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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]

The medium composition and fermentation parameters play a critical role in the fermentation process. Therefore, in the present study, the effects of fermentation parameters (initial glucose concentration (IGC), inoculation ratio (IR), initial pH value (IPV), stirring rate (SR), and temperature (T)) and medium composition (yeast extract (YE) and peptone (PEP)) on bioethanol production from glucose by using Scheffersomyces stipitis in shake flask fermentation were studied, respectively. According to results, the highest ethanol yield (YP/S) was achieved to be 47.63% when IGC, IR, IPV, SR, T, and nitrogen concentrations were 15 g/L, 5% (v/v), 5.5, 150 rpm, 30 °C, 5 g/L YE, and 20 g/L PEP, respectively. Nevertheless, the best fermentation parameters were 15 g/L IGC, 5% (v/v) IR, 5.5 IPV, 150 rpm SR, 30 °C T, no YE, and 5 g/L of PEP, respectively. At these conditions, kinetic results including bioethanol production, YP/S, ethanol yield per biomass, maximum production rate, sugar utilization yield, and theoretical YP/S were 8.29 g/L, 47.26%, 5.08 g ethanol/g biomass, 0.41 g/L/h, 95.86%, and 92.49%, respectively. In conclusion, these results indicated that although the concentrations of ingredients (YE and PEP) used in the fermentation medium were considerably decreased from 10 and 20 g/L to 0 and 5 g/L, the kinetic results of the fermentation were preserved compared to the initial fermentation studies. Nevertheless, further improvement of the determined fermentation parameters could be performed in the bioreactor. [ABSTRACT FROM AUTHOR]

Using wheat B starch as raw material, optimize the one-step enzymatic hydrolysis process for preparing fermentable sugars and subsequent fermentation of alcohol by brewing yeast to improve its utilization value. Initially, the elemental composition of Wheat B starch was quantified. A composite enzymatic catalyst containing α-amylase and saccharase were then employed to generate fermentable sugars from wheat B starch through enzymatic hydrolysis efficiently. Various parameters, including composite enzyme concentration, solid-liquid ratio, enzyme temperature, enzymatic duration, and pH were thoroughly investigated to assess their effects on reducing sugar yield. An orthogonal optimization approach was conducted to determine the optimal conditions for enzymatic hydrolysis. Results showed that wheat B starch contained 85.61% starch, with approximately 2% protein and mineral content, and pentosan composition nearing 5%. Following the orthogonal optimization, the most effective parameters for enzymatic saccharification were identified: A composite enzyme dosage of 4 mL, a solid-liquid ratio of 1:25 g/mL, an enzymatic digestion temperature of 60 ℃, an enzymatic digestion duration of 10 h, and a pH of 5.0. Under these specific conditions, the yield of reducing sugar reached 94.6%. Subsequently, wheat B starch was converted into alcohol through yeast-mediated fermentation. This process led to a final alcohol concentration 12.76 g/L, accompanied by an alcohol yield of 31.90%. In conclusion, wheat B starch holded remarkable promise for large-scale bioethanol production, providing valuable insights for maximizing the utilization of this resource on a broad scale.

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]

Copyright of Science & Technology of Food Industry is the property of Science & Technology of Food Industry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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 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]

A method was proposed to enhance the growth of Saccharomyces cerevisiae cells and increase the alcohol yield. This strategy utilized nanozymes, specifically FeCo-Prussian blue analogue nanoparticles (FeCo-PBA NPs), FeCo-N-C, CoSO porous nanocubes (CoSO PNCs), and FeN3P-single-atom nanozymes (FeN3P-SAzyme), to mimic the antioxidant enzymes. When subjected to H2O2 stress, the nanozymes significantly stimulated cell growth and effectively reduced the levels of reactive oxygen species (ROS), as evidenced by the decrease in the malondialdehyde (MDA) content. Additionally, the decline in lactate dehydrogenase (LDH) activity within the fermentation environment suggested that nanozymes provided protection against cell membrane damage caused by H2O2. This protective effect can be attributed to their inhibitory impact on ROS production. Further results demonstrated that 50 μg mL–1 of nanozymes led to an increase in the ethanol yield and total alcohol yield in S. cerevisiae. This approach held great potential for enhancing alcohol production efficiency in the S. cerevisiae industrial fermentation process. [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]

One of the challenges in biofuel production from lignocellulosic wastes is to improve its conversion to solvents; therefore, new strategies to enhance xylose uptake are required due to be the secondary abundant sugar. In this context, a novel fermentation strategy integrating a co-culture of Clostridium acetobutylicum and Saccharomyces cerevisiae with pH control was developed. Initially, two different buffers, ammonium acetate and calcium carbonate, were tested under pHmin > 4.8 by fermenting 60 g L−1 of glucose with the C. acetobutylicum monoculture. Ammonium acetate was selected for fermenting media as butanol production was increased from 9.8 to 10.9 g L−1 over the calcium carbonate test. Comparing with the spontaneous acetone-butanol-ethanol (ABE) fermentation with C. acetobutylicum when no xylose consumption was observed, xylose consumption was efficiently increased by controlling pHmin > 4.8. The xylose consumption was > 47% either by using a 45:15 g L−1 glucose:xylose mixture or with rice straw (RS) hydrolysate. Clostridium monoculture using RS hydrolysate and pHmin > 4.8 produced a butanol (ABE) concentration of 6.5 (9.5) g L−1. While it increased to 7.0 (13.1) g L−1 when the co-culture with S. cerevisiae was used using same pH regulation strategy mainly due to ethanol increase up to 2.7 g L−1. Moreover, the xylose uptake doubled to 94% due to amino-acid secretion by yeast. Overall, this combined strategy was a very effective method for promoting sugar consumption and ABE solvent production from lignocellulosic waste. [ABSTRACT FROM AUTHOR]

