Sample records for affects ethanolic fermentation

  1. Homo- and heterofermentative lactobacilli differently affect sugarcane-based fuel ethanol fermentation. (United States)

    Basso, Thiago Olitta; Gomes, Fernanda Sgarbosa; Lopes, Mario Lucio; de Amorim, Henrique Vianna; Eggleston, Gillian; Basso, Luiz Carlos


    Bacterial contamination during industrial yeast fermentation has serious economic consequences for fuel ethanol producers. In addition to deviating carbon away from ethanol formation, bacterial cells and their metabolites often have a detrimental effect on yeast fermentative performance. The bacterial contaminants are commonly lactic acid bacteria (LAB), comprising both homo- and heterofermentative strains. We have studied the effects of these two different types of bacteria upon yeast fermentative performance, particularly in connection with sugarcane-based fuel ethanol fermentation process. Homofermentative Lactobacillus plantarum was found to be more detrimental to an industrial yeast strain (Saccharomyces cerevisiae CAT-1), when compared with heterofermentative Lactobacillus fermentum, in terms of reduced yeast viability and ethanol formation, presumably due to the higher titres of lactic acid in the growth medium. These effects were only noticed when bacteria and yeast were inoculated in equal cell numbers. However, when simulating industrial fuel ethanol conditions, as conducted in Brazil where high yeast cell densities and short fermentation time prevail, the heterofermentative strain was more deleterious than the homofermentative type, causing lower ethanol yield and out competing yeast cells during cell recycle. Yeast overproduction of glycerol was noticed only in the presence of the heterofermentative bacterium. Since the heterofermentative bacterium was shown to be more deleterious to yeast cells than the homofermentative strain, we believe our findings could stimulate the search for more strain-specific antimicrobial agents to treat bacterial contaminations during industrial ethanol fermentation.

  2. Fermentation method producing ethanol (United States)

    Wang, Daniel I. C.; Dalal, Rajen


    Ethanol is the major end product of an anaerobic, thermophilic fermentation process using a mutant strain of bacterium Clostridium thermosaccharolyticum. This organism is capable of converting hexose and pentose carbohydrates to ethanol, acetic and lactic acids. Mutants of Clostridium thermosaccharolyticum are capable of converting these substrates to ethanol in exceptionally high yield and with increased productivity. Both the mutant organism and the technique for its isolation are provided.

  3. Yeast fermentation affected by homo- and hetero-fermentative Lactobacilli isolated from fuel ethanol distilleries with sugarcane products as substrates (United States)

    The antagonism between by yeast and lactobacilli is largely dependent on the initial population of each organism. While homo-fermentative lactobacillus present higher inhibitory effect upon yeast when in equal cell number, in industrial fuel ethanol conditions where high yeast cell densities prevail...

  4. Homo- and heterofermentative lactobacilli differently affect sugarcane-based fuel ethanol fermentation (United States)

    The antagonism between by yeast and lactobacilli is largely dependent on the initial population of each organism. While homo-fermentative lactobacillus present higher inhibitory effect upon yeast when in equal cell number, in industrial fuel ethanol conditions where high yeast cell densities prevail...

  5. Xylose fermentation to ethanol

    Energy Technology Data Exchange (ETDEWEB)

    McMillan, J.D.


    The past several years have seen tremendous progress in the understanding of xylose metabolism and in the identification, characterization, and development of strains with improved xylose fermentation characteristics. A survey of the numerous microorganisms capable of directly fermenting xylose to ethanol indicates that wild-type yeast and recombinant bacteria offer the best overall performance in terms of high yield, final ethanol concentration, and volumetric productivity. The best performing bacteria, yeast, and fungi can achieve yields greater than 0.4 g/g and final ethanol concentrations approaching 5%. Productivities remain low for most yeast and particularly for fungi, but volumetric productivities exceeding 1.0 g/L-h have been reported for xylose-fermenting bacteria. In terms of wild-type microorganisms, strains of the yeast Pichia stipitis show the most promise in the short term for direct high-yield fermentation of xylose without byproduct formation. Of the recombinant xylose-fermenting microorganisms developed, recombinant E. coli ATTC 11303 (pLOI297) exhibits the most favorable performance characteristics reported to date.

  6. Ethanol by continuous fermentation

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    EtOH is produced by continuous fermentation of molasses. Thus, molasses diluted to 20/sup 0/ Brix was inoculated with bakers' yeast and fermented at 32/sup 0/. When the medium reached 4% EtOH, it was circulated through a centrifuge. The concentrated yeast was recycled to the fermentor and the supernatant was sent to a still. After distillation, the still residue was returned to the fermentor. When the initial charge was entirely fermented, 13 kg molasses of 40/sup 0/ Brix was added to the fermentor per hour, and the yield of EtOH was 1.7 kg/100 L-hour.

  7. Fermentation of hexoses to ethanol

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    Gustafsson, Lena [Goeteborg Univ. (Sweden). Dept. of General and Marine Microbiology]|[Chalmers Univ. of Technology, Goeteborg (Sweden). Dept of Chemical Reaction Engineering


    The Goals of the project has been: to increase the ethanol yield by reducing the by-product formation, primarily biomass and glycerol, and to prevent stuck fermentations, i.e. to maintain a high ethanol production rate simultaneously with a high ethanol yield. The studies have been performed both in defined laboratory media and in a mixture of wood- and wheat hydrolysates. The yeast strains used have been both industrial strains of bakers yeast, Saccharomyces cerevisiae, and haploid laboratory strains. The Relevance of these studies with respect to production of ethanol to be used as fuel is explained by: With the traditional process design used today, it is very difficult to reach a yield of more than 90 % of the theoretical maximal value of ethanol based on fermented hexose. During 'normal' growth and fermentation conditions in either anaerobic batch or chemostat cultures, substrate is lost as biomass and glycerol in the range of 8 to 11 % and 6 to 11 % of the substrate consumed (kg/kg). It is essential to reduce these by-products. Traditional processes are mostly batch processes, in which there is a risk that the biocatalyst, i.e. the yeast, may become inactivated. If for example yeast biomass production is avoided by use of non-growing systems, the ethanol production rate is instantaneously reduced by at least 50%. Unfortunately, even if yeast biomass production is not avoided on purpose, it is well known that stuck fermentations caused by cell death is a problem in large scale yeast processes. The main reason for stuck fermentations is nutrient imbalances. For a good process economy, it is necessary to ensure process accessibility, i.e. to maintain a high and reproducible production rate. This will both considerably reduce the necessary total volume of the fermentors (and thereby the investment costs), and moreover minimize undesirable product fall-out.

  8. Sugar-rich sweet sorghum is distinctively affected by wall polymer features for biomass digestibility and ethanol fermentation in bagasse. (United States)

    Li, Meng; Feng, Shengqiu; Wu, Leiming; Li, Ying; Fan, Chunfen; Zhang, Rui; Zou, Weihua; Tu, Yuanyuan; Jing, Hai-Chun; Li, Shizhong; Peng, Liangcai


    Sweet sorghum has been regarded as a typical species for rich soluble-sugar and high lignocellulose residues, but their effects on biomass digestibility remain unclear. In this study, we examined total 63 representative sweet sorghum accessions that displayed a varied sugar level at stalk and diverse cell wall composition at bagasse. Correlative analysis showed that both soluble-sugar and dry-bagasse could not significantly affect lignocellulose saccharification under chemical pretreatments. Comparative analyses of five typical pairs of samples indicated that DP of crystalline cellulose and arabinose substitution degree of non-KOH-extractable hemicelluloses distinctively affected lignocellulose crystallinity for high biomass digestibility. By comparison, lignin could not alter lignocellulose crystallinity, but the KOH-extractable G-monomer predominately determined lignin negative impacts on biomass digestions, and the G-levels released from pretreatments significantly inhibited yeast fermentation. The results also suggested potential genetic approaches for enhancing soluble-sugar level and lignocellulose digestibility and reducing ethanol conversion inhibition in sweet sorghum.

  9. Effect of Propanoic Acid on Ethanol Fermentation by Saccharomyces cerevisiae in an Ethanol-Methane Coupled Fermentation Process

    Institute of Scientific and Technical Information of China (English)

    张成明; 杜风光; 王欣; 毛忠贵; 孙沛勇; 唐蕾; 张建军


    Propanoic acid accumulated in an ethanol-methane coupled fermentation process affects the ethanol fermentation by Saccharomyces cerevisiae. The effects of propanoic acid on ethanol production were examined in cassava mash under different pH conditions. Final ethanol concentrations increased when undissociated propanoic acid was 〈30.0 mmol·L-1 . Propanoic acid, however, stimulated ethanol production, as much as 7.6% under proper conditions, but ethanol fermentation was completely inhibited when undissociated acid was 〉53.2 mmol·L-1 . Therefore, the potential inhibitory effect of propanoic acid on ethanol fermentation may be avoided by controlling the undissociated acid concentrations through elevated medium pH. Biomass and glycerol production decreased with propanoic acid in the medium, partly contributing to increased ethanol concentration.

  10. Manufacturing Ethyl Acetate From Fermentation Ethanol (United States)

    Rohatgi, Naresh K.; Ingham, John D.


    Conceptual process uses dilute product of fermentation instead of concentrated ethanol. Low-concentration ethanol, extracted by vacuum from fermentation tank, and acetic acid constitutes feedstock for catalytic reaction. Product of reaction goes through steps that increases ethyl acetate content to 93 percent by weight. To conserve energy, heat exchangers recycle waste heat to preheat process streams at various points.

  11. Ethanolic fermentation of pentoses in lignocellulose hydrolysates

    Energy Technology Data Exchange (ETDEWEB)

    Hahn-Haegerdal, B.; Linden, T.; Senac, T.; Skoog, K. [Lund Univ. Chemical Center (Sweden)


    In the fermentation of lignocellulose hydrolysates to ethanol, two major problems are encountered: the fermentation of the pentose sugar xylose, and the presence of microbial inhibitors. Xylose can be directly fermented with yeasts; such as Pachysolen tannophilus, Candida shehatae, and Pichia stipis, or by isomerization of xylose to xylulose with the enzyme glucose (xylose) isomerase, and subsequent fermentation with bakers yeast, Saccharomyces cerevisiae. The direct fermentation requires low, carefully controlled oxygenation, as well as the removal of inhibitors. Also, the xylose-fermenting yeasts have a limited ethanol tolerance. The combined isomerization and fermentation with XI and S. cerevisiae gives yields and productivities comparable to those obtained in hexose fermentations without oxygenation and removal of inhibitors. However, the enzyme is not very stable in a lignocellulose hydrolysate, and S. cerevisiae has a poorly developed pentose phosphate shunt. Different strategies involving strain adaptation, and protein and genetic engineering adopted to overcome these different obstacles, are discussed.

  12. Ethanol fermentation in an immobilized cell reactor using Saccharomyces cerevisiae. (United States)

    Najafpour, Ghasem; Younesi, Habibollah; Syahidah Ku Ismail, Ku


    Fermentation of sugar by Saccharomyces cerevisiae, for production of ethanol in an immobilized cell reactor (ICR) was successfully carried out to improve the performance of the fermentation process. The fermentation set-up was comprised of a column packed with beads of immobilized cells. The immobilization of S. cerevisiae was simply performed by the enriched cells cultured media harvested at exponential growth phase. The fixed cell loaded ICR was carried out at initial stage of operation and the cell was entrapped by calcium alginate. The production of ethanol was steady after 24 h of operation. The concentration of ethanol was affected by the media flow rates and residence time distribution from 2 to 7 h. In addition, batch fermentation was carried out with 50 g/l glucose concentration. Subsequently, the ethanol productions and the reactor productivities of batch fermentation and immobilized cells were compared. In batch fermentation, sugar consumption and ethanol production obtained were 99.6% and 12.5% v/v after 27 h while in the ICR, 88.2% and 16.7% v/v were obtained with 6 h retention time. Nearly 5% ethanol production was achieved with high glucose concentration (150 g/l) at 6 h retention time. A yield of 38% was obtained with 150 g/l glucose. The yield was improved approximately 27% on ICR and a 24 h fermentation time was reduced to 7 h. The cell growth rate was based on the Monod rate equation. The kinetic constants (K(s) and mu(m)) of batch fermentation were 2.3 g/l and 0.35 g/lh, respectively. The maximum yield of biomass on substrate (Y(X-S)) and the maximum yield of product on substrate (Y(P-S)) in batch fermentations were 50.8% and 31.2% respectively. Productivity of the ICR were 1.3, 2.3, and 2.8 g/lh for 25, 35, 50 g/l of glucose concentration, respectively. The productivity of ethanol in batch fermentation with 50 g/l glucose was calculated as 0.29 g/lh. Maximum production of ethanol in ICR when compared to batch reactor has shown to increase

  13. Effect of multiple substrates in ethanol fermentations from cheese whey

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    Wang, C.J.; Jayanata, Y.; Bajpai, R.K.


    Ethanol fermentations from cheese whey by Kluyveromyces marxianus CBS 397 were investigated. Cheese whey, which contains lactose as the major sugar, has been found to have small amounts of glucose and galactose, depending on the source and operating conditions. Fermentation performance was strongly influenced by the presence of glucose and galactose. However, lactose did not significantly affect the cell growth and product formation even at a high concentration. A logistical model was proposed to take into account the effect of lactose. (Refs. 6).

  14. Batchwise ethanol fermentation with shochu distillery waste

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    Ueda, S.; Teramoto, Y.; Oba, R.; Ueki, T.; Kimura, K. (Kumamoto Institute of Technology, Kumamoto (Japan)); Shiota, S. (Tohi Jozo Co. Ltd., Kumamoto (Japan))


    In order to produce a shochu with a mild aroma, a new vacuum distillation precedure at low temperature of 35 to 40 centigrade was applied to shochu distillation. The resulting rice shochu distillery waste contained a large amount of viable yeast glucoamylase activity, acid protease activity, and neutral protease activity. About 10% of ethanol was produced in the fermented mash at 30 centigrade within three days. In contrast, distillery waste discharged by conventional distillation at high temperature of 55 to 60 centigrade could not be used for secondary ethanol fermentation at all. It was provided that the filtrate of secondarily-fermented distillery waste, which is containing ethanol and possessing a fine aroma fortified with higher alcohols and volatile esters during ethanol fermentation, can be useful for the production of a mirin-like liquor for cooking, Akazake,'' a characteristic red-colored, sweet alcoholic beverage produced in Kumamoto prefecture only, and a bath additive containing ethanol, a fine aroma, and enzymes. 15 refs, 2 figs., 3 tabs.

  15. Xylose fermentation to ethanol. A review

    Energy Technology Data Exchange (ETDEWEB)

    McMillan, J D


    The past several years have seen tremendous progress in the understanding of xylose metabolism and in the identification, characterization, and development of strains with improved xylose fermentation characteristics. A survey of the numerous microorganisms capable of directly fermenting xylose to ethanol indicates that wild-type yeast and recombinant bacteria offer the best overall performance in terms of high yield, final ethanol concentration, and volumetric productivity. The best performing bacteria, yeast, and fungi can achieve yields greater than 0.4 g/g and final ethanol concentrations approaching 5%. Productivities remain low for most yeast and particularly for fungi, but volumetric productivities exceeding 1.0 g/L-h have been reported for xylose-fermenting bacteria. In terms of wild-type microorganisms, strains of the yeast Pichia stipitis show the most promise in the short term for direct high-yield fermentation of xylose without byproduct formation. Of the recombinant xylose-fermenting microorganisms developed, recombinant E. coli ATTC 11303 (pLOI297) exhibits the most favorable performance characteristics reported to date.

  16. Improvement of ethanol fermentation under hyperbaric conditions. (United States)

    L'Italien, Y; Thibault, J; LeDuy, A


    Recently more and more interest is manifested in the utilization of high-pressure extraction using supercritical gases for the purification of products in biochemical processes. Some researchers have examined the possibility of circulating continuously a supercritical gas through the fermentor, under hyperbaric pressure, to recover the desired product while the fermentation is taking place. However, an earlier study has demonstrated that fermentation with baker's yeast was inhibited by a long exposure under hyperbaric pressure. This article is concerned with the improvement of ethanol production under hyperbaric pressure in view of the development of an integrated fermentation-extraction process where supercritical carbon dioxide would be used for the in situ recovery of ethanol. The selection of the best yeast strain and operation under cyclic pressures are considered.

  17. Stillage reflux in food waste ethanol fermentation and its by-product accumulation. (United States)

    Ma, Hongzhi; Yang, Jian; Jia, Yan; Wang, Qunhui; Tashiro, Yukihiro; Sonomoto, Kenji


    Raw materials and pollution control are key issues for the ethanol fermentation industry. To address these concerns, food waste was selected as fermentation substrate, and stillage reflux was carried out in this study. Reflux was used seven times during fermentation. Corresponding ethanol and reducing sugar were detected. Accumulation of by-products, such as organic acid, sodium chloride, and glycerol, was investigated. Lactic acid was observed to accumulate up to 120g/L, and sodium chloride reached 0.14mol/L. Other by-products did not accumulate. The first five cycles of reflux increased ethanol concentration, which prolonged fermentation time. Further increases in reflux time negatively influenced ethanol fermentation. Single-factor analysis with lactic acid and sodium chloride demonstrated that both factors affected ethanol fermentation, but lactic acid induced more effects.

  18. Effects of fermentation substrate conditions on corn-soy co-fermentation for fuel ethanol production. (United States)

    Yao, Linxing; Lee, Show-Ling; Wang, Tong; de Moura, Juliana M L N; Johnson, Lawrence A


    Soy skim, a protein-rich liquid co-product from the aqueous extraction of soybeans, was co-fermented with corn to produce ethanol. Effects of soy skim addition level, type of skim, corn particle size, water-to-solids ratio, and urea on co-fermentation were determined. The addition of 20-100% skim increased the fermentation rate by 18-27% and shortened the fermentation time by 5-7h without affecting ethanol yield. Finely ground corn or high water-to-solids ratio (≥ 3.0) in the mash gave higher fermentation rates, but did not increase the ethanol yield. When the water was completely replaced with soy skim, the addition of urea became unnecessary. Soy skim retentate that was concentrated by nanofiltration increased fermentation rate by 25%. The highest level of skim addition resulted in a finished beer with 16% solids, 47% protein (dwb) containing 3.6% lysine, and an ethanol yield of 39 g/100g dry corn.

  19. Intracellular ethanol accumulation in Saccharomyces cerevisiae during fermentation.


    D'Amore, T; C.J. Panchal; Stewart, G G


    An intracellular accumulation of ethanol in Saccharomyces cerevisiae was observed during the early stages of fermentation (3 h). However, after 12 h of fermentation, the intracellular and extracellular ethanol concentrations were similar. Increasing the osmotic pressure of the medium caused an increase in the ratio of intracellular to extracellular ethanol concentrations at 3 h of fermentation. As in the previous case, the intracellular and extracellular ethanol concentrations were similar af...

  20. Ethanol fermentation by immobilized cells of Zymomonas mobilis

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    Grote, W.


    Previous studies have shown that immobilized yeast cell cultures have commercial potential for fuel ethanol production. In this study the suitability of strains of Z. mobilis for whole cell immobilization was investigated. Experiments revealed that immobilization in Ca-alginate or K-carrageenan gel or use of flocculating strains was effective for ethanol production at relatively high productivities. Two laboratory size reactors were designed and constructed. These were a compartmented multiple discshaft column and a tower fermentor. Results of this work supported other studies that established that growth and fermentation could be uncoupled. The data indicated that specific metabolic rates were dependent on the nature of the fermentation media. The addition of lactobacilli to Z. mobilis continuous fermentations had only a transient effect, and was unlikely to affect an immobilized Z. mobilis process. With 150 gl/sup -1/ glucose media and a Z. mobilis ZM4 immobilized cell reactor, a maximum volumetric ethanol productivity of 55 gl/sup -1/h/sup -1/ was obtained. The fermentation of sucrose media or sucrose-based raw materials (molasses, cane juice, synthetic mill liquor) by immobilized Z. mobilis ZM4 revealed a pattern of rapid sucrose hydrolysis, preferential glucose utilization and the conversion of fructose to the undesirable by-products levan and sorbitol.

  1. Vacuum stripping of ethanol during high solids fermentation of corn. (United States)

    Shihadeh, Jameel K; Huang, Haibo; Rausch, Kent D; Tumbleson, Mike E; Singh, Vijay


    In corn-ethanol industry, yeast stress inducing glucose concentrations produced during liquefaction and subsequent high ethanol concentrations produced during fermentation restrict slurry solids to 32 % w/w. These limits were circumvented by combining two novel technologies: (1) granular starch hydrolyzing enzyme (GSHE) to break down starch simultaneously with fermentation and (2) vacuum stripping to remove ethanol. A vacuum stripping system was constructed and applied to fermentations at 30, 40, and 45 % solids. As solids increased from 30 to 40 %, ethanol yield decreased from 0.35 to 0.29 L/kg. Ethanol yield from 45 % solids was only 0.18 L/kg. An improvement was conducted by increasing enzyme dose from 0.25 to 0.75 g/g corn and reducing yeast inoculum by half. After improvement, ethanol yield from 40 % solids vacuum treatment increased to 0.36 L/kg, comparable to ethanol yield from 30 % solids (control).

  2. Fermentation to ethanol of pentose-containing spent sulphite liquor

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    Yu, S.; Wayman, M.; Parekh, S.K.


    Ethanolic fermentation of spent sulphite liquor with ordinary bakers' yeast is incomplete because this yeast cannot ferment the pentose sugars in the liquor. This results in poor alcohol yields, and a residual effluent problem. By using the yeast Candida shehatae (R) for fermentation of the spent sulphite liquor from a large Canadian alcohol-producing sulphite pulp and paper mill, pentoses as well as hexoses were fermented nearly completely, alcohol yields were raised by 33%, and sugar removal increased by 46%. Inhibitors were removed prior to fermentation by steam stripping. Major benefits were obtained by careful recycling of this yeast, which was shown to be tolerant both of high sugar concentrations and high alcohol concentrations. When sugar concentrations over 250 g/L (glucose:xylose 70:30) were fermented, ethanol became an inhibitor when its concentration reached 90 g/L. However, when the ethanol was removed by low-temperature vacuum distillation, fermentation continued and resulted in a yield of 0.50 g ethanol/g sugar consumed. Further improvement was achieved by combining enzyme saccharification of sugar oligomers with fermentation. This yeast is able to ferment both hexoses and pentoses simultaneously, efficiently, and rapidly. Present indications are that it is well suited to industrial operations wherever hexoses and pentoses are both to be fermented to ethanol, for example, in wood hydrolysates. (Refs. 6).

  3. Ethanol Production by Fermentation of Various Sweet-Stalk Sorghum Juices Using Various Yeast Strains

    Directory of Open Access Journals (Sweden)

    Donny Widianto


    Full Text Available The ethanol production by fermentation of sweet-stalk sorghum juice is affected by the juice composition and the capability of the yeast strain to ferment it. Eight yeast strains were tested on their growth and ethanol fermentation abilities in sweet-stalk sorghum juices extracted from three cultivars of sweet sorghum. The best specific growth rate of the yeast strains grown aerobically in the yeast extract peptone dextrose (YEPD broth and the sweet-stalk sorghum juices of KCS105, FS501, and FS902 cultivars, were achieved by OUT7903, OUT7913, OUT7903, and OUT7027 yeast strains, respectively. However, the best specific CO2 evolution rate of the yeast strain during fermentation of the juices was achieved by OUT7027 yeast strains. The highest ethanol concentration, ethanol yield, and sugar conversion efficiency (SCE were obtained by strain OUT7921 when it was employed to ferment sweet-stem sorghum juice of FS902 cultivar. It was also observed that the juice extracted from sweet-stalk sorghum of FS902 cultivar is the most suitable medium for all yeast strains to achieve their best fermentation abilities. Thus, it is likely that the growth and ethanol production ability of a yeast strain in sweet-stalk sorghum juice depend on the physiological responses of the yeasts to nutrientcomposition of the sorghum juice and the sorghum cultivar from which the juice was extracted.Key words : Sweet-stalk sorghum juice, ethanol, fermentation, yeast

  4. Ethanol Production by Fermentation of Various Sweet-Stalk Sorghum Juices Using Various Yeast Strains


    Donny Widianto; Akbar Arofatullah; Triwibowo Yuwono; Irfan Dwidya Prijambada


    The ethanol production by fermentation of sweet-stalk sorghum juice is affected by the juice composition and the capability of the yeast strain to ferment it. Eight yeast strains were tested on their growth and ethanol fermentation abilities in sweet-stalk sorghum juices extracted from three cultivars of sweet sorghum. The best specific growth rate of the yeast strains grown aerobically in the yeast extract peptone dextrose (YEPD) broth and the sweet-stalk sorghum juices of KCS105, FS501, and...

  5. Characterization of cellobiose fermentations to ethanol by yeasts

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    Freer, S.N.; Detroy, R.W.


    Twenty-two different yeasts were screened for their ability to ferment both glucose and cellobiose. The fermentation characteristics of Candida lusitaniae (NRRL Y-5394) and C. wickerhamii (NRRL Y-2563) were selected for further study because their initial rate of ethanol production from cellobiose was faster than the other test cultures. C. lusitaniae produced 44 g/L ethanol from 90 g/L cellobiose after 5-7 days. When higher carbohydrate concentrations were employed, fermentation ceased when the ethanol concentration reached 45-60 g/L. C. lusitaniae exhibited barely detectable levels of BETA-glucosidase, even though the culture actively fermented cellobiose. C. wickerhamii produced ethanol from cellobiose at a rate equivalent to C. lusitaniae; however, once the ethanol concentration reached 20 g/L, fermentation ceased. Using p-nitrophenyl-BETA-D-glucopyranoside (pNPG) as substrate, BETA-glucosidase (3-5 U/mL) was detected when C. wickerhamii was grown anaerobically on glucose or cellobiose. About 35% of the BETA-glucosidase activity was excreted into the medium. The cell-associated activity was highest against pNPG and salicin. Approximately 100-fold less activity was detected with cellobiose as substrate. When employing these organisms in a simultaneous saccharification-fermentation of avicel, using Trichoderma reesei cellulase as the saccharifying agent, 10-30% more ethanol was produced by the two yeasts capable of fermenting cellobiose than by the control, Saccharomyces cerevisiae.

  6. Fermentation to ethanol of pentose-containing spent sulfite liquor

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    Yu, S.; Wayman, M.; Parekh, S.K.


    Ethanolic fermentation of spent sulfite liquor with ordinary bakers' yeast is incomplete because of this yeast cannot ferment the pentose sugars in the liquor. This results in poor alcohol yields, and a residual effluent problem. By using the yeast Candida shehatae (R) for fermentation of the spent sulfite liquor from a large Canadian alcohol-producing sulfite pulp and paper mill, pentoses as well as hexoses were fermented nearly completely, alcohol yields were raised by 33%, and sugar removal increased by 46%. Inhibitors were removed prior to fermentation by steam stripping. Major benefits were obtained by careful recycling of this yeast, which was shown to be tolerant both of high sugar concentrations and high alcohol concentrations. When sugar concentrations over 250 g/L (glucose:xylose 70:30) were fermented, ethanol became an inhibitor when its concentration reached over 90 g/L. However, when the ethanol was removed by low-temperature vacuum distillation, fermentation continued and resulted in a yield of 0.50 g ethanol/g sugar consumed. Further improvement was achieved by combining enzyme saccharification of sugar oligomers with fermentation. This yeast is able to ferment both hexoses and pentoses simultaneously, efficiently, and rapidly.

  7. Methods for increasing the production of ethanol from microbial fermentation (United States)

    Gaddy, James L.; Arora, Dinesh K.; Ko, Ching-Whan; Phillips, John Randall; Basu, Rahul; Wikstrom, Carl V.; Clausen, Edgar C.


    A stable continuous method for producing ethanol from the anaerobic bacterial fermentation of a gaseous substrate containing at least one reducing gas involves culturing a fermentation bioreactor anaerobic, acetogenic bacteria in a liquid nutrient medium; supplying the gaseous substrate to the bioreactor; and manipulating the bacteria in the bioreactor by reducing the redox potential, or increasing the NAD(P)H TO NAD(P) ratio, in the fermentation broth after the bacteria achieves a steady state and stable cell concentration in the bioreactor. The free acetic acid concentration in the bioreactor is maintained at less than 5 g/L free acid. This method allows ethanol to be produced in the fermentation broth in the bioreactor at a productivity greater than 10 g/L per day. Both ethanol and acetate are produced in a ratio of ethanol to acetate ranging from 1:1 to 20:1.

  8. Liquefaction, saccharification, and fermentation of ammoniated corn to ethanol. (United States)

    Taylor, Frank; Kim, Tae Hyun; Abbas, Charles A; Hicks, Kevin B


    Treatment of whole corn kernels with anhydrous ammonia gas has been proposed as a way to facilitate the separation of nonfermentable coproducts before fermentation of the starch to ethanol, but the fermentability of ammoniated corn has not been thoroughly investigated. Also, it is intended that the added ammonia nitrogen in ammonia treated corn (approximately 1 g per kg corn) may satisfy the yeast nutritional requirement for free amino nitrogen (FAN). In this study, procedures for ammoniation, liquefaction, saccharification, and fermentation at two scales (12-L and 50-mL) were used to determine the fermentation rate, final ethanol concentration, and ethanol yield from starch in ammoniated or nonammoniated corn. The maximum achievable ethanol concentration at 50 h fermentation time was lower with ammoniated corn than with nonammoniated corn. The extra nitrogen in ammoniated corn satisfied some of the yeast requirements for FAN, thereby reducing the requirement for corn steep liquor. Based upon these results, ammoniation of corn does not appear to have a positive impact on the fermentability of corn to ethanol. Ammoniation may still be cost effective, if the advantages in terms of improved separations outweigh the disadvantages in terms of decreased fermentability.

  9. Effects of lactic acid bacteria contamination on lignocellulosic ethanol fermentation (United States)

    Slower fermentation rates, mixed sugar compositions, and lower sugar concentrations may make lignocellulosic fermentations more susceptible to contamination by lactic acid bacteria (LAB), which is a common and costly problem to the corn-based fuel ethanol industry. To examine the effects of LAB con...

  10. Fermentation of corn starch to ethanol with genetically engineered yeast. (United States)

    Inlow, D; McRae, J; Ben-Bassat, A


    Expression of the glucoamylase gene from Aspergillus awamori by laboratory and distiller's strains of Saccharomyces cerevisiae allowed them to ferment soluble starch. Approximately 95% of the carbohydrates in the starch were utilized. Glycerol production was significantly decreased when soluble starch was used instead of glucose. Ethanol yield on soluble starch was higher than that on glucose. The rate of starch fermentation was directly related to the level of glucoamylase activity. Strains with higher levels of glucoamylase expression fermented starch faster. The decline in starch fermentation rates toward the end of the fermentation was associated with accumulation of disaccharides and limit dextrins, poor substrates for glucoamylase. The buildup of these products in continuous fermentations inhibited glucoamylase activity and complete utilization of the starch. Under these conditions maltose-fermenting strains had a significant advantage over nonfermenting strains. The synthesis and secretion of glucoamylase showed no deleterious effects on cell growth rates, fermetation rates, and fermentation products.

  11. Bacteriophage application restores ethanol fermentation characteristics disrupted by Lactobacillus fermentum (United States)

    Background: Contamination of corn mash by lactic acid bacteria (LAB) reduces ethanol yields and the overall efficiency of the ethanol fermentation process, and the industry relies heavily on antibiotics for contamination control. There is a need to develop alternative methods for the control of cont...

  12. Adapting to alcohol: Dwarf hamster (Phodopus campbelli) ethanol consumption, sensitivity, and hoard fermentation. (United States)

    Lupfer, Gwen; Murphy, Eric S; Merculieff, Zoe; Radcliffe, Kori; Duddleston, Khrystyne N


    Ethanol consumption and sensitivity in many species are influenced by the frequency with which ethanol is encountered in their niches. In Experiment 1, dwarf hamsters (Phodopus campbelli) with ad libitum access to food and water consumed high amounts of unsweetened alcohol solutions. Their consumption of 15%, but not 30%, ethanol was reduced when they were fed a high-fat diet; a high carbohydrate diet did not affect ethanol consumption. In Experiment 2, intraperitoneal injections of ethanol caused significant dose-related motor impairment. Much larger doses administered orally, however, had no effect. In Experiment 3, ryegrass seeds, a common food source for wild dwarf hamsters, supported ethanol fermentation. Results of these experiments suggest that dwarf hamsters may have adapted to consume foods in which ethanol production naturally occurs.

  13. Ethanol fermentation integrated with PDMS composite membrane: An effective process. (United States)

    Fu, Chaohui; Cai, Di; Hu, Song; Miao, Qi; Wang, Yong; Qin, Peiyong; Wang, Zheng; Tan, Tianwei


    The polydimethylsiloxane (PDMS) membrane, prepared in water phase, was investigated in separation ethanol from model ethanol/water mixture and fermentation-pervaporation integrated process. Results showed that the PDMS membrane could effectively separate ethanol from model solution. When integrated with batch ethanol fermentation, the ethanol productivity was enhanced compared with conventional process. Fed-batch and continuous ethanol fermentation with pervaporation were also performed and studied. 396.2-663.7g/m(2)h and 332.4-548.1g/m(2)h of total flux with separation factor of 8.6-11.7 and 8-11.6, were generated in the fed-batch and continuous fermentation with pervaporation scenario, respectively. At the same time, high titre ethanol production of ∼417.2g/L and ∼446.3g/L were also achieved on the permeate side of membrane in the two scenarios, respectively. The integrated process was environmental friendly and energy saving, and has a promising perspective in long-terms operation.

  14. Adding value to carbon dioxide from ethanol fermentations. (United States)

    Xu, Yixiang; Isom, Loren; Hanna, Milford A


    Carbon dioxide (CO(2)) from ethanol production facilities is increasing as more ethanol is produced for alternative transportation fuels. CO(2) produced from ethanol fermentation processes is of high purity and is nearly a saturated gas. Such highly-concentrated source of CO(2) is a potential candidate for capture and utilization by the CO(2) industry. Quantity, quality and capture of CO(2) from ethanol fermentations are discussed in this review. The established and emerging value-added opportunities and markets for CO(2) from ethanol plants also are reviewed. The majority of CO(2) applications are dedicated to serving carbonated beverage and food processing and preservation markets. Beyond traditional merchant markets, the potential for exploring some fresh and profitable markets are discussed including carbon sources in chemical industries for the following: enhanced oil recovery; production of chemicals, fuels, and polymers; and production of algae-based biofuels through CO(2) fixation by microalgae.

  15. Effects of the Ionic Liquid 1-Butyl-3-methylimidazolium Chloride on the Growth and Ethanol Fermentation of Saccharomyces cerevisiae AY92022


    Zhu, S.; Yu, P.; Tong, Y; Chen, R.; Lv, Y.; Zhang, R.; Lei,M.; Ji, J; Chen, Q; Y Wu


    Use of ionic liquids has provided a potential effective alternative in the conversion of carbohydrates in lignocellulosic materials into fermentable sugars for ethanol production. To evaluate how the remained ionic liquids in the fermentable sugars affect the subsequent ethanol fermentation process, the effects of ionic liquid 1- butyl-3-methylimidazolium chloride ([Bmim]Cl) in the medium at different concentrations from 10–3 to 1 g L–1 on the morphological structure, growth and ethanol ferme...

  16. Production of ethanol at high temperatures in the fermentation of Jerusalem artichoke juice and a simple medium by Kluyveromyces marxianus

    Energy Technology Data Exchange (ETDEWEB)

    Rosa, M.F.; Correia, I.S.; Novais, J.M.


    Temperatures as high as 36 degrees C and 40 degrees C did not negatively affect the ethanol productivity of Jerusalem artichoke (J.a.) juice batch fermentation and the final concentrations of ethanol were close to those produced at lower temperatures. At higher process temperatures (36-40 degrees C), ethanol toxicity in Kluyveromyces marxianus was less important during the fermentation of J.a. juice as compared with a simple medium. In simple medium, the heat-sticking of fermentation was observed and the percentage of unfermented sugars steeply increased from 28 degrees C up to 40 degrees C. (Refs. 13).

  17. A biochemically structured model for ethanol fermentation by Kluyveromyces marxianus: A batch fermentation and kinetic study

    DEFF Research Database (Denmark)

    Sansonetti, Sascha; Hobley, Timothy John; Calabrò, V.


    Anaerobic batch fermentations of ricotta cheese whey (i.e. containing lactose) were performed under different operating conditions. Ethanol concentrations of ca. 22gL−1 were found from whey containing ca. 44gL−1 lactose, which corresponded to up to 95% of the theoretical ethanol yield within 15h...... coefficients within a physically meaningful range thereby providing valuable and reliable insight into fermentation processes....

  18. Continuous ethanol fermentation by beer yeast

    Energy Technology Data Exchange (ETDEWEB)

    Kida, Kenji; Morimura, Shigeru; Shima, Noriyuki; Asano, Shinichi; Yamadaki, Motozumi; Miyazawa, Toshiki


    Cooked and uncooked continuous fermentation tests and a bench-scale continuous fermentation test were carried out using a flocculating yeast, beer yeast IFO-2018, and using molasses of various origin. Heat of fermentation was measured at the same time. High productivity was found in a non-cooking continuous fermentation, but lowering of a flocculating ability was a problem. A theoretical equation for calculating the heat of fermentation was introduced and its adaptability was examined. The continuous fermentation unit was a single tank type using a tower type fermentor. The fermentor had a capacity of 0.7 l actual volume, made of glass, and consisted of the two parts, a flowing part and a precipitation/separation part. The yeast used was Saccharomyces crevisiae IFO-2018 in comparison with such yeast as S. cerevisiae IFO-0224 and S. cervisiae EP-1. (7 figs,3 tabs,21 refs)

  19. Protease increases fermentation rate and ethanol yield in dry-grind ethanol production. (United States)

    Johnston, David B; McAloon, Andrew J


    The effects of acid protease and urea addition during the fermentation step were evaluated. The fermentations were also tested with and without the addition of urea to determine if protease altered the nitrogen requirements of the yeast. Results show that the addition of the protease had a statistically significant effect on the fermentation rate and yield. Fermentation rates and yields were improved with the addition of the protease over the corresponding controls without protease. Protease addition either with or with added urea resulted in a higher final ethanol yield than without the protease addition. Urea addition levels >1200 ppm of supplemental nitrogen inhibited ethanol production. The economic effects of the protease addition were evaluated by using process engineering and economic models developed at the Eastern Regional Research Center. The decrease in overall processing costs from protease addition was as high as $0.01/L (4 ¢/gal) of denatured ethanol produced.

  20. Transient Behavior of Ethanol Fermentation in Immobilized Cell Bioreactors*


    Tohru, KANNO; Yoshinori, FUJISHIGE; Hiroyuki, Ito; koichi, yamazaki; Masayoshi, KOBAYASHI


    The dynamic behavior of ethanol fermentation catalysed by an immobilized cell has been studied in batch and continuous stirred tank bioreactors, changing the operating conditions in a stepwise fashion. The rate of ethanol fermentation in the flow reactor reaches a new steady state within 60 min for the stepwise change in temperature or flow rate at 15〜30℃ and the residence time t_R=40 hr. The rate of fermentation obeys the Lineweaven-Burk plot and the Michaelis constant is calculated

  1. Ammonia disinfection of corn grains intended for ethanol fermentation

    Directory of Open Access Journals (Sweden)

    Magdalena Broda


    Full Text Available Background. Bacterial contamination is an ongoing problem for commercial bioethanol plants. It concerns factories using grain and also other raw materials for ethanol fermentation. Bacteria compete with precious yeasts for sugar substrates and micronutrients, secrete lactic and acetic acids, which are toxic for yeast and this competition leads to significant decrease of bioethanol productivity. For this study, bacterial contamination of corn grain was examined. Then the grain was treated by ammonia solution to reduce microbial pollution and after that the microbiological purity of grain was tested one more time. Disinfected and non-disinfected corn grains were ground and fermentation process was performed. Microbiological purity of this process and ethanol yield was checked out. Material and methods. The grain was disinfected by ammonia solution for two weeks. Then the grain was milled and used as a raw material for the ethanol fermentation. The fermentation process was carried out in 500-ml Erlenmeyer flasks. Samples were withdrawn for analysis at 0, 24, 48, 72 hrs. The number of total viable bacteria, lactic acid bacteria, acetic acid bacteria, anaerobic bacteria and the quantity of yeasts and moulds were signified by plate method. Results. Ammonia solution effectively reduces bacterial contamination of corn grain. Mash from grain disinfected by ammonia contains less undesirable microorganisms than mash from crude grain. Moreover, ethanol yield from disinfected grain is at the highest level. Conclusions. The ammonia solution proved to be a good disinfection agent for grain used as a raw material for bioethanol fermentation process.

  2. Effects of soya fatty acids on cassava ethanol fermentation. (United States)

    Xiao, Dongguang; Wu, Shuai; Zhu, Xudong; Chen, Yefu; Guo, Xuewu


    Ethanol tolerance is a key trait of microbes in bioethanol production. Previous studies have shown that soya flour contributed to the increase of ethanol tolerance of yeast cells. In this paper, the mechanism of this ethanol tolerance improvement was investigated in cassava ethanol fermentation supplemented with soya flour or defatted soya flour, respectively. Experiment results showed that ethanol tolerance of cells from soya flour supplemented medium increased by 4-6% (v/v) than the control with defatted soya flour. Microscopic observation found that soya flour can retain the cell shape while dramatic elongations of cells were observed with the defatted soya flour supplemented medium. Unsaturated fatty acids (UFAs) compositions of cell membrane were analyzed and the UFAs amounts increased significantly in all tested strains grown in soya flour supplemented medium. Growth study also showed that soya flour stimulated the cell growth rate by approximately tenfolds at 72-h fermentation. All these results suggested that soya fatty acids play an important role to protect yeast cells from ethanol stress during fermentation process.

  3. D-xylulose fermentation to ethanol by Saccharomyces cerevisiae

    Energy Technology Data Exchange (ETDEWEB)

    Chiang, L.C.; Gong, C.S.; Chen, L.F.; Tsao, G.T.


    Commercial bakers' yeast (Saccharomyces cerevisiae) was used to study the conversion of D-xylulose to ethanol in the presence of D-xylose. The rate of ethanol production increased with an increase in yeast cell density. The optimal temperature for D-xylulose fermentation was 35 degrees Celcius, and the optimal pH range was 4 to 6. The fermentation of D-xylulose by yeast resulted in the production of ethanol as the major product; small amounts of xylitol and glycerol were also produced. The production of xylitol was influenced by pH as well as temperature. High pH values and low temperatures enhanced xylitol production. The rate of D-xylulose fermentation decreased when the production of ethanol yielded concentrations of 4% or more. The slow conversion rate of D-xylulose to ethanol was increased by increasing the yeast cell density. The overall production of ethanol from D-xylulose by yeast cells under optimal conditions was 90% of the theoretical yield. (Refs. 21).

  4. Traits of selected Clostridium strains for syngas fermentation to ethanol. (United States)

    Martin, Michael E; Richter, Hanno; Saha, Surya; Angenent, Largus T


    Syngas fermentation is an anaerobic bioprocess that could become industrially relevant as a biorefinery platform for sustainable production of fuels and chemicals. An important prerequisite for commercialization is adequate performance of the biocatalyst (i.e., sufficiently high production rate, titer, selectivity, yield, and stability of the fermentation). Here, we compared the performance of three potential candidate Clostridium strains in syngas-to-ethanol conversion: Clostridium ljungdahlii PETC, C. ljungdahlii ERI-2, and Clostridium autoethanogenum JA1-1. Experiments were conducted in a two-stage, continuously fed syngas-fermentation system that had been optimized for stable ethanol production. The two C. ljungdahlii strains performed similar to each other but different from C. autoethanogenum. When the pH value was lowered from 5.5 to 4.5 to induce solventogenesis, the cell-specific carbon monoxide and hydrogen consumption (similar rate for all strains at pH 5.5), severely decreased in JA1-1, but hardly in PETC and ERI-2. Ethanol production in strains PETC and ERI-2 remained relatively stable while the rate of acetate production decreased, resulting in a high ethanol/acetate ratio, but lower overall productivities. With JA1-1, lowering the pH severely lowered rates of both ethanol and acetate production; and as a consequence, no pronounced shift to solventogenesis was observed. The highest overall ethanol production rate of 0.301 g · L(-1)  · h(-1) was achieved with PETC at pH 4.5 with a corresponding 19 g/L (1.9% w/v) ethanol concentration and a 5.5:1 ethanol/acetate molar ratio. A comparison of the genes relevant for ethanol metabolism revealed differences between C. ljungdahlii and C. autoethanogenum that, however, did not conclusively explain the different phenotypes.

  5. Arrowroot as a novel substrate for ethanol production by solid state simultaneous saccharification and fermentation

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Tian-xiang; Tang, Qing-li; Zhu, Zuo-hua [School of Chemical Engineering, Guizhou University, Guizhou, Guiyang 550003 (China); Wang, Feng [National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China)


    Ethanol production from Canna edulis Ker was successfully carried out by solid state simultaneous saccharification and fermentation. The enzymatic hydrolysis conditions of C. edulis were optimized by Plackett-Burman design. The effect of inert carrier (corncob and rice bran) on ethanol fermentation and the kinetics of solid state simultaneous saccharification and fermentation was investigated. It was found that C. edulis was an alternative substrate for ethanol production, 10.1% (v/v) of ethanol concentration can attained when 40 g corncob and 10 g rice bran per 100 g C. edulis powder were added for ethanol fermentation. No shortage of fermentable sugars was observed during solid state simultaneous saccharification and fermentation. There was no wastewater produced in the process of ethanol production from C. edulis with solid state simultaneous saccharification and fermentation and the ethanol yield of more than 0.28 tonne per one tonne feedstock was achieved. This is first report for ethanol production from C. edulis powder. (author)

  6. Microbial fuel cell treatment of ethanol fermentation process water (United States)

    Borole, Abhijeet P [Knoxville, TN


    The present invention relates to a method for removing inhibitor compounds from a cellulosic biomass-to-ethanol process which includes a pretreatment step of raw cellulosic biomass material and the production of fermentation process water after production and removal of ethanol from a fermentation step, the method comprising contacting said fermentation process water with an anode of a microbial fuel cell, said anode containing microbes thereon which oxidatively degrade one or more of said inhibitor compounds while producing electrical energy or hydrogen from said oxidative degradation, and wherein said anode is in electrical communication with a cathode, and a porous material (such as a porous or cation-permeable membrane) separates said anode and cathode.

  7. Simultaneous saccharification and fermentation of cassava waste for ethanol production

    Directory of Open Access Journals (Sweden)

    C. Pothiraj


    Full Text Available The efficiency of enzymatic and microbial saccharification of cassava waste for ethanol production was investigated and the effective parameters were optimized. The mixture of amylase and amyloglucosidase (AMG resulted in a significantly higher rate of saccharification (79.6% than the amylase alone (68.7%. Simultaneous saccharification and fermentation (SSF yielded 6.2 g L-1 ethanol representing 64.5% of the theoretical yield. Saccharification and fermentation using pure and co-cultures of fungal isolates including Rhizopus stolonifer, Aspergillus terreus, Saccharomyces diastaticus and Zymomonas mobilis revealed that the co-culture system involving S. diastaticus and Z. mobilis was highly suitable for the bio-conversion of cassava waste into ethanol, resulting in 20.4 g L-1 in 36 h (91.3% of the theoretical yield.

  8. Solid phase fermentation of Helianthus tuberosus for ethanol

    Energy Technology Data Exchange (ETDEWEB)

    Baerwald, G.; Hamad, S.H.


    The direct fermentation of pure inulin and hammer mill crushed Helianthus tuberosus tubers (topinambur, Jerusalem artichoke) was studied using two heat-tolerant yeasts, namely Kluyveromyces marxianus and Candida kefyr. A Saccharomyces cerevisiae was included in the study so as to compare the yields of these two yeasts with that of a commercial distiller's yeast. The inulin fermentation was carried out in an 18-L bioreactor using the fed-batch and the batch-fermentation methods. The final ethanol concentration was 6.1% (L/L) which represents 82% of the theoretical yield. Commercial scale experiments with hammer mill crushed tubers gave yields lower than those found in the laboratory: 69% of the theoretical yield for direct fermentation without enzyme addition, and about 91% when cellolytic enzymes were added.

  9. [Effect of phenolic ketones on ethanol fermentation and cellular lipid composition of Pichia stipitis]. (United States)

    Yang, Jinlong; Cheng, Yichao; Zhu, Yuanyuan; Zhu, Junjun; Chen, Tingting; Xu, Yong; Yong, Qiang; Yu, Shiyuan


    Lignin degradation products are toxic to microorganisms, which is one of the bottlenecks for fuel ethanol production. We studied the effects of phenolic ketones (4-hydroxyacetophenone, 4-hydroxy-3-methoxy-acetophenone and 4-hydroxy-3,5-dimethoxy-acetophenone) derived from lignin degradation on ethanol fermentation of xylose and cellular lipid composition of Pichia stipitis NLP31. Ethanol and the cellular fatty acid of yeast were analyzed by high performance liquid chromatography (HPLC) and gas chromatography/mass spectrometry (GC/MS). Results indicate that phenolic ketones negatively affected ethanol fermentation of yeast and the lower molecular weight phenolic ketone compound was more toxic. When the concentration of 4-hydroxyacetophenone was 1.5 g/L, at fermentation of 24 h, the xylose utilization ratio, ethanol yield and ethanol concentration decreased by 42.47%, 5.30% and 9.76 g/L, respectively, compared to the control. When phenolic ketones were in the medium, the ratio of unsaturated fatty acids to saturated fatty acids (UFA/SFA) of yeast cells was improved. When 1.5 g/L of three aforementioned phenolic ketones was added to the fermentation medium, the UFA/SFA ratio of yeast cells increased to 3.03, 3.06 and 3.61, respectively, compared to 2.58 of the control, which increased cell membrane fluidity and instability. Therefore, phenolic ketones can reduce the yeast growth, increase the UFA/SFA ratio of yeast and lower ethanol productivity. Effectively reduce or remove the content of lignin degradation products is the key to improve lignocellulose biorefinery.

  10. Review: Continuous hydrolysis and fermentation for cellulosic ethanol production. (United States)

    Brethauer, Simone; Wyman, Charles E


    Ethanol made biologically from a variety of cellulosic biomass sources such as agricultural and forestry residues, grasses, and fast growing wood is widely recognized as a unique sustainable liquid transportation fuel with powerful economic, environmental, and strategic attributes, but production costs must be competitive for these benefits to be realized. Continuous hydrolysis and fermentation processes offer important potential advantages in reducing costs, but little has been done on continuous processing of cellulosic biomass to ethanol. As shown in this review, some continuous fermentations are now employed for commercial ethanol production from cane sugar and corn to take advantage of higher volumetric productivity, reduced labor costs, and reduced vessel down time for cleaning and filling. On the other hand, these systems are more susceptible to microbial contamination and require more sophisticated operations. Despite the latter challenges, continuous processes could be even more important to reducing the costs of overcoming the recalcitrance of cellulosic biomass, the primary obstacle to low cost fuels, through improving the effectiveness of utilizing expensive enzymes. In addition, continuous processing could be very beneficial in adapting fermentative organisms to the wide range of inhibitors generated during biomass pretreatment or its acid catalyzed hydrolysis. If sugar generation rates can be increased, the high cell densities in a continuous system could enable higher productivities and yields than in batch fermentations.

  11. Cooling of Ethanol Fermentation Process Using Absorption Chillers

    Directory of Open Access Journals (Sweden)

    Sergio Colle


    Full Text Available

    Ethanol fermentation is an exothermic process, where the kinetics depends on temperature. This study proposes an alternative cooling system for use in ethanol fermentation using a single-eect water/lithium bromide absorption chiller, powered by waste heat from sugar and ethanol production processes, with a temperature range of 80 to 100 oC. The aim of this study is to model, simulate and analyze the behavior of an absorption refrigeration machine, according to the required cooling capacity of the fermentation system. A comparative analysis with and without the chiller is performed. The introduction of a chiller allowed a reduction in the temperature of the medium of around 1 oC and an increase of around 0.8 % in the fermentation efficiency. Under these conditions less cellular stress occurs and cellular viability is kept at higher levels. The results show that this reduction in temperature can increase the ethanol content of the wine. In the recovery of ethanol, a lower thermal load will be needed at the distillation, with a smaller amount of vinasse produced and consequently the energy efficiency of the plant will increase.

  12. Magnetically altered ethanol fermentation capacity of Saccharomyces cerevisiae

    Directory of Open Access Journals (Sweden)

    Galonja-Corghill Tamara


    Full Text Available We studied the effect of static magnetic fields on ethanol production by yeast Saccharomyces cerevisiae 424A (LNH-ST using sugar cane molasses during the fermentation in an enclosed bioreactor. Two static NdFeB magnets were attached to a cylindrical tube reactor with their opposite poles (north to south, creating 150 mT magnetic field inside the reactor. Comparable differences emerged between the results of these two experimental conditions. We found ethanol productivity to be 15% higher in the samples exposed to 150 mT magnetic field.

  13. Use of biomass energy. Saccharification of raw starch and ethanol fermentation

    Energy Technology Data Exchange (ETDEWEB)

    Ueda, S.


    Raw starch was saccharified under acidic condition of pH 3.5 using black-koji amylase, and the resultant saccharidies were fermented to give ethanol in succession. White polished rice flour was fermented at 30 degrees C during the period of 7 to 10 days to give ethanol. Semi-continuous ethanol fermentation was carried out using corn starch and cassava starch. Batch ethanol fermentation was also carried out using cassava or sweet potato. Sweet potato was fermented using Rhizopus gluco-amylase. 11 references.

  14. Enhancement of fermentative hydrogen/ethanol production from cellulose using mixed anaerobic cultures

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Chiu-Yue; Hung, Wen-Chin [BioHydrogen Laboratory, Department of Environmental Engineering and Science, Feng Chia University, Taichung 40724 (China)


    Batch tests were conducted to evaluate the enhancement of hydrogen/ethanol (EtOH) productivity using cow dung microflora to ferment {alpha}-cellulose and saccharification products (glucose and xylose). Hydrogen/ethanol production was evaluated based on hydrogen/ethanol yields (HY/EY) under 55 C at various initial pH conditions (5.5-9.0). Our test results indicate that cow dung sludge is a good mixed natural-microflora seed source for producing biohydrogen/ethanol from cellulose and xylose. The heat-pretreatment, commonly used to produce hydrogen more efficiently from hexose, applied to mixed anaerobic cultures did not help cow dung culture convert cellulose and xylose into hydrogen/ethanol. Instead of heat-pretreatment, the mixed culture received enrichments cultivated at 55 C for 4 days. Positive results were observed: hydrogen/ethanol production from fermenting cellulose and xylose was effectively enhanced at increases of 4.8 (ethanol) to 8 (hydrogen) and 2.4 (ethanol) to 15.6 (hydrogen) folds, respectively. In which, the ethanol concentration produced from xylose reached 4-4.4 g/L, an output comparable to that of using heat-treated sewage sludge and better than that (1.25-3 g/L) using pure cultures. Our test results show that for the enriched cultures the initial cultivation pH can affect hydrogen/ethanol production including HY, EY and liquid fermentation product concentration and distribution. These results were also concurred using a denaturing gradient gel electrophoresis analysis saying that both cultivation pH and substrate can affect the enriched cow dung culture microbial communities. The enriched cow dung culture had an optimal initial cultivation pH range of 7.6-8.0 with peak HY/EY values of 2.8 mmol-H{sub 2}/g-cellulose, 5.8 mmol-EtOH/g-cellulose, 0.3 mol-H{sub 2}/mol-xylose and 1 mol-EtOH/mol-xylose. However, a pH change of 0.5 units from the optimal values reduced hydrogen/ethanol production efficiency by 20%. Strategies based on the experimental

  15. High-temperature fermentation. How can processes for ethanol production at high temperatures become superior to the traditional process using mesophilic yeast?

    Energy Technology Data Exchange (ETDEWEB)

    Abdel-Banat, Babiker M.A.; Hoshida, Hisashi; Nonklang, Sanom; Akada, Rinji [Yamaguchi Univ. Graduate School of Medicine, Ube (Japan). Dept. of Applied Molecular Bioscience; Ano, Akihiko [Iwata Chemical Co. Ltd. (Japan)


    The process of ethanol fermentation has a long history in the production of alcoholic drinks, but much larger scale production of ethanol is now required to enable its use as a substituent of gasoline fuels at 3%, 10%, or 85% (referred to as E3, E10, and E85, respectively). Compared with fossil fuels, the production costs are a major issue for the production of fuel ethanol. There are a number of possible approaches to delivering cost-effective fuel ethanol production from different biomass sources, but we focus in our current report on high-temperature fermentation using a newly isolated thermotolerant strain of the yeast Kluyveromyces marxianus. We demonstrate that a 5 C increase only in the fermentation temperature can greatly affect the fuel ethanol production costs. We contend that this approach may also be applicable to the other microbial fermentations systems and propose that thermotolerant mesophilic microorganisms have considerable potential for the development of future fermentation technologies. (orig.)

  16. Ethanolic fermentation in whey and whey-molasses mixtures. Pt. 2. Two-stage fermentation process of ethanol production from whey and beet molasses

    Energy Technology Data Exchange (ETDEWEB)

    Zakrzewski, E.; Zmarlicki, S.


    A two-stage fermentation process has been developed for ethanol production from regular or partly concentrated whey and molasses. In the first stage ethanolic fermentation in whey is performed with Kluyveromyces marxianus subsp. marxianus. Such prefermented whey is then used for dilution of molasses instead of water and the resulting medium subjected to the second stage fermentation performed with Saccharomyces cerevisiae. The process enables complete fermentation of lactose and all fermentble sugars from molasses, leading to an ethanol content of about 10% in the final medium, which makes the distillation much more economical than the separate processing of whey and molasses into spirit.

  17. Direct fermentation of cellulose to ethanol by a cellulolytic filamentous fungus, monilia sp

    Energy Technology Data Exchange (ETDEWEB)

    Gong, C.S.; Maun, C.M.; Tsao, G.T.


    Monilia, isolated from bagasse compost, utilized many polysaccharides (including cellulose) and displayed cellulase and hemicellulase activities. Monilia also fermented glucose, xylose, and cellulosic materials to ethanol. Over 60% of the solid cellulose substrate added to Monilia cultures was converted to ethanol as the major fermentation product. Thus, Monilia is a potential organism for the direct conversion of cellulosic biomass to ethanol.

  18. Study of simultaneous saccharification and fermentation for steam exploded wheat straw to ethanol

    Institute of Scientific and Technical Information of China (English)

    Peng LUO; Zhong LIU; Chuanmin YANG; Gaosheng WANG


    Although simultaneous saccharification and fermentation (SSF) has been investigated extensively, the optimum condition for SSF of wheat straw has not yet been determined. Dilute sulfuric acid impregnated and steam explosion pretreated wheat straw was used as a substrate for the production of ethanol by SSF through orthogonal experiment design in this study. Cellulase mix-ture (Celluclast 1.5 1 and β-glucosidase Novozym 188) were adopted in combination with the yeast Sacchar-omyces cerevisiae AS2.1. The effects of reaction temper-ature, substrate concentration, initial fermentation liquid pH value and enzyme loading were evaluated and the SSF conditions were optimized. The ranking, from high to low, of influential extent of the SSF affecting factors to ethanol concentration and yield was substrate concentra-tion, enzyme loading, initial fermentation liquid pH value and reaction temperature, respectively. The optimal SSF conditions were: reaction temperature, 35℃; substrate the ethanol concentration increased with reaction time, and after 72 h, ethanol was obtained in 65.8% yield with

  19. Cellulosic fuel ethanol: alternative fermentation process designs with wild-type and recombinant Zymomonas mobilis. (United States)

    Lawford, Hugh G; Rousseau, Joyce D


    Iogen (Canada) is a major manufacturer of industrial cellulase and hemicellulase enzymes for the textile, pulp and paper, and poultry feed industries. Iogen has recently constructed a 40 t/d biomass-to-ethanol demonstration plant adjacent to its enzyme production facility. The integration of enzyme and ethanol plants results in significant reduction in production costs and offers an alternative use for the sugars generated during biomass conversion. Iogen has partnered with the University of Toronto to test the fermentation performance characteristics of metabolically engineered Zymomonas mobilis created at the National Renewable Energy Laboratory. This study focused on strain AX101, a xylose- and arabinose-fermenting stable genomic integrant that lacks the selection marker gene for antibiotic resistance. The "Iogen Process" for biomass depolymerization consists of a dilute-sulpfuric acid-catalyzed steam explosion, followed by enzymatic hydrolysis. This work examined two process design options for fermentation, first, continuous cofermentation of C5 and C6 sugars by Zm AX101, and second, separate continuous fermentations of prehydrolysate by Zm AX101 and cellulose hydrolysate by either wildtype Z. mobilis ZM4 or an industrial yeast commonly used in the production of fuel ethanol from corn. Iogen uses a proprietary process for conditioning the prehydrolysate to reduce the level of inhibitory acetic acid to at least 2.5 g/L. The pH was controlled at 5.5 and 5.0 for Zymomonas and yeast fermentations, respectively. Neither 2.5 g/L of acetic acid nor the presence of pentose sugars (C6:C5 = 2:1) appreciably affected the high-performance glucose fermentation of wild-type Z. mobilis ZM4. By contrast, 2.5 g/L of acetic acid significantly reduced the rate of pentose fermentation by strain AX101. For single-stage continuous fermentation of pure sugar synthetic cellulose hydrolysate (60 g/L of glucose), wild-type Zymomonas exhibited a four-fold higher volumetric productivity

  20. Ethanol-induced leakage in Saccharomyces cerevisiae: kinetics and relationship to yeast ethanol tolerance and alcohol fermentation productivity

    Energy Technology Data Exchange (ETDEWEB)

    Salgueiro, S.P.; Sa-Correia, I.; Novais, J.M.


    Ethanol stimulated the leakage of amino acids and 260-nm-light-absorbing compounds from cells of Saccharomyces cerevisiae. The efflux followed first-order kinetics over an initial period. In the presence of lethal concentrations of ethanol, the efflux rates at 30 and 36/sup 0/C were an exponential function of ethanol concentration. At 36/sup 0/C, as compared with the corresponding values at 30/sup 0/C, the efflux rates were higher and the minimal concentration of ethanol was lower. The exponential constants for the enhancement of the rate of leakage had similar values at 30 or 36/sup 0/C and were of the same order of magnitude as the corresponding exponential constants for ethanol-induced death. Under isothermic conditions (30/sup 0/C) and up to 22% (vol/vol) ethanol, the resistance to ethanol-induced leakage of 260-nm-light-absorbing compounds was found to be closely related with the ethanol tolerance of three strains of yeasts, Kluyveromyces marxianus, Saccharomyces cerevisiae, and Saccharomyces bayanus. The resistance to ethanol-induced leakage indicates the possible adoption of the present method for the rapid screening of ethanol-tolerant strains. The addition to a fermentation medium of the intracellular material obtained by ethanol permeabilization of yeast cells led to improvements in alcohol fermentation by S. cerevisiae and S. bayanus. The action of the intracellular material, by improving yeast ethanol tolerance, and the advantages of partially recycling the fermented medium after distillation were discussed.

  1. 'Killer' character of yeasts isolated from ethanolic fermentations

    Directory of Open Access Journals (Sweden)

    Ceccato-Antonini Sandra Regina


    Full Text Available The number of killer, neutral and sensitive yeasts was determined from strains isolated from substrates related to alcoholic fermentations. From 113 isolates, 24 showed killer activity against NCYC 1006 (standard sensitive strain, while 30 were sensitive to NCYC 738 (standard killer strain, and 59 had no reaction in assays at 25-27°C. Two wild yeast strains of Saccharomyces cerevisiae and one of Candida colliculosa were tested against 10 standard killer strains and one standard sensitive strain in a cell x cell and well-test assays at four different pHs. None of the isolates displayed strong killer activity or were sensitive to the standard strains. All belonged to the neutral type. It was concluded that although the number of killer strains was high, this character cannot be used to protect ethanol fermentation processes against yeast contaminants like those which form cell clusters.

  2. Batch and Fed-Batch Fermentation System on Ethanol Production from Whey using Kluyveromyces marxianus

    Directory of Open Access Journals (Sweden)

    H Hadiyanto


    Full Text Available Nowadays reserve of fossil fuel has gradually depleted. This condition forces many researchers to  find energy alternatives which is renewable and sustainable in the future. Ethanol derived from cheese industrial waste (whey using fermentation process can be a new perspective in order to secure both energy and environment. The aim of this study was  to compare the operation modes (batch and fed-batch of fermentation system on ethanol production from whey using Kluyveromyces marxianus. The result showed that the fermentation process for ethanol production by fed-batch system was higher at some point of parameters compared with batch system. Growth rate and ethanol yield (YP/S of fed-batch fermentation were 0.122/h and 0.21 gP/gS respectively; growth rate and ethanol yield (YP/S of batch fermentation were 0.107/h, and 0.12 g ethanol/g substrate, respectively. Based on the data of biomass and ethanol concentrations, the fermentation process for ethanol production by fed-batch system were higher at some point of parameters compared to batch system. Periodic substrate addition performed on fed-batch system leads the yeast growth in low substrate concentrations and consequently  increasing their activity and ethanol productivity. Keywords: batch; ethanol; fed-batch; fermentation;Kluyveromyces marxianus, whey

  3. 发酵抑制物对葡萄糖发酵产乙醇的影响%Effects of fermentation inhibitors on ethanol production of glucose fermentation

    Institute of Scientific and Technical Information of China (English)

    李志强; 费本华; 江泽慧


    在纤维素乙醇研究中,木质纤维原料在酸性预处理过程中会产生甲酸、乙酸、乙酰丙酸、糠醛和5-羟甲基糠醛等发酵抑制物,这些发酵抑制物会影响葡萄糖发酵生产乙醇的收率。本文考察了发酵液中各种发酵抑制物含量对高温超级酿酒酵母发酵乙醇收率的影响。研究结果表明,多种发酵抑制物的协同作用对乙醇发酵的影响要高于单一种类发酵抑制物对乙醇发酵的影响。发酵液中发酵抑制物总量一般控制在3.0g/L以内时,对葡萄糖发酵生产乙醇的抑制作用不明显。%In pretreatments of lignocellulosic materials for bioethanol production,certain amount of sugars was degraded as fermentation inhibitors,and the degradation was much more severe in the acidic pretreatment.Theses fermentations inhibitors including formic acid, acetic acid, levulinic acid,furfural,and 5-hydroxymethylfurfural (HMF)which affect the conversion yield of ethanol from glucose fermentation.This paper examined the effect of the five fermentation inhibitors concentration on the ethanol yield of Saccharomyces cerevisiae glucose fermentation. The results show that, synergistic effect of various fermentation inhibitors on ethanol fermentation was higher than single fermentation inhibitor on ethanol fermentation.The total fermentation inhibitors in fermentation solutions generally controlled within 3.0g/L,which inhibitory effect on glucose fermentation for ethanol is not obvious.

  4. Efficient production of ethanol from waste paper and the biochemical methane potential of stillage eluted from ethanol fermentation. (United States)

    Nishimura, Hiroto; Tan, Li; Sun, Zhao-Yong; Tang, Yue-Qin; Kida, Kenji; Morimura, Shigeru


    Waste paper can serve as a feedstock for ethanol production due to being rich in cellulose and not requiring energy-intensive thermophysical pretreatment. In this study, an efficient process was developed to convert waste paper to ethanol. To accelerate enzymatic saccharification, pH of waste paper slurry was adjusted to 4.5-5.0 with H2SO4. Presaccharification and simultaneous saccharification and fermentation (PSSF) with enzyme loading of 40 FPU/g waste paper achieved an ethanol yield of 91.8% and productivity of 0.53g/(Lh) with an ethanol concentration of 32g/L. Fed-batch PSSF was used to decrease enzyme loading to 13 FPU/g waste paper by feeding two separate batches of waste paper slurry. Feeding with 20% w/w waste paper slurry increased ethanol concentration to 41.8g/L while ethanol yield decreased to 83.8%. To improve the ethanol yield, presaccharification was done prior to feeding and resulted in a higher ethanol concentration of 45.3g/L, a yield of 90.8%, and productivity of 0.54g/(Lh). Ethanol fermentation recovered 33.2% of the energy in waste paper as ethanol. The biochemical methane potential of the stillage eluted from ethanol fermentation was 270.5mL/g VTS and 73.0% of the energy in the stillage was recovered as methane. Integrating ethanol fermentation with methane fermentation, recovered a total of 80.4% of the energy in waste paper as ethanol and methane.

  5. La fermentation éthanolique. Les microorganismes Ethanol Fermentation. The Microorganisms

    Directory of Open Access Journals (Sweden)

    Ballerini D.


    Full Text Available Cette étude précise l'état actuel des connaissances concernant la fermentation éthanolique, d'un point de vue microbiologique. Outre les microorganismes utilisés depuis longtemps, sont décrites les nouvelles espèces de levures et de bactéries capables de transformer en éthanol des substrats aussi divers que les composés cellulosiques et hémicellulosiques issus de la biomasse et leurs produits d'hydrolyse. Pour la fermentation des substrats traditionnels tels que les mélasses et les jus d'extraction de plantes sucrières, ou encore l'amidon de maïs, les performances des levures du genre Saccharomyces sont comparées à celles des bactéries du genre Zymomonas. This review gives the state-of-the-art of what is known about ethanol fermentation from the microbiological viewpoint. In addition to the microorganisms that have been used for a long time, it describes new species of yeasts and bacteria capable of transforming, in ethanol, substrates including such different ones as cellulosic and hemicellulosic compounds issuing from biomass and their hydrolysis products. For the fermentation of traditional substrates such as molasses and juices extracted from sugar plants, or cornstarch, the performances of yeasts of the Saccharomyces type are compared to those of bacteria of the Zymomonas type.

  6. Effect of manganese ions on ethanol fermentation by xylose isomerase expressing Saccharomyces cerevisiae under acetic acid stress. (United States)

    Ko, Ja Kyong; Um, Youngsoon; Lee, Sun-Mi


    The efficient fermentation of lignocellulosic hydrolysates in the presence of inhibitors is highly desirable for bioethanol production. Among the inhibitors, acetic acid released during the pretreatment of lignocellulose negatively affects the fermentation performance of biofuel producing organisms. In this study, we evaluated the inhibitory effects of acetic acid on glucose and xylose fermentation by a high performance engineered strain of xylose utilizing Saccharomyces cerevisiae, SXA-R2P-E, harboring a xylose isomerase based pathway. The presence of acetic acid severely decreased the xylose fermentation performance of this strain. However, the acetic acid stress was alleviated by metal ion supplementation resulting in a 52% increased ethanol production rate under 2g/L of acetic acid stress. This study shows the inhibitory effect of acetic acid on an engineered isomerase-based xylose utilizing strain and suggests a simple but effective method to improve the co-fermentation performance under acetic acid stress for efficient bioethanol production.

  7. Ethanol at levels produced by Saccharomyces cerevisiae during wheat dough fermentation has a strong impact on dough properties. (United States)

    Jayaram, Vinay B; Rezaei, Mohammad N; Cuyvers, Sven; Verstrepen, Kevin J; Delcour, Jan A; Courtin, Christophe M


    Yeast's role in bread making is primarily the fermentative production of carbon dioxide to leaven the dough. Fermentation also impacts dough matrix rheology, thereby affecting the quality of the end product. Surprisingly, the role of ethanol, the other yeast primary metabolite, has been ill studied in this context. Therefore, this study aims to assess the potential impact of ethanol on yeastless dough extensibility and spread and gluten agglomeration at concentrations at which it is produced in fermenting dough, i.e., up to 60 mmol per 100 g of flour. Reduced dough extensibility and dough spread were observed upon incorporation of ethanol in the dough formula, and were more pronounced for a weak than for a strong flour. Uniaxial and biaxial extension tests showed up to 50% decrease in dough extensibility and a dough strength increase of up to 18% for 60 mmol of ethanol/100 g of flour. Ethanol enhanced gluten agglomeration of a weak flour. Sequential extraction of flour in increasing ethanol concentrations showed that better gluten-solvent interaction is a possible explanation for the changed dough behavior.

  8. Shuidouchi (Fermented Soybean) Fermented in Different Vessels Attenuates HCl/Ethanol-Induced Gastric Mucosal Injury. (United States)

    Suo, Huayi; Feng, Xia; Zhu, Kai; Wang, Cun; Zhao, Xin; Kan, Jianquan


    Shuidouchi (Natto) is a fermented soy product showing in vivo gastric injury preventive effects. The treatment effects of Shuidouchi fermented in different vessels on HCl/ethanol-induced gastric mucosal injury mice through their antioxidant effect was determined. Shuidouchi contained isoflavones (daidzein and genistein), and GVFS (glass vessel fermented Shuidouchi) had the highest isoflavone levels among Shuidouchi samples fermented in different vessels. After treatment with GVFS, the gastric mucosal injury was reduced as compared to the control mice. The gastric secretion volume (0.47 mL) and pH of gastric juice (3.1) of GVFS treated gastric mucosal injury mice were close to those of ranitidine-treated mice and normal mice. Shuidouchi could decrease serum motilin (MTL), gastrin (Gas) level and increase somatostatin (SS), vasoactive intestinal peptide (VIP) level, and GVFS showed the strongest effects. GVFS showed lower IL-6, IL-12, TNF-α and IFN-γ cytokine levels than other vessel fermented Shuidouchi samples, and these levels were higher than those of ranitidine-treated mice and normal mice. GVFS also had higher superoxide dismutase (SOD), nitric oxide (NO) and malonaldehyde (MDA) contents in gastric tissues than other Shuidouchi samples. Shuidouchi could raise IκB-α, EGF, EGFR, nNOS, eNOS, Mn-SOD, Gu/Zn-SOD, CAT mRNA expressions and reduce NF-κB, COX-2, iNOS expressions as compared to the control mice. GVFS showed the best treatment effects for gastric mucosal injuries, suggesting that glass vessels could be used for Shuidouchi fermentation in functional food manufacturing.

