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Economically feasible ethanol production requires efficient hydrolysis of lignocellulosic biomass and high–temperature processing to enable simultaneous saccharification and fermentation. During the lignocellulolysic hydrolysate, the yeast must encounter with a multiple of inhibitors such as heat and furfural. To solve this problem, a potential fermentative yeast strain that tolerated simultaneous multistress and enhance ethanol concentration was investigated. Twenty yeast isolates were classified into two major yeast species, namely Pichia kudriavzevii (twelve isolates) and Candida tropicalis (eight isolates). All P. kudriavzevii isolates were able to grow at high temperature (45 °C) and exhibited stress tolerance toward furfural. Among P. kudriavzevii isolates, NUCG–S3 presented the highest specific growth rate under each stress condition of heat and furfural, and multistress. Morphological changes in P. kudriavzevii isolates (NUCG–S2, NUCG–S3, NUKL–P1, NUKL–P3, and NUOR–J1) showed alteration in mean cell length and width compared to the non–stress condition. Ethanol production by glucose was also determined. The yeast strain, NUCG–S3, gave the highest ethanol concentrations at 99.46 ± 0.82, 62.23 ± 0.96, and 65.80 ± 0.62 g/l (P < 0.05) under temperature of 30 °C, 40 °C, and 42 °C, respectively. The tolerant isolated yeast NUCG–S3 achieved ethanol production of 53.58 ± 3.36 and 48.06 ± 3.31 g/l (P < 0.05) in the presence of 15 mM furfural and multistress (42 °C with 15 mM furfural), respectively. Based on the results of the present study, the novel thermos and furfural-tolerant yeast strain P. kudriavzevii NUCG–S3 showed promise as a highly proficient yeast for high–temperature ethanol fermentation. [ABSTRACT FROM AUTHOR]

Kluyveromyces markus CGMCC13907 and Saccharomyces cerevisiae AS2. 119 were selected as mixed starter cultures for fermentation of whey liquid to produce whey vinegar. Plackett-Burman Design (PBD) and Box-Behnken Design (BBD) were used to optimize the ethanol fermentation process. The results showed that the optimal ethanol fermentation process was K. markus CGMCC13907 inoculum volume 4. 0×106 CFU/mL, S. cerevisiae AS2. 119 inoculum volume 4. 5×106 CFU/ mL, fermentation time 151 h, fermentation temperature 40. 0 ×, fermentation pH value 5. 6, ginger powder dosage 0. 09 g/100 mL. Under this condition, the concentration of ethanol in fermentation liquid reached 8. 70 %vol, which increased by 56. 2% compared with that before optimization. K. markus CGMCC13907 combined with S. cerevisiae AS2. 119 could effectively solve the lactose fermentation problem in the process of making vinegar from whey, and achieve a better ethanol concentration. [ABSTRACT FROM AUTHOR]

AbstractGlobal energy demand is experiencing a notable surge due to growing energy security. Renewable energy sources, like ethanol, are becoming more viable. In the present study, the application of a PSO-PID (Particle Swarm Optimization – Proportional Integral Derivative) controller with a split-range control strategy was suggested for the regulation of temperature within the fermentation system. To optimize performance, a POS-PID controller with a split-range arrangement utilizing two control valves for hot and cold utilities was constructed. The study began by examining the open-loop dynamic response of the system to inlet temperature and concentration disturbances during ethanol production fermentation. Subsequently, a transfer function model was developed through linearization at the steady-state operating point. The split-range controller structure, implemented by optimizing the PSO-PID controller parameters using PSO, effectively demonstrated temperature control in simulations of a nonlinear model. In this investigation, the ethanol fermentation system was modeled as a CSTR using a modified Monod equation for microbial growth kinetics. Various dynamic behavioral disturbances were explored and verified in the model with plant data in this study. The simulation model results were validated through plant data. The proposed method showed superior closed-loop performance with respect to errors, with the actuators proving to be effective than other reported methods for temperature control. [ABSTRACT FROM AUTHOR]

Thermophilic actinomycetes are commonly found in extreme environments and can thrive and adapt to extreme conditions. These organisms exhibit substantial variation and garnered significant interest due to their remarkable enzymatic activities. This study evaluated the potential of Streptomyces griseorubens NBR14 and Nocardiopsis synnemataformans NBRM9 strains to produce thermo-stable amylase via submerged fermentation using wheat and bean straw. The Box-Behnken design was utilized to determine the optimum parameters for amylase biosynthesis. Subsequently, amylase underwent partial purification and characterization. Furthermore, the obtained hydrolysate was applied for ethanol fermentation using Saccharomyces cerevisiae. The optimal parameters for obtaining the highest amylase activity by NBR14 (7.72 U/mL) and NBRM9 (26.54 U/mL) strains were found to be 40 and 30 °C, pH values of 7, incubation time of 7 days, and substrate concentration (3 and 2 g/100 mL), respectively. The NBR14 and NBRM9 amylase were partially purified, resulting in specific activities of 251.15 and 144.84 U/mg, as well as purification factors of 3.91 and 2.69-fold, respectively. After partial purification, the amylase extracted from NBR14 and NBRM9 showed the highest activity level at pH values of 9 and 7 and temperatures of 50 and 60 °C, respectively. The findings also indicated that the maximum velocity (Vmax) for NBR14 and NBRM9 amylase were 57.80 and 59.88 U/mL, respectively, with Km constants of 1.39 and 1.479 mM. After 48 h, bioethanol was produced at concentrations of 5.95 mg/mL and 9.29 mg/mL from hydrolyzed wheat and bean straw, respectively, through fermentation with S. cerevisiae. Thermophilic actinomycetes and their α-amylase yield demonstrated promising potential for sustainable bio-ethanol production from agro-byproducts. [ABSTRACT FROM AUTHOR]

The study aims to enhance ethanol production by Wickerhamomyces subpelliculosus ZE75 isolated from marine sediment. In addition, analyzing the kinetic parameters of ethanol production and optimization of the fermentation conditions was performed. The marine yeast isolate ZE75 was selected as the front runner ethanol-producer, with an ethanol yield of 89.77 gL−1. ZE75 was identified relying on the phenotypic and genotypic characteristics of W. subpelliculosus. The genotypic characterization based on the Internal Transcribed Spacer (ITS) sequence was deposited in the GenBank database with the accession number OP715873. The maximum specific ethanol production rate (vmax) was 0.482 gg−1 h−1 at 175 gL−1 glucose concentration, with a high accuracy of R2 0.95. The maximum growth specific rates (μmax) were 0.141 h−1 obtained at 150 gL−1 glucose concentration with R2 0.91. Optimization of the fermentation parameters such as pH and salinity has been achieved. The highest ethanol yield 0.5637 gg−1 was achieved in a 100% natural seawater-based medium. The maximum ethanol production of 104.04 gL−1 was achieved at pH 4.5 with a specific ethanol rate of 0.1669 gg−1 h−1. The findings of the present study recommend the possibility of ethanol production from a seawater-based medium on a large scale using W. subpelliculosus ZE75. [ABSTRACT FROM AUTHOR]

Background: Production of cheese whey in the EU exceeded 55 million tons in 2022, resulting in lactose-rich effluents that pose significant environmental challenges. To address this issue, the present study investigated cheese-whey treatment via membrane filtration and the utilization of its components as fermentation feedstock. A simulation model was developed for an industrial-scale facility located in Italy's Apulia region, designed to process 539 m3/day of untreated cheese-whey. The model integrated experimental data from ethanolic fermentation using a selected strain of Kluyveromyces marxianus in lactose-supplemented media, along with relevant published data. Results: The simulation was divided into three different sections. The first section focused on cheese-whey pretreatment through membrane filtration, enabling the recovery of 56%w/w whey protein concentrate, process water recirculation, and lactose concentration. In the second section, the recovered lactose was directed towards fermentation and downstream anhydrous ethanol production. The third section encompassed anaerobic digestion of organic residue, sludge handling, and combined heat and power production. Moreover, three different scenarios were produced based on ethanol yield on lactose (YE/L), biomass yield on lactose, and final lactose concentration in the medium. A techno-economic assessment based on the collected data was performed as well as a sensitivity analysis focused on economic parameters, encompassing considerations on cheese-whey by assessing its economical impact as a credit for the simulated facility, dictated by a gate fee, or as a cost by considering it a raw material. The techno-economic analysis revealed different minimum ethanol selling prices across the three scenarios. The best performance was obtained in the scenario presenting a YE/L = 0.45 g/g, with a minimum selling price of 1.43 €/kg. Finally, sensitivity analysis highlighted the model's dependence on the price or credit associated with cheese-whey handling. Conclusions: This work highlighted the importance of policy implementation in this kind of study, demonstrating how a gate fee approach applied to cheese-whey procurement positively impacted the final minimum selling price for ethanol across all scenarios. Additionally, considerations should be made about the implementation of the simulated process as a plug-in addition in to existing processes dealing with dairy products or handling multiple biomasses to produce ethanol. [ABSTRACT FROM AUTHOR]

