2G Ethanol Research Articles

Physiological comparisons among Spathaspora passalidarum, Spathaspora arborariae, and Scheffersomyces stipitis reveal the bottlenecks for their use in the production of second-generation ethanol.

The microbial conversion of pentoses to ethanol is one of the major drawbacks that limits the complete use of lignocellulosic sugars. In this study, we compared the yeast species Spathaspora arborariae, Spathaspora passalidarum, and Sheffersomyces stipitis regarding their potential use for xylose fermentation. Herein, we evaluated the effects of xylose concentration, presence of glucose, and temperature on ethanol production. The inhibitory effects of furfural, hydroxymethylfurfural (HMF), acetic acid, and ethanol were also determined. The highest ethanol yield (0.44g/g) and productivity (1.02g/L.h) were obtained using Sp. passalidarum grown in 100g/L xylose at 32°C. The rate of xylose consumption was reduced in the presence of glucose for the species tested. Hydroxymethylfurfural did not inhibit the growth of yeasts, whereas furfural extended their lag phase. Acetic acid inhibited the growth and fermentation of all yeasts. Furthermore, we showed that these xylose-fermenting yeasts do not produce ethanol concentrations greater than 4% (v/v), probably due to the inhibitory effects of ethanol on yeast physiology. Our data confirm that among the studied yeasts, Sp. passalidarum is the most promising for xylose fermentation, and the low tolerance to ethanol is an important aspect to be improved to increase its performance for second-generation (2G) ethanol production. Our molecular data showed that this yeast failed to induce the expression of some classical genes involved in ethanol tolerance. These findings suggest that Sp. passalidarum may have not activated a proper response to the stress, impacting its ability to overcome the negative effects of ethanol on the cells.

Metabolic and Evolutionary Engineering of Diploid Yeast for the Production of First- and Second-Generation Ethanol

Despite a growing preference for second-generation (2G) ethanol in industries, its application is severely restricted owing to a major obstacle of developing a suitable yeast strain for fermentation using feedstock biomasses. In this study, a yeast strain, Saccharomyces cerevisiae A31Z, for 2G bioethanol production was developed from an industrial strain, Angel, using metabolic engineering by the incorporation of gene clusters involved in the xylose metabolism combined with adaptive evolution for evolving its anti-inhibitory properties. This strain outcompeted its ancestors in xylose utilization and subsequent ethanol production and manifested higher tolerance against common inhibitors from lignocellulosic hydrolysates, and also it lowered the production of glycerol by-product. Furthermore, A31Z outperformed in ethanol production using industrial hydrolysate from dried distillers grains with solubles and whole corn. Overall, this study provided a promising path for improving 2G bioethanol production in industries using S. cerevisiae.

Synergistic integration of wastewaters from second generation ethanol plant for algal biofuel production: an industrially relevant option.

The present study provides an integrated method for utilizing the wastewaters from second generation (2G) ethanol pretreatment plant for microalgal biomass and lipid production. The study was conducted using a mixture of wastewaters (referred as MW; pH 4.3) generated after washing of acidic and alkaline-soaked lignocellulosic biomass prior to pretreatment process. The growth studies indicated that the thermotolerant strain of Chlorella pyrenoidosa (C. pyrenoidosa) M18 exhibited higher cell proliferation in wastewater as compared to freshwater. About 20-25% enhancement in biomass (509mg L-1 d-1 ± 3.09) and lipid productivity (146mg L-1 d-1 ± 1.34) was observed in MW. The total chlorophyll content and variable fluorescence by maximum fluorescence (Fv/Fm) ratio of strain cultivated in MW were 10.32µgmL-1 and 0.75, respectively. The use of MW also enhanced the content of saturated and monounsaturated fatty acids in total lipid. The exhausted wastewater medium obtained after harvesting the auto-flocculated biomass was also reused up to three successive growth cycles. The recycled medium without any nutrient addition could be used for two subsequent rounds with enhanced biomass (520mg L-1 d-1 ± 4.07) and lipid (157.71mg L-1 d-1 ± 1.09) productivities. This synergistic approach of cultivating thermotolerant microalgae with wastewater from 2G pretreatment plant provides an economical setup for development of commercial algal biofuel technology.