  9. Continuous high-solids corn liquefaction and fermentation with stripping of ethanol. (United States)

    Taylor, Frank; Marquez, Marco A; Johnston, David B; Goldberg, Neil M; Hicks, Kevin B


    Removal of ethanol from the fermentor during fermentation can increase productivity and reduce the costs for dewatering the product and coproduct. One approach is to recycle the fermentor contents through a stripping column, where a non-condensable gas removes ethanol to a condenser. Previous research showed that this approach is feasible. Savings of $0.03 per gallon were predicted at 34% corn dry solids. Greater savings were predicted at higher concentration. Now the feasibility has been demonstrated at over 40% corn dry solids, using a continuous corn liquefaction system. A pilot plant, that continuously fed corn meal at more than one bushel (25 kg) per day, was operated for 60 consecutive days, continuously converting 95% of starch and producing 88% of the maximum theoretical yield of ethanol. A computer simulation was used to analyze the results. The fermentation and stripping systems were not significantly affected when the CO(2) stripping gas was partially replaced by nitrogen or air, potentially lowering costs associated with the gas recycle loop. It was concluded that previous estimates of potential cost savings are still valid.

  10. High gravity fermentation of sugarcane molasses to produce ethanol: Effect of nutrients


    Pradeep, P; Reddy, O. V. S.


    Fermentation efficiency of more than 85% was obtained by high gravity fermentation of 33–34°Bx (spec. gravity ≈1.134) molasses medium with certain nutrients, instead of generally employed medium containing ≈16% (w/v) total sugar (spec. gravity ≈1.090) for ethanol fermentation in distilleries to get maximum 80–85% conversion. The fermenting yeast, Saccharomyces, has varied capabilities, depending on the species and nutrition for fermenting the high solids medium. The fermentation period was re...

  11. Enhanced ethanol fermentation of brewery wastewater using the genetically modified strain E. coli KO11. (United States)

    Rao, Kripa; Chaudhari, Vaibhav; Varanasi, Sasidhar; Kim, Dong-Shik


    We have used liquid waste obtained from a beer brewery process to produce ethanol. To increase the productivity, genetically modified organism, Escherichia coli KO11, was used for ethanol fermentation. Yeast was also used to produce ethanol from the same feed stock, and the ethanol production rates and resulting concentrations of sugars and ethanol were compared with those of KO11. In the experiments, first the raw wastewater was directly fermented using two strains with no saccharification enzymes added. Then, commercial enzymes, alpha-amylase, pectinase, or a combination of both, were used for simultaneous saccharification and fermentation, and the results were compared with those of the no-enzyme experiments for KO11 and yeast. Under the given conditions with or without the enzymes, yeast produced ethanol more rapidly than E. coli KO11, but the final ethanol concentrations were almost the same. For both yeast and KO11, the enzymes were observed to enhance the ethanol yields by 61-84% as compared to the fermentation without enzymes. The combination of the two enzymes increased ethanol production the most for the both strains. The advantages of using KO11 were not demonstrated clearly as compared to the yeast fermentation results.

  12. Effect of soy skim from soybean aqueous processing on the performance of corn ethanol fermentation. (United States)

    Yao, Linxing; Wang, Tong; Wang, Hui


    The feasibility of using soy skim, a co-product of the aqueous processing of soybeans, in ethanol production from corn was evaluated. Specific growth rates were compared when Saccharomyces cerevisiae was grown in soy skim and peptone-yeast extract media supplemented with glucose. Such soy skim was proved to be a good nitrogen source for yeast growth. Next, fermentation of dry-ground corn to ethanol using soy skim as the media was simulated on 1.5-L scale. Replacing water with soy skim increased the initial ethanol production rates by 4-32% while final ethanol yield was about 39 g/100 g dry corn, similar to the result when water was used. Solid and protein contents in the finished beer increased with the addition of soy skim. Thus, replacing water in corn-ethanol fermentation with soy skim is feasible, and may improve the economics of both aqueous soybean processing and corn ethanol fermentation.

  13. Characterization of cellobiose fermentations to ethanol by yeasts. [Candida lusitaniae and C. wickerhamii

    Energy Technology Data Exchange (ETDEWEB)

    Freer, S.N.; Detroy, R.W.


    Twenty-two different yeasts were screened for their ability to ferment both glucose and cellobiose. The fermentation characteristics of Candida lusitaniae (NRRL Y-5394) and C. wickerhamii (NRRL Y-2563) were selected for further study because their initial rate of ethanol production from cellobiose was faster than the other test culture. C. lusitaniae produced 44 g/L ethanol from 90 g/L cellobiose after 5-7 days. When carbohydrate concentrations were employed, fermentation ceased when the ethanol concentration reached 45-60 g/L. C. lusitaniae exhibited barely detectable levels of beta-glucosidase, even though the culture actively fermented cellobiose. C. wickerhamii produced ethanol from cellobiose at a rate equivalent to C. lusitaniae; however, once the ethanol concentration reached 20 g/L, fermentation ceased. Using p-nitrophenyl-beta-D-glucopyranoside (pNPG) as substrate, beta- glucosidase (3-5 U/mL) was detected when C. wickerhamii was grown anaerobically on glucose or cellobiose. About 35% of the beta-glucosidase activity was excreted into the medium. The cell-associated activity was highest against pNPG and salicin. Approximately 100-fold less activity was detected with cellobiose as substrate. When employing these organisms in a simultaneous saccharification-fermentation of Avicel, using Trichoderma reesei cellulase as the saccharifying agent 10-30% more ethanol was produced by the two yeasts capable of fermenting cellobiose than by the control, Saccharomyces cerevisiae. (Refs. 27).

  14. Fermentation of biologically pretreated wheat straw for ethanol production: comparison of fermentative microorganisms and process configurations. (United States)

    López-Abelairas, María; Lu-Chau, Thelmo Alejandro; Lema, Juan Manuel


    The pretreatment of lignocellulosic biomass with white-rot fungi to produce bioethanol is an environmentally friendly alternative to the commonly used physico-chemical processes. After biological pretreatment, a solid substrate composed of cellulose, hemicellulose and lignin, the two latter with a composition lower than that of the initial substrate, is obtained. In this study, six microorganisms and four process configurations were utilised to ferment a hydrolysate obtained from wheat straw pretreated with the white-rot fungus Irpex lacteus. To enhance total sugars utilisation, five of these microorganisms are able to metabolise, in addition to glucose, most of the pentoses obtained after the hydrolysis of wheat straw by the application of a mixture of hemicellulolytic and cellulolytic enzymes. The highest overall ethanol yield was obtained with the yeast Pachysolen tannophilus. Its application in combination with the best process configuration yielded 163 mg ethanol per gram of raw wheat straw, which was between 23 and 35 % greater than the yields typically obtained with a conventional bioethanol process, in which wheat straw is pretreated using steam explosion and fermented with the yeast Saccharomyces cerevisiae.

  15. Inhibitory effect of ethanol, acetic acid, propionic acid and butyric acid on fermentative hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Bo; Wan, Wei; Wang, Jianlong [Laboratory of Environmental Technology, INET, Tsinghua University, Beijing 100084 (China)


    The inhibitory effect of added ethanol, acetic acid, propionic acid and butyric acid on fermentative hydrogen production by mixed cultures was investigated in batch tests using glucose as substrate. The experimental results showed that, at 35 C and initial pH 7.0, during the fermentative hydrogen production, the substrate degradation efficiency, hydrogen production potential, hydrogen yield and hydrogen production rate all trended to decrease with increasing added ethanol, acetic acid, propionic acid and butyric acid concentration from 0 to 300 mmol/L. The inhibitory effect of added ethanol on fermentative hydrogen production was smaller than those of added acetic acid, propionic acid and butyric acid. The modified Han-Levenspiel model could describe the inhibitory effects of added ethanol, acetic acid, propionic acid and butyric acid on fermentative hydrogen production rate in this study successfully. The modified Logistic model could describe the progress of cumulative hydrogen production. (author)

  16. Removal of the Fermentation Inhibitor, Furfural, Using Activated Carbon in Cellulosic-Ethanol Production

    KAUST Repository

    Zhang, Kuang


    Ethanol can be produced from lignocellulosic biomass through fermentation; however, some byproducts from lignocellulosics, such as furfural compounds, are highly inhibitory to the fermentation and can substantially reduce the efficiency of ethanol production. In this study, commercial and polymer-derived activated carbons were utilized to selectively remove the model fermentation inhibitor, furfural, from water solution during bioethanol production. The oxygen functional groups on the carbon surface were found to influence the selectivity of sorbents between inhibitors and sugars during the separation. After inhibitors were selectively removed from the broth, the cell growth and ethanol production efficiency was recovered noticeably in the fermentation. A sorption/desorption cycle was designed, and the sorbents were regenerated in a fixed-bed column system using ethanol-containing standard solution. Dynamic mass balance was obtained after running four or five cycles, and regeneration results were stable even after twenty cycles. © 2011 American Chemical Society.

  17. Energy efficient recovery and dehydration of ethanol from fermentation broths by Membrane Assisted Vapor Stripping technology (United States)

    Distillation combined with molecular sieve dehydration is the current state of the art for fuel grade ethanol production from fermentation broths. To improve the sustainability of bioethanol production, energy efficient separation alternatives are needed, particularly for lower ...

  18. Cane molasses fermentation for continuous ethanol production in an immobilized cells reactor by Saccharomyces cerevisiae

    Energy Technology Data Exchange (ETDEWEB)

    Ghorbani, Farshid; Younesi, Habibollah; Esmaeili Sari, Abbas [Department of Environmental Science, Faculty of Natural Resources and Marine Sciences, Tarbiat Modares University, Noor, P.O. Box: 64414-356 (Iran); Najafpour, Ghasem [Department of Chemical Engineering, Faculty of Engineering, Noshirvani University of Technology, Babol (Iran)


    Sodium-alginate immobilized yeast was employed to produce ethanol continuously using cane molasses as a carbon source in an immobilized cell reactor (ICR). The immobilization of Saccharomyces cerevisiae was performed by entrapment of the cell cultured media harvested at exponential growth phase (16 h) with 3% sodium alginate. During the initial stage of operation, the ICR was loaded with fresh beads of mean diameter of 5.01 mm. The ethanol production was affected by the concentration of the cane molasses (50, 100 and 150 g/l), dilution rates (0.064, 0.096, 0.144 and 0.192 h{sup -1}) and hydraulic retention time (5.21, 6.94, 10.42 and 15.63 h) of the media. The pH of the feed medium was set at 4.5 and the fermentation was carried out at an ambient temperature. The maximum ethanol production, theoretical yield (Y{sub E/S}), volumetric ethanol productivity (Q{sub P}) and total sugar consumption was 19.15 g/l, 46.23%, 2.39 g l{sup -1} h{sup -1} and 96%, respectively. (author)

  19. Ethanol fermentation of a diluted molasses medium by Saccharomyces cerevisiae immobilized on chrysotile

    Directory of Open Access Journals (Sweden)

    Monte Alegre Ranulfo


    Full Text Available In this work, the catalytic role of chrysotile support on the acceleration of alcoholic fermentation under non-aseptic conditions by Saccharomyces cerevisiae was investigated. The fermentation medium employed consisted only of diluted sugar-cane molasses. In the batch fermentations process with immobilized yeasts, the initial rate of CO2 production increased roughly 27 % during the first 30 minutes, compared to systems containing no chrysotile. A study of continuous alcoholic fermentation with chrysotile in the reactor bed showed a higher ethanol production rate at the different dilution rates investigated compared to similar fermentations without chrysotile.

  20. The preparation and ethanol fermentation of high-concentration sugars from steam-explosion corn stover. (United States)

    Xie, Hui; Wang, Fengqin; Yin, Shuangyao; Ren, Tianbao; Song, Andong


    In the field of biofuel ethanol, high-concentration- reducing sugars made from cellulosic materials lay the foundation for high-concentration ethanol fermentation. In this study, corn stover was pre-treated in a process combining chemical methods and steam explosion; the cellulosic hydrolyzed sugars obtained by fed-batch saccharification were then used as the carbon source for high-concentration ethanol fermentation. Saccharomyces cerevisiae 1308, Angel yeast, and Issatchenkia orientalis were shake-cultured with Pachysolen tannophilus P-01 for fermentation. Results implied that the ethanol yields from the three types of mixed strains were 4.85 g/100 mL, 4.57 g/100 mL, and 5.02 g/100 mL (separately) at yield rates of 91.6, 89.3, and 92.2%, respectively. Therefore, it was inferred that shock-fermentation using mixed strains achieved a higher ethanol yield at a greater rate in a shorter fermentation period. This study provided a theoretical basis and technical guidance for the fermentation of industrial high-concentrated cellulosic ethanol.

  1. Characteristics of an immobilized yeast cell system using very high gravity for the fermentation of ethanol. (United States)

    Ji, Hairui; Yu, Jianliang; Zhang, Xu; Tan, Tianwei


    The characteristics of ethanol production by immobilized yeast cells were investigated for both repeated batch fermentation and continuous fermentation. With an initial sugar concentration of 280 g/L during the repeated batch fermentation, more than 98% of total sugar was consumed in 65 h with an average ethanol concentration and ethanol yield of 130.12 g/L and 0.477 g ethanol/g consumed sugar, respectively. The immobilized yeast cell system was reliable for at least 10 batches and for a period of 28 days without accompanying the regeneration of Saccharomyces cerevisiae inside the carriers. The multistage continuous fermentation was carried out in a five-stage column bioreactor with a total working volume of 3.75 L. The bioreactor was operated for 26 days at a dilution rate of 0.015 h(-1). The ethanol concentration of the effluent reached 130.77 g/L ethanol while an average 8.18 g/L residual sugar remained. Due to the high osmotic pressure and toxic ethanol, considerable yeast cells died without regeneration, especially in the last two stages, which led to the breakdown of the whole system of multistage continuous fermentation.

  2. Biofilm formation and ethanol inhibition by bacterial contaminants of biofuel fermentation (United States)

    Bacterial contaminants can inhibit ethanol production in biofuel fermentations, and even result in stuck fermentations. Contaminants may persist in production facilities by forming recalcitrant biofilms. A two-year longitudinal study was conducted of bacterial contaminants from a Midwestern dry grin...

  3. Bacteriophage-encoded lytic enzymes control growth of contaminating Lactobacillus found in fuel ethanol fermentations (United States)

    Background: Reduced yields of ethanol due to bacterial contamination in fermentation cultures weakens the economics of biofuel production. Lactic acid bacteria are considered the most problematic, and surveys of commercial fuel ethanol facilities have found that species of Lactobacillus are predomin...

  4. Suitability of anaerobic digestion effluent as process water for corn fuel ethanol fermentation. (United States)

    Wang, Ke; Zhang, Jian-Hua; Liu, Pei; Mao, Zhong-Gui


    A corn fuel ethanol plant integrated with anaerobic digestion treatment of thin stillage increases the net energy balance. Furthermore, the anaerobic digestion effluent (ADE) can be reused as a potential substitute for process water in the ethanol fermentation. In this study, the suitability of ADE as process water for corn ethanol fermentation was investigated by analyzing the potential inhibitory components in the ADE. It was found that ammonium influenced the growth and metabolism of Saccharomyces cerevisiae. Maximum ethanol production was obtained when the concentration of ammonium nitrogen was 200 mg/L, and ammonium could replace urea as the nitrogen source for S. cerevisiae under this concentration. In the ethanol fermentation with a higher concentration of ammonium, more glycerol was produced, thereby resulting in the decrease of ethanol production. In addition, components except ammonium in the ADE caused no inhibition to ethanol production. These results suggest that ADE could be reused as process water for corn ethanol fermentation without negative effect when ammonium concentration is well controlled.

  5. Lower-cost cellulosic ethanol production using cellobiose fermenting yeast Clavispora NRRL Y-50464 (United States)

    For ethanol production from cellulosic materials, there are generally two major steps needed including enzymatic hydrolysis to break down biomass sugars and microbial fermentation to convert available simple sugars into ethanol. It often requires two different kinds of microorganisms since ethanolog...

  6. Synthesis of Bio-Ethanol from Corn Stalk by Fermentation Process

    Directory of Open Access Journals (Sweden)

    Y. C. Wong


    Full Text Available Ethanol synthesis from corn stalk through fermentation process was studied. The ethanol produced was studied by various enzymatic treatment temperature and different feedstock loading in term of weight. The result shows that the highest concentration of ethanol contained in the sample was 48.90% at enzymatic temperature of 50°C. The temperature for optimum enzyme treatment have been identified as 50°C followed by 30, 40 and 60°C respectively.

  7. Fed-batch simultaneous saccharification and ethanol fermentation of native corn starch

    Directory of Open Access Journals (Sweden)

    Włodzimierz Grajek


    Full Text Available Background. The most important innovations in boethanol production in the last decade were: simultaneous saccharification and fermentation processes (SSF, high gravity fermentation, the use of new enzyme preparation able to hydrolyse native granular starch and construction of genetically modified strains of microorganisms able to carry out simultaneous production of hydrolytic enzymes and fermentation of C6 and C5 sugars. The aim of this study was to assess the efficiency of ethanol fermentation using new type of amylolytic enzymes able to hydrolyse native corn starch in a SSF process. Material and methods. The simultaneous saccharification and fermentation of raw corn flour by fed-batch processes using Saccharomyces cerevisiae strain Red Star Ethanol Red and Stargen 001 enzyme preparation was performed. As experimental variable were investigated: fermentation temperature (35-37-40°C, rate of mash stirring (100 and 200 rpm, fermentation time (0-92 h and dosage of corn flour (different portion and different time. Results. It was found that optimal temperature for fed-batch SSF process was 37°C at initial pH of 5.0. However, the yeast intensively fermented the saccharides also at 40°C. The fermentation stirring rate has significant effect on starch utilization and fermentation production. The prolongation of fermentation time over 72 h has no substantiation in additional ethanol production. In all experimental fermentations the level of produced organic acids was very low, significantly below toxic concentration for the yeast. Conclusions. It was stated that the use of new method of starch raw material preparation resulted in satisfied fermentation yield and allowed to reduce energy requirements for starch liquefaction.  

  8. Ethanol fermentation of uncooked sweet potato with the application of enzymes

    Energy Technology Data Exchange (ETDEWEB)

    Svendsby, O. (Mahidol Univ., Bangkok, Thailand); Kakutani, K.; Matsumura, Y.; Iizuka, M.; Yamamoto, T.


    An attempt was made to simplify the ethanol fermentation of sweet potato tubers by using enzymes. The potato tubers were sterilized with acid, minced, and incubated at room temperature with enzymes and yeast. The ethanol fermentation of the mash proceeded along with saccharification of starch, and the ethanol produced after 5 days of incubation was estimated to be 100 g by weight per kg potato tubers. Pectin depolymerase was observed to allow glucoamylase to act easily on starch by reducing the viscosity of the incubation mash.

  9. Pre-treatment step with Leuconostoc mesenteroides or L. pseudomesenteroides strains removes furfural from Zymomonas mobilis ethanolic fermentation broth. (United States)

    Hunter, William J; Manter, Daniel K


    Furfural is an inhibitor of growth and ethanol production by Zymomonas mobilis. This study used a naturally occurring (not GMO) biological pre-treatment to reduce that amount of furfural in a model fermentation broth. Pre-treatment involved inoculating and incubating the fermentation broth with strains of Leuconostoc mesenteroides or Leuconostoc pseudomesenteroides. The Leuconostoc strains converted furfural to furfuryl alcohol without consuming large amounts of dextrose in the process. Coupling this pre-treatment to ethanolic fermentation reduced furfural in the broth and improved growth, dextrose uptake and ethanol formation. Pre-treatment permitted ethanol formation in the presence of 5.2 g L(-1) furfural, which was otherwise inhibitive. The pre-treatment and presence of the Leuconostoc strains in the fermentation broth did not interfere with Z. mobilis ethanolic fermentation or the amounts of ethanol produced. The method suggests a possible technique for reducing the effect that furfural has on the production of ethanol for use as a biofuel.

  10. Sequential Fermentation with Selected Immobilized Non-Saccharomyces Yeast for Reduction of Ethanol Content in Wine. (United States)

    Canonico, Laura; Comitini, Francesca; Oro, Lucia; Ciani, Maurizio


    The average ethanol content of wine has increased over the last two decades. This increase was due to consumer preference, and also to climate change that resulted in increased grape maturity at harvest. In the present study, to reduce ethanol content in wine, a microbiological approach was investigated, using immobilized selected strains of non-Saccharomyces yeasts namely Starmerella bombicola, Metschnikowia pulcherrima, Hanseniaspora osmophila, and Hanseniaspora uvarum to start fermentation, followed by inoculation of free Saccharomyces cerevisiae cells. The immobilization procedures, determining high reaction rates, led a feasible sequential inoculation management avoiding possible contamination under actual winemaking. Under these conditions, the immobilized cells metabolized almost 50% of the sugar in 3 days, while S. cerevisiae inoculation completed all of fermentation. The S. bombicola and M. pulcherrima initial fermentations showed the best reductions in the final ethanol content (1.6 and 1.4% v/v, respectively). Resulting wines did not have any negative fermentation products with the exception of H. uvarum sequential fermentation that showed significant amount of ethyl acetate. On the other hand, there were increases in desirable compounds such as glycerol and succinic acid for S. bombicola, geraniol for M. pulcherrima and isoamyl acetate and isoamyl alcohol for H. osmophila sequential fermentations. The overall results indicated that a promising ethanol reduction could be obtained using sequential fermentation of immobilized selected non-Saccharomyces strains. In this way, a suitable timing of second inoculation and an enhancement of analytical profile of wine were obtained.

  11. Sequential fermentation with selected immobilized non-Saccharomyces yeast for reduction of ethanol content in wine

    Directory of Open Access Journals (Sweden)

    Laura eCanonico


    Full Text Available The average ethanol content of wine has increased over the last two decades. This increase was due to consumer preference, and also to climate change that resulted in increased grape maturity at harvest. In the present study, to reduce ethanol content in wine, a microbiological approach was investigated using immobilized selected strains of non-Saccharomyces yeasts namely Starmerella bombicola, Metschnikowia pulcherrima, Hanseniaspora osmophila and Hanseniaspora uvarum to start fermentation, followed by inoculation of free Saccharomyces cerevisiae cells. The immobilization procedures, determining high reaction rates, led a feasible sequential inoculation management avoiding possible contamination under actual winemaking. Under these conditions, the immobilized cells metabolized almost 50% of the sugar in 3 days, while S. cerevisiae inoculation completed all of fermentation. The S. bombicola and M. pulcherrima initial fermentations showed the best reductions in the final ethanol content (1.6% and 1.4% v/v, respectively. Resulting wines did not have any negative fermentation products with the exception of H. uvarum sequential fermentation that showed significant amount of ethyl acetate. On the other hand, there were increases in desirable compounds such as glycerol and succinic acid for S. bombicola, geraniol for M. pulcherrima and isoamyl acetate and isoamyl alcohol for H. osmophila sequential fermentations. The overall results indicated that a promising ethanol reduction could be obtained using sequential fermentation of immobilized selected non-Saccharomyces strains. In this way, a suitable timing of second inoculation and an enhancement of analytical profile of wine were obtained.

  12. Bioconversion of renewable resources into ethanol: An economic evaluation of selected hydrolysis, fermentation, and membrane technologies

    Energy Technology Data Exchange (ETDEWEB)

    Qureshi, N. [Univ. of Nebraska, Lincoln, NE (United States). Dept. of Biological Systems Engineering; Manderson, G.J. [Massey Univ., Palmerston North (New Zealand). Dept. of Process and Environmental Technology


    Four renewable agricultural resources were considered in a process design analysis for the industrial production of ethanol. Raw materials considered were wood, molasses, whey permeate, and starch. Final fermentation substrates were diluted and/or concentrated to give equivalent sugar concentrations for each case. Renewable resource costs were expressed as $/kg of sugar rather than /kg of the raw material. Molasses sugars were cheaper than sugars derived from the other raw materials. Various fermentation technologies were considered, including continuous culture and cell recycle. Ethanol recovery was examined using pervaporation and costs compared with distillation. The effects on ethanol prices of raw material costs, fermentation technology, product recovery, tax, plant size, and Lang factor are presented. Cultures of Candida shehatae, Zymomonas mobilis, Kluyveromyces marxianus var. lactis and Saccharomyces cerevisiae (with Zymomonas mobilis) were used, depending on the substrate. The report identifies the most appropriate technologies in terms of final ethanol price.

  13. Ethanol production from banana peels using statistically optimized simultaneous saccharification and fermentation process. (United States)

    Oberoi, Harinder Singh; Vadlani, Praveen V; Saida, Lavudi; Bansal, Sunil; Hughes, Joshua D


    Dried and ground banana peel biomass (BP) after hydrothermal sterilization pretreatment was used for ethanol production using simultaneous saccharification and fermentation (SSF). Central composite design (CCD) was used to optimize concentrations of cellulase and pectinase, temperature and time for ethanol production from BP using SSF. Analysis of variance showed a high coefficient of determination (R(2)) value of 0.92 for ethanol production. On the basis of model graphs and numerical optimization, the validation was done in a laboratory batch fermenter with cellulase, pectinase, temperature and time of nine cellulase filter paper unit/gram cellulose (FPU/g-cellulose), 72 international units/gram pectin (IU/g-pectin), 37 °C and 15 h, respectively. The experiment using optimized parameters in batch fermenter not only resulted in higher ethanol concentration than the one predicted by the model equation, but also saved fermentation time. This study demonstrated that both hydrothermal pretreatment and SSF could be successfully carried out in a single vessel, and use of optimized process parameters helped achieve significant ethanol productivity, indicating commercial potential for the process. To the best of our knowledge, ethanol concentration and ethanol productivity of 28.2 g/l and 2.3 g/l/h, respectively from banana peels have not been reported to date.

  14. Ethanol concentration in food and body condition affect foraging behavior in Egyptian fruit bats ( Rousettus aegyptiacus) (United States)

    Sánchez, Francisco; Korine, Carmi; Kotler, Burt P.; Pinshow, Berry


    Ethanol occurs in fleshy fruit as a result of sugar fermentation by both microorganisms and the plant itself; its concentration [EtOH] increases as fruit ripens. At low concentrations, ethanol is a nutrient, whereas at high concentrations, it is toxic. We hypothesized that the effects of ethanol on the foraging behavior of frugivorous vertebrates depend on its concentration in food and the body condition of the forager. We predicted that ethanol stimulates food consumption when its concentration is similar to that found in ripe fruit, whereas [EtOH] below or above that of ripe fruit has either no effect, or else deters foragers, respectively. Moreover, we expected that the amount of food ingested on a particular day of feeding influences the toxic effects of ethanol on a forager, and consequently shapes its feeding decisions on the following day. We therefore predicted that for a food-restricted forager, ethanol-rich food is of lower value than ethanol-free food. We used Egyptian fruit bats ( Rousettus aegyptiacus) as a model to test our hypotheses, and found that ethanol did not increase the value of food for the bats. High [EtOH] reduced the value of food for well-fed bats. However, for food-restricted bats, there was no difference between the value of ethanol-rich and ethanol-free food. Thus, microorganisms, via their production of ethanol, may affect the patterns of feeding of seed-dispersing frugivores. However, these patterns could be modified by the body condition of the animals because they might trade-off the costs of intoxication against the value of nutrients acquired.

  15. Effect of microbial pretreatment on enzymatic hydrolysis and fermentation of cotton stalks for ethanol production

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Jian; Sharma-Shivappa, Ratna R.; Chinn, Mari [Department of Biological and Agricultural Engineering, Campus Box 7625, North Carolina State University, Raleigh, NC 27695-7625 (United States); Howell, Noura [North Carolina School of Science and Mathematics, Durham, NC 27715 (United States)


    The potential of microbial pretreatment of cotton stalks by Phanerochaete chrysosporium to degrade lignin and facilitate fuel ethanol production was investigated under two culture conditions: submerged cultivation (SmC) and solid state (SSC) cultivation. Although microbial pretreatments showed significant lignin degradation (LD) (19.38% and 35.53% for SmC and SSC, respectively), a study on hydrolysis and fermentation of the microbial-pretreated cotton stalks showed no increase in cellulose conversion (10.98% and 3.04% for SmC and SSC pretreated samples, respectively) compared to untreated cotton stalks (17.93%). Solid state cultivation demonstrated better selectivity of 0.82 than 0.70 with submerged pretreatment. Washing of pretreated cotton stalks did not significantly increase cellulose conversion. However, heating and washing remarkably improved (P<0.05) cellulose conversion to 14.94% and 17.81% for SmC and SSC 14 day pretreatment, respectively. Ethanol yields, up to 0.027 g ethanol g{sup -1} initial cotton stalks, were low for all untreated and pretreated samples mainly due to the low cellulose conversion. Although potential and some critical aspects of fungal pretreatment using P. chrysosporium have been explored in this study, additional investigation is still required especially to improve the selectivity for preferential LD and to optimize hydrolysis efficiency. The mechanism of catalytic binding of cellulolytic enzymes to cotton stalks as affected by the presence of fungal mycelia also warrants further study. (author)

  16. A Mathematical model for ethanol production by extractive fermentation in a continuous stirred tank fermentor. (United States)

    Kollerup, F; Daugulis, A J


    Extractive fermentation is a technique that can be used to reduce the effect of end product inhibition through the use of a water-immiscible phase that removes fermentation products in situ. This has the beneficial effect of not only removing inhibitory products as they are formed (thus keeping reaction rates high) but also has the potential for reducing product recovery costs. We have chosen to examine the ethanol fermentation as a model system for end product inhibition and extractive fermentation and have developed a computer model predicting the productivity enhancement possible with this technique together with other key parameters such as extraction efficiency and residual glucose concentration. The model accommodates variable liquid flowrates entering and leaving the system, since it was found that the aqueous outlet flowrate could be up to 35% lower than the inlet flowrate during extractive fermentation of concentrated glucose feeds due to the continuous removal of ethanol from the fermentation broth by solvent extraction. The model predicts a total ethanol productivity of 82.6 g/L h if a glucose feed of 750 g/L is fermented with a solvent having a distribution coefficient of 0.5 at a solvent dilution rate of 5.0 h(-1). This is more than 10 times higher than for a conventional chemostat fermentation of a 250 g/L glucose feed. The model has furthermore illustrated the possible trade-offs that exist between obtaining a high extraction efficiency and a low residual glucose concentration.

  17. Effect of air supplement on the performance of continuous ethanol fermentation system. (United States)

    Ryu, D D; Kim, Y J; Kim, J H


    For the purpose of improving ethanol productivity, the effect of air supplement on the performance of continuous ethanol fermentation system was studied. The effect of oxygen supplement on yeast concentration, cell yield, cell viability, extracellular ethanol concentration, ethanol yield, maintenance coefficient, specific rates of glucose assimilation, ethanol production, and ethanol productivity have been evaluated, using a high alcohol tolerant Saccharomyces cerevisiae STV89 strain and employing a continuous fermentor equipped with an accurate air metering system in the flow rate range 0-11 mL air/L/h. It was found that, when a small amount of oxygen up to about 80mu mol oxygen/L/h was supplied, the ethanol productivity was significantly enhanced as compared to the productivity of the culture without any air supplement. It was also found that the oxygen supplement improved cell viability considerably as well as the ethanol tolerance level of yeast. As the air supply rate was increased, from 0 to 11 mL air/L/h while maintaining a constant dilution rate at about 0.06 h(-1), the cell concentration increased from 2.3 to 8.2 g/L and the ethanol productivity increased from 1.7 to 4.1 g ethanol/L/h, although the specific ethanol production rate decreased slightly from 0.75 to 0.5 g ethanol/g cell/h. The ethanol yield was slightly improved also with an increase in air supply rate, from about 0.37 to 0.45 ethanol/g glucose. The maintenance coefficient increased by only a small amount with the air supplement. This kind of air supplement technique may very well prove to be of practical importance to a development of a highly productive ethanol fermentation process system especially as a combined system with a high density cell culture technique.

  18. Increased expression of the yeast multidrug resistance ABC transporter Pdr18 leads to increased ethanol tolerance and ethanol production in high gravity alcoholic fermentation

    Directory of Open Access Journals (Sweden)

    Teixeira Miguel C


    Full Text Available Abstract Background The understanding of the molecular basis of yeast tolerance to ethanol may guide the design of rational strategies to increase process performance in industrial alcoholic fermentations. A set of 21 genes encoding multidrug transporters from the ATP-Binding Cassette (ABC Superfamily and Major Facilitator Superfamily (MFS in S. cerevisiae were scrutinized for a role in ethanol stress resistance. Results A yeast multidrug resistance ABC transporter encoded by the PDR18 gene, proposed to play a role in the incorporation of ergosterol in the yeast plasma membrane, was found to confer resistance to growth inhibitory concentrations of ethanol. PDR18 expression was seen to contribute to decreased 3 H-ethanol intracellular concentrations and decreased plasma membrane permeabilization of yeast cells challenged with inhibitory ethanol concentrations. Given the increased tolerance to ethanol of cells expressing PDR18, the final concentration of ethanol produced during high gravity alcoholic fermentation by yeast cells devoid of PDR18 was lower than the final ethanol concentration produced by the corresponding parental strain. Moreover, an engineered yeast strain in which the PDR18 promoter was replaced in the genome by the stronger PDR5 promoter, leading to increased PDR18 mRNA levels during alcoholic fermentation, was able to attain a 6 % higher ethanol concentration and a 17 % higher ethanol production yield than the parental strain. The improved fermentative performance of yeast cells over-expressing PDR18 was found to correlate with their increased ethanol tolerance and ability to restrain plasma membrane permeabilization induced throughout high gravity fermentation. Conclusions PDR18 gene over-expression increases yeast ethanol tolerance and fermentation performance leading to the production of highly inhibitory concentrations of ethanol. PDR18 overexpression in industrial yeast strains appears to be a promising approach to

  19. Medium Optimization for Improved Ethanol Production in Very High Gravity Fermentation

    Institute of Scientific and Technical Information of China (English)

    胡纯铿; 秦晴; 高培培


    An optimal medium (300 g·L^-1 initial glucose) comprising 6.3 mmol·L^-1 Mg2+, 5.0 mmol·L^-1 Ca2+, 15.0 g·L^-1 peptone and 21.5 g·L^-1 yeast extract was determined by uniform design to improve very high gravity (VHG) ethanol fermentation, showing over 30% increase in final ethanol (from 13.1% to 17.1%, by volume), 29% decrease in fermentation time (from 84 to 60 h), 80% increase in biomass formation and 26% increase in glucose utilization. Experiments also revealed physiological aspects linked to the fermentation enhancements. Compared to the control, trehalose in the cells grown in optimal fermentation medium increased 17.9-, 2.8-, 1.9-, 1.8- and 1.9-fold at the fermentation time of 12, 24, 36, 48 and 60 h, respectively. Its sharp rise at the early stage of fermentation when there was a considerable osmotic stress suggested that trehalose played an important role in promoting fermentation. Meanwhile, at the identical five fermentation time, the plasma membrane ATPase activity of the cells grown in optimal medium was 2.3, 1.8, 1.6, 1.5 and 1.3 times that of the control, respectively. Their disparities in enzymatic activity became wider when the glucose levels were dramatically changed for ethanol production, suggesting this enzyme also contributed to the fermentation improvements. Thus, medium optimization for VHG ethanol fermentation was found to trigger the increased yeast trehalose accumulation and plasma membrane ATPase activity.

  20. Hydrogen energy recovery from high strength organic wastewater with ethanol type fermentation using acidogenic EGSB reactor

    Institute of Scientific and Technical Information of China (English)

    REN Nan-qi; GUO Wan-qian; WANG Xiang-jing; ZHANG Lu-si


    A lab-scale expanded granular sludge bed (EGSB) reactor was employed to evaluate the feasibility of the hydrogen energy recovery potential from high strength organic wastewater. The results showed that a maxioperation. At the acidogenic phase, COD removal rate was stable at about 15%. In the steady operation peri od, the main liquid end products were ethanol and acetic acid, which represented ethanol type fermentation. Among the liquid end products, the concentration percentage of ethanol and acetic acid amounted to 69.5% ~89.8% and the concentration percentage of ethanol took prominent about 51.7% ~ 59.1%, which is better than the utilization of substrate for the methanogenic bacteria. An ethanol type fermentation pathway was suggested in the operation of enlarged industrial continuous hydrogen bio-producing reactors.

  1. Elucidating the roles of ethanol fermentation metabolism in causing off-flavors in mandarins. (United States)

    Tietel, Zipora; Lewinsohn, Efraim; Fallik, Elazar; Porat, Ron


    To elucidate the roles of ethanol fermentation metabolism in causing off-flavors, 'Mor' mandarins were exposed to anaerobic atmospheres for 0, 2, 4, 7, and 10 days to gradually increase juice ethanol and acetaldehyde levels through enhanced fermentation. Exposure to anaerobic atmosphere caused progressive decline in fruit sensory quality, from nearly "good" to "very bad", because of decreased typical mandarin flavor and increased sensation of 'musty' and 'ethanol' off-flavors. GC-MS analysis revealed significant (p ≤ 0.05) increases in the contents of 12 aroma volatiles, including the ethanol fermentation metabolites ethanol and acetaldehyde, and several fatty acid and amino acid catabolism derivates, 7 of which were ethyl esters, which suggests that they were esterification products of ethanol and acyl-CoA's derived from fatty acid and amino acid catabolism. These de novo synthesized anaerobiosis-regulated ethyl esters impart 'pungent', 'ethereal', 'waxy', 'musty', and 'fruity' notes. Overall, these results suggest that besides the direct effects of ethanol and acetaldehyde, downstream ethanol esterification products may also be involved in causing off-flavor sensation in mandarins.

  2. Ethanol fermentation of energy beets by self-flocculating and non-flocculating yeasts. (United States)

    Zhang, Ningning; Steven Green, V; Ge, Xumeng; Savary, Brett J; Xu, Jianfeng


    Specialized varieties of sugar beets (Energy Beets™) are being developed for producing industrial sugars in Arkansas' Mississippi River Delta. To evaluate their suitability for producing regional fermentation feedstocks, we report initial cultivation trials and ethanol fermentation of raw beet juice and combined juice with pulp mash (JPM) liquefied with enzymes, comparing ethanol yields under different regimes by self-flocculating and non-flocculating yeasts. Nine varieties produced root yields averaging 115Mg/ha and 18.5% sucrose contents. Raw beet juice fermentation yielded ethanol up to 0.48g/g (sugar). JPM was directly fermented through either a sequential (SeqSF) or simultaneous saccharification and fermentation (SSF) process. For both yeast types, SSF was a more efficient process than SeqSF, with ethanol yields up to 0.47g/g (sugar) and volumetric productivity up to 7.81g/L/h. These results indicate the self-flocculating yeast is suitable for developing efficient bioprocesses to ferment industrial sugar from energy beets.

  3. Direct fermentation of d-xylose to ethanol by Kluyveromyces marxianus strains

    Energy Technology Data Exchange (ETDEWEB)

    Margaritis, A.; Bajpai, P.


    Eight strains of Kluyveromyces marxianus were screened, and all of them were found to ferment the aldopentose D-xylose directly to ethanol under aerobic conditions. One of these strains, K. marxianus SUB-80-S, was grown in a medium containing 20 g of D-xylose per liter, and the following results were obtained: maximum ethanol concentration, 5.6 g/liter; ethanol yield, 0.28 g of ethanol per g of D-xylose (55% of theoretical); maximum specific growth rate, 0.12/hour; 100% D-xylose utilization was completed in 48 hours. (Refs. 12).

  4. Ethanol production from wet oxidized corn straw by simultaneous saccharification and fermentation

    DEFF Research Database (Denmark)

    Zhang, Q.; Yin, Y.; Thygesen, Anders


    In order to find out the appropriate process for ethanol production from corn straw, alkaline wet-oxidation pretreatment (195°C, 15 min, Na2CO3 2 g/L, O2 1200 kPa) and simultaneous saccharification and fermentation (SSF) were adopted to produce ethanol. The results showed that 90% of cellulose...... was obtained. The estimated total ethanol production was 262.7 kg/t raw material by assuming the consumption of both C-6 and C-5. No obvious inhibition effect occurred during SSF. These offered experiment evidences for ethanol production from corn straw....

  5. Effect of Steam Explosion Pretreatment on Bamboo for Enzymatic Hydrolysis and Ethanol Fermentation

    Directory of Open Access Journals (Sweden)

    Zhiqiang Li


    Full Text Available Based on the steam explosion pretreatment that has been applied to other types of lignocellulosic biomass, the steam explosion pretreatment of bamboo, along with a study of the chemical compositions and enzymatic hydrolyzability of substrates, was conducted. The results show that steam explosion pretreatment can greatly enhance the cellulose-to-glucose conversion yield after enzymatic hydrolysis, which is sometimes affected by bamboo age and steam explosion conditions. When the steam explosion pretreatment conditions were 2.0 MPa (pressure and 4 min (time, the cellulose-to-glucose conversion yield of 2-year-old bamboo substrate was 62.5%. However, the cellulose-to-glucose conversion yield of bamboo substrates after direct (without steam explosion pretreatment sodium chlorite/acetic acid delignification was 93.1%. Fermentation of enzymatic hydrolyzates with Saccharomyces cerevisiae resulted in about 88.1% to 96.2% of the corresponding theoretical ethanol yield after 24 h.

  6. Effect of acetic acid in recycling water on ethanol production for cassava in an integrated ethanol-methane fermentation process. (United States)

    Yang, Xinchao; Wang, Ke; Zhang, Jianhua; Tang, Lei; Mao, Zhonggui


    Recently, the integrated ethanol-methane fermentation process has been studied to prevent wastewater pollution. However, when the anaerobic digestion reaction runs poorly, acetic acid will accumulate in the recycling water. In this paper, we studied the effect of low concentration of acetic acid (≤25 mM) on ethanol fermentation at different initial pH values (4.2, 5.2 or 6.2). At an initial pH of 4.2, ethanol yields increased by 3.0% and glycerol yields decreased by 33.6% as the acetic acid concentration was increased from 0 to 25 mM. Raising the concentration of acetic acid to 25 mM increased the buffering capacity of the medium without obvious effects on biomass production in the cassava medium. Acetic acid was metabolized by Saccharomyces cerevisiae for the reason that the final concentration of acetic acid was 38.17% lower than initial concentration at pH 5.2 when 25 mM acetic acid was added. These results confirmed that a low concentration of acetic acid in the process stimulated ethanol fermentation. Thus, reducing the acetic acid concentration to a controlled low level is more advantageous than completely removing it.

  7. Ethanol Sensitization during Adolescence or Adulthood Induces Different Patterns of Ethanol Consumption without Affecting Ethanol Metabolism (United States)

    Carrara-Nascimento, Priscila F.; Hoffmann, Lucas B.; Contó, Marcos B.; Marcourakis, Tania; Camarini, Rosana


    In previous study, we demonstrated that ethanol preexposure may increase ethanol consumption in both adolescent and adult mice, in a two-bottle choice model. We now questioned if ethanol exposure during adolescence results in changes of consumption pattern using a three-bottle choice procedure, considering drinking-in-the-dark and alcohol deprivation effect as strategies for ethanol consumption escalation. We also analyzed aldehyde dehydrogenase (ALDH) activity as a measurement of ethanol metabolism. Adolescent and adult Swiss mice were treated with saline (SAL) or 2.0 g/kg ethanol (EtOH) during 15 days (groups: Adolescent-SAL, Adolescent-EtOH, Adult-SAL and Adult-EtOH). Five days after the last injection, mice were exposed to the three-bottle choice protocol using sucrose fading procedure (4% + sucrose vs. 8%–15% ethanol + sucrose vs. water + sucrose) for 2 h during the dark phase. Sucrose was faded out from 8% to 0%. The protocol was composed of a 6-week acquisition period, followed by four withdrawals and reexposures. Both adolescent and adult mice exhibited ethanol behavioral sensitization, although the magnitude of sensitization in adolescents was lower than in adults. Adolescent-EtOH displayed an escalation of 4% ethanol consumption during acquisition that was not observed in Adult-EtOH. Moreover, Adult-EtOH consumed less 4% ethanol throughout all the experiment and less 15% ethanol in the last reexposure period than Adolescent-EtOH. ALDH activity varied with age, in which older mice showed higher ALDH than younger ones. Ethanol pretreatment or the pattern of consumption did not have influence on ALDH activity. Our data suggest that ethanol pretreatment during adolescence but not adulthood may influence the pattern of ethanol consumption toward an escalation in ethanol consumption at low dose, without exerting an impact on ALDH activity.

  8. Influence of calcium ion on ethanol tolerance of Saccharomyces bayanus and alcoholic fermentation by yeasts

    Energy Technology Data Exchange (ETDEWEB)

    Nabais, R.C.; Sa-Correia, I.; Viegas, C.A.; Novais, J.M. (Instituto Superior Tecnico, Lisbon (Portugal))


    The addition of Ca{sup 2+} (as CaCl{sub 2}) in optimal concentrations (0.75 to 2.0 mM) to a fermentation medium with a trace contaminating concentration of Ca{sup 2+} (0.025 mM) led to the rapid production of higher concentrations of ethanol by Saccharomyces cerevisiae, Saccharomyces bayanus, and Kluyveromyces marxianus. The positive effect of calcium supplementation (0.75 mM) on alcoholic fermentation by S. bayanus was explained by the increase in its ethanol tolerance. For lethal concentrations of ethanol, the specific death rates were minimal for cells that were grown and incubated with ethanol in medium with an optimal concentration of Ca{sup 2+}, maximal for cells grown and incubated with ethanol in unsupplemented medium, and intermediate for cells grown in unsupplemented medium and incubated with ethanol in calcium-supplemented medium. The effect of Ca{sup 2+} on the acidification curve of energized cells in the presence of ethanol was found to be closely associated with its protective effect on growth, fermentation, and viability.

  9. Ethanol from Whey: Continuous Fermentation with a Catabolite Repression-Resistant Saccharomyces cerevisiae Mutant. (United States)

    Terrell, S L; Bernard, A; Bailey, R B


    An alternative method for the conversion of cheese whey lactose into ethanol has been demonstrated. With the help of continuous-culture technology, a catabolite repression-resistant mutant of Saccharomyces cerevisiae completely fermented equimolar mixtures of glucose and galactose into ethanol. The first step in this process was a computer-controlled fed-batch operation based on the carbon dioxide evolution rate of the culture. In the absence of inhibitory ethanol concentrations, this step allowed us to obtain high biomass concentrations before continuous fermentation. The continuous anaerobic process successfully incorporated a cell-recycle system to optimize the fermentor productivity. Under conditions permitting a low residual sugar concentration (fermentation of highly concentrated feed solutions (20%) was also demonstrated, but only with greatly diminished fermentor productivity (5.5 g liter h).

  10. Enhanced bioprocessing of lignocellulose: Wood-rot fungal saccharification and fermentation of corn fiber to ethanol (United States)

    Shrestha, Prachand

    This research aims at developing a biorefinery platform to convert corn-ethanol coproduct, corn fiber, into fermentable sugars at a lower temperature with minimal use of chemicals. White-rot (Phanerochaete chrysosporium), brown-rot (Gloeophyllum trabeum) and soft-rot (Trichoderma reesei) fungi were used in this research to biologically break down cellulosic and hemicellulosic components of corn fiber into fermentable sugars. Laboratory-scale simultaneous saccharification and fermentation (SSF) process proceeded by in-situ cellulolytic enzyme induction enhanced overall enzymatic hydrolysis of hemi/cellulose from corn fiber into simple sugars (mono-, di-, tri-saccharides). The yeast fermentation of hydrolyzate yielded 7.1, 8.6 and 4.1 g ethanol per 100 g corn fiber when saccharified with the white-, brown-, and soft-rot fungi, respectively. The highest corn-to-ethanol yield (8.6 g ethanol/100 g corn fiber) was equivalent to 42 % of the theoretical ethanol yield from starch and cellulose in corn fiber. Cellulase, xylanase and amylase activities of these fungi were also investigated over a week long solid-substrate fermentation of corn fiber. G. trabeum had the highest activities for starch (160 mg glucose/mg protein.min) and on day three of solid-substrate fermentation. P. chrysosporium had the highest activity for xylan (119 mg xylose/mg protein.min) on day five and carboxymethyl cellulose (35 mg glucose/mg protein.min) on day three of solid-substrate fermentation. T. reesei showed the highest activity for Sigma cell 20 (54.8 mg glucose/mg protein.min) on day 5 of solid-substrate fermentation. The effect of different pretreatments on SSF of corn fiber by fungal processes was examined. Corn fiber was treated at 30 °C for 2 h with alkali [2% NaOH (w/w)], alkaline peroxide [2% NaOH (w/w) and 1% H2O 2 (w/w)], and by steaming at 100 °C for 2 h. Mild pretreatment resulted in improved ethanol yields for brown- and soft-rot SSF, while white-rot and Spezyme CP SSFs showed

  11. Bioconversion of sugarcane biomass into ethanol: an overview about composition, pretreatment methods, detoxification of hydrolysates, enzymatic saccharification, and ethanol fermentation. (United States)

    Canilha, Larissa; Kumar Chandel, Anuj; dos Santos Milessi, Thais Suzane; Fernandes Antunes, Felipe Antônio; da Costa Freitas, Wagner Luiz; das Graças Almeida Felipe, Maria; da Silva, Silvio Silvério


    Depleted supplies of fossil fuel, regular price hikes of gasoline, and environmental damage have necessitated the search for economic and eco-benign alternative of gasoline. Ethanol is produced from food/feed-based substrates (grains, sugars, and molasses), and its application as an energy source does not seem fit for long term due to the increasing fuel, food, feed, and other needs. These concerns have enforced to explore the alternative means of cost competitive and sustainable supply of biofuel. Sugarcane residues, sugarcane bagasse (SB), and straw (SS) could be the ideal feedstock for the second-generation (2G) ethanol production. These raw materials are rich in carbohydrates and renewable and do not compete with food/feed demands. However, the efficient bioconversion of SB/SS (efficient pretreatment technology, depolymerization of cellulose, and fermentation of released sugars) remains challenging to commercialize the cellulosic ethanol. Among the technological challenges, robust pretreatment and development of efficient bioconversion process (implicating suitable ethanol producing strains converting pentose and hexose sugars) have a key role to play. This paper aims to review the compositional profile of SB and SS, pretreatment methods of cane biomass, detoxification methods for the purification of hydrolysates, enzymatic hydrolysis, and the fermentation of released sugars for ethanol production.

  12. Bioconversion of Sugarcane Biomass into Ethanol: An Overview about Composition, Pretreatment Methods, Detoxification of Hydrolysates, Enzymatic Saccharification, and Ethanol Fermentation

    Directory of Open Access Journals (Sweden)

    Larissa Canilha


    Full Text Available Depleted supplies of fossil fuel, regular price hikes of gasoline, and environmental damage have necessitated the search for economic and eco-benign alternative of gasoline. Ethanol is produced from food/feed-based substrates (grains, sugars, and molasses, and its application as an energy source does not seem fit for long term due to the increasing fuel, food, feed, and other needs. These concerns have enforced to explore the alternative means of cost competitive and sustainable supply of biofuel. Sugarcane residues, sugarcane bagasse (SB, and straw (SS could be the ideal feedstock for the second-generation (2G ethanol production. These raw materials are rich in carbohydrates and renewable and do not compete with food/feed demands. However, the efficient bioconversion of SB/SS (efficient pretreatment technology, depolymerization of cellulose, and fermentation of released sugars remains challenging to commercialize the cellulosic ethanol. Among the technological challenges, robust pretreatment and development of efficient bioconversion process (implicating suitable ethanol producing strains converting pentose and hexose sugars have a key role to play. This paper aims to review the compositional profile of SB and SS, pretreatment methods of cane biomass, detoxification methods for the purification of hydrolysates, enzymatic hydrolysis, and the fermentation of released sugars for ethanol production.

  13. Changes of Saccharomyces cerevisiae cell membrane components and promotion to ethanol tolerance during the bioethanol fermentation. (United States)

    Dong, Shi-Jun; Yi, Chen-Feng; Li, Hao


    During bioethanol fermentation process, Saccharomyces cerevisiae cell membrane might provide main protection to tolerate accumulated ethanol, and S. cerevisiae cells might also remodel their membrane compositions or structure to try to adapt to or tolerate the ethanol stress. However, the exact changes and roles of S. cerevisiae cell membrane components during bioethanol fermentation still remains poorly understood. This study was performed to clarify changes and roles of S. cerevisiae cell membrane components during bioethanol fermentation. Both cell diameter and membrane integrity decreased as fermentation time lasting. Moreover, compared with cells at lag phase, cells at exponential and stationary phases had higher contents of ergosterol and oleic acid (C18:1) but lower levels of hexadecanoic (C16:0) and palmitelaidic (C16:1) acids. Contents of most detected phospholipids presented an increase tendency during fermentation process. Increased contents of oleic acid and phospholipids containing unsaturated fatty acids might indicate enhanced cell membrane fluidity. Compared with cells at lag phase, cells at exponential and stationary phases had higher expressions of ACC1 and HFA1. However, OLE1 expression underwent an evident increase at exponential phase but a decrease at following stationary phase. These results indicated that during bioethanol fermentation process, yeast cells remodeled membrane and more changeable cell membrane contributed to acquiring higher ethanol tolerance of S. cerevisiae cells. These results highlighted our knowledge about relationship between the variation of cell membrane structure and compositions and ethanol tolerance, and would contribute to a better understanding of bioethanol fermentation process and construction of industrial ethanologenic strains with higher ethanol tolerance.

  14. Application in the Ethanol Fermentation of Immobilized Yeast Cells in Matrix of Alginate/Magnetic Nanoparticles, on Chitosan-Magnetite Microparticles and Cellulose-coated Magnetic Nanoparticles

    CERN Document Server

    Ivanova, Viara; Hristov, Jordan


    Saccharomyces cerevisiae cells were entrapped in matrix of alginate and magnetic nanoparticles and covalently immobilized on magnetite-containing chitosan and cellulose-coated magnetic nanoparticles. Cellulose-coated magnetic nanoparticles with covalently immobilized thermostable {\\alpha}-amylase and chitosan particles with immobilized glucoamylase were also prepared. The immobilized cells and enzymes were applied in column reactors - 1/for simultaneous corn starch saccharification with the immobilized glucoamylase and production of ethanol with the entrapped or covalently immobilized yeast cells, 2/ for separate ethanol fermentation of the starch hydrolysates with the fixed yeasts. Hydrolysis of corn starch with the immobilized {\\alpha}-amylase and glucoamylase, and separate hydrolysis with the immobilized {\\alpha}-amylase were also examined. In the first reactor the ethanol yield reached approx. 91% of the theoretical; the yield was approx. 86% in the second. The ethanol fermentation was affected by the typ...

  15. Production of ethanol from mesquite [Prosopis juliflora (SW) D.C.] pods mash by Zymomonas mobilis in submerged fermentation

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Celiane Gomes Maia da [Universidade Federal Rural de Pernambuco (UFRPE), Recife, PE (Brazil). Dept. de Ciencias Domesticas; Andrade, Samara Alvachian Cardoso; Schuler, Alexandre Ricardo Pereira [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Engenharia Quimica; Souza, Evandro Leite de [Universidade Federal da Paraiba (UFPB), Joao Pessoa, PB (Brazil). Dept. de Nutricao; Stamford, Tania Lucia Montenegro [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Nutricao], E-mail:


    Mesquite [Prosopis juliflora (SW) D.C.], a perennial tropical plant commonly found in Brazilian semi-arid region, is a viable raw material for fermentative processes because of its low cost and production of pods with high content of hydrolyzable sugars which generate many compounds, including ethanol. This study aimed to evaluate the use of mesquite pods as substrate for ethanol production by Z. mobilis UFPEDA- 205 in a submerged fermentation. The fermentation was assessed for rate of substrate yield to ethanol, rate of ethanol production and efficiency of fermentation. The very close theoretical (170 g L{sup -1}) and experimental (165 g L{sup -1}) maximum ethanol yields were achieved at 36 h of fermentation. The highest counts of Z. mobilis UFEPEDA-205 (both close to 6 Log cfu mL{sup -1}) were also noted at 36 h. Highest rates of substrate yield to ethanol (0.44 g ethanol g glucose{sup -1}), of ethanol production (4.69 g L{sup -1} h{sup -1}) and of efficiency of fermentation (86.81%) were found after 30 h. These findings suggest mesquite pods as an interesting substrate for ethanol production using submerged fermentation by Z. mobilis. (author)

  16. Influence of fermentation by-products on the purification of ethanol from water using pervaporation. (United States)

    Chovau, S; Gaykawad, S; Straathof, A J J; Van der Bruggen, B


    Pervaporation is claimed to be a promising separation technique for the purification of ethanol from fermentation broths during bio-ethanol production. In this study, influence of fermentation by-products on the purification of ethanol from water during hydrophobic pervaporation was investigated. Sugars and salts were found to increase the membrane performance. Reason for this was a change in vapor/liquid equilibrium. 2,3-butanediol decreased the ethanol flux and selectivity factor, while glycerol exhibited no effect. This was explained by a strong sorption of butanediol into PDMS and no sorption of glycerol. Due to the presence of carboxylic acids, hydrophobicity degree of the Pervap 4060 membrane decreased, which resulted in an irreversible increase in water flux and decrease in separation performance. These observations suggested the presence of silicalite-based fillers in the membrane. When the pH was raised to a value above the dissociation constant, no changes in hydrophobicity degree and membrane performance were found.

  17. Optimization of Wastewater Microalgae Pretreatment for Acetone, Butanol, and Ethanol Fermentation


    Castro, Yessica A.


    Acetone-butanol-ethanol (ABE) fermentation from wastewater microalgae by Clostridium saccharoperbutylacetonicum N1-4 is a novel bioprocess that utilizes waste substrate to generate valuable solvents. Butanol, the most abundant product resulting from ABE fermentation, is an environmentally safe and high performing fuel that can be utilized as a drop-in-fuel; however, high operational costs and low ABE yield present challenge in scale-up of the process. The utilization of algae as a substrate r...

  18. Simultaneous raw starch hydrolysis and ethanol fermentation by glucoamylase from Rhizoctonia solani and Saccharomyces cerevisiae. (United States)

    Singh, D; Dahiya, J S; Nigam, P


    Crude glucoamylase preparation from Rhizoctonia solani was used to saccharify raw and cooked starch. Various concentrations of potato starch and wheat flour from 10-40%, w/v were used for mashing but 30% was found to be the optimal and economical. The saccharified mash yielded 5.89%, v/v ethanol in a simultaneous saccharification and fermentation process using a yeast strain Saccharomyces cerevisiae (SC-39) at 35 degrees C for 4 days. Removal of inhibitory substances from the fermenting broth through dialysis caused considerable increase in ethanol production.

  19. Direct Fungal Production of Ethanol from High-Solids Pulps by the Ethanol-fermenting White-rot Fungus Phlebia sp. MG-60

    Directory of Open Access Journals (Sweden)

    Ichiro Kamei


    Full Text Available A white-rot fungus, Phlebia sp. MG-60, was applied to the fermentation of high-solid loadings of unbleached hardwood kraft pulp (UHKP without the addition of commercial cellulase. From 4.7% UHKP, 19.6 g L-1 ethanol was produced, equivalent to 61.7% of the theoretical maximum. The highest ethanol concentration (25.9 g L-1, or 46.7% of the theoretical maximum was observed in the culture containing 9.1% UHKP. The highest filter paper activity (FPase was observed in the culture containing 4.7% UHKP, while the production of FPase in the 16.5% UHKP culture was very low. Temporarily removing the silicone plug from Erlenmeyer flasks, which relieved the pressure and allowed a small amount of aeration, improved the yield of ethanol produced from the 9.1% UHKP, which reached as high as 37.3 g L-1. These results indicated that production of cellulase and ensuing saccharification and fermentation by Phlebia sp. MG-60 is affected by water content and benefits from a small amount of aeration.

  20. Inhibitory Effects of Biomass Degradation Products on Ethanol Fermentation and a Strategy to Overcome Them

    Directory of Open Access Journals (Sweden)

    Shiyu Fu


    Full Text Available The influence of buffers, as well as inhibitors such as formic acid, furfural, HMF, guaiacol, and vanillin, on ethanol formation was investigated. Compared to phosphoric buffer, the acetic and citric buffers were less inhibitory on ethanol fermentation. The addition of formic acid (2.5 g/L to the buffer reduced the ethanol yield by 8%. Guaiacol (3 g/L and vanillin (2.5 g/L decreased ethanol production by 50% and 20%, respectively. Furfural and HMF delayed the yeast fermentation without reducing the total yield. The fermentation was seriously inhibited by the mixture of furfural (1 g/L, HMF (1 g/L, formic acid (1 g/L, vanillin (1 g/L, and guaiacol (1 g/L. The ethanol yield of the fermentation based on enzymatic hydrolyzate from treated biomass was 82%. The addition of 1 g/L MgSO4 as a shielding protector rehabilitated nearly 100% of the total yield.

  1. Development of t(50) and its application to evaluate very-high-gravity ethanol fermentation. (United States)

    Lin, Yen-Han; Chang, Jen-Wei; Duan, Kow-Jen; Chang, Peter R


    A three-parameter logistic growth model was modified to monitor the glucose uptake profile of yeast during very-high-gravity (VHG) ethanol fermentation. The modified model was used to define t(50) as a quantifier to differentiate among various fermentation conditions. There are two types of t(50); t(50)(g) is the time required to convert 50% of the initial glucose, and t(50)(e) is the time required to produce half of the final ethanol. A 2(4) factorial experimental design was implemented to illustrate the applicability of using t(50) to isolate active ingredients in VHG growth media. The analytical results obtained from the experimental design and from a modified model were compared, which demonstrated that t(50) could serve the proposed objectives. A shorter t(50) implies a faster fermentation. A tailing of the ethanol profile after t(50)(e) indicates that there is an inhibitory effect imposed on yeast, i.e., the stronger the tailing in the ethanol profile, the stronger the inhibitory effect. When t(50) is equal to or near to the halftime of the total course of the fermentation, a bell-shaped curve was seen for the glucose uptake rate or for the ethanol production rate, indicating that the inhibitory effect exerted on yeast was evenly distributed.

  2. The use of a thermotolerant fermentative Kluyveromyces marxianus IMB3 yeast strain for ethanol production

    Energy Technology Data Exchange (ETDEWEB)

    Banat, I.M. [Univ. of the United Arab Emirates, Al-Ain (United Arab Emirates). Dept. of Biolology; Singh, D. [Haryana Agriculture Univ., Hisar (India). Dept. of Microbiology; Marchant, R. [Ulster Univ. (United Kingdom). School of Applied Biological and Chemical Sciences


    An investigation was carried out on the growth and ethanol production of a novel thermotolerant ethanol-producing Kluyveromyces marxianus IMB3 yeast strain. It grew aerobically on glucose, lactose, cellobiose, xylose and whey permeate and fermented all the above carbon sources to ethanol at 45 C. This strain was capable of growing under anaerobic chemostat fermentation conditions at 45 C and a dilution rate of 0.15 h{sup -1} and produced {<=}0.9 g/l biomass and 1.8% (v/v) ethanol. An increase in biomass (up to 10.0 g/l) and ethanol (up to 4.3% v/v at 45 C and 7.7% v/v at 40 C) were achieved by applying a continuous two-stage fermentation in sequence (one aerobic and one anerobic stage) or a two-stage anaerobic fermentation with cell recycling. Potential applications, involving alcohol production systems, for use in dairy and wood related industries, were discussed. (orig.)

  3. Immobilized ethanol fermentation coupled to pervaporation with silicalite-1/polydimethylsiloxane/polyvinylidene fluoride composite membrane. (United States)

    Cai, Di; Hu, Song; Chen, Changjing; Wang, Yong; Zhang, Changwei; Miao, Qi; Qin, Peiyong; Tan, Tianwei


    A novel silicalite-1/polydimethylsiloxane/polyvinylidene fluoride hybrid membrane was used in ethanol fermentation-pervaporation integration process. The sweet sorghum bagasse was used as the immobilized carrier. Compared with the conventional suspend cells system, the immobilized fermentation system could provide higher ethanol productivity when coupled with pervaporation. In the long-term of operations, the ethanol productivity, separation factor, total flux and permeate ethanol concentration in the fed-batch fermentation-pervaporation integration scenario were 1.6g/Lh, 8.2-9.9, 319-416g/m(2)h and 426.9-597.2g/L, respectively. Correspondingly, 1.6g/Lh, 7.8-9.8, 227.8-395g/m(2)h and 410.9-608.1g/L were achieved in the continuous fermentation-pervaporation integration scenario, respectively. The results indicated that the integration process could greatly improve the ethanol production and separation performances.

  4. Fermentation guide for potatoes. A step-by-step procedure for small-scale ethanol fuel production

    Energy Technology Data Exchange (ETDEWEB)


    This guide describes the steps involved in the successful batch starch conversion and fermentation of potatoes for the production of fuel grade ethanol. The first part of this manual provides an overview of ethanol production from feedstock to fermentation. The second part of the manual is a recipe section that gives step-by-step procedures necessary for successful fermentation. Chapter titles are: major steps in ethanol production; equipment and chemicals; water testing and treatment; feedstock cleaning and crushing; precooking; hydration and dextrinization; cooking; choosing the best enzymes; fermentation; core and cleaning, step-by-step procedure; refinements; and supplies. (DMC)

  5. High ethanol fermentation performance of the dry dilute acid pretreated corn stover by an evolutionarily adapted Saccharomyces cerevisiae strain. (United States)

    Qureshi, Abdul Sattar; Zhang, Jian; Bao, Jie


    Ethanol fermentation was investigated at the high solids content of the dry dilute sulfuric acid pretreated corn stover feedstock using an evolutionary adapted Saccharomyces cerevisiae DQ1 strain. The evolutionary adaptation was conducted by successively transferring the S. cerevisiae DQ1 cells into the inhibitors containing corn stover hydrolysate every 12h and finally a stable yeast strain was obtained after 65 days' continuous adaptation. The ethanol fermentation performance using the adapted strain was significantly improved with the high ethanol titer of 71.40 g/L and the high yield of 80.34% in the simultaneous saccharification and fermentation (SSF) at 30% solids content. No wastewater was generated from pretreatment to fermentation steps. The results were compared with the published cellulosic ethanol fermentation cases, and the obvious advantages of the present work were demonstrated not only at the high ethanol titer and yield, but also the significant reduction of wastewater generation and potential cost reduction.

  6. Ethanol fermentation from xylose by metabolically engineered strains of Kluyveromyces marxianus. (United States)

    Goshima, Tetsuya; Negi, Kanako; Tsuji, Masaharu; Inoue, Hiroyuki; Yano, Shinichi; Hoshino, Tamotsu; Matsushika, Akinori


    We constructed a xylose-fermenting recombinant strain of thermotolerant yeast Kluyveromyces marxianus, DMB3-7. Both xylose consumption and ethanol production were remarkably increased in DMB3-7 compared to the control strain at 30°C. Furthermore, DMB3-7 produced ethanol from xylose at both 42°C and 45°C, above which xylose metabolic activity decreased.

  7. Impact of high temperature on ethanol fermentation by Kluyveromyces marxianus immobilized on banana leaf sheath pieces. (United States)

    Le, Hoang Du; Thanonkeo, Pornthap; Le, Van Viet Man


    Ethanol fermentation was carried out with Kluyveromyces marxianus cells at various temperatures (30, 35, 40, and 45 °C). Fermentation performance of the immobilized yeast on banana leaf sheath pieces and the free yeast were evaluated and compared. Generally, ethanol production of the immobilized and free yeast was stable in a temperature range of 30-40 °C. Temperature of 45 °C restricted yeast growth and lengthened the fermentation. The immobilized yeast demonstrated faster sugar assimilation and higher ethanol level in the fermentation broth in comparison with the free yeast at all fermentation temperatures. Change in fatty acid level in cellular membrane was determined to clarify the response of the free and immobilized yeast to thermal stress. The free cells of K. marxianus responded to temperature increase by increasing saturated fatty acid (C16:0 and C18:0) level and by decreasing unsaturated fatty acid (C18:1 and C18:2) level in cellular membrane. For fermentation at 40 °C with immobilized cells of K. marxianus, however, the changes were not observed in both saturated fatty acid (C16:0) and unsaturated fatty acid (C18:1 and C18:2) level.

  8. Redox potential driven aeration during very-high-gravity ethanol fermentation by using flocculating yeast. (United States)

    Liu, Chen-Guang; Hao, Xue-Mi; Lin, Yen-Han; Bai, Feng-Wu


    Ethanol fermentation requires oxygen to maintain high biomass and cell viability, especially under very-high-gravity (VHG) condition. In this work, fermentation redox potential (ORP) was applied to drive the aeration process at low dissolved oxygen (DO) levels, which is infeasible to be regulated by a DO sensor. The performance and characteristics of flocculating yeast grown under 300 and 260 g glucose/L conditions were subjected to various aeration strategies including: no aeration; controlled aeration at -150, -100 and -50 mV levels; and constant aeration at 0.05 and 0.2 vvm. The results showed that anaerobic fermentation produced the least ethanol and had the highest residual glucose after 72 h of fermentation. Controlled aerations, depending on the real-time oxygen demand, led to higher cell viability than the no-aeration counterpart. Constant aeration triggered a quick biomass formation, and fast glucose utilization. However, over aeration at 0.2 vvm caused a reduction of final ethanol concentration. The controlled aeration driven by ORP under VHG conditions resulted in the best fermentation performance. Moreover, the controlled aeration could enhance yeast flocculating activity, promote an increase of flocs size, and accelerate yeast separation near the end of fermentation.

  9. Effect of inhibitors formed during wheat straw pretreatment on ethanol fermentation by Pichia stipitis. (United States)

    Bellido, Carolina; Bolado, Silvia; Coca, Mónica; Lucas, Susana; González-Benito, Gerardo; García-Cubero, María Teresa


    The inhibitory effect of the main inhibitors (acetic acid, furfural and 5-hydroxymethylfurfural) formed during steam explosion of wheat straw was studied through ethanol fermentations of model substrates and hydrolysates from wheat straw by Pichia stipitis. Experimental results showed that an increase in acetic acid concentration led to a reduction in ethanol productivity and complete inhibition was observed at 3.5 g/L. Furfural produced a delay on sugar consumption rates with increasing concentration and HMF did not exert a significant effect. Fermentations of the whole slurry from steam exploded wheat straw were completely inhibited by a synergistic effect due to the presence of 1.5 g/L acetic acid, 0.15 g/L furfural and 0.05 g/L HMF together with solid fraction. When using only the solid fraction from steam explosion, hydrolysates presented 0.5 g/L of acetic acid, whose fermentations have submitted promising results, providing an ethanol yield of 0.45 g ethanol/g sugars and the final ethanol concentration reached was 12.2 g/L (10.9 g ethanol/100 g DM).

  10. A novel approach for the improvement of ethanol fermentation by Saccharomyces cerevisiae

    Energy Technology Data Exchange (ETDEWEB)

    Hou, L.; Cao, X.; Wang, C. [Tianjin Univ. of Science and Technology, Tianjin (China). Key Laboratory of Food Nutrition and Safety


    The partial substitution of fossil fuels with bioethanol has become an important strategy for the use of renewable energy. Ethanol production is generally achieved through fermentation of starch or sugar-based feedstock by Saccharomyces cerevisiae. In order to meet the growing demand for ethanol, there is a need for new yeast strains that can produce ethanol more efficiently and cost effectively. This paper presented a new genome engineering approach that was developed to improve ethanol production by S. cerevisiae. In this study, the aneuploid strain constructed on the base of tetraploid cells was shown to have favourable metabolic traits in very high gravity (VHG) fermentation with 300 g/L glucose as the carbon source. The tetraploid strain was constructed using the plasmid YCplac33-GHK, which comprised the HO gene encoding the site-specific HO endonucleases. The aneuploid strain, WT4-M, was chosen and screened once the tetraploid cells were treated with methyl benzimidazole-2-yl-carbamate to induce loss of mitotic chromosomes. The aneuploid strain WT4-M increased ethanol production as well as osmotic and thermal tolerance. The sugar to ethanol conversion rate also improved. It was concluded that this new approach is valuable for creating yeast strains with better fermentation characteristics. 25 refs., 3 figs.

  11. Characterization of a recombinant flocculent Saccharomyces cerevisiae strain that co-ferments glucose and xylose: II. influence of pH and acetic acid on ethanol production. (United States)

    Matsushika, Akinori; Sawayama, Shigeki


    The inhibitory effects of pH and acetic acid on the co-fermentation of glucose and xylose in complex medium by recombinant flocculent Saccharomyces cerevisiae MA-R4 were evaluated. In the absence of acetic acid, the fermentation performance of strain MA-R4 was similar between pH 4.0-6.0, but was negatively affected at pH 2.5. The addition of acetic acid to batch cultures resulted in negligible inhibition of several fermentation parameters at pH 6.0, whereas the interactive inhibition of pH and acetic acid on the maximum cell and ethanol concentrations, and rates of sugar consumption and ethanol production were observed at pH levels below 5.4. The inhibitory effect of acetic acid was particularly marked for the consumption rate of xylose, as compared with that of glucose. With increasing initial acetic acid concentration, the ethanol yield slightly increased at pH 5.4 and 6.0, but decreased at pH values lower than 4.7. Notably, ethanol production was nearly completely inhibited under low pH (4.0) and high acetic acid (150-200 mM) conditions. Together, these results indicate that the inhibitory effects of acetic acid and pH on ethanol fermentation by MA-R4 are highly synergistic, although the inhibition can be reduced by increasing the medium pH.

