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ABSTRACT: A polytetrafluoroethylene (PTFE) membrane was used in membrane-assisted extractive (MAE) fermentation of acetone-butanol-ethanol (ABE) by Clostridium saccharoperbutylacetonicum N1-4. The growth inhibition effects of 1-dodecanol, which has a high partition coefficient for butanol, can be prevented by employing 1-dodecanol as an extractant when using a PTFE membrane. Compared to conventional fermentation, MAE-ABE fermentation with 1-dodecanol decreased butanol inhibition and increased glucose consumption from 59.4 to 86.0 g/L, and total butanol production increased from 16.0 to 20.1g/L. The maximum butanol production rate increased from 0.817 to 0.979 g/L/h. The butanol productivity per membrane area was remarkably high with this system, i.e., 78.6g/L/h/m(2). Therefore, it is expected that this MAE fermentation system can achieve footprint downsizing.
Bioresource technology 04/2012; 116:448-52. · 4.25 Impact Factor
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ABSTRACT: BACKGROUND: To use butanol as a liquid fuel and feedstock, it is necessary to establish processes for refining low-concentration butanol solutions. Pervaporation (PV) employing hydrophobic silicalite membranes for selective recovery of butanol is a promising approach. In this study, the adsorption behavior of components present in clostridia fermentation broths on membrane material (silicalite powder) was investigated. The potential of PV using silicone rubber-coated silicalite membranes for the selective separation of butanol from model acetone–butanol–ethanol (ABE) solutions was investigated.RESULTS: The equilibrium adsorbed amounts of ABE per gram of silicalite from aqueous solutions of binary mixtures at 30 °C increased as follows: ethanol (95 mg) < acetone (100 mg) < n-butanol (120 mg). The amount of butanol adsorbed is decreased by the adsorption of acetone and butyric acid. In the separation of ternary butanol/water/acetone mixtures, the enrichment factor for acetone decreased, compared with that in binary acetone/water mixtures. In the separation of a model acetone–butanol–ethanol (ABE) fermentation broth containing butyric acid by PV using a silicone rubber-coated silicalite membrane, the permeate butanol concentration was comparable with that obtained in the separation of a model ABE broth without butyric acid. The total flux decreased with decreasing feed solution pH.CONCLUSION: A silicone rubber-coated silicalite membrane exhibited highly selective PV performance in the separation of a model ABE solution. It is very important to demonstrate the effectiveness of PV in the separation of actual clostridia fermentation broths, and to identify the factors affecting PV performance. Copyright © 2011 Society of Chemical Industry
Journal of Chemical Technology & Biotechnology 03/2011; 86(6):845 - 851. · 2.17 Impact Factor
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ABSTRACT: BACKGROUND: Pervaporation employing ethanol-permselective silicalite membranes as an alternative to distillation is a promising approach for refining low-concentration bioethanol solutions. However, to make the separation process practicable, it is extremely important to avoid the problems caused by the adsorption of succinate on the membrane during the separation process. In this work, the pervaporation of an ethanol fermentation broth without succinate was investigated, as well as the influence of several fermentation broth nutrient components.RESULTS:Candida krusei IA-1 produces an extremely low level of succinate. The decrease in permeate ethanol concentration through a silicone rubber-coated silicalite membrane during the separation of low-succinate C. krusei IA-1 fermentation broth was significantly improved when compared with that obtained using Saccharomyces cerevisiae broth. By treating the fermentation broth with activated carbon, bioethanol was concentrated as efficiently as with binary mixtures of ethanol/water. The total flux was improved upto 56% of that obtained from the separation of binary mixtures, compared with 43% before the addition of activated carbon. Nutrients such as peptone, yeast extract and corn steep liquor had a negative effect on pervaporation, but this response was distinct from that caused by succinate.CONCLUSION: For consistent separation of bioethanol from C. krusei IA-1 fermentation broth by pervaporation, it is useful to treat the low nutrient broth with activated carbon. To further improve pervaporation performance, it will be necessary to suppress the accumulation of glycerol. Copyright © 2009 Society of Chemical Industry
