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  • 1. Abbaszadeh, A
    et al.
    Taherzadeh, Mohammad J.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Effect of extraction conditions on yield and purity of citrus pectin by sulfuric and hydrochloric acids2009Konferansepaper (Fagfellevurdert)
  • 2. Abedinifar, Sorahi
    et al.
    Karimi, Keikhosro
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Khanahmadi, Morteza
    Taherzadeh, Mohammad J.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Ethanol production by Mucor indicus and Rhizapus oryzae from rice straw by separate hydrolysis and fermentation2009Inngår i: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 33, nr 5, s. 828-833Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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 degrees C and pH 5.0. The pretreatment of the straw with dilute-acid hydrolysis resulted in 0.72 g g (1) sugar yield during 48 h enzymatic hydrolysis, which was higher than steam-pretreated (0.60 g g (1)) and untreated straw (0.46 g g(-1)). Furthermore, increasing the concentration of the dilute-acid pretreated straw from 20 to 50 and 100 g L-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(-1) ethanol, 0.11-0.17 g g(-1) biomass, and 0.04-0.06 g g(-1) glycerol, which is comparable with the corresponding yields by S. cerevisiae (0.37-0.45 g g(-1) ethanol, 0.04-0.10 g g(-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(-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(-1), respectively. Crown Copyright (C) 2009 Published by Elsevier Ltd. All rights reserved.

  • 3.
    Ahlström, Peter
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Gebäck, Tobias
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Johansson, Erik
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Bolton, Kim
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Water absorption in polymers2010Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    In this work two different examples of water absorbtion in polymers are studied by Monte Carlo simulations. Both of them are of large technical and commercial impotance. The first example is the water absorption in polyethylene cables where the water absorption plays a crucial role in the degradation of the cable insulation and thus should be as low as possible. The second example is bio-based superabsorbents made from denatured protein where water absorption capability is the prime desired property. Methods Gibbs Ensemble Monte Carlo simulations [1] were used to study the hydration of polymers. All simulations are performed with two boxes, one of which is filled with water at the start of the simulation, whereas the other contains polymer molecules and possible ions. The polymer molecules are not allowed to swap boxes whereas the water molecules are allowed to do so thus constituting an osmotic Gibbs ensemble [2]. For the polyethylene a connectivity-altering algorithm was used whereas the protein molecules were simulated using a side-chain regrowth model in addition to traditional Monte Carlo moves. For the polyethylene, the TraPPE [3] force field was used and the protein molecules, the Amber force field [4] was used. Water was modelled using simple point charge models [5]. Electrostatic interactions are treated using Ewald summation methods. The protein molecules were of different amino acid compositions and in different conformations, e.g., β-turns and random coils obtained using the amorphous cell method[6]. Studies were made with different degrees of charging on, e.g., lysine side chains mimicking different ionization states. Results The studies of polyethylene revealed the importance of ions left from the polymerisation catalyst for the absorbtion of water and the concomitant degradation of polyethylene cable insulation. Also the absorption properties of the protein molecules is strongly related to the presence of charged groups and fully charged protein molecules absorb large amounts of water. However, neither native nor denatured protein molecules show superabsorbing properties (i.e. absorbing hundreds of times their own mass) as they show in experimental studies and the reasons for this discrepancy will be discussed. References 1. A.Z. Panagiotopoulos, Mol. Phys. 61, 813 (1987). 2. E. Johansson, K. Bolton, D.N. Theodorou, P. Ahlström, J. Chem. Phys., 126, 224902 (2007). 3. M.G. Martin, and J.I. Siepmann, J. Phys. Chem. B, 103, 4508-4517 (1999). 4. W.D. Cornell, P. Cieplak, C.I. Bayly, I.R. Gould, K.M. Merz Jr, D.M. Ferguson, D.C. Spellmeyer, T. Fox, J.W. Caldwell, P.A. Kollman (1995). J. Am. Chem. Soc. 117, 5179–5197. 5. H. J. C. Berendsen, J. P. M. Postma and W. F. van Gunsteren, in Intermolecular Forces, B. Pullman, ed. (Reidel, Dordrecht, 1981) p. 331; H. J. C. Berendsen, J. R. Grigera and T. P. Straatsma, J. Phys. Chem. 91, 6269 (1987). 6. D.N. Theodorou, U.W. Suter, Macromolecules, 18, 1467 (1985).