  12. Effects of pretreatment methods for hazelnut shell hydrolysate fermentation with Pichia Stipitis to ethanol. (United States)

    Arslan, Yeşim; Eken-Saraçoğlu, Nurdan


    In this study, we investigated the use of hazelnut shell as a renewable and low cost lignocellulosic material for bioethanol production for the first time. High lignin content of hazelnut shell is an important obstacle for such a biotransformation. Biomass hydrolysis with acids yields reducing sugar with several inhibitors which limit the fermentability of sugars. The various conditioning methods for biomass and hydrolysate were performed to overcome the toxicity and their effects on the subsequent fermentation of hazelnut shell hydrolysate by Pichia stipitis were evaluated with shaking flasks experiments. Hazelnut shells hydrolysis with 0.7M H(2)SO(4) yielded 49 gl(-1) total reducing sugars and fermentation inhibitors in untreated hydrolysate. First, it was shown that several hydrolysate detoxification methods were solely inefficient in achieving cell growth and ethanol production in the fermentation of hazelnut shell hydrolysates derived from non-delignified biomass. Next, different pretreatments of hazelnut shells were considered for delignification and employed before hydrolysis in conjunction with hydrolysate detoxification to improve alcohol fermentation. Among six delignification methods, the most effective pretreatment regarding to ethanol concentration includes the treatment of shells with 3% (w/v) NaOH at room temperature, which was integrated with sequential hydrolysate detoxification by overliming and then treatment with charcoal twice at 60 degrees C. This treatment brought about a total reduction of 97% in furans and 88.4% in phenolics. Almost all trialed treatments caused significant sugar loss. Under the best assayed conditions, ethanol concentration of 16.79gl(-1) was reached from a hazelnut shell hyrolysate containing initial 50g total reducing sugar l(-1) after partial synthetic xylose supplementation. This value is equal to 91.25% of ethanol concentration that was obtained from synthetic d-xylose under same conditions. The present study

  13. Recent progress on industrial fermentative production of acetone-butanol-ethanol by Clostridium acetobutylicum in China. (United States)

    Ni, Ye; Sun, Zhihao


    China is one of the few countries, which maintained the fermentative acetone-butanol-ethanol (ABE) production for several decades. Until the end of the last century, the ABE fermentation from grain was operated in a few industrial scale plants. Due to the strong competition from the petrochemical industries, the fermentative ABE production lost its position in the 1990s, when all the solvent fermentation plants in China were closed. Under the current circumstances of concern about energy limitations and environmental pollution, new opportunities have emerged for the traditional ABE fermentation industry since it could again be potentially competitive with chemical synthesis. From 2006, several ABE fermentation plants in China have resumed production. The total solvent (acetone, butanol, and ethanol) production capacity from ten plants reached 210,000 tons, and the total solvent production is expected to be extended to 1,000,000 tons (based on the available data as of Sept. 2008). This article reviews current work in strain development, the continuous fermentation process, solvent recovery, and economic evaluation of ABE process in China. Challenges for an economically competitive ABE process in the future are also discussed.

  14. Thermophilic Dry Methane Fermentation of Distillation Residue Eluted from Ethanol Fermentation of Kitchen Waste and Dynamics of Microbial Communities. (United States)

    Huang, Yu-Lian; Tan, Li; Wang, Ting-Ting; Sun, Zhao-Yong; Tang, Yue-Qin; Kida, Kenji


    Thermophilic dry methane fermentation is advantageous for feedstock with high solid content. Distillation residue with 65.1 % moisture content was eluted from ethanol fermentation of kitchen waste and subjected to thermophilic dry methane fermentation, after adjusting the moisture content to 75 %. The effect of carbon to nitrogen (C/N) ratio on thermophilic dry methane fermentation was investigated. Results showed that thermophilic dry methane fermentation could not be stably performed for >10 weeks at a C/N ratio of 12.6 and a volatile total solid (VTS) loading rate of 1 g/kg sludge/d; however, it was stably performed at a C/N ratio of 19.8 and a VTS loading rate of 3 g/kg sludge/d with 83.4 % energy recovery efficiency. Quantitative PCR analysis revealed that the number of bacteria and archaea decreased by two orders of magnitude at a C/N ratio of 12.6, whereas they were not influenced at a C/N ratio of 19.8. Microbial community analysis revealed that the relative abundance of protein-degrading bacteria increased and that of organic acid-oxidizing bacteria and acetic acid-oxidizing bacteria decreased at a C/N ratio of 12.6. Therefore, there was accumulation of NH4(+) and acetic acid, which inhibited thermophilic dry methane fermentation.

  15. Novel DDR Processing of Corn Stover Achieves High Monomeric Sugar Concentrations from Enzymatic Hydrolysis (230 g/L) and High Ethanol Concentration (10% v/v) During Fermentation

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xiaowen; Jennings, Ed; Shekiro, Joe; Kuhn, Erik M.; O' Brien, Marykate; Wang, Wei; Schell, Daniel J.; Himmel, Mike; Elander, Richard T.; Tucker, Melvin P.


    Distilling and purifying ethanol, butanol, and other products from second and later generation lignocellulosic biorefineries adds significant capital and operating cost for biofuels production. The energy costs associated with distillation affects plant gate and life cycle analysis costs. Lower titers in fermentation due to lower sugar concentrations from pretreatment increase both energy and production costs. In addition, higher titers decrease the volumes required for enzymatic hydrolysis and fermentation vessels. Therefore, increasing biofuels titers has been a research focus in renewable biofuels production for several decades. In this work, we achieved over 200 g/L of monomeric sugars after high solids enzymatic hydrolysis using the novel deacetylation and disc refining (DDR) process on corn stover. The high sugar concentrations and low chemical inhibitor concentrations from the DDR process allowed ethanol titers as high as 82 g/L in 22 hours, which translates into approximately 10 vol% ethanol. To our knowledge, this is the first time that 10 vol% ethanol in fermentation derived from corn stover without any sugar concentration or purification steps has been reported. Techno-economic analysis shows the higher titer ethanol achieved from the DDR process could significantly reduce the minimum ethanol selling price from cellulosic biomass.

  16. Fuel cell-based instrumentation for ethanol determination in alcoholic beverages, fermentations, and biofluids

    Energy Technology Data Exchange (ETDEWEB)

    Parry, K.W.


    The main aim of this project was to devise an alternative method for ethanol assay, employing an electrochemical fuel cell sensor. Thus, the early part of this thesis describes the work carried out in the development of a new analytical technique for this purpose. This work resulted in the production of a successful prototype unit which has led to the development of a commercial instrument, vis., the Lion Drinks Alcolmeter (DA-1) available from Lion Laboratories Ltd. The problem of determining the ethanol content of a fermenting liquor at any point during a fermentation process was also broached and a novel technique combining a flow dilution system, dynamic headspace analysis and a fuel cell sensor was developed. This procedure, suitably automated, will enable the ethanolic content of a fermenting beverage to be determined at any stage during a fermentation, the results obtained in this manner being in excellent agreement with those obtained gas chromatographically. Methods of extending the linear working range of a fuel cell-based sampling system are reported in the hope that the encouraging results obtained may initiate further progress in this field. Finally, the sensing system used in this work has also been utilized with an alternative sampling procedure for the determination of ethanol in biological fluids, mainly for clinical and forensic applications. This work has also led to the production of a commercial instrument, viz. the Lion AE-D3 Alcolmeter.

  17. State Estimation in Fermentation of Lignocellulosic Ethanol. Focus on the Use of pH Measurements

    DEFF Research Database (Denmark)

    Mauricio Iglesias, Miguel; Gernaey, Krist; Huusom, Jakob Kjøbsted


    The application of the continuous-discrete extended Kalman filter (CD-EKF) as a powerful tool for state estimation in biochemical systems is assessed here. Using a fermentation process for ethanol production as a case study, the CD-EKF can effectively estimate the model states even when highly non...

  18. Fermentation of glycerol into ethanol in a microbial electrolysis cell driven by a customized consortium. (United States)

    Speers, Allison M; Young, Jenna M; Reguera, Gemma


    The in situ generation of ethanol from glycerol-containing wastewater shows promise to improve the economics of the biodiesel industry. Consequently, we developed a microbial electrolysis cell (MEC) driven by the synergistic metabolisms of the exoelectrogen Geobacter sulfurreducens and the bacterium Clostridium cellobioparum, which fermented glycerol into ethanol in high yields (90%) and produced fermentative byproducts that served as electron donors for G. sulfurreducens. Syntrophic cooperation stimulated glycerol consumption, ethanol production, and the conversion of fermentation byproducts into cathodic H2 in the MEC. The platform was further improved by adaptively evolving glycerol-tolerant strains with robust growth at glycerol loadings typical of biodiesel wastewater and by increasing the buffering capacity of the anode medium. This resulted in additional increases in glycerol consumption (up to 50 g/L) and ethanol production (up to 10 g/L) at rates that greatly exceeded the capacity of the anode biofilms to concomitantly remove the fermentation byproducts. As a result, 1,3-propanediol was generated as a metabolic sink for electrons not converted into electricity syntrophically. The results highlight the potential of consortia to process glycerol in MECs and provide insights into genetic engineering and system design approaches that can be implemented to further improve MEC performance to satisfy industrial needs.

  19. Simultaneous saccharification and fermentation of industrial sweetpotatoes for ethanol production and anthocyanins extraction (United States)

    A simultaneous saccharification fermentation (SSF) system was studied for ethanol production in flour industrial sweetpotato (ISP) feedstocks (lines: white DM02-180 and purple NC-413) as an integrated cost saving process, and to examine the feasibility of extracting anthocyanins from flour purple IS...

  20. Ethanol fermentation of molasses by Saccharomyces cerevisiae cells immobilized onto sugar beet pulp

    Directory of Open Access Journals (Sweden)

    Vučurović Vesna M.


    Full Text Available Natural adhesion of Saccharomyces cerevisiae onto sugar beet pulp (SBP is a very simple and cheap immobilization method for retaining high cells density in the ethanol fermentation system. In the present study, yeast cells were immobilized by adhesion onto SBP suspended in the synthetic culture media under different conditions such as: glucose concentration (100, 120 and 150 g/l, inoculum concentration (5, 10 and 15 g/l dry mass and temperature (25, 30, 35 and 40°C. In order to estimate the optimal immobilization conditions the yeast cells retention (R, after each immobilization experiment was analyzed. The highest R value of 0.486 g dry mass yeast /g dry mass SBP was obtained at 30°C, glucose concentration of 150 g/l, and inoculum concentration of 15 g/l. The yeast immobilized under these conditions was used for ethanol fermentation of sugar beet molasses containing 150.2 g/l of reducing sugar. Efficient ethanol fermentation (ethanol concentration of 70.57 g/l, fermentation efficiency 93.98% of sugar beet molasses was achieved using S. cerevisiae immobilized by natural adhesion on SBP. [Projekat Ministarstva nauke Republike Srbije, br. TR-31002

  1. Sorghum Protein Extraction by Sonication and Its Relationship to Ethanol Fermentation (United States)

    The objectives of this research were to develop a rapid method for extracting proteins from mashed and non-mashed sorghum meal using sonication (ultrasound), and to determine the relationships between the levels of extractable proteins and ethanol fermentation. Nine grain sorghum samples with a bro...

  2. Variation of fermentation redox potential during cell-recycling continuous ethanol operation. (United States)

    Thani, Arthit; Lin, Yen-Han; Laopaiboon, Pattana; Laopaiboon, Lakkana


    Fermentation redox potential was monitored during cell-recycling continuous ethanol operation. The cell-recycling system (CRS) was operated using two hollow fibre (HF) membranes (pore sizes 0.20 and 0.65μm) at three dilution rates (0.02, 0.04 and 0.08h(-1)). Saccharomyces cerevisiae NP 01 were recycled in the fermenter at a recycle ratio of 0.625. Aeration was provided at 2.5vvm for the first 4h and then further supplied continuously at 0.25vvm. As steady state was established, results showed that the fermentation redox potential was lower for processes employing CRS than those without. At the same dilution rates, the sugar utilization and ethanol production with CRS were higher than those without CRS. The highest fermentation efficiency (87.94g/l of ethanol, ∼90% of theoretical yield) was achieved using a 0.2-μm HF membrane CRS at a dilution rate of 0.02h(-1). It was found that 7.53-10.07% of the carbon derived from glucose was incorporated into the yeast. Further, at the same dilution rates, yeast in the processes with CRS incorporated less carbon into ethanol than in those grown without CRS. This result suggests that processes involving CRS utilize more carbon for metabolite synthesis than biomass formation. This indicated that the processes with CRS could utilize more carbon for metabolite synthesis than biomass formation.

  3. High cell density cultures produced by internal retention: application in continuous ethanol fermentation

    Directory of Open Access Journals (Sweden)

    Berta Carola Pérez


    Full Text Available Ethanol has provoked great interest due to its potential as an alternative fuel. Nevertheless, fermentation processes must be developed by increasing the low volumetric productivity achieved in conventional cultures (batch or continuous to make this product become economically competitive. This can be achieved by using techniques leading to high cell concentration and reducing inhibition by the end-product. One of the frequently employed methods involves cell recycling. This work thus developed a membrane reactor incorporating a filtration module with 5 u,m stainless steel tubular units inside a 3L stirred jar fermenter for investigating its application in continuous ethanol production. The effects of cell concentration and transmembrane pressure difference on permeate flux were evaluated for testing the filtration module's performance. The internal cell retention system was operated in Saccharomyces cerevisiae continuous culture derived from sucrose, once fermentation conditions had been selected (30 °C, 1.25 -1.75 vvm, pH 4.5. Filter unit permeability was maintained by applying pulses of air. More than 97% of the grown cells were retained in the fermenter, reaching 51 g/L cell concentration and 8.51 g/L.h average ethanol productivity in culture with internal cell retention; this was twice that obtained in a conventional continuous culture. Key words: Membrane reactor, Saccharomyces cerevisiae, alcoholic fermentation, cell recycling.

  4. Influence of torrefaction pretreatment for ethanol fermentation from waste money bills. (United States)

    Sheikh, Md Mominul Islam; Kim, Chul-Hwan; Park, Hyeon-Jin; Kim, Sung-Ho; Kim, Gyeong-Chul; Lee, Ji-Young; Sim, Sung-Woong; Kim, Jae Won


    Waste money bills (WMB) that are no longer legal tender are nonrecyclable and are generally useless. In this work, we used this cellulose-rich material for ethanol fermentation for the first time. Torrefaction of this nonlignocellulosic waste material was attempted to examine whether such material could benefit from this process as a conventional lignocellulosic material does. Effects of two important parameters, that is, residence times (20, 40, and 60 Min) and temperatures (140, 160, 180, 200, and 220°C), on the torrefaction yield were studied under an inert atmosphere. Glucose and ethanol yields were compared using a factorial experimental design. The highest glucose yield (81.59 mg/mL) was obtained with a torrefaction treatment consisting of 40 min at 180 °C, and it was increased 44.89% compared to untreated WMB. Based on ethanol feasibility studies conducted on WMB, this estimated quantity of glucose could be produced for subsequent fermentation to ethanol (38.92 mg/mL) and it was increased 47.92% compared to the untreated sample. The fermentation rate was also enhanced by adding 0.4 mM benzoic acid under anaerobic conditions. It is concluded that production of ethanol from WMB would reduce waste management costs and thus would be profitable.

  5. Fermentation of xylose to produce ethanol by recombinant Saccharomyces cerevisiae strain containing XYLA and XKS1

    Institute of Scientific and Technical Information of China (English)

    LIU Xiaolin; JIANG Ning; HE Peng; LU Dajun; SHEN An


    Fermentation of the pentose sugar xylose to produce ethanol using lignocellulosic biomass would make bioethanol production economically more competitive. Saccharomyce cerevisise, an efficient ethanol producer, cannot utilize xylose because it lacks the ability to convert xylose to its isomer xylulose. In this study, XYLA gene encoding xylose isomerase (XI) from Thermoanaerobacter tengcongensis MB4T and XKS1 gene encoding xylulokinase (XK) from Pichia stipitis were cloned and functionally coexpressed in Saccharomyces cerevisiae EF-326 to construct a recombinant xylose-utilizing strain. The resulting strain S. cerevisiae EF 1014 not only grew on xylose as sole carbon source, but also produced ethanol under anaerobic conditions. Fermentations performed with different xylose concentrations at different temperatures demonstrated that the highest ethanol productivity was 0.11 g/g xylose when xylose concentration was provided at 50 g/L. Under this condition, 28.4% of xylose was consumed and 1.54 g/L xylitol was formed. An increasing fermentation temperature from 30℃ to 37℃ did not improve ethanol yield.

  6. Kinetic modeling of simultaneous saccharification and fermentation of corn starch for ethanol production. (United States)

    Białas, Wojciech; Czerniak, Adrian; Szymanowska-Powałowska, Daria


    Fuel ethanol production, using a simultaneous saccharification and fermentation process (SSF) of native starch from corn flour, has been performed using Saccharomyces cerevisiae and a granular starch hydrolyzing enzyme. The quantitative effects of mash concentration, enzyme dose and pH were investigated with the use of a Box-Wilson central composite design protocol. Proceeding from results obtained in optimal fermentation conditions, a kinetics model relating the utilization rates of starch and glucose as well as the production rates of ethanol and biomass was tested. Moreover, scanning electron microscopy (SEM) was applied to investigate corn starch granule surface after the SFF process. A maximum ethanol concentration of 110.36 g/l was obtained for native corn starch using a mash concentration of 25%, which resulted in ethanol yield of 85.71%. The optimal conditions for the above yield were found with an enzyme dose of 2.05 ml/kg and pH of 5.0. These results indicate that by using a central composite design, it is possible to determine optimal values of the fermentation parameters for maximum ethanol production. The investigated kinetics model can be used to describe SSF process conducted with granular starch hydrolyzing enzymes. The SEM micrographs reveal randomly distributed holes on the surface of granules.

  7. Effect of media supplementation on ethanol production by simultaneous saccharification and fermentation process

    Energy Technology Data Exchange (ETDEWEB)

    Ballesteros, I.; Oliva, J.M.; Carrasco, J.C.; Ballesteros, M. (IER-CIEMAT, Madrid (Spain))

    In this study, fermentation tests of different initial glucose concentrations, ranging from 100 to 200 g/L, were conducted to identify the ethanol tolerance of Kluyveromyces marxianus (EMS-26 strain) at 42[degrees]C. Lipid and nutrient additions to the fermentation medium were made in order to improve the ethanol production at 42[degrees]C. The results obtained showed that the addition of unsaturated fatty acids and sterols to the SSF media reduced hydrolysis yields and ethanol production as compared to tests carried out on controls without lipid supplementation. These results seem to indicate that cellulases performed better when no lipid supplementation was used. The decrease in the saccharification in the presence of 0.5% Tween 80 (10% decrease in the filter paper activity) seems to be closely related to the denaturation of the cellulase complex rather than lipids interference with cellulase binding. 22 refs., 4 figs., 2 tabs.

  8. Very high gravity (VHG) ethanolic brewing and fermentation: a research update. (United States)

    Puligundla, Pradeep; Smogrovicova, Daniela; Obulam, Vijaya Sarathi Reddy; Ko, Sanghoon


    There have been numerous developments in ethanol fermentation technology since the beginning of the new millennium as ethanol has become an immediate viable alternative to fast-depleting crude reserves as well as increasing concerns over environmental pollution. Nowadays, although most research efforts are focused on the conversion of cheap cellulosic substrates to ethanol, methods that are cost-competitive with gasoline production are still lacking. At the same time, the ethanol industry has engaged in implementing potential energy-saving, productivity and efficiency-maximizing technologies in existing production methods to become more viable. Very high gravity (VHG) fermentation is an emerging, versatile one among such technologies offering great savings in process water and energy requirements through fermentation of higher concentrations of sugar substrate and, therefore, increased final ethanol concentration in the medium. The technology also allows increased fermentation efficiency, without major alterations to existing facilities, by efficient utilization of fermentor space and elimination of known losses. This comprehensive research update on VHG technology is presented in two main sections, namely VHG brewing, wherein the effects of nutrients supplementation, yeast pitching rate, flavour compound synthesis and foam stability under increased wort gravities are discussed; and VHG bioethanol fermentation studies. In the latter section, aspects related to the role of osmoprotectants and nutrients in yeast stress reduction, substrates utilized/tested so far, including saccharide (glucose, sucrose, molasses, etc.) and starchy materials (wheat, corn, barley, oats, etc.), and mash viscosity issues in VHG bioethanol production are detailed. Thereafter, topics common to both areas such as process optimization studies, mutants and gene level studies, immobilized yeast applications, temperature effect, reserve carbohydrates profile in yeast, and economic aspects are

  9. Two Step Enzymatic Hydrolysis and Fermentation Strategy for Conversion of Acid Treated Hydrolysate of Corn Cob to Ethanol

    Directory of Open Access Journals (Sweden)

    *Geetanjali Swaroop Wakade


    Full Text Available For economic production of ethanol from corncobs, it is very crucial that lignocellulosic fractions containing glucose and xylose are simultaneously fermented to ethanol in a single operation i.e. cofermentation. Cofermentation of mixed acid treated corn cob hydrolysate containing mixed sugars at low concentration (<50 g L -1 using Pichia stipitis showed 92.35% ethanol fermentation efficiency. However cofermentation of corn cob hydrolysate comprising sugar above 50 g L-1 showed only 46.71% ethanol fermentation efficiency. Therefore a two step enzymatic hydrolysis and fermentation strategy was designed for cofermentation of corn cob hydrolysate containing high concentration of sugars which resulted in 86.74% enzymatic hydrolysis efficiency and 75.32% ethanol fermentation efficiency. Using two step hydrolysis and fermentation, there was 1.1 fold improvement in the enzymatic hydrolysis efficiency. Final ethanol concentration, ethanol yield and volumetric productivity were improved by 1.7, 1.66 and 2.6 fold respectively as compared to single step hydrolysis and fermentation process.

  10. Ethanol from lignocellulose - Fermentation inhibitors, detoxification and genetic engineering of Saccharomyces cerevisiae for enhanced resistance

    Energy Technology Data Exchange (ETDEWEB)

    Larsson, Simona


    Ethanol can be produced from lignocellulose by first hydrolysing the material to sugars, and then fermenting the hydrolysate with the yeast Saccharomyces cerevisiae. Hydrolysis using dilute sulphuric acid has advantages over other methods, however, compounds which inhibit fermentation are generated during this kind of hydrolysis. The inhibitory effect of aliphatic acids, furans, and phenolic compounds was investigated. The generation of inhibitors during hydrolysis was studied using Norway spruce as raw material. It was concluded that the decrease in the fermentability coincided with increasing harshness of the hydrolysis conditions. The decrease in fermentability was not correlated solely to the content of aliphatic acids or furan derivatives. To increase the fermentability, detoxification is often employed. Twelve detoxification methods were compared with respect to the chemical composition of the hydrolysate and the fermentability after treatment. The most efficient detoxification methods were anion-exchange at pH 10.0, overliming and enzymatic detoxification with the phenol-oxidase laccase. Detailed analyses of ion exchange revealed that anion exchange and unspecific hydrophobic interactions greatly contributed to the detoxification effect, while cation exchange did not. The comparison of detoxification methods also showed that phenolic compounds are very important fermentation inhibitors, as their selective removal with laccase had a major positive effect on the fermentability. Selected compounds; aliphatic acids, furans and phenolic compounds, were characterised with respect to their inhibitory effect on ethanolic fermentation by S. cerevisiae. When aliphatic acids or furans were compared, the inhibitory effects were found to be in the same range, but the phenolic compounds displayed widely different inhibitory effects. The possibility of genetically engineering S. cerevisiae to achieve increased inhibitor resistance was explored by heterologous expression of

  11. Metabolic engineering of the ethanol fermentation by Saccharomyces cerevisiae away from glycerol formation towards alternative products

    Energy Technology Data Exchange (ETDEWEB)

    Kumar Jain, V.; Divol, B.; Prior, B.; Franz Bauer, F. [Stellenbosch Univ., (South Africa). Inst. for Wine Biotechnology


    This study investigated the commercial advantage of eliminating glycerol from the ethanol fermentation process and possible replacement with other value products. Under fermentative conditions yeast re-oxidizes excess NADH through glycerol production which involves NADH-dependent glycerol-3-phosphate dehydrogenase. Deletion of these two genes renders the cells incapable of maintaining fermentative activity under anaerobic conditions due to accumulation of NADH. This study examined the feasibility of converting this excess NADH to Nad by transforming a glycerol synthesizing double mutant with genes that could restore the redox balance in the yeast. The study showed that although glycerol formation can be eliminated during fermentation, no alternative redox balancing pathway is as efficient at the glycerol pathway in maintaining fermentation. Alternative products such as sorbitol and 1,2propanediol can be produced instead of glycerol, but these genetic manipulations were shown to have negative effects on fermentative ability. Ethanol yields, but not concentrations, were improved in mutants. Significant amounts of acetate were also produced. This paper discussed the metabolic and biotechnological implications of these findings. tabs., figs.

  12. Reducing bacterial contamination in fuel ethanol fermentations by ozone treatment of uncooked corn mash. (United States)

    Rasmussen, Mary L; Koziel, Jacek A; Jane, Jay-lin; Pometto, Anthony L


    Ozonation of uncooked corn mash from the POET BPX process was investigated as a potential disinfection method for reducing bacterial contamination prior to ethanol fermentation. Corn mash (200 g) was prepared from POET ground corn and POET corn slurry and was ozonated in 250 mL polypropylene bottles. Lactic and acetic acid levels were monitored daily during the fermentation of ozonated, aerated, and nontreated corn mash samples to evaluate bacterial activity. Glycerol and ethanol contents of fermentation samples were checked daily to assess yeast activity. No yeast supplementation, no addition of other antimicrobial agents (such as antibiotics), and spiking with a common lactic acid bacterium found in corn ethanol plants, Lactobacillus plantarum, amplified the treatment effects. The laboratory-scale ozone dosages ranged from 26-188 mg/L, with very low estimated costs of $0.0008-0.006/gal ($0.21-1.6/m(3)) of ethanol. Ozonation was found to decrease the initial pH of ground corn mash samples, which could reduce the sulfuric acid required to adjust the pH prior to ethanol fermentation. Lactic and acetic acid levels tended to be lower for samples subjected to increasing ozone dosages, indicating less bacterial activity. The lower ozone dosages in the range applied achieved higher ethanol yields. Preliminary experiments on ozonating POET corn slurry at low ozone dosages were not as effective as using POET ground corn, possibly because corn slurry samples contained recycled antimicrobials from the backset. The data suggest additional dissolved and suspended organic materials from the backset consumed the ozone or shielded the bacteria.

  13. Optimization study of ethanolic fermentation from oil palm trunk, rubberwood and mixed hardwood hydrolysates using Saccharomyces cerevisiae. (United States)

    Chin, K L; H'ng, P S; Wong, L J; Tey, B T; Paridah, M T


    Ethanolic fermentation using Saccharomyces cerevisiae was carried out on three types of hydrolysates produced from lignocelulosic biomass which are commonly found in Malaysia such as oil palm trunk, rubberwood and mixed hardwood. The effect of fermentation temperature and pH of hydrolysate was evaluated to optimize the fermentation efficiency which defined as maximum ethanol yield in minimum fermentation time. The fermentation process using different temperature of 25 degrees Celsius, 30 degrees Celsius and 40 degrees Celsius were performed on the prepared fermentation medium adjusted to pH 4, pH 6 and pH 7, respectively. Results showed that the fermentation time was significantly reduced with the increase of temperature but an adverse reduction in ethanol yield was observed using temperature of 40 degrees Celsius. As the pH of hydrolysate became more acidic, the ethanol yield increased. Optimum fermentation efficiency for ethanolic fermentation of lignocellulosic hydrolysates using S. cerevisiae can be obtained using 33.2 degrees Celsius and pH 5.3.

  14. Enzymatic hydrolysis of market vegetable waste and subsequent ethanol fermentation-Kinetic evaluation

    Directory of Open Access Journals (Sweden)

    Chiranjeevi T


    Full Text Available Normal 0 false false false EN-US X-NONE X-NONE In this work, kinetic properties evaluation was made for bioethanol production from sugar hydrolysate of vegetable waste. The saccharified sugars were fermented by using Saccharomyces cerevisiae. The effect of various saccharification factors on sugars release were studied and observed that the optimized conditions contributed to 14.4 gL-1of fermentable sugars production. The produced sugars were subjected to batch fermentation by Saccharomyces cerevisiae at pH 4.5 and the kinetic parameters of fermentation were estimated by fitting the experimental data in modified logistic equations. The data revealed product (ethanol yield (YP/S of 0.39g/g of reducing sugars. Maximum specific growth rate (µmax, the yield of ethanol on biomass (YP/X and the yield of biomass on sugars utilization (YX/S were determined to be 0.18 h-1, 1.097 g/g and 0.313 g/g, respectively. The process yielded 4.13 gL-1 of ethanol by consumption of 10.6 gL-1 sugars with a volumetric production rate of 0.0861±0.002 gL-1 h-1.  

  15. Process of preparing ethanol by continuous fermentation of polysaccharide-containing materials

    Energy Technology Data Exchange (ETDEWEB)

    Ehnstroem, L.K.J.


    The invention concerns a process of preparing ethanol by continuous fermentation of polysaccharide - containing raw materials. Fermentation, hereby, occurs in one or several fermentors while dividing one stream of the fermentation liquid into a yeast-concentrate stream and a yeast-free stream and, if neccessary, a sludge stream. The yeast-concentrate stream is re-fed into the fermentor and at least part of the yeast-free stream is directed into a simple evaporator corresponding to one or several distilling stages where it is separated partially in an ethanol-enriched initial vapour stream supplying a facility to produce the desired ethanol quality, and partially in a liquid initial bottom stream re-fed at least in part into the fermentor. The characteristic feature of this new process is that a raw-material stream is fed into a closed circuit containing the fermentor and the evaporator, and that, in the evaporator, the raw-material stream is hydrolysed to a fermentable state. This hydrolysis is carried out most favourably by enzymes - preferably a gluco-amylase - at a temperature ranging from 35/sup 0/C to 75/sup 0/C.

  16. Ethanol production in fermentation of mixed sugars containing xylose (United States)

    Viitanen, Paul V.; Mc Cutchen, Carol M.; Li; Xu; Emptage, Mark; Caimi, Perry G.; Zhang, Min; Chou, Yat-Chen; Franden, Mary Ann


    Xylose-utilizing Z. mobilis strains were found to have improved ethanol production when grown in medium containing mixed sugars including xylose if sorbitol or mannitol was included in the medium. The effect was seen in concentrations of mixed sugars where no growth lag period occurs, as well as in higher sugars concentrations.

  17. Effect of flocculation on performance of arming yeast in direct ethanol fermentation

    Energy Technology Data Exchange (ETDEWEB)

    Khaw Teik Seong; Katakura, Yoshio; Ninomiya, Kazuaki; Shioya, Suteaki [Osaka Univ. (Japan). Dept. of Biotechnology; Bito, Yohei; Katahira, Satoshi; Kondo, Akihiko [Kobe Univ. (Japan). Dept. of Chemical Science and Engineering; Ueda, Mitsuyoshi [Kyoto Univ. (Japan). Div. of Applied Life Sciences


    In the direct ethanol fermentation of raw starch by arming yeast with {alpha}-amylase and glucoamylase, it is preferable to use a flocculent yeast because it can be recovered without centrifugation. Three types of arming yeast system, I (nonflocculent), II (mildly flocculent), and III (heavily flocculent), were constructed and their fermentation performances were compared. With an increase in the degree of flocculation, specific ethanol production rate for soluble starch decreased (0.19, 0.17, and 0.12 g g-dry-cell{sup -1} h{sup -1} for systems I, II, and III, respectively), but that for raw starch did not decrease as much as expected (0.06, 0.06, and 0.04 g g-dry-cell{sup -1} h{sup -1} for systems I, II and III, respectively). Microscopic observation revealed that many starch granules were captured in the yeast flocs in system III during the direct ethanol fermentation of raw starch. It was suggested that the capture of starch granules increases apparent substrate concentration for amylolytic enzymes in arming yeast cell flocs; thus, the specific ethanol production rate of system III was kept at a level comparable to those of the other systems. (orig.)

  18. Improvements in ethanol production from xylose by mating recombinant xylose-fermenting Saccharomyces cerevisiae strains. (United States)

    Kato, Hiroko; Suyama, Hiroaki; Yamada, Ryosuke; Hasunuma, Tomohisa; Kondo, Akihiko


    To improve the ability of recombinant Saccharomyces cerevisiae strains to utilize the hemicellulose components of lignocellulosic feedstocks, the efficiency of xylose conversion to ethanol needs to be increased. In the present study, xylose-fermenting, haploid, yeast cells of the opposite mating type were hybridized to produce a diploid strain harboring two sets of xylose-assimilating genes encoding xylose reductase, xylitol dehydrogenase, and xylulokinase. The hybrid strain MN8140XX showed a 1.3- and 1.9-fold improvement in ethanol production compared to its parent strains MT8-1X405 and NBRC1440X, respectively. The rate of xylose consumption and ethanol production was also improved by the hybridization. This study revealed that the resulting improvements in fermentation ability arose due to chromosome doubling as well as the increase in the copy number of xylose assimilation genes. Moreover, compared to the parent strain, the MN8140XX strain exhibited higher ethanol production under elevated temperatures (38 °C) and acidic conditions (pH 3.8). Thus, the simple hybridization technique facilitated an increase in the xylose fermentation activity.

  19. Cellulosic ethanol fermentation using Saccharomyces cerevisiae seeds cultured by pretreated corn stover material. (United States)

    Qureshi, Abdul Sattar; Zhang, Jian; Bao, Jie


    Utilization of lignocellulose materials to replace the pure glucose for preparation of the fermenting yeast seeds could reduce the cost of ethanol fermentation, because a large quantity of glucose is saved in the large-scale seed fermentor series. In this study, Saccharomyces cerevisiae DQ1 was cultured using the freshly pretreated corn stover material as the carbon source, and then the culture broth was used as the inoculation seeds after a series of seed transfer and inoculated into the ethanol production fermentor. The results show that the yeast cell growth and ethanol fermentation performance have essentially no difference when the yeast seeds were cultured by glucose, the corn stover hydrolysate liquid, and the pretreated corn stover solids as carbon sources, respectively. Approximately 22% of the yeast cell culture cost was saved, and the process flow sheet in industrial scale plants was simplified by using the pretreated corn stover for seed culture. The results provided a practical method for materials and operational cost reduction for cellulosic ethanol production.

  20. Characterization of very high gravity ethanol fermentation of corn mash. Effect of glucoamylase dosage, pre-saccharification and yeast strain

    DEFF Research Database (Denmark)

    Devantier, Rasmus; Pedersen, S; Olsson, Lisbeth


    specific growth rate was decreased. Ethanol production was not only growth related, as more than half of the total saccharides were consumed and more than half of the ethanol was produced during the stationary phase. Furthermore, a high stress tolerance of the applied yeast strain was found to be crucial...... for the outcome of the fermentation process, both with regard to residual saccharides and final ethanol concentration. The increased formation of cell mass when a well-suited strain was applied increased the final ethanol concentration, since a more complete fermentation was achieved....

  1. Parameter estimation for simultaneous saccharification and fermentation of food waste into ethanol using Matlab Simulink. (United States)

    Davis, Rebecca Anne


    The increase in waste disposal and energy costs has provided an incentive to convert carbohydrate-rich food waste streams into fuel. For example, dining halls and restaurants discard foods that require tipping fees for removal. An effective use of food waste may be the enzymatic hydrolysis of the waste to simple sugars and fermentation of the sugars to ethanol. As these wastes have complex compositions which may change day-to-day, experiments were carried out to test fermentability of two different types of food waste at 27 degrees C using Saccharomyces cerevisiae yeast (ATCC4124) and Genencor's STARGEN enzyme in batch simultaneous saccharification and fermentation (SSF) experiments. A mathematical model of SSF based on experimentally matched rate equations for enzyme hydrolysis and yeast fermentation was developed in Matlab Simulink. Using Simulink parameter estimation 1.1.3, parameters for hydrolysis and fermentation were estimated through modified Michaelis-Menten and Monod-type equations with the aim of predicting changes in the levels of ethanol and glycerol from different initial concentrations of glucose, fructose, maltose, and starch. The model predictions and experimental observations agree reasonably well for the two food waste streams and a third validation dataset. The approach of using Simulink as a dynamic visual model for SSF represents a simple method which can be applied to a variety of biological pathways and may be very useful for systems approaches in metabolic engineering in the future.

  2. Parameter Estimation for Simultaneous Saccharification and Fermentation of Food Waste Into Ethanol Using Matlab Simulink (United States)

    Davis, Rebecca Anne

    The increase in waste disposal and energy costs has provided an incentive to convert carbohydrate-rich food waste streams into fuel. For example, dining halls and restaurants discard foods that require tipping fees for removal. An effective use of food waste may be the enzymatic hydrolysis of the waste to simple sugars and fermentation of the sugars to ethanol. As these wastes have complex compositions which may change day-to-day, experiments were carried out to test fermentability of two different types of food waste at 27° C using Saccharomyces cerevisiae yeast (ATCC4124) and Genencor's STARGEN™ enzyme in batch simultaneous saccharification and fermentation (SSF) experiments. A mathematical model of SSF based on experimentally matched rate equations for enzyme hydrolysis and yeast fermentation was developed in Matlab Simulink®. Using Simulink® parameter estimation 1.1.3, parameters for hydrolysis and fermentation were estimated through modified Michaelis-Menten and Monod-type equations with the aim of predicting changes in the levels of ethanol and glycerol from different initial concentrations of glucose, fructose, maltose, and starch. The model predictions and experimental observations agree reasonably well for the two food waste streams and a third validation dataset. The approach of using Simulink® as a dynamic visual model for SSF represents a simple method which can be applied to a variety of biological pathways and may be very useful for systems approaches in metabolic engineering in the future.

  3. Spittlebug infestation in sugarcane affects ethanolic fermentation A infestação de cigarrinha-das-raízes em cana-de-açúcar afeta a fermentação etanólica

    Directory of Open Access Journals (Sweden)

    Gisele Cristina Ravaneli


    Full Text Available The spittlebug (Mahanarva fimbriolata has become a key pest of the sugarcane crop in Brazil with the increase of green-cane harvesting, causing stalk yield and cane quality losses. This research was undertaken to evaluate the effects of the spittlebug (Mahanarva fimbriolata on cane quality and juice fermentation. The experiment was arranged in a completely randomized 5 × 2 factorial design, with five spittlebug infestation levels (0-0.5; 0.6-2.5; 2.6-5; 5.1-8; 8.1-12.5 nymphs m-1, controlled or not with thiamethoxam (0.2 kg of active ingredient ha-1. To conduct fermentation, Saccharomyces cerevisiae (fresh and pressed baker's yeast was inoculated to musts at a concentration of 30 g L-1. Microbiological analyses were performed at the beginning, middle and end of the fermentation process. The alcohol content and total residual reducing sugars were measured in the wine. Spittlebug attack influenced negatively sugarcane quality, yeast cell and bud viability, and wine alcohol content. Insecticide application resulted in higher cane quality and cell and bud viabilities, resulting in increased fermentation yield.A cigarrinha-das-raízes (Mahanarva fimbriolata tornou-se praga-chave na cultura da cana-de-açúcar com a expansão das áreas de colheita sem queima, comprometendo a produtividade e a qualidade da matéria-prima e consequentemente o processamento industrial. Essa pesquisa objetivou avaliar os efeitos da cigarrinha-das-raízes (Mahanarva fimbriolata sobre a qualidade da cana-de-açúcar e a fermentação do caldo. O delineamento experimental utilizado foi inteiramente casualizado, em esquema fatorial 5 × 2, sendo cinco níveis iniciais de infestação da cigarrinha-das-raízes (0-0,5; 0,6-2,5; 2,6-5; 5,1-8; 8,1-12,5 ninfas m-1, controlados ou não com o inseticida thiamethoxam (0,2 kg de ingrediente ativo ha-1. Para a fermentação alcoólica, o fermento prensado Saccharomyces cerevisiae foi inoculado aos mostos na concentração de 30 g L-1

  4. Tyrosinase Inhibitory Effect and Antioxidative Activities of Fermented and Ethanol Extracts of Rhodiola rosea and Lonicera japonica

    Directory of Open Access Journals (Sweden)

    Yuh-Shuen Chen


    Full Text Available This is the first study to investigate the biological activities of fermented extracts of Rhodiola rosea L. (Crassulaceae and Lonicera japonica Thunb. (Caprifoliaceae. Alcaligenes piechaudii CC-ESB2 fermented and ethanol extracts of Rhodiola rosea and Lonicera japonica were prepared and the antioxidative activities of different concentrations of samples were evaluated using in vitro antioxidative assays. Tyrosinase inhibition was determined by using the dopachrome method with L-DOPA as substrate. The results demonstrated that inhibitory effects (ED50 values on mushroom tyrosinase of fermented Rhodiola rosea, fermented Lonicera japonica, ethanol extract of Lonicera japonica, and ethanol extract of Rhodiola rosea were 0.78, 4.07, 6.93, and >10 mg/ml, respectively. The DPPH scavenging effects of fermented Rhodiola rosea (ED50 = 0.073 mg/ml and fermented Lonicera japonica (ED50 = 0.207 mg/ml were stronger than effects of their respective ethanol extracts. Furthermore, the scavenging effect increases with the presence of high content of total phenol. However, the superoxide scavenging effects of fermented Rhodiola rosea was less than effects of fermented Lonicera japonica. The results indicated that fermentation of Rhodiola rosea and Lonicera japonica can be considered as an effective biochemical process for application in food, drug, and cosmetics.

  5. Tracing carbon monoxide uptake by Clostridium ljungdahlii during ethanol fermentation using (13)C-enrichment technique. (United States)

    Yun, Seok-In; Gang, Seong-Joo; Ro, Hee-Myong; Lee, Min-Jin; Choi, Woo-Jung; Hong, Seong-Gu; Kang, Kwon-Kyoo


    Conversion of synthesis gas (CO and H2) to ethanol can be an alternative, promising technology to produce biofuels from renewable biomass. To distinguish microbial utilization of carbon source between fructose and synthesis gas CO and to evaluate biological production of ethanol from CO, we adopted the (13)C-enrichment of the CO substrate and hypothesized that the residual increase in δ(13)C of the cell biomass would reflect the increased contribution of (13)C-enriched CO. Addition of synthesis gas to live culture medium for ethanol fermentation by Clostridum ljungdahlii increased the microbial growth and ethanol production. Despite the high (13)C-enrichment in CO (99 atom % (13)C), however, microbial δ(13)C increased relatively small compared to the microbial growth. The uptake efficiency of CO estimated using the isotope mass balance equation was also very low: 0.0014 % for the low CO and 0.0016 % for the high CO treatment. Furthermore, the fast production of ethanol in the early stage indicated that the presence of sugar in fermentation medium would limit the utilization of CO as a carbon source by C. ljungdahlii.

  6. Variation of the ethanol yield during very rapid batch fermentation of sugar-cane black strap molasses

    Energy Technology Data Exchange (ETDEWEB)

    Borzani, W.; Jurkiewicz, C.H. [Instituto Maua de Tecnologia, Sao Caetano do Sul, SP (Brazil)


    During rapid ethanol fermentation (2-3 h) of sugar-cane black strap molasses, a significant increase in the ethanol yield was frequently observed as fermentation proceeded, eventually leading to yields higher than the theoretical value when the end of the process was approached. In order to explain the above facts, three assumptions were examined: temporary ethanol accumulation within the yeast cells; variation of the dry matter content and/or of the microorganism density during the fermentation; transformation of sugars into undetectable extra-cellular fermentable compounds at the initial stages of the process. Based on on the experimental results presented here, the third of the above assumptions seems to explain the observed increase in the ethanol yield. (author) 16 refs., 6 figs., 4 tabs.

  7. Influence of the rate of ethanol production and accumulation on the viability of Saccharomyces cerevisiae in "rapid fermentation". (United States)

    Nagodawithana, T W; Steinkraus, K H


    Whereas "rapid fermentation" of diluted clover honey (25 degrees Brix) fortified with yeast nutrients using 8 X 10(8) brewers' yeast cells per ml resulted in an ethanol content of 9.5% (wt/vol; 12% vol/vol) in 3 h at 30 C, death rate of the yeast cells during this period was essentially logarithmic. Whereas 6 h was required to reach the same ethanol content at 15 C, the yeast cells retained their viability. Using a lower cell population (6 X 10(7) cells/ml), a level at which the fermentation was no longer "rapid," the yeast cells also retained their viability at 30 C. Ethanol added to the medium was much less lethal than the same or less quantities of ethanol produced by the cell in "rapid fermentation." It was considered possible that ethanol was produced so rapidly at 30 C that it could not diffuse out of the cell as rapidly as it was formed. The hypothesis was postulated that ethanol accumulating in the cell was contributing to the high death rate at 30 C. It was found that the intracellular ethanol concentration reached a level of approximately 2 X 10(11) ethanol molecules/cell in the first 30 min of fermentation at 30 C. At 15 C, with the same cell count, intracellular ethanol concentration reached a level of approximately 4 X 10(10) ethanol molecules/cell and viability remained high. Also, at 30 C with a lower cell population (6 X 10(7) cells/ml), under which conditions fermentation was no longer "rapid," intracellular ethanol concentration reached a similar level (4 X 10(10) molecules ethanol/cell) and the cells retained their viability. Alcohol dehydrogenase (ADH) lost its activity in brewers' yeast under conditions of "rapid fermentation" at 30 C but retained its activity in cells under similar conditions at 15 C. ADH activity was also retained in fermentations at 30 C with cell populations of 6 X 10(7)/ml. It would appear that an intracellular level of about 5 X 10(10) ethanol molecules/cell is normal and that this level does not damage either cell

  8. Effects of ethanol, octanoic and decanoic acids of fermentation and the passive influx of protons through the plasma membrane of Saccharomyces cerevisiae

    Energy Technology Data Exchange (ETDEWEB)

    Stevens, S. (Nietvoorbij Inst. of Viticulture and Oenology, Stellenbosch (South Africa)); Hofmeyr, J.H.S. (Dept. of Biochemistry and Inst. of Biotechnology, Stellenbosch Univ. (South Africa))


    Ethanol, octanoic and decanoic acids are known toxic products of alcoholic fermentation and inhibit yeast functions such as growth and fermentation. pH-stat measurements showed that, in a concentration range up to 20 mg/l, octanoic and decaonoic acids increase the rate of passive H[sup +] influx across the plama membrane of Saccharomyces cerevisiae IGC 3507. Decanoic acid was more active than octanoic acid, which agrees with its higher liposolubility. The fatty acids probably act as H[sup +] carriers, since the magnitude of the effect depended on pH and correlated with the concentration of protonated fatty acids. Esterification of the fatty acids partially abolished the enhancing effect on passive H[sup +] influx. Passive H[sup +] influx showed saturation kinetics with half-maximal activity at 6.6 [mu]M H[sup +] (pH 5.2). Contrary to previous findings, ethanol inhibited H[sup +] influx exponentially up to a concentration of 8% (v/v). At higher concentrations, ethanol reactivated H[sup +] influx; the original rate of H[sup +] uptake was reached at 14% (v/v) ethanol. In the same concentration ranges that affected passive H[sup +] influx, ethanol, octanoic and decanoic acids inhibited the fermentation rate. This inhibitory effect of the fatty acids on fermentation rate depended on liposolubility, pH, and esterification in the same way as that found for their effect on passive H[sup +] influx. Inhibition of fermentation by octanoic and decanoic acids could therefore result from their effect on the rate of passive H[sup +] influx. (orig.).

  9. Isolation, identification and optimization of ethanol producing bacteria from Saccharomyces-based fermentation process of alcohol industries in Iran


    Hoda Ebrahimi; Mojtaba Mohseni


    Introduction: Due to the vast growth of world population, consumption of a lot of energy, limited energy supply and rising prices of fuel oil in the future, other alternative energy source is essential. Ethanol is renewable and a safe fuel and it is mainly based on microbial fermentation. The purpose of this study was isolation of high ethanol producing bacteria from the fermentation process of alcohol industries and optimization of growth conditions to be introduced to the industries. Materi...

  10. Monitoring of monosaccharides, oligosaccharides, ethanol and glycerol during wort fermentation by biosensors, HPLC and spectrophotometry. (United States)

    Monošík, Rastislav; Magdolen, Peter; Stredanský, Miroslav; Šturdík, Ernest


    The aim of the present study was to analyze sugar levels (namely maltose, maltotriose, glucose and fructose) and alcohols (ethanol and glycerol) during the fermentation process in wort samples by amperometric enzymatic biosensors developed by our research group for industrial application, HPLC and spectrophotometry, and to compare the suitability of the presented methods for determination of individual analytes. We can conclude that for the specific monitoring of maltose or maltotriose only the HPLC method was suitable. On the other hand, biosensors and spectrophotometry reflected a decrease in total sugar concentration better and were able to detect both glucose and fructose in the later stages of fermentation, while HPLC was not. This can be attributed to the low detection limits and good sensitivity of the proposed methods. For the ethanol and glycerol analysis all methods proved to be suitable. However, concerning the cost expenses and time analysis, biosensors represented the best option.

  11. Continuous ethanol fermentation of lactose by a recombinant flocculating Saccharomyces cerevisiae strain

    Energy Technology Data Exchange (ETDEWEB)

    Domingues, L.; Dantas, M.M.; Lima, N.; Teixeira, J.A. [Universidade do Minho, Braga (Portugal). Centro do Engeharia Biologica-IBQF


    Alcohol fermentation of lactose was investigated using a recombinant flocculating Saccharomyces cetevisiae, expressing the LAC4 (coding the {beta}-galactosidase) and LAC12 (coding for lactose permease) genes of Kluyveromyces marxianus. Data on yeast fermentation and growth on a medium containing lactose as the sole carbon source are presented. In the range of studied lactose concentrations, total lactose consumption was observed with a conversion yield of ethanol close to the expected theoretical value. For the continuously operating bioreactor, an ethanol productivity of 11 g L{sup {minus}1} h{sup {minus}1} (corresponding to a feed lactose concentration of 50 g L{sup {minus}1} and a dilution rate of 0.55 h{sup {minus}1}) was obtained, which is 7 times larger than the continuous conventional systems. The system stability was confirmed by keeping it in operation for 6 months.

  12. Novel strategy to improve vanillin tolerance and ethanol fermentation performances of Saccharomycere cerevisiae strains. (United States)

    Zheng, Dao-Qiong; Jin, Xin-Na; Zhang, Ke; Fang, Ya-Hong; Wu, Xue-Chang


    The aim of this work was to develop a novel strategy for improving the vanillin tolerance and ethanol fermentation performances of Saccharomyces cerevisiae strains. Isogeneic diploid, triploid, and tetraploid S. cerevisiae strains were generated by genome duplication of haploid strain CEN.PK2-1C. Ploidy increments improved vanillin tolerance and diminished proliferation capability. Antimitotic drug methyl benzimidazol-2-ylcarbamate (MBC) was used to introduce chromosomal aberrations into the tetraploid S. cerevisiae strain. Interestingly, aneuploid mutants with DNA contents between triploid and tetraploid were more resistant to vanillin and showed faster ethanol fermentation rates than all euploid strains. The physiological characteristics of these mutants suggest that higher bioconversion capacities of vanillin and ergosterol contents might contribute to improved vanillin tolerance. This study demonstrates that genome duplication and MBC treatment is a powerful strategy to improve the vanillin tolerance of yeast strains.

  13. Techno-economic analysis of corn stover fungal fermentation to ethanol

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, Pimphan A.; Tews, Iva J.; Magnuson, Jon K.; Karagiosis, Sue A.; Jones, Susanne B.


    This techno-economic analysis assesses the process economics of ethanol production from lignocellulosic feedstock by fungi to identify promising opportunities, and the research needed to achieve them. Based on literature derived data, four different ethanologen strains are considered in this study: native and recombinant Saccharomyces cerevisiae, the natural pentose-fermenting yeast, Pichia stipitis and the filamentous fungus Fusarium oxysporum. In addition, filamentous fungi are applied in multi-organism and consolidated process configurations. Organism performance and technology readiness are categorized as near-term (<5 years), mid-term (5-10 years), and long-term (>10 years) process deployment. The results of the analysis suggest that the opportunity for fungal fermentation exists for lignocellulosic ethanol production.

  14. Acceleration of the rate of ethanol fermentation by addition of nitrogen in high tannin grain sorghum

    Energy Technology Data Exchange (ETDEWEB)

    Mullins, J.T.; NeSmith, C.C.


    In this communication, the authors show that accelerated rates of ethanol production, comparable to sorghum varieties containing low levels of tannins and to corn, can occur without the removal of the tannins. The basis of the inhibition appears to be a lack of sufficient nitrogen in the mash for protein synthesis required to support an accelerated fermentative metabolism in Saccharomyces. No inhibition of the enzymes used for starch hydrolysis was found.


    Saccharomyces cerevisiae 424A (LNH-ST) strain was used for fermentation of glucose and xylose. Growth kinetics and ethanol productivity were calculated for batch fermentation on media containing different combinations of glucose and xylose to give a final sugar concentra...

  16. Efficiency of Blenke cascade system for continuous bio-ethanol fermentation. (United States)

    Ntihuga, Jean Nepomuscene; Senn, Thomas; Gschwind, Peter; Kohlus, Reinhard


    A gas lift-system with inserts (so-called Blenke cascade system) for continuous bio-ethanol fermentation was constructed. Gas introduced at the bottom of the column created toroidal vortices in the fluid cells between inserts, enhancing mixing and improving residence time behavior without stirring equipment being necessary. The parameters mash type, start-up strategy, yeast-recycle model and yeast separation were studied concerning the efficiency of the ethanol production. The best results obtained were for a filtered mash, a double saccharification principle (DSP), a batch start-up strategy, an activation-recycle model and a lamella settler connected in series with a small conventional gravitational settler for yeast cells separation. Using this system, the fermentation residence time was τ=4-5.5h, depending on substrate type. Eighty five percent of the yeast cells could be separated. High volumetric ethanol productivity (Q(p)=20.43g/Lh) and yield E(y)=98% were achieved. Continuous fermentation, yeast recycling and sedimentation were contamination-free processes.

  17. [Production of ethanol and isoflavones from steam-pretreated Radix Puerariae by solid state fermentation]. (United States)

    Fu, Xiaoguo; Chen, Hongzhang; Wang, Weidong


    The gelatinization process of the starch is replaced by unpolluted steam-pretreatment on the base of the Radix Puerariae rich in fiber and isoflavones. The production of ethanol and isoflavones by simultaneous saccharification and solid state fermentation (SSF) of steam-pretreatment Radix Puerariae is presented. The optimal technological conditions were obtained: Radix Puerariae being steam-pretreated at a saturated vapor pressure of 0.8 MPa for 3.5 min, glucoamylase(65 u/g), cellulase(1.5 u/g), 0.1%(NH4)2SO4, 0.1%KH2PO4 and activated yeasts being added in, and fermentation at 35-37 degrees C for 60 h. Under these conditions, the yield of ethanol and isoflavones from 100 g Radix Pureriae (dry basis) were 27.47 g and 4.43 g, respectively, the starch utilization rate was 95%. In comparison with the traditional fermentation technology, the simultaneous saccharification and SSF of steam-pretreatment Radix Puerariae is clean and energy-saving. It provides new way of the production of ethanol from the non-food starch material, and worthwhile to be explored and implemented in industry.

  18. Acid-catalyzed steam pretreatment of lodgepole pine and subsequent enzymatic hydrolysis and fermentation to ethanol. (United States)

    Ewanick, Shannon M; Bura, Renata; Saddler, John N


    Utilization of ethanol produced from biomass has the potential to offset the use of gasoline and reduce CO(2) emissions. This could reduce the effects of global warming, one of which is the current outbreak of epidemic proportions of the mountain pine beetle (MPB) in British Columbia (BC), Canada. The result of this is increasing volumes of dead lodgepole pine with increasingly limited commercial uses. Bioconversion of lodgepole pine to ethanol using SO(2)-catalyzed steam explosion was investigated. The optimum pretreatment condition for this feedstock was determined to be 200 degrees C, 5 min, and 4% SO(2) (w/w). Simultaneous saccharification and fermentation (SSF) of this material provided an overall ethanol yield of 77% of the theoretical yield from raw material based on starting glucan, mannan, and galactan, which corresponds to 244 g ethanol/kg raw material within 30 h. Three conditions representing low (L), medium (M), and high (H) severity were also applied to healthy lodgepole pine. Although the M severity conditions of 200 degrees C, 5 min, and 4% SO(2) were sufficiently robust to pretreat healthy wood, the substrate produced from beetle-killed (BK) wood provided consistently higher ethanol yields after SSF than the other substrates tested. BK lodgepole pine appears to be an excellent candidate for efficient and productive bioconversion to ethanol.

  19. Fermentative production of ethanol from syngas using novel moderately alkaliphilic strains of Alkalibaculum bacchi. (United States)

    Liu, Kan; Atiyeh, Hasan K; Tanner, Ralph S; Wilkins, Mark R; Huhnke, Raymond L


    Ethanol production from syngas using three moderately alkaliphilic strains of a novel genus and species Alkalibaculum bacchi CP11(T), CP13 and CP15 was investigated in 250 ml bottle fermentations containing 100ml of yeast extract medium at 37 °C and pH 8.0. Two commercial syngas mixtures (Syngas I: 20% CO, 15% CO(2), 5% H(2), 60% N(2)) and (Syngas II: 40% CO, 30% CO(2), 30% H(2)) were used. Syngas I and Syngas II represent gasified biomass and coal, respectively. The maximum ethanol concentration (1.7 g l(-1)) and yield from CO (76%) were obtained with strain CP15 and Syngas II after 360 h. CP15 produced over twofold more ethanol with Syngas I compared to strains CP11(T) and CP13. In addition, CP15 produced 18% and 71% more ethanol using Syngas II compared to strains CP11(T) and CP13, respectively. These results show that CP15 is the most promising for ethanol production because of its higher growth and ethanol production rates and yield compared to CP11(T) and CP13.

  20. Hominids adapted to metabolize ethanol long before human-directed fermentation (United States)

    Carrigan, Matthew A.; Uryasev, Oleg; Frye, Carole B.; Eckman, Blair L.; Myers, Candace R.; Hurley, Thomas D.; Benner, Steven A.


    Paleogenetics is an emerging field that resurrects ancestral proteins from now-extinct organisms to test, in the laboratory, models of protein function based on natural history and Darwinian evolution. Here, we resurrect digestive alcohol dehydrogenases (ADH4) from our primate ancestors to explore the history of primate–ethanol interactions. The evolving catalytic properties of these resurrected enzymes show that our ape ancestors gained a digestive dehydrogenase enzyme capable of metabolizing ethanol near the time that they began using the forest floor, about 10 million y ago. The ADH4 enzyme in our more ancient and arboreal ancestors did not efficiently oxidize ethanol. This change suggests that exposure to dietary sources of ethanol increased in hominids during the early stages of our adaptation to a terrestrial lifestyle. Because fruit collected from the forest floor is expected to contain higher concentrations of fermenting yeast and ethanol than similar fruits hanging on trees, this transition may also be the first time our ancestors were exposed to (and adapted to) substantial amounts of dietary ethanol. PMID:25453080

  1. Fungal protein and ethanol from lignocelluloses using Rhizopus pellets under simultaneous saccharification, filtration and fermentation (SSFF

    Directory of Open Access Journals (Sweden)

    Somayeh FazeliNejad


    Full Text Available The economic viability of the 2nd generation bioethanol production process cannot rely on a single product but on a biorefinery built around it. In this work, ethanol and fungal biomass (animal feed were produced from acid-pretreated wheat straw slurry under an innovative simultaneous saccharification, fermentation, and filtration (SSFF strategy. A membrane unit separated the solids from the liquid and the latter was converted to biomass or to both biomass and ethanol in the fermentation reactor containing Rhizopus sp. pellets. Biomass yields of up to 0.34 g/g based on the consumed monomeric sugars and acetic acid were achieved. A surplus of glucose in the feed resulted in ethanol production and reduced the biomass yield, whereas limiting glucose concentrations resulted in higher consumption of xylose and acetic acid. The specific growth rate, in the range of 0.013-0.015/h, did not appear to be influenced by the composition of the carbon source. Under anaerobic conditions, an ethanol yield of 0.40 g/g was obtained. The present strategy benefits from the easier separation of the biomass from the medium and the fungus ability to assimilate carbon residuals in comparison with when yeast is used. More specifically, it allows in-situ separation of insoluble solids leading to the production of pure fungal biomass as a value-added product.

  2. Effects of galactose adaptation in yeast for ethanol fermentation from red seaweed, Gracilaria verrucosa. (United States)

    Ra, Chae Hun; Kim, Yeong Jin; Lee, Sang Yoon; Jeong, Gwi-Taek; Kim, Sung-Koo


    A total monosaccharide concentration of 39.6 g/L, representing 74.0 % conversion of 53.5 g/L total carbohydrate from 80 g dw/L (8 % w/v) Gracilaria verrucosa slurry, was obtained by thermal acid hydrolysis and enzymatic saccharification. G. verrucosa hydrolysate was used as a substrate for ethanol production by 'separate hydrolysis and fermentation' (SHF). The ethanol production and yield (Y EtOH) from Saccharomyces cerevisiae KCCM 1129 with and without adaptation to high galactose concentrations were 18.3 g/L with Y EtOH of 0.46 and 13.4 g/L with Y EtOH of 0.34, respectively. Relationship between galactose adaptation effects and mRNA transcriptional levels were evaluated with GAL gene family, regulator genes of the GAL genetic switch and repressor genes in non-adapted and adapted S. cerevisiae. The development of galactose adaptation for ethanol fermentation of G. verrucosa hydrolysates allowed us to enhance the overall ethanol yields and obtain a comprehensive understanding of the gene expression levels and metabolic pathways involved.

  3. Starmerella bacillaris and Saccharomyces cerevisiae mixed fermentations to reduce ethanol content in wine. (United States)

    Englezos, Vasileios; Rantsiou, Kalliopi; Cravero, Francesco; Torchio, Fabrizio; Ortiz-Julien, Anne; Gerbi, Vincenzo; Rolle, Luca; Cocolin, Luca


    Decreasing the ethanol content in wine is a current challenge, mainly due to the global climate change and to the consumer preference for wines from grapes with increased maturity. In this study, a central composite design (CCD) and response surface methodology (RSM) approach was used to investigate the potential application of Starmerella bacillaris (synonym Candida zemplinina) in combination with Saccharomyces cerevisiae, in mixed (co-inoculated and sequential) cultures, to understand better the mechanism of co-habitation and achieve the objective of reducing the ethanol in wines. Laboratory scale fermentations demonstrated a decrease up to 0.7 % (v/v) of ethanol and an increase of about 4.2 g/L of glycerol when S. cerevisiae was inoculated with a delay of 48 h with respect to the inoculation of S. bacillaris. Pilot-scale fermentations, carried out in winemaking conditions, confirmed the laboratory results. This study demonstrates that the combination of strains and inoculation protocol could help to reduce the ethanol content in wines.

  4. Improving ethanol fermentation performance of Saccharomyces cerevisiae in very high-gravity fermentation through chemical mutagenesis and meiotic recombination

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jing-Jing; Ding, Wen-Tao; Zhang, Guo-Chang; Wang, Jing-Yu [Tianjin Univ. (China). Dept. of Biochemical Engineering


    Genome shuffling is an efficient way to improve complex phenotypes under the control of multiple genes. For the improvement of strain's performance in very high-gravity (VHG) fermentation, we developed a new method of genome shuffling. A diploid ste2/ste2 strain was subjected to EMS (ethyl methanesulfonate) mutagenesis followed by meiotic recombination-mediated genome shuffling. The resulting haploid progenies were intrapopulation sterile and therefore haploid recombinant cells with improved phenotypes were directly selected under selection condition. In VHG fermentation, strain WS1D and WS5D obtained by this approach exhibited remarkably enhanced tolerance to ethanol and osmolarity, increased metabolic rate, and 15.12% and 15.59% increased ethanol yield compared to the starting strain W303D, respectively. These results verified the feasibility of the strain improvement strategy and suggested that it is a powerful and high throughput method for development of Saccharomyces cerevisiae strains with desired phenotypes that is complex and cannot be addressed with rational approaches. (orig.)

  5. High solid simultaneous saccharification and fermentation of wet oxidized corn stover to ethanol

    DEFF Research Database (Denmark)

    Varga, E.; Klinke, H.B.; Reczey, K.


    In this study ethanol was produced from corn stover pretreated by alkaline and acidic wet oxidation (WO) (195 degreesC, 15 min, 12 bar oxygen) followed by nonisothermal simultaneous saccharification and fermentation (SSF). In the first step of the SSF, small amounts of cellulases were added at 50....../L) were present in the hemicellulose rich hydrolyzate at subinhibitory levels, thus no detoxification was needed prior to SSF of the whole slurry. Based on the cellulose available in the WO corn stover 83% of the theoretical ethanol yield was obtained under optimized SSF conditions. This was achieved...... with a substrate concentration of 12% dry matter (DM) acidic WO corn stover at 30 FPU/g DM (43.5 FPU/g cellulose) enzyme loading. Even with 20 and 15 FPU/g DM (corresponding to 29 and 22 FPU/g cellulose) enzyme loading, ethanol yields of 76 and 73%, respectively, were obtained. After 120 h of SSF the highest...

  6. Separate hydrolysis and co-fermentation for improved xylose utilization in integrated ethanol production from wheat meal and wheat straw

    Directory of Open Access Journals (Sweden)

    Erdei Borbála


    Full Text Available Abstract Background The commercialization of second-generation bioethanol has not been realized due to several factors, including poor biomass utilization and high production cost. It is generally accepted that the most important parameters in reducing the production cost are the ethanol yield and the ethanol concentration in the fermentation broth. Agricultural residues contain large amounts of hemicellulose, and the utilization of xylose is thus a plausible way to improve the concentration and yield of ethanol during fermentation. Most naturally occurring ethanol-fermenting microorganisms do not utilize xylose, but a genetically modified yeast strain, TMB3400, has the ability to co-ferment glucose and xylose. However, the xylose uptake rate is only enhanced when the glucose concentration is low. Results Separate hydrolysis and co-fermentation of steam-pretreated wheat straw (SPWS combined with wheat-starch hydrolysate feed was performed in two separate processes. The average yield of ethanol and the xylose consumption reached 86% and 69%, respectively, when the hydrolysate of the enzymatically hydrolyzed (18.5% WIS unwashed SPWS solid fraction and wheat-starch hydrolysate were fed to the fermentor after 1 h of fermentation of the SPWS liquid fraction. In the other configuration, fermentation of the SPWS hydrolysate (7.0% WIS, resulted in an average ethanol yield of 93% from fermentation based on glucose and xylose and complete xylose consumption when wheat-starch hydrolysate was included in the feed. Increased initial cell density in the fermentation (from 5 to 20 g/L did not increase the ethanol yield, but improved and accelerated xylose consumption in both cases. Conclusions Higher ethanol yield has been achieved in co-fermentation of xylose and glucose in SPWS hydrolysate when wheat-starch hydrolysate was used as feed, then in co-fermentation of the liquid fraction of SPWS fed with the mixed hydrolysates. Integration of first-generation and

  7. Evaluation of continuous ethanol fermentation of dilute-acid corn stover hydrolysate using thermophilic anaerobic bacterium Thermoanaerobacter BG1L1

    DEFF Research Database (Denmark)

    Georgieva, Tania I.; Ahring, Birgitte Kiær


    Dilute sulfuric acid pretreated corn stover is potential feedstock of industrial interest for second generation fuel ethanol production. However, the toxicity of corn stover hydrolysate (PCS) has been a challenge for fermentation by recombinant xylose fermenting organisms. In this work...

  8. Converting Chemical Oxygen Demand (COD) of Cellulosic Ethanol Fermentation Wastewater into Microbial Lipid by Oleaginous Yeast Trichosporon cutaneum. (United States)

    Wang, Juan; Hu, Mingshan; Zhang, Huizhan; Bao, Jie


    Cellulosic ethanol fermentation wastewater is the stillage stream of distillation column of cellulosic ethanol fermentation broth with high chemical oxygen demand (COD). The COD is required to reduce before the wastewater is released or recycled. Without any pretreatment nor external nutrients, the cellulosic ethanol fermentation wastewater bioconversion by Trichosporon cutaneum ACCC 20271 was carried out for the first time. The major components of the wastewater including glucose, xylose, acetic acid, ethanol, and partial of phenolic compounds could be utilized by T. cutaneum ACCC 20271. In a 3-L bioreactor, 2.16 g/L of microbial lipid accumulated with 55.05% of COD reduced after a 5-day culture of T. cutaneum ACCC 20271 in the wastewater. The fatty acid composition of the derived microbial lipid was similar with vegetable oil, in which it could be used as biodiesel production feedstock. This study will both solve the environmental problem and offer low-cost lipid feedstock for biodiesel production.

  9. Industrial symbiosis: corn ethanol fermentation, hydrothermal carbonization, and anaerobic digestion. (United States)

    Wood, Brandon M; Jader, Lindsey R; Schendel, Frederick J; Hahn, Nicholas J; Valentas, Kenneth J; McNamara, Patrick J; Novak, Paige M; Heilmann, Steven M


    The production of dry-grind corn ethanol results in the generation of intermediate products, thin and whole stillage, which require energy-intensive downstream processing for conversion into commercial animal feed products. Hydrothermal carbonization of thin and whole stillage coupled with anaerobic digestion was investigated as alternative processing methods that could benefit the industry. By substantially eliminating evaporation of water, reductions in downstream energy consumption from 65% to 73% were achieved while generating hydrochar, fatty acids, treated process water, and biogas co-products providing new opportunities for the industry. Processing whole stillage in this manner produced the four co-products, eliminated centrifugation and evaporation, and substantially reduced drying. With thin stillage, all four co-products were again produced, as well as a high quality animal feed. Anaerobic digestion of the aqueous product stream from the hydrothermal carbonization of thin stillage reduced chemical oxygen demand (COD) by more than 90% and converted 83% of the initial COD to methane. Internal use of this biogas could entirely fuel the HTC process and reduce overall natural gas usage.

  10. Characterization of very high gravity ethanol fermentation of corn mash. Effect of glucoamylase dosage, pre-saccharification and yeast strain

    Energy Technology Data Exchange (ETDEWEB)

    Devantier, R. [Starch, Applied Discovery, Research and Development, Novozymes A/S, Bagsvaerd (Denmark); Center for Microbial Biotechnology, BioCentrum-DTU, Technical Univ. of Denmark, Kgs Lyngby (Denmark); Pedersen, S. [Starch, Applied Discovery, Research and Development, Novozymes A/S, Bagsvaerd (Denmark); Olsson, L. [Center for Microbial Biotechnology, BioCentrum-DTU, Technical Univ. of Denmark, Kgs Lyngby (Denmark)


    Ethanol was produced from very high gravity mashes of dry milled corn (35% w/w total dry matter) under simultaneous saccharification and fermentation conditions. The effects of glucoamylase dosage, pre-saccharification and Saccharomyces cerevisiae strain on the growth characteristics such as the ethanol yield and volumetric and specific productivity were determined. It was shown that higher glucoamylase doses and/or pre-saccharification accelerated the simultaneous saccharification and fermentation process and increased the final ethanol concentration from 106 to 126 g/kg although the maximal specific growth rate was decreased. Ethanol production was not only growth related, as more than half of the total saccharides were consumed and more than half of the ethanol was produced during the stationary phase. Furthermore, a high stress tolerance of the applied yeast strain was found to be crucial for the outcome of the fermentation process, both with regard to residual saccharides and final ethanol concentration. The increased formation of cell mass when a well-suited strain was applied increased the final ethanol concentration, since a more complete fermentation was achieved. (orig.)

  11. Anaerobic bio-hydrogen production from ethanol fermentation: the role of pH. (United States)

    Hwang, Moon H; Jang, Nam J; Hyun, Seung H; Kim, In S


    Hydrogen was produced by an ethanol-acetate fermentation at pH of 5.0 +/- 0.2 and HRT of 3 days. The yield of hydrogen was 100-200 ml g Glu(-1) with a hydrogen content of 25-40%. This fluctuation in the hydrogen yield was attributed to the formation of propionate and the activity of hydrogen utilizing methanogens. The change in the operational pH for the inhibition of this methanogenic activity induced a change in the main fermentation pathway. In this study, the main products were butyrate, ethanol and propionate, in the pH ranges 4.0-4.5, 4.5-5.0 and 5.0-6.0, respectively. However, the activity of all the microorganisms was inhibited below pH 4.0. Therefore, pH 4.0 was regarded as the operational limit for the anaerobic bio-hydrogen production process. These results indicate that the pH plays an important role in determining the type of anaerobic fermentation pathway in anaerobic bio-hydrogen processes.

  12. Achieving ethanol-type fermentation for hydrogen production in a granular sludge system by aeration. (United States)

    Zhang, Song; Liu, Min; Chen, Ying; Pan, Yu-Ting


    To investigate the effects of aeration on hydrogen-producing granular system, experiments were performed in two laboratory-scale anaerobic internal circulation hydrogen production (AICHP) reactors. The preliminary experiment of Reactor 1 showed that direct aeration was beneficial to enhancing hydrogen production. After the direct aeration was implied in Reactor 2, hydrogen production rate (HPR) and hydrogen content were increased by 100% and 60%, respectively. In addition, mixed-acid fermentation was transformed into typical ethanol-type fermentation (ETF). Illumina MiSeq sequencing shows that the direct aeration did not change the species of hydrogen-producing bacteria but altered their abundance. Hydrogen-producing bacteria and ethanol-type fermentative bacteria were increased by 24.5% and 146.3%, respectively. Ethanoligenens sp. sharply increased by 162.2% and turned into predominant bacteria in the system. These findings indicated that appropriate direct aeration might be a novel and promising way to obtain ETF and enhance hydrogen production in practical use.