Modeling and simulation of the biosurfactant production by enzymatic route using xylose and oleic acid as reagents

The biosynthesis of sugar esters, molecules with biosurfactant properties, can occur through the esterification of sugars with fatty acids by enzymatic catalysis. An alternative to reduce the impact of raw materials on the final biosurfactant production cost and the reuse of industrial waste is to use residues from vegetable oil industries as a source of free fatty acids, such as oleic acid, and lignocellulosic residues of 2G ethanol as a source of sugar (xylose). In this scenario, the present work aimed at modeling the biosurfactants production via heterogeneous biocatalysis using lipase, oleic acid, and xylose. Product separation and purification were performed using a sequence of precipitations (adding ethanol, water, and methyl ethyl ketone). The simulation was performed using the equation-oriented software EMSO (Environment for Modeling, Simulation, and Optimization), CAPE-OPEN compliant. The percentage of biosurfactants in the product was around 86%, with a recovery of 88% in the purification. Regarding the study of energy expenditure, a value of -604.1 kW of heat associated with cooling and a value of 137.6 kW associated with heating was observed. Developed mathematical models successfully described the process. The initial economic analysis of the process indicates a minimum biosurfactant selling price of US$ 72.37/kg.

Towards a practical industrial 2G ethanol production process based on immobilized recombinant S. cerevisiae: Medium and strain selection for robust integrated fixed-bed reactor operation

The development of a robust and scalable process for 2G ethanol production from renewable feedstock requires high ethanol titers and long-term stability. A strategy based on strain evaluation and integration with 1G ethanol production was used to overcome these challenges. Three engineered superior S. cerevisiae strains were evaluated in industrial media, using either pure sugarcane bagasse hydrolysates or mixed with molasses from sugarcane processing. Cell recycling was limited to 4 batches and decreasing productivity was observed in fermentation media based on concentrated bagasse hydrolysate, even after detoxification. When crude bagasse hydrolysate was mixed with molasses (MBH medium), fermentations with up to 10 cell recycles and final ethanol concentrations over 50 g/L were achieved with all strains. In a fixed-bed reactor operated with the selected MDS130 strain and MBH medium, remarkable ethanol productivities up to 22.8 g/L/h were reached and up to 20 cell recycles were possible.

Catalytic Upgrading of Xylose to Furfuryl Alcohol over Zr-SBA-15

Direct conversion of xylose to furfuryl alcohol was investigated over Zr-SBA-15 mesoporous catalysts. A low-concentration aqueous xylose solution was used as feedstock to fit the conditions that the monosaccharide is released during waste biomass pretreatment for 2G ethanol production. A coupled dehydration-transfer hydrogenation approach was adopted in this study, using 2-propanol as the hydrogen donor in the liquid phase. It was shown that addition of Zr into the SiO2 framework created active surface acid sites for converting xylose to furfuryl alcohol, rendering selectivity of around 45%, and furfural and xylulose as the main coproducts. Activity and product distribution were significantly affected by the proportion of water and 2-propanol in the liquid phase. Both xylose conversion and selectivity to furfuryl alcohol dropped progressively by decreasing the volumetric amount of 2-propanol.

Operational and biochemical aspects of co-digestion (co-AD) from sugarcane vinasse, filter cake, and deacetylation liquor.

This work performed co-AD from the vinasse and filter cake (from 1G ethanol production) and deacetylation liquor (from the pretreatment of sugarcane straw for 2G ethanol production) in a semi-Continuous Stirred Tank Reactor (s-CSTR) aiming to provide optimum operational parameters for continuous CH4 production. Using filter cake as co-substrate may allow the reactor to operate throughout the year, as it is available in the sugarcane off-season, unlike vinasse. A comparison was made from the microbial community of the seed sludge and the reactor sludge when CH4 production stabilized. Lactate, butyrate, and propionate fermentation routes were denoted at the start-up of the s-CSTR, characterizing the acidogenic phase: the oxidation-reduction potential (ORP) values ranged from -800 to -100 mV. Once the methanogenesis was initiated, alkalizing addition was no longer needed as its demand by the microorganisms was supplied by the alkali characteristics of the deacetylation liquor. The gradual increase of the applied organic load rates (OLR) allowed stabilization of the methanogenesis from 3.20 gVS L-1 day-1: the highest CH4 yield (230 mLNCH4 g-1VS) and average organic matter removal efficiency (83% ± 13) was achieved at ORL of 4.16 gVS L-1 day-1. The microbial community changed along with the reactor operation, presenting different metabolic routes mainly due to the used lignocellulosic substrates. Bacteria from the syntrophic acetate oxidation (SAO) process coupled to hydrogenotrophic methanogenesis were predominant (~ 90% Methanoculleus) during the CH4 production stability. The overall results are useful as preliminary drivers in terms of visualizing the co-AD process in a sugarcane biorefinery integrated to scale. KEY POINTS: • Integration of 1G2G sugarcane ethanol biorefinery from co-digestion of its residues. • Biogas production from vinasse, filter cake, and deacetylation liquor in a semi-CSTR. • Lignocellulosic substrates affected the biochemical routes and microbial community. • Biomol confirmed the establishment of the thermophilic community from mesophilic sludge.