Journal of Chemical Technology & Biotechnology 03/2009; 84(8):1172 - 1177. · 2.17 Impact Factor
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ABSTRACT: The development of fermentative yeasts secreting no organic acids is highly desirable for ethanol production coupled with membrane separation processes, because the acidic byproduct, succinic acid, significantly inhibits the membrane permeation of ethanol. Of the Pichia and Candida yeasts tested, Candida krusei IA-1 showed the highest ethanol productivity [55 g L(-1) day(-1) from 150 g L(-1) (w/v) of glucose], comparable to the strains of Saccharomyces cerevisiae, and produced much less of the acid (0.6 g L(-1) day(-1)) than the Saccharomyces strains (1.5-1.8 g L(-1) day(-1)) under semi-aerobic conditions. Interestingly, under aerobic conditions, strain IA-1 showed no production of the acid. Stain IA-1 exhibited a good assimilation of the acid, while S. cerevisiae NBRC 0216 showed no assimilation. The activity of succinate dehydrogenase (SDH) in strain IA-1 was 37.5 mU mg(-1), and 7.8-fold higher than that in S. cerevisiae strain NBRC 0216. More significantly, SDH1 was abundantly transcribed in strain IA-1, different from that in strain NBRC 0216, regardless of the culture conditions. From these results, C. krusei IA-1 efficiently takes up succinic acid and metabolizes it in the Krebs cycle, producing an extremely low level of byproducts in the culture medium. Therefore, C. krusei is not only a promising alternative to S. cerevisiae but also a suitable model for metabolic engineering of S. cerevisiae.
FEMS Yeast Research 05/2008; 8(5):706-14. · 2.40 Impact Factor
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ABSTRACT: Since pervaporation performance of ethanol-permselective silicalite membrane, which is an aluminum-free hydrophobic zeolite, in the separation of fermentation broths by yeast are negatively affected by succinic acid, the potential of pervaporation using silicone rubber-coated silicalite membranes of ethanol fermentation broths, not containing succinic acid, by Zymomonas mobilis was investigated for the reliable production of concentrated bioethanol. In the separation of fermentation broths, the pervaporation performance was influenced by nutrients used for the preparation of fermentation broths. In the separation of a broth prepared with yeast extract, pervaporation performance was greatly compromised by accumulation of a substance(s) having an ultraviolet absorption maximum at approximately 260 nm not only in total flux, but also in permeate ethanol concentration compared to the separation of binary ethanol/water mixtures. When supplying a prepared broth with corn steep liquor without the accumulation of a substance(s) having an ultraviolet absorption maximum at approximately 260 nm, the permeate ethanol concentration did not decrease. Treating the prepared broth with activated carbon was effective in restraining the decrease in total flux. Pervaporation performance is also deteriorated by the adsorption of lactic acid contained in corn steep liquor onto the silicalite crystals. In the separation of ternary mixtures of ethanol/water/lactic acid, accomplished by adjusting the ternary mixtures to pH > 5, more than 90% of the permeation flux in the separation of binary ethanol/water mixtures was obtained, and the permeate ethanol concentration was comparable to that obtained in the separation of binary mixtures. For stably performing pervaporation, it is important to prepare ethanol fermentation broths by Zymomonas mobilis in which lactic acid concentration is as low as possible. Copyright © 2007 Society of Chemical Industry
Journal of Chemical Technology & Biotechnology 07/2007; 82(8):745 - 751. · 2.17 Impact Factor
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ABSTRACT: Preparation of tubular silicalite membranes by hydrothermal synthesis with electrophoretic deposition (EPD) as a seeding technique was investigated. Two micrometers of small silicalite seeds were produced by an open-system hydrothermal synthesis at 100°C. These seeds were dispersed in 1-propanol and seeded on porous tubular stainless-steel supports by EPD; it had a high productivity and uniformity. The seeded support was then hydrothermally treated, and a tubular silicalite membrane was obtained. The pervaporation performance of this membrane showed a separation factor α of 70 with a total flux of 0.35 kg·(m2·h)−1 for a 5 vol% EtOH aqueous solution at 30°C.