  13. Acid hydrolysis of Curcuma longa residue for ethanol and lactic acid fermentation. (United States)

    Nguyen, Cuong Mai; Nguyen, Thanh Ngoc; Choi, Gyung Ja; Choi, Yong Ho; Jang, Kyoung Soo; Park, Youn-Je; Kim, Jin-Cheol


    This research examines the acid hydrolysis of Curcuma longa waste, to obtain the hydrolysate containing lactic acid and ethanol fermentative sugars. A central composite design for describing regression equations of variables was used. The selected optimum condition was 4.91% sulphuric acid, 122.68°C and 50 min using the desirability function under the following conditions: the maximum reducing sugar (RS) yield is within the limited range of the 5-hydroxymethylfurfural (HMF) and furfural concentrations. Under the condition, the obtained solution contained 144 g RS/L, 0.79 g furfural/L and 2.59 g HMF/L and was directly fermented without a detoxification step. The maximum product concentration, average productivity, RS conversion and product yield were 115.36 g/L, 2.88 g/L/h, 89.43% and 64% for L-lactic acid; 113.92 g/L, 2.59 g/L/h, 88.31% and 63.29% for D-lactic acid; and 55.03 g/L, 1.38 g/L/h, 42.66 and 30.57%, respectively, for ethanol using a 7-L jar fermenter.

  14. Combined process for ethanol fermentation at high-solids loading and biogas digestion from unwashed steam-exploded corn stover. (United States)

    Wang, Zhen; Lv, Zhe; Du, Jiliang; Mo, Chunling; Yang, Xiushan; Tian, Shen


    A combined process was designed for the co-production of ethanol and methane from unwashed steam-exploded corn stover. A terminal ethanol titer of 69.8 g/kg mass weight (72.5%) was achieved when the fed-batch mode was performed at a final solids loading of 35.5% (w/w) dry matter (DM) content. The whole stillage from high-solids ethanol fermentation was directly transferred in a 3-L anaerobic digester. During 52-day single-stage digester operation, the methane productivity was 320 mL CH₄/g volatile solids (VS) with a maximum VS reduction efficiency of 55.3%. The calculated overall product yield was 197 g ethanol + 96 g methane/kg corn stover. This indicated that the combined process was able to improve overall content utilization and extract a greater yield of lignocellulosic biomass compared to ethanol fermentation alone.

  15. Modeling and optimization of ethanol fermentation using Saccharomyces cerevisiae: Response surface methodology and artificial neural network

    Directory of Open Access Journals (Sweden)

    Esfahanian Mehri


    Full Text Available In this study, the capabilities of response surface methodology (RSM and artificial neural networks (ANN for modeling and optimization of ethanol production from glucoseusing Saccharomyces cerevisiae in batch fermentation process were investigated. Effect of three independent variables in a defined range of pH (4.2-5.8, temperature (20-40ºC and glucose concentration (20-60 g/l on the cell growth and ethanol production was evaluated. Results showed that prediction accuracy of ANN was apparently similar to RSM. At optimum condition of temperature (32°C, pH (5.2 and glucose concentration (50 g/l suggested by the statistical methods, the maximum cell dry weight and ethanol concentration obtained from RSM were 12.06 and 16.2 g/l whereas experimental values were 12.09 and 16.53 g/l, respectively. The present study showed that using ANN as fitness function, the maximum cell dry weight and ethanol concentration were 12.05 and 16.16 g/l, respectively. Also, the coefficients of determination for biomass and ethanol concentration obtained from RSM were 0.9965 and 0.9853 and from ANN were 0.9975 and 0.9936, respectively. The process parameters optimization was successfully conducted using RSM and ANN; however prediction by ANN was slightly more precise than RSM. Based on experimental data maximum yield of ethanol production of 0.5 g ethanol/g substrate (97 % of theoretical yield was obtained.

  16. High temperature stimulates acetic acid accumulation and enhances the growth inhibition and ethanol production by Saccharomyces cerevisiae under fermenting conditions. (United States)

    Woo, Ji-Min; Yang, Kyung-Mi; Kim, Sae-Um; Blank, Lars M; Park, Jin-Byung


    Cellular responses of Saccharomyces cerevisiae to high temperatures of up to 42 °C during ethanol fermentation at a high glucose concentration (i.e., 100 g/L) were investigated. Increased temperature correlated with stimulated glucose uptake to produce not only the thermal protectant glycerol but also ethanol and acetic acid. Carbon flux into the tricarboxylic acid (TCA) cycle correlated positively with cultivation temperature. These results indicate that the increased demand for energy (in the form of ATP), most likely caused by multiple stressors, including heat, acetic acid, and ethanol, was matched by both the fermentation and respiration pathways. Notably, acetic acid production was substantially stimulated compared to that of other metabolites during growth at increased temperature. The acetic acid produced in addition to ethanol seemed to subsequently result in adverse effects, leading to increased production of reactive oxygen species. This, in turn, appeared to cause the specific growth rate, and glucose uptake rate reduced leading to a decrease of the specific ethanol production rate far before glucose depletion. These results suggest that adverse effects from heat, acetic acid, ethanol, and oxidative stressors are synergistic, resulting in a decrease of the specific growth rate and ethanol production rate and, hence, are major determinants of cell stability and ethanol fermentation performance of S. cerevisiae at high temperatures. The results are discussed in the context of possible applications.

  17. Optimization of saccharification and ethanol production by simultaneous saccharification and fermentation (SSF) from seaweed, Saccharina japonica. (United States)

    Jang, Ji-Suk; Cho, YuKyeong; Jeong, Gwi-Taek; Kim, Sung-Koo


    Ethanol was produced using the simultaneous saccharification and fermentation (SSF) method with macroalgae polysaccharide from the seaweed Saccharina japonica (Sea tangle, Dasima) as biomass. The seaweed was dried by hot air, ground with a hammer mill and filtered with a 200-mesh sieve prior to pretreatment. Saccharification was carried out by thermal acid hydrolysis with H(2)SO(4) and the industrial enzyme, Termamyl 120 L. To increase the yield of saccharification, isolated marine bacteria were used; the optimal saccharification conditions were 10% (w/v) seaweed slurry, 40 mM H(2)SO(4) and 1 g dcw/L isolated Bacillus sp. JS-1. Using this saccharification procedure, the reducing sugar concentration and viscosity were 45.6 ± 5.0 g/L and 24.9 cp, respectively, and the total yield of the saccharification with optimal conditions and S. japonica was 69.1%. Simultaneous saccharification and fermentation was carried out for ethanol production. The highest ethanol concentration, 7.7 g/L (9.8 ml/L) with a theoretical yield of 33.3%, was obtained by SSF with 0.39 g dcw/L Bacillus sp. JS-1 and 0.45 g dcw/L of the yeast, Pichia angophorae KCTC 17574.

  18. Development of High-Productivity Continuous Ethanol Production using PVA-Immobilized Zymomonas mobilis in an Immobilized-Cells Fermenter

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    Nurhayati Nurhayati


    Full Text Available Ethanol as one of renewable energy was being considered an excellent alternative clean-burning fuel to replace gasoline. Continuous ethanol fermentation systems had offered important economic advantages compared to traditional systems. Fermentation rates were significantly improved, especially when continuous fermentation was integrated with cell immobilization techniques to enrich the cells concentration in fermentor. Growing cells of Zymomonas mobilis immobilized in polyvinyl alcohol (PVA gel beads were employed in an immobilized-cells fermentor for continuous ethanol fermentation from glucose. The glucose loading, dilution rate, and cells loading were varied in order to determine which best condition employed in obtaining both high ethanol production and low residual glucose with high dilution rate. In this study, 20 g/L, 100 g/L, 125 g/L and 150 g/L of glucose concentration and 20% (w/v, 40% (w/v and 50% (w/v of cells loading were employed with range of dilution rate at 0.25 to 1 h-1. The most stable production was obtained for 25 days by employing 100 g/L of glucose loading. Meanwhile, the results also exhibited that 125 g/L of glucose loading as well as 40% (w/v of cells loading yielded high ethanol concentration, high ethanol productivity, and acceptable residual glucose at 62.97 g/L, 15.74 g/L/h and 0.16 g/L, respectively. Furthermore, the dilution rate of 4 hour with 100 g/L and 40% (w/v of glucose and cells loading was considered as the optimum condition with ethanol production, ethanol productivity and residual glucose obtained were 49.89 g/L, 12.47 g/L/h, and 2.04 g/L, respectively. This recent study investigated ethanol inhibition as well. The present research had proved that high sugar concentration was successfully converted to ethanol. These achieved results were promising for further study.

  19. Isolation, identification and optimization of ethanol producing bacteria from Saccharomyces-based fermentation process of alcohol industries in Iran

    Directory of Open Access Journals (Sweden)

    Hoda Ebrahimi


    Full Text Available Introduction: Due to the vast growth of world population, consumption of a lot of energy, limited energy supply and rising prices of fuel oil in the future, other alternative energy source is essential. Ethanol is renewable and a safe fuel and it is mainly based on microbial fermentation. The purpose of this study was isolation of high ethanol producing bacteria from the fermentation process of alcohol industries and optimization of growth conditions to be introduced to the industries. Materials and methods: The samples that were collected from fermentation tanks of alcohol industries were enriched in ZSM medium. To isolate the ethanol producing bacteria, the enriched culture was transferred on RMA agar. Bacterial growth conditions and their effects on ethanol production were optimized based on pH, growth temperature, agitation, fermentation time, initial substrate concentration and carbon and nitrogen sources. In addition, the morphological, physiological and molecular characterizations were investigated for identification of the isolates.Results: Three bacterial isolates ZYM7, ZYM8 and ZYM9 were isolated from fermentation tank. All isolates were able to produce ethanol 5.00, 7.60 and 4.00 gL-1 after 48 hours, respectively. The results demonstrated that all isolates were able to consume most sugars sources specially pentose carbon xylose. The isolate ZYM7 produced 13.00 gL-1 ethanol by consumption of xylose. The results of morphological and physiological characteristics showed that ZYM7 belonged to Lactobacillus sp. and ZYM8 and ZYM9 belonged to Acetobacter sp. Moreover, 16S rRNA sequencing and phylogenetic analyses exhibited that ZYM7 was similar to Lactobacillus rhamnosus with 99% homology and ZYM8 and ZYM9 were similar to Acetobacter pasteurianus with 99 and 98% homology, respectively.Discussion and conclusion: The results showed that that the isolated bacteria were suitable candidates to produce ethanol from raw material enriched with

  20. Sequential enzymatic saccharification and fermentation of ionic liquid and organosolv pretreated agave bagasse for ethanol production. (United States)

    Pérez-Pimienta, Jose A; Vargas-Tah, Alejandra; López-Ortega, Karla M; Medina-López, Yessenia N; Mendoza-Pérez, Jorge A; Avila, Sayeny; Singh, Seema; Simmons, Blake A; Loaces, Inés; Martinez, Alfredo


    Agave bagasse (AGB) has gained recognition as a drought-tolerant biofuel feedstock with high productivity in semiarid regions. A comparative analysis of ionic liquid (IL) and organosolv (OV) pretreatment technologies in AGB was performed using a sequential enzymatic saccharification and fermentation (SESF) strategy with cellulolytic enzymes and the ethanologenic Escherichia coli strain MS04. After pretreatment, 86% of xylan and 45% of lignin were removed from OV-AGB, whereas IL-AGB reduced lignin content by 28% and xylan by 50% when compared to the untreated biomass. High glucan (>90%) and xylan (>83%) conversion was obtained with both pretreated samples. During the fermentation stage (48h), 12.1 and 12.7kg of ethanol were produced per 100kg of untreated AGB for IL and OV, respectively. These comparative analyses showed the advantages of SESF using IL and OV in a biorefinery configuration where a better understanding of AGB recalcitrance is key for future applications.

  1. Integrated, systems metabolic picture of acetone-butanol-ethanol fermentation by Clostridium acetobutylicum. (United States)

    Liao, Chen; Seo, Seung-Oh; Celik, Venhar; Liu, Huaiwei; Kong, Wentao; Wang, Yi; Blaschek, Hans; Jin, Yong-Su; Lu, Ting


    Microbial metabolism involves complex, system-level processes implemented via the orchestration of metabolic reactions, gene regulation, and environmental cues. One canonical example of such processes is acetone-butanol-ethanol (ABE) fermentation by Clostridium acetobutylicum, during which cells convert carbon sources to organic acids that are later reassimilated to produce solvents as a strategy for cellular survival. The complexity and systems nature of the process have been largely underappreciated, rendering challenges in understanding and optimizing solvent production. Here, we present a system-level computational framework for ABE fermentation that combines metabolic reactions, gene regulation, and environmental cues. We developed the framework by decomposing the entire system into three modules, building each module separately, and then assembling them back into an integrated system. During the model construction, a bottom-up approach was used to link molecular events at the single-cell level into the events at the population level. The integrated model was able to successfully reproduce ABE fermentations of the WT C. acetobutylicum (ATCC 824), as well as its mutants, using data obtained from our own experiments and from literature. Furthermore, the model confers successful predictions of the fermentations with various network perturbations across metabolic, genetic, and environmental aspects. From foundation to applications, the framework advances our understanding of complex clostridial metabolism and physiology and also facilitates the development of systems engineering strategies for the production of advanced biofuels.

  2. Butanol production in acetone-butanol-ethanol fermentation with in situ product recovery by adsorption. (United States)

    Xue, Chuang; Liu, Fangfang; Xu, Mengmeng; Tang, I-Ching; Zhao, Jingbo; Bai, Fengwu; Yang, Shang-Tian


    Activated carbon Norit ROW 0.8, zeolite CBV901, and polymeric resins Dowex Optipore L-493 and SD-2 with high specific loadings and partition coefficients were studied for n-butanol adsorption. Adsorption isotherms were found to follow Langmuir model, which can be used to estimate the amount of butanol adsorbed in acetone-butanol-ethanol (ABE) fermentation. In serum-bottle fermentation with in situ adsorption, activated carbon showed the best performance with 21.9g/L of butanol production. When operated in a fermentor, free- and immobilized-cell fermentations with adsorption produced 31.6g/L and 54.6g/L butanol with productivities of 0.30g/L·h and 0.45g/L·h, respectively. Thermal desorption produced a condensate containing ∼167g/L butanol, which resulted in a highly concentrated butanol solution of ∼640g/L after spontaneous phase separation. This in situ product recovery process with activated carbon is energy efficient and can be easily integrated with ABE fermentation for n-butanol production.

  3. Acetone-butanol-ethanol production from Kraft paper mill sludge by simultaneous saccharification and fermentation. (United States)

    Guan, Wenjian; Shi, Suan; Tu, Maobing; Lee, Yoon Y


    Paper mill sludge (PS), a solid waste from pulp and paper industry, was investigated as a feedstock for acetone-butanol-ethanol (ABE) production by simultaneous saccharification and fermentation (SSF). ABE fermentation of paper sludge by Clostridium acetobutylicum required partial removal of ash in PS to enhance its enzymatic digestibility. Enzymatic hydrolysis was found to be a rate-limiting step in the SSF. A total of 16.4-18.0g/L of ABE solvents were produced in the SSF of de-ashed PS with solid loading of 6.3-7.4% and enzyme loading of 10-15FPU/g-glucan, and the final solvent yield reached 0.27g/g sugars. No pretreatment and pH control were needed in ABE fermentation of paper sludge, which makes it an attractive feedstock for butanol production. The results suggested utilization of paper sludge should not only consider the benefits of buffering effect of CaCO3 in fermentation, but also take into account its inhibitory effect on enzymatic hydrolysis.

  4. Effects of particulate materials and osmoprotectants on very-high-gravity ethanolic fermentation by Saccharomyces cerevisiae. (United States)

    Thomas, K C; Hynes, S H; Ingledew, W M


    The effects of osmoprotectants (such as glycine betaine and proline) and particulate materials on the fermentation of very high concentrations of glucose by the brewing strain Saccharomyces cerevisiae (uvarum) NCYC 1324 were studied. The yeast growing at 20 degrees C consumed only 15 g of the sugar per 100 ml from a minimal medium which initially contained 35% (wt/vol) glucose. Supplementing the medium with a mixture of glycine betaine, glycine, and proline increased the amount of sugar fermented to 30.5 g/100 ml. With such supplementation, the viability of the yeast cells was maintained above 80% throughout the fermentation, while it dropped to less than 12% in the unsupplemented controls. Among single additives, glycine was more effective than proline or glycine betaine. On incubating the cultures for 10 days, the viability decreased to only 55% with glycine, while it dropped to 36 and 27%, respectively, with glycine betaine and proline. It is suggested that glycine and proline, known to be poor nitrogen sources for growth, may serve directly or indirectly as osmoprotectants. Nutrients such as tryptone, yeast extract, and a mixture of purine and pyrimidine bases increased the sugar uptake and ethanol production but did not allow the population to maintain the high level of cell viability. While only 43% of the sugar was fermented in unsupplemented medium, the presence of particulate materials such as wheat bran, wheat mash insolubles, alumina, and soy flour increased sugar utilization to 68, 75, 81, and 82%, respectively.

  5. Comparing the fermentation performance of Escherichia coli KO11, Saccharomyces cerevisiae 424A(LNH-ST and Zymomonas mobilis AX101 for cellulosic ethanol production

    Directory of Open Access Journals (Sweden)

    Dale Bruce E


    Full Text Available Abstract Background Fermentations using Escherichia coli KO11, Saccharomyces cerevisiae 424A(LNH-ST, and Zymomonas mobilis AX101 are compared side-by-side on corn steep liquor (CSL media and the water extract and enzymatic hydrolysate from ammonia fiber expansion (AFEX-pretreated corn stover. Results The three ethanologens are able produce ethanol from a CSL-supplemented co-fermentation at a metabolic yield, final concentration and rate greater than 0.42 g/g consumed sugars, 40 g/L and 0.7 g/L/h (0-48 h, respectively. Xylose-only fermentation of the tested ethanologenic bacteria are five to eight times faster than 424A(LNH-ST in the CSL fermentation. All tested strains grow and co-ferment sugars at 15% w/v solids loading equivalent of ammonia fiber explosion (AFEX-pretreated corn stover water extract. However, both KO11 and 424A(LNH-ST exhibit higher growth robustness than AX101. In 18% w/w solids loading lignocellulosic hydrolysate from AFEX pretreatment, complete glucose fermentations can be achieved at a rate greater than 0.77 g/L/h. In contrast to results from fermentation in CSL, S. cerevisiae 424A(LNH-ST consumed xylose at the greatest extent and rate in the hydrolysate compared to the bacteria tested. Conclusions Our results confirm that glucose fermentations among the tested strains are effective even at high solids loading (18% by weight. However, xylose consumption in the lignocellulosic hydrolysate is the major bottleneck affecting overall yield, titer or rate of the process. In comparison, Saccharomyces cerevisiae 424A(LNH-ST is the most relevant strains for industrial production for its ability to ferment both glucose and xylose from undetoxified and unsupplemented hydrolysate from AFEX-pretreated corn stover at high yield.

  6. Simultaneous saccharification and fermentation of steam-pretreated lespedeza stalks for the production of ethanol

    Institute of Scientific and Technical Information of China (English)

    Jiang Jian-xin; Zhu Li-wei; Wang Kun; Wang Wei-gan


    Lespedeza stalks were subjected to steam pretreatment at 210℃ for some steaming time before simultaneous saccharification and fermentation (SSF). Cellulose-derived glucose was extensively utilized by yeast during SSF. The ethanol yields after steam pretreatment of the lespedeza stalks at 210℃ were 59.3%, 72.8% and 62.2% of the theoretically expected values when the steaming times were 2, 4 and 6 min, respectively. The highest yield from α-cellulose was 92.7% of the theoretical value. Steam explosion pretreatment of lespedeza stalks increased ethanol yields by a factor of 4.4, from 16.4% (untreated) to 72.8% (steam explosion pretreated).

  7. Alcoholic fermentation by the wild yeasts under thermal, osmotic and ethanol stress

    Directory of Open Access Journals (Sweden)

    Rosimeire Oenning da Silva


    Full Text Available This study aimed to explore the variability in the metabolism of nine wild yeasts isolated from the sugarcane juice from a distillery in the Brazilian State of Mato Grosso. Cell viability under the stress conditions was evaluated. The yeasts were inoculated in the test tubes containing sugarcane juice adjusted from 12 to 21º Brix, ethanol from 6 to 12% in volume and temperature at 30, 35 and 40ºC. The viability was established by the growth in Petri dishes and visually by the CO2 production in the test tubes. None of the evaluated yeasts showed simultaneous resistance to the three stress conditions. The potential of yeast BB.09 could be emphasized due to its ability to ferment up to12% ethanol at 30°C.

  8. A mathematical model of ethanol fermentation from cheese whey. I: Model development and parameter estimation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chen-Jen; Bajpai, R.K. [Univ. of Missouri, Columbia, MO (United States)


    The cybernetic approach to modeling of microbial kinetics in a mixed-substrate environment has been used in this work for the fermentative production of ethanol from cheese whey. In this system, the cells grow on multiple substrates and generate metabolic energy during product formation. This article deals with the development of a mathematical model in which the concept of cell maintenance was modified in light of the specific nature of product formation. Continuous culture data for anaerobic production of ethanol by Kluyveromyces marxianus CBS 397 on glucose and lactose were used to estimate the kinetic parameters for subsequent use in predicting the behavior of microbial growth and product formation in new situations. 28 refs., 4 figs., 2 tabs.

  9. Production of ethanol by raw starch hydrolysis and fermentation of damaged grains of wheat and sorghum

    Energy Technology Data Exchange (ETDEWEB)

    Suresh, K.; Kiransree, N.; Venkateswar Rao, L. [Osmania Univ., Hyderabad (India). Dept. of Microbiology


    The simultaneous saccharification and fermentation was used to produce ethanol from raw starch of damaged quality wheat and sorghum grains by utilising crude amylase preparation from B. subtilis VB2 and an amylolytic yeast strain S. cerevisiae VSJ4. Various concentrations of damaged wheat and sorghum starch from 10% to 30%W/V were used and 25% was found to be optimum for damaged wheat and sorghum starch yielding 4.40%V/V and 3.50%V/V ethanol respectively. Whereas 25% raw starch of fine quality wheat and sorghum grains gave an yield of 5.60%V/V and 5.00%V/V respectively. The process was carried out at 35 C, 5.8 pH and 200 rpm for 4 days. (orig.) With 2 figs., 4 tabs., 14 refs.

  10. Ethanol Production from Whey by Kluyveromyces marxianus in Batch Fermentation System: Kinetics Parameters Estimation

    Directory of Open Access Journals (Sweden)

    Dessy Ariyanti


    Full Text Available Whey is the liquid remaining after milk has been curdled and strained. It is a by-product of the manufacture of cheese or casein and has several commercial uses. In environmental point of view, whey is kind of waste which has high pollution level due to it’s contain high organic compound with BOD and COD value 50 and 80 g/L respectively. On the other side, whey also contain an amount of lactose (4.5%-5%; lactose can be used as carbon source and raw material for producing ethanol via fermentation using yeast strain Kluyveromyces marxianus. The objective of this research is to investigate the ethanol production kinetics from crude whey through fermentation using Kluyveromyces marxianus and to predict the model kinetics parameter. The yeast was able to metabolize most of the lactose within 16 h to give 8.64 g/L ethanol, 4.43 g/L biomass, and remain the 3.122 g/L residual lactose. From the results presented it also can be concluded that common kinetic model for microbial growth, substrate consumption, and product formation is a good alternative to describe an experimental batch fermentation of Kluyveromyces marxianus grown on a medium composed of whey. The model was found to be capable of reflecting all batch culture phases to a certain degree of accuracy, giving the parameter value: μmax, Ks, YX/S, α, β : 0.32, 10.52, 0.095, 1.52, and 0.11 respectively. © 2013 BCREC UNDIP. All rights reserved(Selected Paper from International Conference on Chemical and Material Engineering (ICCME 2012Received: 27th September 2012; Revised: 29th November 2012; Accepted: 7th December 2012[How to Cite: D. Ariyanti, H. Hadiyanto, (2013. Ethanol Production from Whey by Kluyveromyces marxianus in Batch Fermentation System: Kinetics Parameters Estimation. Bulletin of Chemical Reaction Engineering & Catalysis, 7 (3: 179-184. (doi:10.9767/bcrec.7.3.4044.179-184][Permalink/DOI: ] View in  |

  11. An integrated platform for gas-diffusion separation and electrochemical determination of ethanol on fermentation broths

    Energy Technology Data Exchange (ETDEWEB)

    Giordano, Gabriela Furlan [Microfabrication Laboratory, Brazilian Nanotechnology National Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, SP 13083-970 (Brazil); Department of Analytical Chemistry, Institute of Chemistry – UNICAMP, Campinas, SP 13083-970 (Brazil); National Institute of Science and Technology of Bioanalytics, Institute of Chemistry – UNICAMP, Campinas, SP 13083-970 (Brazil); Vieira, Luis Carlos Silveira; Gobbi, Angelo Luiz [Microfabrication Laboratory, Brazilian Nanotechnology National Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, SP 13083-970 (Brazil); Lima, Renato Sousa [Microfabrication Laboratory, Brazilian Nanotechnology National Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, SP 13083-970 (Brazil); Department of Analytical Chemistry, Institute of Chemistry – UNICAMP, Campinas, SP 13083-970 (Brazil); National Institute of Science and Technology of Bioanalytics, Institute of Chemistry – UNICAMP, Campinas, SP 13083-970 (Brazil); Kubota, Lauro Tatsuo, E-mail: [Department of Analytical Chemistry, Institute of Chemistry – UNICAMP, Campinas, SP 13083-970 (Brazil); National Institute of Science and Technology of Bioanalytics, Institute of Chemistry – UNICAMP, Campinas, SP 13083-970 (Brazil)


    Highlights: • Integrated platform was developed to determine ethanol in fermentation broths. • The designed system integrates gas diffusion separation with voltammetric detection. • Detector relied on Ni(OH){sub 2}-modified electrode stabilized by Co{sup 2+} and Cd{sup 2+} insertion. • Separation was made by PTFE membrane separating sample from electrolyte (receptor). • Despite the sample complexity, accurate tests were achieved by direct interpolation. - Abstract: An integrated platform was developed for point-of-use determination of ethanol in sugar cane fermentation broths. Such analysis is important because ethanol reduces its fuel production efficiency by altering the alcoholic fermentation step when in excess. The custom-designed platform integrates gas diffusion separation with voltammetric detection in a single analysis module. The detector relied on a Ni(OH){sub 2}-modified electrode. It was stabilized by uniformly depositing cobalt and cadmium hydroxides as shown by XPS measurements. Such tests were in accordance with the hypothesis related to stabilization of the Ni(OH){sub 2} structure by insertion of Co{sup 2+} and Cd{sup 2+} ions in this structure. The separation step, in turn, was based on a hydrophobic PTFE membrane, which separates the sample from receptor solution (electrolyte) where the electrodes were placed. Parameters of limit of detection and analytical sensitivity were estimated to be 0.2% v/v and 2.90 μA % (v/v){sup −1}, respectively. Samples of fermentation broth were analyzed by both standard addition method and direct interpolation in saline medium based-analytical curve. In this case, the saline solution exhibited ionic strength similar to those of the samples intended to surpass the tonometry colligative effect of the samples over analyte concentration data by attributing the reduction in quantity of diffused ethanol vapor majorly to the electrolyte. The approach of analytical curve provided rapid, simple and accurate

  12. Increasing ethanol productivity during xylose fermentation by cell recycling of recombinant Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Roca, Christophe Francois Aime; Olsson, Lisbeth


    The influence of cell recycling of xylose-fermenting Saccharomyces cerevisiae TMB3001 was investigated during continuous cultivation on a xylose-glucose mixture. By using cell recycling at the dilution rate (D) of 0.05 h(-1), the cell-mass concentration could be increased from 2.2 g l(-1) to 22 g l...... ethanol productivity was in the range of 0.23-0.26 g g(-1) h(-1) with or without cell recycling, showing that an increased cell-mass concentration did not influence the efficiency of the yeast....

  13. Acetone-butanol-ethanol from sweet sorghum juice by an immobilized fermentation-gas stripping integration process. (United States)

    Cai, Di; Wang, Yong; Chen, Changjing; Qin, Peiyong; Miao, Qi; Zhang, Changwei; Li, Ping; Tan, Tianwei


    In this study, sweet sorghum juice (SSJ) was used as the substrate in a simplified ABE fermentation-gas stripping integration process without nutrients supplementation. The sweet sorghum bagasse (SSB) after squeezing the fermentable juice was used as the immobilized carrier. The results indicated that the productivity of ABE fermentation process was improved by gas stripping integration. A total 24g/L of ABE solvents was obtained from 59.6g/L of initial sugar after 80h of fermentation with gas stripping. Then, long-term of fed-batch fermentation with continuous gas stripping was further performed. 112.9g/L of butanol, 44.1g/L of acetone, 9.5g/L of ethanol (total 166.5g/L of ABE) was produced in overall 312h of fermentation. At the same time, concentrated ABE product was obtained in the condensate of gas stripping.

  14. Effect of the corn grain storage method on saccharification and ethanol fermentation field

    Directory of Open Access Journals (Sweden)

    Jacek Nowak


    Full Text Available The chemical conservation was chosen in the study as the method for preserving fresh corn grain for distilleries. Five types of preserved corn samples were prepared. The control (with no additives and four preserved with the preparation, based on formic and propionic acids (KemiSile 2000 Plus, at different levels. All the samples were stored for two months. Ethanol fermentations of low-temperature-cooked and pressure-cooked corn starch were carried out using commercial distillery yeast. The yeast strain, after starch hydrolysis with two enzymes, was able to produce 86-93% of theoretical ethanol yield from low-temperature-cooked corn. The ethanol production was almost equal to that produced from pressure-cooked corn starch (121°C, which was 87-94% of theoretical ethanol yield. The quality of distillates was also investigated. The most common by-products found were: acetaldehyde, ethyl acetate, propanol, isobutanol and 3-metylo-1-butanol. There were no important differences of spirits chemical composition between low-temperature- -cooking and pressure-cooking method as well as between the kind of corn sample.

  15. Production of cellulosic ethanol from sugarcane bagasse by steam explosion: Effect of extractives content, acid catalysis and different fermentation technologies. (United States)

    Neves, P V; Pitarelo, A P; Ramos, L P


    The production of cellulosic ethanol was carried out using samples of native (NCB) and ethanol-extracted (EECB) sugarcane bagasse. Autohydrolysis (AH) exhibited the best glucose recovery from both samples, compared to the use of both H3PO4 and H2SO4 catalysis at the same pretreatment time and temperature. All water-insoluble steam-exploded materials (SEB-WI) resulted in high glucose yields by enzymatic hydrolysis. SHF (separate hydrolysis and fermentation) gave ethanol yields higher than those obtained by SSF (simultaneous hydrolysis and fermentation) and pSSF (pre-hydrolysis followed by SSF). For instance, AH gave 25, 18 and 16 g L(-1) of ethanol by SHF, SSF and pSSF, respectively. However, when the total processing time was taken into account, pSSF provided the best overall ethanol volumetric productivity of 0.58 g L(-1) h(-1). Also, the removal of ethanol-extractable materials from cane bagasse had no influence on the cellulosic ethanol production of SEB-WI, regardless of the fermentation strategy used for conversion.

  16. Xylose fermentation to biofuels (hydrogen and ethanol) by extreme thermophilic (70 C) mixed culture

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Chenxi [Department of Environmental Science and Engineering, Tsinghua University, Beijing 100084 (China); Department of Environmental Engineering, Technical University of Denmark, DK-2800, Kgs Lyngby (Denmark); Karakashev, Dimitar; Angelidaki, Irini [Department of Environmental Engineering, Technical University of Denmark, DK-2800, Kgs Lyngby (Denmark); Lu, Wenjing; Wang, Hongtao [Department of Environmental Science and Engineering, Tsinghua University, Beijing 100084 (China)


    Combined biohydrogen and bioethanol (CHE) production from xylose was achieved by an extreme thermophilic (70 C) mixed culture. Effect of initial pH, xylose, peptone, FeSO{sub 4}, NaHCO{sub 3}, yeast extract, trace mineral salts, vitamins, and phosphate buffer concentrations on bioethanol and biohydrogen yield was investigated in batch experiments. Results obtained showed that initial pH, concentration of xylose, peptone, and FeSO{sub 4} significantly affected biohydrogen and bioethanol production, while the concentration of NaHCO{sub 3} was only significant for bioethanol production. By changing cultivation conditions the culture could be directed to mainly produce ethanol with maximum ethanol yield of 1.60 mol ethanol/mol-xylose corresponding to 95.8% of the theoretical ethanol yield based on degradation of xylose through ethanologenic pathway, or mainly hydrogen with maximum hydrogen yield of 1.84 mol H{sub 2}/mol-xylose corresponding to 55% of the theoretical hydrogen yield based on acetate metabolic pathway. An empirical model was established to reveal the quantitative effect of factors significant for biohydrogen (quadratic model) production and for bioethanol (linear model) production. Changes in hydrogen/ethanol yields observed were due to the shift of the metabolic pathway between ethanol or hydrogen production, rather than changes in bacterial community composition at genus level. Thermoanaerobacter related bacteria were found to be the dominant hydrogen/ethanol producers. (author)

  17. Oil palm empty fruit bunch to biofuels and chemicals via SO2-ethanol-water fractionation and ABE fermentation. (United States)

    Sklavounos, Evangelos; Iakovlev, Mikhail; Survase, Shrikant; Granström, Tom; van Heiningen, Adriaan


    A process has been developed for conversion of spent liquor produced by SO2-ethanol-water (SEW) fractionation of oil palm empty fruit bunch (OPEFB) fibers to biofuels by ABE fermentation. The fermentation process utilizes Clostridia bacteria that produce butanol, ethanol and acetone solvents at a total yield of 0.26 g/g sugars. A conditioning scheme is developed, which demonstrates that it is possible to utilize the hemicellulose sugars from this agricultural waste stream by traditional ABE fermentation. Fractionation as well as sugar hydrolysis in the spent liquor is hindered by the high cation content of OPEFB, which can be partly removed by acidic leaching suggesting that a better deashing method is necessary. Furthermore, it is inferred that better and more selective lignin removal is needed during conditioning to improve liquor fermentability.

  18. Direct fermentation of raw starch using a Kluyveromyces marxianus strain that expresses glucoamylase and alpha-amylase to produce ethanol. (United States)

    Wang, Rongliang; Wang, Dongmei; Gao, Xiaolian; Hong, Jiong


    Raw starch and raw cassava tuber powder were directly and efficiently fermented at elevated temperatures to produce ethanol using the thermotolerant yeast Kluyveromyces marxianus that expresses α-amylase from Aspergillus oryzae as well as α-amylase and glucoamylase from Debaryomyces occidentalis. Among the constructed K. marxianus strains, YRL 009 had the highest efficiency in direct starch fermentation. Raw starch from corn, potato, cassava, or wheat can be fermented at temperatures higher than 40°C. At the optimal fermentation temperature 42°C, YRL 009 produced 66.52 g/L ethanol from 200 g/L cassava starch, which was the highest production among the selected raw starches. This production increased to 79.75 g/L ethanol with a 78.3% theoretical yield (with all cassava starch were consumed) from raw cassava starch at higher initial cell densities. Fermentation was also carried out at 45 and 48°C. By using 200 g/L raw cassava starch, 137.11 and 87.71 g/L sugar were consumed with 55.36 and 32.16 g/L ethanol produced, respectively. Furthermore, this strain could directly ferment 200 g/L nonsterile raw cassava tuber powder (containing 178.52 g/L cassava starch) without additional nutritional supplements to produce 69.73 g/L ethanol by consuming 166.07 g/L sugar at 42°C. YRL 009, which has consolidated bioprocessing ability, is the best strain for fermenting starches at elevated temperatures that has been reported to date.

  19. The development and microbiology of bioprocesses for the production of hydrogen and ethanol by dark fermentation

    Energy Technology Data Exchange (ETDEWEB)

    Koskinen, P.


    This work investigated the production of hydrogen and ethanol from carbohydrates by bacterial dark fermentation. Meso and thermophilic fermenters were enriched from the environment, and their H{sub 2} and/or ethanol production in batch determined. Continuous biofilm, suspended-cell and granular-cell processes for H{sub 2} or ethanol+H{sub 2} production from glucose were developed and studied. Dynamics of microbial communities in processes were determined based on the 16S rRNA gene sequence analyses. Mesophilic enrichment, obtained from anaerobic digester sludge, produced 1.24 mol-H{sub 2} mol-glucose-1 in batch assays. Hydrogen production by the enrichment in a mesophilic fluidized-bed bioreactor (FBR) was found to be unstable - prompt onset of H{sub 2} production along with butyrate-acetate was followed by rapid decrease and cease associated with propionate-acetate production. Intermittent batch (semi-continuous) operation allowed a momentary recovery of H{sub 2} production in the FBR. The highest H{sub 2} production rate (HPR) observed in FBR was 28.8 mmol h-1 L-1, which corresponded to a relatively high hydrogen yield (HY) of 1.90 mol-H{sub 2} mol-glucose-1. Mesophilic, completely-mixed column reactor (CMCR), with a similar inoculum and feed as used in the FBR, provided a prolonged H{sub 2} production for 5 months. Highest HPR observed in the CMCR was 18.8 mmol h-1 L-1 (HY of 1.70 mol-H{sub 2} mol-glucose-1), while it in general remained between 1 and 6 mmol h-1 L-1. Hydrogen production in the CMCR was decreased by shifts in microbial community metabolism from initial butyrate-acetate metabolism, first to ethanol-acetate, followed by acetate-dominated metabolism, and finally to propionate-acetate metabolism, which ceased H{sub 2} production. The transitions of dominant metabolisms were successfully detected and visualized by self-organizing maps (SOMs). Developed Clustering hybrid regression (CHR) model, performed well in modeling the HPR based on the data on

  20. Selection of hemicellulosic hydrolysate pretreatments and fermentation conditions to stimulate xylitol protection by ethanol-producing yeasts

    Energy Technology Data Exchange (ETDEWEB)

    Converti, A. [Ist. di Ingegneria Chimica e di Processo `G.B. Bonino`, Facolta di Ingegneria, Univ. degli Studi di Genova (Italy); Del Borghi, M. [Ist. di Ingegneria Chimica e di Processo `G.B. Bonino`, Facolta di Ingegneria, Univ. degli Studi di Genova (Italy)


    Xylitol production from hardwood hemicellulosic hydrolysates by well-known ethanol-producing yeasts was stimulated through an experimental schedule including pretreatments of the hydrolysate, the choice of the best xylitol producer and the selection of the optimum fermentation conditions. The xylitol or ethanol yields obtained on consumed xylose demonstrated that their production was stimulated under completely different conditions, as to be expected by the fact that these catabolites are the final products of different metabolic pathways. In particular, the catabolism of Pachysolen tannophilus, that is the best ethanol producer from this natural substrate, could be targeted towards xylitol rather than towards ethanol production by ensuring a strongly reducing environment through a suitable pretreatment of the hydrolysate. The final removal of fermentation inhibitors by adsorption onto highly adsorbing substances allowed a further 20% xylitol yield increase. (orig.)

  1. Ethanol production via simultaneous saccharification and fermentation of sodium hydroxide treated corn stover using Phanerochaete chrysosporium and Gloeophyllum trabeum. (United States)

    Vincent, Micky; Pometto, Anthony L; van Leeuwen, J Hans


    Ethanol was produced via the simultaneous saccharification and fermentation (SSF) of dilute sodium hydroxide treated corn stover. Saccharification was achieved by cultivating either Phanerochaete chrysosporium or Gloeophyllum trabeum on the treated stover, and fermentation was then performed by using either Saccharomyces cerevisiae or Escherichia coli K011. Ethanol production was highest on day 3 for the combination of G. trabeum and E. coli K011 at 6.68 g/100g stover, followed by the combination of P. chrysosporium and E. coli K011 at 5.00 g/100g stover. SSF with S. cerevisiae had lower ethanol yields, ranging between 2.88 g/100g stover at day 3 (P. chrysosporium treated stover) and 3.09 g/100g stover at day 4 (G. trabeum treated stover). The results indicated that mild alkaline pretreatment coupled with fungal saccharification offers a promising bioprocess for ethanol production from corn stover without the addition of commercial enzymes.

  2. Gamma radiation in some microbiological and biochemical parameters of ethanolic fermentation.; Efeito da radiacao gama em alguns parametros microbiologicos e bioquimicos da fermentacao alcoolica

    Energy Technology Data Exchange (ETDEWEB)

    Alcarde, Andre Ricardo


    The objective of this work was to evaluate the effect of gamma radiation in reducing the bacterial population of the sugar cane must and verify its influence in the ethanolic fermentation. For this purpose, some microbiological and biochemical parameters of the ethanolic fermentation were analyzed, such as bacterial count; viability, replication and living replicates of the yeast; p H, acidity (total and volatile), glycerol and production of organic acids (acetic, lactic and succinic) during the fermentation; and fermentative yield. Bacteria of the genera Bacillus and Lactobacillus are the most common contaminants of the ethanolic fermentation and they might cause a decrease in the fermentative yield. The ionizing radiations may affect the microorganisms altering the DNA of the cells, which lose the ability to reproduce themselves and die. The experimental design was in randomized blocks (three) with one replicate in each block. The must was sugar-cane juice with approximately 5% of total reducing sugar. Bacteria of the following species were tested: Bacillus subtilis, Bacillus coagulans, Lactobacillus plantarum and Lactobacillus fermentum. The experiments were the inoculation of each bacteria separately in the must, the inoculation of the mixture of the four bacteria in the must and the use of natural sugar-cane juice with its own contaminating microorganisms. The contaminated must was irradiated with the doses of 0.0 (control), 2.0,4.0, 6.0, 8.0 and 10.0 kGy of gamma radiation (60-Cobalt) at an average rate of 2.0 kGy/h. After the irradiation, the fermentation of the must was carried out using the yeast Saccharomyces cerevisiae (Fleischmann). It was also accomplished an experiment with the inoculation of the mixture of the four bacteria in the must and, instead of using gamma radiation to decontaminate the must, it was used the antimicrobial Kamoran ID in the concentration of 3 ppm. The effects of the irradiation of the must were: reduction of the bacterial

  3. Research progress on fungicides during ethanol fermentation%酒精发酵中杀菌剂的研究进展

    Institute of Scientific and Technical Information of China (English)



    酒精发酵是一个非常复杂的微生物反应过程。在这个过程中,除了生产菌外,还会从原料、空气、水等带入相当数量的杂菌,从而降低酒精得率,影响酒精的正常生产。因此如何有效控制杂菌的感染,对整个酒精生产至关重要。本文综述了酒精发酵中杀菌剂的研究进展,主要介绍了酒精发酵过程中染菌的原因、危害、检测方法以及常见的污染杂菌,重点介绍了漂白粉、青霉素、克菌灵、酒花及植物提取物等杀菌剂的使用。指出减少酒精发酵中的杂菌污染,加强细菌抗药性的研究,寻找安全天然杀菌剂替代品是未来研究的关键。%Ethanol fermentation is a complex microbial process. During the process,a significant number of bacteria will be brought in from raw materials,air,water,etc.,which will reduce yield of ethanol and affect production of ethanol. Therefore,how to effectively control the bacteria infection is essential for the ethanol production. Research progress on fungicides during ethanol fermentation was reviewed in this paper. The source,contamination,testing methods of the common harmful bacteria during ethanol fermentation were introduced focusing on the application of bleaching powder, penicillin,“kejunling” and hops and plant extracts. Reducing the bacteria infection during ethanol fermentation,strengthening the study of bacteria resistance and finding safe and natural alternatives to fungicides are the keys to future research.

  4. Optimization of a corn steep medium for production of ethanol from synthesis gas fermentation by Clostridium ragsdalei. (United States)

    Saxena, Jyotisna; Tanner, Ralph S


    Fermentation of biomass derived synthesis gas to ethanol is a sustainable approach that can provide more usable energy and environmental benefits than food-based biofuels. The effects of various medium components on ethanol production by Clostridium ragsdalei utilizing syngas components (CO:CO(2)) were investigated, and corn steep liquor (CSL) was used as an inexpensive nutrient source for ethanol production by C. ragsdalei. Elimination of Mg(2+), NH(4) (+) and PO(4) (3-) decreased ethanol production from 38 to 3.7, 23 and 5.93 mM, respectively. Eliminating Na(+), Ca(2+), and K(+) or increasing Ca(2+), Mg(2+), K(+), NH(4) (+) and PO(4) (3-) concentrations had no effect on ethanol production. However, increased Na(+) concentration (171 mM) inhibited growth and ethanol production. Yeast extract (0.5 g l(-1)) and trace metals were necessary for growth of C. ragsdalei. CSL alone did not support growth and ethanol production. Nutrients limiting in CSL were trace metals, NH(4) (+) and reducing agent (Cys: cysteine sulfide). Supplementation of trace metals, NH(4) (+) and CyS to CSL (20 g l(-1), wet weight basis) yielded better growth and similar ethanol production as compared to control medium. Using 10 g l(-1), the nutritional limitation led to reduced ethanol production. Higher concentrations of CSL (50 and 100 g l(-1)) were inhibitory for cell growth and ethanol production. The CSL could replace yeast extract, vitamins and minerals (excluding NH(4) (+)). The optimized CSL medium produced 120 and 50 mM of ethanol and acetate, respectively. The CSL could provide as an inexpensive source of most of the nutrients required for the syngas fermentation, and thus could improve the economics of ethanol production from biomass derived synthesis gas by C. ragsdalei.

  5. Ethanolic fermentation in whey and whey-molasses mixtures. Pt. 1. Influence of concentration and type of whey on the rate of fermentation

    Energy Technology Data Exchange (ETDEWEB)

    Zakrzewski, E.; Zmarlicki, S.


    Concentration of whey slowed down the rate of ethanolic fermentation carried out with the yeast Kluyveromyces marxianus subsp. marxianus. It was possible, however, to maintain a higher rate of ethanol production with increasing concentration of whey (up to about 17 g of lactose per 100 cm/sup 3/ of rennet whey and up to 12 g of lactose per 100 cm/sup 3/ of whey) if, irrespective of the concentration, the initial ratio of yeast dry solids to lactose in the different wheys was set up on the same level. Ethanol fermentation in concentrated whey was distinctly slower than in rennet whey or acid wheys obtained by artificial acidification of milk with lactic or sulphuric acid.

  6. [Continuous operation of hydrogen bio-production reactor with ethanol-type fermentation]. (United States)

    Ren, Nan-qi; Gong, Man-li; Xing, De-feng


    The natural response of a continuous stirred tank reactor (CSTR) for hydrogen bio-production using molasses wastewater as substrate was investigated. Emphasis was placed on assessing the operational controlling strategy on the stable operation of CSTR with high efficiency. It was found that at an initial biomass of 15g/L, an equilibrial microbial community in the ethanol-type fermentation and efficient stable operation of CSTR could be established with following conditions: temperature of 35 degrees C +/- 1 degrees C, COD organic loading rate (OLR) of 40kg/(m3 x d), hydraulic retention time (HRT) of 4h, pH value of 4.6 - 4.9 and oxidation reduction potential (ORP) of -450 - -470mV. Following that, hydrogen production in the reactor was relatively stable. The observed maximal hydrogen bio-production rate was 7.63m3/(m3 x d). The content of hydrogen in the biogas was about 40% - 58%. COD removal rate was between 22% - 26%. The total content of ethanol and acetic acid in the fermentative end products was above 80%.

  7. Ethanol production potential from fermented rice noodle wastewater treatment using entrapped yeast cell sequencing batch reactor (United States)

    Siripattanakul-Ratpukdi, Sumana


    Fermented rice noodle production generates a large volume of starch-based wastewater. This study investigated the treatment of the fermented rice noodle wastewater using entrapped cell sequencing batch reactor (ECSBR) compared to traditional sequencing batch reactor (SBR). The yeast cells were applied because of their potential to convert reducing sugar in the wastewater to ethanol. In present study, preliminary treatment by acid hydrolysis was performed. A yeast culture, Saccharomyces cerevisiae, with calcium alginate cell entrapment was used. Optimum yeast cell loading in batch experiment and fermented rice noodle treatment performances using ECSBR and SBR systems were examined. In the first part, it was found that the cell loadings (0.6-2.7 × 108 cells/mL) did not play an important role in this study. Treatment reactions followed the second-order kinetics with the treatment efficiencies of 92-95%. In the second part, the result showed that ECSBR performed better than SBR in both treatment efficiency and system stability perspectives. ECSBR maintained glucose removal of 82.5 ± 10% for 5-cycle treatment while glucose removal by SBR declined from 96 to 40% within the 5-cycle treatment. Scanning electron microscopic images supported the treatment results. A number of yeast cells entrapped and attached onto the matrix grew in the entrapment matrix.

  8. The deletion of YLR042c improves ethanolic xylose fermentation by recombinant Saccharomyces cerevisiae. (United States)

    Parachin, Nádia S; Bengtsson, Oskar; Hahn-Hägerdal, Bärbel; Gorwa-Grauslund, Marie-F


    In a recent study combining transcriptome analyses of a number of recombinant laboratory and industrial S. cerevisiae strains with improved xylose utilization and their respective control strains, the ORF YLR042c was identified as a downregulated gene and it was shown that the gene deletion improved aerobic growth on xylose in the tested strain background. In the present study, the influence of deleting YLR042c on xylose fermentation was investigated in two different xylose-fermenting strains: TMB3001, which expresses genes from the initial xylose catabolizing pathway, including heterologous xylose reductase (XR) and xylitol dehydrogenase (XDH) and endogenous xylulokinase (XK); and TMB3057, which, in addition to the initial xylose catabolizing pathway, overexpresses the endogenous genes encoding the non-oxidative pentose phosphate pathway enzymes. The deletion of YLR042c led to improved aerobic growth on xylose in both strain backgrounds. However, the effect was more significant in the strain with the poorer growth rate on xylose (TMB3001). Under anaerobic conditions, the deletion of YLR042c increased the specific xylose consumption rate and the ethanol and xylitol yields. In strain TMB3057, xylose consumption was also improved at low concentrations and during co-fermentation of xylose and glucose. The effect of the gene deletion and overexpression was also tested for different carbon sources. Altogether, these results suggest that YLR042c influences xylose and the assimilation of carbon sources other than glucose, and that the effect could be at the level of sugar transport or sugar signalling.

  9. Repeated-batch fermentation of lignocellulosic hydrolysate to ethanol using a hybrid Saccharomyces cerevisiae strain metabolically engineered for tolerance to acetic and formic acids. (United States)

    Sanda, Tomoya; Hasunuma, Tomohisa; Matsuda, Fumio; Kondo, Akihiko


    A major challenge associated with the fermentation of lignocellulose-derived hydrolysates is improved ethanol production in the presence of fermentation inhibitors, such as acetic and formic acids. Enhancement of transaldolase (TAL) and formate dehydrogenase (FDH) activities through metabolic engineering successfully conferred resistance to weak acids in a recombinant xylose-fermenting Saccharomyces cerevisiae strain. Moreover, hybridization of the metabolically engineered yeast strain improved ethanol production from xylose in the presence of both 30 mM acetate and 20mM formate. Batch fermentation of lignocellulosic hydrolysate containing a mixture of glucose, fructose and xylose as carbon sources, as well as the fermentation inhibitors, acetate and formate, was performed for five cycles without any loss of fermentation capacity. Long-term stability of ethanol production in the fermentation phase was not only attributed to the coexpression of TAL and FDH genes, but also the hybridization of haploid strains.

  10. Greenhouse gas emissions and production cost of ethanol produced from biosyngas fermentation process. (United States)

    Roy, Poritosh; Dutta, Animesh; Deen, Bill


    Life cycle (LC) of ethanol has been evaluated to determine the environmental and economical viability of ethanol that was derived from biosyngas fermentation process (gasification-biosynthesis). Four scenarios [S1: untreated (raw), S2: treated (torrefied); S3: untreated-chemical looping gasification (CLG), S4: treated-CLG] were considered. The simulated biosyngas composition was used in this evaluation process. The GHG emissions and production cost varied from 1.19 to 1.32 kg-CO2 e/L and 0.78 to 0.90$/L, respectively, which were found to be dependent on the scenarios. The environmental and economical viability was found be improved when untreated feedstock was used instead of treated feedstock. Although the GHG emissions slightly reduced in the case of CLG process, production cost was nominally increased because of the cost incurred by the use of CaO. This study revealed that miscanthus is a promising feedstock for the ethanol industry, even if it is grown on marginal land, which can help abate GHG emissions.

  11. Performance of a pinch analysis for the process of recovery of ethanol from fermentation

    Energy Technology Data Exchange (ETDEWEB)

    Khan, S.; Riverol, C. [Chemical Engineeering Department, University of West Indies (Trinidad and Tobago)


    The objectives of the project reported here were to perform an energy analysis for the process of the recovery of ethanol from fermentation broths by catalytic conversion to gasoline and to conduct a pinch analysis to obtain a new heat exchanger network, and thus, reduce the utility costs. A minimum temperature difference of 10 C was used. A temperature interval diagram and cascade diagram were drawn to identify the pinch points and four such points were observed. New heat exchanger networks were formulated from this information. The least number of heat exchangers for the different networks created was 19, whereas the original process had 9. The cost of utilities was the same for both systems. Therefore, it was concluded that the implementation of this system in the Caribbean could be expensive since in the first instance, ethanol is not particularly plentiful. Secondly, electricity and water costs are expensive in the Caribbean compared to other countries in America, such that any effort in reducing CO{sub 2} emissions by using ethanol would not be feasible. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  12. Ethanol fermentation of sugar beet thick juice diluted with crude cheese whey by the flex yeast Kluyveromyces marxianus KD-15


    Oda, Y.; Nakamura, K.; Shinomiya, N; Ohba, K.; 小田, 有二


    Kluyveromyces marxianus KD-15, called flex yeast, is a strain that is insensitive tocatabolite repression and has the capacity to produce ethanol efficiently from a mixtureof beet molasses and whey powder. When a fermentation test was conducted in 50 mLof a medium containing 200 mg mL-1 of sugar as sugar beet thick juice diluted with anarbitrary amount of crude whey, strain KD-15 produced over 99 mg mL-1 ethanol in allthe media tested, and ethanol formation decreased in proportion to the volu...

  13. Endogenous ethanol affects biopolyester molecular weight in recombinant Escherichia coli. (United States)

    Hiroe, Ayaka; Hyakutake, Manami; Thomson, Nicholas M; Sivaniah, Easan; Tsuge, Takeharu


    In biopolyester synthesis, polyhydroxyalkanoate (PHA) synthase (PhaC) catalyzes the polymerization of PHA in bacterial cells, followed by a chain transfer (CT) reaction in which the PHA polymer chain is transferred from PhaC to a CT agent. Accordingly, the frequency of CT reaction determines PHA molecular weight. Previous studies have shown that exogenous alcohols are effective CT agents. This study aimed to clarify the effect of endogenous ethanol as a CT agent for poly[(R)-3-hydroxybutyrate] [P(3HB)] synthesis in recombinant Escherichia coli, by comparing with that of exogenous ethanol. Ethanol supplementation to the culture medium reduced P(3HB) molecular weights by up to 56% due to ethanol-induced CT reaction. NMR analysis of P(3HB) polymers purified from the culture supplemented with (13)C-labeled ethanol showed the formation of a covalent bond between ethanol and P(3HB) chain at the carboxyl end. Cultivation without ethanol supplementation resulted in the reduction of P(3HB) molecular weight with increasing host-produced ethanol depending on culture aeration. On the other hand, production in recombinant BW25113(ΔadhE), an alcohol dehydrogenase deletion strain, resulted in a 77% increase in molecular weight. Analysis of five E. coli strains revealed that the estimated number of CT reactions was correlated with ethanol production. These results demonstrate that host-produced ethanol acts as an equally effective CT agent as exogenous ethanol, and the control of ethanol production is important to regulate the PHA molecular weight.

  14. Ethanol production from residual wood chips of cellulose industry: acid pretreatment investigation, hemicellulosic hydrolysate fermentation, and remaining solid fraction fermentation by SSF process. (United States)

    Silva, Neumara Luci Conceição; Betancur, Gabriel Jaime Vargas; Vasquez, Mariana Peñuela; Gomes, Edelvio de Barros; Pereira, Nei


    Current research indicates the ethanol fuel production from lignocellulosic materials, such as residual wood chips from the cellulose industry, as new emerging technology. This work aimed at evaluating the ethanol production from hemicellulose of eucalyptus chips by diluted acid pretreatment and the subsequent fermentation of the generated hydrolysate by a flocculating strain of Pichia stipitis. The remaining solid fraction generated after pretreatment was subjected to enzymatic hydrolysis, which was carried out simultaneously with glucose fermentation [saccharification and fermentation (SSF) process] using a strain of Saccharomyces cerevisiae. The acid pretreatment was evaluated using a central composite design for sulfuric acid concentration (1.0-4.0 v/v) and solid to liquid ratio (1:2-1:4, grams to milliliter) as independent variables. A maximum xylose concentration of 50 g/L was obtained in the hemicellulosic hydrolysate. The fermentation of hemicellulosic hydrolysate and the SSF process were performed in bioreactors and the final ethanol concentrations of 15.3 g/L and 28.7 g/L were obtained, respectively.

  15. Ethanol production from Sorghum bicolor using both separate and simultaneous saccharification and fermentation in batch and fed batch systems

    DEFF Research Database (Denmark)

    Mehmood, Sajid; Gulfraz, M.; Rana, N. F.;


    The objective of this work was to find the best combination of different experimental conditions during pre-treatment, enzymatic saccharification, detoxification of inhibitors and fermentation of Sorghum bicolor straw for ethanol production. The optimization of pre-treatment using different...

  16. Sustainable Ethanol Production from Common Reed (Phragmites australis through Simultaneuos Saccharification and Fermentation

    Directory of Open Access Journals (Sweden)

    Franco Cotana


    Full Text Available Phragmites australis (common reed is a perennial grass that grows in wetlands or near inland waterways. Due to its fast-growing properties and low requirement in nutrients and water, this arboreal variety is recognized as a promising source of renewable energy although it is one of the least characterized energy crops. In this experiment, the optimization of the bioethanol production process from Phragmites australis was carried out. Raw material was first characterized according to the standard procedure (NREL to evaluate its composition in terms of cellulose, hemicellulose, and lignin content. Common reed was pretreated by steam explosion process at three different severity factor (R0 values. The pretreatment was performed in order to reduce biomass recalcitrance and to make cellulose more accessible to enzymatic attack. After the pretreatment, a water insoluble substrate (WIS rich in cellulose and lignin and a liquid fraction rich in pentose sugars (xylose and arabinose and inhibitors were collected and analyzed. The simultaneous saccharification and fermentation (SSF of the WIS was performed at three different solid loadings (SL 10%, 15%, 20% (w/w. The same enzyme dosage, equal to 20% (g enzyme/g cellulose, was used for all the WIS loadings. The efficiency of the whole process was evaluated in terms of ethanol overall yield (g ethanol/100 g raw material. The maximum ethanol overall yields achieved were 16.56 and 15.80 g ethanol/100 g RM dry basis for sample AP10 and sample AP4.4, respectively. The yields were reached working at lower solid loading (10% and at the intermediate LogR0 value for the former and at intermediate solid loading (15% and high LogR0 value for the latter, respectively.

  17. Ethanol production by Mucor indicus and Rhizopus oryzae from rice straw by separate hydrolysis and fermentation

    Energy Technology Data Exchange (ETDEWEB)

    Abedinifar, Sorahi [Department of Chemical Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran); Karimi, Keikhosro [Department of Chemical Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran); School of Engineering, University of Boraas, SE-501 90 Boraas (Sweden); Khanahmadi, Morteza [Isfahan Agriculture and Natural Resources Research Centre, Isfahan (Iran); Taherzadeh, Mohammad J. [School of Engineering, University of Boraas, SE-501 90 Boraas (Sweden)


    Rice straw was successfully converted to ethanol by separate enzymatic hydrolysis and fermentation by Mucor indicus, Rhizopus oryzae, and Saccharomyces cerevisiae. The hydrolysis temperature and pH of commercial cellulase and {beta}-glucosidase enzymes were first investigated and their best performance obtained at 45 C and pH 5.0. The pretreatment of the straw with dilute-acid hydrolysis resulted in 0.72 g g{sup -1} sugar yield during 48 h enzymatic hydrolysis, which was higher than steam-pretreated (0.60 g g{sup -1}) and untreated straw (0.46 g g{sup -1}). Furthermore, increasing the concentration of the dilute-acid pretreated straw from 20 to 50 and 100 g L{sup -1} resulted in 13% and 16% lower sugar yield, respectively. Anaerobic cultivation of the hydrolyzates with M. indicus resulted in 0.36-0.43 g g{sup -1} ethanol, 0.11-0.17 g g{sup -1} biomass, and 0.04-0.06 g g{sup -1} glycerol, which is comparable with the corresponding yields by S. cerevisiae (0.37-0.45 g g{sup -1} ethanol, 0.04-0.10 g g{sup -1} biomass and 0.05-0.07 glycerol). These two fungi produced no other major metabolite from the straw and completed the cultivation in less than 25 h. However, R. oryzae produced lactic acid as the major by-product with yield of 0.05-0.09 g g{sup -1}. This fungus had ethanol, biomass and glycerol yields of 0.33-0.41, 0.06-0.12, and 0.03-0.04 g g{sup -1}, respectively. (author)

  18. Combined inactivation of the Clostridium cellulolyticum lactate and malate dehydrogenase genes substantially increases ethanol yield from cellulose and switchgrass fermentations

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yongchao [ORNL; Tschaplinski, Timothy J [ORNL; Engle, Nancy L [ORNL; Hamilton, Choo Yieng [ORNL; Rodriguez, Jr., Miguel [ORNL; Liao, James C [ORNL; Schadt, Christopher Warren [ORNL; Guss, Adam M [ORNL; Yang, Yunfeng [ORNL; Graham, David E [ORNL


    Background: The model bacterium Clostridium cellulolyticum efficiently hydrolyzes crystalline cellulose and hemicellulose, using cellulosomes to degrade lignocellulosic biomass. Although it imports and ferments both pentose and hexose sugars to produce a mixture of ethanol, acetate, lactate, H2 and CO2, the proportion of ethanol is low, which impedes its use in consolidated bioprocessing for biofuels. Therefore genetic engineering will likely be required to improve the ethanol yield. Random mutagenesis, plasmid transformation, and heterologous expression systems have previously been developed for C. cellulolyticum, but targeted mutagenesis has not been reported for this organism. Results: The first targeted gene inactivation system was developed for C. cellulolyticum, based on a mobile group II intron originating from the Lactococcus lactis L1.LtrB intron. This markerless mutagenesis system was used to disrupt both the paralogous L-lactate dehydrogenase (Ccel_2485; ldh) and L-malate dehydrogenase (Ccel_0137; mdh) genes, distinguishing the overlapping substrate specificities of these enzymes. Both mutations were then combined in a single strain. This double mutant produced 8.5-times more ethanol than wild-type cells growing on crystalline cellulose. Ethanol constituted 93% of the major fermentation products (by molarity), corresponding to a molar ratio of ethanol to organic acids of 15, versus 0.18 in wild-type cells. During growth on acid-pretreated switchgrass, the double mutant also produced four-times as much ethanol as wild-type cells. Detailed metabolomic analyses identified increased flux through the oxidative branch of the mutant s TCA pathway. Conclusions: The efficient intron-based gene inactivation system produced the first gene-targeted mutations in C. cellulolyticum. As a key component of the genetic toolbox for this bacterium, markerless targeted mutagenesis enables functional genomic research in C. cellulolyticum and rapid genetic engineering to

  19. Selection of a thermotolerant Kluyveromyces marxianus strain with potential application for cellulosic ethanol production by simultaneous saccharification and fermentation. (United States)

    Castro, Rafael Cunha A; Roberto, Inês C


    The development of technologies for cellulosic ethanol production by simultaneous saccharification and fermentation (SSF) depends on the use of microorganisms with high fermentative rates and thermotolerance. In this study, the ability of five Kluyveromyces marxianus strains to produce ethanol from glucose at 45 °C was investigated. The highest fermentative parameters were observed with K. marxianus NRRL Y-6860, which was then further studied. An initial evaluation of the oxygen supply on ethanol production by the selected yeast and a comparison of SSF process from acid pretreated rice straw between K. marxianus NRRL Y-6860 and Saccharomyces cerevisiae at 30 and 45 °C were carried out. Under the lowest evaluated conditions of aeration and agitation, K. marxianus NRRL Y-6860 produced 21.5 g/L ethanol from 51.3 g/L glucose corresponding to YP/S of 0.44 g/g and QP of 3.63 g/L h. In the SSF experiments, K. marxianus NRRL Y-6860 was more efficient than S. cerevisiae at both evaluated temperatures (30 and 45 °C), attained at the highest temperature an ethanol yield of 0.24 g/g and productivity of 1.44 g/L h.

  20. Acetone-butanol-ethanol (ABE) fermentation in an immobilized cell trickle bed reactor. (United States)

    Park, C H; Okos, M R; Wankat, P C


    Acetone-butanol-ethanol (ABE) fermentation was successfully carried out in an immobilized cell trickle bed reactor. The reactor was composed of two serial columns packed with Clostridium acetobutylicum ATCC 824 entrapped on the surface of natural sponge segments at a cell loading in the range of 2.03-5.56 g dry cells/g sponge. The average cell loading was 3.58 g dry cells/g sponge. Batch experiments indicated that a critical pH above 4.2 is necessary for the initiation of cell growth. One of the media used during continuous experiments consisted of a salt mixture alone and the other a nutrient medium containing a salt mixture with yeast extract and peptone. Effluent pH was controlled by supplying various fractions of the two different types of media. A nutrient medium fraction above 0.6 was crucial for successful fermentation in a trickle bed reactor. The nutrient medium fraction is the ratio of the volume of the nutrient medium to the total volume of nutrient plus salt medium. Supplying nutrient medium to both columns continuously was an effective way to meet both pH and nutrient requirement. A 257-mL reactor could ferment 45 g/L glucose from an initial concentration of 60 g/L glucose at a rate of 70 mL/h. Butanol, acetone, and ethanol concentrations were 8.82, 5.22, and 1.45 g/L, respectively, with a butanol and total solvent yield of 19.4 and 34.1 wt %. Solvent productivity in an immobilized cell trickle bed reactor was 4.2 g/L h, which was 10 times higher than that obtained in a batch fermentation using free cells and 2.76 times higher than that of an immobilized CSTR. If the nutrient medium fraction was below 0.6 and the pH was below 4.2, the system degenerated. Oxygen also contributed to the system degeneration. Upon degeneration, glucose consumption and solvent yield decreased to 30.9 g/L and 23.0 wt %, respectively. The yield of total liquid product (40.0 wt %) and butanol selectivity (60.0 wt %) remained almost constant. Once the cells were degenerated

  1. Enhanced ethanol and glucosamine production from rice husk by NAOH pretreatment and fermentation by fungus Mucor hiemalis

    Directory of Open Access Journals (Sweden)

    Maryam Omidvar


    Full Text Available Ethanol production from rice husk by simultaneous saccharification and fermentation using Mucor hiemalis was investigated. To reach the maximum ethanol production yield, the most important influencing factors in the pretreatment process, including temperature (0-100°C, NaOH concentration (1-3 M, and the pretreatment time (30-180 min, were optimized using an experimental design by a response surface methodology (RSM. The maximum ethanol production yield of 86.7 % was obtained after fungal cultivation on the husk pretreated with 2.6 M NaOH at 67°C for 150 min. This was higher than the yield of 57.7% obtained using Saccharomyces cerevisiae as control. Furthermore, fermentation using M. hiemalis under the optimum conditions led to the production of a highly valuable fungal biomass, containing 60 g glucosamine (GlcN, 410 g protein, and 160 g fungal oil per each kg of the fungal biomass.

  2. Ethanol production from sorghum grains [Sorghum bicolor (L. Moench]: evaluation of the enzymatic hydrolysis and the hydrolysate fermentability

    Directory of Open Access Journals (Sweden)

    C. A. Barcelos


    Full Text Available The production of ethanol from sorghum grains was investigated in the present work. Initially, starch enzymatic hydrolysis was investigated using commercial α-amylase and glucoamylase, considering particle size, solid:liquid ratio and enzyme load as variables. The hydrolysate, in the best conditions (73 U of α-amylase/g grain and 1150 U glucoamylase/g grain, contained glucose at a concentration of approximately 250 g/L, which was fermented to produce ethanol in a bioreactor in batch mode. Using an industrial strain of Saccharomyces cerevisiae, the maximum ethanol concentration produced was roughly 106 g.L-1 in 24 h of fermentation, resulting in a volumetric productivity of 4.4 g.L-1.h-1 and a product yield based on the substrate consumed (0.499 g.g-1 close to the theoretical.

  3. Mathematical modeling of continuous ethanol fermentation in a membrane bioreactor by pervaporation compared to conventional system: Genetic algorithm. (United States)

    Esfahanian, Mehri; Shokuhi Rad, Ali; Khoshhal, Saeed; Najafpour, Ghasem; Asghari, Behnam


    In this paper, genetic algorithm was used to investigate mathematical modeling of ethanol fermentation in a continuous conventional bioreactor (CCBR) and a continuous membrane bioreactor (CMBR) by ethanol permselective polydimethylsiloxane (PDMS) membrane. A lab scale CMBR with medium glucose concentration of 100gL(-1) and Saccharomyces cerevisiae microorganism was designed and fabricated. At dilution rate of 0.14h(-1), maximum specific cell growth rate and productivity of 0.27h(-1) and 6.49gL(-1)h(-1) were respectively found in CMBR. However, at very high dilution rate, the performance of CMBR was quite similar to conventional fermentation on account of insufficient incubation time. In both systems, genetic algorithm modeling of cell growth, ethanol production and glucose concentration were conducted based on Monod and Moser kinetic models during each retention time at unsteady condition. The results showed that Moser kinetic model was more satisfactory and desirable than Monod model.

  4. Techno-economic analysis of corn stover fungal fermentation to ethanol

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, Pimphan; Tews, Iva J.; Magnuson, Jon K.; Karagiosis, Sue A.; Jones, Susanne B.


    This techno-economic analysis assesses the process economics of ethanol production from lignocellulosic feedstock by fungi in order to identify promising opportunities and the research needed to achieve them. Based on literature derived data, four different ethanologen strains are considered in this study: native and recombinant Saccharomyces cerevisiae, the natural pentose-fermenting yeast, Pichia stipitis and the filamentous fungus Fusarium oxysporum. Organism performance and technology readiness are split into three groups: near-term (<5 years), mid-term (5-10 years) and long-term (>10 years) process deployment. Processes classified as near-term could reasonably be developed in this shorter time frame, as suggested by recent literature. Mid-term technology process models are based on lab-scale experimental data, and yields near the theoretical limit are used to estimate long-term technology goals. Further research and economic evaluation on the integrated production of chemicals and fuels in biorefineries are recommended.

  5. Long term storage of dilute acid pretreated corn stover feedstock and ethanol fermentability evaluation. (United States)

    Zhang, Jian; Shao, Shuai; Bao, Jie


    This study reported a new solution of lignocellulose feedstock storage based on the distributed pretreatment concept. The dry dilute sulfuric acid pretreatment (DDAP) was conducted on corn stover feedstock, instead of ammonia fiber explosion pretreatment. Then the dry dilute acid pretreated corn stover was stored for three months during summer season with high temperature and humidity. No negative aspects were found on the physical property, composition, hydrolysis yield and ethanol fermentability of the long term stored pretreated corn stover, plus the additional merits including no chemicals recovery operation, anti-microbial contaminant environment from stronger acid and inhibitor contents, as well as the mild and slow hydrolysis in the storage. The new pretreatment method expanded the distributed pretreatment concept of feedstock storage with potential for practical application.

  6. Production of acetone-butanol-ethanol (ABE) in direct fermentation of cassava by Clostridium saccharoperbutylacetonicum N1-4. (United States)

    Thang, Vu Hong; Kanda, Kohzo; Kobayashi, Genta


    In this work, acetone-butanol-ethanol (ABE) fermentation characteristics of cassava starch and cassava chips when using Clostridium saccharoperbutylacetonicum N1-4 was presented. The obtained results in batch mode using a 1-L fermenter showed that C. saccharoperbutylacetonicum N1-4 was a hyperamylolytic strain and capable of producing solvents efficiently from cassava starch and cassava chips, which was comparable to when glucose was used. Batch fermentation of cassava starch and cassava chips resulted in 21.0 and 19.4 g/L of total solvent as compared with 24.2 g/L of total solvent when using glucose. Solvent productivity in fermentation of cassava starch was from 42% to 63% higher than that obtained in fermentation using corn and sago starches in the same condition. In fermentation of cassava starch and cassava chips, maximum butanol concentration was 16.9 and 15.5 g/L, respectively. Solvent yield and butanol yield (based on potential glucose) was 0.33 and 0.41, respectively, for fermentation of cassava starch and 0.30 and 0.38, respectively for fermentation using cassava chips.

  7. Ethanol Production from Non-Food Tubers of Iles-iles (Amorphophallus campanulatus by Using Separated Hydrolysis and Fermentation

    Directory of Open Access Journals (Sweden)

    Kusmiyati Kusmiyati


    Full Text Available The decrease in production and the raise in needs have led to the rise in oil prices. This work investigated the possibility of Iles-iles (Amorphophallus campanulatus tuber flour, which is rich in carbohydrate con-tent, as a raw material to produce bioethanol. To obtain the maximum ethanol concentration, several parameters had been studied, such as: the concentration of α-amylase and β-amylase in liquefaction and sac-charification processes, respectively, the type of S. cerevisiae enzyme (pure, dry, wet and instant and weight of Diammonium phosphate (DAP as a nutrient for S. cerevisiae in fermentation. The result shows that the highest reducing sugar content (12.5% was achieved when 3.2 ml α-amylase/kg flour and 6.4 ml β-amylase/kg flour were used during liquefaction and saccharification processes. Since the concentration of α- and β-amylase increased, the reducing sugar obtained also increased. The higher sugar content resulted the higher the ethanol concentration in the fermentation broth. Furthermore, the highest concentration of ethanol (9 %v/v was obtained at 72 h fermentation using the dry S. cerevisiae, at 3.2 ml and 6.4 ml /kg flour of α-amylase and β-amylase enzymes, respectively. From the study of the effect of S. cerevisiae type, it was shown that dry S. cereviseae produced the highest ethanol concentration 10.2% (v/v at 72 h fermentation. The DAP was used as a nitrogen supply required by S. cerevisiae to growth and as a results can increase the ethanol concentration. The addition of DAP in the fermentation proved that 8.45% (v/v of ethanol was obtained. This result shows that the proposed tuber flour has the potential a raw material for bioethanol production. © 2014 BCREC UNDIP. All rights reservedReceived: 7th January 2014; Revised: 10th March 2014; Accepted: 18th March 2014[How to Cite: Kusmiyati, K. (2014. Ethanol Production from Non-Food Tubers of Iles-iles (Amorphophallus campanulatus by using Separated Hydrolysis and

  8. Acetone-butanol-ethanol fermentation of corn stover: current production methods, economic viability and commercial use. (United States)

    Baral, Nawa R; Slutzky, Lauren; Shah, Ajay; Ezeji, Thaddeus C; Cornish, Katrina; Christy, Ann


    Biobutanol is a next-generation liquid biofuel with properties akin to those of gasoline. There is a widespread effort to commercialize biobutanol production from agricultural residues, such as corn stover, which do not compete with human and animal foods. This pursuit is backed by extensive government mandates to expand alternative energy sources. This review provides an overview of research on biobutanol production using corn stover feedstock. Structural composition, pretreatment, sugar yield (following pretreatment and hydrolysis) and generation of lignocellulose-derived microbial inhibitory compounds (LDMICs) from corn stover are discussed. The review also discusses different Clostridium species and strains employed for biobutanol production from corn stover-derived sugars with respect to solvent yields, tolerance to LDMICs and in situ solvent recovery (integrated fermentation). Further, the economics of cellulosic biobutanol production are highlighted and compared to corn starch-derived ethanol and gasoline. As discussed herein, the economic competitiveness of biobutanol production from corn stover largely depends on feedstock processing and fermentation process design.