Functional properties and potential application of ethanol tolerant β-glucosidases from Pichia ofunaensis and Trichosporon multisporum yeasts.

β-Glucosidases have been extensively investigated to integrate the enzyme complex for cellulose fiber saccharification and for improving the aroma of wine. To produce these enzymes, greater attention has been given to filamentous fungi and bacteria, and few investigations have targeted the potential applications of enzymes secreted by yeasts. Addressing this issue, in this study, β-glucosidases were produced by the Pichia ofunaensis and Trichosporon multisporum yeasts, via solid state fermentation with wheat bran as a substrate. When using p-Nitrophenyl β-d-glucopyranoside (pNPG) as an enzyme substrate, maximum β-glucosidase activities were detected at pH 5.5-6.0 and 50-60°C for P. ofunaensis, and pH 5-6 and 55°C for T. multisporum. Both enzymes were able to hydrolyze cellobiose and exhibited stability over a wide range of pH (3.5-9.0) for 24h at 4°C, thermostability up to 50°C for 1h and tolerance to 10mM phenolic compounds. Negative modulation on enzyme activity was observed in the presence of Cu2+, Fe3+, Zn2+, Al3+ and Hg2+, while both β-glucosidases were tolerant to 30% methanol, isopropanol and acetone. In the presence of ethanol and glucose, enzymes from P. ofunaensis were the more active and stable of the two. These enzymes, especially the P. ofunaensis β-glucosidases, could be tested in enology for improving the aroma of wine and for integrating a cellulolytic complex to produce 2G ethanol.

Towards Comparable Carbon Credits: Harmonization of LCA Models of Cellulosic Biofuels

Decarbonization programs are being proposed worldwide to reduce greenhouse gas (GHG) emissions from transportation fuels, using Life Cycle Assessment (LCA) models or tools. Although such models are broadly accepted, varying results are often observed. This study describes similarities and differences of key decarbonization programs and their GHG calculators and compares established LCA models for assessing 2G ethanol from lignocellulosic feedstock. The selected LCA models were GHGenius, GREET, JRC’s model, and VSB, which originated calculators for British Columbia’s Low Carbon Fuel Standard, California’s Low Carbon Fuel Standard, Renewable Energy Directive, and RenovaBio, respectively. We performed a harmonization of the selected models by inserting data of one model into other ones to illustrate the possibility of obtaining similar results after a few harmonization steps and to determine which parameters have higher contribution to closing the gap between default results. Differences among 2G ethanol from wheat straw were limited to 0.1 gCO2eq. MJ−1, and discrepancies in emissions decreased by 95% and 78% for corn stover and forest residues, respectively. Better understanding of structure, calculation procedures, parameters, and methodological assumptions among the LCA models is a first step towards an improved harmonization that will allow a globally accepted and exchangeable carbon credit system to be created.

Lignin Biorefinery: New Horizons in Catalytic Hydrodeoxygenation for the Production of Chemicals

Lignin is a byproduct of the paper mill and second-generation (2G) ethanol biorefinery and the largest naturally available source of aromatic building blocks. It can serve as a feedstock to produce...

Conversion of pilot plant derived 2G ethanol cellulosic stillage to value-added chemicals

For second-generation (2 G) cellulosic ethanol production to be sustainable and viable, there is the need to value-add to the stillage. Here, pilot plant-derived 2G ethanol sugarcane bagasse stillage (BS) and eucalyptus stillage (ES) was transformed into valuable products using hydrothermal liquefaction (HTL) at 300 °C and 20 bar with Pd/C and K2CO3. BS produced oil, phenolic monomers, and organic acid yields of 32 %, 49 % and 25 % respectively, while yields for ES were lower. Catechol constituted 43 % of the total phenolic content for BS. Recycling the aqueous phase (containing acetic, formic, lactic, and propionic acids) improved phenol, guaiacol and catechol yields. Oil stability tests indicated a significant drop in oil yield with aging, but there was no significant change in higher heating value. A preliminary techno-economic analysis suggests that the potential value of producing 2G ethanol and products (including fertilizer) from BS is three times that of depithed sugarcane bagasse. This study demonstrated a potential technology to convert 2 G cellulosic ethanol stillage to value-added chemicals, which not only improved the efficiency and profitability of 2G ethanol production but reduced organic contaminants synthesis.