In this article, the problem of real‐time estimation of the fermentative ethanol process is tackled. The considered observer is a model‐based technique that is robust regarding the model parameter uncertainties and inline noisy measurements. An unstructured kinetic model was used to describe the production of ethanol in a batch bioreactor for Saccharomyces cerevisiae. The biomass concentration was selected as the measured bioreactor´s output via an inline device, where the estimate variables were the substrate and ethanol concentrations. An experimental prototype was constructed to demonstrate the observer's real‐time performance. The experimental results show that the robust, smooth sliding mode observer performs better than the standard proportional sliding mode observer. [ABSTRACT FROM AUTHOR]

[Display omitted] • Raman spectroscopy and chemometrics track metabolic changes in individual yeast cells. • Yeast cells exhibit 3 stages during high gravity ethanol fermentation. • Unique protein structure and increased triacylglycerol synthesis as a defense from ethanol stress. Saccharomyces cerevisiae is the most common microbe used for the industrial production of bioethanol, and it encounters various stresses that inhibit cell growth and metabolism during fermentation. However, little is currently known about the physiological changes that occur in individual yeast cells during ethanol fermentation. Therefore, in this work, Raman spectroscopy and chemometric techniques were employed to monitor the metabolic changes of individual yeast cells at distinct stages during high gravity ethanol fermentation. Raman tweezers was used to acquire the Raman spectra of individual yeast cells. Multivariate curve resolution-alternating least squares (MCR-ALS) and principal component analysis were employed to analyze the Raman spectra dataset. MCR-ALS extracted the spectra of proteins, phospholipids, and triacylglycerols and their relative contents in individual cells. Changes in intracellular biomolecules showed that yeast cells undergo three distinct physiological stages during fermentation. In addition, heterogeneity among yeast cells significantly increased in the late fermentation period, and different yeast cells may respond to ethanol stress via different mechanisms. Our findings suggest that the combination of Raman tweezers and chemometrics approaches allows for characterizing the dynamics of molecular components within individual cells. This approach can serve as a valuable tool in investigating the resistance mechanism and metabolic heterogeneity of yeast cells during ethanol fermentation. [ABSTRACT FROM AUTHOR]

• SCF as a kind of periodic operation is analyzed for its superiority over the steady-state counterpart. • SCF as a kind of impulsive control is evaluated for possible repetition property in long-term operation. • Optimal on-off operation strategies are formulated with guaranteed periodic stability and superiority. Fuel ethanol is highlighted for being renewable and carbon neutral, but a multi-scale challenge exists that hampers its role as a future energy substitute, and with the breakthrough of cellulose pretreatment and enzyme hydrolysis technology, fermentation itself has become one of the main limiting factors for process enhancement. To tackle the problem, this paper studies periodic operation strategies to improve process performance and avoid possible instabilities. Firstly, superiority by periodic operation over the corresponding steady-state operation is verified. Then, to settle the problem of possible instabilities under impulsive control, stability of state-impulsive control is conducted and for the studied case, any self-cycling fermentation starts from batch mode with 50 % discharge-and-refill portion exhibits superior repeatability property, which allows continuous fermentation to operate under very slow overall dilution rate to cope with the extreme slow fermentation rate. Finally, on-off operation problem is formulated that is governed by a multidimensional nonlinear system, affine to the manipulated variable that is under the isoperimetric constraint; with the use of Pontryagin maximum principle, the optimal synthesis of the optimal strategies under integral constraint is computed out, and a practically plausible on-off operation strategy for ethanol fermentation is formulated with guaranteed periodic stability and optimality. [ABSTRACT FROM AUTHOR]

• Thermally self-sufficient heat pump-assisted dividing-wall column for biofuel recovery. • Eco-efficient product recovery after isopropanol – butanol – ethanol (IBE) fermentation. • Cost-effective (0.126 $/kgIBE) and energy-efficient (0.673 kWeh/kgIBE) downstream processing. • Heat pumping and heat integration for electrification of industrial biotechnology. • Large-scale downstream process for sustainable industrial biofuels production. Isopropanol-butanol-ethanol (IBE) fermentation is a superior biofuel production technology as compared to acetone-butanol-ethanol (ABE) fermentation due to the better fuel properties of the obtained products. However, low product concentrations, thermodynamic constraints and the presence of microorganisms lead to complex downstream processing that limits the competitiveness of this biofuel production method. Thus, this original research proposes a novel thermally self-sufficient and eco-efficient downstream process for industrial-scale recovery after IBE fermentation (74 ktonne/y capacity), from a highly dilute broth (>97 wt% water). Gas stripping and heat pump-assisted vacuum evaporation were implemented to separate valuable products from most of the broth. Furthermore, an advanced highly integrated heat pump-assisted azeotropic dividing-wall column was designed to recover high-purity (99 wt%) butanol biofuel and isopropanol – ethanol fuel supplement (89 wt%). The proposed purification process recovers over 99 % of biofuel products in a cost-effective (0.130 $/kg IBE) and energy-efficient way (0.673 kW e h/kg IBE) while allowing full recycle of biomass and most of the separated water. Besides improving yield by continuously recovering the inhibitory products, fermentation can be further enhanced by avoiding biomass loss and reducing water requirements. Lastly, the implemented energy-saving techniques ensure complete electrification of the proposed IBE recovery process. Therefore, the original results of this research study significantly contribute to the development of sustainable biofuel production processes. [Display omitted] [ABSTRACT FROM AUTHOR]

Waterlogging stress is one of the major abiotic stresses affecting the productivity and quality of many crops worldwide. However, the mechanisms of waterlogging tolerance are still elusive in barley. In this study, we identify key differentially expressed genes (DEGs) and differential metabolites (DM) that mediate distinct waterlogging tolerance strategies in leaf and root of two barley varieties with contrasting waterlogging tolerance under different waterlogging treatments. Transcriptome profiling revealed that the response of roots was more distinct than that of leaves in both varieties, in which the number of downregulated genes in roots was 7.41-fold higher than that in leaves of waterlogging sensitive variety after 72 h of waterlogging stress. We also found the number of waterlogging stress-induced upregulated DEGs in the waterlogging tolerant variety was higher than that of the waterlogging sensitive variety in both leaves and roots in 1 h and 72 h treatment. This suggested the waterlogging tolerant variety may respond more quickly to waterlogging stress. Meanwhile, phenylpropanoid biosynthesis pathway was identified to play critical roles in waterlogging tolerant variety by improving cell wall biogenesis and peroxidase activity through DEGs such as Peroxidase (PERs) and Cinnamoyl-CoA reductases (CCRs) to improve resistance to waterlogging. Based on metabolomic and transcriptomic analysis, we found the waterlogging tolerant variety can better alleviate the energy deficiency via higher sugar content, reduced lactate accumulation, and improved ethanol fermentation activity compared to the waterlogging sensitive variety. In summary, our results provide waterlogging tolerance strategies in barley to guide the development of elite genetic resources towards waterlogging-tolerant crop varieties. [ABSTRACT FROM AUTHOR]

The scarcity of essential minerals in the wort used for bioethanol production has long been a persistent concern in industrial processes. This scarcity can negatively impact various aspects of production, including yeast cell vitality and sugar-to-ethanol conversion. In this study, we assessed the nutritional profile of key components of the industrial bioethanol production process and identified nitrogen, phosphorus, magnesium, manganese, zinc, and copper ions deficiencies. Supplementation of fermentation assays with TMNitrofós was carried out until reaching the maximum allowed for manganese (24.5%), zinc (49.4%), and copper (8.8%). Laboratory-scale fermentation assays were conducted under varying conditions of soluble solids in the wort (20, 24, and 26°Brix). These experiments aimed to assess the primary productivity parameters in response to the application of TMNitrofós. Results showed that fermentations using wort with 24 and 26°Brix supplemented with TMNitrofós led to 7% higher fermentative efficiency compared to the control group. The supplemented fermentations demonstrated higher levels of cellular vitality (76.6%) compared to the control group (55.3%). Considering a scale-up in the bioethanol production process with TMNitrofós supplementation, an increase of 266 m3 of ethanol per month was achieved compared to the control group, resulting in cost savings of R$ 586,879.20. [ABSTRACT FROM AUTHOR]