  • 4. Beigi, H.M.
    et al.
    Karimi, Keikhosro
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Effects of temperature, pH and glucose concentration on bioethanol production by Mucor indicus2009Konferansepaper (Annet vitenskapelig)
  • 5. Bidgoli, Hossein
    et al.
    Zamani, Akram
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Taherzadeh, Mohammad J.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Effect of carboxymethylation conditions on water binding capacity of chitosan-based superabsorbents2010Inngår i: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 345, nr 18, s. 2683-2689Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A superabsorbent polymer (SAP) from chitosan was provided via carboxymethylation of chitosan, followed by cross-linking with glutaraldehyde and freeze-drying. This work was focused on an investigation of the effects of monochloroacetic acid (MCAA), sodium hydroxide, and reaction time on preparation of carboxymethylchitosan (CMCS). The CMCS products were characterized using FTIR spectroscopy, and their degrees of substitution (DS) were measured using conductimetry and FTIR analysis. The highest DS value was obtained when the carboxymethylation reaction was carried out using 1.75 g MCAA and 1.75 g NaOH per g of chitosan in 4 h. The water solubilities of the CMCS products at various pHs were also evaluated, and the results indicated a significant impact of the reaction parameters on the solubility of CMCS. The CMCSs with the highest DS value resulted in SAPs having the highest water-binding capacity (WBC). TheWBCof the best SAP measured after 10 minexposure in distilled water, 0.9% NaCl solution, synthetic urine, and artificial blood was 104, 33, 30, and 57 g/g, respectively. The WBC of this SAP at pH 2–9 passed a maximum at pH 6.

  • 6.
    Dehkhoda, Anahita
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Brandberg, Tomas
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Taherzadeh, Mohammad J.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Comparison of vacuum and high pressure evaporated wood hydrolyzate for ethanol production by repeated fed-batch using flocculating Saccharomyces cerevisiae2009Inngår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 4, nr 1, s. 309-320Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Comparison of vacuum and high pressure evaporated wood hydrolyzate for ethanol production by repeated fed-batch using flocculating Saccharomyces cerevisiae

  • 7. Ebrahimi, Fatemeh
    et al.
    Khanahmadi, Morteza
    Taherzadeh, Mohammad J.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Ethanol production from bread residues2008Inngår i: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 32, nr 4, s. 333-337Artikkel i tidsskrift (Fagfellevurdert)
  • 8.
    Erdtman, Edvin
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Gebäck, Tobias
    Ahlström, Peter
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Computational modeling of Protein based super-absorbents from waste2011Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Hydrogels are used for various applications, for example as transporters in drug delivery, in control lenses, and as superabsorbent material in diapers.[1] Most synthetic produced hydrogels are based on synthetic polymers. Even though they are efficient and cheap, they are not biodegradable and sometimes even toxic. To produce more environmental friendly and biodegradable superabsorbent polymers (Bio- SAPs), other building blocks can be used, such as polysaccharides[2] and various protein structures, for example fish shells[3], collagen[4], soy protein[5] and egg protein[6]. Experimental studies at the University of Boras show that it is possible to produce Bio-SAPs from by-products of ethanol production from ligno-cellulose.[2, 6, 7] 2. Method We have studied the absorption properties of protein structures in silico as a comparison to experimental studies. The NPT Gibbs Ensemble Monte Carlo (GEMC) simulation scheme with two phases is used in order to calculate the absorption capacity of the protein. Pure water was simulated in the first GEMC-phase and the peptide in the second phase. The simulations were made with SPC/E water model [8] and the AMBER99 atomistic force field for the peptides [9]. Furthermore, mesoscopic studies with coarse grained force fields have been done. To facilitate faster computations, we used cell lists for the atom-atom interactions, configurational bias algorithm to build the water molecules and the peptide side-chains, and the cavity bias algorithm [10] for molecule insertions. Model peptides have been studied with varying secondary structure, temperature and protonation (pH). We also plan to study how cross-links affect the absorption. One of the peptides we study is a 20 amino acid long peptide called SSP1.[11] This peptide is designed to form a fibrous structure a hydrogel, and its structure is well defined. We have also studied a peptide which changes secondary structure when changing the pH, and concentration.[12] This makes it possible to compare absorption properties with respect to the secondary structure. 3. Conclusion We have simulated peptides with the Gibbs Ensemble Monte Carlo scheme in order to study the water absorption rate dependent of structure, charge, pH and temperature. This information is useful when developing new biodegradable superabsorbent materials.