Journal of the American Ceramic Society 09/2005; 89(1):124 - 130. · 2.27 Impact Factor
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Toru Ikegami,
Hideyuki Negishi,
Dai Kitamoto,
Keiji Sakaki,
Tomohiro Imura,
Masayoshi Okamoto,
Yasushi Idemoto,
Nobuyuki Koura,
Tsuneji Sano,
Kenji Haraya,
Hiroshi Yanagishita
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ABSTRACT: In order to produce highly concentrated bioethanol by pervaporation using an ethanol-permselective silicalite membrane, techniques to suppress adsorption of succinic acid, which is a chief by-product of ethanol fermentation and causes the deterioration in pervaporation performance, onto the silicalite crystals was investigated. The amount adsorbed increased as the pH of the aqueous succinic acid solution decreased. The pervaporation performance also decreased with decreasing pH when the ternary mixtures of ethanol/water/succinic acid were separated. Using silicalite membranes individually coated with two types of silicone rubber, pervaporation performance was significantly improved in the pH range of 5 to 7, when compared with that of non-coated silicalite membranes in ternary mixtures of ethanol/water/succinic acid. Moreover, when using a silicalite membrane double-coated with the two types of silicone rubber, pervaporation performance was stabilized at lower pH values. In the separation of bioethanol by pervaporation using the double-coated silicalite membrane, removal of accumulated substances having an ultraviolet absorption maximum at approximately 260 nm from the fermentation broth proved to be vital for efficient pervaporation. Copyright © 2005 Society of Chemical Industry
Journal of Chemical Technology & Biotechnology 03/2005; 80(4):381 - 387. · 2.17 Impact Factor
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ABSTRACT: For the production of highly concentrated bioethanol by pervaporation using an ethanol-permselective silicalite membrane, pervaporation performance was investigated using a silicalite membrane entirely covered with a silicone rubber sheet to prevent direct contact with acidic compounds. By using a resistance model for membrane permeation, the separation factor of the covered silicalite membrane towards ethanol can be estimated from the individual pervaporation performances of the silicalite membrane and the silicone rubber sheet. No decrease in the ethanol concentration through the silicone rubber sheet-covered membrane was caused when ethanol solutions containing succinic acid were supplied. By directly passing the permeate-enriched ethanol vapor mixed with water vapor through a dehydration column packed with a molecular sieve of pore size 0.3 nm, highly concentrated bioethanol up to 97% (w/w), greater than the azeotropic point in the ethanol/water binary systems, can be obtained from 9% (w/w) fermentation broth. Copyright © 2004 Society of Chemical Industry
Journal of Chemical Technology & Biotechnology 06/2004; 79(8):896 - 901. · 2.17 Impact Factor
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ABSTRACT: A coupled fermentation/pervaporation process for reliable production of concentrated ethanol was studied using ethanol permselective silicalite membranes coated with two types of silicone rubber, KE-45 and KE-108, as a hydrophobic material. Ethanol recovery was greatly improved by using a membrane coated with KE-45 silicone rubber. The recovered ethanol concentration in the permeate was 67% (w/w), and the amount of recovered ethanol from the broth was more than 10 times higher than that using a non-coated membrane. Succinic acid and glycerol, by-products created during fermentation, interfered with the pervaporation performance of the coated membrane when used to separate an ethanol/water solution. Copyright © 2003 Society of Chemical Industry
Journal of Chemical Technology & Biotechnology 07/2003; 78(9):1006 - 1010. · 2.17 Impact Factor
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ABSTRACT: Three mannosylerythritol lipids (MEL-A, -B, and -C), yeast glycolipid biosurfactants, were independently attached to poly (2-hydroxyethyl methacrylate) beads (PHEMA), and the three obtained MEL-PHEMA composites were examined for their binding affinity to human immunoglobulin G (HIgG). Of the three composites, the composite bearing MEL-A exhibited the highest binding capacity for HIgG. The binding amount of HIgG increased with increased applied concentration, reaching 106 mg HIgG (per g of composite), with a binding yield of 81%. Interestingly, the protein binding to the composite appeared to follow two different modes (Langmuir type and Freundlich type) depending on the applied concentration. The binding amount of human serum albumin to the composite was much smaller than that of HIgG. The bound human serum albumin, however, had minimal effect on the subsequent binding of HIgG, indicating that the two proteins have different binding sites onto the composite. More significantly, the bound HIgG was efficiently recovered under significantly mild elution conditions: Approximately 90% of the protein was eluted from the composite with phosphate buffer at pH 7. These results indicate that the glycolipid biosurfactant may have great potential as an affinity ligand material for HIgG.