Background: The use of ionic liquids (ILs) to fractionate lignocelluloses for various bio-based chemicals productions is in the ascendant. On this basis, the protic ILs consisting of triethylammonium hydrogen sulfate ([TEA][HSO4]) possessed great promise due to the low price, low pollution, and high efficiency. In this study, the microwave-assistant [TEA][HSO4] fractionation process was established for corn stover fractionation, so as to facilitate the monomeric sugars production and supported the downstream acetone–butanol–ethanol (ABE) fermentation. Results: The assistance of microwave irradiation could obviously shorten the fractionation period of corn stover. Under the optimized condition (190 W for 3 min), high xylan removal (93.17 ± 0.63%) and delignification rate (72.90 ± 0.81%) were realized. The mechanisms for the promotion effect of the microwave to the protic ILs fractionation process were ascribed to the synergistic effect of the IL and microwaves to the depolymerization of lignocellulose through the ionic conduction, which can be clarified by the characterization of the pulps and the isolated lignin specimens. Downstream valorization of the fractionated pulps into ABE productions was also investigated. The [TEA][HSO4] free corn stover hydrolysate was capable of producing 12.58 g L−1 of ABE from overall 38.20 g L−1 of monomeric sugars without detoxification and additional nutrients supplementation. Conclusions: The assistance of microwave irradiation could significantly promote the corn stover fractionation by [TEA][HSO4]. Mass balance indicated that 8.1 g of ABE and 16.61 g of technical lignin can be generated from 100 g of raw corn stover based on the novel fractionation strategy. [ABSTRACT FROM AUTHOR]

Despite the significant progress in the research, the problem of finding an efficient method for producing bioethanol from renewable lignocellulosic waste materials remains unresolved. Our investigation aimed to assess the efficacy of ethanol production from sugar beet pulp (SBP) utilising various approaches, including pretreatment variations, enzymatic processes, and microbial hydrolysis. Our research involved using the post-cultivation concentrate of T. viride LOCK 0588 grown in the SBP-based medium as a source of enzymes. The SBP hydrolysis process was carried out for 48 h at 50 °C. The quantity of sugar released, up to 61 g dm−3, through the utilisation of this extract proved to be on par with the outcomes achieved by the application of the commercial Cellic Ctec2 preparation. The final yields of the ethanol production with the use of the coculture of S. cerevisiae (Ethanol Red) and Scheffersomyces stipitis LOCK 0047 strain were in the range 5.1 ± 0.11 kg 100 kg−1 ÷ 5.38 ± 0.11 kg 100 kg−1. These results provide a solid basis for improving larger-scale industrial procedures that involve converting SBP into bioethanol using a cost-efficient approach of microbial hydrolysis with T. viride and a blend of pentose and hexose fermenting yeast. [ABSTRACT FROM AUTHOR]

Soft sensors based on deep learning regression models are promising approaches to predict real-time fermentation process quality measurements. However, experimental datasets are generally sparse and may contain outliers or corrupted data. This leads to insufficient model prediction performance. Therefore, datasets with a fully distributed solution space are required that enable effective exploration during model training. In this study, the robustness and predictive capability of the underlying model of a soft sensor was improved by generating synthetic datasets for training. The monitoring of intensified ethanol fermentation is used as a case study. Variational autoencoders were employed to create synthetic datasets, which were then combined with original datasets (experimental) to train neural network regression models. These models were tested on original versus augmented datasets to assess prediction improvements. Using the augmented datasets, the soft sensor predictive capability improved by 34%, and variability was reduced by 82%, based on R2 scores. The proposed method offers significant time and cost savings for dataset generation for the deep learning modeling of ethanol fermentation and can be easily adapted to other fermentation processes. This work contributes to the advancement of soft sensor technology, providing practical solutions for enhancing reliability and robustness in large-scale production. [ABSTRACT FROM AUTHOR]

Growing demand for renewable and sustainable energy sources has prompted research into bioethanol production as a viable alternative to hydrocarbon fuel for automobile engines. Based on their high carbohydrate content, Chlorella vulgaris microalgae were chosen for this study as a feasible biomass for bioethanol synthesis. After conducting microwave-based acid hydrolysis with varying acid concentrations of sulfuric acid (H2SO4) for 1–15 min, this study found that 3% H2SO4 for 5 min yielded the highest yield of reducing sugar (6.77 g/L). In this work, the RSM approach of central composite design (CCD) was utilized for modeling and optimization of ethanol fermentation and the MATLAB Simulink approach was employed for the simulation of ethanol fermentation. This study compared the effects of using Saccharomyces cerevisiae yeast for fermentation at different fermentation times (12 to 48 h), temperatures (28 to 32°C), and size of inoculum (0.5–1.5 g/L). Based on the actual and predicted results, the best conditions for fermentation were 36 h of time, 30°C of temperature, and 1.5 g/L of inoculum size. This gave the maximum ethanol concentration of 3.31 g/L. Furthermore, the RSM method provides minimum error and maximum R² value results for ethanol production compared to MATLAB simulation prediction (MSP). In addition, residue biomass from biofuel production is evaluated for its suitability for a further form of biofuel production. This research explores the opportunities for zero-waste biomass utilization in the development of biofuels. [ABSTRACT FROM AUTHOR]

The unwashed alkali-treated lignocellulose can be directly enzymatically hydrolyzed and fermented via pH adjustment with acids. The use of acids would give a burden on production cost. Furfural residue (FR) which is the acidic solid waste from lignocellulose-derived furfural production process was employed in this study as a pH regulator. The corn cob-derived FR was used to adjust the pH value of alkali-treated corn stover (PCS) to 4.8 for enzymatic hydrolysis and ethanol fermentation. The unwashed PCS adjusted by FR got higher enzymatic hydrolysis efficiency (EHE) than the washed PCS samples. Meanwhile, the mixing of PCS and FR had a synergistic effect on the EHE of PCS. The fermentation of enzymatic hydrolysate from unwashed PCS-FR mixture at 20% solid concentration could attain ethanol production of 26.54 ± 0.02 mg/mL with a yield of 89.53 ± 0.08%. This work created a novel recycling way of FR as a pH regulator for improving the bioconversion of alkali-treated lignocellulose. It also provided a novel clue for the valuable valorization of wastes from corn production. [ABSTRACT FROM AUTHOR]

Bioethanol, a lignocellulosic biofuel, has increased energy sustainability and lessened the environmental effects associated with energy production. Thysanolaena latifolia is a common weed found in the northern part of Thailand that is considered non-food biomass, with a high biomass productivity of approximately 10.2 kg/year. Here, we evaluated the potential of T. latifolia biomass as an environmentally friendly material source for producing alternative bioethanol. To this end, we treated the feedstock under mild conditions using various concentrations of phosphoric acid to create ideal conditions for enzymatic hydrolysis. Pretreatment with 75% phosphoric acid yielded the highest solid recovery (55.8 ± 0.6%) and glucans (93.0 ± 0.3%). Additionally, the hydrolysis efficiency and glucose yield of treated biomass were significantly improved. As a result, the liquid hydrolysate from T. latifolia used for ethanol fermentation by Saccharomyces cerevisiae TISTR 5339 generated 8.9 ± 0.0 g/L ethanol. These findings demonstrate that glucose derived from liquid hydrolysate is a promising sustainable carbon source for producing ethanol from T. latifolia feedstock. Thus, using T. latifolia as a feedstock for generating ethanol can improve the efficiency of bioenergy production. [ABSTRACT FROM AUTHOR]

Bioethanol, an alcohol produced by microbial fermentation, is traditionally produced from sugar-rich plants such as sugar cane, sugar beet and maize. However, there is growing interest in the use of lignocellulose, an abundant and inexpensive renewable energy source, as a potential substitute for the production of biofuels and biochemicals. Yeast Saccharomyces cerevisiae, which is commonly used for ethanol fermentation, cannot cope with lignocellulose due to a lack of lignocellulolytic enzymes and the inefficient functioning of the pentose phosphate pathway. The aim of this research was to isolate yeasts that can efficiently produce bioethanol and valuable byproducts from both glucose and xylose in a two-stage fermentation process using brewer's spent grains. This approach should maximize sugar utilization and improve the economic viability of bioethanol production while contributing to waste valorization and sustainability. Kluyveromyces marxianus and Candida krusei were identified and tested with different initial concentrations of glucose and xylose. The results showed that both yeasts produced bioethanol from glucose but were inefficient with xylose, yielding valuable compounds, such as 2,3-butanediol and glycerol instead. A two-stage fermentation was then carried out with weak acidic hydrolysate from brewer's spent grain. In the first stage, glucose was fermented by S. cerevisiae to produce bioethanol; in the second stage, xylose was fermented by K. marxianus and C. krusei to obtain other valuable products. [ABSTRACT FROM AUTHOR]

A high‐quality filler within mixed matrix membranes, coupled with uniform dispersity, endows a high‐efficiency transfer pathway for the significant improvement on separation performance. In this work, a zeolite‐typed MCM‐22 filler is reported that is doped into polydimethylsiloxane (PDMS) matrix by ultrafast photo‐curing technique. The unique structure of nanosheets assembly layer by layer endows the continuous transfer channels towards penetrate molecules because of the inter‐connective nanosheets within PDMS matrix. Furthermore, an ultrafast freezing effect produced by fast photo‐curing is used to overcome the key issue, namely filler aggregation, and further eliminates defects. When pervaporative separating a 5 wt% ethanol aqueous solution, the resulting MCM‐22/PDMS membrane exhibits an excellent membrane flux of 1486 g m−2 h−1 with an ethanol separation factor of 10.2. Considering a biobased route for ethanol production, the gas stripping and vapor permeation through this membrane also shows a great enrichment performance, and the concentrated ethanol is up to 65.6 wt%. Overall, this MCM‐22/PDMS membrane shows a high separation ability for ethanol benefited from a unique structure deign of fillers and ultrafast curing speed of PDMS, and has a great potential for bioethanol separation from cellulosic ethanol fermentation. [ABSTRACT FROM AUTHOR]