  • 9.
    Ishola, Mofoluwake M.
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Brandberg, Tomas
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Taherzadeh, Mohammad
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Evaluation of Nigerian Agricultural Biomass for Bioethanol Production2011Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Nigeria is a tropical country with the over 150 million inhabitants out of which 70% is employed by agriculture. Bioethanol sticks out as the most important renewable biofuel and can be produced from lignocellulosic materials which include agricultural residues. Nigeria has the potentials of becoming a major biofuel ethanol producing country considering huge amount of agricultural wastes and residues generated each year, however, there is need for proper evaluation and planning before heavily investment in commercial production. This study focuses on the evaluation of the potentials of bioethanol production in Nigeria from various agricultural biomass and residues.

  • 10. Jafari, Vahid
    et al.
    Jeihanipour, Azam
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Karimi, Keikhosro
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Taherzadeh, Mohammad
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Conversion of Waste Wallpaper to Ethanol2009Konferansepaper (Annet vitenskapelig)
  • 11.
    Jeihanipour, Azam
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Waste Textiles Bioprocessing to Ethanol and Biogas2011Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    The work of the present thesis focused on conversion of the cellulosic part of waste textiles into biogas and ethanol, and its challenges. In 2009, the global annual fiber consumption exceeded 70 Mt, of which around 40% consisted of cellulosic material. This huge amount of fibers is processed into apparel, home textiles, and industrial products, ending up as waste after a certain time delay. Regretfully, current management of waste textiles mainly comprises incineration and landfilling, in spite of the potential of cellulosic material being used in the production of ethanol or methane. The volume of cellulose mentioned above would be sufficient for producing around 20 billion liters of ethanol or 11.6 billion Nm3 of methane per year. Nevertheless, waste textiles are not yet accepted as a suitable substrate for biofuel production, since their processing to biofuel presents certain challenges, e.g. high crystallinity of cotton cellulose, presence of dyes, reagents and other materials, and being textiles as a mixture of natural and synthetic fibers. High crystallinity of cotton cellulose curbs high efficient conversion by enzymatic or bacterial hydrolysis, and the presence of non-cellulosic fibers may create several processing problems. The work of the present thesis centered on these challenges. Cotton linter and blue jeans waste textiles, all practically pure cellulose, were converted to ethanol by SSSF, using S. cerevisiae, with a yield of about 0.14 g ethanol/g textile, only 25% of the theoretical yield. To improve the yield, a pretreatment process was required and thus, several methods were examined. Alkaline pretreatments significantly improved the yield of hydrolysis and subsequent ethanol production, the most effective condition being treatment with a 12% NaOH-solution at 0 °C, increasing the yield to 0.48 g ethanol/g textile (85% of the theoretical yield). Waste textile streams, however, are mixtures of different fibers, and a separation of the cellulosic fibers from synthetic fibers is thus necessary. The separation was not achieved using an alkaline pretreatment, and hence another approach was investigated, viz. pretreatment with N-methyl-morpholine-N-oxide (NMMO), an industrially available and environment friendly cellulose solvent. The dissolution process was performed under different conditions in terms of solvent concentration, temperature, and duration. Pretreatment with 85% NMMO at 120 °C under atmospheric pressure for 2.5 hours, improved the ethanol yield by 150%, compared to the yield of untreated cellulose. This pretreatment proved to be of major advantage, as it provided a method for dissolving and then recovering the cellulose. Using this method as a foundation, a novel process was developed, refined and verified, by testing polyester/cellulose-blended textiles, which predominate waste textiles. The polyesters were purified as fibers after the NMMO treatments, and up to 95% of the cellulose content was regenerated. The solvent was then recovered, recycled, and reused. Furthermore, investigating the effect of this treatment on anaerobic digestion of cellulose disclosed a remarkable enhancement of the microbial solubilization; the rate in pretreated textiles was twice the rate in untreated material. The overall yield of methane was, however, not significantly affected. The process developed in the present thesis appears promising for transformation of waste textiles into a suitable raw material, to subsequently be used for biological conversion to ethanol and biogas.