Copyright of Food & Fermentation Industries is the property of Food & Fermentation Industries and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The use of renewable feedstocks and the variability of lignocellulosic feedstocks generating fermentable sugars also offer the advantages of the most abundant, sustainable and competitive non-food biomass. The aim of this study is to valorize the oilcake obtained from non-conventional Congolese Afzelia bella oilseeds, after extraction of the oil used in biodiesel production. The conversion of A. bella oilseeds cake into ethanol was carried out using the two methods of pretreatment (with the synthesized ionic liquid 1-butyl-3-methyl imidazolium chloride and dilute sulfuric acid), followed by hydrolysis with dilute sulfuric acid and fermentation by Saccharomyces cerevisiae. The lignocellulosic composition of the sample was 47.98% cellulose, 28.15% hemicellulose and 22.3% lignin. Pretreatment with 1-butyl-3-methyl-imidazolium chloride (ionic liquid) showed an increase in cellulose content of around 4.25% and hemicellulose content of around 7.7%, with simultaneous delignification of 12.25%. In contrast, with dilute sulfuric acid, the lignin and cellulose content of the sample fell to 3.88% and 1.88% respectively. Hemicellulose content, on the other hand, increased by only 3.58%. After dilute acid hydrolysis (5% H2SO4), the values for total reducing sugar, glucose and xylose were 66.06±1.34 mg.g-1; 36.25 ± 1.2 mg.g-1 and 29.71 ± 0.6 mg.g-1 respectively. The percentage conversion of sugars was 55.16 ± 0.5% for cellulose to glucose and 53.76 ± 0.75% for hemicellulose to xylose. The hydrolyzed product of the complex polysaccharide was then converted to ethanol using commercial yeast. Results showed an ethanol yield of around 10.3%, and Fourier Transform Infrared (FTIR) spectroscopy results confirmed bioethanol production. A. bella oilseeds cakes are therefore a potential source for ethanol production.

Background Cayratia trifolia has been extensively studied for its bioactive components and medicinal properties. This study was carried out to evaluate the fermentation ability of Saccharomyces cerevisiae 2.1 yeast to determine suitable fermentation conditions. Methods The initial sugar content for three-leaf cayratia fermentation and fermentation efficiency were calculated. The temperature for three-leaf cayratia fermentation, incubation time, and preliminary 1 liter of three-leaf cayratia wine fermentation were determined. All treatments showed that the total sugar content decreased after 9 days of fermentation compared to the initial level. Temperature during fermentation has a direct effect on yeast activity. Temperature increases the growth of yeast and speed of enzyme activity. The fermentation time changes depending on temperature, initial soluble solid contents, and yeast strains, leading to changes in the ethanol content after the end of fermentation. Results The results showed that the S. cerevisiae 2.1 was able to ferment at room temperature with an initial pH of 4.5, 24 °Brix, and a yeast density of 107 cells/mL. The appropriate fermentation conditions determined for S. cerevisiae 2.1 were 24 °Brix and incubation at room temperature (28-33°C) with a fermentation time of 11 days. Concusion In 1-L scale fermentation, three-leaf cayratia wine had 9.46% (v/v) and the fermentation efficiency was 90.34%. The wine produced had a unique color, flavor, and aroma that met the sensory evaluation of the Vietnamese national standard TCVN-3217:79.

Mycotoxins (ochratoxin A (20 ppb), aflatoxin B1 (40 ppb), deoxynivalenol (4 ppm), and zearalenone (800 ppb)) were intentionally added to rice bran raw materials. After fermentation, their contents were determined in the distillate and distillery stillage obtained using single-stage and continuous pilot plant-scale columns. After single-stage distillation, aflatoxin B1, deoxynivalenol, and zearalenone were not detected in the distillate, indicating that even if a certain amount (four times the maximum residue limit (MRL)) was present in the raw material, it would not remain in the distillate after fermentation and distillation. Most mycotoxins remained in the distillery stillage, and their residual rates ranged from 54.0–96.2%. For ochratoxin A, 0.19 ppb was found in the distillate and this migration occurred in three consecutive distillations (0.11–0.22 ppb). Ochratoxin A and aflatoxin B1 were not detected in the distillate (alcohol content 93.9% and 95.4%, respectively) obtained from the contaminated fermented liquid (approximately three times the MRL based on the raw material) using the pilot-plant scale continuous distillation column. Therefore, the migration of mycotoxins is difficult when the distilled spirit is produced using a continuous distillation column, even if the raw material is contaminated with certain amounts of the investigated mycotoxins. [ABSTRACT FROM AUTHOR]

Background: Cayratia trifolia has been extensively studied for its bioactive components and medicinal properties. This study was carried out to evaluate the fermentation ability of Saccharomyces cerevisiae 2.1 yeast to determine suitable fermentation conditions. Methods: The initial sugar content for three-leaf cayratia fermentation and fermentation efficiency were calculated. The temperature for three-leaf cayratia fermentation, incubation time, and preliminary 1 liter of three-leaf cayratia wine fermentation were determined. All treatments showed that the total sugar content decreased after 9 days of fermentation compared to the initial level. Temperature during fermentation has a direct effect on yeast activity. Temperature increases the growth of yeast and speed of enzyme activity. The fermentation time changes depending on temperature, initial soluble solid contents, and yeast strains, leading to changes in the ethanol content after the end of fermentation. Results:The results showed that the S. cerevisiae 2.1 strain was able to ferment at room temperature with an initial pH of 4.5, 24 °Brix, and a yeast density of 107 cells/mL. The appropriate fermentation conditions determined for S. cerevisiae 2.1 yeast were 24 °Brix and incubation at room temperature (28-33°C) with a fermentation time of 11 days. Concusion: In 1 liter scale fermentation, three-leaf cayratia wine had 9.46% (v/v) and the fermentation efficiency was 90.34%. The wine produced had a unique color, flavor, and aroma that met the sensory evaluation of the Vietnamese standard TCVN-3217:79.

