligase (Ntab0823160) and fructose-bisphosphate aldolase (Ntab0375050) were obtained. Results showed that the variety carrying the beneficial alleles of the two candidate genes had higher gene expression level and leaf starch content, suggesting the potential role of candidate genes in enhancing the level of tobacco leaf starch content. Furthermore, silencing of Ntab0823160 in tobacco leaves reduced the content of total starch to 39.41-69.75% of that in the wide type plants. Taken together, our results provide useful resources for further investigation of the starch metabolic pathway and are also beneficial for the creation of eco-friendly cultivars with increased accumulation of leaf starch content.

Life cycle assessment and techno-economic analysis of ethanol production via coal and its competitors: A comparative study

The world’s first industrialized coal-based fuel ethanol (CBFE) and emerging second-generation fuel bioethanol (SGFB) routes are promising alternatives and potential competitors to the conventional first-generation fuel bioethanol (FGFB) route. Understanding the comprehensive competitiveness of the three fuel ethanol production routes is important for the development of clean and low-carbon transportation worldwide. However, there is currently a dearth of related knowledge and scientific data. In this study, we identified and compared the strengths and weaknesses of the three fuel ethanol production routes using an assessment framework that integrates life cycle assessment, techno-economic analysis, and entropy weight method. Environmental performance was investigated with the 18 midpoint impact categories of the ReCiPe 2016 method and modeled using the SimaPro software. Economic performance was represented using the net present value, dynamic payback period, and internal rate of return. The results demonstrated the highest comprehensive score in the SGFB route owing to its excellent environmental performance, which will likely address the unsustainability of the FGFB route through the efficient utilization of agricultural residuals. Owing to its considerable economic benefit, the industrialization of the CBFE route not only offers a new downstream chain in the coal industry but also diversifies the sources of fuel ethanol away from biomass. However, such a promising alternative faces a substantial challenge associated with its significant environmental impact, especially with its high greenhouse gas emissions. These results provide valuable information on the relative advantages and disadvantages of the CBFE, FGFB, and SGFB routes for scientific tradeoffs and decisions.

Evaluation of different strains of Saccharomyces cerevisiae for ethanol production from high-amylopectin BRS AG rice (Oryza sativa L.)

Ethanol is the main biofuel produced by fermentation route and the search for new feedstocks to produce fuel ethanol is still a great challenge. This work aims to compare the ethanol production from a new irrigated rice cultivar BRS AG to the conventional cultivar BRS PAMPA applied in Brazil. Six different commercial strains of Saccharomyces cerevisiae (BG-1, CAT-1, FT-858, JP-1, PE-2, and SA-1) were applied in fermentation reactions. Fermentations performed with BRS PAMPA rice revealed that the highest yields were achieved with strain SA-1, corresponding to 93.0% of the theoretical maximum and final ethanol concentration of 58.92 g L−1, and with CAT-1, a yield of 92.7% and final ethanol concentration of 58.93 g L−1. For the fermentations with BRS AG rice, the highest yields were obtained with strain FT-858, exhibiting a 89.6% yield and final ethanol concentration of 62.45 g L−1, and with CAT-1, 87.9% yield and final ethanol concentration of 61.25 g L−1 were achieved. The most appropriate microorganism for ethanol production using BRS PAMPA rice and BRS AG rice was CAT-1. Comparatively, the ethanol yield and productivity using BRS AG were higher than those observed for BRS PAMPA for all strains, except for PE-2 and SA-1 that led to very similar results. The experimental results showed that the giant rice BRS AG is an excellent feedstock for fuel ethanol production in lowland fields.

Paper mulberry fruit juice: a novel biomass resource for bioethanol production

By way of broadening the use of diverse sustainable bioethanol feedstocks, the potentials of Paper mulberry fruit juice (PMFJ), as a non-food, sugar-based substrate, were evaluated for fuel ethanol production. The suitability of PMFJ was proven, as maximum ethanol concentration (56.4 g/L) and yield (0.39 g/g) were achieved within half a day of the start of fermentation, corresponding to very high ethanol productivity of 4.7 g/L/hr. The established potentials were further optimally maximized through the response surface methodology (RSM). At the optimal temperature of 30 °C, yeast concentration of 0.55 g/L, and pH of 5, ethanol concentration, productivity, and yield obtained were 73.69 g/L, 4.61 g/L/hr, and 0.48 g/g, respectively. Under these ideal conditions, diverse metal salts were afterward screened for their effects on PMFJ fermentation. Based on a two-level fractional factorial design, nutrient addition had no positive impact on ethanol production. Thus, under the optimal process conditions, and without any external nutrient supplementation, bioethanol from PMFJ compared favorably with typical sugar-based energy crops, highlighting its resourcefulness as a high-value biomass resource for fuel ethanol production.Graphical