  • 12.
    Jeihanipour, Azam
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Karimi, Keikhosro
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Taherzadeh, Mohammad
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Effective pretreatment of high crystalline cellulose by NMMO2009Konferansepaper (Annet vitenskapelig)
  • 13.
    Jeihanipour, Azam
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Taherzadeh, Mohammad
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Enhancement of initial rate of solubilisation in anaerobic digestion of cellulose by NMMO pretreatment2010Konferansepaper (Annet vitenskapelig)
  • 14.
    Jeihanipour, Azam
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Taherzadeh, Mohammad J.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Ethanol production from cotton-based waste textiles2009Inngår i: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 100, nr 2, s. 1007-1010Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ethanol production from cotton linter and waste of blue jeans textiles was investigated. In the best case, alkali pretreatment followed by enzymatic hydrolysis resulted in almost complete conversion of the cotton and jeans to glucose, which was then fermented by Saccharomyces cerevisiae to ethanol. If no pretreatment applied, hydrolyses of the textiles by cellulase and P-glucosidase for 24 h followed by simultaneous saccharification and fermentation (SSF) in 4 days, resulted in 0.140-0.145 g ethanol/g textiles, which was 25-26% of the corresponding theoretical yield. A pretreatment with concentrated phosphoric acid prior to the hydrolysis improved ethanol production from the textiles up to 66% of the theoretical yield. However, the best results obtained from alkali pretreatment of the materials by NaOH. The alkaline pretreatment of cotton fibers were carried out with 0-20% NaOH at 0 degrees C, 23 degrees C and 100 degrees C, followed by enzymatic hydrolysis up to 4 days. In general, higher concentration of NaOH resulted in a better yield of the hydrolysis, whereas temperature had a reverse effect and better results were obtained at lower temperature. The best conditions for the alkali pretreatment of the cotton were obtained in this study at 12% NaOH and 0 degrees C and 3 h. In this condition, the materials with 3% solid content were enzymatically hydrolyzed at 85.1% of the theoretical yield in 24 h and 99.1% in 4 days. The alkali pretreatment of the waste textiles at these conditions and subsequent SSF resulted in 0.48 g ethanol/g pretreated textiles used. (c) 2008 Elsevier Ltd. All rights reserved.

  • 15.
    Jeihanipour, Azam
    et al.
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Zamani, Akram
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Karimi, Keikhosro
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Taherzadeh, Mohammad
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Effect of growing time on the chitosan content of cell wall of zygomycetes fungi2009Konferansepaper (Annet vitenskapelig)
  • 16.
    Kabir, Maryam M.
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Mirahmadi, Kambiz
    Jeihanipour, Azam
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Karimi, Keikhosro
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Taherzadeh, Mohammad
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Effect of sodium hydroxide pretreatment on enzymatic hydrolysis of softwoods and hardwoods2009Konferansepaper (Annet vitenskapelig)
  • 17.
    Karimi, Keikhosro
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Edebo, Lars
    Taherzadeh, Mohammad J.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Mucor indicus as a biofilter and fermenting organism in continuous ethanol production from lignocellulosic hydrolyzate2008Inngår i: Biochemical engineering journal, ISSN 1369-703X, E-ISSN 1873-295X, Vol. 39, nr 2, s. 383-388Artikkel i tidsskrift (Fagfellevurdert)
  • 18.
    Lennartsson, Patrik
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Edebo, Lars
    Taherzadeh, Mohammad J.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Ethanol and valuable byproducts from lignocellulosic materials by zygomycetes2009Konferansepaper (Annet vitenskapelig)
  • 19.
    Lennartsson, Patrik
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Karimi, Keikhosro
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Edebo, Lars
    Taherzadeh, Mohammad
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Effects of different growth forms of Mucor indicus on cultivation on dilute-acid lignocellulosic hydrolyzate, inhibitor tolerance, and cell wall composition2009Inngår i: Journal of Biotechnology, ISSN 0168-1656, E-ISSN 1873-4863, Vol. 143, nr 4, s. 225-261Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The dimorphic fungus Mucor indicus was grown in different forms classified as purely filamentous, mostly filamentous, mostly yeast-like and purely yeast-like, and the relationship between morphology and metabolite production, inhibitor tolerance and the cell wall composition was investigated. Low concentrations of spores in the inoculum with subsequent aeration promoted filamentous growth, whereas higher spore concentrations and anaerobic conditions promoted yeast-like growth. Ethanol was the main metabolite with glycerol next under all conditions tested. The yields of ethanol from glucose were between 0.39 and 0.42 g g−1 with productivities of 3.2–5.0 g l−1 h−1. The ethanol productivity of mostly filamentous cells was increased from 3.9 to 5.0 g l−1 h−1 by the presence of oxygen, whereas aeration of purely yeast-like cells showed no such effect. All growth forms were able to tolerate 4.6 g l−1 furfural and 10 g l−1 acetic acid and assimilate the sugars, although with different consumption rates. The cell wall content of the fungus measured as alkali insoluble materials (AIM) of the purely yeast-like cells was 26% of the biomass, compared to 8% of the pure filaments. However, the chitosan concentration of the filaments was 29% of the AIM, compared to 6% of the yeast-like cells.