The complex structure of rice straw is such that its bioconversion requires multiple physical and chemical pretreatment steps. In this study, it was found that a large amount of soluble polysaccharides (SPs) are formed during the pretreatment of straw. The yield of NaOH-based SPs (4.8%) was much larger than that of ball-milled SPs (1.5%) and H2SO4-based SPs (1.1%). For all the pretreatments, the ratio of phenolic compounds to saccharides (P/S) for each type of SPs increased upon increasing the concentration of ethanol in the order of 90% > 70% > 50%. The yield of NaOH-based SPs was much higher than that of acid-based and ball-milled SPs. The changes in the 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS), ferric reducing antioxidant power assay (FRAP), and 2,2-diphenyl-1-picrylhydrazyl (DPPH) of SPs follow the same rule, i.e., the higher the P/S ratio, the higher the antioxidant values of the SPs. The flow cytometry and laser scanning microscopy results show that the P/S ratio can significantly influence the effect of SPs on microbial growth and cell membrane permeability. Upon varying the ethanol concentration in the range of 50–90%, the P/S ratio increased from 0.02 to 0.17, resulting in an increase in the promoting effects of the SPs on yeast cell growth. Furthermore, H2O2, NAD+/NADH, and NADP+/NADPH assays indicate that SPs with a high P/S ratio can reduce intracellular H2O2 and change the intracellular redox status. [ABSTRACT FROM AUTHOR]

In this study, the primary paper-mill sludge characterized as containing 51% glucan was used to optimize the enzymatic saccharification process for the production of bioethanol using a Box–Behnken design (BBD). Polyethylene glycol 4000 (PEG-4000) surfactant-assisted enzymatic saccharification of dried primary sludge (DPS) showed a 12.8% improvement in saccharification efficiency. There was a statistically significant effect of solid enzyme loading and saccharification time on the enzymatic saccharification of DPS at a 95% confidence level (p < 0.05). The optimum levels of 10.4% w/w DPS solid loading, 2.03% enzyme loading (10 FPU g/DPS), and 1% (w/w DPS) PEG-4000 loading for a saccharification efficiency of 57.66% were validated experimentally and found to be non-significant with regard to the lack of fit with the predicted saccharification efficiency of 56.76%. Furthermore, Saccharomyces cerevisiae fermented the saccharified sugars into ethanol (9.35 g/L) with a sugar-to-ethanol conversion yield of 91.6% compared with the theoretical maximum. Therefore, DPS is a more suitable renewable biomass for determining the presence of fermentable sugar and for the production of ethanol. [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.

Ligusticum chuanxiong is a common traditional edible-medicinal herb that has various pharmacological activities. However, its effects on Saccharomyces cerevisiae (S. cerevisiae) remains unknown. In this study, we found that water extract of Ligusticum chuanxiong (abbreviated as WEL) exhibited excellent free radical scavenging ability in-vitro. Moreover, WEL treatment could delay the aging of S. cerevisiae, an important food microorganism sensitive to reactive oxygen species (ROS) stress. Biochemical analyses revealed that WEL significantly increased the activity of antioxidant enzymes in S. cerevisiae, including superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GR), as well as their gene expression. As a result, ROS level was significantly decreased and accompanied with the decline of malondialdehyde (MDA), which represented a state of low oxidative stress. The reduction of oxidative stress could elevate S. cerevisiae's ethanol fermentation efficiency. Taken together, WEL plays a protective role against S. cerevisiae aging via improving antioxidant activity.

Eucheuma denticulatum is a red macroalgae with a high carbohydrate content. The fermentable sugars from E. denticulatum were obtained through sequential thermal acid hydrolysis, enzymatic saccharification, and detoxification. Thermal acid hydrolysis of E. denticulatum was optimized under the condition of 10% (w/v) slurry content and 300 mM HNO3 at 121 ℃ for 90 min. The maximum monosaccharide concentration after thermal acid hydrolysis was 31.0 g/L with an efficiency (ETAH) of 44.7%. By further enzymatic hydrolysis of pretreated biomass solution under 20 U/mL Cellic CTec2 at 50 ℃ and 160 rpm for 72 h, the maximum monosaccharide concentration reached 79.9 g/L with an efficiency of 66.2% (ES). To remove 5-hydroxymethylfurfural (5-HMF), a fermentation inhibitor, absorption using 2% activated carbon was performed for 2 min. Ethanol fermentation was performed using wild-type and high galactose-adapted strains of Saccharomyces cerevisiae, Kluyveromyces marxianus, and Candida lusitaniae. As a result, galactose-adapted strains showed higher ethanol production than wild-type strains. Especially, the fermentation result by adaptively evolved S. cerevisiae produced the highest ethanol of 37.6 g/L and with YEtOH of 0.48 g/g. Moreover, the transcript level of MIG1 in the galactose-adapted strain was slightly lower than that in the wild-type strain. The application of adaptive evolution of microorganisms was efficient for bioethanol production. [ABSTRACT FROM AUTHOR]

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

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

The Sugar industry faces several sustainability challenges due to dumping of excess global production which cause stiff competition for high cost sugar producers like Kenya. Through diversification into cogeneration and ethanol production, sugar companies in high cost producing countries can remain competitive and survive in the market. In this study, the technical and economic feasibility of ethanol production is done for the case of Nzoia Sugar Company in Kenya whose milling capacity is 3000 tons of cane per day (TCD). Molasses is taken through a series of stages starting with pretreatment, followed by fermentation and distillation to produce ethanol. The ethanol formed is then transferred to the distillation columns for fractionation to remove water and hence have ethanol rich product. Through further distillation and molecular sieve dehydration the purity and quality of the final ethanol product is enhanced. The main equipment for the process includes the fermenter, boilers, condensers, and distillation columns, design to suit the product characteristics and design capacity of the plant. The analysis showed that ethanol production by a 3000 TCD sugar factory is a profitable venture. The study showed that investment is both technically and economically feasible and will improve the financial performance and sustainability of the sugar factory in a competitive market environment. Therefore, diversification into ethanol production is an important strategy in sustaining the sugar industry in a competitive global market.