  9. Metabolic engineering of Clostridium acetobutylicum ATCC 824 for isopropanol-butanol-ethanol fermentation. (United States)

    Lee, Joungmin; Jang, Yu-Sin; Choi, Sung Jun; Im, Jung Ae; Song, Hyohak; Cho, Jung Hee; Seung, Do Young; Papoutsakis, E Terry; Bennett, George N; Lee, Sang Yup


    Clostridium acetobutylicum naturally produces acetone as well as butanol and ethanol. Since acetone cannot be used as a biofuel, its production needs to be minimized or suppressed by cell or bioreactor engineering. Thus, there have been attempts to disrupt or inactivate the acetone formation pathway. Here we present another approach, namely, converting acetone to isopropanol by metabolic engineering. Since isopropanol can be used as a fuel additive, the mixture of isopropanol, butanol, and ethanol (IBE) produced by engineered C. acetobutylicum can be directly used as a biofuel. IBE production is achieved by the expression of a primary/secondary alcohol dehydrogenase gene from Clostridium beijerinckii NRRL B-593 (i.e., adh(B-593)) in C. acetobutylicum ATCC 824. To increase the total alcohol titer, a synthetic acetone operon (act operon; adc-ctfA-ctfB) was constructed and expressed to increase the flux toward isopropanol formation. When this engineering strategy was applied to the PJC4BK strain lacking in the buk gene (encoding butyrate kinase), a significantly higher titer and yield of IBE could be achieved. The resulting PJC4BK(pIPA3-Cm2) strain produced 20.4 g/liter of total alcohol. Fermentation could be prolonged by in situ removal of solvents by gas stripping, and 35.6 g/liter of the IBE mixture could be produced in 45 h.

  10. PDMS复合膜从发酵液中渗透汽化回收乙醇%Ethanol Recovery from Fermentation Broth by Pervaporation Using a Composite polydimethylsiloxane Membrane

    Institute of Scientific and Technical Information of China (English)

    伍勇; 黄卫星; 肖泽仪; 钟月华


    The pervaporation behavior of fermentation broth was investigated experimentally and compared with those started with ethanol mixtures. Ethanol was produced by Saccharomyces cerevisiae utilizing technical grade glucose and recovered by pervaporation using a composite polydimethylsiloxane (PDMS) membrane prepared in our laboratory. Ethanol concentration in fermentation broth decreased to a relatively low level when pervaporation was coupled with fermentation. The more active cells appeared in the fermentation broth, the better the membrane performance was.

  11. The transcription factor Ace2 and its paralog Swi5 regulate ethanol production during static fermentation through their targets Cts1 and Rps4a in Saccharomyces cerevisiae. (United States)

    Wu, Yao; Du, Jie; Xu, Guoqiang; Jiang, Linghuo


    Saccharomyces cerevisiae is the most widely used fermentation organism for ethanol production. However, the gene expression regulatory networks behind the ethanol fermentation are still not fully understood. Using a static fermentation model, we examined the ethanol yields on biomass of deletion mutants for 77 yeast genes encoding nonessential transcription factors, and found that deletion mutants for ACE2 and SWI5 showed dramatically increased ethanol yields. Overexpression of ACE2 or SWI5 in wild type cells reduced their ethanol yields. Furthermore, among the 34 target genes regulated by Ace2 and Swi5, deletion of CTS1,RPS4a,SIC1,EGT2,DSE2, or SCP160 led to increased ethanol yields, with the former two showing higher effects. Overexpression of CTS1 or RPS4a in both ace2/ace2 and swi5/swi5 mutants reduced their ethanol yields. In contrast, deletion of MCR1 or HO significantly decreased ethanol yields, with the former one showing the highest effect. Therefore, Ace2 and Swi5 are two negative regulators of ethanol yield during static fermentation of yeast cells, and both CTS1 and RPS4a are major effectors mediating these two transcription factors in regulating ethanol production.

  12. Combined inactivation of the Clostridium cellulolyticum lactate and malate dehydrogenase genes substantially increases ethanol yield from cellulose and switchgrass fermentations

    Directory of Open Access Journals (Sweden)

    Li Yongchao


    Full Text Available Abstract Background The model bacterium Clostridium cellulolyticum efficiently degrades crystalline cellulose and hemicellulose, using cellulosomes to degrade lignocellulosic biomass. Although it imports and ferments both pentose and hexose sugars to produce a mixture of ethanol, acetate, lactate, H2 and CO2, the proportion of ethanol is low, which impedes its use in consolidated bioprocessing for biofuels production. Therefore genetic engineering will likely be required to improve the ethanol yield. Plasmid transformation, random mutagenesis and heterologous expression systems have previously been developed for C. cellulolyticum, but targeted mutagenesis has not been reported for this organism, hindering genetic engineering. Results The first targeted gene inactivation system was developed for C. cellulolyticum, based on a mobile group II intron originating from the Lactococcus lactis L1.LtrB intron. This markerless mutagenesis system was used to disrupt both the paralogous L-lactate dehydrogenase (Ccel_2485; ldh and L-malate dehydrogenase (Ccel_0137; mdh genes, distinguishing the overlapping substrate specificities of these enzymes. Both mutations were then combined in a single strain, resulting in a substantial shift in fermentation toward ethanol production. This double mutant produced 8.5-times more ethanol than wild-type cells growing on crystalline cellulose. Ethanol constituted 93% of the major fermentation products, corresponding to a molar ratio of ethanol to organic acids of 15, versus 0.18 in wild-type cells. During growth on acid-pretreated switchgrass, the double mutant also produced four times as much ethanol as wild-type cells. Detailed metabolomic analyses identified increased flux through the oxidative branch of the mutant's tricarboxylic acid pathway. Conclusions The efficient intron-based gene inactivation system produced the first non-random, targeted mutations in C. cellulolyticum. As a key component of the genetic toolbox

  13. Fermentation of lactose to bio-ethanol by yeasts as part of integrated solutions for the valorisation of cheese whey. (United States)

    Guimarães, Pedro M R; Teixeira, José A; Domingues, Lucília


    Cheese whey, the main dairy by-product, is increasingly recognized as a source of many bioactive valuable compounds. Nevertheless, the most abundant component in whey is lactose (ca. 5% w/v), which represents a significant environmental problem. Due to the large lactose surplus generated, its conversion to bio-ethanol has long been considered as a possible solution for whey bioremediation. In this review, fermentation of lactose to ethanol is discussed, focusing on wild lactose-fermenting yeasts, particularly Kluyveromyces marxianus, and recombinant Saccharomyces cerevisiae strains. The early efforts in the screening and characterization of the fermentation properties of wild lactose-consuming yeasts are reviewed. Furthermore, emphasis is given on the latter advances in engineering S. cerevisiae strains for efficient whey-to-ethanol bioprocesses. Examples of industrial implementation are briefly discussed, illustrating the viability of whey-to-ethanol systems. Current developments on strain engineering together with the growing market for biofuels will likely boost the industrial interest in such processes.

  14. Nitrogen fertilization affects corn cellulosic biomass and ethanol yields (United States)

    Research results on the effects of N management on corn (Zea mays L.) grain production in high-yielding cropping systems are widely available, but information on its effects on cellulosic ethanol potential from corn stover and cobs is limited. Stover and cob biomass and respective ethanol yields all...

  15. Ethanol fermentation by the thermotolerant yeast, Kluyveromyces marxianus TISTR5925, of extracted sap from old oil palm trunk

    Directory of Open Access Journals (Sweden)

    Yoshinori Murata


    Full Text Available Palm sap extracted from old oil palm trunks was previously found to contain sugar and nutrients (amino acids and vitamins. Some palm saps contain a low content of sugar due to differences in species or in plant physiology. Here we condensed palm sap with a low content of sugar using flat membrane filtration, then fermented the condensed palm sap at high temperature using the thermotolerant, high ethanol-producing yeast, Kluyveromyces marxianus. Ethanol production under non-optimum conditions was evaluated. Furthermore, the energy required to concentrate the palm sap, and the amount of energy that could be generated from the ethanol, was calculated. The condensation of sugar in sap from palm trunk required for economically viable ethanol production was evaluated.

  16. Comparative technoeconomic analysis of a softwood ethanol process featuring posthydrolysis sugars concentration operations and continuous fermentation with cell recycle. (United States)

    Schneiderman, Steven J; Gurram, Raghu N; Menkhaus, Todd J; Gilcrease, Patrick C


    Economical production of second generation ethanol from Ponderosa pine is of interest due to widespread mountain pine beetle infestation in the western United States and Canada. The conversion process is limited by low glucose and high inhibitor concentrations resulting from conventional low-solids dilute acid pretreatment and enzymatic hydrolysis. Inhibited fermentations require larger fermentors (due to reduced volumetric productivity) and low sugars lead to low ethanol titers, increasing distillation costs. In this work, multiple effect evaporation (MEE) and nanofiltration (NF) were evaluated to concentrate the hydrolysate from 30 g/l to 100, 150, or 200 g/l glucose. To ferment this high gravity, inhibitor containing stream, traditional batch fermentation was compared with continuous stirred tank fermentation (CSTF) and continuous fermentation with cell recycle (CSTF-CR). Equivalent annual operating cost (EAOC = amortized capital + yearly operating expenses) was used to compare these potential improvements for a local-scale 5 MGY ethanol production facility. Hydrolysate concentration via evaporation increased EAOC over the base process due to the capital and energy intensive nature of evaporating a very dilute sugar stream; however, concentration via NF decreased EAOC for several of the cases (by 2 to 15%). NF concentration to 100 g/l glucose with a CSTF-CR was the most economical option, reducing EAOC by $0.15 per gallon ethanol produced. Sensitivity analyses on NF options showed that EAOC improvement over the base case could still be realized for even higher solids removal requirements (up to two times higher centrifuge requirement for the best case) or decreased NF performance.

  17. Recovery of Acetic Acid from An Ethanol Fermentation Broth by Liquid-Liquid Extraction (LLE) Using Various Solvents

    Energy Technology Data Exchange (ETDEWEB)

    Pham, Thi Thu Huong; Kim, Tae Hyun [Kongju National University, Cheonan (Korea, Republic of); Um, Byung Hwan [Hankyong National University, Anseong (Korea, Republic of)


    Liquid-liquid extraction (LLE) using various solvents was studied for recovery of acetic acid from a synthetic ethanol fermentation broth. The microbial fermentation of sugars presented in hydrolyzate gives rise to acetic acid as a byproduct. In order to obtain pure ethanol for use as a biofuel, fermentation broth should be subjected to acetic acid removal step and the recovered acetic acid can be put to industrial use. Herein, batch LLE experiments were carried out at 25°C using a synthetic fermentation broth comprising 20.0 g l{sup -1} acetic acid and 5.0 g l{sup -1} ethanol. Ethyl acetate (EtOAc), tri-n-octylphosphine oxide (TOPO), tri-n-octylamine (TOA), and tri-n-alkylphosphine oxide (TAPO) were utilized as solvents, and the extraction potential of each solvent was evaluated by varying the organic phase-to-aqueous phase ratios as 0.2, 0.5, 1.0, 2.0, and 4.0. The highest acetic acid extraction yield was achieved with TAPO; however, the lowest ethanol-to-acetic acid extraction ratio was obtained using TOPO. In a single-stage batch extraction, 97.0 % and 92.4 % of acetic acid could be extracted using TAPO and TOPO when the ratio of organic-to-aqueous phases is 4:1 respectively. A higher solvent-to-feed ratio resulted in an increase in the ethanol-to-acetic acid ratio, which decreased both acetic acid purity and acetic acid extraction yield.

  18. Performance and energy metabolism in restrictively fed weanling pigs are not affected by feeding either fermented cereals or their end-products. (United States)

    Bruininx, E M A M; Binnendijk, G P; Zandstra, T; Heetkamp, M J W; Van Der Peet-Schwering, C M C; Gerrits, W J J


    To study the effects of feeding fermented cereals or just fermentation end-products on performance and energy metabolism, 18 restrictedly fed groups of eight pigs each were assigned to one of three dietary treatments: (i) a liquid control diet (C) containing 40% of a mixture of barley and wheat; or (ii) a liquid diet (F) containing 40% fermented barley and wheat; or (iii) a liquid diet as C with the addition of some important fermentation end-products (FP; organic acids and ethanol) in concentrations similar to those in the fermented F-diet. Energy and nitrogen balances, heat production, and performance traits were measured during two consecutive periods (days 1-5 and days 6-14). There was a considerable increase in average dry matter intake that tended (p = 0.06) to be higher in the FP-group than in the other groups. Apparent fecal digestibility of dry matter, ash, nitrogen and energy during period 2 were not affected (p > 0.1). Averaged over both periods, none of the energy metabolism parameters were affected by the diets (p > 0.1). However, there were diet × period interactions for metabolizable energy-intake (p = 0.07), energy retention (p feeding of either 40% fermented cereals nor their fermentation end-products affected performance and energy metabolism traits in weanling pigs. Nevertheless, lower postprandial activity-related heat production by pigs given the fermented cereals suggest a stimulating effect of fermented cereals on short term satiety that was not seen in pigs given fermentation end-products only.

  19. A novel wild-type Saccharomyces cerevisiae strain TSH1 in scaling-up of solid-state fermentation of ethanol from sweet sorghum stalks.

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    Ran Du

    Full Text Available The rising demand for bioethanol, the most common alternative to petroleum-derived fuel used worldwide, has encouraged a feedstock shift to non-food crops to reduce the competition for resources between food and energy production. Sweet sorghum has become one of the most promising non-food energy crops because of its high output and strong adaptive ability. However, the means by which sweet sorghum stalks can be cost-effectively utilized for ethanol fermentation in large-scale industrial production and commercialization remains unclear. In this study, we identified a novel Saccharomyces cerevisiae strain, TSH1, from the soil in which sweet sorghum stalks were stored. This strain exhibited excellent ethanol fermentative capacity and ability to withstand stressful solid-state fermentation conditions. Furthermore, we gradually scaled up from a 500-mL flask to a 127-m3 rotary-drum fermenter and eventually constructed a 550-m3 rotary-drum fermentation system to establish an efficient industrial fermentation platform based on TSH1. The batch fermentations were completed in less than 20 hours, with up to 96 tons of crushed sweet sorghum stalks in the 550-m3 fermenter reaching 88% of relative theoretical ethanol yield (RTEY. These results collectively demonstrate that ethanol solid-state fermentation technology can be a highly efficient and low-cost solution for utilizing sweet sorghum, providing a feasible and economical means of developing non-food bioethanol.

  20. Ethanol production via in situ fungal saccharification and fermentation of mild alkali and steam pretreated corn fiber. (United States)

    Shrestha, Prachand; Khanal, Samir Kumar; Pometto, Anthony L; Hans van Leeuwen, J


    The effect of mild alkali and steam pretreatments on fungal saccharification and sequential simultaneous-saccharification and fermentation (SSF) of corn fiber to ethanol was studied. The corn fiber was pretreated with: (i) 2% NaOH (w/w) at 30 degrees C for 2h and (ii) steaming at 100 degrees C for 2h. Ethanol yields were 2.6g, 2.9g and 5.5g ethanol/100g of corn fiber, respectively, for Phanerochaete chrysosporium, Gloeophyllum trabeum and Trichoderma reesei saccharification and sequential SSFs. SSF with commercial cellulase enzyme - Spezyme-CP had 7.7g ethanol/100g corn fiber. Mild alkali pretreatment resulted in higher glucose yields following fungal saccharification of corn fiber. However, the ethanol yields were comparatively similar for untreated and mild alkali pretreated corn fiber. Solid-substrate fermentation of corn fiber with fungi can be improved to either eliminate or reduce the dosage of commercial cellulase enzymes during SSF.

  1. Kinetic and Energetic Parameters of Carob Wastes Fermentation by Saccharomyces cerevisiae: Crabtree Effect, Ethanol Toxicity, and Invertase Repression. (United States)

    Rodrigues, B; Peinado, J M; Raposo, S; Constantino, A; Quintas, C; Lima-Costa, M E


    Carob waste is a useful raw material for the second-generation ethanol because 50% of its dry weight is sucrose, glucose, and fructose. To optimize the process, we have studied the influence of the initial concentration of sugars on the fermentation performance of Saccharomyces cerevisiae. With initial sugar concentrations (S0) of 20 g/l, the yeasts were derepressed and the ethanol produced during the exponential phase was consumed in a diauxic phase. The rate of ethanol consumption decreased with increasing S0 and disappeared at 250 g/l when the Crabtree effect was complete and almost all the sugar consumed was transformed into ethanol with a yield factor of 0.42 g/g. Sucrose hydrolysis was delayed at high S0 because of glucose repression of invertase synthesis, which was triggered at concentrations above 40 g/l. At S0 higher than 250 g/l, even when glucose had been exhausted, sucrose was hydrolyzed very slowly, probably due to an inhibition at this low water activity. Although with lower metabolic rates and longer times of fermentation, 250 g/l is considered the optimal initial concentration because it avoids the diauxic consumption of ethanol and maintains enough invertase activity to consume all the sucrose, and also avoids the inhibitions due to lower water activities at higher S0.

  2. Factors affecting release of ethanol vapour in active modified atmosphere packaging systems for horticultural products

    Directory of Open Access Journals (Sweden)

    Weerawate Utto


    Full Text Available The active modified atmosphere packaging (active MAP system , which provides interactive postharvest control , using ethanol vapour controlled release, is one of the current interests in the development of active packaging for horticultural products. A number of published research work have discussed the relationship between the effectiveness of ethanol vapour and its concentration in the package headspace, including its effect on postharvest decay and physiological controls. This is of importance because a controlled release system should release and maintain ethanol vapour at effective concentrations during the desired storage period. A balance among the mass transfer processes of ethanol vapour in the package results in ethanol vapour accumulation in the package headspace. Key factors affecting these processes include ethanol loading, packaging material, packaged product and storage environment (temperature and relative h umidity. This article reviews their influences and discusses future work required to better understand their influences on ethanol vapour release and accumulations in active MAP.

  3. Direct Ethanol Production from Breadfruit Starch (Artocarpus communis Forst. by Engineered Simultaneous Saccharification and Fermentation (ESSF using Microbes Consortium

    Directory of Open Access Journals (Sweden)

    Iftachul Farida


    Full Text Available Breadfruit (Artocarpus communis Forst. is one of sources for ethanol production, which has high starch content (89%. Ethanol production from breadfruit starch was conducted by Simultaneous Saccharification and Fermentation (SSF technology using microbes consortium. The aim of the research was to examine a method to produce ethanol by SSF technology using microbes consortium at high yield and efficiency. The main research consisted of two treatments, namely normal SSF and enginereed SSF. The results showed that normal SSF using aeration and agitation during cultivation could produce ethanol at 11.15 ± 0.18 g/L, with the yield of product (Yp/s 0.34 g ethanol/g substrate; and yield of biomass (Yx/s 0.29 g cell/g substrate, respectively. A better result was obtained using engineered SSF in which aeration was stopped after biomass condition has reached the end of the exponential phase. The ethanol produced was 12.75 ± 0.04 g/L, with the yields of product (Yp/s 0.41 g ethanol/g substrate, and the yield of cell (Yx/s 0.09 g cell/g substrate.

  4. Alleviation of harmful effect in stillage reflux in food waste ethanol fermentation based on metabolic and side-product accumulation regulation. (United States)

    Ma, Hongzhi; Yang, Jian; Jia, Yan; Wang, Qunhui; Ma, Xiaoyu; Sonomoto, Kenji


    Stillage reflux fermentation in food waste ethanol fermentation could reduce sewage discharge but exert a harmful effect because of side-product accumulation. In this study, regulation methods based on metabolic regulation and side-product alleviation were conducted. Result demonstrated that controlling the proper oxidation-reduction potential value (-150mV to -250mV) could reduce the harmful effect, improve ethanol yield by 21%, and reduce fermentation time by 20%. The methods of adding calcium carbonate to adjust the accumulated lactic acid showed that ethanol yield increased by 17.3%, and fermentation time decreased by 20%. The accumulated glyceal also shows that these two methods can reduce the harmful effect. Fermentation time lasted for seven times without effect, and metabolic regulation had a better effect than side-product regulation.

  5. NREL 2012 Achievement of Ethanol Cost Targets: Biochemical Ethanol Fermentation via Dilute-Acid Pretreatment and Enzymatic Hydrolysis of Corn Stover

    Energy Technology Data Exchange (ETDEWEB)

    Tao, L.; Schell, D.; Davis, R.; Tan, E.; Elander, R.; Bratis, A.


    For the DOE Bioenergy Technologies Office, the annual State of Technology (SOT) assessment is an essential activity for quantifying the benefits of biochemical platform research. This assessment has historically allowed the impact of research progress achieved through targeted Bioenergy Technologies Office funding to be quantified in terms of economic improvements within the context of a fully integrated cellulosic ethanol production process. As such, progress toward the ultimate 2012 goal of demonstrating cost-competitive cellulosic ethanol technology can be tracked. With an assumed feedstock cost for corn stover of $58.50/ton this target has historically been set at $1.41/gal ethanol for conversion costs only (exclusive of feedstock) and $2.15/gal total production cost (inclusive of feedstock) or minimum ethanol selling price (MESP). This year, fully integrated cellulosic ethanol production data generated by National Renewable Energy Laboratory (NREL) researchers in their Integrated Biorefinery Research Facility (IBRF) successfully demonstrated performance commensurate with both the FY 2012 SOT MESP target of $2.15/gal (2007$, $58.50/ton feedstock cost) and the conversion target of $1.41/gal through core research and process improvements in pretreatment, enzymatic hydrolysis, and fermentation.

  6. Optimization of reaction conditions for enzymatic viscosity reduction and hydrolysis of wheat arabinoxylan in an industrial ethanol fermentation residue

    DEFF Research Database (Denmark)

    Sørensen, H.R.; Pedersen, S.; Meyer, Anne Boye Strunge


    This study examined enzyme-catalyzed viscosity reduction and evaluated the effects of substrate dry matter concentration on enzymatic degradation of arabinoxylan in a fermentation residue, "vinasse", resulting from industrial ethanol manufacture on wheat. Enzymatic catalysis was accomplished with...... viscosity and that a compromise in the dry matter must be found if enzymatic efficiency must be balanced with monosaccharide yields.......This study examined enzyme-catalyzed viscosity reduction and evaluated the effects of substrate dry matter concentration on enzymatic degradation of arabinoxylan in a fermentation residue, "vinasse", resulting from industrial ethanol manufacture on wheat. Enzymatic catalysis was accomplished...... with increased enzyme dosage and treatment time at pH 5, 50 degrees C, 5 wt % vinasse dry matter. After 24 It of enzymatic treatment, 76-84%, 75-80%, and 43-47%, respectively, of the theoretically maximal arabinose, xylose, and glucose releases were achieved, indicating that the viscosity decrease was a result...

  7. Simultaneous saccharification and fermentation of ground corn stover for the production of fuel ethanol using Phanerochaete chrysosporium, Gloeophyllum trabeum, Saccharomyces cerevisiae, and Escherichia coli K011. (United States)

    Vincent, Micky; Pometto, Anthony L; van Leeuwen, J Hans


    Enzymatic saccharification of corn stover using Phanerochaete chrysosporium and Gloeophyllum trabeum and subsequent fermentation of the saccharification products to ethanol by Saccharomyces cerevisiae and Escherichia coli K011 were achieved. Prior to simultaneous saccharification and fermentation (SSF) for ethanol production, solid-state fermentation was performed for four days on ground corn stover using either P. chrysosporium or G. trabeum to induce in situ cellulase production. During SSF with S. cerevisiae or E. coli, ethanol production was the highest on day 4 for all samples. For corn stover treated with P. chrysosporium, the conversion to ethanol was 2.29 g/100 g corn stover with S. cerevisiae as the fermenting organism, whereas for the sample inoculated with E. coli K011, the ethanol production was 4.14 g/100 g corn stover. Corn stover treated with G. trabeum showed a conversion 1.90 and 4.79 g/100 g corn stover with S. cerevisiae and E. coli K011 as the fermenting organisms, respectively. Other fermentation co-products, such as acetic acid and lactic acid, were also monitored. Acetic acid production ranged between 0.45 and 0.78 g/100 g corn stover, while no lactic acid production was detected throughout the 5 days of SSF. The results of our experiment suggest that it is possible to perform SSF of corn stover using P. chrysosporium, G. trabeum, S. cerevisiae and E. coli K011 for the production of fuel ethanol.

  8. Efficient production of acetone-butanol-ethanol (ABE) from cassava by a fermentation-pervaporation coupled process. (United States)

    Li, Jing; Chen, Xiangrong; Qi, Benkun; Luo, Jianquan; Zhang, Yuming; Su, Yi; Wan, Yinhua


    Production of acetone-butanol-ethanol (ABE) from cassava was investigated with a fermentation-pervaporation (PV) coupled process. ABE products were in situ removed from fermentation broth to alleviate the toxicity of solvent to the Clostridium acetobutylicum DP217. Compared to the batch fermentation without PV, glucose consumption rate and solvent productivity increased by 15% and 21%, respectively, in batch fermentation-PV coupled process, while in continuous fermentation-PV coupled process running for 304 h, the substrate consumption rate, solvent productivity and yield increased by 58%, 81% and 15%, reaching 2.02 g/Lh, 0.76 g/Lh and 0.38 g/g, respectively. Silicalite-1 filled polydimethylsiloxane (PDMS)/polyacrylonitrile (PAN) membrane modules ensured media recycle without significant fouling, steadily generating a highly concentrated ABE solution containing 201.8 g/L ABE with 122.4 g/L butanol. After phase separation, a final product containing 574.3g/L ABE with 501.1g/L butanol was obtained. Therefore, the fermentation-PV coupled process has the potential to decrease the cost in ABE production.

  9. Multi-stage Continuous Culture Fermentation of Glucose-Xylose Mixtures to Fuel Ethanol using Genetically Engineered Saccharomyces cerevisiae 424A (United States)

    Multi-stage continuous (chemostat) culture fermentation (MCCF) with variable fermentor volumes was carried out to study utilizing glucose and xylose for ethanol production by means of mixed sugar fermentation (MSF). Variable fermentor volumes were used to enable enhanced sugar u...

  10. Ethanol and xylitol production by fermentation of acid hydrolysate from olive pruning with Candida tropicalis NBRC 0618. (United States)

    Mateo, Soledad; Puentes, Juan G; Moya, Alberto J; Sánchez, Sebastián


    Olive tree pruning biomass has been pretreated with pressurized steam, hydrolysed with hydrochloric acid, conditioned and afterwards fermented using the non-traditional yeast Candida tropicalis NBRC 0618. The main aim of this study was to analyse the influence of acid concentration on the hydrolysis process and its effect on the subsequent fermentation to produce ethanol and xylitol. From the results, it could be deduced that both total sugars and d-glucose recovery were enhanced by increasing the acid concentration tested; almost the whole hemicellulose fraction was hydrolysed when 3.77% was used. It has been observed a sequential production first of ethanol, from d-glucose, and then xylitol from d-xylose. The overall ethanol and xylitol yields ranged from 0.27 to 0.38kgkg(-1), and 0.12 to 0.23kgkg(-1) respectively, reaching the highest values in the fermentation of the hydrolysates obtained with hydrochloric acid 2.61% and 1.11%, respectively.

  11. Ethanol production from grass silage by simultaneous pretreatment, saccharification and fermentation: first steps in the process development

    Energy Technology Data Exchange (ETDEWEB)

    Sieker, Tim; Tippkoetter, Nils; Muffler, Kai; Ulber, Roland [Institute of Bioprocess Engineering, University of Kaiserslautern (Germany); Neuner, Andreas; Heinzle, Elmar [Biochemical Engineering, Saarland University, Saarbruecken (Germany); Dimitrova, Darina; Bart, Hans-Joerg [Chair of Separation Science and Technology, University of Kaiserslautern (Germany)


    Grass silage provides a great potential as renewable feedstock. Two fractions of the grass silage, a press juice and the fiber fraction, were evaluated for their possible use for bioethanol production. Direct production of ethanol from press juice is not possible due to high concentrations of organic acids. For the fiber fraction, alkaline peroxide or enzymatic pretreatment was used, which removes the phenolic acids in the cell wall. In this study, we demonstrate the possibility to integrate the enzymatic pretreatment with a simultaneous saccharification and fermentation to achieve ethanol production from grass silage in a one-process step. Achieved yields were about 53 g ethanol per kg silage with the alkaline peroxide pretreatment and 91 g/kg with the enzymatic pretreatment at concentrations of 8.5 and 14.6 g/L, respectively. Furthermore, it was shown that additional supplementation of the fermentation medium with vitamins, trace elements and nutrient salts is not necessary when the press juice is directly used in the fermentation step. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Bioconversion of corn stover derived pentose and hexose to ethanol using cascade simultaneous saccharification and fermentation (CSSF). (United States)

    Li, Xuan; Kim, Tae Hyun


    A cascade type of fermentation, designated the cascade simultaneous saccharification and fermentation (CSSF), was studied to convert corn stover derived pentose and hexose to ethanol with reduced enzyme input. In detail, each step of CSSF utilizes two sequential SSF phases operating on pentose and hexose, i.e., pentose conversion using xylanase, endo-glucanase, and recombinant Escherichia coli (KO11) with minimal glucose conversion in the first phase SSF, and hexose conversion in the second phase SSF using cellulase, β-glucosidase, and Saccharomyces cerevisiae (D(5)A). In this cascade scheme, multiple stages of 1st and 2nd phase SSF were performed in series; enzymes are recycled from the fermentation broth of the last stage for the use of the next stage. This bioconversion process yielded up to 60% of the theoretical maximum ethanol yield based on the total sugars in untreated corn stover, while enzyme loadings were reduced by 50% (v/v) and the final ethanol concentration reached 27 g/l.

  13. A comparison of the energy use of in situ product recovery techniques for the Acetone Butanol Ethanol fermentation. (United States)

    Outram, Victoria; Lalander, Carl-Axel; Lee, Jonathan G M; Davis, E Timothy; Harvey, Adam P


    The productivity of the Acetone Butanol Ethanol (ABE) fermentation can be significantly increased by application of various in situ product recovery (ISPR) techniques. There are numerous technically viable processes, but it is not clear which is the most economically viable in practice. There is little available information about the energy requirements and economics of ISPR for the ABE fermentation. This work compares various ISPR techniques based on UniSim process simulations of the ABE fermentation. The simulations provide information on the process energy and separation efficiency, which is fed into an economic assessment. Perstraction was the only technique to reduce the energy demand below that of a batch process, by approximately 5%. Perstraction also had the highest profit increase over a batch process, by 175%. However, perstraction is an immature technology, so would need significant development before being integrated to an industrial process.

  14. Ultrasonic pretreatment for enhanced saccharification and fermentation of ethanol production from corn (United States)

    Montalbo-Lomboy, Melissa T.

    The 21st Century human lifestyle has become heavily dependent on hydrocarbon inputs. Energy demand and the global warming effects due to the burning of fossil fuels have continued to increase. Rising awareness of the negative environmental and economic impacts of hydrocarbon dependence has led to a resurgence of interest in renewable energy sources such as ethanol. Fuel ethanol is known to be a cleaner and renewable source of energy relative to gasoline. Many studies have agreed that fuel ethanol has reduced greenhouse gas (GHG) emissions and has larger overall energy benefits compared to gasoline. Currently, the majority of the fuel ethanol in the United States is produced from corn using dry-grind milling process. The typical dry-grind ethanol plant incorporates jet cooking using steam to cook the corn slurry as pretreatment for saccharification; an energy intensive step. In aiming to reduce energy usage, this study evaluated the use of ultrasonics as an alternative to jet cooking. Ultrasonic batch experiments were conducted using a Branson 2000 Series bench-scale ultrasonic unit operating at a frequency of 20 kHz and a maximum output of 2.2 kW. Corn slurry was sonicated at varying amplitudes from 192 to 320 mumpeak-to-peak(p-p) for 0-40 seconds. Enzyme stability was investigated by adding enzyme (STARGEN(TM)001) before and after sonication. Scanning electron micrograph (SEM) images and particle size distribution analysis showed a nearly 20-fold size reduction by disintegration of corn particles due to ultrasonication. The results also showed a 30% improvement in sugar release of sonicated samples relative to the control group (untreated). The efficiency exceeded 100% in terms of relative energy gain from the additional sugar released due to ultrasonication compared to the ultrasonic energy applied. Interestingly, enzymatic activity was enhanced when sonicated at low and medium power. This result suggested that ultrasonic energy did not denature the enzymes

  15. Use of continuous lactose fermentation for ethanol production by Kluveromyces marxianus for verification and extension of a biochemically structured model

    DEFF Research Database (Denmark)

    Sansonetti, S.; Hobley, Timothy John; Curcio, S.


    A biochemically structured model has been developed to describe the continuous fermentation of lactose to ethanol by Kluveromyces marxianus and allowed metabolic coefficients to be determined. Anaerobic lactose-limited chemostat fermentations at different dilution rates (0.02 – 0.35 h-1) were per...... agreed very closely with those determined by regressions of the experimental data. The model developed provides a solid basis for the rational design of optimised fermentation of cheese whey....

  16. Bio-ethanol production by fermentation of ricotta cheese whey as an effective alternative non-vegetable source

    Energy Technology Data Exchange (ETDEWEB)

    Sansonetti, Sascha; Curcio, Stefano; Calabro, Vincenza; Iorio, Gabriele [Department of Engineering Modeling, University of Calabria, Ponte P. Bucci, Cubo 42/A, 87036 Rende, Cosenza (Italy)


    The aim of the present paper is to investigate the feasibility of bio-ethanol production by batch fermentation of ricotta cheese whey (''Scotta''), a dairy industry waste characterized by lactose concentration ranging from 4.5% to 5.0% (w/w) and, with respect to traditional (raw) whey, by much lower protein content. Scotta, therefore, could represent an effective non-vegetable source for renewable energy production. The microrganism used to carry out the fermentation processes was the yeast Kluyveromyces marxianus. Preliminary experiments, performed in aerobic conditions on different volumes of scotta, have shown the actual growth of the yeast. The subsequent fermentation experiments were carried out, in anaerobic conditions, on three different substrates: scotta, raw cheese whey and deproteinized whey. The experimental data have demonstrated the process feasibility: scotta is an excellent substrate for fermentation and exhibits better performance with respect to both raw cheese whey and deproteinized whey. Complete lactose consumption, indeed, was observed in the shortest time (13 h) and with the highest ethanol yield (97% of the theoretical value). (author)

  17. Simultaneous saccharification and fermentation of wheat bran flour into ethanol using coculture of amylotic Aspergillus niger and thermotolerant Kluyveromyces marxianus

    Institute of Scientific and Technical Information of China (English)



    Studies on simultaneous saccharification and fermentation (SSF) of wheat bran flour, a grain milling residue as the substrate using coculture method were carried out with strains of starch digesting Aspergillus niger and nonstarch digesting and sugar fermenting Kluyveromyces marxianus in batch fermentation. Experi-ments based on central composite design (CCD) were conducted to maximize the glucose yield and to study the effects of substrate concentration, pH, temperature, and enzyme concentration on percentage conversion of wheat bran flour starch to glucose by treatment with fungal α-amylase and the above parameters were optimized using response surface methodology (RSM). The optimum values of substrate concentration, pH, temperature, and enzyme concentration were found to be 200 g/L, 5.5, 65℃ and 7.5 IU, respectively, in the starch saccharification step. The effects of pH, temperature and substrate concentration on ethanol concentration, biomass and reducing sugar concentration were also investigated. The optimum temperature and pH were found to be 30℃ and 5.5, respectively. The wheat bran flour solution equivalent to 6% (w/V) initial starch concentration gave the highest ethanol concentration of 23.1 g/L after 48 h of fermentation at optimum conditions of pH and temperature. The growth kinetics was modeled using Monod model and Logistic model and product formation kinetics using Leudeking-Piret model. Simultaneous saccharificiation and fermenta-tion of liquefied wheat bran starch to bioethanol was studied using coculture of amylolytic fungus A. niger and nonamylolytic sugar fermenting K. marxianus.

  18. Comparison of solid-state and submerged-state fermentation for the bioprocessing of switchgrass to ethanol and acetate by Clostridium phytofermentans. (United States)

    Jain, Abhiney; Morlok, Charles K; Henson, J Michael


    The conversion of sustainable energy crops using microbiological fermentation to biofuels and bioproducts typically uses submerged-state processes. Alternatively, solid-state fermentation processes have several advantages when compared to the typical submerged-state processes. This study compares the use of solid-state versus submerged-state fermentation using the mesophilic anaerobic bacterium Clostridium phytofermentans in the conversion of switchgrass to the end products of ethanol, acetate, and hydrogen. A shift in the ratio of metabolic products towards more acetate and hydrogen production than ethanol production was observed when C. phytofermentans was grown under solid-state conditions as compared to submerged-state conditions. Results indicated that the end product concentrations (in millimolar) obtained using solid-state fermentation were higher than using submerged-state fermentation. In contrast, the total fermentation products (in weight of product per weight of carbohydrates consumed) and switchgrass conversion were higher for submerged-state fermentation. The conversion of xylan was greater than glucan conversion under both fermentation conditions. An initial pH of 7 and moisture content of 80 % resulted in maximum end products formation. Scanning electron microscopy study showed the presence of biofilm formed by C. phytofermentans growing on switchgrass under submerged-state fermentation whereas bacterial cells attached to surface and no apparent biofilm was observed when grown under solid-state fermentation. To our knowledge, this is the first study reporting consolidated bioprocessing of a lignocellulosic substrate by a mesophilic anaerobic bacterium under solid-state fermentation conditions.

  19. Production of Ethanol by Indigenous Wild and Mutant Strain of Thermotolerant Kluyveromyces Marxianus Under Optimized Fermentation Conditions

    Directory of Open Access Journals (Sweden)

    Shaheen Aziz


    Full Text Available The maximum ethanol production and β-fructofuranocidase formation under fermentation studies were carried out in microprocessor controlled 23-L stainless steel fermenter at the following conditions: Temp = 40 ˚C (wild &mutant organism , pH= 5.5, carbon source (molasses=15% sugar nitrogen source (ammonium sulphate 0.75%, 300 RPM stirring speed and oxygen flow rate was 0.1 vvm. Mutant. Strain of thermotolerant Kluyveromyces marxianus M15 produced maximum production of ethanol at 48hr.All Kinetic Parameters have been studied for the utilization of substrate and production of maximum ethanol for both wild and mutant strains. It has been observed that wild strain was growing up to 550C while the mutant strain was growing up to 650C. In this comparison study, wild and mutant strain showed that Mutant-derived M15 was stronger over its parental culture due to its more thermal stability and production of ethanol at 65 oC at which wild organism could not grow.

  20. Improved ethanol production by engineered Saccharomyces cerevisiae expressing a mutated cellobiose transporter during simultaneous saccharification and fermentation. (United States)

    Lee, Won-Heong; Jin, Yong-Su


    Although simultaneous saccharification and fermentation (SSF) of cellulosic biomass can offer efficient hydrolysis of cellulose through alleviating feed-back inhibition of cellulases by glucose, supplementation of β-glucosidase is necessary because most fermenting microorganisms cannot utilize cellobiose. Previously, we observed that SSF of cellulose by an engineered Saccharomyces cerevisiae expressing a cellobiose transporter (CDT-1) and an intracellular β-glucosidase (GH1-1) without β-glucosidase could not be performed as efficiently as the traditional SSF with extracellular β-glucosidase. However, we improved the ethanol production from SSF of cellulose by employing a further engineered S. cerevisiae expressing a mutant cellobiose transporter [CDT-1 (F213L) exhibiting higher VMAX than CDT-1] and GH1-1 in this study. Furthermore, limitation of cellobiose formation by reducing the amounts of cellulases mixture in SSF could lead the further engineered strain to produce ethanol considerably better than the parental strain with β-glucosidase. Probably, better production of ethanol by the further engineered strain seemed to be due to a higher affinity to cellobiose, which might be attributed to not only 2-times lower Monod constant (KS) for cellobiose than KS of the parental strain for glucose but also 5-times lower KS than Michaelis-Menten constant (KM) of the extracellular β-glucosidase for glucose. Our results suggest that modification of the cellobiose transporter in the engineered yeast to transport lower level of cellobiose enables a more efficient SSF for producing ethanol from cellulose.

  1. Recovery of ethanol from the fermented of grape pomace; Recuperacao de etanol a partir de bagaco fermentado de uva

    Energy Technology Data Exchange (ETDEWEB)

    Barnabe, Daniela [UNESP, Botucatu, SP (Brazil). Faculdade de Ciencias Agrarias. Programa de Pos-graduacao em Agronomia], e-mail:; Venturini Filho, Waldemar Gastoni [UNESP, Botucatu, SP (Brazil). Faculdade de Ciencias Agrarias. Dept. de Gestao e Tecnologia Agroindustrial], e-mail:


    Grape pomace, lees and tartrate are by-products obtained during the wine production. The pomace is usually used as a source of nutrients in the vineyard; however it contains alcohol in the interstice of skins due to alcoholic fermentation. By recovering alcohol from the pomace, a new product can be obtained before pomace is use in the field. The aim of this study was to recover the residual alcohol from grape pomace to produce an alcoholic distillate with energetic, economical and environmental advantages. Pomace was distilled in a simple copper still, and after re distilled for ethanol recovery. The recovered ethanol was then used in grape production. Ethanol yield was higher for Niagara grape distilled (7.0 L/100 kg) than for Bordo grape (6.2 L/100 kg); these results are due to the higher sugar content in Niagara Rosada grape. (author)

  2. Optimization of wastewater microalgae saccharification using dilute acid hydrolysis for acetone, butanol, and ethanol fermentation

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Yessica; Ellis, Joshua T.; Miller, Charles D.; Sims, Ronald C.


    Exploring and developing sustainable and efficient technologies for biofuel production are crucial for averting global consequences associated with fuel shortages and climate change. Optimization of sugar liberation from wastewater algae through acid hydrolysis was determined for subsequent fermentation to acetone, butanol, and ethanol (ABE) by Clostridium saccharoperbutylacetonicum N1-4. Acid concentration, retention time, and temperature were evaluated to determine optimal hydrolysis conditions by assessing the sugar and ABE yield as well as the associated costs. Sulfuric acid concentrations ranging from 0-1.5 M, retention times of 40-120 min, and temperatures from 23°C- 90°C were combined to form a full factorial experiment. Acid hydrolysis pretreatment of 10% dried wastewater microalgae using 1.0 M sulfuric acid for 120 min at 80-90°C was found to be the optimal parameters, with a sugar yield of 166.1 g for kg of dry algae, concentrations of 5.23 g/L of total ABE, and 3.74 g/L of butanol at a rate of USD $12.83 per kg of butanol.

  3. Two-stage Hydrolysis of Invasive Algal Feedstock for Ethanol Fermentation

    Institute of Scientific and Technical Information of China (English)

    Xin Wang; Xianhua Liu; Guangyi Wang


    The overall goal of this work was to develop a saccharification method for the production of third generation biofuel(i.e.bioethanol) using feedstock of the invasive marine macroalga Gracilaria salicornia.Under optimum conditions(120℃ and 2% sulfuric acid for 30 min), dilute acid hydrolysis of the homogenized invasive plants yielded a low concentration of glucose(4.1mM or 4.3g glucose/kg fresh algal biomass). However, two-stage hydrolysis of the homogenates (combination of dilute acid hydrolysis with enzymatic hydrolysis) produced 13.8g of glucose from one kilogram of fresh algal feedstock. Batch fermentation analysis produced 79.1g EtOH from one kilogram of dried invasive algal feedstock using the ethanologenic strain Escherichia coli K011. Furthermore, ethanol production kinetics indicated that the invasive algal feedstock contained different types of sugar, including C5-sugar. This study represents the first report on third generation biofuel production from invasive macroalgae, suggesting that there is great potential for the production of renewable energy using marine invasive biomass.

  4. 乙醇浓醪发酵技术研究进展%Research progress of high-concentration mash ethanol fermentation techniques

    Institute of Scientific and Technical Information of China (English)

    张强; 韩德明; 李明堂


    乙醇浓醪发酵具有高细胞密度、高产物浓度和高生产速率等特点,是乙醇工业的发展目标和方向。采用乙醇浓醪发酵技术,具有节约工艺用水、提高设备利用率、降低能耗等优势,是提高乙醇发酵工业效益的重要途径。研究乙醇浓醪发酵具有十分重要的现实意义。本文综述了乙醇浓醪发酵技术研究进展,介绍了乙醇浓醪发酵定义、优势以及影响乙醇浓醪发酵的因素。指出降低发酵醪液黏度、筛选高耐性酿酒酵母、改变发酵工艺模式、添加适宜酶制剂以及营养物质是实现乙醇浓醪发酵技术的主要途径,其中筛选高耐性的酿酒酵母是实现乙醇浓醪发酵技术的关键。%High-concentration mash fermentation has such characteristics as high cell density,high product concentration and high production rates. So it is the future aim of ethanol industry. High-concentration mash ethanol fermentation techniques have the advantages of saving process water,improving equipment utilization,and reducing energy consumption. So high-concentration mash ethanol fermentation techniques are an important way of improving ethanol production efficiency. Research on high-concentration mash ethanol fermentation techniques is very important in practical application. This paper reviews research progress of high-concentration mash ethanol fermentation techniques. The definition,advantages and influencing factors of high-concentration mash ethanol fermentation are introduced. Lowering the viscosity of fermentation mash,screening high-tolerance ethanol yeast,changing fermentation process model and adding appropriate enzymes and nutrients are important methods of achieving high-concentration mash ethanol fermentation. Among them,screening high-tolerance ethanol yeast is the key to high-concentration mash fermentation.

  5. Harvesting yeast (Saccharomyces cerevisiae) at different physiological phases significantly affects its functionality in bread dough fermentation. (United States)

    Rezaei, Mohammad N; Dornez, Emmie; Jacobs, Pieter; Parsi, Anali; Verstrepen, Kevin J; Courtin, Christophe M


    Fermentation of sugars into CO2, ethanol and secondary metabolites by baker's yeast (Saccharomyces cerevisiae) during bread making leads to leavening of dough and changes in dough rheology. The aim of this study was to increase our understanding of the impact of yeast on dough related aspects by investigating the effect of harvesting yeast at seven different points of the growth profile on its fermentation performance, metabolite production, and the effect on critical dough fermentation parameters, such as gas retention potential. The yeast cells harvested during the diauxic shift and post-diauxic growth phase showed a higher fermentation rate and, consequently, higher maximum dough height than yeast cells harvested in the exponential or stationary growth phase. The results further demonstrate that the onset of CO2 loss from fermenting dough is correlated with the fermentation rate of yeast, but not with the amount of CO2 that accumulated up to the onset point. Analysis of the yeast metabolites produced in dough yielded a possible explanation for this observation, as they are produced in different levels depending on physiological phase and in concentrations that can influence dough matrix properties. Together, our results demonstrate a strong effect of yeast physiology at the time of harvest on subsequent dough fermentation performance, and hint at an important role of yeast metabolites on the subsequent gas holding capacity.

  6. Effect of co-products of enzyme-assisted aqueous extraction of soybeans on ethanol production in dry-grind corn fermentation. (United States)

    Sekhon, Jasreen K; Jung, Stephanie; Wang, Tong; Rosentrater, Kurt A; Johnson, Lawrence A


    Enzyme-assisted aqueous extraction processing (EAEP) is an environmentally-friendly alternative to solvent and mechanical oil extraction methods, and can achieve ∼ 97% oil recovery from soybeans. The present study utilized soy skim (protein rich) and insoluble fiber (IF; carbohydrate rich), both co-products of EAEP, in dry-grind corn fermentation. The effects of adding soy skim and untreated IF (UIF), either separately or together, and adding pretreated IF (TIF), on ethanol production were investigated. Maximum ethanol production was achieved when UIF and skim were slurried together (corn-to-UIF ratio 1:0.16; skim-to-UIF ratio 6.5:1) and when fiber-hydrolyzing enzymes were added to corn fermentation. This modification to corn fermentation increased ethanol yield by 20%, ethanol production rate by 3%, and decreased fermentation time by 38 h compared to corn-only fermentation. An attempt was also made to utilize pentoses (from soy skim and IF) in integrated corn-soy fermentation slurry by an additional Escherichia coli KO11 fermentation step.

  7. Continuous acetone-butanol-ethanol (ABE) fermentation and gas production under slight pressure in a membrane bioreactor. (United States)

    Chen, Chunyan; Wang, Linyuan; Xiao, Guoqing; Liu, Yucheng; Xiao, Zeyi; Deng, Qing; Yao, Peina


    Two rounds of acetone-butanol-ethanol (ABE) fermentation under slight pressure were carried out in the continuous and closed-circulating fermentation (CCCF) system. Spores of the clostridium were observed and counted, with the maximum number of 2.1 × 10(8) and 2.3 × 10(8)ml(-1) separately. The fermentation profiles were comparable with that at atmospheric pressure, showing an average butanol productivity of 0.14 and 0.13 g L(-1)h(-1). Moreover, the average gas productivities of 0.28 and 0.27 L L(-1)h(-1) were obtained in two rounds of CCCF, and the cumulative gas production of 52.64 and 25.92 L L(-1) were achieved, with the hydrogen volume fraction of 41.43% and 38.08% respectively. The results suggested that slight pressures have no obvious effect on fermentation performance, and also indicated the significance and feasibility of gas recovery in the continuous ABE fermentation process.

  8. Simultaneous non-thermal saccharification of cassava pulp by multi-enzyme activity and ethanol fermentation by Candida tropicalis. (United States)

    Rattanachomsri, Ukrit; Tanapongpipat, Sutipa; Eurwilaichitr, Lily; Champreda, Verawat


    Cassava pulp, a solid by-product from starch processing, is a promising and underused biomass that can be converted to biofuels and other value-added bio-products. In this study, an alternative cassava pulp saccharification process, which utilizes the multi-activity enzyme from Aspergillus niger BCC17849 and obviates the need for a pre-gelatinization step, was developed. The crude multi-enzyme composed of non-starch polysaccharide hydrolyzing enzyme activities, including cellulase, pectinase and hemicellulase act cooperatively to release the trapped starch granules from the fibrous cell wall structure for subsequent saccharification by raw starch degrading activity. A high yield of fermentable sugars, equivalent to 716 mg glucose and 67 mg xylose/g of cassava pulp, was obtained after 48 h incubation at 40 degrees C and pH 5 using the multi-enzyme, which was greater than the yield obtained from the optimized combinations of the corresponding commercial enzymes. The multi-enzyme saccharification reaction can be performed simultaneously with the ethanol fermentation process using a thermotolerant yeast Candida tropicalis BCC7755. The combined process produced 14.3 g/l ethanol from 4% (w/v) cassava pulp after 30 h of fermentation. The productivity rate of 0.48 g/l/h is equivalent to 93.7% of the theoretical yield based on total starch and cellulose, or 85.4% based on total fermentable sugars. The non-thermal enzymatic saccharification process described is more energy efficient and yields more fermentable sugar than the conventional enzymatic process. Furthermore, the process is applicable for production of various bio-products of economic importance.

  9. Do new cellulolytic enzyme preparations affect the industrial strategies for high solids lignocellulosic ethanol production? (United States)

    Cannella, David; Jørgensen, Henning


    Production of ethanol from lignocellulosic materials has a promising market potential, but the process is still only at pilot/demonstration scale due to the technical and economical difficulties of the process. Operating the process at very high solids concentrations (above 20% dry matter-DM) has proven essential for economic feasibility at industrial scale. Historically, simultaneous saccharification and fermentation (SSF) was found to give better ethanol yields compared to separate hydrolysis and fermentation (SHF), but data in literature are typically based on operating the process at low dry matter conditions. In this work the impact of selected enzyme preparation and processing strategy (SHF, presaccharification and simultaneous saccharification and fermentation-PSSF, and SSF) on final ethanol yield and overall performance was investigated with pretreated wheat straw up to 30% DM. The experiments revealed that an SSF strategy was indeed better than SHF when applying an older generation enzyme cocktail (Celluclast-Novozym 188). In case of the newer product Cellic CTec 2, SHF resulted in 20% higher final ethanol yield compared to SSF. It was possible to close the mass balance around cellulose to around 94%, revealing that the most relevant products could be accounted for. One observation was the presence of oxidized sugar (gluconic acid) upon enzymatic hydrolysis with the latest enzyme preparation. Experiments showed gluconic acid formation by recently discovered enzymatic class of lytic polysaccharides monoxygenases (LPMO's) to be depending on the processing strategy. The lowest concentration was achieved in SSF, which could be correlated with less available oxygen due to simultaneous oxygen consumption by the yeast. Quantity of glycerol and cell mass was also depending on the selected processing strategy.

  10. Simultaneous saccharification and fermentation (SSF) of very high gravity (VHG) potato mash for the production of ethanol

    Energy Technology Data Exchange (ETDEWEB)

    Srichuwong, Sathaporn; Fujiwara, Maki; Wang, Xiaohui; Seyama, Tomoko; Shiroma, Riki; Arakane, Mitsuhiro; Tokuyasu, Ken [National Food Research Institute, National Agriculture and Food Research Organization (NARO), 2-1-12 Kannondai, Tsukuba, Ibaraki 305-8642 (Japan); Mukojima, Nobuhiro [National Agricultural Research Center for Hokkaido Region, NARO, 9-4 Shinsei-minami, Memuro-cho, Kasai-gun, Hokkaido 082-0071 (Japan)


    Simultaneous saccharification and fermentation (SSF) of very high gravity (VHG) potato mash, containing 304 g L{sup -1} of dissolved carbohydrates, was carried out for ethanol production. Potato tubers were ground into a mash, which was highly viscous. Mash viscosity was reduced by the pretreatment with mixed enzyme preparations of pectinase, cellulase and hemicellulase. The enzymatic pretreatment established the use of VHG mash with a suitable viscosity. Starch in the pretreated mash was liquefied to maltodextrins by the action of thermo-stable {alpha}-amylase at 85 C. SSF of liquefied mash was performed at 30 C with the simultaneous addition of glucoamylase, yeast (Saccharomyces cerevisiae) and ammonium sulfate as a nitrogen source for the yeast. The optimal glucoamylase loading, ammonium sulfate concentration and fermentation time were 1.65 AGU g{sup -1}, 30.2 mM and 61.5 h, respectively, obtained using the response surface methodology (RSM). Ammonium sulfate supplementation was necessary to avoid stuck fermentation under VHG condition. Using the optimized condition, ethanol yield of 16.61% (v/v) was achieved, which was equivalent to 89.7% of the theoretical yield. (author)

  11. Kinetic Modeling of Ethanol Batch Fermentation by Escherichia Coli FBWHR Using Hot-Water Sugar Maple Wood Extract Hydrolyzate as Substrate

    Directory of Open Access Journals (Sweden)

    Yang Wang


    Full Text Available A recombinant strain of Escherichia coli FBWHR was used for ethanol fermentation from hot-water sugar maple wood extract hydrolyzate in batch experiments. Kinetic studies of cell growth, sugar utilization and ethanol production were investigated at different initial total sugar concentrations of wood extract hydrolyzate. The highest ethanol concentration of 24.05 g/L was obtained using an initial total sugar concentration of 70.30 g/L. Unstructured models were developed to describe cell growth, sugar utilization and ethanol production and validated by comparing the predictions of model and experimental data. The results from this study could be expected to provide insights into the process performance, optimize the process and aid in the design of processes for large-scale production of ethanol fermentation from woody biomass.

  12. Studying the ability of Fusarium oxysporum and recombinant Saccharomyces cerevisiae to efficiently cooperate in decomposition and ethanolic fermentation of wheat straw

    DEFF Research Database (Denmark)

    Panagiotou, Gianni; Topakas, Evangelos; Moukouli, Maria


    by the addition of commercially available enzymes Celluclast® 1.5 L FG and Novozym® 188 in 3:1 ratio for the treatment of PWS, resulted in a 3-fold increase in the volumetric ethanol productivity without increasing the ethanol production significantly. By direct bioconversion of 110 kg m−3 dry matter of PWS......, ethanol concentration (4.9 kg m−3) and yield (40 g kg−1 of PWS) were similarly obtained by F. oxysporum and the mixed culture, while productivity rates as high as 34 g m−3 h−1 and 108 g m−3 h−1 were obtained by F. oxysporum and the mixed culture, respectively.......Fusarium oxysporum F3 alone or in mixed culture with Saccharomyces cerevisiae F12 were used to ferment carbohydrates of wet exploded pre-treated wheat straw (PWS) directly to ethanol. Both microorganisms were first grown aerobically to produce cell mass and thereafter fermented PWS to ethanol under...

  13. Capture of carbon dioxide from ethanol fermentation by liquid absorption for use in biological production of succinic acid. (United States)

    Nghiem, Nhuan P; Senske, Gerard E


    Previously, it was shown that the gas produced in an ethanol fermentor using either corn or barley as feedstock could be sparged directly into an adjacent fermentor as a feedstock for succinic acid fermentation using Escherichia coli AFP184. In the present investigation, it was demonstrated that the CO2 produced in a corn ethanol fermentor could be absorbed in a base solution and the resultant carbonate solution used both for pH control and supply of the CO2 requirement in succinic acid fermentation. Thus, the CO2 produced in a 5-L corn mash containing 30 wt% total solids was absorbed in a packed column containing 2 L of either 5 M NaOH, 5 M KOH, or 15 wt% NH4OH, and the resultant carbonate solutions were used for pH control in a succinic acid fermentor. The results obtained indicated no significant differences between succinic acid production in these experiments and when 2.5 M solutions of Na2CO3, K2CO3, and (NH4)2CO3 from commercial sources were used. In a commercial setting, the demonstrated capture of CO2 in liquid form will allow transportation of the carbonate solutions to locations not in the immediate vicinity of the ethanol plant, and excess carbonate salts can also be recovered as value-added products.

  14. Antimicrobial activity of ethanolic extract of propolis in “Alheira”, a fermented meat sausage

    Directory of Open Access Journals (Sweden)

    Rocío Casquete


    Full Text Available The objective of this study was to evaluate the efficacy of an ethanolic extract of propolis (EEP in the control of Listeria innocua PHLS 2030c (as a surrogate for Listeria monocytogenes during storage of Alheira at 4°C. Total phenolic content was evaluated to determine the minimal inhibitory concentration of EEP against the growth of L. innocua by the agar dilution method. Alheiras were manufactured by incorporating EEP (0.28 mg/mL and pathogenic bacteria and storage during 62 days at 4°C. Growth of L. innocua was determined during storage. The behaviour of L. innocua in the food matrix was significantly affected (p < 0.01 by the addition of EEP. The ethanolic extract of propolis reduced the Listeria population to below the detection limit of the technique after 8 days of storage. These results suggest that incorporation of EEP in a food susceptible to Listeria contamination may be an interesting alternative to existing chemical preservatives and can extend the shelf life of these products.

  15. Fermentation temperature affects the antioxidant activity of the enzyme-ripened sufu, an oriental traditional fermented product of soybean. (United States)

    Huang, Yung-Hsin; Lai, Ying-Jang; Chou, Cheng-Chun


    In this study, sufu, a Chinese traditional fermented product of soybean, was prepared by ripening salted tofu cubes in the mash of Aspergillus oryzae-fermented rice-soybean koji possessing various hydrolytic enzymes at 25°C, 37°C and 45°C. Antioxidant activity including 2,2-diphenyl-2-picylhydoxyl (DPPH) radical-scavenging activity, Fe(2+)-chelating ability and reducing power exerted by the methanol extract of sufu was determined and compared with that of the non-fermented tofu extract. It was found that antioxidant activity of the sufu extracts was, generally, higher than the non-fermented tofu extract. Ripening temperature and the duration of ripening period affected the antioxidant activity of the sufu extracts. Taking into account of extraction yields, the sufu product ripened at 45°C for 16 days showed the most profound enhancement in the DPPH radical-scavenging effect and Fe(2+)-iron-chelating ability, which is 3.4 and 11.5 folds, respectively, that noted with the non-fermented tofu.

  16. Ethanol yield and volatile compound content in fermentation of agave must by Kluyveromyces marxianus UMPe-1 comparing with Saccharomyces cerevisiae baker's yeast used in tequila production. (United States)

    López-Alvarez, Arnoldo; Díaz-Pérez, Alma Laura; Sosa-Aguirre, Carlos; Macías-Rodríguez, Lourdes; Campos-García, Jesús


    In tequila production, fermentation is an important step. Fermentation determines the ethanol productivity and organoleptic properties of the beverage. In this study, a yeast isolated from native residual agave must was identified as Kluyveromyces marxianus UMPe-1 by 26S rRNA sequencing. This yeast was compared with the baker's yeast Saccharomyces cerevisiae Pan1. Our findings demonstrate that the UMPe-1 yeast was able to support the sugar content of agave must and glucose up to 22% (w/v) and tolerated 10% (v/v) ethanol concentration in the medium with 50% cells survival. Pilot and industrial fermentation of agave must tests showed that the K. marxianus UMPe-1 yeast produced ethanol with yields of 94% and 96% with respect to fermentable sugar content (glucose and fructose, constituting 98%). The S. cerevisiae Pan1 baker's yeast, however, which is commonly used in some tequila factories, showed 76% and 70% yield. At the industrial level, UMPe-1 yeast shows a maximum velocity of fermentable sugar consumption of 2.27g·L(-1)·h(-1) and ethanol production of 1.38g·L(-1)·h(-1), providing 58.78g ethanol·L(-1) at 72h fermentation, which corresponds to 96% yield. In addition, the major and minor volatile compounds in the tequila beverage obtained from UMPe-1 yeast were increased. Importantly, 29 volatile compounds were identified, while the beverage obtained from Pan1-yeast contained fewer compounds and in lower concentrations. The results suggest that the K. marxianus UMPe-1 is a suitable yeast for agave must fermentation, showing high ethanol productivity and increased volatile compound content comparing with a S. cerevisiae baker's yeast used in tequila production.

  17. Fermentation Process Modeling with Levenberg-Marquardt Algorithm and Runge-Kutta Method on Ethanol Production by Saccharomyces cerevisiae

    Directory of Open Access Journals (Sweden)

    Dengfeng Liu


    Full Text Available The core of the Chinese rice wine making is a typical simultaneous saccharification and fermentation (SSF process. In order to control and optimize the SSF process of Chinese rice wine brewing, it is necessary to construct kinetic model and study the influence of temperature on the Chinese rice wine brewing process. An unstructured kinetic model containing 12 kinetics parameters was developed and used to describe the changing of kinetic parameters in Chinese rice wine fermentation at 22, 26, and 30°C. The effects of substrate and product inhibitions were included in the model, and four variable, including biomass, ethanol, sugar and substrate were considered. The R-square values for the model are all above 0.95 revealing that the model prediction values could match experimental data very well. Our model conceivably contributes significantly to the improvement of the industrial process for the production of Chinese rice wine.

  18. Adaptation to low pH and lignocellulosic inhibitors resulting in ethanolic fermentation and growth of Saccharomyces cerevisiae. (United States)

    Narayanan, Venkatachalam; Sànchez I Nogué, Violeta; van Niel, Ed W J; Gorwa-Grauslund, Marie F


    Lignocellulosic bioethanol from renewable feedstocks using Saccharomyces cerevisiae is a promising alternative to fossil fuels owing to environmental challenges. S. cerevisiae is frequently challenged by bacterial contamination and a combination of lignocellulosic inhibitors formed during the pre-treatment, in terms of growth, ethanol yield and productivity. We investigated the phenotypic robustness of a brewing yeast strain TMB3500 and its ability to adapt to low pH thereby preventing bacterial contamination along with lignocellulosic inhibitors by short-term adaptation and adaptive lab evolution (ALE). The short-term adaptation strategy was used to investigate the inherent ability of strain TMB3500 to activate a robust phenotype involving pre-culturing yeast cells in defined medium with lignocellulosic inhibitors at pH 5.0 until late exponential phase prior to inoculating them in defined media with the same inhibitor cocktail at pH 3.7. Adapted cells were able to grow aerobically, ferment anaerobically (glucose exhaustion by 19 ± 5 h to yield 0.45 ± 0.01 g ethanol g glucose(-1)) and portray significant detoxification of inhibitors at pH 3.7, when compared to non-adapted cells. ALE was performed to investigate whether a stable strain could be developed to grow and ferment at low pH with lignocellulosic inhibitors in a continuous suspension culture. Though a robust population was obtained after 3600 h with an ability to grow and ferment at pH 3.7 with inhibitors, inhibitor robustness was not stable as indicated by the characterisation of the evolved culture possibly due to phenotypic plasticity. With further research, this short-term adaptation and low pH strategy could be successfully applied in lignocellulosic ethanol plants to prevent bacterial contamination.

  19. KINETIKA FERMENTASI ASAM ASETAT (VINEGAR) OLEH BAKTERI Acetobacter aceti B 127 DARI ETANOL HASIL FERMENTASI LIMBAH CAIR PULP KAKAO [Kinetics of Acetic Acid (Vinegar) Fermentation By Acetobacter aceti B127 from Ethanol Produced by Fermentation of Liquid Waste of Cacao Pulp


    M. Supli Effendi


    Acetic acid concentration is one of vinegar’s quality parameter. Acetic acid concentration in vinegar is influenced by the activity of acetic acid bacteria. This research studied the kinetics of anaerobic fermentation of liquid waste of cacao pulp by Saccharomyces cerevisiae R60 to produce ethanol and the kinetics of acetic acid fermentation from ethanol by Acetobacter aceti B127. The kinetics of acetic acid fermentation from ethanol by Acetobacter aceti B127 can be used as a basic of biopro...

  20. Evaluation of apple pomace based reconstituted feed in rats after solid state fermentation and ethanol recovery

    Directory of Open Access Journals (Sweden)

    A. Devrajan


    Full Text Available To utilize apple pomace in an economical and effective way, a feed was developed by solid state fermentation (SSF using sequential interactive co-culture of Candida utilis and Kloeckera. Removal of ethanol and drying of the left - over residue. Feeding trial was conducted in white albino rats before and after reconstitution of apple pomace feed in the choice and no choice study. Feeding of apple pomace feed in the rats before reconstitution indicated that neither in fermented nor in unfermented form it was acceptable. In the no choice study both in 100% fermented and unfermented apple pomace group feed intake decreased continuously resulting in death of rats apparently due to decreased digestibility owing to high fibre content. Further, fermented or unfermented apple pomace based feed had lower digestibility and efficiency of conversion than the standard rat feed. Compared to the standard feed group, growth rates in all the feed groups were negative. The results of choice study of different feeds corroborated with the no-choice study mentioned earlier. Incorporation of fermented apple pomace into standard rat feed in the ratio of 1:1 gave better acceptability and digestibility. Reconstituted feed with 10% jaggery, 2% groundnut oil, 0.01% mixed flavour and 1% salt was the most acceptable. The post-mortem examination of the rats that died during the feeding trial revealed generalized oedema, probably due to some hepatotoxin in the feed. The blood glucose level in the apple pomace feed group except that was reconstituted with jaggery, showed a general hypoglycemia, though falling in the range. The increased ALT and AST levels in the serum also suggest damage to the liver. The mortality rate, post-mortem examination of the rats that died during the feeding trial and blood biochemical analysis of rat serum suggest a more elaborative study for extended period of time.Para utilizar bagaço de maçã de uma maneira econômica e eficaz, foi desenvolvido

  1. Production of ethanol from cassava pulp via fermentation with a surface-engineered yeast strain displaying glucoamylase

    Energy Technology Data Exchange (ETDEWEB)

    Kosugi, Akihiko; Murata, Yoshinori; Arai, Takamitsu; Mori, Yutaka [Post-harvest Science and Technology Division, Japan International Research Center for Agricultural Sciences (JIRCAS), 1-1 Ohwashi, Tsukuba, Ibaraki 305-8686 (Japan); Kondo, Akihiko [Department of Chemical Science and Engineering, Faculty of Engineering, Kobe University, Nada-ku, Kobe, 657-8501 (Japan); Ueda, Mitsuyoshi [Department of Applied Biochemistry, Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan); Vaithanomsat, Pilanee; Thanapase, Warunee [Nanotechnology and Biotechnology Division, Kasetsart Agricultural and Agro-Industrial Product Improvement Institute (KAPI), Kasetsart University, 50 Chatuchak, Ladyao, Bangkok 10900 (Thailand)


    Cassava (Manihot esculenta Crantz) pulp, produced in large amounts as a by-product of starch manufacturing, is a major biomass resource in Southeast Asian countries. It contains abundant starch (approximately 60%) and cellulose fiber (approximately 20%). To effectively utilize the cassava pulp, an attempt was made to convert its components to ethanol using a sake-brewing yeast displaying glucoamylase on the cell surface. Saccharomyces cerevisiae Kyokai no. 7 (strain K7) displaying Rhizopus oryzae glucoamylase, designated strain K7G, was constructed using the C-terminal-half region of {alpha}-agglutinin. A sample of cassava pulp was pretreated with a hydrothermal reaction (140 C for 1 h), followed by treatment with a Trichoderma reesei cellulase to hydrolyze the cellulose in the sample. The K7G strain fermented starch and glucose in pretreated samples without addition of amylolytic enzymes, and produced ethanol in 91% and 80% of theoretical yield from 5% and 10% cassava pulp, respectively. (author)

  2. 细微玉米粉的生料发酵%Ethanol Fermentation of Micronized Corn Flour

    Institute of Scientific and Technical Information of China (English)

    李学英; 谢俊彪; 毛继荣; 葛亮


    通过湿法球磨对玉米粉进行细微化处理,采用市售糖化酶和酵母菌进行生料发酵,调查细微化对玉米粉结晶结构及生料发酵的影响。结果发现,中位径为273.6μm的市售玉米粉经过湿磨球磨后,中位径达到8.3μm。X-射线衍射分析表明,玉米粉中淀粉颗粒在细微化处理后转变为非晶态。细微玉米粉生料发酵的速率和酒精度均显著高于市售玉米粉;初始pH和料液浓度对细微玉米粉生料发酵具有显著性影响,发酵初始pH为6,料液浓度为20%时,发酵效果最好,酒精度达11.2%,残糖含量最低。由此可见,细微化可使玉米粉颗粒非晶态化,促进玉米粉的生料发酵。%In order to study the effects of micronization on crystal structure and direct ethanol fermentation of corn flour, corn flour samples were prepared by wet-milling, and then the direct ethanol fermentation of corn flour were carried out by using commercially available glucoamylase and yeast. The commercial corn flour with a median diameter of 273.6μm was micronized to 8.3μm in median diameter by wet-milling. And X-ray diffra-cometry revealed that the crystals of starch granules in the corn flour could be destroyed by wet-milling. The fer-mentation rate and alcoholicity of micronized corn flour were significantly higher than that of the commercial corn flour. And when the initial pH and concentration of feed mixture were 6 and 20%respectively, the samples ferment most efficiently with alcoholicity of 11.2%.The results indicated that wet-milling led to the destruction of corn flour crystal structure, which resulted in a remarkable increase of alcoholicity in the ethanol fermentation of corn flour.

  3. Kinetics of sugars consumption and ethanol inhibition in carob pulp fermentation by Saccharomyces cerevisiae in batch and fed-batch cultures. (United States)

    Lima-Costa, Maria Emília; Tavares, Catarina; Raposo, Sara; Rodrigues, Brígida; Peinado, José M


    The waste materials from the carob processing industry are a potential resource for second-generation bioethanol production. These by-products are small carob kibbles with a high content of soluble sugars (45-50%). Batch and fed-batch Saccharomyces cerevisiae fermentations of high density sugar from carob pods were analyzed in terms of the kinetics of sugars consumption and ethanol inhibition. In all the batch runs, 90-95% of the total sugar was consumed and transformed into ethanol with a yield close to the theoretical maximum (0.47-0.50 g/g), and a final ethanol concentration of 100-110 g/l. In fed-batch runs, fresh carob extract was added when glucose had been consumed. This addition and the subsequent decrease of ethanol concentrations by dilution increased the final ethanol production up to 130 g/l. It seems that invertase activity and yeast tolerance to ethanol are the main factors to be controlled in carob fermentations. The efficiency of highly concentrated carob fermentation makes it a very promising process for use in a second-generation ethanol biorefinery.