Journal of Biomedical Materials Research Part A 07/2003; 65(3):379-85. · 2.63 Impact Factor
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ABSTRACT: n-Alkanes ranging from C12 to C18 were converted into glycolipid biosurfactants, mannosylerythritol lipids (MEL), by resting cells of Pseudozyma (Candida) antarctica T-34. The highest yield (0.87 g g–1 substrate) was obtained from 6% (v/v) of n-octadecane after 7 days reaction. The amount of MEL reached 140 g l–1 by intermittent feeding of the substrate.
Biotechnology Letters 01/2001; 23(20):1709-1714. · 1.68 Impact Factor
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ABSTRACT: Pervaporation performance using silicalite membranes in the separation of an ethanol/water solution was affected by the addition of sugars, sugar alcohols or yeast cells. Although the membrane flux drastically decreased to about 30% of that for an aqueous ethanol solution with increasing glucose or lactose concentration, the selectivity towards ethanol was inversely enhanced by the addition of glucose from 23 to 137. The accumulated proteins and acidic by-products in the fermentation broth caused the decline in the performance.
Biotechnology Letters 11/1999; 21(12):1037-1041. · 1.68 Impact Factor
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ABSTRACT: Pervaporation dehydration was applied to the lipase-catalyzed esterification of fructose/glucose with palmitic acid in 2-methyl-2-butanol with the intention of improving the reaction yield. The water content in the reaction mixture decreased to 0.03 wt% by means of pervaporation using a zeolite NaA membrane. With the aid of pervaporation dehydration, the total yield of fructose monopalmitate and dipalmitate reached 66% in the esterification started with 54 mM fructose and 108 mM palmitic acid. It was possible to decrease the ratio of diester in the reaction product by decreasing the ratio of fatty acid to sugar in the substrate solution.
Desalination.
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ABSTRACT: In order to stabilize the production of highly concentrated ethanol, a coupled fermentation/pervaporation process using ethanol permselective silicalite membranes coated with silicone rubber was studied. In case of the silicalite membrane without coating, the membrane flux and the ethanol concentration in the permeate decreased with the fermentation time. The completely recovered ethanol fermentation was 30% (w/w). This behavior partly resulted from the adsorption of succinic acid produced during the fermentation to the membrane. It was effective to coat a naked silicalite membrane with the silicone rubber in the production of concentrated fermented ethanol of constant concentration by pervaporation. During the fermentation, the ethanol concentration in the permeate was almost constant, about 70% (w/w) when the silicalite membrane coated with the silicone rubber was used. Even in the case of the fermentation/pervaporation using the coated silicalite membrane, the flux greatly decreased. It is suggested that the glycerol produced during the fermentation, which is not adsorbed by the membranes, might have affected the pervaporation fluxes.
Desalination.