The soluble and fermentable carbohydrate contents was detected over 47% of glucose and fructose in Chinese Elaeagnus angustifolia fruit powder (EAF), being over 47 wt% sugar content more than that of grape. Ethanol was therefore fermented directly from EAF, and different submerged fermentation modes were comparatively employed to optimize ethanol harvest. The results indicated that glucose has certain competitive inhibition on fructose bio-utilization, as well as the EAF solid residue involved fermentation mode also hindered the fermented-ethanol titer. Pectinase addition and in situ hydrolysis seemed to assist somewhat the fermentation. The water-solute fermentation mode is preferable, and glucose and fructose components were completely consumed and converted to 80.96 g/L ethanol at 87.6% ethanol yield even under tannin and pectin inhibition. The fermentation result could provide some experimental data and an approach to not only new biomass resource explores of bioethanol and alcohol beverage production, but also the technological development on valorization commercials of EAF in global draught areas. [ABSTRACT FROM AUTHOR]

Wood biomass conversion for fossil resource replacement could result in the sustainable production of chemicals, although lignin represents an obstacle to efficient polysaccharide use. White-rot fungus Phlebia sp. MG-60 reportedly selectively and aerobically degrades lignin in hardwood, then it begins cellulose saccharification from the delignified wood to produce ethanol. Environmental conditions might change white-rot fungi-driven biomass conversion. However, how the environmental response sensor affects ethanol fermentation in white-rot fungi remains elusive. In this study, we focused on MGHOG1, the yeast Hog1 homolog in Phlebia sp. MG-60, a presumably important player in osmoresponse. We generated MGHOG1 overexpressing (OE) transformants in Phlebia sp. MG-60, exhibiting slower mycelial growth compared with the wild-type under salinity stress. MGHOG1 overexpressing liquid cultures displayed suppressed mycelial growth and ethanol fermentation. Therefore, MGHOG1 potentially influences ethanol fermentation and mycelial growth in Phlebia sp. MG-60. This study provides novel insights into the regulation of white-rot fungi-mediated biomass conversion. [ABSTRACT FROM AUTHOR]

As a flooding-tolerant tree species, Taxodium distichum has been utilized in afforestation projects and proven to have important value in flooding areas. Alcohol dehydrogenase (ADH), which participates in ethanol fermentation, is essential for tolerance to the anaerobic conditions caused by flooding. In a comprehensive analysis of the ADH gene family in T. distichum, TdADHs were cloned on the basis of whole-genome sequencing, and then bioinformatic analysis, subcellular localization, and gene expression level analysis under flooding were conducted. The results show that the putative protein sequences of 15 cloned genes contained seven TdADHs and eight TdADH-like genes (one Class III ADH included) that were divided into five clades. All the sequences had an ADH_N domain, and except for TdADH-likeE2, all the other genes had an ADH_zinc_N domain. Moreover, the TdADHs in clades A, B, C, and D had a similar motif composition. Additionally, the number of TdADH amino acids ranged from 277 to 403, with an average of 370.13. Subcellular localization showed that, except for TdADH-likeD3, which was not expressed in the nucleus, the other genes were predominantly expressed in both the nucleus and cytosol. TdADH-likeC2 was significantly upregulated in all three organs (roots, stems, and leaves), and TdADHA3 was also highly upregulated under 24 h flooding treatment; the two genes might play key roles in ethanol fermentation and flooding tolerance. These findings offer a comprehensive understanding of TdADHs and could provide a foundation for the molecular breeding of T. distichum and current research on the molecular mechanisms driving flooding tolerance. [ABSTRACT FROM AUTHOR]

Mycotoxins (ochratoxin A (20 ppb), aflatoxin B1 (40 ppb), deoxynivalenol (4 ppm), and zearalenone (800 ppb)) were intentionally added to rice bran raw materials. After fermentation, their contents were determined in the distillate and distillery stillage obtained using single-stage and continuous pilot plant-scale columns. After single-stage distillation, aflatoxin B1, deoxynivalenol, and zearalenone were not detected in the distillate, indicating that even if a certain amount (four times the maximum residue limit (MRL)) was present in the raw material, it would not remain in the distillate after fermentation and distillation. Most mycotoxins remained in the distillery stillage, and their residual rates ranged from 54.0–96.2%. For ochratoxin A, 0.19 ppb was found in the distillate and this migration occurred in three consecutive distillations (0.11–0.22 ppb). Ochratoxin A and aflatoxin B1 were not detected in the distillate (alcohol content 93.9% and 95.4%, respectively) obtained from the contaminated fermented liquid (approximately three times the MRL based on the raw material) using the pilot-plant scale continuous distillation column. Therefore, the migration of mycotoxins is difficult when the distilled spirit is produced using a continuous distillation column, even if the raw material is contaminated with certain amounts of the investigated mycotoxins.

Background: Cayratia trifolia has been extensively studied for its bioactive components and medicinal properties. This study was carried out to evaluate the fermentation ability of Saccharomyces cerevisiae 2.1 yeast to determine suitable fermentation conditions. Methods: The initial sugar content for three-leaf cayratia fermentation and fermentation efficiency were calculated. The temperature for three-leaf cayratia fermentation, incubation time, and preliminary 1 liter of three-leaf cayratia wine fermentation were determined. All treatments showed that the total sugar content decreased after 9 days of fermentation compared to the initial level. Temperature during fermentation has a direct effect on yeast activity. Temperature increases the growth of yeast and speed of enzyme activity. The fermentation time changes depending on temperature, initial soluble solid contents, and yeast strains, leading to changes in the ethanol content after the end of fermentation. Results: The results showed that the S. cerevisiae 2.1 strain was able to ferment at room temperature with an initial pH of 4.5, 24 °Brix, and a yeast density of 107 cells/mL. The appropriate fermentation conditions determined for S. cerevisiae 2.1 yeast were 24 °Brix and incubation at room temperature (28-33°C) with a fermentation time of 11 days. Concusion: In 1 liter scale fermentation, three-leaf cayratia wine had 9.46% (v/v) and the fermentation efficiency was 90.34%. The wine produced had a unique color, flavor, and aroma that met the sensory evaluation of the Vietnamese standard TCVN-3217:79.