  • 20.
    Lennartsson, P.R.
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Karimi, K.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Edebo, L.
    Taherzadeh, M.J.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Ethanol production by dimorphic fungus Mucor indicus2008Konferansepaper (Fagfellevurdert)
  • 21. Majdejabbari, Sara
    et al.
    Barghi, Hamidreza
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Taherzadeh, Mohammad J.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Synthesis and Characterization of Biosuperabsorbent Based on Ovalbumin Protein2010Inngår i: Journal of macromolecular science. Pure and applied chemistry (Print), ISSN 1060-1325, E-ISSN 1520-5738, Vol. 47, nr 7, s. 708-715Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    A biosuperabsorbent (Bio-SAP) hydrogel from ovalbumin (egg protein) was synthesized via modification with an acylating reagent and a bifunctional crosslinker, and its swelling behavior was investigated. The protein was acylated using ethylenediaminetetraacetic dianhydride (EDTAD), and then crosslinked by glutaraldehyde and dried. Bio-SAP provided through this method includes modification of lysyl residues in the unfolded protein by adding one or more hydrophilic carboxyl groups to increase the hydrophilicity of protein. The water binding capacity was measured in deionized water, 0.9% NaCl solution and synthetic urine, which under the best conditions were 296, 64 and 56 g/g after 24 h, respectively. In addition, the effects of EDTAD/protein ratio on the chemical modification of the protein, the various chemical neutralization agents, pH sensitivity and ionic strength, as well as temperature and particle size on the water absorption capacity with and without load and its kinetic were also investigated.

  • 22. Menéndez Ramírez, Zurima
    et al.
    Jeihanipour, Azam
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Zumalacárregui de Cárdenas, Lourdes
    Taherzadeh, Mohammad
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Optimization of enzymes concentration in hydrolysis of alkaline-pretreated cotton-based waste textiles2010Konferansepaper (Annet vitenskapelig)
  • 23. Millati, R.
    et al.
    Karimi, K.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Edebo, L.
    Niklasson, C.
    Taherzadeh, M.J.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Ethanol production from xylose and wood hydrolyzate by Mucor indicus at different aeration rates2008Inngår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 3, nr 4, s. 1020-1029Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The fungus Mucor indicus is able to produce ethanol from xylose as well as dilute-acid lignocellulosic hydrolyzates. The fungus completely assimilated 10 g/L xylose as the sole carbon and energy source within 32 to 65 h at an aeration rate of 0.1 to 1.0 vvm. The highest ethanol yield was 0.16 g/g at 0.1 vvm. Xylitol was formed intermediately with a maximum yield of 0.22 g/g at 0.5 vvm., but disappeared towards the end of experiments. During cultivation in a mixture of xylose and glucose, the fungus did not assimilate xylose as long as glucose was present in the medium. The anaerobic cultivation of the fungus in the hydrolyzate containing 20% xylose and 80% hexoses resulted in no assimilation of xylose but complete consumption of the hexoses in less than 15 h. The ethanol yield was 0.44 g/g. However, the xylose in the hydrolyzate was consumed when the media were aerated at 0.067 to 0.333 vvm. The best ethanol yield was 0.44 g/g at 0.067 vvm. The results of this study suggest that M. indicus hydrolyzate can be first fermented anaerobically for hexose assimilation and subsequently continued under oxygen-limited conditions for xylose fermentation.