[Display omitted] • A combined fractionation with surfactants and diluted EDA was developed. • PEG8000 addition significantly enhanced lignin removal (68.9%) in the solid fraction. • PEG8000 promoted the preservation of β-O-4 bonds and aliphatic hydroxyl groups in the fractionated lignin. • 137.2 g of ABE solvents could be obtained from 1 kg dried corn stover. In this study, a surfactant-assisted diluted ethylenediamine (EDA) fractionation process was investigated for co-generation of technical lignin and biobutanol from corn stover. The results showed that the addition of PEG 8000 significantly enhanced cellulose recovery (88.9 %) and lignin removal (68.9 %) in the solid fraction. Moreover, the pulp achieved 86.5 % glucose yield and 82.6 % xylose yield in enzymatic hydrolysis. Structural characterization confirmed that the fractionation process promoted the preservation of active β-O-4 bonds (35.8/100R) in isolated lignin and functionalized the lignin through structural modification using EDA and surfactant grafting. The enzymatic hydrolysate of the pulps yielded a sugar solution for acetone-butanol-ethanol (ABE) fermentation, resulting in an ABE concentration of 15.4 g/L and an overall yield of 137.2 g/Kg of dried corn stalk. Thus, the surfactant-assisted diluted EDA fractionation has the potential to enhance the overall economic feasibility of second-generation biofuels production within the framework of biorefinery. [ABSTRACT FROM AUTHOR]

Clostridium acetobutylicum is a solventogenic, anaerobic, gram-positive bacterium that is commonly considered the model organism for studying acetone-butanol-ethanol fermentation. The need to produce these chemicals sustainably and with a minimal impact on the environment has revived the interest in research on this bacterium. The recent development of efficient genetic tools allows to better understand the physiology of this micro-organism, aiming at improving its fermentation capacities. Knowledge about gene essentiality would guide the future genetic editing strategies and support the understanding of crucial cellular functions in this bacterium. In this work, we applied a transposon insertion site sequencing method to generate large mutant libraries containing millions of independent mutants that allowed us to identify a core group of 418 essential genes needed for in vitro development. Future research on this significant biocatalyst will be guided by the data provided in this work, which will serve as a valuable resource for the community. [ABSTRACT FROM AUTHOR]

Background: Saccharomyces cerevisiae is an important microorganism in ethanol synthesis, and with sugarcane molasses as the feedstock, ethanol is being synthesized sustainably to meet growing demands. However, high-concentration ethanol fermentation based on high-concentration sugarcane molasses—which is needed for reduced energy consumption of ethanol distillation at industrial scale—is yet to be achieved. Results: In the present study, to identify the main limiting factors of this process, adaptive laboratory evolution and high-throughput screening (Py-Fe3+) based on ARTP (atmospheric and room-temperature plasma) mutagenesis were applied. We identified high osmotic pressure, high temperature, high alcohol levels, and high concentrations of K+, Ca2+, K+ and Ca2+ (K+&Ca2+), and sugarcane molasses as the main limiting factors. The robust S. cerevisiae strains of NGT-F1, NGW-F1, NGC-F1, NGK+, NGCa2+ NGK+&Ca2+-F1, and NGTM-F1 exhibited high tolerance to the respective limiting factor and exhibited increased yield. Subsequently, ethanol synthesis, cell morphology, comparative genomics, and gene ontology (GO) enrichment analysis were performed in a molasses broth containing 250 g/L total fermentable sugars (TFS). Additionally, S. cerevisiae NGTM-F1 was used with 250 g/L (TFS) sugarcane molasses to synthesize ethanol in a 5-L fermenter, giving a yield of 111.65 g/L, the conversion of sugar to alcohol reached 95.53%. It is the highest level of physical mutagenesis yield at present. Conclusion: Our results showed that K+ and Ca2+ ions primarily limited the efficient production of ethanol. Then, subsequent comparative transcriptomic GO and pathway analyses showed that the co-presence of K+ and Ca2+ exerted the most prominent limitation on efficient ethanol production. The results of this study might prove useful by promoting the development and utilization of green fuel bio-manufactured from molasses. [ABSTRACT FROM AUTHOR]

Agricultural residues are more suitable for biochemical conversion to produce bulk commodities preferentially through anaerobic fermentation with less energy consumption and lower contamination risk. Steam explosion is applicable for industrial production, and biological pretreatment is not suitable for fermentation under pure culture conditions due to its slow rate and contamination risk. Cellulases produced in situ and formulated with glucosidases are cost-effective for building up sugar platforms through simultaneous saccharification and co-fermentation (SSCF) and separate hydrolysis and co-fermentation (SHCF) to produce volatile and nonvolatile products, respectively. In situ utilization of CO 2 can credit cellulosic ethanol, and both yield and titer must be improved substantially for butanol to be produced as an advanced biofuel, but microbial lipids produced aerobically with intensive energy consumption and low yield cannot be affordable as feedstock for biodiesel production. Lignocellulose is an alternative to fossil resources, but its biochemical conversion is not economically competitive. While decentralized processing can reduce logistical cost for this feedstock, sugar platforms need to be developed with energy-saving pretreatment technologies and cost-effective cellulases, and products must be selected correctly. Anaerobic fermentation with less energy consumption and lower contamination risk is preferred, particularly for producing biofuels. Great effort has been devoted to producing cellulosic ethanol, but CO 2 released with large quantities during ethanol fermentation must be utilized in situ for credit. Unless titer and yield are improved substantially, butanol cannot be produced as an advanced biofuel. Microbial lipids produced through aerobic fermentation with low yield and intensive energy consumption are not affordable as feedstocks for biodiesel production. [ABSTRACT FROM AUTHOR]

Summary: This study focuses primarily on the real‐time monitoring of reducing sugar levels throughout solid‐state ethanol fermentation. A predictive model for accurate quantification of reducing sugar levels will be formulated through a comprehensive analysis of near‐infrared spectra across different fermentation stages. Building a predictive model using Adaptive Boosting (AdaBoost), The spectral data was pre‐processed using the Standard Normal Variate (SNV) method, followed by feature band selection using the Genetic Algorithm (GA), resulting in the identification of 181 characteristic wavelengths. The resulting GA‐AdaBoost model has excellent performance metrics: Rc2 of 0.989, RMSEC of 0.393, Rp2 of 0.978, RMSEP of 0.640, RPD of 6.651 and RER of 0.142. Comparative evaluations against Competitive Adaptive Reweighted Sampling (CARS), Successive Projection Algorithm (SPA), Uninformative Variable Elimination (UVE) and Principal Component Analysis (PCA) consistently underscore the superior efficacy of the GA‐AdaBoost model. These results robustly confirm its reliability in accurately quantifying reducing sugars in solid‐state fermentation processes. [ABSTRACT FROM AUTHOR]

Saccharomyces cerevisiae is a widely used strain for ethanol fermentation; meanwhile, efficient utilization of glucose could effectively promote ethanol production. The PFK1 gene is a key gene for intracellular glucose metabolism in S. cerevisiae. Our previous work suggested that although deletion of the PFK1 gene could confer higher oxidative tolerance to S. cerevisiae cells, the PFK1Δ strain was prone to contamination by other microorganisms. High interspecies microbial competition ability is vital for the growth and survival of microorganisms in co-cultures. The result of our previous studies hinted us a reasonable logic that the EMP (i.e., the Embden-Meyerhof-Parnas pathway, the glycolytic pathway) key gene PFK1 could be involved in regulating interspecies competitiveness of S. cerevisiae through the regulation of glucose utilization and ethanol production efficiency. The results suggest that under 2% and 5% glucose, the PFK1Δ strain showed slower growth than the S288c wild-type and TDH1Δ strains in the lag and exponential growth stages, but realized higher growth in the stationary stage. However, relative high supplement of glucose (10%) eliminated this phenomenon, suggesting the importance of glucose in the regulation of PFK1 in yeast cell growth. Furthermore, during the lag growth phase, the PFK1Δ strain displayed a decelerated glucose consumption rate (P < 0.05). The expression levels of the HXT2, HXT5, and HXT6 genes decreased by approximately 0.5-fold (P < 0.05) and the expression level of the ZWF1 exhibited a onefold increase in the PFK1Δ strain compared to that in the S. cerevisiae S288c wild-type strain (P < 0.05).These findings suggested that the PFK1 inhibited the uptake and utilization of intracellular glucose by yeast cells, resulting in a higher amount of residual glucose in the medium for the PFK1Δ strain to utilize for growth during the reverse overshoot stage in the stationary phase. The results presented here also indicated the potential of ethanol as a defensive weapon against S. cerevisiae. The lower ethanol yield in the early stage of the PFK1Δ strain (P < 0.001) and the decreased expression levels of the PDC5 and PDC6 (P < 0.05), which led to slower growth, resulted in the strain being less competitive than the wild-type strain when co-cultured with Escherichia coli. The lower interspecies competitiveness of the PFK1Δ strain further promoted the growth of co-cultured E. coli, which in turn activated the ethanol production efficiency of the PFK1Δ strain to antagonize it from E. coli at the stationary stage. The results presented clarified the regulation of the PFK1 gene on the growth and interspecies microbial competition behavior of S. cerevisiae and would help us to understand the microbial interactions between S. cerevisiae and other microorganisms. Key points: • PFK1Δ strain could realize reverse growth overshoot at the stationary stage • PFK1 deletion decreased ethanol yield and interspecific competitiveness • Proportion of E. coli in co-culture affected ethanol yield capacity of yeast cells [ABSTRACT FROM AUTHOR]