Direct reutilization of condensate can inhibit ethanol fermentation, 2-phenylethyl alcohol and furfural existed in the condensate are considered to be inhibitors. To achieve the reutilization of the condensate, the ozonation combined with ion-exchange method was used. The results showed that the elimination rates of 2-phenylethyl alcohol and furfural reached 98.0% and 100.0%, respectively after ozonation, while the concentrations of acetic acid, propionic acid, butyric acid and valeric acid increased by 14.9%, 7.7%, 35.3% and 25.5%, respectively. The fermentation results showed that the inhibition of the condensate after ozonation was alleviated but was not completely eliminated. When the effluent volume treated by the ion-exchange method reached 80 BV, the concentrations of acetic acid, propionic acid, butyric acid and valeric acid decreased by 25.8%, 8.6%, 6.5% and 34.4%, respectively. The fermentation results showed that the inhibition of the condensate was completely eliminated after ozonation combined with ion-exchange treatment. [ABSTRACT FROM AUTHOR]

In this study, various mathematical functions were utilized to fit the observed values and the kinetic parameters of fermentation in immobilized-cell stirred tank reactor (ICSTR) with carob extract medium (CEM). The best model was selected based on the residual sum of squares (RSS), root-mean-square-error (RMSE), mean-absolute-error (MAE), determination coefficient (R2), slope (m), bias factor (BF), accuracy factor (AF), the objective function (Φ-factor), and f-testing. Therefore, the Stannard (ST) model was good agreement with the actual biomass production (X), ethanol production (P), and sugar consumption (S) data (RSS = 0.22, 6.23, and 45.70 g/L; RMSE = 0.17, 0.88, and 2.39 g/L; MAE = 0.14, 0.64, and 1.72 g/L; R2 = 0.9948, 0.9977, and 0.9972; m = 1.03, 1.02, and 1.02; BF = 1.35, 1.08, and 0.97; AF = 1.41, 1.14, and 1.04; and Φ-factor = 0.008, 0.004, and 0.005 (∑Φ-factor = 0.017) for X, P, and S, respectively). In the prediction of kinetic parameters belonging to the experimental fermentation, the ST model also gave better, satisfactory, and well-directed results than the other mathematical models. Besides, the ST model was also accomplishedly validated using two independent sets of the experimental data yielded from the different carbon sources in various concentrations. Consequently, the models proposed for X, P, and S can serve as universal functions to predict the real values and the kinetic parameters of the ethanol fermentation. Besides, these models can be applied to improve the ethanol fermentation in the ICSTR with CEM. [ABSTRACT FROM AUTHOR]

Introduction. Recent studies have shown the benefits of phytolytic enzymes to prepare grain wort in ethanol production. However, there is a lack of data on the effect of phytases and their amount on the conversion of grain polymers, the ionic composition of wort and mash, and the efficiency of yeast generation and ethanol fermentation. Study objects and methods. Wheat and corn wort samples were treated with a complex of hydrolases, including phytases. Capillary electrophoresis determined the ionic composition of wort and mash. Gas chromatography measured the content of volatile metabolites. Results and discussion. The key enzymes were phytases and proteases. They improved the conversion of grain polymers and stimulated the growth and metabolism of yeast cells. Their synergism enriched the wort with assimilable nitrogen, phosphorus, and other valuable minerals. In addition, it intensified the growth of the Saccharomyces cerevisiae yeast, increased the rate of carbohydrate consumption, and reduced the formation of side metabolites 1.7–1.9 times, mainly due to higher and aromatic alcohols. The concentration of phosphates remained practically unchanged during the fermentation of grain wort treated with phytases. However, by the end of fermentation, it was 2.4–5.1 times higher than in the mash samples without phytolytic treatment. Finally, we identified a complex of enzymes and optimal amounts of phytases that have a stimulating effect on ethanol fermentation. Conclusion. Phytases, whether used individually or together with proteases, enriched grain wort with soluble macro- and microelements, improved yeast metabolism, directed ethanol synthesis, and decreased the formation of fermentation by-products.

Abstract Background As one of the clean and sustainable energies, lignocellulosic ethanol has achieved much attention around the world. The production of lignocellulosic ethanol does not compete with people for food, while the consumption of ethanol could contribute to the carbon dioxide emission reduction. However, the simultaneous transformation of glucose and xylose to ethanol is one of the key technologies for attaining cost-efficient lignocellulosic ethanol production at an industrial scale. Genetic modification of strains and constructing consortia were two approaches to resolve this issue. Compared with strain improvement, the synergistic interaction of consortia in metabolic pathways should be more useful than using each one separately. Results In this study, the consortia consisting of suspended Scheffersomyces stipitis CICC1960 and Zymomonas mobilis 8b were cultivated to successfully depress carbon catabolite repression (CCR) in artificially simulated 80G40XRM. With this strategy, a 5.52% more xylose consumption and a 6.52% higher ethanol titer were achieved by the consortium, in which the inoculation ratio between S. stipitis and Z. mobilis was 1:3, compared with the Z. mobilis 8b mono-fermentation. Subsequently, one copy of the xylose metabolic genes was inserted into the Z. mobilis 8b genome to construct Z. mobilis FR2, leading to the xylose final-consumption amount and ethanol titer improvement by 15.36% and 6.81%, respectively. Finally, various corn stover hydrolysates with different sugar concentrations (glucose and xylose 60, 90, 120 g/L), were used to evaluate the fermentation performance of the consortium consisting of S. stipitis CICC1960 and Z. mobilis FR2. Fermentation results showed that a 1.56–4.59% higher ethanol titer was achieved by the consortium compared with the Z. mobilis FR2 mono-fermentation, and a 46.12–102.14% higher ethanol titer was observed in the consortium fermentation when compared with the S. stipitis CICC1960 mono-fermentation. Furthermore, qRT-PCR analysis of xylose/glucose transporter and other genes responsible for CCR explained the reason why the initial ratio inoculation of 1:3 in artificially simulated 80G40XRM had the best fermentation performance in the consortium. Conclusions The fermentation strategy used in this study, i.e., using a genetically modified consortium, had a superior performance in ethanol production, as compared with the S. stipitis CICC1960 mono-fermentation and the Z. mobilis FR2 mono-fermentation alone. This result showed that this strategy has potential for future lignocellulosic ethanol production.