Immobilization of Spathaspora passalidarum NRRL Y-27907 in Calcium Alginate Aiming the Production of Second-Generation Ethanol

The immobilization of S. passalidarum in calcium alginate beads for second-generation ethanol production (2G ethanol) was evaluated in a medium that simulated a hemicellulosic hydrolysate of sugarcane bagasse pretreated with diluted sulfuric acid in terms of sugar composition. Three sets of sequential batch fermentations (SBF) were carried out with free cells or immobilized cells in high (HSC) and moderate (MSC) initial sugar concentration (120 and 70 g/L, respectively). SBF were characterized by five consecutive batches performed in shaker, at 30 °C and 110 rpm. Better results were observed for the SBF with immobilized cells in MSC medium when compared to HSC (Y’P/S of 0.27 ± 0.02 and 0.19 ± 0.03 g/g, respectively), in the second batch cycle. The value for YP/S in MSC was similar to the obtained with free cells (0.30 ± 0.02 to 0.33 ± 0.02 g/g). However, QP was lower for MSC with immobilized cells, reaching 0.81 ± 0.04 g/L.h in the second batch, while for free cells the QP varied from 1.06 ± 0.02 to 1.16 ± 0.22 g/L.h. A technique for determining the concentration of immobilized cells in the alginate beads was applied, which made it possible to determine the specific rates for the SBF performed. According to the results obtained, it was possible to demonstrate that S. passalidarum can be immobilized in calcium alginate and reused through SBF, with performance similar to free cells, which can be a good strategy for fermentation of hemicellulosic hydrolysates.

Sustainable Second-Generation Ethanol Production from Switchgrass Biomass via Co-fermentation of Pentoses and Hexoses Using Novel Wild Yeasts

The production of second-generation (2G) ethanol remains an interesting proposition for the implementation of sustainable and net carbon–neutral energy systems. To be economically viable, 2G biorefineries must make use of all processing streams, including the less desirable pentose (C5) sugar stream. In this work, a strategy of sequential dilute acid and alkaline pretreatment of the lignocellulosic feedstock, switchgrass, was implemented for improving the fermentable sugar yield. The hemicellulose-enriched hydrolysate obtained after dilute acid pretreatment was fermented by a newly isolated wild Scheffersomyces parashehatae strain—UFMG-HM-60.1b; the corresponding ethanol yield (YPS) and volumetric productivity (QP) were 0.19 g/g and 0.16 g/L h, respectively. The remaining switchgrass cellulignin fraction was subjected to optimized alkaline delignification at 152 ºC for 30 min. Then, the delignified solid fraction was subjected to contiguous enzymatic saccharification and fermentation releasing a glucose (C6) sugar stream. The control yeast strain, Saccharomyces cerevisiae 174, displayed an ethanol YPS of 0.46 g/g and QP of 0.70 g/L h for the C6 sugar stream, whereas the above-mentioned wild strain presented YPS and QP of 0.29 g/g and 0.38 g/L h, respectively. Upon combining the conversion of hemicellulose (37%) and cellulose-derived sugars (57%), the wild S. parashehatae strain provided higher yield (94%) than the generic S. cerevisiae (90%). Henceforth, our sequential two-stage pretreatment and fermentation of C5 and C6 sugar streams provides a pathway for maximum utilization of switchgrass carbohydrates for 2G ethanol production.