Background: The abundance of glucuronoxylan (GX) in agricultural and forestry residual side streams positions it as a promising feedstock for microbial conversion into valuable compounds. By engineering strains of the widely employed cell factory Saccharomyces cerevisiae with the ability to directly hydrolyze and ferment GX polymers, we can avoid the need for harsh chemical pretreatments and costly enzymatic hydrolysis steps prior to fermentation. However, for an economically viable bioproduction process, the engineered strains must efficiently express and secrete enzymes that act in synergy to hydrolyze the targeted polymers. Results: The aim of this study was to equip the xylose-fermenting S. cerevisiae strain CEN.PK XXX with xylanolytic enzymes targeting beechwood GX. Using a targeted enzyme approach, we matched hydrolytic enzyme activities to the chemical features of the GX substrate and determined that besides endo-1,4-β-xylanase and β-xylosidase activities, α-methyl-glucuronidase activity was of great importance for GX hydrolysis and yeast growth. We also created a library of strains expressing different combinations of enzymes, and screened for yeast strains that could express and secrete the enzymes and metabolize the GX hydrolysis products efficiently. While strains engineered with BmXyn11A xylanase and XylA β-xylosidase could grow relatively well in beechwood GX, strains further engineered with Agu115 α-methyl-glucuronidase did not display an additional growth benefit, likely due to inefficient expression and secretion of this enzyme. Co-cultures of strains expressing complementary enzymes as well as external enzyme supplementation boosted yeast growth and ethanol fermentation of GX, and ethanol titers reached a maximum of 1.33 g L− 1 after 48 h under oxygen limited condition in bioreactor fermentations. Conclusion: This work underscored the importance of identifying an optimal enzyme combination for successful engineering of S. cerevisiae strains that can hydrolyze and assimilate GX. The enzymes must exhibit high and balanced activities, be compatible with the yeast's expression and secretion system, and the nature of the hydrolysis products must be such that they can be taken up and metabolized by the yeast. The engineered strains, particularly when co-cultivated, display robust growth and fermentation of GX, and represent a significant step forward towards a sustainable and cost-effective bioprocessing of GX-rich biomass. They also provide valuable insights for future strain and process development targets. [ABSTRACT FROM AUTHOR]

Bioethanol is an organic compound resulted from the fermentation of sugar substrates by microorganisms which is used as alternative energy sources. During bioethanol fermentation yeast are exposed to various fermentation stresses, including temperature, osmotic, and oxidative stresess. Such conditions may decrease ethanol production. We previously isolated fermentation-stress tolerance yeast isolates from traditional Balinese beverages, identified as Wickerhamomyces anomalus BT2, BT5, and BT6. However no data available regarding the bioethanol production of those isolates. Our study indicates that these strains could utilize various sugar substrates (glucose, xylose, maltose, sucrose) in oxidative fermentative media. The highest value of substrate utilization efficiency following 48 hours fermentation was shown by BT6 on glucose (61.02%), BT 2 on xylose (55.44%) and maltose (60.90%). Measurement of ethanol production by Gas Chromatography showed that the strains were able to produce higher ethanol on the glucose substrate than other substrates. For instance, BT6 could produce the highest ethanol production (5.00 g/L) amongst strains tested by using glucose as substrate. Yet, the particular strains could only produce 0.30 g/L and 0.65 g/L by using xylose and maltose, respectively. For further genetic engineering purposes, we detected ADH1 gene from all three isolates, with high homology to the alcohol dehydrogenase from Saccharomyces cerevisiae, Geobacillus stearothermophilus and Pseudomonas aeruginosa. Further strain development can be carried out targeting the ADH1 gene, important for ethanol fermentation. [ABSTRACT FROM AUTHOR]

The co-cultivation of sake yeast (AK25, K901, K1401, or K1801 strain) and the kuratsuki Bacillus A-10 and/or Priestia B-12 strains in koji solution was performed to demonstrate the effects of these two kuratsuki bacteria on sake taste. The results showed that the Brix and acidity patterns of sake preparations produced with and without these kuratsuki bacteria were very similar. This indicated that the addition of these kuratsuki bacteria did not inhibit ethanol fermentation or organic acid production by sake yeast. A taste recognition device showed that the effects of these kuratsuki bacteria on the saltiness and sourness of sake were greater than those on other taste properties. Astringency stimulation and saltiness of sake produced using the sake yeast K901 were increased by Bacillus A-10 and decreased by Priestia B-12. Except for these two cases, the taste intensities of sake preparations produced with the Bacillus A-10 and Priestia B-12 strains were very similar, but differed from those of sake produced with kuratsuki Kocuria. These results support our hypothesis that the flavor and taste of sake can be controlled by utilizing the interactions between kuratsuki bacteria and sake yeast. For crating the desired sake taste, a combination of kuratsuki bacteria and sake yeast should be considered. [ABSTRACT FROM AUTHOR]

To improve ethanol production, carbon and microbial sources were derived from corncob and molasses. Before investigating simultaneous saccharification and fermentation (SSF), the boiled corncob was vacuum-ensiled and the molasses was diluted. The optimal ensiling time of 4 days increased not only the amount of fermentable sugar but also the population of beneficial microorganisms. The proper dilution of molasses at a ratio of 1:3 molasses to boiled water reduced both the contamination problem and the inhibition of ethanol fermentation. The combination of the ensiled corncob and the diluted molasses could provide a substrate that is suitable for SSF without the addition of enzymes, supplements, or yeast strains. The substrate contained the optimal concentration of initial sugar (174.631 ± 0.975 g/L) and viable microorganisms (1.9×106 ± 0.1×106 CFU/mL of total bacteria and 1.0x105 ± 0.1×105CFU/mL of yeast) that could continue to hydrolyze and ferment carbohydrates in the substrate for the SSF. Using a ratio of 1:3 of ensiled corncob to diluted molasses, a pH of 4.5, and a temperature of 27 °C for 72 h, the SSF produced the highest concentration of ethanol at 93.345 ± 0.062 g/L. This work provides a cost-effective process that requires no enzyme or yeast, is simply technology, and is friendly to the environment, while the remaining solid fraction can be utilized as a suitable feedstock for biogas production. [ABSTRACT FROM AUTHOR]

Saccharomyces cerevisiae is a widely used strain for ethanol fermentation; meanwhile, efficient utilization of glucose could effectively promote ethanol production. The PFK1 gene is a key gene for intracellular glucose metabolism in S. cerevisiae. Our previous work suggested that although deletion of the PFK1 gene could confer higher oxidative tolerance to S. cerevisiae cells, the PFK1Δ strain was prone to contamination by other microorganisms. High interspecies microbial competition ability is vital for the growth and survival of microorganisms in co-cultures. The result of our previous studies hinted us a reasonable logic that the EMP (i.e., the Embden-Meyerhof-Parnas pathway, the glycolytic pathway) key gene PFK1 could be involved in regulating interspecies competitiveness of S. cerevisiae through the regulation of glucose utilization and ethanol production efficiency. The results suggest that under 2% and 5% glucose, the PFK1Δ strain showed slower growth than the S288c wild-type and TDH1Δ strains in the lag and exponential growth stages, but realized higher growth in the stationary stage. However, relative high supplement of glucose (10%) eliminated this phenomenon, suggesting the importance of glucose in the regulation of PFK1 in yeast cell growth. Furthermore, during the lag growth phase, the PFK1Δ strain displayed a decelerated glucose consumption rate (P < 0.05). The expression levels of the HXT2, HXT5, and HXT6 genes decreased by approximately 0.5-fold (P < 0.05) and the expression level of the ZWF1 exhibited a onefold increase in the PFK1Δ strain compared to that in the S. cerevisiae S288c wild-type strain (P < 0.05).These findings suggested that the PFK1 inhibited the uptake and utilization of intracellular glucose by yeast cells, resulting in a higher amount of residual glucose in the medium for the PFK1Δ strain to utilize for growth during the reverse overshoot stage in the stationary phase. The results presented here also indicated the potential of ethanol as a defensive weapon against S. cerevisiae. The lower ethanol yield in the early stage of the PFK1Δ strain (P < 0.001) and the decreased expression levels of the PDC5 and PDC6 (P < 0.05), which led to slower growth, resulted in the strain being less competitive than the wild-type strain when co-cultured with Escherichia coli. The lower interspecies competitiveness of the PFK1Δ strain further promoted the growth of co-cultured E. coli, which in turn activated the ethanol production efficiency of the PFK1Δ strain to antagonize it from E. coli at the stationary stage. The results presented clarified the regulation of the PFK1 gene on the growth and interspecies microbial competition behavior of S. cerevisiae and would help us to understand the microbial interactions between S. cerevisiae and other microorganisms. Key points: • PFK1Δ strain could realize reverse growth overshoot at the stationary stage • PFK1 deletion decreased ethanol yield and interspecific competitiveness • Proportion of E. coli in co-culture affected ethanol yield capacity of yeast cells [ABSTRACT FROM AUTHOR]