Online monitoring of fermentation processes is a necessary task to determine concentrations of key biochemical compounds, diagnose faults in process operations, and implement feedback controllers. However, obtaining the signals of all-important variables in a real process is a task that may be difficult and expensive due to the lack of adequate sensors, or simply because some variables cannot be directly measured. From the above, a model-based approach such as state observers may be a viable alternative to solve the estimation problem. This work shows a comparative analysis of the real-time performance of a family of sliding-mode observers for reconstructing key variables in a batch bioreactor for fermentative ethanol production. These observers were selected for their robust performance under model uncertainties and finite-time estimation convergence. The selected sliding-mode observers were the first-order sliding mode observer, the proportional sliding mode observer, and the high-order sliding mode observer. For estimation purposes, a power law kinetic model for ethanol production by Saccharomyces cerevisiae was performed. A hybrid methodology allows the kinetic parameters to be adjusted, and an approach based on inference diagrams allows the observability of the model to be determined. The experimental results reported here show that the observers under analysis were robust to modeling errors and measurement noise. Moreover, the proportional sliding-mode observer was the algorithm that exhibited the best performance. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Bioprocess Engineering is the property of Chinese Journal of Bioprocess Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Simple Summary: Pyruvate decarboxylase (PDC) is a key enzyme involved in ethanol fermentation, a process for the production of biofuels. Thermostable and oxygen-stable PDC activity is highly desirable for biotechnological applications at high temperatures. The enzymes from the thermoacidophiles Saccharolobus (formerly Sulfolobus) solfataricus (Ss, Topt = 80 °C) and Sulfolobus acidocaldarius (Sa, Topt = 80 °C) were purified and characterized, and their biophysical and biochemical properties were determined comparatively. The purified enzymes were CoA-dependent and thermostable. There was no loss of activity in the presence of oxygen. In conclusion, both thermostable SsPDC and SaPDC catalyze the CoA-dependent production of acetaldehyde from pyruvate in the presence of oxygen. Pyruvate decarboxylase (PDC) is a key enzyme involved in ethanol fermentation, and it catalyzes the decarboxylation of pyruvate to acetaldehyde and CO2. Bifunctional PORs/PDCs that also have additional pyruvate:ferredoxin oxidoreductase (POR) activity are found in hyperthermophiles, and they are mostly oxygen-sensitive and CoA-dependent. Thermostable and oxygen-stable PDC activity is highly desirable for biotechnological applications. The enzymes from the thermoacidophiles Saccharolobus (formerly Sulfolobus) solfataricus (Ss, Topt = 80 °C) and Sulfolobus acidocaldarius (Sa, Topt = 80 °C) were purified and characterized, and their biophysical and biochemical properties were determined comparatively. Both enzymes were shown to be heterodimeric, and their two subunits were determined by SDS-PAGE to be 37 ± 3 kDa and 65 ± 2 kDa, respectively. The purified enzymes from S. solfataricus and S. acidocaldarius showed both PDC and POR activities which were CoA-dependent, and they were thermostable with half-life times of 2.9 ± 1 and 1.1 ± 1 h at 80 °C, respectively. There was no loss of activity in the presence of oxygen. Optimal pH values for their PDC and POR activity were determined to be 7.9 and 8.6, respectively. In conclusion, both thermostable SsPOR/PDC and SaPOR/PDC catalyze the CoA-dependent production of acetaldehyde from pyruvate in the presence of oxygen. [ABSTRACT FROM AUTHOR]

Kinases modulate the various physiological activities of microbial fermenting strains including the conversion of lignocellulose-derived phenolic aldehydes (4-hydroxyaldehyde, vanillin, and syringaldehyde). Here, we comprehensively investigated the gene transcriptional profiling of the kinases under the stress of phenolic aldehydes for ethanologenic Zymomonas mobilis using DNA microarray. Among 47 kinase genes, three genes of ZMO0003 (adenylylsulfate kinase), ZMO1162 (histidine kinase), and ZMO1391 (diacylglycerol kinase), were differentially expressed against 4-hydroxybenzaldehyde and vanillin, in which the overexpression of ZMO1162 promoted the phenolic aldehydes conversion and ethanol fermentability. The perturbance originated from plasmid-based expression of ZMO1162 gene contributed to a unique expression profiling of genome-encoding genes under all three phenolic aldehydes stress. Differentially expressed ribosome genes were predicted as one of the main contributors to phenolic aldehydes conversion and thus finally enhanced ethanol fermentability for Z. mobilis ZM4. The results provided an insight into the kinases on regulation of phenolic aldehydes conversion and ethanol fermentability for Z. mobilis ZM4, as well as the target object for rational design of robust biorefinery strains. [ABSTRACT FROM AUTHOR]

Abstract Background The industrial production of various alcohols from organic carbon compounds may be performed at high rates and with a low risk of contamination using thermophilic microorganisms as whole-cell catalysts. Thermoanaerobacter species that thrive around 50–75 °C not only perform fermentation of sugars to alcohols, but some also utilize different organic acids as electron acceptors, reducing them to their corresponding alcohols. Results We purified AdhE as the major NADH- and AdhB as the major NADPH-dependent alcohol dehydrogenase (ADH) from the cell extract of the organic acid-reducing Thermoanaerobacter sp. strain X514. Both enzymes were present in high amounts during growth on glucose with and without isobutyrate, had broad substrate spectra including different aldehydes, with high affinities (