Structural features of protic ionic liquids and their impact on pretreatment performance for 2G ethanol production

Biomass pretreatment with protic ionic liquids (PILs) is a promising source of renewable energy and bioproducts, in which different cation/anion combinations may present different behavior towards biomass modification such as selective lignin and/or carbohydrate solubilization. The potential of 20 PILs as pretreatment agents was investigated, whose cations presented two different functional groups and different carbon chain lengths. The best solvent in terms of lignin solubilization during pretreatment was obtained by cations with a functional group (-OH and –NH2). High cellulose conversion was obtained with ethanolamine and ethylenediamine monoacetate ([2He][Ac] and [Etid][Ac]), under different pretreatment conditions (175 °C and 140 °C for 2 h, respectively). The presence of an alkaline anion and a functionalized cation enhanced the pretreatment effectiveness. The results presented in this work will be useful to design novel protic ionic liquids for pretreatment applications in biofuel processes, which can also be integrated to produce bioproducts within the biorefinery concept.

Yeast immobilization systems for second‐generation ethanol production: actual trends and future perspectives

AbstractYeast immobilization with low‐cost carrier materials is a suitable strategy to optimize the fermentation of lignocellulosic hydrolysates for the production of second‐generation (2G) ethanol. It is defined as the physical confinement of intact cells to a certain region of space (the carrier) with the preservation of their biological activity. This technological approach facilitates promising strategies for second‐generation bioethanol production due to the enhancement of the fermentation performance that is expected to be achieved. Using immobilized cells, the resistance to inhibitors contained in the hydrolysates and the co‐utilization of sugars are improved, along with facilitating separation operations and the reuse of yeast in new production cycles. Until now, the most common immobilization technology used calcium alginate as a yeast carrier but other supports such as biochar or multispecies biofilm membranes have emerged as interesting alternatives. This review compiles updated information about cell carriers and yeast‐cell requirements for immobilization, and the benefits and drawbacks of different immobilization systems for second‐generation bioethanol production are investigated and compared.

Production of first- and second-generation ethanol for use in alcohol-based hand sanitizers and disinfectants in India.

Emergence of “severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)” causing “COVID-19” or “coronavirus disease 19” as pandemic has got worldwide attention towards hygiene as the first line of defense for the infection control. It is first line of defense not only from COVID-19 but also from other infectious diseases caused by deadly pathogens such as cholera, hepatitis, tuberculosis, polio, etc. Absence of any particular vaccine or treatment let World Health Organization (WHO) recommend to the public to maintain social distancing along with regularly washing their hands with soap, sanitize their hands (where washing is not possible), and disinfect their belongings and buildings to avoid the infection. Out of various formulations available in the market, WHO has recommended alcohol-based hand sanitizers, which mainly comprise of ethanol, isopropyl alcohols, and hydrogen peroxides in different combinations due to their high potential to kill the broad range of pathogens including bacterial, viral, fungal, helminthes, etc. Therefore, alcohol-based sanitizers are in high demand since centuries to prevent infection from pathogenic diseases. Ethanol is the most common and popular alcohol in terms of vanishing wide range of pathogens, convenient to use and its production. Ethanol is produced worldwide and is used in various sectors, e.g., beauty and cosmetics, food and beverages, and as the most demanding gasoline additive. The present review is focused on the ethanol production in India, its diversified applications emphasizing hand sanitizers with discussions on formulation of sanitizer and disinfectants, and viability of lignocellulosic and food grain–based ethanol. The review article also emphasizes on the technological details of 1G and 2G ethanol production, their associated challenges, and inputs for the improved ethanol yields so as to strengthen the supply chain of ethanol in India, and making “Atmanirbhar Bharat” (Self-reliant India) campaign of Indian government successfully viable.

The water consumption of sugarcane bagasse post-washing after protic ionic liquid pretreatment and its impact on 2G ethanol production

Despite the water consumption of the first-generation ethanol (1G) production from sugarcane being widely studied, there are only a few experimental studies on water consumption — especially in the pulp washing — in second generation (2G) ethanol production. A quantitative evaluation of water wash consumption in the pretreatment with the protic ionic liquid (PIL) monoethanolammonium acetate [MEA][OAc] has shown that a water consumption between 600−1,000 wt% for two temperatures, 25 and 80 °C, decreased overall enzyme performance in saccharification compared to the full wash sample. The best condition in terms of high yield and low water consumption was found to be 800 wt%/80 °C, with up to 83 and 61.8 % of glucose and xylose yields against 97.9 and 85 % for the full wash sample. However, despite the full wash still presenting a superior ethanol yield, 87.4 %, the best condition with limited amount of water, 800 wt%/80 °C, also had a high ethanol yield of 86.1 %. Mass balance calculations confirmed that optimized [MEA][OAc] pretreatment with 800 wt%/80 °C and full wash conditions provided the highest ethanol yield per ton of biomass amongst several types of PIL and non-PIL pretreatments, 299 and 379 L 2G ethanol per ton of biomass, with an estimated water consumption of 56 and 647 ton, paving the way for an effective and more water-sustainable pretreatment technology for 2G ethanol production.