  • 24. Millati, Ria
    et al.
    Wikandari, Rachma
    Trihandayani, Elisabeth Titik
    Nur Cahyanto, Muhammad
    Taherzadeh, Mohammad J.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Niklasson, Claes
    Ethanol from Oil Palm Empty Fruit Bunch via Dilute-Acid Hydrolysis and Fermentation by Mucor indicus and Saccharomyces cerevisiae2011Inngår i: Agricultural Journal, ISSN 1994-4616, Vol. 6, nr 2, s. 54-59Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Oil Palm Empty Fruit Bunch (OPEFB) was hydrolyzed in a one-stage hydrolysis using dilute-sulfuric acid (0.2, 0.8%) at 170-230°C with a holding time of 5 and 15 min. The maximum yield of xylose was 135.94 g kg-1 OPEFB, obtained at 0.8% acid, 190°C and 5 min. The maximum yield of glucose was 62.70 g kg-1 OPEFB, obtained at 0.8% acid, 210°C and 5 min. Based on these results, two-stage hydrolysis was performed to produce hydrolyzates for the fermentation process. Hydrolyzate from the first stage was fermented by Mucor indicus while the hydrolyzate from the second stage was fermented by Saccharomyces cerevisiae. The corresponding ethanol yields were 0.45 and 0.46 g ethanol g-1 sugar consumed.

  • 25. Mirabdollah, A.
    et al.
    Alinezhad, S.
    Feuk-Lagerstedt, Elisabeth
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Sárvári Horváth, Ilona
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Optimization of a protoplast transformation method for Bacillus Subtilis, Bacillus megaterium, and Bacillus Cereus by a plasmid pHIS1525.SplipA2009Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    During the past years of gene cloning studies, Escherichia coli has always been a foremost host cell for exogenous genes expressions owing to its high level of protein production and excretion. However, problems relating to low level of extracellular production of some proteins specially the accumulation of cloned proteases within the cells have moved the attentions from E.coli to bacilli bacteria such as B. megaterium, B.subtilis, and B.cereus due to their secretion ability of many different enzymes. Bacillus megaterium is widely used for high-level expression of heterologous proteins with little or no degradation. Bacillus subtilis is a naturally competent host cell for uptake of exogenous DNA, resulting in attractive industrial applications. Bacillus cereus has sporulation capability which makes it suitable for several industrial uses. A conventional approach for transferring DNA into protoplasts or intact cells of bacillus bacteria is chemical transformation, using chemicals through chilling and then shock-heating of the suspension of cells to induce reversible permeabilization of the cell membrane to make it possible for the external DNA to enter into the cells. In most cloning experiments, the transformation with plasmid DNA is performed using Polyethylene glycol (PEG)-induced competence cells. In this study, a PEG-induced protoplast transformation protocol was developed for three different bacillus strains of Bacillus megaterium ATCC®14945, Bacillus Subtilis ATCC®6051, and Bacillus Cereus ATCC®14579. In all cases a plasmid pHIS1525.SPlipA, well working vector in B.megaterium, was applied. Protoplasts were formed in RHAF medium after treating the cells with lysozyme. Two factors, the incubation time and the lysozyme concentration have been found to play the most important role in effective protoplast formation. These two factors were further optimized in this study to elaborate a chemical transformation procedure which can possibly work for other bacillus strains as well. The optical density (A420) and the number of colony-forming units (CFUs) were determined to find the optimal conditions for each strain. The results indicate that PEG-induced protoplast transformation is a sufficient technique when using a plasmid pHIS1525.SPlipA in Bacillus genus.