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

This study proposed a recyclable p-toluenesulfonic acid (p-TsOH) fractionation process for co-producing lignin nanoparticles (LNPs) and fermentable sugars from lignocellulosic biorefinery biowaste (enzymatic hydrolysis residue (EHR)). The prepared LNPs were used to detoxify the inhibitors in the xylose-rich prehydrolyzate for improving ethanol production. Results showed that the EHR was fractionated into a cellulose-rich water-insoluble solid (WIS) fraction and a lignin-rich spent liquor (SL) fraction. Cellulase hydrolysis of WIS produced 97.7% of glucose yield, while the LNPs of an average particle size of 98.0 nm with 76.3 % yield (based on the untreated EHR) were obtained from the diluted SL. LNPs demonstrated higher detoxification ability than EHR at the same dosage. Moreover, the fermentability of the detoxified xylose-rich prehydrolyzate was significantly improved. The sugar utilization ratio was 94.8%, and the ethanol yield reached its peak value of 85.4% after 36 h of fermenting the detoxified xylose-rich prehydrolyzate. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Northwest A & F University - Natural Science Edition is the property of Editorial Department of Journal of Northwest A&F University (Natural Science Edition) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

For many biorefinery processes, the development of effective preservation techniques is essential to avoid any sugar loss between crop-harvesting and fermentation. In this work, five physicochemical techniques (acidification, ozonation, addition of sodium hydrosulfite, sodium sulfate and oil layer) were investigated for the preservation of sugar beet molasses diluted at low (150 g/L) and high (300 g/L) concentration of initial sugars. After 30 days, sugars and metabolites profiles were quantified to determine the optimal preservation technique capable of limiting the biological contamination while preserving as much fermentable sugars as possible. Although none of the strategies was efficient to prevent the microbial contamination at 150 g/L, some approaches allowed preserving more than 90% of fermentable sugars at 300 g/L of initial sugars. Furthermore, the use of 2 g/L of sodium hydrosulfite or acidifying the media to pH 3 allowed the conservation of nearly 100% of the fermentable sugars. Fermentation assays performed after storage indicated that acidification, sodium hydrosulfite and ozonation did not alter the fermentation performances, as the production of ethanol reached 102 g/L after 6 days of incubation. Therefore, the use of sodium hydrosulfite or acidification were considered as relevant strategies for maintaining fermentable sugars in liquid feedstock for bioethanol production. [Display omitted] • Diluted sugar beet molasses was used as feedstock for bioethanol production. • Five storage techniques were tested to preserve fermentable sugars from contamination. • Acidification or addition of Na 2 S 2 O 4 were the most efficient preservation techniques. • 90% of the initial fermentable sugars were preserved after 30 days of storage. • Addition of Na 2 S 2 O 4, acidification and ozonation did not impact the fermentation performances after storage. [ABSTRACT FROM AUTHOR]

Currently, most cotton textile waste is sent to landfill. However, due to the use of synthetic additives and the chemical treatment of cotton fibers, cotton textile waste is difficult to biodegrade. Cotton textile waste can also be subjected to material recycling, or to incineration/gasification to produce energy. Here, we present the optimization of acid hydrolysis of cotton yarn fibers for glucose efficiency. The cotton yarn hydrolysates showed great potential for replacing simple sugar solutions in fermentation media. The highest glucose concentration was obtained in the hydrolysates of cotton yarn hydrolyzed in a 2% solution of sulfuric acid or phosphoric acid at 140–160 °C for 2 h. After 2 h of hydrolysis at 140 °C with 2% H3PO4, the concentration of glucose in the cotton yarn hydrolysate (13.19 g/L) increased fivefold compared with cotton yarn treated under the same conditions with H2SO4 (2.65 g/L). The structural modifications in the solid residues after acid hydrolysis were analyzed using a scanning electron microscope with energy dispersive spectroscopy (SEM-EDS), attenuated total reflectance Fourier-transform infrared spectroscopy (FTIR-ATR), and Raman spectroscopy. The SEM images, IR spectra, and Raman spectra revealed that the most significant changes in the morphology of the fibers occurred when the process was carried out at high temperatures (≥140 °C). Better growth of the yeast strains Saccharomyces cerevisiae Ethanol Red and Saccharomyces cerevisiae Tokay ŁOCK0204 was observed in the medium containing phosphoric acid hydrolysate. The maximum methane yield of 278 dm3/kgVS and the maximum hydrogen yield of 42 dm/kgVS were reported for cotton yarn waste after pretreatment with H3PO4. This might have been linked to the beneficial effect of phosphorus, which is a key nutrient for anaerobic digestion. The proposed hydrolysis method does not generate fermentation inhibitors. [ABSTRACT FROM AUTHOR]

Thermotolerant ethanologenic yeasts have attracted the interest of many scientists due to the current challenges caused by increasing global temperature, the benefits associated with processing at high temperatures, and the potential to reduce cooling costs. The objectives of this study are to characterize the selected thermotolerant yeasts and to evaluate their use in Cayratia trifolia fermentation at high temperatures. A total of 151 yeast strains isolated from 53 samples of Cayratia trifolia were studied for their morphology, physiology, biochemistry, and their phylogenetic relationship. Based on the results of tests for thermotolerance ability (37-45oC) and ethanol tolerance capacity (9-12% v/v), 57 of the 151 yeast isolates were selected to be tested for use in wine fermentation from three-leaf cayratia at 37oC. Thirty isolates that were found to have high fermentation ability and that produced an ethanol concentration of between 6.0 and 9.9% (v/v) were selected for identification using amplified 26S rDNA sequences. The yeasts were identified as follows: Candida glabrata (BL2.1, CT1.1, CT1.3, CT2.3, HG2.1), Candida tropicalis (KG1.1, KG3.2, CM3.3, HG3.3, TG1.1, TG3.1), Candida nivariensis (DT1.2, CM3.2, ST2.1, BT1.2), Pichia kudriavzevii (KG2.1, KG5.1, AG2.1, AG2.3, AG4.2, DT3.2, LA1.3, CM4.4, BT2.1, BT3.3, TV4.2, CT4.2, VL1.1), Clavispora lusitaniae (TG4.2), and Saccharomyces cerevisiae (HG1.3). The phylogenetic tree constructed using MEGA 6 with bootstrap analysis performed by repeating the data 1,000 times revealed that the selected yeast strains were closely related. The newly isolated strain of S. cerevisiae HG1.3 producing the highest ethanol concentration of 9.9% (v/v) in Cayratia trifolia wine fermentation at 370C was selected for further study.