Diversifying the portfolio of sugarcane biorefineries: Anaerobic digestion as the core process for enhanced resource recovery

The continuous search to combine clean energy supply with the efficient exploitation of bioenergy sources is one of the most recurring efforts to meet global energy demands on an environmentally friendly basis. Sugarcane biorefineries play a central role in this context by providing sugar, ethanol and bioelectricity. However, the high energy required in ethanol production limits resource recovery efficiency in conventional sugarcane processing, motivating the investigation of approaches that maximize energetic gains. This study proposes the application of anaerobic digestion (AD) as the core processing step in sugarcane biorefineries, providing performance data for the biomethanation of juice, molasses and vinasses from different sources, namely, first generation (1G; annexed and autonomous) and second generation (2G) ethanol production. A detailed scenarization-based assessment was also carried out, comparing the proposed AD-based schemes with conventional production chains. Relatively similar performances were obtained in the experimental step, irrespective of the compositional differences of the substrates. However, the energetic potential of juice- and molasses-based methane production was at least 2-fold higher than the ones of all types of vinasses (282.81–627.84 vs. 57.10–131.52 MJ TC−1). Scenario comparison indicated the production of biogas and sugar as the most efficient energetic exploitation (94.4%) of sugars from sugarcane. Finally, the energy returned on energy invested ratio estimated for biogas-derived electricity exceeded that of ethanol production by 400%. Thus, AD-based biorefineries have great potential to meet the energy efficiency criteria of sustainable development goals in the coming decades.

Brazilian biorefineries from second generation biomass: critical insights from industry and future perspectives

AbstractTransitioning from gasoline and petroleum‐based products to biofuels and green chemicals is a paradigm shift that will lead to the development of the bioeconomy. In this sense, the role of biorefineries in countries like Brazil is very important as the country generates a huge amount of second generation (2G) biomass every year and also has an attractive consumable market. However, technological innovations are still required to unleash the fullest potential of biomass conversion to biofuels and biochemicals, although successful examples are already a reality. For example, Amyris Inc. has developed renewable products for cosmetics (squalene), healthcare (artemisinin), and flavors / fragrances, and Suzano Papel e Celulose has developed sustainable technologies for the production of pulp and paper, and lignin‐derived adhesives (Ecolig). First‐generation ethanol in Brazil is an established source of transportation fuel but 2G ethanol production with low production costs is still a challenge at commercial scale, and companies like Raízen and GranBio continue making efforts to improve the economic feasibility of the adopted processes. In this context, the RenovaBio Policy launched by the Federal Brazilian Government in December 2017 aims to boost the production and utilization of biofuels and green chemicals in the country. Considering the matters mentioned above, this paper discusses the Brazilian biorefinery developments, technological advances, and current industrial scenario for the production of biofuels and chemicals. © 2021 Society of Industrial Chemistry and John Wiley & Sons Ltd.

Understanding the differences in 2G ethanol fermentative scales through omics data integration.

In this work, we evaluated the fermentative performance and metabolism modifications of a second generation (2G) industrial yeast by comparing an industrial condition during laboratory and industrial scale fermentations. Fermentations were done using industrial lignocellulosic hydrolysate and a synthetic medium containing inhibitors and analyses were carried out through transcriptomics and proteomics of these experimental conditions. We found that fermentation profiles were very similar, but there was an increase in xylose consumption rate during fermentations using synthetic medium when compared to lignocellulosic hydrolysate, likely due to the presence of unknown growth inhibitors contained in the hydrolysate. We also evaluated the bacterial community composition of the industrial fermentation setting and found that the presence of homofermentative and heterofermentative bacteria did not significantly change the performance of yeast fermentation. In parallel, temporal differentially expressed genes (tDEG) showed differences in gene expression profiles between compared conditions, including heat shocks and the presence of up-regulated genes from the TCA cycle during anaerobic xylose fermentation. Thus, we indicate HMF as a possible electron acceptor in this rapid respiratory process performed by yeast, in addition to demonstrating the importance of culture medium for the performance of yeast within industrial fermentation processes, highlighting the uniquenesses according to scales.