[Display omitted] • Structures of DESs affected the pretreatment efficiency and ethanol fermentation. • Lactic acid/guanidine hydrochloride effectively removed lignin and xylan. • The hydrolysates of various DES pulps had impressive ethanol yields. • 302.75 g ethanol and 118.98 g lignin were harvested from 1 kg dried biomass. Deep eutectic solvents (DESs) offer a potential opportunity in biomass utilization industries. This work emphasized the impact of hydrogen bond donors (HBD) and acceptors (HBA) on deconstruction and valorization of rice straw. Acidity, alkyl chain length, hydrogen bonding ability and functional groups of HBD and HBA appeared to be important factors affecting the fractionated pulps and lignins, which further influenced ethanol fermentation. Among the candidate DESs, lactic acid/guanidine hydrochloride (LGH) was proved to be the most suitable one due to the excellent delignification and xylan removal. For the downstream fermentation process, 0.47 g g−1 of bioethanol with 0.55 g/L h−1 of productivity can be obtained from the LGH pulp's hydrolysate. Mass balance showed 302.8 g bioethanol and 119.0 g technical lignin can be co-generated from 1 kg dried rice straw. This "green" valorization strategy offers a promising scheme in biorefinery of lignocelluloses. [ABSTRACT FROM AUTHOR]

In this study, sorghum meal underwent 2–10 kGy electron beam irradiation (EBI) to investigate alterations in its elemental composition, relevant physicochemical characteristics, and enzymatic hydrolysis fermentation properties. The results indicated a decrease in amylose content and an increase in reducing sugar content in sorghum meal after EBI, along with severe damage to the internal structure of starch granules, leading to increased solubility in water. Furthermore, irradiation enhanced the shear resistance and gelatinization stability of sorghum meal paste. Most importantly, EBI-induced degradation of sorghum starch molecules enhanced their susceptibility to interact with α-amylase, significantly improving the enzymatic hydrolysis and alcohol fermentation efficiency of sorghum meal. At an irradiation dose of 8 kGy, raw and cooked sorghum meal exhibited a 43.40% and 33.33% increase in ethanol concentration and a 43.44% and 30.29% increase in ethanol yield, respectively. This finding indicated that irradiation is an effective pretreatment method for starch-based ethanol fermentation. [Display omitted] • Using EBI as a pretreatment for sorghum meal ethanol fermentation. • Sorghum starch molecules degraded after EBI treatment. • EBI notably enhanced sorghum meal's enzymatic saccharification efficiency. • The ethanol concentration and yield peaked at an EBI dose of 8 kGy. • EBI coupled with high-temperature cooking notably improved fermentation efficiency. [ABSTRACT FROM AUTHOR]

Laccase mediators possess advantage of oxidizing substrates with high redox potentials, such as aflatoxin B 1 (AFB 1). High costs of chemically synthesized mediators limit laccase industrial application. In this study, thin stillage extract (TSE), a byproduct of corn-based ethanol fermentation was investigated as the potential natural mediator of laccases. Ferulic acid, p -coumaric acid, and vanillic acid were identified as the predominant phenolic compounds of TSE. With the assistance of 0.05 mM TSE, AFB 1 degradation activity of novel laccase Glac1 increased by 17 times. The promoting efficiency of TSE was similar to ferulic acid, but superior to vanillic acid and p- coumaric acid, with 1.2- and 1.3-fold increases, respectively. After Glac1-TSE treatment, two oxidation products were identified. Ames test showed AFB 1 degradation products lost mutagenicity. Meanwhile, TSE also showed 1.3–3.0 times promoting effect on laccase degradation activity in cereal flours. Collectively, a safe and highly efficient natural mediator was obtained for aflatoxin detoxification. [Display omitted] • Thin stillage extract (TSE) is a cost-saving, efficient and natural laccase mediator. • Dominant phenolic acids of TSE are ferulic acid, p -coumaric acid and vanillic acid. • A novel Glac1 is a high sensitive laccase to mediator TSE on AFB 1 degradation. • Glac1-TSE possessed high activity on AFB 1 detoxification in cereal flours. [ABSTRACT FROM AUTHOR]

• Both membership function classification method and principal component analysis comprehensive evaluation method can be used to evaluate the waterlogging tolerance of pumpkin resources. • Of the 27 pumpkin germplasm, 20 were evaluated as MWT, 4 as WT, and 1 each as HWT, WS, and HWS. • The water-resistant pumpkin can maintain the balance of reactive oxygen synthesis and removal, the membrane peroxidation degree is low, and more chlorophyll can be synthesized to resist stress. This study used 27 Chinese pumpkin resources for the waterlogging treatment and analyzed 16 growth and physiological indicators, including plant height and stem diameter. The waterlogging-tolerant and waterlogging-sensitive pumpkin resources were selected using the membership function grading method and principal component analysis. The changes in the biochemical indicators of pumpkins under waterlogging stress were also studied. The results showed that among the 27 pumpkin resources, five were waterlogging-tolerant materials ('013-2′, 'Changyi', 'Universal female parent', '450′, and 'Changer'), two were waterlogging-sensitive materials ('063-2′ and '367-2′), and the remaining were moderately tolerant to waterlogging. Waterlogging stress increased the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) and the contents of proline and pyruvate in pumpkins, which were higher in waterlogging-tolerant pumpkins than in waterlogging-sensitive ones. The malondialdehyde content of the waterlogging-tolerant pumpkins was lower than that of the waterlogging-sensitive ones. The alcohol dehydrogenase (ADH) and pyruvate dehydrogenase complex (PDC) activities in the root of waterlogging-tolerant pumpkins showed an upward trend, while the lactate dehydrogenase (LDH) activity showed an initial downward trend and then upward trend. The ADH, PDC, and LDH enzyme activities of the waterlogging-sensitive pumpkins increased initially and then decreased. The contents of chlorophyll a, chlorophyll b , total chlorophyll, and carotenoids in the waterlogging-sensitive pumpkins decreased, while those of the waterlogging-tolerant pumpkins increased. Additionally, waterlogging-tolerant pumpkins could maintain a good balance between the synthesis and clearance of reactive oxygen species, with a low degree of membrane lipid peroxidation, and synthesize more chlorophyll to resist waterlogging stress. The waterlogging-tolerant pumpkins mainly underwent ethanol fermentation in the early stages of waterlogging stress, followed by combined ethanol and lactic acid fermentation. However, the waterlogging-sensitive pumpkins mainly underwent lactic acid fermentation in the early stages of waterlogging stress. These findings provide a basis for the research on the waterlogging tolerance mechanism of pumpkins and the selection of the rootstock varieties of edible waterlogging-tolerant pumpkins. [ABSTRACT FROM AUTHOR]