  4. Regulation of pH attenuates toxicity of a byproduct produced by an ethanologenic strain of Sphingomonas sp. A1 during ethanol fermentation from alginate (United States)

    Fujii, Mari; Yoshida, Shiori; Murata, Kousaku; Kawai, Shigeyuki


    Marine macroalgae is a promising carbon source that contains alginate and mannitol as major carbohydrates. A bioengineered ethanologenic strain of the bacterium Sphingomonas sp. A1 can produce ethanol from alginate, but not mannitol, whereas the yeast Saccharomyces paradoxus NBRC 0259–3 can produce ethanol from mannitol, but not alginate. Thus, one practical approach for converting both alginate and mannitol into ethanol would involve two-step fermentation, in which the ethanologenic bacterium initially converts alginate into ethanol, and then the yeast produces ethanol from mannitol. In this study, we found that, during fermentation from alginate, the ethanologenic bacterium lost viability and secreted toxic byproducts into the medium. These toxic byproducts inhibited bacterial growth and killed bacterial cells and also inhibited growth of S. paradoxus NBRC 0259–3. We discovered that adjusting the pH of the culture supernatant or the culture medium containing the toxic byproducts to 6.0 attenuated the toxicity toward both bacteria and yeast, and also extended the period of viability of the bacterium. Although continuous adjustment of pH to 6.0 failed to improve the ethanol productivity of this ethanologenic bacterium, this pH adjustment worked very well in the two-step fermentation due to the attenuation of toxicity toward S. paradoxus NBRC 0259–3. These findings provide information critical for establishment of a practical system for ethanol production from brown macroalgae. PMID:24445222

  5. Effect of phytase application during high gravity (HG) maize mashes preparation on the availability of starch and yield of the ethanol fermentation process. (United States)

    Mikulski, D; Kłosowski, G; Rolbiecka, A


    Phytic acid present in raw materials used in distilling industry can form complexes with starch and divalent cations and thus limit their biological availability. The influence of the enzymatic hydrolysis of phytate complexes on starch availability during the alcoholic fermentation process using high gravity (HG) maize mashes was analyzed. Indicators of the alcoholic fermentation as well as the fermentation activity of Saccharomyces cerevisiae D-2 strain were statistically evaluated. Phytate hydrolysis improved the course of the alcoholic fermentation of HG maize mashes. The final ethanol concentration in the media supplemented with phytase applied either before or after the starch hydrolysis increased by 1.0 and 0.6 % v/v, respectively, as compared to the control experiments. This increase was correlated with an elevated fermentation yield that was higher by 5.5 and 2.0 L EtOH/100 kg of starch, respectively. Phytate hydrolysis resulted also in a statistically significant increase in the initial concentration of fermenting sugars by 14.9 mg/mL of mash, on average, which was a consequence of a better availability of starch for enzymatic hydrolysis. The application of phytase increased the attenuation of HG media fermentation thus improving the economical aspect of the ethanol fermentation process.

  6. Prenatal ethanol exposure differentially affects hippocampal neurogenesis in the adolescent and aged brain. (United States)

    Gil-Mohapel, J; Titterness, A K; Patten, A R; Taylor, S; Ratzlaff, A; Ratzlaff, T; Helfer, J; Christie, B R


    Exposure to ethanol in utero is associated with a myriad of sequelae for the offspring. Some of these effects are morphological in nature and noticeable from birth, while others involve more subtle changes to the brain that only become apparent later in life when the individuals are challenged cognitively. One brain structure that shows both functional and structural deficits following prenatal ethanol exposure is the hippocampus. The hippocampus is composed of two interlocking gyri, the cornu ammonis (CA) and the dentate gyrus (DG), and they are differentially affected by prenatal ethanol exposure. The CA shows a more consistent loss in neuronal numbers, with different ethanol exposure paradigms, than the DG, which in contrast shows more pronounced and consistent deficits in synaptic plasticity. In this study we show that significant deficits in adult hippocampal neurogenesis are apparent in aged animals following prenatal ethanol exposure. Deficits in hippocampal neurogenesis were not apparent in younger animals. Surprisingly, even when ethanol exposure occurred in conjunction with maternal stress, deficits in neurogenesis did not occur at this young age, suggesting that the capacity for neurogenesis is highly conserved early in life. These findings are unique in that they demonstrate for the first time that deficits in neurogenesis associated with prenatal ethanol consumption appear later in life.

  7. Periodic peristalsis increasing acetone-butanol-ethanol productivity during simultaneous saccharification and fermentation of steam-exploded corn straw. (United States)

    Li, Jingwen; Wang, Lan; Chen, Hongzhang


    The acetone-butanol-ethanol (ABE) fermentation of lignocellulose at high solids content has recently attracted extensive attention. However, the productivity of high solids ABE fermentation of lignocellulose is typically low in traditional processes due to the lack of efficient intensifying methods. In the present study, periodic peristalsis, a novel intensifying method, was applied to improve ABE production by the simultaneous saccharification and fermentation (SSF) of steam-exploded corn straw using Clostridium acetobutylicum ATCC824. The ABE concentration and the ABE productivity of SSF at a solids content of 17.5% (w/w) with periodic peristalsis were 17.1 g/L and 0.20 g/(L h), respectively, which were higher than those obtained under static conditions (15.2 g/L and 0.14 g/(L h)). The initial sugar conversion rate over the first 12 h with periodic peristalsis was 4.67 g/(L h) at 10 FPU/g cellulase dosage and 15% (w/w) solids content, an increase of 49.7% compared with the static conditions. With periodic peristalsis, the period of batch fermentation was shortened from 108 h to 84 h. The optimal operating regime was a low frequency (6 h(-1)) of periodic peristalsis in the acid-production phase (0-48 h) of SSF. Therefore, periodic peristalsis should be an effective intensifying method to increase the productivity of ABE fermentation at high solids content.

  8. High-efficiency carbohydrate fermentation to ethanol at temperatures above 40/sup 0/C by Kluyveromyces marxianus var. marxianus isolated from sugar mills

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, P.J.; NcNeil, K.; Watson, K.


    A number of yeast strains, isolated from sugar can mills and identified as strains of Kluyveromyces marxianus var. marxianus, were examined for their ability to ferment glucose and cane syrup to ethanol at high temperatures. Several strains were capable of rapid fermentation at temperatures up to 47/sup 0/C. At 43/sup 0/C, >6% (wt/vol) ethanol was produced after 12 to 14 h of fermentation, concurrent with retention of high cell viability (>80%). Although the type strain (CBS 712) of K. marxianus var. marxianus produced up to 6% (wt/vol) ethanol at 43/sup 0/C, cell viability was low, 30 to 50%, and the fermentation time was 24 to 30 h. On the basis of currently available strains, the authors suggest that it may be possible by genetic engineering to construct yeasts capable of fermenting carbohydrates at temperatures close to 50/sup 0/C to produce 10 to 15% (wt/vol) ethanol in 12 to 18 h with retention of cell viability.

  9. Simultaneous fermentation of glucose and xylose at elevated temperatures co-produces ethanol and xylitol through overexpression of a xylose-specific transporter in engineered Kluyveromyces marxianus. (United States)

    Zhang, Biao; Zhang, Jia; Wang, Dongmei; Han, Ruixiang; Ding, Rui; Gao, Xiaolian; Sun, Lianhong; Hong, Jiong


    Engineered Kluyveromyces marxianus strains were constructed through over-expression of various transporters for simultaneous co-fermentation of glucose and xylose. The glucose was converted into ethanol, whereas xylose was converted into xylitol which has higher value than ethanol. Over-expressing xylose-specific transporter ScGAL2-N376F mutant enabled yeast to co-ferment glucose and xylose and the co-fermentation ability was obviously improved through increasing ScGAL2-N376F expression. The production of glycerol was blocked and acetate production was reduced by disrupting gene KmGPD1. The obtained K. marxianus YZJ119 utilized 120g/L glucose and 60g/L xylose simultaneously and produced 50.10g/L ethanol and 55.88g/L xylitol at 42°C. The yield of xylitol from consumed xylose was over 98% (0.99g/g). Through simultaneous saccharification and co-fermentation at 42°C, YZJ119 produced a maximal concentration of 44.58g/L ethanol and 32.03g/L xylitol or 29.82g/L ethanol and 31.72g/L xylitol, respectively, from detoxified or non-detoxified diluted acid pretreated corncob.

  10. Riview on the Development of the Pentose Ethanol Fermentation%戊糖乙醇发酵的研究进展

    Institute of Scientific and Technical Information of China (English)

    杨雕; 苏江滨


    戊糖乙醇发酵技术是决定植物纤维资源生产酒精经济可行的关键技术之一,本文综合叙述戊糖乙醇发酵的研究进展。能利用戊糖发酵乙醇的微生物有多种,目前研究较多的主要是酵母菌;用酵母菌发酵戊糖的过程有木酮糖途径和木糖醇途径;对戊糖酵母茵的选育主要从4个方面入手,采用的发酵方式主要有5种。%Ethanol fermentation from pentose is the key technology which uses the plant fibre resources economically and workably manufacture ethanol, and this paper presents a review of the research and development for ethanol fermentation from pentose. There are many microorganisms used for ethanol fermentation from pentose which mainly adopt yeasts to produce ethanol at present. In the yeast, there are two main approach of fermentation: xylulose route and xylose route. Nowadays, the yeast stem selection mostly contains four aspects and the fermentation modes contain five types.

  11. Two-stage pervaporation process for effective in situ removal acetone-butanol-ethanol from fermentation broth. (United States)

    Cai, Di; Hu, Song; Miao, Qi; Chen, Changjing; Chen, Huidong; Zhang, Changwei; Li, Ping; Qin, Peiyong; Tan, Tianwei


    Two-stage pervaporation for ABE recovery from fermentation broth was studied to reduce the energy cost. The permeate after the first stage in situ pervaporation system was further used as the feedstock in the second stage of pervaporation unit using the same PDMS/PVDF membrane. A total 782.5g/L of ABE (304.56g/L of acetone, 451.98g/L of butanol and 25.97g/L of ethanol) was achieved in the second stage permeate, while the overall acetone, butanol and ethanol separation factors were: 70.7-89.73, 70.48-84.74 and 9.05-13.58, respectively. Furthermore, the theoretical evaporation energy requirement for ABE separation in the consolidate fermentation, which containing two-stage pervaporation and the following distillation process, was estimated less than ∼13.2MJ/kg-butanol. The required evaporation energy was only 36.7% of the energy content of butanol. The novel two-stage pervaporation process was effective in increasing ABE production and reducing energy consumption of the solvents separation system.

  12. Enzymatic digestibility and ethanol fermentability of AFEX-treated starch-rich lignocellulosics such as corn silage and whole corn plant


    Thelen Kurt D; Sousa Leonardo; Bals Bryan; Krishnan Chandraraj; Chundawat Shishir PS; Shao Qianjun; Dale Bruce E; Balan Venkatesh


    Abstract Background Corn grain is an important renewable source for bioethanol production in the USA. Corn ethanol is currently produced by steam liquefaction of starch-rich grains followed by enzymatic saccharification and fermentation. Corn stover (the non-grain parts of the plant) is a potential feedstock to produce cellulosic ethanol in second-generation biorefineries. At present, corn grain is harvested by removing the grain from the living plant while leaving the stover behind on the fi...

  13. Application of bacteriophage endolysins to reduce Lactobacillus contamination during fuel ethanol fermentation (United States)

    Bacterial contamination is a recurring problem in the fuel ethanol industry. The offending microbes are generally species of lactic acid bacteria that drain the sugar available for conversion to ethanol and scavenge essential micronutrients required for optimal yeast growth. Antibiotics are frequent...


    Ethanol is commonly used as a fuel oxygenate in California and in the mid continent area around the Great Lakes. The presence of ethanol in a gasoline spill has raised concerns about the effects of the additive on the natural biodegradation of fuel hydrocarbons, including benzen...

  15. Optimization and validation of a GC-FID method for the determination of acetone-butanol-ethanol fermentation products. (United States)

    Lin, Xiaoqing; Fan, Jiansheng; Wen, Qingshi; Li, Renjie; Jin, Xiaohong; Wu, Jinglan; Qian, Wenbin; Liu, Dong; Xie, Jingjing; Bai, Jianxin; Ying, Hanjie


    An improved, simple gas chromatography-flame ionization detection (GC-FID) method was developed for measuring the products of acetone-butanol-ethanol (ABE) fermentation and the combined fermentation/separation processes. The analysis time per sample was reduced to less than 10 min compared to those of a conventional GC-FID (more than 20 min). The behavior of the compounds in temperature-programmed gas chromatographic runs was predicted using thermodynamic parameters derived from isothermal runs. The optimum temperature programming condition was achieved when the resolution for each peak met the analytical requirement and the analysis time was shortest. With the exception of acetic acid, the detection limits of the presented method for various products were below 10 mg/L. The repeatability and intermediate precision of the method were less than 10% (relative standard deviation). Validation and quantification results demonstrated that this method is a sensitive, reliable and fast alternative for conventional investigation of the adsorption-coupled ABE fermentation process.

  16. Effective multiple stages continuous acetone-butanol-ethanol fermentation by immobilized bioreactors: Making full use of fresh corn stalk. (United States)

    Chang, Zhen; Cai, Di; Wang, Yong; Chen, Changjing; Fu, Chaohui; Wang, Guoqing; Qin, Peiyong; Wang, Zheng; Tan, Tianwei


    In order to make full use of the fresh corn stalk, the sugar containing juice was used as the sole substrate for acetone-butanol-ethanol production without any nutrients supplement, and the bagasse after squeezing the juice was used as the immobilized carrier. A total 21.34g/L of ABE was produced in batch cells immobilization system with ABE yield of 0.35g/g. A continuous fermentation containing three stages with immobilized cells was conducted and the effect of dilution rate on fermentation was investigated. As a result, the productivity and ABE solvents concentration reached 0.80g/Lh and 19.93g/L, respectively, when the dilution rate in each stage was 0.12/h (corresponding to a dilution rate of 0.04/h in the whole system). And the long-term operation indicated the continuous multiple stages ABE fermentation process had good stability and showed the great potential in future industrial applications.

  17. Ammonia fiber expansion (AFEX) pretreatment, enzymatic hydrolysis, and fermentation on empty palm fruit bunch fiber (EPFBF) for cellulosic ethanol production. (United States)

    Lau, Ming J; Lau, Ming W; Gunawan, Christa; Dale, Bruce E


    Empty palm fruit bunch fiber (EPFBF), a readily available cellulosic biomass from palm processing facilities, is investigated as a potential carbohydrate source for cellulosic ethanol production. This feedstock was pretreated using ammonia fiber expansion (AFEX) and enzymatically hydrolyzed. The best tested AFEX conditions were at 135 °C, 45 min retention time, water to dry biomass loading of 1:1 (weight ratio), and ammonia to dry biomass loading of 1:1 (weight ratio). The particle size of the pretreated biomass was reduced post-AFEX. The optimized enzyme formulation consists of Accellerase (84 μL/g biomass), Multifect Xylanase (31 μL/g biomass), and Multifect Pectinase (24 μL/g biomass). This mixture achieved close to 90% of the total maximum yield within 72 h of enzymatic hydrolysis. Fermentation on the water extract of this biomass affirms that nutrients solely from the pretreated EPFBF can support yeast growth for complete glucose fermentation. These results suggest that AFEX-treated EPFBF can be used for cellulosic biofuels production because biomass recalcitrance has been overcome without reducing the fermentability of the pretreated materials.

  18. 玉米秸秆、玉米芯发酵生产乙醇的研究%Study on Ethanol Fermentation of Corn Straw, Corn Cob

    Institute of Scientific and Technical Information of China (English)

    田亚红; 常丽新; 王丽萍; 徐宵娲


    The effects of the individual and mixed fermentation of two kinds of raw materials corn stalk ,corn cob on ethanol production were studied by single factor and orthogonal experiments.The results showed that corn straw and corn cob respectively were basically the same as optimum conditions for production of ethanol by fermentation:fermentation time 72 h, inoculum 5%,pH 4.8;The mixed fermentation for ethanol productionwere as follows:fermentation time 72 h,inoculum for 5%,pH 5.3,corn straw:corn cob(ratio to weight) of 2∶3,ethanol concentrations 7.96%,Compared with separated fermentation, ethanol concentration increased by 20.6%.%通过单因素和正交试验,研究了玉米秸秆、玉米芯两种原料分别发酵和混合发酵对乙醇生产的影响。结果表明,玉米秸秆和玉米芯分别发酵生产乙醇的最佳条件基本一致为:发酵时间72 h,接种量5%,pH为4.8;玉米秸秆和玉米芯混合发酵生产乙醇的最佳条件为:发酵时间72 h,接种量为5%,pH 5.3,玉米秸秆:玉米芯(质量比)为2∶3,乙醇浓度达7.96%,与分别发酵相比,乙醇浓度提高了20.6%。

  19. Effect of dilute alkaline pretreatment on the conversion of different parts of corn stalk to fermentable sugars and its application in acetone-butanol-ethanol fermentation. (United States)

    Cai, Di; Li, Ping; Luo, Zhangfeng; Qin, Peiyong; Chen, Changjing; Wang, Yong; Wang, Zheng; Tan, Tianwei


    To investigate the effect of dilute alkaline pretreatment on different parts of biomass, corn stalk was separated into flower, leaf, cob, husk and stem, which were treated by NaOH in range of temperature and chemical loading. The NaOH-pretreated solid was then enzymatic hydrolysis and used as the substrate for batch acetone-butanol-ethanol (ABE) fermentation. The results demonstrated the five parts of corn stalk could be used as potential feedstock separately, with vivid performances in solvents production. Under the optimized conditions towards high product titer, 7.5g/L, 7.6g/L, 9.4g/L, 7g/L and 7.6g/L of butanol was obtained in the fermentation broth of flower, leaf, cob, husk and stem hydrolysate, respectively. Under the optimized conditions towards high product yield, 143.7g/kg, 126.3g/kg, 169.1g/kg, 107.7g/kg and 116.4g/kg of ABE solvent were generated, respectively.

  20. Carbon monoxide fermentation to ethanol by Clostridium autoethanogenum in a bioreactor with no accumulation of acetic acid. (United States)

    Abubackar, Haris Nalakath; Veiga, María C; Kennes, Christian


    Fermentation of CO or syngas offers an attractive route to produce bioethanol. However, during the bioconversion, one of the challenges to overcome is to reduce the production of acetic acid in order to minimize recovery costs. Different experiments were done with Clostridium autoethanogenum. With the addition of 0.75 μM tungsten, ethanol production from carbon monoxide increased by about 128% compared to the control, without such addition, in batch mode. In bioreactors with continuous carbon monoxide supply, the maximum biomass concentration reached at pH 6.0 was 109% higher than the maximum achieved at pH 4.75 but, interestingly, at pH 4.75, no acetic acid was produced and the ethanol titer reached a maximum of 867 mg/L with minor amounts of 2,3-butanediol (46 mg/L). At the higher pH studied (pH 6.0) in the continuous gas-fed bioreactor, almost equal amounts of ethanol and acetic acid were formed, reaching 907.72 mg/L and 910.69 mg/L respectively.

  1. Ethanol production from sunflower meal biomass by simultaneous saccharification and fermentation (SSF) with Kluyveromyces marxianus ATCC 36907. (United States)

    Camargo, Danielle; Gomes, Simone D; Sene, Luciane


    The lignocellulosic materials are considered promising renewable resources for ethanol production, but improvements in the processes should be studied to reduce operating costs. Thus, the appropriate enzyme loading for cellulose saccharification is critical for process economics. This study aimed at evaluating the concentration of cellulase and β-glucosidase in the production of bioethanol by simultaneous saccharification and fermentation (SSF) of sunflower meal biomass. The sunflower biomass was pretreated with 6% H2SO4 (w/v), at 121 °C, for 20 min, for hemicellulose removal and delignificated with 1% NaOH. SSF was performed with Kluyveromyces marxianus ATCC 36907, at 38 °C, 150 rpm, for 72 h, with different enzyme concentrations (Cellulase Complex NS22086-10, 15 and 20 FPU/gsubstrate and β-Glucosidase NS22118, with a cellulase to β-glucosidase ratio of 1.5:1; 2:1 and 3:1). The best condition for ethanol production was cellulase 20 FPU/gsubstrate and β-glucosidase 13.3 CBU/gsubstrate, resulting in 27.88 g/L ethanol, yield of 0.47 g/g and productivity of 0.38 g/L h. Under this condition the highest enzymatic conversion of cellulose to glucose was attained (87.06%).

  2. Effect of the presence of initial ethanol on ethanol production in sugar cane juice fermented by Zymomonas mobilis Efeito da presença de etanol inicial na produção de etanol em caldo de cana-de-açúcar fermentado por Zymomonas mobilis

    Directory of Open Access Journals (Sweden)

    Marcia Sadae Tano


    Full Text Available Ethanol production in sugar cane juice in high initial sugar concentration, fermented by Z. mobilis in the presence and absence of ethanol, was evaluated. Ethanol production was low in both media. The presence of initial ethanol in the sugar cane juice reduced ethanol production by 48.8%, biomass production by 25.0% and the total sugar consumption by 28.3%. The presence of initial ethanol in the medium did not affect significantly levan production and biomass yield coefficient (g biomass/g sugar consumed.Foi avaliada a produção de etanol em caldo de cana-de-açúcar com alta concentração de açúcar inicial, fermentado por Z. mobilis, na presença e na ausência de etanol inicial. A produção de etanol nos dois meios foi baixa. A presença de etanol inicial no caldo de cana-de-açúcar causou uma redução de 48,8% na produção de etanol, de 25% na produção de biomassa e de 28,3% no consumo de açúcar total. A presença de etanol inicial ao meio não teve efeito significante para a produção de levana e no coeficiente de produtividade em biomassa (g biomassa/g açúcar consumido.

  3. Ethanol and Acetate Acting as Carbon/Energy Sources Negatively Affect Yeast Chronological Aging

    Directory of Open Access Journals (Sweden)

    Ivan Orlandi


    Full Text Available In Saccharomyces cerevisiae, the chronological lifespan (CLS is defined as the length of time that a population of nondividing cells can survive in stationary phase. In this phase, cells remain metabolically active, albeit at reduced levels, and responsive to environmental signals, thus simulating the postmitotic quiescent state of mammalian cells. Many studies on the main nutrient signaling pathways have uncovered the strong influence of growth conditions, including the composition of culture media, on CLS. In this context, two byproducts of yeast glucose fermentation, ethanol and acetic acid, have been proposed as extrinsic proaging factors. Here, we report that ethanol and acetic acid, at physiological levels released in the exhausted medium, both contribute to chronological aging. Moreover, this combined proaging effect is not due to a toxic environment created by their presence but is mainly mediated by the metabolic pathways required for their utilization as carbon/energy sources. In addition, measurements of key enzymatic activities of the glyoxylate cycle and gluconeogenesis, together with respiration assays performed in extreme calorie restriction, point to a long-term quiescent program favoured by glyoxylate/gluconeogenesis flux contrary to a proaging one based on the oxidative metabolism of ethanol/acetate via TCA and mitochondrial respiration.

  4. Effects of ethanol, molasses and Lactobacillus plantarum on the fermentation quality, in vitro digestibility and aerobic stability of total mixed ration silages in the Tibetan plateau of China. (United States)

    Yuan, Xianjun; Wen, Aiyou; Wang, Jian; Guo, Gang; Desta, Seare T; Shao, Tao


    In Tibet, it is common practice to make and relocate total mixed ration (TMR) silages before feeding due to the uneven distribution of forages temporally and spatially. This study was conducted to investigate the effects of Lactobacillus plantarum (L), molasses (M) or ethanol (E) on the fermentation quality and aerobic stability of local adaptive TMR silage. After 45 days of ensiling, pH and ammonia nitrogen in inoculated TMR silages were significantly lower than control. During the first 6 days of the aerobic exposure test, a small fluctuation in lactic acid concentration for all TMR silages was observed, and then silages with ethanol continued this trend, while lactic acid in silage without ethanol sharply decreased until the end of the aerobic exposure period. Meanwhile, pH gradually increased along the aerobic exposure; silages treated with ethanol showed lower pH after 9 days of aerobic exposure. The population of yeast gradually increased during 6 days of aerobic exposure, after that an accelerated rise was observed in TMR silages without ethanol. The combinational beneficial effect of L. plantarum and ethanol was found in combined addition of ethanol and Lactobacillus plantarum silages (EL), indicated by intermediate fermentation quality and higher aerobic stability.

  5. Efficient production of ethanol from empty palm fruit bunch fibers by fed-batch simultaneous saccharification and fermentation using Saccharomyces cerevisiae. (United States)

    Park, Jang Min; Oh, Baek-Rock; Seo, Jeong-Woo; Hong, Won-Kyung; Yu, Anna; Sohn, Jung-Hoon; Kim, Chul Ho


    The concentration of ethanol produced from lignocellulosic biomass should be at least 40 g l(-1) [about 5 % (v/v)] to minimize the cost of distillation process. In this study, the conditions for the simultaneous saccharification and fermentation (SSF) at fed-batch mode for the production of ethanol from alkali-pretreated empty palm fruit bunch fibers (EFB) were investigated. Optimal conditions for the production of ethanol were identified as temperature, 30 °C; enzyme loading, 15 filter paper unit g(-1) biomass; and yeast (Saccharomyces cerevisiae) loading, 5 g l(-1) of dry cell weight. Under these conditions, an economical ethanol concentration was achieved within 17 h, which further increased up to 62.5 g l(-1) after 95 h with 70.6 % of the theoretical yield. To our knowledge, this is the first report to evaluate the economic ethanol production from alkali-pretreated EFB in fed-batch SSF using S. cerevisiae.

  6. Dark fermentative hydrogen and ethanol production from biodiesel waste glycerol using a co-culture of Escherichia coli and Enterobacter sp.

    NARCIS (Netherlands)

    Maru, B.T.; López, F.; Kengen, S.W.M.; Constantí, M.; Medina, F.


    In previous comparative studies, Enterobacter spH1 was selected as the best hydrogen and ethanol producer (Knothe, 2010). Here, glycerol fermentation was compared between three other strains: Escherichia coli CECT432, Escherichia coli CECT434 and Enterobacter cloacae MCM2/1. E. coli CECT432 was f

  7. A step towards on-chip biochemical energy cascade of microorganisms: carbon dioxide generation induced by ethanol fermentation in 3D printed modular lab-on-a-chip (United States)

    Podwin, A.; Kubicki, W.; Adamski, K.; Walczak, R.; Dziuban, J. A.


    The concept of biochemical energy cascade of microorganisms towards oxygen generation in 3D printed lab-on-a-chip has been presented. In this work, carbon dioxide - a product of ethanol fermentation of yeasts has been utilized to enable light-initialized photosynthesis of euglenas and as a result of their metabolic transitions produce pure oxygen.

  8. Logistic模型模拟乙醇发酵产物动力学%Product kinetics of Logistic model to simulate ethanol fermentation

    Institute of Scientific and Technical Information of China (English)

    岳国君; 刘文信; 刘劲松; 杨晓光; 丁乾坤; 董红星; 宋启龙; 关晓男


    乙醇发酵产物动力学的研究有助于更好的认识发酵过程,为其工业放大及生产操作条件的优化提供理论基础。基于 Logistic 方程的菌体生长动力学模型可较好的描述细胞生长期及细胞自身抑制作用,但由于该模型方程中的比例参数与积分常数没有明显的生物学意义,使其应用受到了限制。该文从生物学与化学工程学结合角度对 Logistic 模型方程重新参数化,将发酵产物乙醇生成动力学与酵母生长动力学方程类比,给出了乙醇浓度的显式函数模型,模型中不再出现酵母菌浓度变量,大大简化了模型,并且赋予参数其物理意义;在研究了以葡萄糖和玉米淀粉为原料乙醇质量浓度、总糖质量浓度在不同底物质量浓度和料液比条件下随发酵时间的变化规律的基础上运用该模型拟合了以葡萄糖和玉米淀粉为原料进行乙醇发酵的试验数据,结果表明:模型值与试验数据具有较好一致性,拟合度均大于0.97,可见该重新参数化的 Logistic 模型可以描述发酵生产乙醇过程中产物乙醇的动力学行为,具有预测工业上实际发酵过程中乙醇浓度的潜力。%Ethanol plays an important role in the national economy, and is widely used in the raw materials of food, medicine, and the chemical industry. In recent years, with the challenge facing the world’s energy security, more and more attention has been devoted to the conversion of biomass into fuel ethanol. Ethanol is considered to be a renewable and clean fuel, which can be an alternative to fossil fuels. So far, compared with other ethanol production methods, the fermentation method to produce ethanol has so many advantages, such as green environmental protection and low cost, that attracts lots of researchers’ attention. There are many influence factors in the fermentation process, which make the fermentation process so complicated that it is hard

  9. Two-step size reduction and post-washing of steam exploded corn stover improving simultaneous saccharification and fermentation for ethanol production. (United States)

    Liu, Zhi-Hua; Chen, Hong-Zhang


    The simultaneous saccharification and fermentation (SSF) of corn stover biomass for ethanol production was performed by integrating steam explosion (SE) pretreatment, hydrolysis and fermentation. Higher SE pretreatment severity and two-step size reduction increased the specific surface area, swollen volume and water holding capacity of steam exploded corn stover (SECS) and hence facilitated the efficiency of hydrolysis and fermentation. The ethanol production and yield in SSF increased with the decrease of particle size and post-washing of SECS prior to fermentation to remove the inhibitors. Under the SE conditions of 1.5MPa and 9min using 2.0cm particle size, glucan recovery and conversion to glucose by enzymes were 86.2% and 87.2%, respectively. The ethanol concentration and yield were 45.0g/L and 85.6%, respectively. With this two-step size reduction and post-washing strategy, the water utilization efficiency, sugar recovery and conversion, and ethanol concentration and yield by the SSF process were improved.

  10. Ethanol fermentation on glucose/xylose mixture by co-cultivation of restricted glucose catabolite repressed mutants of Pichia stipitis with respiratory deficient mutants of Saccharomyces cerevisiae. (United States)

    Kordowska-Wiater, Monika; Targoński, Zdzisław


    Restricted glucose catabolite repressed mutants of P. stipiti CCY 39501 were selected using UV irradiation. Four mutants were obtained which assimilated glucose slower than the native strain of P. stipitis and the degree of glucose repression was about 2-fold lower for P5-90-133 and P5-200-16 mutants and about 10-fold lower for P5-80-7 and P5-80-35 mutants. P5-80-7 and P5-80-35 produced very small amounts of ethanol from glucose and xylose, whereas P5-90-133 and P5-200-16 fermented sugars at the wild-type level. These two mutants were selected for co-fermentation process with native strain of S. cerevisiae V30 or Ja(a), as well as with their respiratory deficient mutants. During co-culture process of P. stipitis mutants with native strains of S. cerevisiae the ethanol yields obtained ranged from 0.38 to 0.45 g/g, and this alcohol was produced mainly from glucose. But, when also xylose, besides glucose was fermented to ethanol during co-fermentation of both mutant strains, lower yields of ethanol (0.28-0.40 g/g) were obtained.

  11. Control of packed column fouling in the continuous fermentation and stripping of ethanol. (United States)

    Taylor, F; Kurantz, M J; Goldberg, N; Craig, J C


    By recycling the contents of a 14 L fermentor through a stripping column to continuously remove ethanol and reduce product inhibition, continuous complete conversion of nutrient feed containing 600 g/L glucose was achieved in a small pilot plant. Ethanol was recovered from the carbon dioxide stripping gas in a refrigerated condenser, and the gas was reheated with steam and recycled by a blower. Productivity of ethanol in the fermentor as high as 15.8 g/L/h and condensate production of up to 10 L/day of almost 50% by volume ethanol were maintained for up to 60 days of continuous operation. Weekly washing of the column packing in situ was required to prevent loss of performance caused by attached growth of yeast cells, which restricts the gas flow rate through the stripping column. (c) 1996 John Wiley & Sons, Inc.

  12. Process and utility water requirements for cellulosic ethanol production processes via fermentation pathway (United States)

    The increasing need of additional water resources for energy production is a growing concern for future economic development. In technology development for ethanol production from cellulosic feedstocks, a detailed assessment of the quantity and quality of water required, and the ...

  13. Efficient ethanol recovery from yeast fermentation broth with integrated distillation-membrane process (United States)

    A hybrid process integrating vapor stripping with vapor compression and vapor permeation membrane separation, termed Membrane Assisted Vapor Stripping (MAVS), was evaluated for recovery and dehydration of ethanol from aqueous solution as an alternative to conventional distillatio...

  14. Efficient ethanol recovery from fermentation broths with integrated distillation-membrane process (United States)

    The energy demand of distillation-molecular sieve systems for ethanol recovery/dehydration can be significant, particularly for dilute solutions. An alternative process integrating vapor stripping (like a beer still) with vapor compression and a vapor permeation membrane separati...

  15. Enhancement of n-butanol production by in situ butanol removal using permeating-heating-gas stripping in acetone-butanol-ethanol fermentation. (United States)

    Chen, Yong; Ren, Hengfei; Liu, Dong; Zhao, Ting; Shi, Xinchi; Cheng, Hao; Zhao, Nan; Li, Zhenjian; Li, Bingbing; Niu, Huanqing; Zhuang, Wei; Xie, Jingjing; Chen, Xiaochun; Wu, Jinglan; Ying, Hanjie


    Butanol recovery from acetone-butanol-ethanol (ABE) fed-batch fermentation using permeating-heating-gas was determined in this study. Fermentation was performed with Clostridium acetobutylicum B3 in a fibrous bed bioreactor and permeating-heating-gas stripping was used to eliminate substrate and product inhibition, which normally restrict ABE production and sugar utilization to below 20 g/L and 60 g/L, respectively. In batch fermentation (without permeating-heating-gas stripping), C. acetobutylicum B3 utilized 60 g/L glucose and produced 19.9 g/L ABE and 12 g/L butanol, while in the integrated process 290 g/L glucose was utilized and 106.27 g/L ABE and 66.09 g/L butanol were produced. The intermittent gas stripping process generated a highly concentrated condensate containing approximately 15% (w/v) butanol, 4% (w/v) acetone, a small amount of ethanol (production.

  16. Cause analysis of the effects of acid-catalyzed steam-exploded corn stover prehydrolyzate on ethanol fermentation by Pichia stipitis CBS 5776. (United States)

    Zhu, Junjun; Yang, Jinlong; Zhu, Yuanyuan; Zhang, Lingling; Yong, Qiang; Xu, Yong; Li, Xin; Yu, Shiyuan


    The prehydrolyzate obtained from acid-catalyzed steam-exploded corn stover (ASC) mainly contains xylose and a number of inhibitory compounds that inhibit ethanol fermentation by Pichia stipitis. In this study, the effects of the ASC prehydrolyzate, specifically those of the carbohydrate-degradation products, lignin-degradation products (which were extracted from ASC prehydrolyzate using ethyl acetate), and six major phenolic compounds (added to pure-sugar media individually or in combination), on ethanol fermentation were investigated. Results indicate that the effects of the carbohydrate-degradation products were negligible (10 h delayed) compared with those of pure-sugar fermentation, whereas the effects of the lignin-degradation products were significant (52 h delayed). Meanwhile, the inhibitory effects of the major phenolic compounds were not caused by certain types of inhibitors, but were due to the synergistic effects of various inhibitors.

  17. Ethanol affects the development of sensory hair cells in larval zebrafish (Danio rerio.

    Directory of Open Access Journals (Sweden)

    Phillip M Uribe

    Full Text Available Children born to mothers with substantial alcohol consumption during pregnancy can present a number of morphological, cognitive, and sensory abnormalities, including hearing deficits, collectively known as fetal alcohol syndrome (FAS. The goal of this study was to determine if the zebrafish lateral line could be used to study sensory hair cell abnormalities caused by exposure to ethanol during embryogenesis. Some lateral line sensory hair cells are present at 2 days post-fertilization (dpf and are functional by 5 dpf. Zebrafish embryos were raised in fish water supplemented with varying concentrations of ethanol (0.75%-1.75% by volume from 2 dpf through 5 dpf. Ethanol treatment during development resulted in many physical abnormalities characteristic of FAS in humans. Also, the number of sensory hair cells decreased as the concentration of ethanol increased in a dose-dependent manner. The dye FM 1-43FX was used to detect the presence of functional mechanotransduction channels. The percentage of FM 1-43-labeled hair cells decreased as the concentration of ethanol increased. Methanol treatment did not affect the development of hair cells. The cell cycle markers proliferating cell nuclear antigen (PCNA and bromodeoxyuridine (BrdU demonstrated that ethanol reduced the number of sensory hair cells, as a consequence of decreased cellular proliferation. There was also a significant increase in the rate of apoptosis, as determined by TUNEL-labeling, in neuromasts following ethanol treatment during larval development. Therefore, zebrafish are a useful animal model to study the effects of hair cell developmental disorders associated with FAS.

  18. Wet oxidation treatment of organic household waste enriched with wheat straw for simultaneous saccharification and fermentation into ethanol

    DEFF Research Database (Denmark)

    Lissens, G.; Klinke, H.B.; Verstraete, W.;


    Organic municipal solid waste enriched with wheat straw was subjected to wet-oxidation as a pre-treatment for subsequent enzymatic conversion and fermentation into bio-ethanol. The effect of tempera (185-195degrees C), oxygen pressure (3-12) and sodium carbonate (0-2 g l(-1)) addition on enzymatic...... cellulose and hemicellulose convertibility was studied at a constant wet oxidation retention time of 10 minutes. An enzyme convertibility assay at high enzyme loading (25 filter paper unit (FPU) g(-1) dry solids (DS) added) showed that up to 78% of the cellulose and up to 68% of the hemicellulose...... in the treated waste could be converted into respectively hexose and pentose sugars compared to 46% for cellulose and 36% for hemicellulose in the raw waste. For all wet oxidation conditions tested, total carbohydrate recoveries were high (> 89%) and 44-66% of the original lignin could be converted into non...

  19. Plant extracts affect in vitro rumen microbial fermentation. (United States)

    Busquet, M; Calsamiglia, S; Ferret, A; Kamel, C


    Different doses of 12 plant extracts and 6 secondary plant metabolites were incubated for 24 h in diluted ruminal fluid with a 50:50 forage:concentrate diet. Treatments were: control (no additive), plant extracts (anise oil, cade oil, capsicum oil, cinnamon oil, clove bud oil, dill oil, fenugreek, garlic oil, ginger oil, oregano oil, tea tree oil, and yucca), and secondary plant metabolites (anethol, benzyl salicylate, carvacrol, carvone, cinnamaldehyde, and eugenol). Each treatment was supplied at 3, 30, 300, and 3,000 mg/L of culture fluid. At 3,000 mg/L, most treatments decreased total volatile fatty acid concentration, but cade oil, capsicum oil, dill oil, fenugreek, ginger oil, and yucca had no effect. Different doses of anethol, anise oil, carvone, and tea tree oil decreased the proportion of acetate and propionate, which suggests that these compounds may not be nutritionally beneficial to dairy cattle. Garlic oil (300 and 3,000 mg/L) and benzyl salicylate (300 and 3,000 mg/L) reduced acetate and increased propionate and butyrate proportions, suggesting that methane production was inhibited. At 3,000 mg/L, capsicum oil, carvacrol, carvone, cinnamaldehyde, cinnamon oil, clove bud oil, eugenol, fenugreek, and oregano oil resulted in a 30 to 50% reduction in ammonia N concentration. Careful selection and combination of these extracts may allow the manipulation of rumen microbial fermentation.

  20. Design of a lamella settler for biomass recycling in continuous ethanol fermentation process. (United States)

    Tabera, J; Iznaola, M A


    The design and application of a settler to a continuous fermentation process with yeast recycle were studied. The compact lamella-type settler was chosen to avoid large volumes associated with conventional settling tanks. A rationale of the design method is covered. The sedimentation area was determined by classical batch settling rate tests and sedimentation capacity calculation. Limitations on the residence time of the microorganisms in the settler, rather than sludge thickening considerations, was the approach employed for volume calculation. Fermentation rate tests with yeast after different sedimentation periods were carried out to define a suitable residence time. Continuous cell recycle fermentation runs, performed with the old and new sedimentation devices, show that lamella settler improves biomass recycling efficiency, being the process able to operate at higher sugar concentrations and faster dilution rates.

  1. Enzyme hydrolysis and ethanol fermentation of dilute ammonia pretreated energy cane. (United States)

    Aita, G A; Salvi, D A; Walker, M S


    This study is the first one ever to report on the use of high fiber sugarcane (a.k.a. energy cane) bagasse as feedstock for the production of cellulosic ethanol. Energy cane bagasse was pretreated with ammonium hydroxide (28% v/v solution), and water at a ratio of 1:0.5:8 at 160°C for 1h under 0.9-1.1 MPa. Approximately, 55% lignin, 30% hemicellulose, 9% cellulose, and 6% other (e.g., ash, proteins) were removed during the process. The maximum glucan conversion of dilute ammonia treated energy cane bagasse by cellulases was 87% with an ethanol yield (glucose only) of 23 g ethanol/100g dry biomass. The enzymatic digestibility was related to the removal of lignin and hemicellulose, perhaps due to increased surface area and porosity resulting in the deformation and swelling of exposed fibers as shown in the SEM pictures.

  2. Metabolic engineering of ammonium assimilation in xylose-fermenting Saccharomyces cerevisiae improves ethanol production. (United States)

    Roca, Christophe; Nielsen, Jens; Olsson, Lisbeth


    Cofactor imbalance impedes xylose assimilation in Saccharomyces cerevisiae that has been metabolically engineered for xylose utilization. To improve cofactor use, we modified ammonia assimilation in recombinant S. cerevisiae by deleting GDH1, which encodes an NADPH-dependent glutamate dehydrogenase, and by overexpressing either GDH2, which encodes an NADH-dependent glutamate dehydrogenase, or GLT1 and GLN1, which encode the GS-GOGAT complex. Overexpression of GDH2 increased ethanol yield from 0.43 to 0.51 mol of carbon (Cmol) Cmol(-1), mainly by reducing xylitol excretion by 44%. Overexpression of the GS-GOGAT complex did not improve conversion of xylose to ethanol during batch cultivation, but it increased ethanol yield by 16% in carbon-limited continuous cultivation at a low dilution rate.

  3. Non-severe thermochemical hydrolysis of stover from white corn and sequential enzymatic saccharification and fermentation to ethanol. (United States)

    Vargas-Tah, Alejandra; Moss-Acosta, Cessna L; Trujillo-Martinez, Berenice; Tiessen, Axel; Lozoya-Gloria, Edmundo; Orencio-Trejo, Montserrat; Gosset, Guillermo; Martinez, Alfredo


    A parametric study, with an initial load of 15%w/w of dry stover from white corn, was conducted to evaluate the sequential thermochemical hydrolysis (TH), enzymatic saccharification (ES) and fermentation of the whole slurry with ethanologenic Escherichia coli. The TH was designed to release the maximum amount of xylose with a concomitant formation of minimal amounts of furans. It was found that 29.0% or 93.2% of the xylan was recovered as free xylose at 130°C after 8 min in the presence of 1% or 2%w/w H2SO4 and produced only 0.06 or 0.44 g/L of total furans, respectively. After 24h of ES, 76.14-77.18 g/L of monosaccharides (pentoses and hexoses) were obtained. These slurries, which contained 0.03-0.26 g/L of total furans and 5.14-5.91 g/L of acetate, were fermented with 3.7 g/L of ethanologenic E. coli to produce 24.5-23.5 g/L of ethanol.

  4. Acetone-butanol-ethanol fermentation of corn stover by Clostridium species: present status and future perspectives. (United States)

    Li, Jianzheng; Baral, Nawa Raj; Jha, Ajay Kumar


    Sustainable vehicle fuel is indispensable in future due to worldwide depletion of fossil fuel reserve, oil price fluctuation and environmental degradation. Microbial production of butanol from renewable biomass could be one of the possible options. Renewable biomass such as corn stover has no food deficiency issues and is also cheaper in most of the agricultural based countries. Thus it can effectively solve the existing issue of substrate cost. In the last 30 years, a few of Clostridium strains have been successfully implemented for biobutanol fermentation. However, the commercial production is hindered due to their poor tolerance to butanol and inhibitors. Metabolic engineering of Clostridia strains is essential to solve above problems and ultimately enhance the solvent production. An effective and efficient pretreatment of raw material as well as optimization of fermentation condition could be another option. Furthermore, biological approaches may be useful to optimize both the host and pathways to maximize butanol production. In this context, this paper reviews the existing Clostridium strains and their ability to produce butanol particularly from corn stover. This study also highlights possible fermentation pathways and biological approaches that may be useful to optimize fermentation pathways. Moreover, challenges and future perspectives are also discussed.

  5. An experimental study on fermentative H₂ production from food waste as affected by pH. (United States)

    Cappai, G; De Gioannis, G; Friargiu, M; Massi, E; Muntoni, A; Polettini, A; Pomi, R; Spiga, D


    Batch dark fermentation experiments were performed on food waste and mixtures of food waste and wastewater activated sludge to evaluate the influence of pH on biological H2 production and compare the process performance with and without inoculum addition. The effect of a preliminary thermal shock treatment of the inoculum was also investigated as a means to harvest the hydrogenogenic biomass. The best performance in terms of both H2 generation potential and process kinetics was observed at pH=6.5 under all experimental conditions (no inoculum, and untreated or thermally treated inoculum added). H2 production from food waste was found to be feasible even without inoculum addition, although thermal pre-treatment of the inoculum notably increased the maximum production and reduced the lag phase duration. The analysis of the fermentation products indicated that the biological hydrogen production could be mainly ascribed to a mixed acetate/butyrate-type fermentation. However, the presence of additional metabolites in the digestate, including propionate and ethanol, also indicated that other metabolic pathways were active during the process, reducing substrate conversion into hydrogen. The plateau in H2 generation was found to mirror the condition at which soluble carbohydrates were depleted. Beyond this condition, homoacetogenesis probably started to play a role in the degradation process.

  6. Steam explosion treatment for ethanol production from branches pruned from pear trees by simultaneous saccharification and fermentation. (United States)

    Sasaki, Chizuru; Okumura, Ryosuke; Asada, Chikako; Nakamura, Yoshitoshi


    This study investigated the production of ethanol from unutilized branches pruned from pear trees by steam explosion pretreatment. Steam pressures of 25, 35, and 45 atm were applied for 5 min, followed by enzymatic saccharification of the extracted residues with cellulase (Cellic CTec2). High glucose recoveries, of 93.3, 99.7, and 87.1%, of the total sugar derived from the cellulose were obtained from water- and methanol-extracted residues after steam explosion at 25, 35, and 45 tm, respectively. These values corresponded to 34.9, 34.3, and 27.1 g of glucose per 100 g of dry steam-exploded branches. Simultaneous saccharification and fermentation experiments were done on water-extracted residues and water- and methanol-extracted residues by Kluyveromyces marxianus NBRC 1777. An overall highest theoretical ethanol yield of 76% of the total sugar derived from cellulose was achieved when 100 g/L of water- and methanol-washed residues from 35 atm-exploded pear branches was used as substrate.

  7. Improvement of hydrogen production via ethanol-type fermentation in an anaerobic down-flow structured bed reactor. (United States)

    Anzola-Rojas, Mélida del Pilar; Zaiat, Marcelo; De Wever, Heleen


    Although a novel anaerobic down-flow structured bed reactor has shown feasibility and stable performance for a long-term compared to other anaerobic fixed bed systems for continuous hydrogen production, the volumetric rates and yields have so far been too low. In order to improve the performance, an operation strategy was applied by organic loading rate (OLR) variation (12-96 g COD L(-1) d(-1)). Different volumetric hydrogen rates, and yields at the same OLR indicated that the system was mainly driven by the specific organic load (SOL). When SOL was kept between 3.8 and 6.2 g sucrose g(-1) VSS d(-1), the volumetric rates raised from 0.1 to 8.9 L H2 L(-1) d(-1), and the yields were stable around 2.0 mol H2 mol(-1) converted sucrose. Furthermore, hydrogen was produced mainly via ethanol-type fermentation, reaching a total energy conversion rate of 23.40 kJ h(-1) L(-1) based on both hydrogen and ethanol production.

  8. Simultaneous saccharification and fermentation of orange processing waste to ethanol using Kluyveromyces marxianus (United States)

    Citrus processing waste (CPW) from the production of citrus juices is a promising resource for the production of fuel ethanol. This waste, mainly peel, is rich in soluble sugars and polymeric carbohydrates. It has a very low lignin content and can be easily hydrolyzed by a mixture of pectinolytic, c...

  9. Efficient ethanol recovery from fermentation broths with integrated distillation-vapor permeation hybrid process (United States)

    The energy demand of distillation-molecular sieve systems for ethanol recovery/dehydration can be significant, particularly for dilute solutions. An alternative hybrid process integrating vapor stripping (like a beer still) with vapor compression and a vapor permeation membrane s...

  10. Continuous Ethanol Fermentation of Pretreated Lignocellulosic Biomasses, Waste Biomasses, Molasses and Syrup Using the Anaerobic, Thermophilic Bacterium Thermoanaerobacter italicus Pentocrobe 411.

    Directory of Open Access Journals (Sweden)

    Rasmus Lund Andersen

    Full Text Available Lignocellosic ethanol production is now at a stage where commercial or semi-commercial plants are coming online and, provided cost effective production can be achieved, lignocellulosic ethanol will become an important part of the world bio economy. However, challenges are still to be overcome throughout the process and particularly for the fermentation of the complex sugar mixtures resulting from the hydrolysis of hemicellulose. Here we describe the continuous fermentation of glucose, xylose and arabinose from non-detoxified pretreated wheat straw, birch, corn cob, sugar cane bagasse, cardboard, mixed bio waste, oil palm empty fruit bunch and frond, sugar cane syrup and sugar cane molasses using the anaerobic, thermophilic bacterium Thermoanaerobacter Pentocrobe 411. All fermentations resulted in close to maximum theoretical ethanol yields of 0.47-0.49 g/g (based on glucose, xylose, and arabinose, volumetric ethanol productivities of 1.2-2.7 g/L/h and a total sugar conversion of 90-99% including glucose, xylose and arabinose. The results solidify the potential of Thermoanaerobacter strains as candidates for lignocellulose bioconversion.

  11. Continuous Ethanol Fermentation of Pretreated Lignocellulosic Biomasses, Waste Biomasses, Molasses and Syrup Using the Anaerobic, Thermophilic Bacterium Thermoanaerobacter italicus Pentocrobe 411. (United States)

    Andersen, Rasmus Lund; Jensen, Karen Møller; Mikkelsen, Marie Just


    Lignocellosic ethanol production is now at a stage where commercial or semi-commercial plants are coming online and, provided cost effective production can be achieved, lignocellulosic ethanol will become an important part of the world bio economy. However, challenges are still to be overcome throughout the process and particularly for the fermentation of the complex sugar mixtures resulting from the hydrolysis of hemicellulose. Here we describe the continuous fermentation of glucose, xylose and arabinose from non-detoxified pretreated wheat straw, birch, corn cob, sugar cane bagasse, cardboard, mixed bio waste, oil palm empty fruit bunch and frond, sugar cane syrup and sugar cane molasses using the anaerobic, thermophilic bacterium Thermoanaerobacter Pentocrobe 411. All fermentations resulted in close to maximum theoretical ethanol yields of 0.47-0.49 g/g (based on glucose, xylose, and arabinose), volumetric ethanol productivities of 1.2-2.7 g/L/h and a total sugar conversion of 90-99% including glucose, xylose and arabinose. The results solidify the potential of Thermoanaerobacter strains as candidates for lignocellulose bioconversion.

  12. 不同初始pH值的乙醇发酵过程拉曼光谱分析%Raman Spectroscopic Analysis of Ethanol Fermentation at Various Initial pH Levels

    Institute of Scientific and Technical Information of China (English)

    覃赵军; 赖钧灼; 刘斌; 刘军贤; 王桂文


    pH值是影响酵母乙醇发酵的重要因素.应用拉曼光谱初步分析不同初始pH值对乙醇发酵过程的影响.结果显示:1)在3.0、4.5、6.5三个不同初始pH值的培养基中,pH4.5下乙醇产量最高,pH 3.0下最低.2)在发酵的前15h,不同初始pH值下的酵母细胞生物大分子的拉曼信号变化波动大;后期,pH3.0下胞内脂类和蛋白质的拉曼信号最强,pH 6.5最弱;显示在低pH值环境下部分底物可能被转化为胞内储藏物质.3)主成分分析显示,pH值对酵母细胞生理状态的影响从发酵的初始阶段就开始;1440 cm-1和1600 cm-1峰一直是影响主成分PC1、PC2、PC3分值的主要特征峰;说明pH环境可能影响了酵母细胞的脂类物质合成和细胞的呼吸代谢,进而影响了底物的代谢方向和产物的合成.结果表明,拉曼光谱和单细胞分析可以用于剖析微生物发酵过程的生理机制,为乙醇发酵提供全新的参考信息.%The pH level is a prominent factor affects the ethanol fermentation. Optical tweezers Raman spectroscopy is used to analyze the process of ethanol fermentation at the initial pH levels of 3.0, 4.5, 6.5. Major results from this work are as follows: 1) The pH 4. 5 level get the highest ethanol production and the pH 3.0 get the lowest one. 2) Raman intensities of bio-macromolecules of yeast cells at all pH levels exhibite dramatic changes in the first 15 hours. However, at the later stage of the fermentation, the pH 3. 0 level displayes strong Raman intensities of intracellular lipids and proteins while pH 6. 5 level shows weak. This indicates that a portion of substrate may be transformed into intracellular storage material by yeast cells at lower pH level. 3) Principal component analysis reveals that fermentation pH influences the physiological status of yeast cells from the beginning of fermentation, and bands 1440 cm-1 and 1600 cm-1 are the prominent contributors to the component loadings in different

  13. Bio-conversion of apple pomace into ethanol and acetic acid: Enzymatic hydrolysis and fermentation. (United States)

    Parmar, Indu; Rupasinghe, H P Vasantha


    Enzymatic hydrolysis of cellulose present in apple pomace was investigated using process variables such as enzyme activity of commercial cellulase, pectinase and β-glucosidase, temperature, pH, time, pre-treatments and end product separation. The interaction of enzyme activity, temperature, pH and time had a significant effect (Pfermented using Saccharomyces cerevisae yielding 19.0g ethanol/100g DM. Further bio-conversion using Acetobacter aceti resulted in the production of acetic acid at a concentration of 61.4g/100g DM. The present study demonstrates an improved process of enzymatic hydrolysis of apple pomace to yield sugars and concomitant bioconversion to produce ethanol and acetic acid.

  14. Optimization of factors affecting the production of biodiesel from crude palm kernel oil and ethanol

    Directory of Open Access Journals (Sweden)

    David K. Kuwornoo, Julius C. Ahiekpor


    Full Text Available Biodiesel, an alternative diesel fuel made from renewable sources such as vegetable oils and animal fats, has been identified by government to play a key role in the socio-economic development of Ghana. The utilization of biodiesel is expected to be about 10% of the total liquid fuel mix of the country by the year 2020. Despite this great potential and the numerous sources from which biodiesel could be developed in Ghana, studies on the sources of biodiesel and their properties as a substitute for fossil diesel have tended to be limited to Jatropha oil. This paper, however, reports the parameters that influences the production of biodiesel from palm kernel oil, one of the vegetable oils obtained from oil palm which is the highest vegetable oil source in Ghana. The parameters studied are; mass ratio of ethanol to oil, reaction temperature, catalyst concentration, and reaction time using completely randomized 24 factorial design. Results indicated that ethanol to oil mass ratio, catalyst concentration and reaction time were the most important factors affecting the ethyl ester yield. There was also an interaction effect between catalyst and time and ethanol- oil ratio and time on the yield. Accordingly, the optimal conditions for the production of ethyl esters from crude palm kernel oil were determined as; 1:5 mass ratio of ethanol to oil, 1% catalyst concentration by weight of oil, 90 minutes reaction time at a temperature of 30 oC.

  15. Metabolic Engineering of Ammonium Assimilation in Xylose-Fermenting Saccharomyces cerevisiae Improves Ethanol Production


    Roca, Christophe; Nielsen, Jens; Olsson, Lisbeth


    Cofactor imbalance impedes xylose assimilation in Saccharomyces cerevisiae that has been metabolically engineered for xylose utilization. To improve cofactor use, we modified ammonia assimilation in recombinant S. cerevisiae by deleting GDH1, which encodes an NADPH-dependent glutamate dehydrogenase, and by overexpressing either GDH2, which encodes an NADH-dependent glutamate dehydrogenase, or GLT1 and GLN1, which encode the GS-GOGAT complex. Overexpression of GDH2 increased ethanol yield from...

  16. Simultaneous saccharification and fermentation of starch for ethanol production in a fluidized-bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Nghiem, N.P.; Davison, B.H. [Oak Ridge National Lab., TN (United States); Sun, M.Y.; Bienkowski, P.R. [Univ. of Tennessee, Knoxville, TN (United States)


    Immobilized Zymomonas mobilis has been used to produce ethanol from glucose in fluidized-bed reactor at volumetric productivity as high as 60 g/L-h and theoretical yield. This research was extended to study the production of ethanol from starch. The bacteria were co-immobilized with an industrial glucoamylase within small uniform beads (2 to 2.5 mm diameter) of k-carrageenan. The reactor was a glass column of 1.2 m in length with a uniform 2.54 cm diameter. The substrate included a commercially available maltodextrin and a soluble starch solution which was produced by hydrolysis of ground corn meals using amylase under the conditions commonly used in an industrial process. Light steep water was used as the complex nutrient source. Statistical experimental design was used to study the effects of substrate concentration and feed rate on ethanol yield and reactor productivity. The experiments were performed at 30{degrees}C and pH 5. The substrate concentration ranged from 93 to 2.7 g/L and the feed rates from 6.6 to 26.7 mL/min. The results of these studies will be discussed.

  17. Co-expression of TAL1 and ADH1 in recombinant xylose-fermenting Saccharomyces cerevisiae improves ethanol production from lignocellulosic hydrolysates in the presence of furfural. (United States)

    Hasunuma, Tomohisa; Ismail, Ku Syahidah Ku; Nambu, Yumiko; Kondo, Akihiko


    Lignocellulosic biomass dedicated to bioethanol production usually contains pentoses and inhibitory compounds such as furfural that are not well tolerated by Saccharomyces cerevisiae. Thus, S. cerevisiae strains with the capability of utilizing both glucose and xylose in the presence of inhibitors such as furfural are very important in industrial ethanol production. Under the synergistic conditions of transaldolase (TAL) and alcohol dehydrogenase (ADH) overexpression, S. cerevisiae MT8-1X/TAL-ADH was able to produce 1.3-fold and 2.3-fold more ethanol in the presence of 70 mM furfural than a TAL-expressing strain and a control strain, respectively. We also tested the strains' ability by mimicking industrial ethanol production from hemicellulosic hydrolysate containing fermentation inhibitors, and ethanol production was further improved by 16% when using MT8-1X/TAL-ADH compared to the control strain. Transcript analysis further revealed that besides the pentose phosphate pathway genes TKL1 and TAL1, ADH7 was also upregulated in response to furfural stress, which resulted in higher ethanol production compared to the TAL-expressing strain. The improved capability of our modified strain was based on its capacity to more quickly reduce furfural in situ resulting in higher ethanol production. The co-expression of TAL/ADH genes is one crucial strategy to fully utilize undetoxified lignocellulosic hydrolysate, leading to cost-competitive ethanol production.

  18. Fermentation conditions that affect clavulanic acid production in Streptomyces clavuligerus: a systematic review

    Directory of Open Access Journals (Sweden)

    Hooi-Leng eSer


    Full Text Available The β-lactamase inhibitor, clavulanic acid is frequently used in combination with β-lactam antibiotics to treat a wide spectrum of infectious diseases. Clavulanic acid prevents drug resistance by pathogens against these β-lactam antibiotics by preventing the degradation of the β-lactam ring, thus ensuring eradication of these harmful microorganisms from the host. This systematic review provides an overview on the fermentation conditions that affect the production of clavulanic acid in the firstly described producer, Streptomyces clavuligerus. A thorough search was conducted using predefined terms in several electronic databases (PubMed, Medline, ScienceDirect, EBSCO, from database inception to June 30th 2015. Studies must involve wild-type Streptomyces clavuligerus, and full texts needed to be available. A total of 29 eligible articles were identified. Based on the literature, several factors were identified that could affect the production of clavulanic acid in S. clavuligerus. The addition of glycerol or other vegetable oils (e.g. olive oil, corn oil could potentially affect clavulanic acid production. Furthermore, some amino acids such as arginine and ornithine, could serve as potential precursors to increase clavulanic acid yield. The comparison of different fermentation systems revealed that fed-batch fermentation yields higher amounts of clavulanic acid as compared to batch fermentation, probably due to the maintenance of substrates and constant monitoring of certain entities (such as pH, oxygen availability, etc.. Overall, these findings provide vital knowledge and insight that could assist media optimization and fermentation design for clavulanic acid production in S. clavuligerus.

  19. Fermentation Conditions that Affect Clavulanic Acid Production in Streptomyces clavuligerus: A Systematic Review. (United States)

    Ser, Hooi-Leng; Law, Jodi Woan-Fei; Chaiyakunapruk, Nathorn; Jacob, Sabrina Anne; Palanisamy, Uma Devi; Chan, Kok-Gan; Goh, Bey-Hing; Lee, Learn-Han


    The β-lactamase inhibitor, clavulanic acid is frequently used in combination with β-lactam antibiotics to treat a wide spectrum of infectious diseases. Clavulanic acid prevents drug resistance by pathogens against these β-lactam antibiotics by preventing the degradation of the β-lactam ring, thus ensuring eradication of these harmful microorganisms from the host. This systematic review provides an overview on the fermentation conditions that affect the production of clavulanic acid in the firstly described producer, Streptomyces clavuligerus. A thorough search was conducted using predefined terms in several electronic databases (PubMed, Medline, ScienceDirect, EBSCO), from database inception to June 30th 2015. Studies must involve wild-type Streptomyces clavuligerus, and full texts needed to be available. A total of 29 eligible articles were identified. Based on the literature, several factors were identified that could affect the production of clavulanic acid in S. clavuligerus. The addition of glycerol or other vegetable oils (e.g., olive oil, corn oil) could potentially affect clavulanic acid production. Furthermore, some amino acids such as arginine and ornithine, could serve as potential precursors to increase clavulanic acid yield. The comparison of different fermentation systems revealed that fed-batch fermentation yields higher amounts of clavulanic acid as compared to batch fermentation, probably due to the maintenance of substrates and constant monitoring of certain entities (such as pH, oxygen availability, etc.). Overall, these findings provide vital knowledge and insight that could assist media optimization and fermentation design for clavulanic acid production in S. clavuligerus.

  20. Application of Phytase in Corn Grain-to- ethanol Fermentation%植酸酶在玉米酒精发酵中的应用研究

    Institute of Scientific and Technical Information of China (English)

    李娜; 吕伟民; 赵姗姗; 夏海华


      探讨植酸酶在酒精发酵中的应用。实验室小试结果表明:在糖化时加入植酸酶,添加量为每克原料11个单位,作用 pH 为4.5,发酵温度为58~60℃,淀粉出酒率可提高1.5%,发酵周期可缩短4h。%The application of phytase in ethanol fermentation was discussed. The experimental results on laboratory scale showed that the ethanol yield was increased by 1.5% and the fermentation period was shorted for 4 hours, when 11u phytase per gram raw material was added under the pH 4.5 and temperature at 58-60℃ during saccharification.

  1. Ethanol fermentation characteristics of thermotolerant Issatchenkia orientalis%耐高温东方伊萨酵母乙醇发酵特性

    Institute of Scientific and Technical Information of China (English)

    王风芹; 汪媛媛; 陶西; 张瑞; 谢慧; 宋安东


    As a renewable and clean energy, bio-ethanol has been received widespread attention in recent years. Ethanol fermentation at high temperature can reduce the consumption of cooling water and energy in the process of fermentation, it also solve the problems caused by saccharification and uncontrolled fermentation temperature, resulting in the simultaneous saccharification and fermentation of cellulosic ethanol. Therefore, the fermentation period can be shorten and the production cost be reduced. A thermotolerant yeast strain HN-1 isolated from rotting tobacco leaves was identified and its ethanol fermentation characteristics was investigated in this study. The phylogenetic analysis indicated that phylogenetic strain HN-1 behaved likeIssatchenkia orientalis.This strain useed glucose and D-fructose but could not use xylose, maltose, lactose, sucrose, starch and cellobiose as sole carbon source to produce ethanol. When HN-1 was cultivated in 50 g/L glucose liquid medium, the highest biomass was obtained at 35 and 38℃. Increasing the cultivation temperature to 42 and 45℃ decreased the biomass growth and intensified the cell death. There was no major difference between ethanol productions (21.43~23.12 g/L) fermented at 35~45℃ from 50 g/L glucose. When increasing the fermentation temperature, the ethanol productivity was increased from 0.31 g/(L·h) at 35℃ to 0.65 g/(L·h) at 45℃ after 24h fermentation. The fermentation time was shortened. When the fermentation was conducted at 38℃, 28.77, 43.21, 58.19 and 59.53 g/L ethanol were produced from 60, 90, 120 and 150 g/L glucose with yields of 0.457, 0.468, 0.460 and 0.386 g/g and productivities of 0.38, 0.39, 0.48 and 0.40 g/(L·h) The results also indicated that fed batch fermentation could not enhance the ethanol production. Strain HN-1 could utilize corn straw hydrolysate with 43.08 g/L glucose and 27.13 g/L xylose to produce 20.74 g/L ethanol. The glucose conversion rate was 0.468 g/g, which was 91.6% of the

  2. Hybrid Neural Network Model of an Industrial Ethanol Fermentation Process Considering the Effect of Temperature (United States)

    Mantovanelli, Ivana C. C.; Rivera, Elmer Ccopa; da Costa, Aline C.; Filho, Rubens Maciel

    In this work a procedure for the development of a robust mathematical model for an industrial alcoholic fermentation process was evaluated. The proposed model is a hybrid neural model, which combines mass and energy balance equations with functional link networks to describe the kinetics. These networks have been shown to have a good nonlinear approximation capability, although the estimation of its weights is linear. The proposed model considers the effect of temperature on the kinetics and has the neural network weights reestimated always so that a change in operational conditions occurs. This allow to follow the system behavior when changes in operating conditions occur.

  3. A mathematical model of ethanol fermentation from cheese whey. II. Simulation and comparison with experimental data

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chen-Jen; Bajpai, R.K. [Univ. of Missouri, Columbia, MO (United States)


    A cybernetic model for microbial growth on mixed substrates was used to simulate the anaerobic fermentation of cheese whey and multiple sugars in semisynthetic media by Kluyveromyces marxianus CBS 397. The model simulations quite successfully predicted the observed behavior in batch and during transients in continuous operation, in single-substrate systems as well as in media involving multiple substrates, and in semisynthetic and reconstituted cheese whey solutions. The results of simulations and their comparison with the experimental data are presented. 7 refs., 11 figs., 2 tabs.

  4. Starch hydrolysis and its effect on product yield and microbial contamination in yeast ethanol fermentation. (United States)

    Czarnecki, Z; Grajek, W


    The influence of temperature and incubation time on starch gelatinization in wheat, rye and corn grain were studied. Rye starch was the most susceptlble to enzyme hydrolysls. Heat treatment of ground grain during starch gelatinlzation significantly reduced microblal contamination. In the batch fermentation of wheat, a high sugar utillization ranged from 92 to 94%. The highest alcohol yield was 65% from rye starch. The results obtained show that the high pressure cooking used for mash preparation can be replaced successfully by low temperature treatment.

  5. The ultimate ethanol: Technoeconomic evaluation of ethanol manufacture, comparing yeast vs Zymomonas bacterium fermentations. [Zymomonas mobilis:a5; Saccharomyces cerevisiae:a6

    Energy Technology Data Exchange (ETDEWEB)

    Busche, R.M. (Bio En-Gene-Er Associates, Inc., Wilmington, DE (United States)); Scott, C.D.; Davison, B.H. (Oak Ridge National Lab., TN (United States)); Lynd, L.R. (Dartmouth Coll., Hanover, NH (United States))


    If ethanol could be produced at a low enough price to serve as the precursor to ethylene and butadiene, it and its derivatives could account for 159 billion lb, or 50% of the US production of 316 billion lb of synthetic organic chemicals, presently valued at $113 billion. This use would consume 3.4 billion bu of corn, or {approximately}40% of the corn crop. This study evaluates advance process engineering and genetic engineering techniques that could generate savings and reduce production costs. The most rewarding development strategy appears to be to demonstrate at pilot scale the use of immobilized Zymomonas mobilis bacteria in a fluidized-bed bioreactor operating in a continuous mode over an extended period of time. Throughput should be adjusted to control product concentration at {approximately}100 g/L (i.e., as close to the threshold of inhibition as possible). There appears to be no inherent design limitation to effect the engineering improvements required in the advanced process operation. The above scenario assumes that the presently available, product-inhibited organisms would be used. In a longer-term, more difficult research effort, it might be possible to reduce or eliminate product inhibition. As a result, price would be reduced further to $1.75 for the Zymomonas system or $1.85 for the yeast fermentation. It is recommended that the engineering proveout of the advanced process be continued at a pilot scale and that a laboratory program aimed at reducing product inhibition and/or increasing specific productivity be initiated. 49 refs., 11 figs., 19 tabs.

  6. Impact of zinc supplementation on the improved fructose/xylose utilization and butanol production during acetone-butanol-ethanol fermentation. (United States)

    Wu, You-Duo; Xue, Chuang; Chen, Li-Jie; Bai, Feng-Wu


    Lignocellulosic biomass and dedicated energy crops such as Jerusalem artichoke are promising alternatives for biobutanol production by solventogenic clostridia. However, fermentable sugars such as fructose or xylose released from the hydrolysis of these feedstocks were subjected to the incomplete utilization by the strains, leading to relatively low butanol production and productivity. When 0.001 g/L ZnSO4·7H2O was supplemented into the medium containing fructose as sole carbon source, 12.8 g/L of butanol was achieved with butanol productivity of 0.089 g/L/h compared to only 4.5 g/L of butanol produced with butanol productivity of 0.028 g/L/h in the control without zinc supplementation. Micronutrient zinc also led to the improved butanol production up to 8.3 g/L derived from 45.2 g/L xylose as sole carbon source with increasing butanol productivity by 31.7%. Moreover, the decreased acids production was observed under the zinc supplementation condition, resulting in the increased butanol yields of 0.202 g/g-fructose and 0.184 g/g-xylose, respectively. Similar improvements were also observed with increasing butanol production by 130.2 % and 8.5 %, butanol productivity by 203.4% and 18.4%, respectively, in acetone-butanol-ethanol fermentations from sugar mixtures of fructose/glucose (4:1) and xylose/glucose (1:2) simulating the hydrolysates of Jerusalem artichoke tubers and corn stover. The results obtained from transcriptional analysis revealed that zinc may have regulatory mechanisms for the sugar transport and metabolism of Clostridium acetobutylicum L7. Therefore, micronutrient zinc supplementation could be an effective way for economic development of butanol production derived from these low-cost agricultural feedstocks.

  7. Rapid analysis of formic acid, acetic acid, and furfural in pretreated wheat straw hydrolysates and ethanol in a bioethanol fermentation using atmospheric pressure chemical ionisation mass spectrometry

    Directory of Open Access Journals (Sweden)

    Smart Katherine A


    Full Text Available Abstract Atmospheric pressure chemical ionisation mass spectrometry (APCI-MS offers advantages as a rapid analytical technique for the quantification of three biomass degradation products (acetic acid, formic acid and furfural within pretreated wheat straw hydrolysates and the analysis of ethanol during fermentation. The data we obtained using APCI-MS correlated significantly with high-performance liquid chromatography analysis whilst offering the analyst minimal sample preparation and faster sample throughput.

  8. Acetone-butanol-ethanol (ABE) fermentation using Clostridium acetobutylicum XY16 and in situ recovery by PDMS/ceramic composite membrane. (United States)

    Wu, Hao; Chen, Xiao-Peng; Liu, Gong-Ping; Jiang, Min; Guo, Ting; Jin, Wan-Qin; Wei, Ping; Zhu, Da-Wei


    PDMS/ceramic composite membrane was directly integrated with acetone-butanol-ethanol (ABE) fermentation using Clostridium acetobutylicum XY16 at 37 °C and in situ removing ABE from fermentation broth. The membrane was integrated with batch fermentation, and approximately 46 % solvent was extracted. The solvent in permeates was 118 g/L, and solvent productivity was 0.303 g/(L/h), which was approximately 33 % higher compared with the batch fermentation without in situ recovery. The fed-batch fermentation with in situ recovery by pervaporation continued for more than 200 h, 61 % solvent was extracted, and the solvent in penetration was 96.2 g/L. The total flux ranged from 0.338 to 0.847 kg/(m(2)/h) and the separation factor of butanol ranged from 5.1 to 27.1 in this process. The membrane was fouled by the active fermentation broth, nevertheless the separation performances were partially recovered by offline membrane cleaning, and the solvent productivity was increased to 0.252 g/(L/h), which was 19 % higher compared with that in situ recovery process without membrane cleaning.

  9. In vitro inhibitory effect on pancreatic lipase activity of subfractions from ethanol extracts of fermented Oats (Avena sativa L.) and synergistic effect of three phenolic acids. (United States)

    Cai, Shengbao; Wang, Ou; Wang, Mengqian; He, Jianfeng; Wang, Yong; Zhang, Di; Zhou, Feng; Ji, Baoping


    The purpose of the present work is to study the pancreatic lipase inhibitory effects of different subfractions (n-hexane, ethyl acetate (EA), n-butanol, and water) from ethanol extracts of nonfermented and fungi-fermented oats and to delineate the interactions of three primary phenolic acids in the EA subfractions. The EA subfraction showed the highest inhibitory effect on pancreatic lipase activity at 1.5 mg/mL compared to the other subfractions, regardless of whether the oats were fermented. Meanwhile, both of the EA subfractions of two fungi-fermented oats demonstrated more effective inhibitory activity than that of nonfermented oats. A positive correlation between the total phenolics content and inhibitory activity was found. The inhibitory ability of the EA subfraction from nonfermented or fermented oats also displayed a dose-dependent effect. The standards of caffeic, ferulic, and p-coumaric acids, mainly included in EA subfractions of fermented oats, also displayed a dose-dependent inhibitory effect. A synergistic effect of each binary combination of p-coumaric, ferulic, and caffeic acids was observed, especially at 150.0 μg/mL. Those results indicate that fungi-fermented oats have a more effective inhibitory ability on pancreatic lipase and polyphenols may be the most effective component and could be potentially used for dietary therapy of obesity.