As a flooding-tolerant tree species, Taxodium distichum has been utilized in afforestation projects and proven to have important value in flooding areas. Alcohol dehydrogenase (ADH), which participates in ethanol fermentation, is essential for tolerance to the anaerobic conditions caused by flooding. In a comprehensive analysis of the ADH gene family in T. distichum, TdADHs were cloned on the basis of whole-genome sequencing, and then bioinformatic analysis, subcellular localization, and gene expression level analysis under flooding were conducted. The results show that the putative protein sequences of 15 cloned genes contained seven TdADHs and eight TdADH-like genes (one Class III ADH included) that were divided into five clades. All the sequences had an ADH_N domain, and except for TdADH-likeE2, all the other genes had an ADH_zinc_N domain. Moreover, the TdADHs in clades A, B, C, and D had a similar motif composition. Additionally, the number of TdADH amino acids ranged from 277 to 403, with an average of 370.13. Subcellular localization showed that, except for TdADH-likeD3, which was not expressed in the nucleus, the other genes were predominantly expressed in both the nucleus and cytosol. TdADH-likeC2 was significantly upregulated in all three organs (roots, stems, and leaves), and TdADHA3 was also highly upregulated under 24 h flooding treatment; the two genes might play key roles in ethanol fermentation and flooding tolerance. These findings offer a comprehensive understanding of TdADHs and could provide a foundation for the molecular breeding of T. distichum and current research on the molecular mechanisms driving flooding tolerance.

Agricultural residues (e.g. corn stover (CS)) representing a huge lignocellulosic biomass waste are regarded as a promising renewable resource that can be converted to fuels and chemicals via biochemical route. Nevertheless, the unfavorable properties, such as low bulk density, contamination by microorganisms, fluffy and thereby difficult to handle, cause huge problems for biomass logistics and biomass conversion. Furthermore, traditional biomass pretreatment methods often use severe conditions, consume much energy, difficult to scale up and generate a feedstock with many toxic degradation products that inhibit fermentation. In this study, we developed a novel, low-cost and easy-to-implement pretreatment method: "Densifying Lignocellulosic biomass with acidic Chemicals (DLC)" on CS. The DLC-CS owning a uniform shape showed a bulk density 4 times higher compared to loose CS and was highly resistant to microbial contamination, which greatly facilitates biomass handling, transportation and storage. DLC-CS after regular steam autoclave treatment at 121 ○C exhibited high enzymatic digestibility and much higher fermentability compared to traditional dilute acid pretreatment. An ethanol titer as high as 68.1 g/L was achieved without washing or detoxification of the pretreated biomass. The superior performances of DLC for biomass logistics and biomass conversion render it very promising for industrial use. • A novel lignocellulosic biomass pretreatment method was developed. • This method increased biomass bulk density and prevented microbial contamination. • The pretreated biomass showed high digestibility and high fermentability. • A high ethanol titer (68.1 g/L) was achieved without washing or detoxification. • This method facilitates biomass logistics and greatly reduces pretreatment costs. [ABSTRACT FROM AUTHOR]

In this study, major factors involved in regulating ethanol production from wood by the saprotrophic white-rot fungus Phanerochaete sordida YK-624 were investigated. P. sordida YK-624 produced ethanol from wood meal culture without the addition of any nutrients, and ethanol was produced from wood culture only when the oxygen concentration in headspace was reduced to ≤5%; thereafter, ethanol production ceased within a few days. Analyses of gene expression during aerobic incubation indicated that P. sordida simultaneously upregulates the glycolytic pathway from sugar uptake to pyruvate conversion during ethanol fermentation and suppresses pyruvate influx into the TCA cycle. Upon termination of ethanol fermentation, the expression of all tested genes was repressed, and the fungus ceased to grow. In contrast, the fungus could utilize ethanol for aerobic growth. These results suggest that ethanol fermentation by P. sordida functions as a short-term stress response system under anaerobic conditions during wood decay, enabling the fungus to rapidly resume growing when oxygen is supplied (e.g., following breakdown of plant cell walls or removal of the fungus from water immersion). This is the first report to describe the physiologic significance of ethanol fermentation in saprotrophic white-rot fungi. [Display omitted] • The biological significance of ethanol fermentation by saprotrophic white-rot fungus P. sordida YK-624 was speculated. • P. sordida YK-624 produced ethanol from wood meal without addition of any nutrients under hypoxic condition. • P. sordida YK-624 could survive and ferment for only a few days under hypoxia conditions during wood decay. • Ethanol fermentation in P. sordida YK-624 appears to be a short-term hypoxia tolerance system. [ABSTRACT FROM AUTHOR]

The present study demonstrates the feasibility of a two-phase biorefinery process applied to waste substrates producing ethanol rich effluents. The process includes a dark fermentation step followed by photo fermentation and it is able to optimize hydrogen production from waste biomass. The study was conducted using winery wastewater as feedstock. The results indicate that no additional treatments are required when an appropriate dilution of the initial waste is applied. Microbial consortia contained in the winery wastewater promoted a fermentative ethanol pathway. The ethanol rich effluent was converted into hydrogen by phototrophic microorganisms. Despite the presence of inhibiting compounds, the adoption of a mixed phototrophic culture allowed to obtain good results in terms of hydrogen production. Specifically, up to 310 mLH 2 gCOD consumed −1 were obtained in the photo fermentative stage. The effectiveness of ethanol rich dark fermentation effluents for hydrogen production enhancement was demonstrated. Noteworthy, polyhydroxybutyrate was also produced during the experiments. The work faces two of the major challenges in the sequential dark fermentation and photo fermentation technology applied to real waste substrates: the minimization of pre-treatments and the enhancement of the hydrogen production yields using ethanol rich DFEs. [Display omitted] • A dark-photo fermentation process for winery wastewater treatment is proposed. • Indigenous cultures of winery wastewater promote the ethanol production pathway. • Dark fermentation intermediates define the photo fermentative hydrogen yield. • Ethanol rich dark fermentation effluents are effective substrates for PNSB. • Use of mixed PNSB cultures is beneficial to reduce pre-treatments. [ABSTRACT FROM AUTHOR]