The iron ion-catalyzed hydrogen peroxide pretreatment (Fe-HP pretreatment) can be used as a green pretreatment way for promoting bio-refining of corncob and bio-jet fuel production. [Display omitted] • An environmentally friendly Fe-HP biomass pretreatment was developed. • Fe-HP pretreatment significantly improved bio-jet fuel production. • The existence and role of ROS in the Fe-HP pretreatment process was confirmed. • Dual functional catalyst improved the selectivity of bio-jet fuels. • High ethanol conversion (95.9 %) with a 70.9 % jet-fuel selectivity was obtained. Developing efficient and green pretreatment pathways is of great significance for the production of biofuels. The purpose of this work is to evaluate that iron-ion catalyzed hydrogen peroxide (Fe-HP) pretreatment can be used for the enhancement of bio-jet fuel production using corncob as a typical lignocellulosic biomass. Typically, the Fe-HP pretreatment was conducted under the following pretreatment conditions: H 2 O 2 concentration of 5.0 wt%, iron ion concentration of 400 ppm, biomass loading of 10 wt%, 70 °C and 60 min. The Fe-HP pretreated corncob shows a high sugar yield of 39.2 % (w/w) under the optimal enzymolysis conditions (50 ℃, pH 4.8, 72 h). Ethanol yield of 35.2 % (w/w) was obtained under the optimal fermentation conditions (30 ℃, pH 5.5, 72 h). Especially, the directional transformation of corncob to bio-jet fuels was achieved by integrating biomass fermentation and catalytic synthesis. High ethanol conversion of 95.9C-mol % and good jet fuel selectivity of 70.9C-mol % were obtained by using the bi-functional catalyst (HSAPO-34/NiHβ) under the optimal synthesis conditions (200 °C, 5 MPa, 3 h). Based on the biomass characterization and reactive oxygen specie's analysis, the possible role and mechanism of the iron-ion catalyzed hydrogen peroxide pretreatment was addressed. The iron ion catalyst can accelerate the decomposition of hydrogen peroxide to form hydroxyl radicals, and thus promoting biomass depolymerization and lignin removal from lignocellulose. The pretreatment increased sugar yield and concentration during enzymatic hydrolysis, which indirectly enhanced ethanol fermentation and bio-jet fuel production. [ABSTRACT FROM AUTHOR]

Effective pretreatment is essential for successfully utilizing renewable resources such as lignocellulosic biomass in the production of bioethanol. In this study, ternary deep eutectic solvents (DESs), namely choline chloride/lactic acid/glycerol (ChCl/LA/Gly), choline chloride/oxalic acid/glycerol (ChCl/OA/Gly), choline chloride/lactic acid/ethylene glycol (ChCl/LA/EG), and choline chloride/oxalic acid/ethylene glycol (ChCl/OA/EG) were prepared and employed for the pretreatment of cellulose-rich Napier grass (NG). Post treatment, the NG hydrolysate was subjected to enzymatic saccharification followed by ethanol fermentation. The results showed effective delignification of NG after treatment with the prepared ternary DESs, with ChCl/LA/EG removing a maximum of 92.89% lignin. The efficiency of the prepared DESs is attributed to their low densities, pH, and viscosity. Enzymatic saccharification of ChCl/LA/EG-treated NG resulted in a 1.68 fold increase in reducing sugar yield compared to that of untreated NG. All pretreated NG produced more bioethanol via a separate hydrolysis and fermentation (SHF) process than untreated NG after Saccharomyces cerevisiae fermentation. A maximum of 0.37 g bioethanol/g of biomass was obtained from the one-pot process using ChCl/LA/Gly pretreatment. FTIR and XRD analyses of untreated and pretreated NG corroborated the efficacy of the ternary DESs on cellulose recovery and delignification. Also, enzymatic and microbial inhibition studies on the prepared DESs show their potential to be employed in a one-pot process for biorefinery. The results of the present investigation show the potential of utilizing eco-friendly DESs and renewable resources for the production of bioethanol, a viable option to fossil fuels. [ABSTRACT FROM AUTHOR]

Addressing the high cost of comprehensive utilization of lignocellulose, an efficient and green lignocellulosic biorefinery process was developed in this study, which can achieve the co-production of lignin, sugar and lipid. A series of FDES were prepared using glycerin, choline chloride (ChCl), and H 2 SO 4 for the pretreatment of lignocellulose and ultimately for fermentation. After optimization, the hemicellulose removal reaches 98 %, and enzymatic hydrolysis rate of pretreated solids exceeds 90 %. The FDES was then recovered and reused for pretreatment, in total five batches of lignocellulose were pretreated, only a slight decrease in lignin and hemicellulose removal rate occurred, no significant decrease in lignin yield, and a decrease in solid enzyme hydrolysis from 83.26 % to 78.25 %. Finally, FDES after using five batches was used as a substrate for Rhodotorula glutinis with biomass up to 40.25 g/L and lipid concentration up to 8.33 g/L. In addition, the cellulose was probed with high solid-loading enzymatic hydrolysis, obtaining high concentration of glucose (137.4 g/L) for ethanol fermentation. In conclusion, this study developed a biorefinery technology for the efficient utilization of lignocellulosic fractions and pretreatment solvents, which reduces the cost of DES pretreatments of lignocellulose, and achieves the cogeneration of lignin, sugar and lipids. [Display omitted] [ABSTRACT FROM AUTHOR]

The WGS of Klebsiella sp. SWET4 revealed a genome of 5,665,821 bp by assembling 78 scaffolds with N50 and L50 values of 371571 and 5, respectively. BUSCO and ortholog analysis indicated the completeness of the genome and familiarity with Klebsiella variicola. Annotation result confirmed the presence of 5 major cellulose metabolizing genes (bcsZ, bglC, bglA, celA, chbA), besides 4 key xylan degrading genes (xynB, xynT, xylA, xylB) and 4 principal ethanol fermentation (nifJ, adhE, acs, adh1) genes. The lignolytic potential of SWET4 was evident in the kinetic study and the presence of yfeX / efeB , katG , katE , etc. genes were confirmed. Expression study with qPCR indicated overexpression of cellulolytic genes (268.73-fold of bglA , 122.78-fold of bglC , and 45.88-fold of bcsZ) in cellulose broth when compared to glucose. However, less activity was observed for xylanolytic genes (9.19-fold of xylA , 4.29-fold of xylB , and 2.89-fold of xynB) in xylan broth. Additionally, the kinetic study revealed that K s was significantly lower for cellulose (7.79 and 0.09 g/L) compared to xylan (193.78 and 3.95 g/L) for primary and secondary growth phases, respectively which confirmed the higher preference of cellulose by SWET4. Further, ethanol estimation by HPLC exhibited an increase in ethanol concentration in banana peel fermentation broth from 0.1 g/L (30 h) to 0.35 g/L (56 h). The adh1 gene expression was also found to increase by 84.45-fold, whereas adhE increased by 1.62-fold confirming their influence on ethanol production. This study confirmed the lignocellulolytic and ethanologenic properties of SWET4 enabling the direct biotransformation of cellulosic biomass to ethanol. [Display omitted] • The WGS of Klebsiella sp. SWET4 was reviled the genome size of 5665821 bp. • Completeness of the constructed genome was studied by BUSCO and ortholog analysis. • bglA exhibited 268.73-fold and xylA 9.19-fold of overexpression by qPCR study. • adh1 exhibited 84.4-fold increase resulting 35-fold increase in ethanol production. • Metabolic pathway from plant polysaccharide to ethanol was established. [ABSTRACT FROM AUTHOR]

Pretreatment of lignocellulosic biomass by breaking down its complex structure is an essential step to facilitate enzymatic hydrolysis of lignocellulose and subsequent bioethanol fermentation. Herein, an eco-friendly pretreatment strategy was developed by applying deep eutectic solvent (DES) cocktail. Attributing to the synergistic effect of two DESs (e.g., betaine-glycerol and choline chloride-oxalic acid (or choline chloride-acetamide)), an impressive 89.51% digestibility for glucan and 75.43% for xylan were achieved. Characterization of pretreated corn stover showed that DES cocktail changed substrate surface structure and enlarged structure pores, which could improve the accessibility of cellulase. The pretreated corn stover was also employed in ethanol fermentation and achieved the yield of 73.35%. Recycling experiments demonstrated the potential reusability of DES cocktail in a sustainable manner towards various biomass sources. These findings highlight the effectiveness and versatility of the developed DES cocktail pretreatment method, paving the way for sustainable bioethanol production from lignocellulosic feedstocks. [Display omitted] • Betaine-glycerol based DES cocktail was developed for corn stover pretreatment. • DES cocktail pretreatment increased glucan recovery up to 13.1% compared to single DES pretreatment. • The saccharification rate of enzyme-digested glucose after optimization of pretreatment temperature was as high as 89.51%. • Ethanol yield reached 73.61% with a maximum increase of 10.16% after DES cocktail pretreatment. • DES cocktails maintained ∼83% pretreatment effect after four recovery cycles. [ABSTRACT FROM AUTHOR]