  10. Reuse of Enzymatic Hydrolyzed Waste Liquid of Corn Based Ethanol Fermentation%玉米酒精糟液经酶水解后的回配利用

    Institute of Scientific and Technical Information of China (English)



    The waste liquid from ethanol fermentation was centrifuged.And then the complex enzyme,Fhm-5 was added for hydrolysis.The hydrolysate was reused for proportioning as nutrient broth.The utilization of the raw material was improved.Per unit of water consumption and volume of sewage to be treated were reduced.The fermentation time was shortened.The economic benefit of corn based ethanol fermentation was improved.To produce one ton of ethanol three tons of corn were required,and approximately 12 cubic meters of waste liquor were discharged.%酒精糟液经离心分离,并通过添加复合酶Fhm-5水解后作为营养液回用于配料的重新利用,提高了原料利用率,降低了水的单耗和污水处理量,缩短了发酵周期,提高了玉米酒精的经济效益。每生产1吨酒精需3吨玉米,排出糟液约为12m3。

  11. 通过抑制酿酒酵母乙醇发酵中的甘油产率提高乙醇产率%Improve Ethanol Yield Through Minimizing Glycerol Yield in Ethanol Fermentation of Saccharomyces cerevisiae

    Institute of Scientific and Technical Information of China (English)

    张爱利; 陈洵


    In ethanol fermentation of Saccharomyces cerevisiae (S.cerevisiae),glycerol is one of t11e main by-products.The purpose of this investigation was to increase ethanol yield through minimizing glycerol yield by using mutants in which FPSl encoding a channel protein that mediates glycerol export and GPD2 encoding one of glycerol-3-phosphate dehydrogenase were knocked-out using one-step gene replacement.GLTl and GLNl that encode glutamate synthase and glutamine synthetase,respectively,were overexpressed using two-step gene replacement in fps1△Agpd2△ mutant.The fermentation properties of ZAL69(fps1△::JLEU2 gpd2△::URA3)and ZAL808(fps1△::LEU2 gpd2△::URA3 PPGKI-GL71 PPGKI-GLNI)under microaerobic conditions were investigated and compared with those of wild type(DC124).Consumption of glucose,yield of ethanol,yield of glycerol,acetic acid,and pyruvic acid were monitored.Compared with wild type.the ethanol yield of ZAL69 and ZAL808 were improved by 13.17%and 6.66%,respectively,whereas glycerol yield decreased by 37.4%and 41.7%.Meanwhile,acetic acid yield and pyruvic acid yield decreased dramatically compared to wild type.Our results indicate that FPS1 and GPD2 deletion of S.cerevisiae resulted in reduced glycerol yield and increased ethanol yield.but simultaneous overexpression of GLTl and GLN1-in fps1△gpd2△ mutant did not have a higher ethanol yield thall fps1△gpd2△ mutant.

  12. Jilebi 2: Flowability, pourability and pH of batter as affected by fermentation. (United States)

    Chakkaravarthi, A; Kumar, H N Punil; Bhattacharya, Suvendu


    Fermentation of batter is an integral part of the preparation of jilebi, a traditional ready-to-eat sweet product of Indian sub-continent. The flowability and pourability of batter are crucial for forming jilebi strands during frying. Flowability and pourability have been determined from simulation studies based on the movement of batter on an inclined surface and the exit from an orifice, respectively; simple gadgets have been designed to determine these two characteristics along with providing the definitions. Response surface experimental design consisting of moisture content (50-65%), amount of added curd (0-10%) and time of fermentation (0-24 h) has been employed. The response functions are pH, flowability and pourability. Strong interaction effects of added curd and time of fermentation on the response functions have been observed. An increase in added curd and time of fermentation decreases pH in a curvilinear manner as both linear and quadratic effects are significant (p ≤ 0.01). Moisture content has a non-significant effect on pH but markedly affects the flowability and pourability of batter. Flowability and pourability decreases when there is an increase in consistency index or apparent viscosity.

  13. Enhancing clostridial acetone-butanol-ethanol (ABE) production and improving fuel properties of ABE-enriched biodiesel by extractive fermentation with biodiesel. (United States)

    Li, Qing; Cai, Hao; Hao, Bo; Zhang, Congling; Yu, Ziniu; Zhou, Shengde; Chenjuan, Liu


    The extractive acetone-butanol-ethanol (ABE) fermentations of Clostridium acetobutylicum were evaluated using biodiesel as the in situ extractant. The biodiesel preferentially extracted butanol, minimized product inhibition, and increased production of butanol (from 11.6 to 16.5 g L⁻¹) and total solvents (from 20.0 to 29.9 g L⁻¹) by 42% and 50%, respectively. The fuel properties of the ABE-enriched biodiesel obtained from the extractive fermentations were analyzed. The key quality indicators of diesel fuel, such as the cetane number (increased from 48 to 54) and the cold filter plugging point (decreased from 5.8 to 0.2 °C), were significantly improved for the ABE-enriched biodiesel. Thus, the application of biodiesel as the extractant for ABE fermentation would increase ABE production, bypass the energy intensive butanol recovery process, and result in an ABE-enriched biodiesel with improved fuel properties.

  14. Characterization of isolated biomass of the fermentation processes for ethanol production for use as biofuels; Caracterizacao da biomassa isolada de processos fermentativos de producao de etanol para uso como biocombustiveis

    Energy Technology Data Exchange (ETDEWEB)

    Steckelberg, Claudia; Andrietta, Maria da Graca Stupiello; Andrietta, Silvio Roberto [Universidade Estadual de Campinas (CPQBA/UNICAMP), SP (Brazil). Centro Pluridisciplinar de Pesquisas Quimicas, Biologicas e Agricolas. Div. de Biotecnologia e Processos], Email:


    This study has had the purpose of enhancing the knowledge on the dominant strains of ethanol fermentation process biomass to use as bio fuel. The attributes studied were: numerical taxonomy (Griffits, 1981) and fermentative performance. The results have showed that all strains have presented good fermentative characteristics. All strains have been classified as Saccharomyces. In this genus were found the follow species: chevalieri, coreanus cerevisiae. If the classification according Barnet (1992) is considered, all of them are representative of S. cerevisiae. (author)

  15. Methods to improve ethanol content of sugarcane juice fermentation%提高甘蔗汁酒精发酵酒度的实验

    Institute of Scientific and Technical Information of China (English)

    易弋; 容元平; 程谦伟; 黎娅; 伍时华


    In order to improve the ethanol content of sugarcane juice fermentation, the sugarcane juice was concentrated or mixed with sucrose, molasses and cassava hydrolysate respectively for fermentation.The results showed when the concentration of initial sugar was about 18%-20% (m/v),the final ethanol concentration about 11% (v/v)and fermentation efficiency above 90% would be obtained by the first three methods.The fermentation efficiency would be lower by the last method because the strain could not use sucrose and amylose simultaneously.%为了提高甘蔗汁酒精发酵的酒度,选择甘蔗汁浓缩、以及向甘蔗汁中添加蔗糖、糖蜜和木薯粉水解液4种方法进行酒精发酵。实验结果表明,当初始总糖在18%-20%(m/v)范围时,使用前三种方法都能获得11%(v/v)左右的发酵酒精度和90%以上的发酵效率;最后一种方法由于菌种不能同时利用蔗糖和淀粉糖而导致发酵效率偏低。

  16. Kinetic models for batch ethanol production from sweet sorghum juice under normal and high gravity fermentations: Logistic and modified Gompertz models. (United States)

    Phukoetphim, Niphaphat; Salakkam, Apilak; Laopaiboon, Pattana; Laopaiboon, Lakkana


    The aim of this study was to model batch ethanol production from sweet sorghum juice (SSJ), under normal gravity (NG, 160g/L of total sugar) and high gravity (HG, 240g/L of total sugar) conditions with and without nutrient supplementation (9g/L of yeast extract), by Saccharomyces cerevisiae NP 01. Growth and ethanol production increased with increasing initial sugar concentration, and the addition of yeast extract enhanced both cell growth and ethanol production. From the results, either logistic or a modified Gompertz equation could be used to describe yeast growth, depending on information required. Furthermore, the modified Gompertz model was suitable for modeling ethanol production. Both the models fitted the data very well with coefficients of determination exceeding 0.98. The results clearly showed that these models can be employed in the development of ethanol production processes using SSJ under both NG and HG conditions. The models were also shown to be applicable to other ethanol fermentation systems employing pure and mixed sugars as carbon sources.

  17. Ethanol production by a new pentose-fermenting yeast strain, Scheffersomyces stipitis UFMG-IMH 43.2, isolated from the Brazilian forest. (United States)

    Ferreira, Adriana D; Mussatto, Solange I; Cadete, Raquel M; Rosa, Carlos A; Silva, Silvio S


    The ability of a recently isolated Scheffersomyces stipitis strain (UFMG-IMH 43.2) to produce ethanol from xylose was evaluated. For the assays, a hemicellulosic hydrolysate produced by dilute acid hydrolysis of sugarcane bagasse was used as the fermentation medium. Initially, the necessity of adding nutrients (MgSO(4)·7H(2)O, yeast extract and/or urea) to this medium was verified, and the yeast extract supplementation favoured ethanol production by the yeast. Then, in a second stage, assays under different initial xylose and cell concentrations, supplemented or not with yeast extract, were performed. All these three variables showed significant (p UFMG-IMH 43.2 was demonstrated to be a yeast strain with potential for use in xylose conversion to ethanol. The establishment of the best fermentation conditions was also proved to be of great importance to increasing the product formation by this yeast strain. These findings open up new perspectives for the establishment of a feasible technology for ethanol production from hemicellulosic hydrolysates.

  18. Growth and ethanol fermentation ability on hexose and pentose sugars and glucose effect under various conditions in thermotolerant yeast Kluyveromyces marxianus

    Energy Technology Data Exchange (ETDEWEB)

    Rodrussamee, Nadchanok; Hirata, Katsushi; Suprayogi [Yamaguchi Univ., Ube (Japan). Graduate School of Medicine; Lertwattanasakul, Noppon; Kosaka, Tomoyuki [Yamaguchi Univ. (Japan). Faculty of Agriculture; Limtong, Savitree [Kasetsart Univ., Bangkok (Thailand). Faculty of Science; Yamada, Mamoru [Yamaguchi Univ., Ube (Japan). Graduate School of Medicine; Yamaguchi Univ. (Japan). Faculty of Agriculture


    Ethanol fermentation ability of the thermotolerant yeast Kluyveromyces marxianus, which is able to utilize various sugars including glucose, mannose, galactose, xylose, and arabinose, was examined under shaking and static conditions at high temperatures. The yeast was found to produce ethanol from all of these sugars except for arabinose under a shaking condition but only from hexose sugars under a static condition. Growth and sugar utilization rate under a static condition were slower than those under a shaking condition, but maximum ethanol yield was slightly higher. Even at 40 C, a level of ethanol production similar to that at 30 C was observed except for galactose under a static condition. Glucose repression on utilization of other sugars was observed, and it was more evident at elevated temperatures. Consistent results were obtained by the addition of 2-deoxyglucose. The glucose effect was further examined at a transcription level, and it was found that KmGAL1 for galactokinase and KmXYL1 for xylose reductase for galactose and xylose/arabinose utilization, respectively, were repressed by glucose at low and high temperatures, but KmHXK2 for hexokinase was not repressed. We discuss the possible mechanism of glucose repression and the potential for utilization of K. marxianus in high-temperature fermentation with mixed sugars containing glucose. (orig.)

  19. Improved growth and ethanol fermentation of Saccharomyces cerevisiae in the presence of acetic acid by overexpression of SET5 and PPR1. (United States)

    Zhang, Ming-Ming; Zhao, Xin-Qing; Cheng, Cheng; Bai, Feng-Wu


    To better understand the contribution of zinc-finger proteins to environmental stress tolerance, particularly inhibition from acetic acid, which is a potent inhibitor for cellulosic ethanol production by microbial fermentations, SET5 and PPR1 were overexpressed in Saccharomyces cerevisiae BY4741. With 5 g/L acetic acid addition, engineered strains BY4741/SET5 and BY4741/PPR1 showed improved growth and enhanced ethanol fermentation performance compared to that with the control strain. Similar results were also observed in ethanol production using corn stover hydrolysate. Further studies indicated that SET5 and PPR1 overexpression in S. cerevisiae significantly improved activities of antioxidant enzymes and ATP generation in the presence of acetic acid, and consequently decreased intracellular accumulation of reactive oxygen species (50.9 and 45.7%, respectively). These results revealed the novel functions of SET5 and PPR1 for the improvement of yeast acetic acid tolerance, and also implicated the involvement of these proteins in oxidative stress defense and energy metabolism in S. cerevisiae. This work also demonstrated that overexpression of SET5 and PPR1 would be a feasible strategy to increase cellulosic ethanol production efficiency.

  20. Improved enzymatic saccharification of steam exploded cotton stalk using alkaline extraction and fermentation of cellulosic sugars into ethanol. (United States)

    Keshav, Praveen K; Naseeruddin, Shaik; Rao, L Venkateswar


    Cotton stalk, a widely available and cheap agricultural residue lacking economic alternatives, was subjected to steam explosion in the range 170-200°C for 5min. Steam explosion at 200°C and 5min led to significant hemicellulose solubilization (71.90±0.10%). Alkaline extraction of steam exploded cotton stalk (SECOH) using 3% NaOH at room temperature for 6h led to 85.07±1.43% lignin removal with complete hemicellulose solubilization. Besides, this combined pretreatment allowed a high recovery of the cellulosic fraction from the biomass. Enzymatic saccharification was studied between steam exploded cotton stalk (SECS) and SECOH using different cellulase loadings. SECOH gave a maximum of 785.30±8.28mg/g reducing sugars with saccharification efficiency of 82.13±0.72%. Subsequently, fermentation of SECOH hydrolysate containing sugars (68.20±1.16g/L) with Saccharomyces cerevisiae produced 23.17±0.84g/L ethanol with 0.44g/g yield.

  1. Kinetic study of batch and fed-batch enzymatic saccharification of pretreated substrate and subsequent fermentation to ethanol

    Directory of Open Access Journals (Sweden)

    Gupta Rishi


    Full Text Available Abstract Background Enzymatic hydrolysis, the rate limiting step in the process development for biofuel, is always hampered by its low sugar concentration. High solid enzymatic saccharification could solve this problem but has several other drawbacks such as low rate of reaction. In the present study we have attempted to enhance the concentration of sugars in enzymatic hydrolysate of delignified Prosopis juliflora, using a fed-batch enzymatic hydrolysis approach. Results The enzymatic hydrolysis was carried out at elevated solid loading up to 20% (w/v and a comparison kinetics of batch and fed-batch enzymatic hydrolysis was carried out using kinetic regimes. Under batch mode, the actual sugar concentration values at 20% initial substrate consistency were found deviated from the predicted values and the maximum sugar concentration obtained was 80.78 g/L. Fed-batch strategy was implemented to enhance the final sugar concentration to 127 g/L. The batch and fed-batch enzymatic hydrolysates were fermented with Saccharomyces cerevisiae and ethanol production of 34.78 g/L and 52.83 g/L, respectively, were achieved. Furthermore, model simulations showed that higher insoluble solids in the feed resulted in both smaller reactor volume and shorter residence time. Conclusion Fed-batch enzymatic hydrolysis is an efficient procedure for enhancing the sugar concentration in the hydrolysate. Restricting the process to suitable kinetic regimes could result in higher conversion rates.

  2. Ethanol cellular defense induce unfolded protein response in yeast

    Directory of Open Access Journals (Sweden)

    Elisabet eNavarro-Tapia


    Full Text Available Ethanol is a valuable industrial product and a common metabolite used by many cell types. However, this molecule produces high levels of cytotoxicity affecting cellular performance at several levels. In the presence of ethanol, cells must adjust some of their components, such as the membrane lipids to maintain homeostasis. In the case of microorganism as Saccharomyces cerevisiae, ethanol is one of the principal products of their metabolism and is the main stress factor during fermentation. Although many efforts have been made, mechanisms of ethanol tolerance are not fully understood and very little evidence is available to date for specific signaling by ethanol in the cell. This work studied two Saccharomyces cerevisiae strains, CECT10094 and Temohaya-MI26, isolated from flor wine and agave fermentation (a traditional fermentation from Mexico respectively, which differ in ethanol tolerance, in order to understand the molecular mechanisms underlying the ethanol stress response and the reasons for different ethanol tolerance. The transcriptome was analyzed after ethanol stress and, among others, an increased activation of genes related with the unfolded protein response (UPR and its transcription factor, Hac1p, was observed in the tolerant strain CECT10094. We observed that this strain also resist more UPR agents than Temohaya-MI26 and the UPR-ethanol stress correlation was corroborated observing growth of 15 more strains and discarding UPR correlation with other stresses as thermal or oxidative stress. Furthermore, higher activation of UPR pathway in the tolerant strain CECT10094 was observed using a UPR mCherry reporter. Finally, we observed UPR activation in response to ethanol stress in other S. cerevisiae ethanol tolerant strains as the wine strains T73 and EC1118. This work demonstrates that the UPR pathway is activated under ethanol stress occurring in a standard fermentation and links this response to an enhanced ethanol tolerance. Thus

  3. Advances in fed-batch ethanol fermentation technologies%乙醇补料发酵技术研究进展

    Institute of Scientific and Technical Information of China (English)

    郭加明; 杨功勋; 胡纯铿; 詹美蓉; 张新华


    As a renewable and clean energy,development and utilization of fuel ethanol has attracted much attention,and consequently there is increasingly in-depth research of the fermentation processes. In recent years,various approaches of fed-batch fermentation have been attempted to investigate their suitability for ethanol production and eventually demonstrated their good potential with the advantages,such as decreased substrate inhibition,and alleviated effects of the toxic compounds released in the dilute-acid pretreatment of lignocellulose. However,due to the existing problems,such as complexity of ethanol fermentation process and lack of in-depth investigations into feeding control strategies,the application of this technology to large-scale production of fuel ethanol has been restricted. This paper reviews major progress of ethanol fed-batch fermentation technologies , particularly focusing on the application of fed-batch approaches to ethanol production using lignocellulose as feedstock and high concentration ethanol fermentation,as well as specific fed-batch control strategies. Finally,more efforts should be made to understand fed-batch ethanol fermentation kinetics and feeding control theory,and to develop new types of sensors and online monitoring technologies.%作为一种可再生的清洁能源,燃料乙醇的开发利用备受关注,对其发酵工艺的研究也日益深入。近年来,补料发酵工艺逐渐应用于燃料乙醇的生产研究中,并以其降低基质抑制和减轻纤维素稀酸水解液中有毒成分的影响等优点而显示了良好的发展潜力,但由于发酵过程的复杂性和对补料控制策略的研究尚不深入等存在的问题,使该技术在燃料乙醇规模化生产中的应用受到制约。本文介绍了国内外乙醇补料发酵研究的主要进展,着重概述补料发酵技术在乙醇两大重要发酵工艺--纤维素乙醇工艺和超高浓度乙醇发酵工艺中的应用以及补料调

  4. Pressurised gasification of wet ethanol fermentation residue for synthesis gas production. (United States)

    Koido, Kenji; Hanaoka, Toshiaki; Sakanishi, Kinya


    Pressurised steam gasification of wet biomass in a fixed-bed downdraft gasifier was implemented to identify reaction conditions yielding the highest synthesis gas concentration and efficiency, and to examine the generation of sulphur compounds. The gasification of lignin-rich fermentation residue derived from a bench-plant for bioethanol production from woody biomass was investigated at p=0.99MPa and T=750-900°C for steam to biomass ratios (S/B) of 3.4-17 and equivalence ratios (φ) of 3.3-∞. The results showed that the highest concentration of around 70mol% was obtained at T⩾850°C, φ=13 and S/B=3.4, the highest efficiency of 0.26 was obtained at T=900°C, φ=3.3 and S/B=3.4, and sulphur compounds were H2S and COS. For the production of BTL synthesis gas, pressurised gasification has the potential to convert the wet residue below 77.3wt.% moisture contents.

  5. Histone modifying proteins Gcn5 and Hda1 affect flocculation in Saccharomyces cerevisiae during high-gravity fermentation. (United States)

    Dietvorst, Judith; Brandt, Anders


    The performance of yeast is often limited by the constantly changing environmental conditions present during high-gravity fermentation. Poor yeast performance contributes to incomplete and slow utilization of the main fermentable sugars which can lead to flavour problems in beer production. The expression of the FLO and MAL genes, which are important for the performance of yeast during industrial fermentations, is affected by complex proteins associated with Set1 (COMPASS) resulting in the induction of flocculation and improved maltose fermentation capacity during the early stages of high-gravity fermentation. In this study, we investigated a possible role for other histone modifying proteins. To this end, we tested a number of histone deacetylases (HDACs) and histone acetyltransferases and we report that flocculation is induced in absence of the histone deacetylase Hda1 or the histone acetyltransferase Gcn5 during high-gravity fermentation. The absence of Gcn5 protein also improved utilization of high concentrations of maltose. Deletion of SIR2 encoding the HDA of the silent informator regulator complex, did not affect flocculation under high-gravity fermentation conditions. Despite the obvious roles for Hda1 and Gcn5 in flocculation, this work indicates that COMPASS mediated silencing is the most important amongst the histone modifying components to control the expression of the FLO genes during high-gravity fermentation.

  6. Biodetoxification of toxins generated from lignocellulose pretreatment using a newly isolated fungus, Amorphotheca resinae ZN1, and the consequent ethanol fermentation

    Directory of Open Access Journals (Sweden)

    Wang Wei


    Full Text Available Abstract Background Degradation of the toxic compounds generated in the harsh pretreatment of lignocellulose is an inevitable step in reducing the toxin level for conducting practical enzymatic hydrolysis and ethanol fermentation processes. Various detoxification methods have been tried and many negative outcomes were found using these methods, such as the massive freshwater usage and wastewater generation, loss of the fine lignocellulose particles and fermentative sugars and incomplete removal of inhibitors. An alternate method, biodetoxification, which degrades the toxins as part of their normal metabolism, was considered a promising option for the removal of toxins without causing the above problems. Results A kerosene fungus strain, Amorphotheca resinae ZN1, was isolated from the microbial community growing on the pretreated corn stover material. The degradation of the toxins as well as the lignocelluloses-derived sugars was characterized in different ways, and the results show that A. resinae ZN1 utilized each of these toxins and sugars as the sole carbon sources efficiently and grew quickly on the toxins. It was found that the solid-state culture of A. resinae ZN1 on various pretreated lignocellulose feedstocks such as corn stover, wheat straw, rice straw, cotton stalk and rape straw degraded all kinds of toxins quickly and efficiently. The consequent simultaneous saccharification and ethanol fermentation was performed at the 30% (wt/wt solid loading of the detoxified lignocellulosic feedstocks without a sterilization step, and the ethanol titer in the fermentation broth reached above 40 g/L using food crop residues as feedstocks. Conclusions The advantages of the present biodetoxification by A. resinae ZN1 over the known detoxification methods include zero energy input, zero wastewater generation, complete toxin degradation, processing on solid pretreated material, no need for sterilization and a wide lignocellulose feedstock spectrum

  7. Hydrogen production with effluent from an ethanol-H2-coproducing fermentation reactor using a single-chamber microbial electrolysis cell. (United States)

    Lu, Lu; Ren, Nanqi; Xing, Defeng; Logan, Bruce E


    Hydrogen can be produced by bacterial fermentation of sugars, but substrate conversion to hydrogen is incomplete. Using a single-chamber microbial electrolysis cell (MEC), we show that additional hydrogen can be produced from the effluent of an ethanol-type dark-fermentation reactor. An overall hydrogen recovery of 83+/-4% was obtained using a buffered effluent (pH 6.7-7.0), with a hydrogen production rate of 1.41+/-0.08 m(3) H(2)/m(3) reactor/d, at an applied voltage of E(ap)=0.6 V. When the MEC was combined with the fermentation system, the overall hydrogen recovery was 96%, with a production rate of 2.11 m(3) H(2)/m(3)/d, corresponding to an electrical energy efficiency of 287%. High cathodic hydrogen recoveries (70+/-5% to 94+/-4%) were obtained at applied voltages of 0.5-0.8 V due to shorter cycle times, and repression of methanogen growth through exposure of the cathode to air after each cycle. Addition of a buffer to the fermentation effluent was critical to MEC performance as there was little hydrogen production using unbuffered effluent (0.0372 m(3) H(2)/m(3)/d at E(ap)=0.6 V, pH 4.5-4.6). These results demonstrate that hydrogen yields from fermentation can be substantially increased by using MECs.

  8. Techno-economic analysis of ethanol production from sugarcane bagasse using a Liquefaction plus Simultaneous Saccharification and co-Fermentation process. (United States)

    Gubicza, Krisztina; Nieves, Ismael U; Sagues, William J; Barta, Zsolt; Shanmugam, K T; Ingram, Lonnie O


    A techno-economic analysis was conducted for a simplified lignocellulosic ethanol production process developed and proven by the University of Florida at laboratory, pilot, and demonstration scales. Data obtained from all three scales of development were used with Aspen Plus to create models for an experimentally-proven base-case and 5 hypothetical scenarios. The model input parameters that differed among the hypothetical scenarios were fermentation time, enzyme loading, enzymatic conversion, solids loading, and overall process yield. The minimum ethanol selling price (MESP) varied between 50.38 and 62.72 US cents/L. The feedstock and the capital cost were the main contributors to the production cost, comprising between 23-28% and 40-49% of the MESP, respectively. A sensitivity analysis showed that overall ethanol yield had the greatest effect on the MESP. These findings suggest that future efforts to increase the economic feasibility of a cellulosic ethanol process should focus on optimization for highest ethanol yield.

  9. Biological conversion of forage sorghum biomass to ethanol by steam explosion pretreatment and simultaneous hydrolysis and fermentation at high solid content

    Energy Technology Data Exchange (ETDEWEB)

    Manzanares, Paloma; Ballesteros, Ignacio; Negro, Maria Jose; Oliva, Jose Miguel; Gonzalez, Alberto; Ballesteros, Mercedes [Renewable Energy Department-CIEMAT, Biofuels Unit, Madrid (Spain)


    In this work, forage sorghum biomass was studied as feedstock for ethanol production by a biological conversion process comprising the steps of hydrothermal steam explosion pretreatment, enzymatic hydrolysis with commercial enzymes, and fermentation with the yeast Saccharomyces cerevisiae. Steam explosion conditions were optimized using a response surface methodology considering temperature (180-230 C) and time (2-10 min). Sugar recovery in the pretreatment and the enzymatic digestibility of the pretreated solid were used to determine the optimum conditions, i.e., 220 C and 7 min. At these conditions, saccharification efficiency attained 89 % of the theoretical and the recovery of xylose in the prehydrolyzate accounted for 35 % of the amount of xylose present in raw material. Then, a simultaneous hydrolysis and fermentation (SSF) process was tested at laboratory scale on the solid fraction of forage sorghum pretreated at optimum condition, in order to evaluate ethanol production. The effect of the enzyme dose and the supplementation with xylanase enzyme of the cellulolytic enzyme cocktail was studied at increasing solid concentration up to 18 % (w/w) in SSF media. Results show good performance of SSF in all consistencies tested with a significant effect of increasing enzyme load in SSF yield and final ethanol concentration. Xylanase supplementation allows increasing solid concentration up to 18 % (w/w) with good SSF performance and final ethanol content of 55 g/l after 4-5 days. Based on this result, about 190 l of ethanol could be obtained from 1 t of untreated forage sorghum, which means a transformation yield of 85 % of the glucose contained in the feedstock. (orig.)

  10. Direct fermentation of gelatinized cassava starch to acetone, butanol, and ethanol using Clostridium acetobutylicum mutant obtained by atmospheric and room temperature plasma. (United States)

    Li, Han-guang; Luo, Wei; Wang, Qiang; Yu, Xiao-bin


    The mutant strain designated as ART18, obtained from the wild-type strain Clostridium acetobutylicum PW12 treated by atmospheric and room temperature plasma, showed higher solvent tolerance and butanol production than that of the wild-type strain. The production of butanol was 11.3 ± 0.5 g/L, 31 % higher than that of the wild-type strain when it was used for acetone, butanol, and ethanol fermentation in P2 medium. Furthermore, the effects of cassava flour concentration, pH regulators, and vitamins on the ABE production were also investigated. The highest butanol production of 15.8 ± 0.8 g/L and butanol yield (0.31 g/g) were achieved after the above factors were optimized. When acetone, butanol, and ethanol fermentation by ART18 was carried out in a 15-L bioreactor, the butanol production, the productivity of butanol, and the total solvent were 16.3 ± 0.9, 0.19, and 0.28 g/L(/)h, respectively. These results indicate that ART18 is a promising industrial producer in ABE fermentation.

  11. An integrative process model of enzymatic biodiesel production through ethanol fermentation of brown rice followed by lipase-catalyzed ethanolysis in a water-containing system. (United States)

    Adachi, Daisuke; Koda, Risa; Hama, Shinji; Yamada, Ryosuke; Nakashima, Kazunori; Ogino, Chiaki; Kondo, Akihiko


    We attempted to integrate lipase-catalyzed ethanolysis into fermentative bioethanol production. To produce bioethanol, ethanol fermentation from brown rice was conducted using a tetraploid Saccharomyces cerevisiae expressing α-amylase and glucoamylase. The resultant ethanol was distilled and separated into three fractions with different concentrations of water and fusel alcohols. In ethanolysis using the first fraction with 89.3% ethanol, a recombinant Aspergillus oryzae whole-cell biocatalyst expressing Fusarium heterosporum lipase (r-FHL) afforded the highest ethyl ester content of 94.0% after 96 h. Owing to a high concentration of water in the bioethanol solutions, r-FHL, which works best in the presence of water when processing ethanolysis, was found to be more suitable for the integrative process than a commercial immobilized Candida antarctica lipase. In addition, r-FHL was used for repeated-batch ethanolysis, resulting in an ethyl ester content of more than 80% even after the fifth batch. Fusel alcohols such as 1-butanol and isobutyl alcohol are thought to decrease the lipase activity of r-FHL. Using this process, a high ethyl ester content was obtained by simply mixing bioethanol, plant oil, and lipase with an appropriate adjustment of water concentration. The developed process model, therefore, would contribute to biodiesel production from only biomass-derived feedstocks.

  12. Separate hydrolysis and fermentation (SHF) of Prosopis juliflora, a woody substrate, for the production of cellulosic ethanol by Saccharomyces cerevisiae and Pichia stipitis-NCIM 3498. (United States)

    Gupta, Rishi; Sharma, Krishna Kant; Kuhad, Ramesh Chander


    Prosopis juliflora (Mesquite) is a raw material for long-term sustainable production of cellulosics ethanol. In this study, we used acid pretreatment, delignification and enzymatic hydrolysis to evaluate the pretreatment to produce more sugar, to be fermented to ethanol. Dilute H(2)SO(4) (3.0%,v/v) treatment resulted in hydrolysis of hemicelluloses from lignocellulosic complex to pentose sugars along with other byproducts such as furfural, hydroxymethyl furfural (HMF), phenolics and acetic acid. The acid pretreated substrate was delignified to the extent of 93.2% by the combined action of sodium sulphite (5.0%,w/v) and sodium chlorite (3.0%,w/v). The remaining cellulosic residue was enzymatically hydrolyzed in 0.05 M citrate phosphate buffer (pH 5.0) using 3.0 U of filter paper cellulase (FPase) and 9.0 U of beta-glucosidase per mL of citrate phosphate buffer. The maximum enzymatic saccharification of cellulosic material (82.8%) was achieved after 28 h incubation at 50 degrees C. The fermentation of both acid and enzymatic hydrolysates, containing 18.24 g/L and 37.47 g/L sugars, with Pichia stipitis and Saccharomyces cerevisiae produced 7.13 g/L and 18.52 g/L of ethanol with corresponding yield of 0.39 g/g and 0.49 g/g, respectively.

  13. Enzymatic digestibility and ethanol fermentability of AFEX-treated starch-rich lignocellulosics such as corn silage and whole corn plant

    Directory of Open Access Journals (Sweden)

    Thelen Kurt D


    Full Text Available Abstract Background Corn grain is an important renewable source for bioethanol production in the USA. Corn ethanol is currently produced by steam liquefaction of starch-rich grains followed by enzymatic saccharification and fermentation. Corn stover (the non-grain parts of the plant is a potential feedstock to produce cellulosic ethanol in second-generation biorefineries. At present, corn grain is harvested by removing the grain from the living plant while leaving the stover behind on the field. Alternatively, whole corn plants can be harvested to cohydrolyze both starch and cellulose after a suitable thermochemical pretreatment to produce fermentable monomeric sugars. In this study, we used physiologically immature corn silage (CS and matured whole corn plants (WCP as feedstocks to produce ethanol using ammonia fiber expansion (AFEX pretreatment followed by enzymatic hydrolysis (at low enzyme loadings and cofermentation (for both glucose and xylose using a cellulase-amylase-based cocktail and a recombinant Saccharomyces cerevisiae 424A (LNH-ST strain, respectively. The effect on hydrolysis yields of AFEX pretreatment conditions and a starch/cellulose-degrading enzyme addition sequence for both substrates was also studied. Results AFEX-pretreated starch-rich substrates (for example, corn grain, soluble starch had a 1.5-3-fold higher enzymatic hydrolysis yield compared with the untreated substrates. Sequential addition of cellulases after hydrolysis of starch within WCP resulted in 15-20% higher hydrolysis yield compared with simultaneous addition of hydrolytic enzymes. AFEX-pretreated CS gave 70% glucan conversion after 72 h of hydrolysis for 6% glucan loading (at 8 mg total enzyme loading per gram glucan. Microbial inoculation of CS before ensilation yielded a 10-15% lower glucose hydrolysis yield for the pretreated substrate, due to loss in starch content. Ethanol fermentation of AFEX-treated (at 6% w/w glucan loading CS hydrolyzate (resulting

  14. Enzymatic digestibility and ethanol fermentability of AFEX-treated starch-rich lignocellulosics such as corn silage and whole corn plant (United States)


    Background Corn grain is an important renewable source for bioethanol production in the USA. Corn ethanol is currently produced by steam liquefaction of starch-rich grains followed by enzymatic saccharification and fermentation. Corn stover (the non-grain parts of the plant) is a potential feedstock to produce cellulosic ethanol in second-generation biorefineries. At present, corn grain is harvested by removing the grain from the living plant while leaving the stover behind on the field. Alternatively, whole corn plants can be harvested to cohydrolyze both starch and cellulose after a suitable thermochemical pretreatment to produce fermentable monomeric sugars. In this study, we used physiologically immature corn silage (CS) and matured whole corn plants (WCP) as feedstocks to produce ethanol using ammonia fiber expansion (AFEX) pretreatment followed by enzymatic hydrolysis (at low enzyme loadings) and cofermentation (for both glucose and xylose) using a cellulase-amylase-based cocktail and a recombinant Saccharomyces cerevisiae 424A (LNH-ST) strain, respectively. The effect on hydrolysis yields of AFEX pretreatment conditions and a starch/cellulose-degrading enzyme addition sequence for both substrates was also studied. Results AFEX-pretreated starch-rich substrates (for example, corn grain, soluble starch) had a 1.5-3-fold higher enzymatic hydrolysis yield compared with the untreated substrates. Sequential addition of cellulases after hydrolysis of starch within WCP resulted in 15-20% higher hydrolysis yield compared with simultaneous addition of hydrolytic enzymes. AFEX-pretreated CS gave 70% glucan conversion after 72 h of hydrolysis for 6% glucan loading (at 8 mg total enzyme loading per gram glucan). Microbial inoculation of CS before ensilation yielded a 10-15% lower glucose hydrolysis yield for the pretreated substrate, due to loss in starch content. Ethanol fermentation of AFEX-treated (at 6% w/w glucan loading) CS hydrolyzate (resulting in 28 g/L ethanol

  15. Application of an Ethanol Compound Enzyme in the Fermentation of Fuel Ethanol%一种酒精复合酶在燃料乙醇发酵中的应用效果

    Institute of Scientific and Technical Information of China (English)

    黄玉涛; 邹婷婷; 吴娟; 黄丽丽; 孙沛勇; 刘钺


    In this study, the residual sugar degradation effects of alcohol compound enzyme KDN401 in three kinds of substrate (cassava flour, corn flour and mixed raw materials:70%wheat flour paste and 30%corn) were investigated. And statistical analysis of the fermentation results was performed by Mood median test. The results showed that, the addition of KDN401 in the fermentation of ethanol by cassava flour had no significant effects in reducing residual sugar and increasing alcohol content (P>0.05), however, the addition of KDN401 in the fermentation of ethanol by corn flour/mixed raw materials had significant effects in reducing residual sugar and increasing alcohol content (P<0.05). There-fore, the selective addition of ethanol compound enzyme could improve fermentation quality, reduce costs, and increase the benefits for the fuel ethanol enterprise.%考察了酒精复合酶KDN401在木薯粉、玉米粉和混合原料(70%小麦面浆加30%玉米)3种底物中的降残糖效果,并运用Mood中位数检验对发酵结果进行统计分析,结果表明,木薯原料乙醇发酵过程中添加酒精复合酶KDN401,对降低残糖、提高酒精度效果不显著(P<0.05),而玉米粉和混合原料乙醇发酵过程中,添加酒精复合酶KDN401,其降糖和提高酒精度均显著(P<0.05)。对于柔性燃料乙醇企业来说,灵活选择添加酒精复合酶,能够提高发酵质量,降低成本,从而提高企业效益。

  16. Effect of Steam Explosion Pretreatment on Bamboo for Enzymatic Hydrolysis and Ethanol Fermentation


    Zhiqiang Li; Benhua Fei; Zehui Jiang


    Based on the steam explosion pretreatment that has been applied to other types of lignocellulosic biomass, the steam explosion pretreatment of bamboo, along with a study of the chemical compositions and enzymatic hydrolyzability of substrates, was conducted. The results show that steam explosion pretreatment can greatly enhance the cellulose-to-glucose conversion yield after enzymatic hydrolysis, which is sometimes affected by bamboo age and steam explosion conditions. When the steam explosio...

  17. Efficient carbon dioxide utilization and simultaneous hydrogen enrichment from off-gas of acetone-butanol-ethanol fermentation by succinic acid producing Escherichia coli. (United States)

    He, Aiyong; Kong, Xiangping; Wang, Chao; Wu, Hao; Jiang, Min; Ma, Jiangfeng; Ouyang, Pingkai


    The off-gas from acetone-butanol-ethanol (ABE) fermentation was firstly used to be CO2 source (co-substrate) for succinic acid production. The optimum ratio of H2/CO2 indicated higher CO2 partial pressures with presence of H2 could enhance C4 pathway flux and reductive product productivity. Moreover, when an inner recycling bioreactor was used for CO2 recycling at a high total pressure (0.2Mpa), a maximum succinic acid concentration of 65.7g·L(-1) was obtained, and a productivity of 0.76g·L(-1)·h(-1) and a high yield of 0.86g·g(-1) glucose were achieved. Furthermore, the hydrogen content was simultaneously enriched to 92.7%. These results showed one successful attempt to reuse the off-gas of ABE fermentation which can be an attractive CO2 source for succinic acid production.

  18. Co-fermentation of hemicellulose and starch from barley straw and grain for efficient pentoses utilization in acetone-butanol-ethanol production. (United States)

    Yang, Ming; Kuittinen, Suvi; Zhang, Junhua; Vepsäläinen, Jouko; Keinänen, Markku; Pappinen, Ari


    This study aims to efficiently use hemicellulose-based biomass for ABE (acetone-butanol-ethanol) production by co-fermentation with starch-based biomass. Two processes were investigated: (I) co-fermentation of sugars derived from hemicellulose and starch in a mixture of barley straw and grain that was pretreated with dilute acid; (II) co-fermentation of straw hemicellulosic hydrolysate and gelatinized grain slurry in which the straw was pretreated with dilute acid. The two processes produced 11.3 and 13.5 g/L ABE that contains 7.4 and 7.8 g/L butanol, respectively. In process I, pretreatment with 1.0% H2SO4 resulted in better ABE fermentability than with 1.5% H2SO4, but only 19% of pentoses were consumed. In process II, 95% of pentoses were utilized even in the hemicellulosic hydrolysate pretreated with more severe condition (1.5% H2SO4). The results suggest that process II is more favorable for hemicellulosic biomass utilization, and it is also attractive for sustainable biofuel production due to great biomass availability.

  19. Effect of aeration on D-xylose fermentation by Pachysolen tannophilus, Pichia stipitis, Kluyveromyces marxianus and Candida shehatae

    Energy Technology Data Exchange (ETDEWEB)

    Delgenes, J.P.; Moletta, R.; Navarro, J.M.


    The fermentation of D-xylose by Pachysolen tannophilus Y2460, Pichia stipitis Y7124, Kluyveromyces marxianus Y2415 and Candida shehatae Y12878 was investigated in aerobic, anaerobic and microaerophilic batch cultures. The aeration rate greatly influenced the fermentations; growth, rate of ethanol production and oxidation of ethanol are affected. Of the strains tested, Pichia stipitis appears superior; under anaerobic conditions it converts D-xylose (20 g/l) to ethanol with a yield of 0.04 g/l and it exhibits the highest ethanol specific productivity (3.5 g of ethanol per g dry cell per day) under microaerophilic conditions. 10 references.

  20. Comparison of SHF and SSF processes from steam-exploded wheat straw for ethanol production by xylose-fermenting and robust glucose-fermenting Saccharomyces cerevisiae strains

    DEFF Research Database (Denmark)

    Tomas Pejo, Elia; Oliva, Jose M.; Ballesteros, Mercedes


    In this study, bioethanol production from steam-exploded wheat straw using different process configurations was evaluated using two Saccharomyces cerevisiae strains, F12 and Red Star. The strain F12 has been engineerically modified to allow xylose consumption as cereal straw contain considerable...... concentration was improved in all tests due to the increase of potential fermentable sugars in the fermentation broth. Inhibitory compounds present in the pretreated wheat straw caused a significantly negative effect on the fermentation rate. However, it was found that the inhibitors furfural and HMF were...

  1. Fermentation of grain sorghum starch by co-cultivation of Schwanniomyces occidentalis and Saccharomyces cerevisiae

    Energy Technology Data Exchange (ETDEWEB)

    Horn, C.H.; Preez, J.C. du; Kilian, S.G. (Orange Free State Univ., Bloemfontein (ZA). Dept. of Microbiology and Biochemistry)


    The amylases of a Schwanniomyces occidentalis mutant hydrolysed grain sorghum starch completely. Heat pretreatment to effect gelatinization was essential for total starch hydrolysis. Ethanol fermentations were conducted by using a stationary-phase culture of S. occidentalis in conjunction with Saccharomyces cerevisiae to ferment the sugars liberated from the grain sorghum starch by the amylases of S. occidentalis. Increasing the grain sorghum concentration from 8 to 28% (m/v) did not affect the final ethanol yield of 0.45 g ethanol/g glucose equivalents, although the fermentation rate decreased considerably at the higher slurry concentration, requiring 8 days for completion of the fermentation. A 28% grain sorghum slurry yielded 12.5% (w/v) ethanol, indicating that nearly 390 1 of ethanol could be produced per tonne grain sorghum, with about 430 kg residual biomass containing 43% crude protein. (Author).

  2. 玉米秸秆水抽提物对乙醇发酵的影响%Effect of water extractives from corn stover on ethanol fermentation

    Institute of Scientific and Technical Information of China (English)

    荣亚运; 朱圆圆; 朱均均; 陈旭; 徐勇; 勇强; 余世袁


    Water extractives were obtained by water extraction of corn stover .The effects of water extractives or its diluted acid hydro-lyzate from corn stover on xylose fermentation to ethanol by Pichia stipitis and glucose fermentation to ethanol by Saccharomyces cerevisi-ae were investigated .The results showed that , compared to the control , there were some negative effect on xylose fermentation to etha-nol by P.stipitis when the water extractives were added to the medium .The degree of inhibition increased with the increase of water ex-tractives, but not obvious.The sugar utilization ratio increased when the fermentation time increased to 48 h, however, the ethanol yield decreased ( less than 80%) .There was little negative effect on glucose fermentation to ethanol by S.cerevisiae when the water ex-tractives were added to the medium .When the diluted acid hydrolyzate of water extractives was added to the medium , the fermentation time of xylose to ethanol by P.stipitis extended from 24 h to 48 h, and the ethanol yield decreased while the sugar utilization ratio was the same.However, the diluted acid hydrolyzate of water extractives still had little negative effect on glucose fermentation to ethanol by S.cerevisiae.Therefore, P.stipitis was more sensitive than S.cerevisiae to the inhibitors existed in the water extractives and its diluted acid hydrolyzate .Water extraction before corn stover pretreatment could reduce the inhibitors produce ; thereby improved the ethanol fermentability by yeasts .Finally, it provides reference for real commercial production of fuel ethanol .%采用水抽提法提取玉米秸秆中的水抽提物,研究水抽提液、水抽提液稀酸水解液对树干毕赤酵母木糖乙醇发酵和酿酒酵母葡萄糖乙醇发酵性能的影响。结果表明,与空白对照相比,添加水抽提液对树干毕赤酵母木糖乙醇发酵性能有一定的抑制作用,随着水抽提液添加体积的增加,抑制程度有所增加,但

  3. Fumonisins in Conventional and Transgenic, Insect-Resistant Maize Intended for Fuel Ethanol Production: Implications for Fermentation Efficiency and DDGS Co-Product Quality

    Directory of Open Access Journals (Sweden)

    Erin L. Bowers


    Full Text Available Mycotoxins in maize grain intended for ethanol production are enriched in co-product dried distiller’s grains and solubles (DDGS and may be detrimental to yeast in fermentation. This study was conducted to examine the magnitude of fumonisin enrichment in DDGS and to analyze the impacts of insect injury, Fusarium ear rot severity, and fumonisin contamination on final ethanol yield. Samples of naturally-contaminated grain (0 to 35 mg/kg fumonisins from field trials conducted in 2008–2011 were fermented and DDGS collected and analyzed for fumonisin content. Ethanol yield (determined gravimetrically was unaffected by fumonisins in the range occurring in this study, and was not correlated with insect injury or Fusarium ear rot severity. Ethanol production was unaffected in fumonisin B1-spiked grain with concentrations from 0 to 37 mg/kg. Bacillus thuringiensis (Bt maize often has reduced fumonisins due to its protection from insect injury and subsequent fungal infection. DDGS derived from Bt and non-Bt maize averaged 2.04 mg/kg and 8.25 mg/kg fumonisins, respectively. Fumonisins were enriched by 3.0× for 50 out of 57 hybrid × insect infestation treatment combinations; those seven that differed were <3.0 (1.56 to 2.56×. This study supports the industry assumption of three-fold fumonisin enrichment in DDGS, with measurements traceable to individual samples. Under significant insect pest pressures, DDGS derived from Bt maize hybrids were consistently lower in fumonisins than DDGS derived from non-Bt hybrids.

  4. High-loading-substrate enzymatic hydrolysis of palm plantation waste followed by unsterilized-mixed-culture fermentation for bio-ethanol production (United States)

    Bardant, Teuku Beuna; Winarni, Ina; Sukmana, Hadid


    It was desired to obtain a general formula for producing bio-ethanol from any part of lignocelluloses wastes that came from palm oil industries due to its abundance. Optimum condition that obtained by using RSM for conducting high-loading-substrate enzymatic hydrolysis of palm oil empty fruit bunch was applied to palm oil trunks and then followed by unsterilized fermentation for producing bio-ethanol. From several optimized conditions investigated, the resulted ethanol concentration could reach 7.92 %v by using 36.5 %w of palm oil trunks but the results were averagely 2.46 %v lower than palm oil empty fruit bunch. The results was statistically compared and showed best correlative coefficient at 0.808 (in scale 0-1) which support the conclusion that the optimum condition for empty fruit bunch and trunks are similar. Utilization of mixed-culture yeast was investigated to produce ethanol from unsterilized hydrolysis product but the improvement wasn't significant compares to single culture yeast.

  5. Bacterial fermentation affects net mineral flux in the large intestine of pigs fed diets with viscous and fermentable nonstarch polysaccharides. (United States)

    Metzler-Zebeli, B U; Hooda, S; Mosenthin, R; Gänzle, M G; Zijlstra, R T


    The impact of colonic fermentation on postileal absorption of Ca, Mg, P, Cu, Fe, Mn, and Zn was investigated in 8 ileally cannulated grower pigs (initial BW = 29.1 ± 1.6 kg) according to a double 4 × 4 Latin square. A semi-purified diet was supplemented with 5.20% low viscous, low fermentable cellulose (CEL), 6.25% high viscous, low fermentable carboxymethylcellulose (CMC), 8.95% low viscous, high fermentable oat beta-glucan (LG), or 9.25% high viscous, high fermentable oat beta-glucan (HG), resulting in 5% actual added nonstarch polysaccharides (NSP) in the diets. Because of the intrinsic mineral content in LG and HG, pigs receiving the LG and HG diets had a greater (P minerals reached the large intestine for the 4 diets as indicated by the 60 to 86% less (P mineral retention was generally less (P mineral flux in the large intestine that, in turn, can influence mineral excretion in feces. Additionally, negative effects of CEL on apparent retention may increase the daily requirement for minerals of grower pigs.

  6. Charge and geometry of residues in the loop 2 β hairpin differentially affect agonist and ethanol sensitivity in glycine receptors. (United States)

    Perkins, Daya I; Trudell, James R; Asatryan, Liana; Davies, Daryl L; Alkana, Ronald L


    Recent studies highlighted the importance of loop 2 of α1 glycine receptors (GlyRs) in the propagation of ligand-binding energy to the channel gate. Mutations that changed polarity at position 52 in the β hairpin of loop 2 significantly affected sensitivity to ethanol. The present study extends the investigation to charged residues. We found that substituting alanine with the negative glutamate at position 52 (A52E) significantly left-shifted the glycine concentration response curve and increased sensitivity to ethanol, whereas the negative aspartate substitution (A52D) significantly right-shifted the glycine EC₅₀ but did not affect ethanol sensitivity. It is noteworthy that the uncharged glutamine at position 52 (A52Q) caused only a small right shift of the glycine EC₅₀ while increasing ethanol sensitivity as much as A52E. In contrast, the shorter uncharged asparagine (A52N) caused the greatest right shift of glycine EC₅₀ and reduced ethanol sensitivity to half of wild type. Collectively, these findings suggest that charge interactions determined by the specific geometry of the amino acid at position 52 (e.g., the 1-Å chain length difference between aspartate and glutamate) play differential roles in receptor sensitivity to agonist and ethanol. We interpret these results in terms of a new homology model of GlyR based on a prokaryotic ion channel and propose that these mutations form salt bridges to residues across the β hairpin (A52E-R59 and A52N-D57). We hypothesize that these electrostatic interactions distort loop 2, thereby changing agonist activation and ethanol modulation. This knowledge will help to define the key physical-chemical parameters that cause the actions of ethanol in GlyRs.

  7. High gravity ethanol fermentation from sugarcane juice%高浓度甘蔗汁酒精发酵过程的研究

    Institute of Scientific and Technical Information of China (English)

    郭青松; 伍时华; 赵东玲; 易弋; 黄翠姬


    研究高浓度甘蔗汁酒精发酵过程中糖的消耗,酒精生成以及酵母细胞生长的变化.采用液相色谱法测定各种糖的含量、气相色谱法测定酒精的生成量.试验结果表明,发酵12h时葡萄糖消耗速率最大(9.46(g/L)/h),14h时果糖、蔗糖、总糖消耗速率最大,分别为12.61(g/L)/h,12.30 (g/L)/h,20.59 (g/L)/h;发酵16h时酒精生成速率(7.89(g/L)/h)最大,细胞死亡率(22.9%)开始大于出芽率(12.6%),随后细胞活力逐渐下降.试验最终发酵酒精度12.8%vol,残糖22.50g/L,糖利用率90.9%,发酵效率79.69%.%The changes of sugars (glucose, fructose and sucrose), biomass and ethanol production during the high gravity ethanol fermentation from sugarcane juice by Saccharomyces cerevisiae strain GJ2008 at 32℃ under batch condition in 5L bioreactor were studied. The contents of sugars were detected by HPLC-ELSD, while the ethanol production was determined by gas chromatography (GC). The results showed that the highest glucose consumption rate was 9.46g/(L·h) at 12h, while the highest consumption rates of fructose, sucrose and total sugar were 12.61g/(L·h), 12.30g/(L·h) and 20,59g/(L·h), respectively at 14h. At 16h, the highest ethanol production rate was observed as 7.89g/ (L·h), and the cell death rate (22.9%) became greater than cell budding rate (12.6%). And then, the yeast cell vitality gradually decreased. At the end of fermentation, ethanol content, residual sugar, sugar utilization percentage and fermentation efficiency were 12.8%vol, 22.50g/L, 90.9% and 79.69%, respectively.

  8. Emission of Methane From Enteric Fermentation: National Contribution and Factors Affecting it in Livestock

    Directory of Open Access Journals (Sweden)

    Budi Haryanto


    Full Text Available Changing in atmosphere condition is affected by the quantity of gases produced from all activities on the earth. Gases that have effects on global warming are CO2, N2O, H2O, and CH4 (methane. Among other sources of methane are enteric fermentation of organic material from ruminants and feces decomposition. Methane production from ruminants is affected by several factors such as breed/type of animal, feed quality, environmental temperature and physiological status of the animal. Energy as methane in ruminants may reach 2 to 15% of the total energy consumption. To reduce the emission of methane from ruminants, it is necessary to apply a strategic feeding system for more efficient utilization of feed.

  9. 耐热马克斯克鲁维酵母发酵产乙醇研究%Ethanol fermentation by thermotolerant yeast K.marxianus

    Institute of Scientific and Technical Information of China (English)

    戴振鹏; 王永红; 储炬; 庄英萍; 张嗣良


    Using the thermotolerant Kluyveromyces marxianus strain with semi-defined medium, the optimum ethanol fermentation temperature range was 34 ℃ ~ 40 ℃, at which the glucose conversion and ethanol productivity were over 86% and 4.4 g/(L · h) , respectively. When temperature was below 34 ℃, the fermentation period became 2-3 hours longer than that at 34 ℃ ~ 40 ℃, and the glucose conversion and ethanol productivity were 81.4% and 4.15g/(L·h), respectively. While at 45 ℃. K. Marxianus produced 30.52 g/L ethanol, 74. 8% glucose conversion and 2. 95 g/( L · h) ethanol productivity were obtained. Using steam-exploded corn stover enzymatic hydrolysate ( containing 75. 8 g/L glucose) as substrate at 30 ℃ , 37 ℃ , 45 ℃ , all the glucose conversions of 69. 1% 71. 9% , 59. 3% and the ethanol productivity of 0. 56 g/( L · h) , 0. 58 g/( L · h) , 0. 37 g/( L · h) were obviously lower than those with the semi-defined medium. When yeast extract and inorganic salts were added into the enzymatic hydrolysate, the ethanol production increased. Both at 30 ℃ and 37 ℃ glucose conversions were about 10% higher than that without adding yeast extract and inorganic salts, but the ethanol productivities did not increase at all. The results indicated that K. Marxianus had advantages over Saccharomyces cerevisiae in ethanol fermentation at above 37℃ by using steam-exploded corn stover as substrate.%在采用半合成培养基的条件下,耐热的马克斯克鲁维酵母(Kluyveromyces marxianus)的最佳乙醇发酵温度范围是34℃~ 40℃,糖醇转化率超过86%,产率到达4.4 g/(L·h);温度低于34℃,发酵周期要比34℃~40℃长2~3h,其糖醇转化率为81.4%,产率为4.15 g/L·h;在45℃时能发酵产生30.5 g/L乙醇,转化率达到74.8%,产率为2.95 g/(L·).在汽爆玉米秸秆酶解液(含75.8 g/L的葡萄糖)中用K.marxianus进行的发酵实验表明,在30℃、37℃和45℃时,糖醇转化率比在半合成培

  10. Ethanol affects network activity in cultured rat hippocampus: mediation by potassium channels.

    Directory of Open Access Journals (Sweden)

    Eduard Korkotian

    Full Text Available The effects of ethanol on neuronal network activity were studied in dissociated cultures of rat hippocampus. Exposure to low (0.25-0.5% ethanol concentrations caused an increase in synchronized network spikes, and a decrease in the duration of individual spikes. Ethanol also caused an increase in rate of miniature spontaneous excitatory postsynaptic currents. Higher concentrations of ethanol eliminated network spikes. These effects were reversible upon wash. The effects of the high, but not the low ethanol were blocked by the GABA antagonist bicuculline. The enhancing action of low ethanol was blocked by apamin, an SK potassium channel antagonist, and mimicked by 1-EBIO, an SK channel opener. It is proposed that in cultured hippocampal networks low concentration of ethanol is associated with SK channel activity, rather than the GABAergic receptor.

  11. The Research of Newly Immobilized Yeast' s Fermentation of Ethanol%新型固定化酵母细胞发酵生产乙醇的研究

    Institute of Scientific and Technical Information of China (English)

    董江清; 林晓珊; 林旭广; 周天行


    [目的]说明利用甘蔗块作为酵母固定化材料进行固定化酵母发酵相对于游离酵母发酵来说具有优越性,同时探究利用甘蔗汁和废糖蜜作为发酵培养基分别进行发酵时的发酵效果.[方法]共设计12个发酵组,研究发酵培养基和是否进行固定对发酵效果的影响.[结果]以甘蔗汁为发酵培养基时固定化酵母发酵液中乙醇平均体积分数比游离酵母发酵高0.7%,以废糖蜜为发酵培养基时固定化酵母发酵液中乙醇平均体积分数比游离酵母发酵高0.76%.甘蔗汁培养基与废糖蜜培养基对总体发酵效果的影响非常接近.[结论]综合考虑甘蔗汁与废糖蜜的成本,废糖蜜是工业发酵生产乙醇用培养基的更优选择.%[Objective]The experiment was designed to prove that using sugarcane clump as the immobilizing material to ferment was better than dissociative yeasts' fermentation ,and at the same time to explore the fermentation effect of sugarcane and blackstrap when they were used as the fermentation culture [ Method] 12 fermentation groups were arrange to study the influence of the fermentation culture and immobilizing or not to fermentation effect . [ Result ]The fermentation result showed that when blackstrap was used as the fermentation culture ,the average volume fraction of ethanol of the immobilized yeast in the fermentation liquor was 0. 76% more than dissociative yeasts' fermentation;and when sugarcane juice was used as the fermentation culture ,the average volume fraction of ethanol of the immobilized yeast in the fermentation liquor was 0.7% more than dissociative yeasts' fermentation. On the other hand ,the influence of sugarcane juice and blackstrap to fermentation was almost the same. [ Conclusion] Considering the cost of sugarcane juice and blackstrap integrally, blackstrap was the better choice in industrial production of ethanol.

  12. Tea saponins affect in vitro fermentation and methanogenesis in faunated and defaunated rumen fluid

    Institute of Scientific and Technical Information of China (English)

    HU Wei-lian; WU Yue-ming; LIU Jian-xin; GUO Yan-qiu; YE Jun-an


    The effect of tea saponins (TS) on rumen fermentation and methane emission was examined using an in vitro gas production technique named Reading Pressure Technique. Three levels of TS addition (0, 0.2, 0.4 mg/ml) were evaluated in the faunated and defaunated rumen fluid. Compared to the control, TS addition decreased the 24 h gas production in the faunated rumen fluid, but had a minor effect on gas yield in the defaunated rumen fluid. The TS significantly reduced methane production in vitro. In the faunated rumen fluid, 0.2 or 0.4 mg/ml TS decreased the 24 h methane emission by 12.7% or 14.0%, respectively.Rumen fluid pH value was affected neither by TS addition nor by defaunation. The TS addition had only minor effects on volatile fatty acids, but the yield and pattern of volatile fatty acids were greatly affected by defaunation. While the molar proportion of acetate was not affected by defaunation, the propionate was significantly increased and the butyrate significantly decreased.Ammonia-N concentration and microbial protein yield were influenced by TS inclusion and defaunation. Inclusion of 0.4 mg/ml TS increased the microbial protein mass by 18.4% and 13.8% and decreased the ammonia-N concentration by 8.3% and 19.6% in the faunated and defaunated rumen fluid, respectively. Protozoa counts were significantly reduced by TS inclusion. The current study demonstrated the beneficial effect of TS on methane production and rumen fermentation, and indicated that this may be due to the effect of the associated depression on protozoa counts.

  13. Avermectins differentially affect ethanol intake and receptor function: implications for developing new therapeutics for alcohol use disorders. (United States)

    Asatryan, Liana; Yardley, Megan M; Khoja, Sheraz; Trudell, James R; Hyunh, Nhat; Louie, Stan G; Petasis, Nicos A; Alkana, Ronald L; Davies, Daryl L


    Our laboratory is investigating ivermectin (IVM) and other members of the avermectin family as new pharmaco-therapeutics to prevent and/or treat alcohol use disorders (AUDs). Earlier work found that IVM significantly reduced ethanol intake in mice and that this effect likely reflects IVM's ability to modulate ligand-gated ion channels. We hypothesized that structural modifications that enhance IVM's effects on key receptors and/or increase its brain concentration should improve its anti-alcohol efficacy. We tested this hypothesis by comparing the abilities of IVM and two other avermectins, abamectin (ABM) and selamectin (SEL), to reduce ethanol intake in mice, to alter modulation of GABAARs and P2X4Rs expressed in Xenopus oocytes and to increase their ability to penetrate the brain. IVM and ABM significantly reduced ethanol intake and antagonized the inhibitory effects of ethanol on P2X4R function. In contrast, SEL did not affect either measure, despite achieving higher brain concentrations than IVM and ABM. All three potentiated GABAAR function. These findings suggest that chemical structure and effects on receptor function play key roles in the ability of avermectins to reduce ethanol intake and that these factors are more important than brain penetration alone. The direct relationship between the effect of these avermectins on P2X4R function and ethanol intake suggest that the ability to antagonize ethanol-mediated inhibition of P2X4R function may be a good predictor of the potential of an avermectin to reduce ethanol intake and support the use of avermectins as a platform for developing novel drugs to prevent and/or treat AUDs.

  14. Study on fuel ethanol by synchronous saccharification and fermentation from straws%农作物秸秆同步糖化发酵制燃料乙醇条件研究

    Institute of Scientific and Technical Information of China (English)

    王许涛; 谢慧; 耿涛; 王风芹; 任天宝; 宋安东


    用农作物秸秆做原料进行同步糖化发酵制取燃料乙醇,同步糖化发酵的温度不协调以及单批次同步糖化发酵原料用量影响乙醇产量等问题始终制约着工艺的应用.文中进行了主要农作物玉米秸秆和稻草秸秆的3种预处理方式同步糖化发酵和同步糖化发酵工艺过程的补料试验研究.试验结果显示,稀酸预处理稻草粉在液固比为8:1时,同步糖化发酵效果最好,乙醇含量为11.16 g/L,残糖浓度最低为12.07 g/L;补料方式H下乙醇浓度达到最大值10.09 g/L,此补料方式下添加吐温-80、混合菌种时的乙醇产率变化不明显.%Using biomass straws for fuel ethanol synchronous saccharification and fermentation (SSF).Both the coordination of saccharification and fermentation temperature and the initial amount of raw materials for single-batch SSF will affect the ethanol yield.In this paper,the pretreated straws in three methods were used as feedstock for SSF.The test results showed that the straw powder pretreatment with dilute acid in liquid-solid ratio 8:1 was the best,the ethanol content was 11.16 g/L and the lowest residual sugar concentration was 12.07 g/L.With feeding method H the maximum ethanol concentration was 10.09 g/L,when adding Tween-80 and mixed bacteria under this feeding method,therewas no obviously change.

  15. Comparative Study on Conversion Process of Furfural Residue for Ethanol Production by Simultaneous Saccharification and Fermentation%糠醛渣直接同步糖化发酵生产乙醇过程比较研究

    Institute of Scientific and Technical Information of China (English)

    吉骊; 王永淼; 唐勇; 刘志平; 蒋建新


    以糠醛渣为原料,直接同步糖化发酵( SSF)生产乙醇,并与水洗糠醛渣生产乙醇进行对比。通过考察不同条件来优化同步糖化发酵生产工艺条件,并分析表征了SSF过程中乙醇浓度和副产物浓度变化。优化条件为:糠醛渣底物质量分数10%,纤维素酶用量12%,无患子皂素质量浓度0.5 g/L,酵母接种量7 g/L,同步糖化发酵乙醇得率达到其理论得率的93.1%。与水洗糠醛渣相比,糠醛渣直接SSF过程可将原料吸附的5.50%葡萄糖部分转化为乙醇。水洗糠醛渣SSF生产乙醇所产生的副产物要远低于糠醛渣直接生产所产生的副产物,添加无患子皂素可有效抑制糠醛渣同步糖化发酵过程中副产物的产生。%Furfural residues and washed furfural residues were fermented to produce ethanol by simultaneous saccharification and fermentation ( SSF) . The combination factors ( substrate mass fraction, dosage of cellulase, yeast and Sapindus saponin) which affected the concentrations of ethanol and byproduct were optimized by the experiment. The yield of ethanol could reach 93. 1%of the theoretical yield during SSF under the conditions of 10% substrate concentration of unwashed furfural residue, 12%cellulase, 0. 5 g/L Sapindus saponin and 7 g/L inoculum solution. The glucose of furfural residues ( 5. 5%) were partly converted to ethanol compared with washed furfural residues. The byproducts ( lactic acid, glycerol and acetic acid ) concentrations of washed furfural residue in SSF were lower than those of unwashed furfural residue. And the addition of Sapindus saponin could inhibit the produce of byproducts.

  16. Elimination of acetate production to improve ethanol yield during continuous synthesis gas fermentation by engineered biocatalyst Clostridium sp. MTEtOH550. (United States)

    Berzin, Vel; Kiriukhin, Michael; Tyurin, Michael


    Acetogen strain Clostridum sp. MT653 produced acetate 273 mM (p Clostridum sp. MT653 was metabolically engineered to the biocatalyst strain Clostridium sp. MTEtOH550. The biocatalyst increased ethanol yield to 590 mM with no acetate production during single-stage continuous syngas fermentation due to expression of synthetic adh cloned in a multi-copy number expression vector. The acetate production was eliminated by inactivation of the pta gene in Clostridium sp. MTEtOH550. Gene introduction and gene elimination were achieved only using Syngas Biofuels Energy, Inc. electroporation generator. The electrotransformation efficiencies were 8.0 ± 0.2 × 10(6) per microgram of transforming DNA of the expression vector at cell viability ~15%. The frequency of suicidal vector integration to inactivate pta was ~10(-5) per the number of recipient cells. This is the first report on elimination of acetate production and overexpression of synthetic adh gene to engineer acetogen biocatalyst for selective biofuel ethanol production during continuous syngas fermentation.

  17. Enhanced sugar production from pretreated barley straw by additive xylanase and surfactants in enzymatic hydrolysis for acetone-butanol-ethanol fermentation. (United States)

    Yang, Ming; Zhang, Junhua; Kuittinen, Suvi; Vepsäläinen, Jouko; Soininen, Pasi; Keinänen, Markku; Pappinen, Ari


    This study aims to improve enzymatic sugar production from dilute sulfuric acid-pretreated barley straw for acetone-butanol-ethanol (ABE) fermentation. The effects of additive xylanase and surfactants (polyethylene glycol [PEG] and Tween) in an enzymatic reaction system on straw hydrolysis yields were investigated. By combined application of 2g/100g dry-matter (DM) xylanase and PEG 4000, the glucose yield was increased from 53.2% to 86.9% and the xylose yield was increased from 36.2% to 70.2%, which were considerably higher than results obtained with xylanase or surfactant alone. The ABE fermentation of enzymatic hydrolysate produced 10.8 g/L ABE, in which 7.9 g/L was butanol. The enhanced sugar production increased the ABE yield from 93.8 to 135.0 g/kg pretreated straw. The combined application of xylanase and surfactants has a large potential to improve sugar production from barley straw pretreated with a mild acid and that the hydrolysate showed good fermentability in ABE production.

  18. Production of butanol by Clostridium saccharoperbutylacetonicum N1-4 from palm kernel cake in acetone-butanol-ethanol fermentation using an empirical model. (United States)

    Shukor, Hafiza; Al-Shorgani, Najeeb Kaid Nasser; Abdeshahian, Peyman; Hamid, Aidil Abdul; Anuar, Nurina; Rahman, Norliza Abd; Kalil, Mohd Sahaid


    Palm kernel cake (PKC) was used for biobutanol production by Clostridium saccharoperbutylacetonicum N1-4 in acetone-butanol-ethanol (ABE) fermentation. PKC was subjected to acid hydrolysis pretreatment and hydrolysates released were detoxified by XAD-4 resin. The effect of pH, temperature and inoculum size on butanol production was evaluated using an empirical model. Twenty ABE fermentations were run according to an experimental design. Experimental results revealed that XAD-4 resin removed 50% furfural and 77.42% hydroxymethyl furfural. The analysis of the empirical model showed that linear effect of inoculums size with quadratic effect of pH and inoculum size influenced butanol production at 99% probability level (Pproduction were pH 6.28, temperature of 28°C and inoculum size of 15.9%. ABE fermentation was carried out under optimum conditions which 0.1g/L butanol was obtained. Butanol production was enhanced by diluting PKC hydrolysate up to 70% in which 3.59g/L butanol was produced.

  19. Antioxidant properties of certain cereals as affected by food-grade bacteria fermentation. (United States)

    Wang, Chung-Yi; Wu, Sz-Jie; Shyu, Yuan-Tay


    The effects of fermentation by 2 food-grade bacteria (Bacillus subtilis and Lactobacillus plantarum) on antioxidant activities and the contents of phenolics and flavonoids in 4 cereals (specifically adlay, chestnut, lotus seed, and walnut) were determined and compared with those of their non-fermented counterparts. Results showed that antioxidant properties observed in the fermented and non-fermented cereals may vary with fermented starters. Fermentation was observed to increase the phenolic and flavonoid contents of the extracts. The effects on Bacillus-fermented cereals were stronger than on Lactobacillus-fermented cereals. In IC50 values (mg/mL) of extracts, the extracts of fermented cereal showed a stronger DPPH radical scavenging and ferric-reducing activities. Fermentation did not significantly alter the Fe(2+)-chelating activity in the extracts of chestnuts and lotus seeds. All cereals were shown significantly inhibited the production of LPS-induced intracellular reactive oxygen species (ROS) without creating obvious cytotoxic effects in the macrophage cells. These results suggest that the fermentation process enables cereal-based foods with enhanced antioxidant capacities to contribute to health and nutritional improvements in consumers.

  20. Identification and Quantification of Processes Affecting the Fate of Ethanol-Blended Fuel in the Subsurface (United States)

    Devries, J. M.; Mayer, K. U.


    At present, the oil and gas industry distributes gasoline with an ethanol content of up to 10% (E10) to the consumer. However, ethanol advocates are promoting gasoline blends with higher ethanol content to be introduced into the market (e.g., E20, corresponding to an ethanol content of 20%). The likelihood of unintended fuel releases with elevated ethanol concentrations through surficial spills or from underground storage systems will therefore increase. A particular concern is the increased rate of CH4 and CO2 production as the spill biodegrades, which is believed to be associated with the increased ethanol content in the fuel. Consequently, high gas generation rates associated with ethanol-blended fuels may amplify the risk of vapor intrusion of CH4 and BTEX into basements or other subsurface structures that may be nearby. A comprehensive and comparative study on the fate of higher concentration ethanol-blended fuels in the subsurface has not been conducted to date. The present study focuses on determining the fate of ethanol blended fuels in the subsurface through a series of controlled and instrumented laboratory column experiments. The experiments compare the behavior of pure gasoline with that of ethanol-blended fuels for different soil types (sand and silt) in columns 2 meters tall and 30cm in diameter. The column experiments focus on the quantification of gas generation by volatilization and biodegradation and 1-D vertical fate and transport of CO2, CH4, benzene and toluene through the vadose zone. The fuel blends have been injected into the lower third of the columns and gas composition and fluxes within the column are being monitored over time. The goal of this study is to contribute to the scientific foundation that will allow gauging the level of risk and the need for remediation at fuel spill sites with higher ethanol blends.

  1. Ethanol-induced yeast flocculation directed by the promoter of TPS1 encoding trehalose-6-phosphate synthase 1 for efficient ethanol production. (United States)

    Li, Qian; Zhao, Xin-Qing; Chang, Alan K; Zhang, Qiu-Mei; Bai, Feng-Wu


    Yeast flocculation is an important trait in the brewing industry as well as in ethanol production, through which biomass can be recovered by cost-effective sedimentation. However, mass transfer limitation may affect yeast growth and ethanol fermentation if the flocculation occurs earlier before fermentation is completed. In this article, a novel type of cell-cell flocculation induced by trehalose-6-phosphate synthase 1 (TPS1) promoter was presented. The linear cassette HO-P(TPS1)-FLO1(SPSC01)-KanMX4-HO was constructed to transform the non-flocculating industrial yeast S. cerevisiae 4126 by chromosome integration to obtain a new flocculating yeast strain, ZLH01, whose flocculation was induced by ethanol produced during fermentation. The experimental results illustrated that flocculation of ZLH01 was triggered by 3% (v/v) ethanol and enhanced as ethanol concentration increased till complete flocculation was achieved at ethanol concentration of 8% (v/v). Real time PCR analysis confirmed that the expression of FLO1(SPSC01) was dependent on ethanol concentration. The growth and ethanol fermentation of ZLH01 were improved significantly, compared with the constitutive flocculating yeast BHL01 engineered with the same FLO gene but directed by the constitutive 3-phosphoglycerate kinase promoter PGK1, particularly under high temperature conditions. These characteristics make the engineered yeast more suitable for ethanol production from industrial substrates under high gravity and temperature conditions. In addition, this strategy offers advantage in inducing differential expression of other genes for metabolic engineering applications of S. cerevisiae.

  2. Maize stover and cob cell wall composition and ethanol potential as affected by nitrogen fertilization (United States)

    Maize (Zea mays L.) stover and cobs are potential feedstock sources for cellulosic ethanol production. Nitrogen (N) fertilization is an important management decision that influences cellulosic biomass and grain production, but its effect on cell wall composition and subsequent cellulosic ethanol pro...

  3. Integrated distillation-membrane process for bio-ethanol and bio-butanol recovery from actual fermentation broths: Separation energy efficiency and fate of secondary fermentation products (United States)

    A hybrid process integrating vapor stripping with vapor compression and vapor permeation membrane separation, termed Membrane Assisted Vapor Stripping (MAVS), was evaluated for recovery and dehydration of ethanol and/or 1-butanol from aqueous solution as an alternative to convent...

  4. Effect of primary degradation-reaction products from Ammonia Fiber Expansion (AFEX)-treated corn stover on the growth and fermentation of Escherichia coli KO11. (United States)

    Lau, Ming W; Dale, Bruce E


    The primary degradation-reaction products (DRP) identified in Ammonia Fiber Expansion (AFEX)-pretreated corn stover are acetate, lactate, 4-hydroxybenzaldehyde (4HBD) and acetamide. The effects of these products at a broad concentration range were tested on Escherichia coli KO11, a strain engineered for cellulosic ethanol production. Fermentations using glucose or xylose as the sole carbohydrate source and a sugar mixture of glucose and xylose were conducted to determine how these products and sugar selection affected fermentation performance. Co-fermentation of the sugar mixture exhibited the lowest overall ethanol productivity compared to single-sugar fermentations and was more susceptible to inhibition. Metabolic ethanol yield increased with the increasing initial concentration of acetate. Although these degradation-reaction products (with exception of acetamide) are generally perceived to be inhibitory, organic acids and 4-hydroxybenzaldehyde at low levels stimulated fermentation. Adaptation of cells to these products prior to fermentation increased overall fermentation rate.

  5. Ethanol affects striatal interneurons directly and projection neurons through a reduction in cholinergic tone. (United States)

    Blomeley, Craig P; Cains, Sarah; Smith, Richard; Bracci, Enrico


    The acute effects of ethanol on the neurons of the striatum, a basal ganglia nucleus crucially involved in motor control and action selection, were investigated using whole-cell recordings. An intoxicating concentration of ethanol (50 mM) produced inhibitory effects on striatal large aspiny cholinergic interneurons (LAIs) and low-threshold spike interneurons (LTSIs). These effects persisted in the presence of tetrodotoxin and were because of an increase in potassium currents, including those responsible for medium and slow afterhyperpolarizations. In contrast, fast-spiking interneurons (FSIs) were directly excited by ethanol, which depolarized these neurons through the suppression of potassium currents. Medium spiny neurons (MSNs) became hyperpolarized in the presence of ethanol, but this effect did not persist in the presence of tetrodotoxin and was mimicked and occluded by application of the M1 muscarinic receptor antagonist telenzepine. Ethanol effects on MSNs were also abolished by 100 μM barium. This showed that the hyperpolarizations observed in MSNs were because of decreased tonic activation of M1 muscarinic receptors, resulting in an increase in Kir2 conductances. Evoked GABAergic responses of MSNs were reversibly decreased by ethanol with no change in paired-pulse ratio. Furthermore, ethanol impaired the ability of thalamostriatal inputs to inhibit a subsequent corticostriatal glutamatergic response in MSNs. These results offer the first comprehensive description of the highly cell type-specific effects of ethanol on striatal neurons and provide a cellular basis for the interpretation of ethanol influence on a brain area crucially involved in the motor and decisional impairment caused by this drug.

  6. Effect of Negative Pressure on Yeast Metabolism in Coupling Process of Ethanol Fermentation and Separation%乙醇发酵分离耦合过程中负压对酵母代谢的影响

    Institute of Scientific and Technical Information of China (English)

    谢慧; 刘杰; 王风芹; 杜风光; 宋安东


    The effects of negative pressure on yeast reproductive capacity, yeast morphology, fermentation performance, fermentation byproduct in the coupling process of ethanol fermentation and separation were studied. The results showed that negative pressure had a certain influence on the reproductive capacity and morphology of yeast by plate and microscopic observation, and the maximum ethanol concentration and ethanol productivity of the samples in negative pressure treatment were higher than those in the control. During pumping the air, a part of sugar was transformed into cell maintenance energy, which was proved by metabolic flux analysis. According to the results of fermentation experiment, the yeast fermentation kinetic model was established.%研究了负压对酵母繁殖力、酵母形态、发酵性能、发酵副产物等的影响,结果表明:通过平板和显微镜观察,发现负压对酵母的繁殖力和形态有一定的影响;抽样的最大乙醇浓度、乙醇生产力比对照高;抽压过程中有一部分糖被消耗转化为茵体的维持能;并根据发酵结果,对菌体生长、糖消耗、CO2生成、乙醇生成进行了曲线拟合.

  7. A novel in situ gas stripping-pervaporation process integrated with acetone-butanol-ethanol fermentation for hyper n-butanol production. (United States)

    Xue, Chuang; Liu, Fangfang; Xu, Mengmeng; Zhao, Jingbo; Chen, Lijie; Ren, Jiangang; Bai, Fengwu; Yang, Shang-Tian


    Butanol is considered as an advanced biofuel, the development of which is restricted by the intensive energy consumption of product recovery. A novel two-stage gas stripping-pervaporation process integrated with acetone-butanol-ethanol (ABE) fermentation was developed for butanol recovery, with gas stripping as the first-stage and pervaporation as the second-stage using the carbon nanotubes (CNTs) filled polydimethylsiloxane (PDMS) mixed matrix membrane (MMM). Compared to batch fermentation without butanol recovery, more ABE (27.5 g/L acetone, 75.5 g/L butanol, 7.0 g/L ethanol vs. 7.9 g/L acetone, 16.2 g/L butanol, 1.4 g/L ethanol) were produced in the fed-batch fermentation, with a higher butanol productivity (0.34 g/L · h vs. 0.30 g/L · h) due to reduced butanol inhibition by butanol recovery. The first-stage gas stripping produced a condensate containing 155.6 g/L butanol (199.9 g/L ABE), which after phase separation formed an organic phase containing 610.8 g/L butanol (656.1 g/L ABE) and an aqueous phase containing 85.6 g/L butanol (129.7 g/L ABE). Fed with the aqueous phase of the condensate from first-stage gas stripping, the second-stage pervaporation using the CNTs-PDMS MMM produced a condensate containing 441.7 g/L butanol (593.2 g/L ABE), which after mixing with the organic phase from gas stripping gave a highly concentrated product containing 521.3 g/L butanol (622.9 g/L ABE). The outstanding performance of CNTs-PDMS MMM can be attributed to the hydrophobic CNTs giving an alternative route for mass transport through the inner tubes or along the smooth surface of CNTs. This gas stripping-pervaporation process with less contaminated risk is thus effective in increasing butanol production and reducing energy consumption.

  8. Selection of barley grain affects ruminal fermentation, starch digestibility, and productivity of lactating dairy cows. (United States)

    Silveira, C; Oba, M; Yang, W Z; Beauchemin, K A


    The objective of this study was to evaluate the effects of 2 lots of barley grain cultivars differing in expected ruminal starch degradation on dry matter (DM) intake, ruminal fermentation, ruminal and total tract digestibility, and milk production of dairy cows when provided at 2 concentrations in the diet. Four primiparous ruminally cannulated (123 +/- 69 d in milk; mean +/- SD) and 4 multiparous ruminally and duodenally cannulated (46 +/- 14 d in milk) cows were used in a 4 x 4 Latin Square design with a 2 x 2 factorial arrangement of treatments with 16-d periods. Primiparous and multiparous cows were assigned to different squares. Treatments were 2 dietary starch concentrations (30 vs. 23% of dietary DM) and 2 lots of barley grain cultivars (Xena vs. Dillon) differing in expected ruminal starch degradation. Xena had higher starch concentration (58.7 vs. 50.0%) and greater in vitro 6-h starch digestibility (78.0 vs. 73.5%) compared with Dillon. All experimental diets were formulated to supply 18.3% crude protein and 20.0% forage neutral detergent fiber. Dry matter intake and milk yield were not affected by treatment. Milk fat concentration (3.55 vs. 3.29%) was greater for cows fed Dillon compared with Xena, but was not affected by dietary starch concentration. Ruminal starch digestion was greater for cows fed high-starch diets compared with those fed low-starch diets (4.55 vs. 2.49 kg/d), and tended to be greater for cows fed Xena compared with those fed Dillon (3.85 vs. 3.19 kg/d). Ruminal acetate concentration was lower, and propionate concentration was greater, for cows fed Xena or high-starch diets compared with cows fed Dillon or low-starch diets, respectively. Furthermore, cows fed Xena or high-starch diets had longer duration that ruminal pH was below 5.8 (6.6 vs. 4.0 and 6.4 vs. 4.2 h/d) and greater total tract starch digestibility (94.3 vs. 93.0 and 94.3 vs. 93.0%) compared with cows fed Dillon or low-starch diets, respectively. These results

  9. 乙醇对酱油发酵体系中蛋白酶系的影响研究%Effect of Ethanol on the Proteases in Soy Sauce Fermentation System

    Institute of Scientific and Technical Information of China (English)



    通过控制酒精发酵来研究乙醇对酱油发酵体系中蛋白酶系的影响,发现乙醇对碱性蛋白酶的稳定性影响很大,特别是在发酵温度为30℃、pH 5.0、乙醇含量在2%以上时碱性蛋白酶失活加剧;乙醇对中性蛋白酶活力的抑制作用较明显,特别是在乙醇含量大于2%以后,其活力急剧下降,最低降到38%.研究结果显示,适度的酒精发酵对氨基氮生成和原料蛋白利用率有益,但过度的酒精发酵则会起到相反的作用.%The effect of ethanol on the proteases in soy sauce fermentation system was studied through control of alcoholic fermentation, Ethanol has a greater impact on stability of alkaline protease, the activity of alkaline protease declined rapidly when fermentation temperature was 30 °C, pH 5.0, and ethanol content more than 2%. Ethanol also has a significant impact on the activity of neutral protease, the activity of neutral protease declined rapidly when ethanol content more than 2%, and the activity dropped to 38%. The results showed that moderate alcohol fermentation benefit of the generation of amino nitrogen and the utilization of protein bring by raw materials, but excessive alcohol fermentation does the opposite effect.

  10. Production of hydrogen, ethanol and volatile fatty acids through co-fermentation of macro- and micro-algae. (United States)

    Xia, Ao; Jacob, Amita; Tabassum, Muhammad Rizwan; Herrmann, Christiane; Murphy, Jerry D


    Algae may be fermented to produce hydrogen. However micro-algae (such as Arthrospira platensis) are rich in proteins and have a low carbon/nitrogen (C/N) ratio, which is not ideal for hydrogen fermentation. Co-fermentation with macro-algae (such as Laminaria digitata), which are rich in carbohydrates with a high (C/N) ratio, improves the performance of hydrogen production. Algal biomass, pre-treated with 2.5% dilute H2SO4 at 135°C for 15min, effected a total yield of carbohydrate monomers (CMs) of 0.268g/g volatile solids (VS). The CMs were dominating by glucose and mannitol and most (ca. 95%) were consumed by anaerobic fermentative micro-organisms during subsequent fermentation. An optimal specific hydrogen yield (SHY) of 85.0mL/g VS was obtained at an algal C/N ratio of 26.2 and an algal concentration of 20g VS/L. The overall energy conversion efficiency increased from 31.3% to 54.5% with decreasing algal concentration from 40 to 5 VS g/L.

  11. Mechanisms affecting the infiltration and distribution of ethanol-blended gasoline in the vadose zone. (United States)

    McDowell, Cory J; Powers, Susan E


    One- and two-dimensional experiments were conducted to examine differences in the behavior of gasoline and gasohol (10% ethanol by volume) as they infiltrate through the unsaturated zone and spread at the capillary fringe. Ethanol in the spilled gasohol quickly partitions into the residual water in the vadose zone and is retained there as the gasoline continues to infiltrate. Under the conditions tested, over 99% of the ethanol was initially retained in the vadose zone. Depending on the volume of gasoline spilled and the depth to the water table, this causes an increase in the aqueous-phase saturation and relative permeability, thus allowing the ethanol-laden water to drain into the gasoline pool. Under the conditions tested, the presence of ethanol does not have a significant impact on the overall size or shape of the resulting gasoline pool at the capillary fringe. Residual gasoline saturations in the vadose zone were significantly reduced however because of reduced surface and interfacial tensions associated with high ethanol concentrations. The flux of ethanol in the effluent of the column ranged from 1.4 x 10(-4) to 4.5 x 10(-7) g/(cm2 min) with the LNAPL and from 6 x 10(-3) to 3.0 x 10(-4) g/(cm2 min) after water was introduced to simulate rain infiltration. The experimental results presented here illustrate that the dynamic effects of ethanol partitioning into the aqueous phase in the vadose zone create an initial condition that is significantly different than previously understood.

  12. Pretreatment of bamboo by ultra-high pressure explosion with a high-pressure homogenizer for enzymatic hydrolysis and ethanol fermentation. (United States)

    Jiang, Zehui; Fei, Benhua; Li, Zhiqiang


    Bamboo shoots, 2- and 5-year-old bamboo were treated by using a homogenizer in a constant suspended state, a process termed as ultra-high pressure explosion (UHPE). The bamboo powder was heated in 2% NaOH solution at 121°C, and then 100MPa UHPE-treated through a homogenizer. The results verified that UHPE changed the suspension solution of powder into a stick fluid. The contents of lignin were decreased significantly. The bamboo shoots and 2-year-old bamboo were completely hydrolyzed to glucose within 48h by enzymes loading of 15 FPU of cellulase and 30IU of β-glucosidase per gram glucan. Fermentation of enzymatic hydrolyzates with Saccharomyces cerevisiae resulted in about 89.7-95.1% of the theoretical ethanol yield after 24h. Therefore, NaOH+UHPE is argued to be a potential alternative technology for pretreatment of bamboo.

  13. 玉米原料超高浓度酒精发酵%Very High Gravity Ethanol Fermentation Using Whole Ground Corn

    Institute of Scientific and Technical Information of China (English)

    许宏贤; 段钢


    以全磨玉米为原料,研究了超高浓度条件下传统工艺与生料工艺的黏度变化。采用传统工艺,在超高浓度条件下,物料的糊化、液化会变得非常困难。而采用生料工艺,黏度始终维持在合理的水平。对高浓度传统工艺和生料工艺发酵的结果进行对比,证明生料工艺可以产出更多的酒精;对超高底物浓度(35%绝对干物)生料发酵时采用温度梯度控制,使用市售酒精干酵母,在98 h内发酵醪液酒精浓度可达20%以上。%Viscosity is one key bottleneck of high gravity fermentation.The viscosity profiles of both conventional process and no-cook process are investigated using whole ground corn as the raw material.At very high dry solid concentration,it is found that during conventional hot cooking process,the gelatinization and liquefaction become very hard to handle while there is no viscosity issue for no cook process.In addition,the no cook process generate more ethanol than that from conventional process during high gravity fermentation;with the help of raw starch hydrolyzing enzymes,together with commercial dry yeast and temperature staging strategy,ethanol concentration was able to reach up to 20%(v/v) within 98h.

  14. Enzymatic hydrolysis and ethanol fermentation of high dry matter wet-exploded wheat straw at low enzyme loading

    DEFF Research Database (Denmark)

    Georgieva, T.I.; Hou, Xiaoru; Hilstrøm, Troels


    Wheat straw was pretreated by wet explosion using three different oxidizing agents (H2O2, O-2, and air). The effect of the pretreatment was evaluated based on glucose and xylose liberated during enzymatic hydrolysis. The results showed that pretreatment with the use of O-2 as oxidizing agent...... viscosity of the material, higher inhibition of the enzymes, and fermenting microorganism. The wet-explosion pretreatment method enabled relatively high yields from both enzymatic hydrolysis and simultaneous saccharification and fermentation (SSF) to be obtained when performed on unwashed slurry with 14% DM...

  15. Metabolic flux analysis model for optimizing xylose conversion into ethanol by the natural C5-fermenting yeast Candida shehatae. (United States)

    Bideaux, Carine; Montheard, Julie; Cameleyre, Xavier; Molina-Jouve, Carole; Alfenore, Sandrine


    A metabolic flux analysis (MFA) model was developed to optimize the xylose conversion into ethanol using Candida shehatae strain. This metabolic model was compartmented and constructed with xylose as carbon substrate integrating the enzymatic duality of the first step of xylose degradation via an algebraic coefficient. The model included the pentose phosphate pathway, glycolysis, synthesis of major metabolites like ethanol, acetic acid and glycerol, the tricarboxylic acid cycle as well as the respiratory chain, the cofactor balance, and the maintenance. The biomass composition and thus production were integrated considering the major biochemical synthesis reactions from monomers to each constitutive macromolecule (i.e., proteins, lipids, polysaccharides, nucleic acids). The construction of the model resulted into a 122-linear equation system to be resolved. A first experiment allowed was to verify the accuracy of the model by comparing calculated and experimental data. The metabolic model was utilized to determine the theoretical yield taking into account oxido-reductive balance and to optimize ethanol production. The maximal theoretical yield was calculated at 0.62 Cmolethanol/Cmolxylose for an oxygen requirement of 0.33 moloxygen/molxylose linked to the cofactors of the xylose reductase. Cultivations in chemostat mode allowed the fine tuning of both xylose and oxygen uptakes and showed that lower was the oxygen/xylose ratio, higher was the ethanol production yield. The best experimental ethanol production yield (0.51 Cmolethanol/Cmolxylose) was obtained for an oxygen supply of 0.47 moloxygen/molxylose.

  16. Quantitative evaluation of yeast's requirement for glycerol formation in very high ethanol performance fed-batch process

    NARCIS (Netherlands)

    Pagliardini, Julien; Hubmann, Georg; Bideaux, Carine; Alfenore, Sandrine; Nevoigt, Elke; Guillouet, Stéphane E.


    Background: Glycerol is the major by-product accounting for up to 5% of the carbon in Saccharomyces cerevisiae ethanolic fermentation. Decreasing glycerol formation may redirect part of the carbon toward ethanol production. However, abolishment of glycerol formation strongly affects yeast's robustne

  17. KINETIKA FERMENTASI ASAM ASETAT (VINEGAR OLEH BAKTERI Acetobacter aceti B 127 DARI ETANOL HASIL FERMENTASI LIMBAH CAIR PULP KAKAO [Kinetics of Acetic Acid (Vinegar Fermentation By Acetobacter aceti B127 from Ethanol Produced by Fermentation of Liquid Waste of Cacao Pulp

    Directory of Open Access Journals (Sweden)

    M. Supli Effendi


    Full Text Available Acetic acid concentration is one of vinegar’s quality parameter. Acetic acid concentration in vinegar is influenced by the activity of acetic acid bacteria. This research studied the kinetics of anaerobic fermentation of liquid waste of cacao pulp by Saccharomyces cerevisiae R60 to produce ethanol and the kinetics of acetic acid fermentation from ethanol by Acetobacter aceti B127. The kinetics of acetic acid fermentation from ethanol by Acetobacter aceti B127 can be used as a basic of bioprocess design for aerobic fermentation in general and acetic acid fermentation from ethanol by Acetobacter aceti B127 in particular. Fermentation medium used was liquid waste of cocoa pulp with sugar content of 12.85%, and the addition of sucrosa and urea. The parameter observed was growth of Saccharomyces cerevisiae R60 and Acetobacter aceti B127, and chemical analysis including concentration of ethanol, total sugar and acetic acid, content. The research result showed that the  value was 0.048 hour-1, Y P was 0.676, Qp value was 0.033 hour-, and KLa value was 0.344, QO2.Cx value was 0.125 (mgO2L-1jam-1, Y X was s O2 0.378 (x 108selmL-1g-1¬¬O2, and dCT was 0.150 mgL-1hour-1. Concentration of acetic acid in the product was 4.24% or 42.4 gL-1

  18. The influence of Adh function on ethanol preference and tolerance in adult Drosophila melanogaster. (United States)

    Ogueta, Maite; Cibik, Osman; Eltrop, Rouven; Schneider, Andrea; Scholz, Henrike


    Preference determines behavioral choices such as choosing among food sources and mates. One preference-affecting chemical is ethanol, which guides insects to fermenting fruits or leaves. Here, we show that adult Drosophila melanogaster prefer food containing up to 5% ethanol over food without ethanol and avoid food with high levels (23%) of ethanol. Although female and male flies behaved differently at ethanol-containing food sources, there was no sexual dimorphism in the preference for food containing modest ethanol levels. We also investigated whether Drosophila preference, sensitivity and tolerance to ethanol was related to the activity of alcohol dehydrogenase (Adh), the primary ethanol-metabolizing enzyme in D. melanogaster. Impaired Adh function reduced ethanol preference in both D. melanogaster and a related species, D. sechellia. Adh-impaired flies also displayed reduced aversion to high ethanol concentrations, increased sensitivity to the effects of ethanol on postural control, and negative tolerance/sensitization (i.e., a reduction of the increased resistance to ethanol's effects that normally occurs upon repeated exposure). These data strongly indicate a linkage between ethanol-induced behavior and ethanol metabolism in adult fruit flies: Adh deficiency resulted in reduced preference to low ethanol concentrations and reduced aversion to high ones, despite recovery from ethanol being strongly impaired.

  19. Continuous ethanol fermentation at 45 C using Kluyveromyces marxianus IMB3 immobilized in Calcium alginate and kissiris

    Energy Technology Data Exchange (ETDEWEB)

    Love, G.; Gough, S.; Brady, D.; Barron, N.; Nigam, P.; Marchant, R.; McHale, A.P. [Biotechnology Research Group, School of Applied Biological and Chemical Sciences, University of Ulster (United Kingdom); Singh, D. [Microbiology Dept., Haryana Agricultural University, Hisar (India)


    The thermotolerant ethanol-producing yeast strain Kluyveromyces marxianus IMB3 was immobilized in calcium alginate and a 1:1 mixture of calcium alginate and the porous volcanic mineral, kissiris. Immobilized preparations were placed in fixed-bed column bioreactors and continuous ethanol production by systems containing both immobilized preparations was examined at 45 C with a 100 g/l glucose feed. The effect of residence time on product concentration, bioreactor efficiency and volumetric productivities have been examined and these were all higher in systems containing the alginate/kissiris mixed immobilization matrix. Maximum ethanol concentrations produced by the continuous system ranged between 46 and 48 g/l representing efficiencies of 90-94%. (orig.) With 1 tab., 13 refs.


    Directory of Open Access Journals (Sweden)

    Daniela Mikulíková


    Full Text Available Wheat grain samples from sixteen winter cultivars originated from four localities were evaluated and compared in traits related to ethanol production as grain yield, grain hardness, content of protein, starch and amylose, and α-amylase activity. Results obtained indicate significant differences between cultivars in amylose content, α-amylase activity, and grain hardness compared to grain yield, protein content, and starch content where differences were not significant. The amylose content, α-amylase activity, and grain hardness were affected by cultivar. Both testing methods for starch fermentation - separated hydrolysis and fermentation (SHF and simultaneous saccharification and fermentation (SSF revealed difference between cultivars in ethanol yield.

  1. The enhancement of butanol production by in situ butanol removal using biodiesel extraction in the fermentation of ABE (acetone-butanol-ethanol). (United States)

    Yen, Hong-Wei; Wang, Yi-Cheng


    High butanol accumulation is due to feedback inhibition which leads to the low butanol productivity observed in acetone-butanol-ethanol (ABE) fermentation. The aim of this study is to use biodiesel as an extractant for the in situ removal of butanol from the broth. The results indicate that adding biodiesel as an extractant at the beginning of fermentation significantly enhances butanol production. No significant toxicity of biodiesel on the growth of Clostridium acetobutylicum is observed. In the fed-batch operation with glucose feeding, the maximum total butanol obtained is 31.44 g/L, as compared to the control batch (without the addition of biodiesel) at 9.85 g/L. Moreover, the productivity obtained is 0.295 g/L h in the fed-batch, which is higher than that of 0.185 g/L h for the control batch. The in situ butanol removal by the addition of biodiesel has great potential for commercial ABE production.

  2. Saccharification of polysaccharide content of palm kernel cake using enzymatic catalysis for production of biobutanol in acetone-butanol-ethanol fermentation. (United States)

    Shukor, Hafiza; Abdeshahian, Peyman; Al-Shorgani, Najeeb Kaid Nasser; Hamid, Aidil Abdul; Rahman, Norliza A; Kalil, Mohd Sahaid


    In this work, hydrolysis of cellulose and hemicellulose content of palm kernel cake (PKC) by different types of hydrolytic enzymes was studied to evaluate monomeric sugars released for production of biobutanol by Clostridium saccharoperbutylacetonicum N1-4 (ATCC 13564) in acetone-butanol-ethanol (ABE) fermentation. Experimental results revealed that when PKC was hydrolyzed by mixed β-glucosidase, cellulase and mannanase, a total simple sugars of 87.81±4.78 g/L were produced, which resulted in 3.75±0.18 g/L butanol and 6.44±0.43 g/L ABE at 168 h fermentation. In order to increase saccharolytic efficiency of enzymatic treatment, PKC was pretreated by liquid hot water before performing enzymatic hydrolysis. Test results showed that total reducing sugars were enhanced to 97.81±1.29 g/L with elevated production of butanol and ABE up to 4.15±1.18 and 7.12±2.06 g/L, respectively which represented an A:B:E ratio of 7:11:1.

  3. Potentiation of gamma aminobutyric acid receptors (GABAAR by Ethanol: How are inhibitory receptors affected?

    Directory of Open Access Journals (Sweden)

    Benjamin eFörstera


    Full Text Available In recent years there has been an increase in the understanding of ethanol actions on the type A -aminobutyric acid chloride channel (GABAAR, a member of the pentameric ligand gated ion channels (pLGICs. However, the mechanism by which ethanol potentiates the complex is still not fully understood and a number of publications have shown contradictory results. Thus many questions still remain unresolved requiring further studies for a better comprehension of this effect. The present review concentrates on the involvement of GABAAR in the acute actions of ethanol and specifically focuses on the immediate, direct or indirect, synaptic and extra-synaptic modulatory effects. To elaborate on the immediate, direct modulation of GABAAR by acute ethanol exposure, electrophysiological studies investigating the importance of different subunits, and data from receptor mutants will be examined. We will also discuss the nature of the putative binding sites for ethanol based on structural data obtained from other members of the pLGICs family. Finally, we will briefly highlight the glycine gated chloride channel (GlyR, another member of the pLGIC family, as a suitable target for the development of new pharmacological tools.

  4. Effects of lignocellulose degradation products on ethanol fermentations using glucose and xylose by Kluyveromyces marxianus 1727%纤维素降解产物对 Kluyveromyces marxianus 1727共发酵葡萄糖和木糖的影响

    Institute of Scientific and Technical Information of China (English)

    王娜; 袁文杰; 韩锡铜; 白凤武; 徐永平


    研究纤维素酸水解产生的4种副产物乙酸、甲酸、糠醛、5-羟甲基糠醛及发酵产物乙醇对Kluyveromyces marxianus 1727共发酵葡萄糖和木糖的影响.结果表明:5.0 g/L乙酸和1.0 g/L甲酸对葡萄糖和木糖共发酵具有明显的抑制作用;1.0 g/L糠醛和5-羟甲基糠醛基本不影响K.marxianus 1727发酵葡萄糖,且能够被K.marxianus 1727转化为毒性相对较低的物质.由于5 -羟甲基糠醛的转化速率慢,对K.marxianus 1727发酵木糖的抑制程度大于糠醛.乙醇对K.marxianus 1727发酵木糖具有抑制作用,当乙醇质量浓度大于20 g/L时,生物量及木糖利用率约是对照的44%和70%.%The inhibitory effects of four lignocellulose degradation products and ethanol on glucose and xylose fermentation by Kluyveromyces marxianus 1727 were studied in batch cultures. Toxic compounds were added in variable concentrations, and subsequent inhibitions on growth and ethanol production were tested. The acetic acid and the formic acid were shown to be strong inhibitors of both glucose and xylose fermentation when they were added to the culture media at concentrations of 5.0 g/L and 1.0 g/L, respectively. Furfural and 5-hydroxylmethyl furfural at a concentration of 1 g/L did not affect glucose fermentation, and could be changed into relatively low toxic substances. The inhibition of 5-hydroxylmethyl furfural was serious on xylose fermentation than furfural due to the transformation of the 5-hydroxylmethyl slower than that of furfural. Ethanol was also shown to be strong inhibitors of xylose fermentation, when the ethanol concentration was more than 20 g/L, biomass and xylose transformation efficiencies were 44% and 70% of the control.

  5. Bioconversion of sawdust into ethanol using dilute sulfuric acid-assisted continuous twin screw-driven reactor pretreatment and fed-batch simultaneous saccharification and fermentation. (United States)

    Kim, Tae Hyun; Choi, Chang Ho; Oh, Kyeong Keun


    Ethanol production from poplar sawdust using sulfuric acid-assisted continuous twin screw-driven reactor (CTSR) pretreatment followed by simultaneous saccharification and fermentation (SSF) was investigated. Pretreatment with high acid concentration increased the cellulose content in the pretreated solid (74.9-76.9% in the range of 4.0-5.5wt.% H(2)SO(4)). The sugar content (XMG; xylan+mannan+galactan) in the treated-solid was 11.1-15.2% and 0.9-5.7% with 0.5wt.% and 7.0wt.%, respectively. The XMG recovery yield of the sample treated with 4.0wt.% H(2)SO(4) at 185°C was maximized at 88.6%. Enzymatic hydrolysis test showed a cellulose digestibility of 67.1%, 70.1%, and 73.6% with 15, 30, and 45FPU/g-cellulose, respectively. In the fed-batch SSF tests with initial enzyme addition, the ethanol yield of each stage almost reached a maximum at 28h, 48h, and 56h, respectively, with yields of 63.9% (16.5g/L), 78.4% (30.1g/L), and 81.7% (39.9g/L), respectively.

  6. Do new cellulolytic enzyme preparations affect the industrial strategies for high solids lignocellulosic ethanol production?

    DEFF Research Database (Denmark)

    Cannella, David; Jørgensen, Henning


    Production of ethanol from lignocellulosic materials has a promising market potential, but the process is still only at pilot/demonstration scale due to the technical and economical difficulties of the process. Operating the process at very high solids concentrations (above 20% dry matter—DM) has...... matter conditions. In this work the impact of selected enzyme preparation and processing strategy (SHF, presaccharification and simultaneous saccharification and fermentation—PSSF, and SSF) on final ethanol yield and overall performance was investigated with pretreated wheat straw up to 30% DM....... The experiments revealed that an SSF strategy was indeed better than SHF when applying an older generation enzyme cocktail (Celluclast-Novozym 188). In case of the newer product Cellic CTec 2, SHF resulted in 20% higher final ethanol yield compared to SSF. It was possible to close the mass balance around...

  7. Capture of carbon dioxide from ethanol fermentation by liquid absorption for use in biological production of succinic acid (United States)

    Previously it was shown that the gas produced in an ethanol fermentor using either corn or barley as feedstock could be sparged directly into an adjacent fermentor using Escherichia coli AFP184 to provide the CO2 required for succinic acid production. In the present investigation it has been demons...

  8. Spittlebug impacts on sugarcane quality and ethanol production

    Directory of Open Access Journals (Sweden)

    Gisele Cristina Ravaneli


    Full Text Available The objective of this work was to evaluate the impacts of spittlebug (Mahanarva fimbriolata attack on sugarcane quality and ethanol production. Technological and microbiological parameters of juice and fermentation process were evaluated in ten fermentation cycles and two harvest seasons. Treatments consisted of different spittlebug stalk damage levels: control, with 100% of apparently healthy stalks; medium, with 15% of damaged or dry stalks (DDS; high, with 30% of DDS; and very high, with 60% of DDS. Spittlebug attack caused significant losses in cane quality, reducing total soluble solids, sucrose content, total reducing sugars, and pH, and increasing total phenolic compounds, and total and volatile juice acidity. The fermentation process was also significantly affected, resulting in lower ethanol content in wine. There was an increase in acetaldehyde concentration in the distillate. The spittlebug attack caused negative impacts on sugarcane quality and fermentation process, and these impacts are stronger in late season harvests.

  9. Research on the Ethanol Produced from the Simultaneous Glycation and Fermentation of Cellulose%纤维素同步糖化发酵生产乙醇

    Institute of Scientific and Technical Information of China (English)

    孙武举; 翁海波; 李萍萍; 晋果果


    [目的]利用微生物方法生产乙醇,从而替代化石能源.[方法]土曲霉M11利用纤维素为原料产酶并糖化纤维素成还原糖,利用酿酒酵母发酵生成乙醇.[结果]通过对土曲霉M11生长条件的研究,确定了土曲霉M11的最佳培养时间是3d,最佳接种量为200μl,最适培养湿度为80%,最适培养温度为45℃,最适培养pH为3.0,此条件下可获得最大的产酶量.通过对糖化过程的研究,确定了纤维素酶的最适糖化温度为55℃,最适pH为5.0,此条件下可获得较高的还原糖量,且在酸性条件下酶活力较高,具有很好的热稳定性.通过发酵.还原糖量占原材料干重的62.42%,产生的乙醇占原材料干重的21.36%.[结论]此方法可以应用于工业发酵生产乙醇,有利于保护环境、降低成本、提高社会效益,有很好的应用价值.%[Objective] The ethanol was produced by means of microbiological processes for the replacing approach of energy source. [ Method] The reducing sugar was produced from the cellulose, which was saccharified by the enzyme that was from the cellulose as raw material was acted by Aspergillus teneus-Mll,,and the ethanol was produced based on the fermentation of yeast. [ Result] The experimental result indicated that the optimal culture condition of Aspergillus terreus-Mll growth was that the best time was 3 days,the best inoculation was 200 μl,the optimal culture humidity was 80% ,the optimum temperature was 45℃ and the optimal culture pH was 3.0,under which condition,the largest amount of enzyme-producing was available. And the experiment in the glycation process of cellulase showed the optimal temperature was 55 ℃ and the optimum pH was 5.0,under which condition the production of reducing sugar,which enzyme activity under acidic condition was higher and had good thermal stability,was relevantly high. By fermentation,the reduced sugar accounted for 62.42% of the dry weight of raw material and the produced ethanol

  10. Antimicrobial activity of tea as affected by the degree of fermentation and manufacturing season. (United States)

    Chou, C C; Lin, L L; Chung, K T


    Bacillus subtilis, Escherichia coli, Proteus vulgaris, Pseudomonas fluorescens, Salmonella sp. and Staphylococcus aureus were used to test the antimicrobial activity of tea flush extract and extracts of various tea products. Among the six test organisms, P. fluorescens was the most sensitive to the extracts, while B. subtilis was the least sensitive. In general, antimicrobial activity decreased when the extents of tea fermentation increased. The antimicrobial activities of tea flush extract and extracts of tea products with different extents of fermentation varied with test organisms. Tea flush and Green tea, the unfermented tea, exerted the strongest antimicrobial activity followed by the partially fermented tea products such as Longjing, Tieh-Kuan-Ying, Paochung, and Oolong teas. On the other hand, Black tea, the completely fermented tea, showed the least antimicrobial activity. It was also noted that extracts of Oolong tea prepared in summer exhibited the strongest antimicrobial activity, followed by those prepared in spring, winter and fall.

  11. Contribution to the optimisation of the association hydrolysis-fermentation for the ethanol production from raw wheat flour; Contribution a l'optimisation du couplage hydrolyse-fermentation en vue de la production d'ethanol a partir de broyats complets de ble

    Energy Technology Data Exchange (ETDEWEB)

    Montesinos, Th.


    This work describes the development of an ethanol production process from full crushed wheat. The first part is devoted to the determination of the kinetic parameters of the liquefaction, saccharification and fermentation steps. Liquefaction is performed during 2 hours at 95 deg. C and at pH 6.5 with a 120 L termamyl (amylase) dose of 0.2 g/kg of starch. 0.9 ml of 300 L AMG (amylo-glucosidase)/kg of starch are used for saccharification at 60 deg. C, pH 4.5 during 16 hours. The Michaelis-Menten constant (KM) of AMG for the wheat crushed substrate is of 10.5 g/l and the average speeds are of 6 and 30 g.l{sup -1}.h{sup -1} at 30 deg.C and 60 deg.C respectively. These first two steps are performed with a dry matter ratio of 30%. The alcoholic fermentation on hydrolyzed wort with 20% of dry matter supplemented with nitrogen and Saccharomyces cerevisiae lasts 15 h at 35 deg.C. The second part of the study concerns the optimization of the production process using a saccharification fermentation coupling process, called SSF: simultaneous saccharification fermentation. This coupling performed at 20% of dry matter, 35 deg.C and pH 4.5 with a AMG 300 L dose of 1.8 ml/kg of starch, lasts 19 h with an ethanol production of 69 g/l (yp/s = 0.46). This is the best result obtained so far. The third part describes the regulation mechanisms of the SSF process. Maltose, which is the major product of liquefaction, is an important effector which plays the double role of mixed inhibitor for the amylo-glucosidase and substrate for the yeast. The last part is devoted to the construction of a mathematical model for the phenomenology of the SSF process. The use of full crushed wheat as hydrolysis and fermentation substrate has permitted to show the impact of viscosity during the entire process. This viscosity is due to the presence of composed cellulose and pentosan brans. (J.S.)

  12. Starch conversion of ganyong (Canna edulis Ker. to bioethanol using acid hydrolysis and fermentation

    Directory of Open Access Journals (Sweden)



    Full Text Available Starch of ganyong is one of the sources of ethanol which is able to be produced by acid hydrolysis and fermentation process. It had high concentration of carbohydrate that is 80%, so it could produce glucose highly within acid hydrolysis process. The result showed that the optimal amount of reducing sugar had been produced by nitrate acid 7% (dextrose equivalent, DE = 28.4. Nevertheless, type and concentration of acid had no significantly correlation to reducing sugar yielded. The total amount of glucose had correlation to amount of ethanol, in fermentation process. The optimal amount of ethanol was yielded from 4.81% of glucose and it produced about 4.84% ethanol. The more amount of glucose was yielded the more ethanol was produced. Controlling pH every 12 hours did not affected to production of ethanol significantly.


    Directory of Open Access Journals (Sweden)



    Full Text Available The effects of fermentation on Ephestia cautella population and cocoa bean s quality in terms of moisture content, fungal population, the percentage of insect-damaged and mouldy beans, lipid and free fatty acid contents during storage were investigated together with the effects of £. cautella infestation on the quality of stored cocoa beans and weight loss. Fermented and unfermented cocoa beans with initial moisture contents of 7 or 9% were placed in ventilated plastic jars (Ikg/jar and stored for 6 months under room conditions. Seven larvae of £. cautella instar IV (2 males and 5 females were introduced in each jar at the beginning of storage. Untreated jars contained only cocoa beans. Population of £. cautella on fermented cocoa beans with either initial moisture content of 7 or 9% was lower than that on unfermented beans during storage. The population either on fermented or unfermented cocoa beans with initial moisture content of 7% was lower than that of 9%, and the population of all treatments increased during storage. Moisture content of all treatments either on cocoa beans with initial moisture contents of 7 or 9% had the same pattern. The percentage of insect-damaged beans on fermented cocoa beans was lower than that on unfermented cocoa beans after 5 to 6 months of storage. The damaged beans on fermented cocoa after 6 months of storage was not different than on unfermented beans after 4 months of storage. The weig ht loss either on fermented or unfermented cocoa beans with initial moisture content of 9% was higher than that with initial moisture content of 7%. The weight loss on fermented cocoa beans either with mois ture content of 7 or 9% was lower than that on unfermented beans during storage. The weight loss either on fermented or unfermented cocoa beans increased during storage. The percentage of mouldy beans on cocoa infested with £. cautella tended to increase during storage, while on beans not infested with the insect it

  14. Effects of simplified ethanol-wet bonding technique on immediate bond strength with normal versus caries-affected dentin (United States)

    Aggarwal, Vivek; Singla, Mamta; Sharma, Ritu; Miglani, Sanjay; Bhasin, Saranjit Singh


    Aim: The aim of the present study was to evaluate whether the use of simplified ethanol-wet bonding (EWB) technique improved the immediate microtensile bond strength (μTBS) between resin composite and caries-affected dentin (CAD). Materials and Methods: Twenty-four extracted carious human permanent molars were sectioned to expose the carious lesion. The carious dentin was excavated until CAD was exposed. The samples were divided into two groups: water-wet bonding with Adper Scotchbond Multi-Purpose and a simplified EWB (three 100% ethanol applications for 30 s each), followed by application of an experimental hydrophobic primer and restoration. The samples were vertically sectioned to produce 1 mm × 1 mm thick slabs. The normal dentin (ND) slabs and CAD slabs were identified and were subjected to μTBS evaluation. Slabs from four teeth (two from each group) were evaluated under microscope. Data were analyzed using two-way ANOVA and post hoc Holm–Sidak test at P < 0.05. Results: EWB improved the μTBS in ND but not in CAD group. The dentinal tubules in CAD group showed sclerotic activity with minimal or no hybrid layer. Conclusions: Simplified ethanol bonding does not improve the bond strength in CAD. PMID:27656059

  15. Process parameters affecting the sustainability of fermentative hydrogen production: A short-review

    Directory of Open Access Journals (Sweden)

    Carlos Dinamarca, Rune Bakke


    Full Text Available Anaerobic fermentation is regarded as the least energy intensive method for H2 production. Extensive literature on experimental attempts to achieve the highest possible theoretical yield (e.g. 4 mol H2/mol glucose is available. All published steady state, mixed culture studies show yields much lower than the theoretical maximums for the substrates applied. This article summarizes the influence of key process parameters (pH and buffer systems, temperature, H2 partial pressure, feed stock, and reactor configuration on fermentative hydrogen production. The following three requirements for successful Bio-H2 fermentation in mixed cultures are identified: (1 Maintain environmental conditions for the formation of oxidized products; (2 Optimize the relationship between biomass and hydrogen yields; and (3 Maintain unfavorable conditions for hydrogen consuming organisms. Fulfilling these requirements has not yet been achieved in stable continuous cultures, and it may not be achievable do to some fundamental limitation.

  16. Production of ethanol from Jerusalem artichoke flour by simultaneous saccharification and fermentation%同步糖化发酵菊芋生产酒精

    Institute of Scientific and Technical Information of China (English)

    张超; 王静; 唐波; 李奇建


    Mycelial pellets formed by Aspergillus niger A⁃15 were used to immobilize the alcohol producing yeast Saccharomyces cerevisiae C⁃15. The operated factors, such as agitation speed, temperature and mixed proportion of strains were studied. The optimal adsorption 66�9% was obtained when speed was 80 r/min, temperature was 40℃ and mixed proportion was 1∶10. With Jerusalem artichoke flour as substrate,12�8%( V/V) of ethanol was produced within 48 h of fermentation by simultaneous saccharification and fermentation using mycelial pellets at 30℃. And mycelial pellets could tolerate 19%(volume fraction) alcohol.%以黑曲霉A 15形成的菌丝球作为载体对酿酒酵母C 15进行固定化,研究各种因素对黑曲霉A 15菌丝球吸附率的影响。结果表明:在40℃、80 r/min、菌种个数混合比例为1∶10时,菌丝球对酵母的吸附可达到66�9%;以菊粉为底物,利用混合菌丝球进行同步糖化与发酵,30℃发酵48 h,发酵醪酒精体积分数达到12�8%,并且混合菌丝球可以耐受19%的酒精。

  17. Industrial PE-2 strain of Saccharomyces cerevisiae: from alcoholic fermentation to the production of recombinant proteins. (United States)

    Soares-Costa, Andrea; Nakayama, Darlan Gonçalves; Andrade, Letícia de Freitas; Catelli, Lucas Ferioli; Bassi, Ana Paula Guarnieri; Ceccato-Antonini, Sandra Regina; Henrique-Silva, Flavio


    Saccharomyces cerevisiae is the most important microorganism used in the ethanol fermentation process. The PE-2 strain of this yeast is widely used to produce alcohol in Brazil due to its high fermentation capacity. The aim of the present study was to develop an expression system for recombinant proteins using the industrial PE-2 strain of S. cerevisiae during the alcoholic fermentation process. The protein chosen as a model for this system was CaneCPI-1, a cysteine peptidase inhibitor. A plasmid containing the CaneCPI-1 gene was constructed and yeast cells were transformed with the pYADE4_CaneCPI-1 construct. To evaluate the effect on fermentation ability, the transformed strain was used in the fermentation process with cell recycling. During the nine-hour fermentative cycles the transformed strain did not have its viability and fermentation ability affected. In the last cycle, when the fermentation lasted longer, the protein was expressed probably at the expense of ethanol once the sugars were exhausted. The recombinant protein was expressed in yeast cells, purified and submitted to assays of activity that demonstrated its functionality. Thus, the industrial PE-2 strain of S. cerevisiae can be used as a viable system for protein expression and to produce alcohol simultaneously. The findings of the present study demonstrate the possibility of producing recombinant proteins with biotechnological applications during the ethanol fermentation process.

  18. Hydrogen production from cheese whey with ethanol-type fermentation: effect of hydraulic retention time on the microbial community composition. (United States)

    Rosa, Paula Rúbia Ferreira; Santos, Samantha Christine; Sakamoto, Isabel Kimiko; Varesche, Maria Bernadete Amâncio; Silva, Edson Luiz


    The effects of different hydraulic retention times (HRTs) of 4, 2, and 1h and varying sources of inoculum (sludge from swine and sludge from poultry) on the hydrogen production in two anaerobic fluidized bed reactors (AFBRs) were evaluated. Cheese whey was used as a substrate, and 5000mgCODL(-1) was applied. The highest hydrogen yield (HY) of 1.33molmol(-1) lactose and highest ethanol yield (EtOHY) of 1.22molEtOHmol(-1) lactose were obtained at the highest HRT (4h). When the reactors were operated at an HRT of 1h, methane (0.68LCH4h(-1)L(-1)) was produced concurrently with hydrogen (0.51LH2h(-1)L(-1)). The major metabolites observed were soluble ethanol, methanol, acetic acid, and butyric acid. Cloning of the 16S rRNA gene sequences indicated that the microbial community were affiliated with the genera Selenomonas sp. (69% of the sequences), and Methanobacterium sp. (98% of the sequences).

  19. Artificial symbiosis for acetone-butanol-ethanol (ABE) fermentation from alkali extracted deshelled corn cobs by co-culture of Clostridium beijerinckii and Clostridium cellulovorans (United States)


    Background Butanol is an industrial commodity and also considered to be a more promising gasoline substitute compared to ethanol. Renewed attention has been paid to solvents (acetone, butanol and ethanol) production from the renewable and inexpensive substrates, for example, lignocellulose, on account of the depletion of oil resources, increasing gasoline prices and deteriorating environment. Limited to current tools for genetic manipulation, it is difficult to develop a genetically engineered microorganism with combined ability of lignocellulose utilization and solvents production. Mixed culture of cellulolytic microorganisms and solventogenic bacteria provides a more convenient and feasible approach for ABE fermentation due to the potential for synergistic utilization of the metabolic pathways of two organisms. But few bacteria pairs succeeded in producing biobutanol of high titer or high productivity without adding butyrate. The aim of this work was to use Clostridium cellulovorans 743B to saccharify lignocellulose and produce butyric acid, instead of adding cellulase and butyric acid to the medium, so that the soluble sugars and butyric acid generated can be subsequently utilized by Clostridium beijerinckii NCIMB 8052 to produce butanol in one pot reaction. Results A stable artificial symbiotic system was constructed by co-culturing a celluloytic, anaerobic, butyrate-producing mesophile (C. cellulovorans 743B) and a non-celluloytic, solventogenic bacterium (C. beijerinckii NCIMB 8052) to produce solvents by consolidated bioprocessing (CBP) with alkali extracted deshelled corn cobs (AECC), a low-cost renewable feedstock, as the sole carbon source. Under optimized conditions, the co-culture degraded 68.6 g/L AECC and produced 11.8 g/L solvents (2.64 g/L acetone, 8.30 g/L butanol and 0.87 g/L ethanol) in less than 80 h. Besides, a real-time PCR assay based on the 16S rRNA gene sequence was performed to study the dynamics of the abundance of each strain

  20. 探索一种新型生物发酵途径生产乙醇%A Novel Method of Ethanol Fermentation from Biomass Resources

    Institute of Scientific and Technical Information of China (English)

    黄立; 黄潇; 董元楷; 邢芸; 葛驰宇; 刘景晶; 曹荣月


    在质粒pUC19中插入菊欧氏杆菌pehX启动子,并与全合成的运动发酵单胞菌的丙酮酸脱羧酶基因(pdc),乙醇脱氢酶基因(adhB)串联,构建pUC1 9-pdc-adhB乙醇发酵重组克隆,转化大肠杆菌DH5α,经气相色谱检测,在大肠杆菌中乙醇的表达量达到o.85%.菊欧氏杆菌富含多种纤维素酶,与一些仅可利用基本糖类作为碳源的大肠杆菌等相比,其可以利用纤维素作为碳源.本实验设计将pUC19-pdc-adhB乙醇发酵重组克隆转化至菊欧氏杆菌,尝试用氯化钙、电击等转化方法,但均没有获得转化子.提示需要寻找新的转化方法或者将pdc和adhB基因整合到菊欧氏杆菌的基因组中以使其能产生乙醇.%The clone of ethanol fermentation was constructed by pUC19 which carried pehX promoter from Eruinia chrysanthemi and codon-replaced pyruvate decarboxylase gene(pdc) and alcohol dehydrogenase gene(adhB) from Zymomonas mobilis. After the new constructed clone was transformed into E. Coli DH5a,the ethanol content of the E. Coli DH5ethanol for commercial practice.

  1. Raman Spectroscopic Profile of Ethanol Fermentation in High Gravity Cassava Starch Brewing%浓醪乙醇发酵的单细胞拉曼光谱表征

    Institute of Scientific and Technical Information of China (English)

    李自达; 赖钧灼; 廖威; 刘军贤; 王桂文


    应用激光镊子拉曼光谱技术收集500 L发酵罐中木薯淀粉浓醪乙醇发酵过程底物、产物及酵母单细胞的拉曼光谱,以期从单细胞水平为乙醇发酵提供新的认识.结果显示:1)拉曼光谱可以实时监测浓醪乙醇发酵过程底物与产物的变化;2)酵母细胞胞内物质的变化存在类似于产物变化的前发酵期、主发酵期和后发酵期3个阶段,但出现的时间要比产物变化晚约4 h;3)为适应浓醪发酵环境,酵母细胞的生理状态和胞内物质在不断地进行调整,随着环境乙醇浓度的升高,酵母细胞在胞内累积蛋白质和脂类物质,蛋白质二级结构逐渐变为以无规则卷曲为主;4)发酵后期,酵母细胞在胞内累积大量的嘌呤类物质,但细胞间含量存在异质性.上述结果表明,单细胞拉曼光谱技术提供了一种研究微生物发酵的新方法,可从新的角度获知乙醇发酵过程酵母细胞内外的变化信息.%Raman spectroscopy is used to characterize the process of ethanol fermentation and look into the Saccharomyces cerevisiae cells at single-cell level. The ethanol fermentation using high-concentration cassava starch as feedstock is processed in a 500 L fermentor and the Raman spectra of substrate, product and individual yeast cell are acquired by using laser tweezers Raman spectroscopy (LTRS). Major results are as follows: 1) Raman spectroscopy can monitor the dynamic changes of substrate and product during the ethanol fermentation; 2) the changes of intracellular components of yeast cells exhibit three stages, I. E., primary fermentation, main fermentation and later fermentation, which are similar to those of products, but there is a delay of about 4 hi 3) yeast cells amend its physiological state and intracellular compounds to adapt to the high osmotic stress at the initial stage and the high ethanol concentration at the later stage of fermentation. Random coiling dominates the secondary structure of

  2. Direct in situ butanol recovery inside the packed bed during continuous acetone-butanol-ethanol (ABE) fermentation. (United States)

    Wang, Yin-Rong; Chiang, Yu-Sheng; Chuang, Po-Jen; Chao, Yun-Peng; Li, Si-Yu


    In this study, the integrated in situ extraction-gas stripping process was coupled with continuous ABE fermentation using immobilized Clostridium acetobutylicum. At the same time, oleyl alcohol was cocurrently flowed into the packed bed reactor with the fresh medium and then recycled back to the packed bed reactor after removing butanol in the stripper. A high glucose consumption of 52 g/L and a high butanol productivity of 11 g/L/h were achieved, resulting in a high butanol yield of 0.21 g-butanol/g-glucose. This can be attributed to both the high bacterial activity for solvent production as well as a threefold increase in the bacterial density inside the packed bed reactor. Also reported is that 64 % of the butanol produced can be recovered by the integrated in situ extraction-gas stripping process. A high butanol productivity and a high glucose consumption were simultaneously achieved.

  3. Fermentation of lignocellulosic hydrolysates: Inhibition and detoxification

    Energy Technology Data Exchange (ETDEWEB)

    Palmqvist, E.


    The ethanol yield and productivity obtained during fermentation of lignocellulosic hydrolysates is decreased due to the presence of inhibiting compounds, such as weak acids, furans and phenolic compounds produced during hydrolysis. Evaluation of the effect of various biological, physical and chemical detoxification treatments by fermentation assays using Saccharomyces cerevisiae was used to characterise inhibitors. Inhibition of fermentation was decreased after removal of the non-volatile compounds, pre-fermentation by the filamentous fungus Trichoderma reesei, treatment with the lignolytic enzyme laccase, extraction with ether, and treatment with alkali. Yeast growth in lignocellulosic hydrolysates was inhibited below a certain fermentation pH, most likely due to high concentrations of undissociated weak acids. The effect of individual compounds were studied in model fermentations. Furfural is reduced to furfuryl alcohol by yeast dehydrogenases, thereby affecting the intracellular redox balance. As a result, acetaldehyde accumulated during furfural reduction, which most likely contributed to inhibition of growth. Acetic acid (10 g 1{sup -1}) and furfural (3 g 1{sup -1}) interacted antagonistically causing decreased specific growth rate, whereas no significant individual or interaction effects were detected by the lignin-derived compound 4-hydroxybenzoic acid (2 g 1{sup -1}). By maintaining a high cell mass density in the fermentor, the process was less sensitive to inhibitors affecting growth and to fluctuations in fermentation pH, and in addition the depletion rate of bioconvertible inhibitors was increased. A theoretical ethanol yield and high productivity was obtained in continuous fermentation of spruce hydrolysate when the cell mass concentration was maintained at a high level by applying cell recirculation 164 refs, 16 figs, 5 tabs

  4. Comparative study on processes of simultaneous saccharification and fermentation with high solid concentration for cellulosic ethanol production%高底物浓度纤维乙醇同步糖化发酵工艺的比较

    Institute of Scientific and Technical Information of China (English)

    常春; 王铎; 王林风; 马晓建


    The effects of various simultaneous saccharification fermentation (SSF) technologies on ethanol yield from cellulose were investigated. Using steam-exploded corn stalks as raw materials, five SSF technologies, including traditional SSF, SSF combined with preliminary enzymatic hydrolysis, fed-batch SSF coupled with preliminary enzymatic hydrolysis, SSF united with preliminary enzymatic hydrolysis coupling with vacuum separation and fed-batch SSF associated with preliminary enzymatic hydrolysis coupling with vacuum separation, were used for decomposition of the stalks. By comparing the fermentation process with higher solid concentration including 15% (mass) and 30% (mass), it was found that the fed-batch SSF combined with preliminary enzymatic hydrolysis is an effective way for raising substrate concentration. However, higher substrate concentration may lead to decrease of final ethanol yield. Moreover, SSF coupled with vacuum separation can weaken the product inhibition, and increase the ethanol yield. The ethanol productivity by the fed-batch SSF associated with preliminary enzymatic hydrolysis coupling with vacuum separation is 0. 40 g · L-1 · h-1, the highest value obtained, indicating that this technology can be a potential new technology.

  5. 甜高粱茎汁及茎渣同步糖化发酵工艺优化%Optimization of ethanol production from bagasse and juice of sweet sorghum stem by simultaneous saccharification and fermentation

    Institute of Scientific and Technical Information of China (English)

    陈朝儒; 王智; 马强; 张丽娜; 奚亚军; 顿宝庆; 李桂英; 路明; 杜风光


    为了提高甜高粱秸秆乙醇生产中茎汁和茎渣的利用,以甜高粱茎汁及其渣为发酵原料,对茎汁茎渣混合原料同步糖化乙醇发酵的工艺条件进行优化研究。采用Plackett-Burman(PB)筛选设计试验筛选出影响甜高粱茎秆渣汁同步糖化乙醇发酵的显著因素。采用响应面法建立了同步糖化发酵乙醇生产的乙醇产量数学模型。根据该模型进行了工艺参数的优化,以乙醇产量为指标,试验所得甜高粱茎秆渣汁同步糖化化乙醇发酵的优化工艺条件为:发酵温度36.58℃,混合纤维素酶添加量=23.5(FBU/mL)/35.25(CBU/mL),甜高粱渣汁质量体积比为8.2%,理论预测乙醇产量为89.2%,在此条件下进行验证试验,乙醇产量为88.98%,平均质量浓度,验证了数学模型的有效性,为提高甜高粱茎汁及茎渣混合原料同步糖化发酵产乙醇和提高发酵效率提供参考。%Ethanol production from energy crops which are renewable resources has gotten more and more attentions because of the energy crisis and environmental pollution. Sweetsorghum is considered as the most promising energy crop for the production of ethanol. Sweetsorghum stem is usually used to ferment ethanol, one of which is the liquid-state fermentation with the juice of sorghum stem. But a lot of bagasse of sorghum stem is discarded as wastes. The bagasse can be used as the supplemental materials of the fermentation of the juice. So it is absolutely necessary to study on the optimization of ethanol production with the bagasse and juice of the sorghum stem by simultaneous saccharification and fermentation (SSF). The response surface is an effective method to optimize the operating parameters of the SSF for the maximum ethanol yield. In this study, the Plackett-burman design was adopted to select the significant factors from 8 variables which influenced the ethanol yield and its concentration. The results indicated the ethanol

  6. Dilute H{sub 2}SO{sub 4}-catalyzed hydrothermal pretreatment to enhance enzymatic digestibility of Jatropha curcas fruit hull for ethanol fermentation

    Energy Technology Data Exchange (ETDEWEB)

    Marasabessy, Ahmad [Wageningen Univ. (Netherlands). Agrotechnology and Food Sciences Group; Rijksuniversiteit Groningen (Netherlands). Dept. of Chemical Engineering; Agency for the Assessment and Application of Technology (BPPT), Jakarta (Indonesia); Kootstra, A. Maarten J. [Wageningen Univ. (Netherlands). Agrotechnology and Food Sciences Group; Wageningen Univ. (Netherlands). Bioprocess Engineering Group; Sanders, Johan P.M.; Westhuis, Ruud A. [Wageningen Univ. (Netherlands). Agrotechnology and Food Sciences Group


    Dilute sulfuric acid pretreatment of the Jatropha curcas fruit hull at high temperatures (140 C to 180 C) performed in a 110-mL stainless steel reactor was investigated to enhance the enzymatic digestibility of its lignocellulosic components. Carbohydrates accounted for 43% of the dry matter of the J. curcas fruit hull biomass. The goal of the study was to optimize the pretreatment conditions (acid concentration, time, and temperature) in order to obtain the highest sugar yield after subsequent enzymatic hydrolysis. A Box-Behnken design was applied to the experimental setup in order to reduce the number of experiments. The optimal pretreatment conditions are 30-min incubations at a temperature of 178 C with a sulfuric acid concentration of 0.9% (w/v). Using these pretreatment conditions for a fruit solid loading of 9.52% followed by a 24-h enzymatic hydrolysis resulted in a liberation of 100% of all pentoses present (71% yield and 29% degradation to furfural) and 83% of the hexoses (78% yield and 5% degradation to 5-hydroxymethylfurfural). The simultaneous saccharification and fermentation experiment showed that acid-pretreated fruit hull can be used as a substrate for Saccharomyces cerevisiae to produce ethanol. (orig.)

  7. De-ashing treatment of corn stover improves the efficiencies of enzymatic hydrolysis and consequent ethanol fermentation. (United States)

    He, Yanqing; Fang, Zhenhong; Zhang, Jian; Li, Xinliang; Bao, Jie


    In this study, corn stover with different ash content was pretreated using dry dilute acid pretreatment method at high solids loading of 67% (w/w). The results indicate that the hydrolysis yield of corn stover is increased from 43.30% to 70.99%, and ethanol yield is increased from 51.74% to 73.52% when ash is removed from 9.60% to 4.98%. The pH measurement of corn stover slurry indicates that the decrease of pretreatment efficiency is due to the neutralization of sulfuric acid by alkaline compounds in the ash. The elemental analysis reveals that the ash has the similar composition with the farmland soil. This study demonstrates the importance of ash removal from lignocellulose feedstock under high solids content pretreatment.

  8. 动态通量平衡分析模拟酿酒酵母乙醇发酵工艺%Dynamic Flux Balance Analysis of Bio-ethanol Fermentation Simulation by S. cerevisiae

    Institute of Scientific and Technical Information of China (English)

    屠纪民; 孙来玉; 周国庆; 邵文琦; 钱坤; 于岚


    Bio-ethanol is a kind of safe, clean and high efficiency energy. S. cerevisiae has been widely used in bio-ethanol fermentation be-cause of its specific physiological properties. Flux balance analysis is a constraint-based computational tool using genome-scale metabolic net-work to predict intracellular fluxes. In this study, the dynamic flux balance analysis was used to simulate key parameters in bio-ethanol biopro-cess by using glucose as the unique carbon resource, such as biomass, residual glucose concentration and ethanol productivity. The affordable difference between simulated values and measured values indicated that this model could be successfully applied in this simple bioprocess. This work not only provided a computational simulation method in the prediction of bio-ethanol bioprocess, but also established the foundation of the theoretical simulation of ligno-cellulosic bio-ethanol fermentation.%生物乙醇是一种高效、清洁、安全的能源。酿酒酵母(S. cerevisiae)由于其生理特性而在生物乙醇发酵中广泛应用。利用动态通量平衡分析(DFBA)预测模拟了利用葡萄糖发酵产乙醇工艺中的关键参数,生物量、残糖浓度和乙醇生成。预测值与发酵实测值能够较好吻合。该方法为发酵工艺优化提供了计算机模拟优化的方法,也为利用其他底物,如纤维素、木糖等生物质发酵乙醇的理论模拟提供基础。

  9. High ethanol producing derivatives of Thermoanaerobacter ethanolicus (United States)

    Ljungdahl, Lars G.; Carriera, Laura H.


    Derivatives of the newly discovered microorganism Thermoanaerobacter ethanolicus which under anaerobic and thermophilic conditions continuously ferment substrates such as starch, cellobiose, glucose, xylose and other sugars to produce recoverable amounts of ethanol solving the problem of fermentations yielding low concentrations of ethanol using the parent strain of the microorganism Thermoanaerobacter ethanolicus are disclosed. These new derivatives are ethanol tolerant up to 10% (v/v) ethanol during fermentation. The process includes the use of an aqueous fermentation medium, containing the substrate at a substrate concentration greater than 1% (w/v).

  10. A dynamic flux balance model and bottleneck identification of glucose, xylose, xylulose co-fermentation in Saccharomyces cerevisiae (United States)

    Economically viable production of lignocellulosic ethanol requires efficient conversion of feedstock sugars to ethanol. Saccharomyces cerevisiae cannot ferment xylose, the main five-carbon sugars in biomass, but can ferment xylulose, an enzymatically derived isomer. Xylulose fermentation is slow rel...

  11. Identification and characterization of filamentous fungus during xylose fermentation for ethanol production%木糖发酵产乙醇丝状真菌的鉴定及发酵特性

    Institute of Scientific and Technical Information of China (English)

    范金霞; 杨谦; 姚琳; 陈刚


    At present,yeast is the main microorganism involved in ethanol production using xylose as carbon source.The filamentous fungi have been less studied compared to yeast.Duchenne tube and ethanol yield assay methods were applied to screen different microbes for xylose fermentation.The microorganism producing the highest amount of ethanol was identified by microscopy and 18s rRNA amplification and analysis.Fermentation assays of this microorganism were studied by the Potassium dichromate method.The screening results showed that the organism code named cs-28 was Fusarium oxysporum.It was found that this fungus could ferment xylose,glucose,sucrose and corn stalk to produce ethanol.The optimal nitrogen source was yeast extract.The ethanol production rate was highest at initial pH 6.0 and 30 ℃,when initial xylose concentration was 20 g·L-1.Thus,cs-28 can be used as a new strain for transformation of cellulose materials to ethanol.Moreover,characterization of cs-28 on xylose fermentation can be applied in technological advancement.%针对目前对丝状真菌的木糖发酵研究较少的现状,应用杜氏管发酵法初筛和发酵测定法复筛对不同环境的土壤样品进行菌株的筛选,并采用显微镜观察和18S rRNA序列扩增分析对菌种进行鉴定;用重铬酸钾法对菌株的发酵特性进行研究.结果表明:筛选到一株能发酵木糖的丝状真菌,命名为cs-28;经形态学和生物学鉴定为尖孢镰刀菌(Fusarium oxysporum);它不仅能发酵木糖,同时也能利用葡萄糖、蔗糖和玉米秸秆等多种发酵碳源;其最适氮源为酵母提取物;在温度为30℃、初始pH值为6.0、初始木糖质量浓度为20 g·L-

  12. Cellulose ethanol is ready to go

    Energy Technology Data Exchange (ETDEWEB)

    Hladik, M. [Iogen Corp., Ottawa, ON (Canada)


    Ottawa-based Iogen Corporation is a leader in industrial biotechnology with a focus on cellulose-based enzyme technology. The company designed and operates the world's first and largest cellulose ethanol demonstration facility making ethanol from biomass. This presentation described Iogen's cellulose ethanol demonstration facility and outlined the innovative process in which enzymes prepare the plant fibres for fermentation, distillation and finally conversion to cellulose ethanol fuel. Hydrolysis and fermentation are achieved using a multi-stage hydrolysis process. It is anticipated that biorefineries will use the residues from locally grown agriculture to produce the ethanol, but stakeholder alliances will have to be built in order to form the elements of commercialization. Feedstocks, government policy, infrastructure issues, investment climate and ethanol sales all contribute to the success of a commercial plant. An assessment of preliminary global feedstock availability was presented with reference to total wheat, coarse grains, barley, oats, rye, sorghum, rice straw and sugar cane production. To date, the use of cellulose ethanol fuel has been demonstrated in vehicle trials in Bonn, Germany, as well as fleet vehicles operated by Natural Resources Canada and Agriculture Canada. Sample feedstock basins in Germany, Canada and the United States were highlighted. The supply of cellulose feedstock is large enough to contribute significantly to reductions in fossil fuel consumption. The United States Department of Energy claims that cellulose ethanol could displace over 30 per cent of the current petroleum consumption in the United States, and that land resources in the United States are capable of producing a sustainable supply of biomass. However, technology, financing and government policies are the factors which currently affect the commercialization of emerging technologies. tabs., figs.

  13. Jilebi 2: Flowability, pourability and pH of batter as affected by fermentation


    Chakkaravarthi, A.; Kumar, H. N. Punil; Bhattacharya, Suvendu


    Fermentation of batter is an integral part of the preparation of jilebi, a traditional ready-to-eat sweet product of Indian sub-continent. The flowability and pourability of batter are crucial for forming jilebi strands during frying. Flowability and pourability have been determined from simulation studies based on the movement of batter on an inclined surface and the exit from an orifice, respectively; simple gadgets have been designed to determine these two characteristics along with provid...

  14. Mutations in Durum Wheat SBEII Genes affect Grain Yield Components, Quality, and Fermentation Responses in Rats. (United States)

    Hazard, Brittany; Zhang, Xiaoqin; Naemeh, Mahmoudreza; Hamilton, M Kristina; Rust, Bret; Raybould, Helen E; Newman, John W; Martin, Roy; Dubcovsky, Jorge


    Increased amylose in wheat (Triticum ssp.) starch is associated with increased resistant starch, a fermentable dietary fiber. Fermentation of resistant starch in the large intestine produces short-chain fatty acids that are associated with human health benefits. Since wheat foods are an important component of the human diet, increases in amylose and resistant starch in wheat grains have the potential to deliver health benefits to a large number of people. In three replicated field trials we found that mutations in starch branching enzyme II genes (SBEIIa and SBEIIb) in both A and B genomes (SBEIIa/b-AB) of durum wheat [T. turgidum L. subsp. durum (Desf.) Husn.] resulted in large increases of amylose and resistant starch content. The presence of these four mutations was also associated with an average 5% reduction in kernel weight (P = 0.0007) and 15% reduction in grain yield (P = 0.06) compared to the wild type. Complete milling and pasta quality analysis showed that the mutant lines have an acceptable quality with positive effects on pasta firmness and negative effects on semolina extraction and pasta color. Positive fermentation responses were detected in rats (Rattus spp.) fed with diets incorporating mutant wheat flour. This study quantifies benefits and limitations associated with the deployment of the SBEIIa/b-AB mutations in durum wheat and provides the information required to develop realistic strategies to deploy durum wheat varieties with increased levels of amylose and resistant starch.

  15. Steamed and Fermented Ethanolic Extract from Codonopsis lanceolata Attenuates Amyloid-β-Induced Memory Impairment in Mice

    Directory of Open Access Journals (Sweden)

    Jin Bae Weon


    Full Text Available Codonopsis lanceolata (C. lanceolata is a traditional medicinal plant used for the treatment of certain inflammatory diseases such as asthma, tonsillitis, and pharyngitis. We evaluated whether steamed and fermented C. lanceolata (SFC extract improves amyloid-β- (Aβ- induced learning and memory impairment in mice. The Morris water maze and passive avoidance tests were used to evaluate the effect of SFC extract. Moreover, we investigated acetylcholinesterase (AChE activity and brain-derived neurotrophic factor (BDNF, cyclic AMP response element-binding protein (CREB, and extracellular signal-regulated kinase (ERK signaling in the hippocampus of mice to determine a possible mechanism for the cognitive-enhancing effect. Saponin compounds in SFC were identified by Ultra Performance Liquid Chromatography-Quadrupole-Time-of-Flight Mass Spectrometry (UPLC-Q-TOF-MS. SFC extract ameliorated amyloid-β-induced memory impairment in the Morris water maze and passive avoidance tests. SFC extract inhibited AChE activity and also significantly increased the level of CREB phosphorylation, BDNF expression, and ERK activation in hippocampal tissue of amyloid-β-treated mice. Lancemasides A, B, C, D, E, and G and foetidissimoside A compounds present in SFC were determined by UPLC-Q-TOF-MS. These results indicate that SFC extract improves Aβ-induced memory deficits and that AChE inhibition and CREB/BDNF/ERK expression is important for the effect of the SFC extract. In addition, lancemaside A specifically may be responsible for efficacious effect of SFC.

  16. Granular starch hydrolysis for fuel ethanol production (United States)

    Wang, Ping

    Granular starch hydrolyzing enzymes (GSHE) convert starch into fermentable sugars at low temperatures (≤48°C). Use of GSHE in dry grind process can eliminate high temperature requirements during cooking and liquefaction (≥90°C). In this study, GSHE was compared with two combinations of commercial alpha-amylase and glucoamylase (DG1 and DG2, respectively). All three enzyme treatments resulted in comparable ethanol concentrations (between 14.1 to 14.2% v/v at 72 hr), ethanol conversion efficiencies and ethanol and DDGS yields. Sugar profiles for the GSHE treatment were different from DG1 and DG2 treatments, especially for glucose. During simultaneous saccharification and fermentation (SSF), the highest glucose concentration for the GSHE treatment was 7% (w/v); for DG1 and DG2 treatments, maximum glucose concentration was 19% (w/v). GSHE was used in one of the fractionation technologies (enzymatic dry grind) to improve recovery of germ and pericarp fiber prior to fermentation. The enzymatic dry grind process with GSHE was compared with the conventional dry grind process using GSHE with the same process parameters of dry solids content, pH, temperature, time, enzyme and yeast usages. Ethanol concentration (at 72 hr) of the enzymatic process was 15.5% (v/v), which was 9.2% higher than the conventional process (14.2% v/v). Distillers dried grains with solubles (DDGS) generated from the enzymatic process (9.8% db) was 66% less than conventional process (28.3% db). Three additional coproducts, germ 8.0% (db), pericarp fiber 7.7% (db) and endosperm fiber 5.2% (db) were produced. Costs and amounts of GSHE used is an important factor affecting dry grind process economics. Proteases can weaken protein matrix to aid starch release and may reduce GSHE doses. Proteases also can hydrolyze protein into free amino nitrogen (FAN), which can be used as a yeast nutrient during fermentation. Two types of proteases, exoprotease and endoprotease, were studied; protease and urea

  17. Nematocyst discharge in Pelagia noctiluca (Cnidaria, Scyphozoa) oral arms can be affected by lidocaine, ethanol, ammonia and acetic acid. (United States)

    Morabito, Rossana; Marino, Angela; Dossena, Silvia; La Spada, Giuseppa


    Nematocyst discharge and concomitant delivery of toxins is triggered to perform both defence and predation strategies in Cnidarians, and may lead to serious local and systemic reactions in humans. Pelagia noctiluca (Cnidaria, Scyphozoa) is a jellyfish particularly abundant in the Strait of Messina (Italy). After accidental contact with this jellyfish, not discharged nematocysts or even fragments of tentacles or oral arms may tightly adhere to the human skin and, following discharge, severely increase pain and the other adverse consequences of the sting. The aim of the present study is to verify if the local anesthetic lidocaine and other compounds, like alcohols, acetic acid and ammonia, known to provide pain relief after jellyfish stings, may also affect in situ discharge of nematocysts. Discharge was induced by a