Biodegradable mulch film has become an encouraging alternative to conventional petroleum–based plastic, but it is likely to generate more microplastics (MPs) than conventional films with lower resistance and thus profoundly affects the soil environment. However, the effects of biodegradable (BMPs) and conventional polyethylene MPs (PE–MPs) on soil microbial carbon (C) cycle remain unclear. Here, metagenomic sequencing was used to investigate microbial functional and relative taxonomic traits in response to PE–MP and BMP addition (5 % w/w) via a soil microcosm experiment. The results showed that the presence of BMPs, rather than PE–MPs, significantly changed soil microbial C cycling patterns at the functional and taxonomic levels. In soils, BMP addition significantly increased the abundances of genes regulating aerobic respiration, C decomposition (intracellular), C fixation, fermentation and CO oxidation pathways compared to those in the control and PE–MP added soils. Specifically, BMPs promoted soil starch and PHA (liable C) degradation, acetate and ethanol fermentation, Calvin–Benson–Bassham (CBB) cycle and 3–hydroxypropionate/4–hydroxybutyrate (3HP/4HB) associated with C fixation. Most of these C cycling pathways were further strengthened in the microplastisphere of BMPs. Furthermore, MPs selectively enriched specific taxa on their surface and subsequently increased their abundance in soils; Bradyrhizobium , Ramlibacter and Variovorax (enriched by BMPs) positively regulated labile C degradation, and Amycolatopsis and Nocardia (enriched by PE–MPs) promoted recalcitrant C degradation. Moreover, Pseudonocardia and Variovorax that were enriched by BMPs improved C dissimilation and assimilation by regulating fermentation and C fixation processes, respectively. Taken together, these results improve the understanding of the influence of conventional and biodegradable MPs on soil C cycling pathways and related microbial communities, highlighting that the presence of BMPs rather than PE–MPs accelerates soil C turnover. • BMPs rather than PE–MPs significantly affected microbial functions involved in soil C cycle. • BMPs addition promoted multiple processes of microbial carbon metabolisms. • Proteobacteria and its genera enriched by BMPs improved liable C degradation. • PE – MPs enriched Amycolatopsis and Nocardia that regulated recalcitrant C decomposition. • Pseudonocardia and Variovorax significantly regulated fermentation and C fixation metabolisms. [ABSTRACT FROM AUTHOR]

Sugarcane molasses is one of the main raw materials for bioethanol production, and Saccharomyces cerevisiae is the major biofuel-producing organism. In this study, a batch fermentation model has been used to examine ethanol titers of deletion mutants for all yeast nonessential genes in this yeast genome. A total of 42 genes are identified to be involved in ethanol production during fermentation of sugarcane molasses. Deletion mutants of seventeen genes show increased ethanol titers, while deletion mutants for twenty-five genes exhibit reduced ethanol titers. Two MAP kinases Hog1 and Kss1 controlling the high osmolarity and glycerol (HOG) signaling and the filamentous growth, respectively, are negatively involved in the regulation of ethanol production. In addition, twelve genes involved in amino acid metabolism are crucial for ethanol production during fermentation. Our findings provide novel targets and strategies for genetically engineering industrial yeast strains to improve ethanol titer during fermentation of sugarcane molasses. • Screening 4797 gene mutants for ethanol fermentation titers of sugarcane molasses. • Forty-two genes involved in ethanol production in sugarcane molasses fermentation. • Seventeen mutants show increased, but 25 mutants exhibit reduced, ethanol yields. • Two MAP kinases Hog1 and Kss1 negatively regulate ethanol production. • Amino acid metabolism are crucial for ethanol production during fermentation. [ABSTRACT FROM AUTHOR]

Several lignocellulosic wastes are generated in the pulp and paper industry (PPI), such as small wood chips (pinchips) and paper sludge, presenting a high cellulose content suitable to be converted into biofuels or bio-products in a forest biorefinery scheme. In this work, two schemes of biorefinery were proposed for their valorization, processing small eucalyptus wood pinchips in two different strategies: (i) autohydrolysis at 230ºC, and (ii) autohydrolysis at 195ºC followed by organosolv process (47.7% ethanol-water, 198ºC for 60 min). More than 95% of cellulose was recovered in both schemes. In the combined process, 76% of delignification was achieved and 78% of xylan was solubilized as xylooligosaccharides. To reduce operational cost of lignocellulosic biomass-to-ethanol fermentation, the mixture of the treated eucalyptus pinchips from two processes with sludge was also proposed to increase the initial glucan content and to supply a rich source of nitrogen (present in the sludge). For that, two experimental designs were carried out for ethanol production by simultaneous saccharification and fermentation (SSF) process. Ethanol from SSF assays using sludge as co-substrate at 0.6 g of sludge/g of treated wood pinchips and 16 FPU/g of pretreated solids allowed to obtain 59 g/L (90% of conversion) and 46 g/L (96% of conversion) when blended with the wood from autohydrolysis and with the wood from autohydrolysis followed by organosolv, respectively. Overall, this study shows an alternative process valorization of biomasses derived from PPI for production of advanced biofuels and bio-products (such as xylooligosaccharides and lignin) contributing to achieving a circular economy. • Multi-waste valorization approach was proposed to produce biofuel and bioproducts. • Autohydrolysis and organosolv processes allowed > 90% glucan recoveries. • Higher than 40 g/L of ethanol and 90% of yield were obtained in both schemes developed. • Blending with sludge improve ethanol production from pretreated eucalyptus wood. [ABSTRACT FROM AUTHOR]

• Upgrading DAP by post-hydrolysis for carbon efficient conversion of lignocellulose. • A radar chart method was used for the comprehensive evaluation of DAP performance. • One-pot post-hydrolysis and SSF without detoxification and sterilization. • Preserved 45.2 % of original β-O-4 linkages in fractionated lignin. • 66 % of lignocellulose carbon was recovered as ethanol, xylose and reactive lignin. Dry acid pretreatment (DAP) as a promising process for industrial biorefinery provide an efficient bioconversion of cellulose without free wastewater, although the partial xylan and lignin degrade to inhibitors or recondense. A biorefinery strategy for carbon efficient conversion of lignocellulose into bioethanol, xylose, and reactive lignin was developed by upgrading DAP with post-hydrolysis. The results showed that lignocellulose after mild DAP (175 °C, acid dosage of 15 mg/g dry material) obtained higher xylan recovery and lower inhibitors than that of general DAP. Subsequently, post-hydrolysis, simultaneous saccharification and ethanol fermentation were performed at solids loading of 20 wt% without detoxification and sterilization, resulting in xylose and ethanol yield of 71.8 % and 67.6 %. The fractionated lignin presented more reactive β-aryl ether linkages and less condensation than that from DAP. 66 % of lignocellulose carbon was recovered as ethanol, xylose and reactive lignin. This upgrading biorefinery strategy provided an easy-to-operate process for integrated utilization of lignocellulose. [ABSTRACT FROM AUTHOR]

Lipid-extracted algae (LEA) can be processed via acetone, butanol and ethanol fermentation to produce butanol as an additive to algal biofuel, but direct fermentation was ineffective. In this study, nitrogen and phosphorus regulation for algae cultivation was applied to modify the biochemical composition of algal biomass and hence improve butanol production from LEA. The results show that when nitrogen starvation and excess phosphorus were used during algae cultivation, a significant rise of starch productivity and decline of protein productivity for algal biomass were obtained, which resulted in the highest butanol productivity of 20.16 mg L−1 d−1, a 5.48-fold increase over traditional one-stage cultivation. Mechanism analysis suggested that nitrogen starvation enhanced lipid and starch contents and reduced protein content, which modified C/N ratio of LEA, prevented acid crash and improved butanol production; excess phosphorus modified amino acid contents of phenylalanine and arginine, which strengthened fluxes directing to butanol generation. Through this investigation, the approach of using nitrogen starvation and excess phosphorus to modify biochemical composition of algal biomass and subsequently improve butanol production of LEA was demonstrated to be applicable. [Display omitted] [ABSTRACT FROM AUTHOR]

Hydrocotyle verticillata can tolerate varying degrees of flooding, up to complete submergence, and is at the same time extremely sensitive to drought. Understanding the structural and biochemical principles of these unusual tolerance limits is of particular importance. We analyzed the effect of soil flooding, complete submergence (rooted plants and floating stems), and dehydration on root anatomy, alcohol dehydrogenase (ADH), heat shock proteins 70 (HSP70), hydrogen peroxide, and DNA integrity using light microscopy, biochemical and histological methods. It was shown that anatomical traits of adventitious roots with a triarch stele were similar in the plants growing under different conditions; the single-layered and thin-walled epidermis formed relatively short root hairs; essential air spaces were absent in the cortex parenchyma. Results on ADH clearly showed that anaerobic energetic metabolism in root apices and individual rhizoderma cells of the mature root zone was normal for this species in optimal and suboptimal conditions, while leaves changed metabolism to anaerobic in response to submergence. Alterations in the protein spectrum were accompanied by adequate up-regulation of HSP70 under different levels of flooding and dehydration/rehydration. These results appear to indicate a flooding adaptation strategy for H. verticillata based primarily on metabolic plasticity rather than morphoanatomical adaptations. Most notably, the resistance of this species to long-term submergence has been associated with strong ADH induction in leaves, transient activation of 70 kDa isoform of HSP70 and induction of 66 kDa isoform, as well as a significant delay in the accumulation of hydrogen peroxide and DNA degradation. • Hydrocotyle verticillata tolerates varying degrees of flooding up to submergence. • Essential air spaces were absent in the root cortex parenchyma. • Ethanol fermentation was normal for roots and was induced in submerged leaves. • Up-regulation of HSP70 responded to both flooding and dehydration. • Delayed ROS production and DNA degradation were associated with leaf flood resistance. [ABSTRACT FROM AUTHOR]