  • 26. Mirahmadi, Kambiz
    et al.
    Mohseni Kabir, Maryam
    Jeihanipour, Azam
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Karimi, Keikhosro
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Taherzadeh, Mohammad
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Optimization of sodium hydroxide pretreatment for enzymatic hydrolysis of lignocellulosic materials2009Konferansepaper (Annet vitenskapelig)
  • 27. Mohsenzadeh Syouki, Abas
    et al.
    Jeihanipour, Azam
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Karimi, Keikhosro
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Taherzadeh, Mohammad
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Enhancement of enzymatic hydrolysis of wood by pretreatment with different cellulose dissolution systems2009Konferansepaper (Annet vitenskapelig)
  • 28.
    Pourbafrani, Mohammad
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Citrus Waste Biorefinery: Process Development, Simulation and Economic Analysis2010Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    The production of ethanol and other sustainable products including methane, limonene and pectin from citrus wastes (CWs) was studied in the present thesis. In the first part of the work, the CWs were hydrolyzed using enzymes – pectinase, cellulase and β-glucosidase – and the hydrolyzate was fermented using encapsulated yeasts in the presence of the inhibitor compound ‘limonene’. However, the application of encapsulated cells may be hampered by the high price of encapsulation, enzymes and the low stability of capsules’ membrane at high shear stresses. Therefore, a process based on dilute-acid hydrolysis of CWs was developed. The limonene of the CWs was effectively removed through flashing of the hydrolyzate into an expansion tank. The sugars present in the hydrolyzate were converted to ethanol using a flocculating yeast strain. Then ethanol was distilled and the stillage and the remaining solid materials of the hydrolyzed CWs were anaerobically digested to obtain methane. The soluble pectin content of hydrolyzate can be precipitated using the produced ethanol. One ton of CWs with 20% dry weight resulted in 39.64 l ethanol, 45 m3 methane, 8.9 l limonene, and 38.8 kg pectin. The feasibility of the process depends on the transportation cost and the capacity of CW. For example, the total cost of ethanol with a capacity of 100,000 tons CW/year was 0.91 USD/L, assuming 10 USD/ton handling and transportation cost of CW to the plant. Changing the plant capacity from 25,000 to 400,000 tons CW per year results in reducing ethanol costs from 2.55 to 0.46 USD/L in an economically feasible process. Since this process employs a flocculating yeast strain, the major concern in design of the bioreactor is the sedimentation of yeast flocs. The size of flocs is a function of sugar concentration, time and flow. A CFD model of bioreactor was developed to predict the sedimentation of flocs and the effect of flow on distribution of flocs. The CFD model predicted that the flocs sediment when they are larger than 180 micrometer. The developed CFD model can be used in design and scale-up of the bioreactor. For the plants with low CW capacity, a steam explosion process was employed to eliminate limonene and the treated CW was used in a digestion plant to produce methane. The required cost of this pretreatment was about 0.90 million dollars for 10,000 tons/year of CWs.

  • 29.
    Pourbafrani, Mohammad
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Taherzadeh, Mohammad
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Ethanol from Softwood: Process Simulation and Energy Analysis2009Konferansepaper (Annet vitenskapelig)
  • 30.
    Pourbafrani, Mohammad
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Talebnia, Farid
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Taherzadeh, Mohammad
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Production of Bioethanol from Citrus Wastes by Encapsulated Yeast2009Inngår i: Proceeding ISWA/APESB 2009 World Congress, Lissabon, Proceeding ISWA/APESB 2009 World Congress , 2009Konferansepaper (Fagfellevurdert)
  • 31.
    Purwadi, Ronny
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Taherzadeh, Mohammad J.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    The performance of serial bioreactors in rapid continuous production of ethanol from dilute-acid hydrolyzates using immobilized cells2008Inngår i: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 99, nr 7, s. 2226-2233Artikkel i tidsskrift (Fagfellevurdert)
  • 32. Rahim Labafzadeh, Sara
    et al.
    Jafari, Vahid
    Jeihanipour, Azam
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Karimi, Keikhosro
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Taherzadeh, Mohammad
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Conversion of Prevalent Building Waste to Ethanol2009Konferansepaper (Annet vitenskapelig)
  • 33. Samiei, K.
    et al.
    Fröling, M.
    Taherzadeh, M.J.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Optimal use of biomass resources in a biorefinery type setting: Case study of a bioethanol concept2008Konferansepaper (Fagfellevurdert)
  • 34.
    Satari, B.
    et al.
    Swedish Centre for Resource Recovery, University of Borås.
    Karimi, K.
    Department of Chemical Engineering, Isfahan University of Technology.
    Taherzadeh, Mohammad J
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Zamani, Akram
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Co-production of fungal biomass derived constituents and ethanol from citruswastes free sugars without auxiliary nutrients in airlift bioreactor2016Inngår i: International Journal of Molecular Sciences, ISSN 1422-0067, E-ISSN 1422-0067, Vol. 17, nr 3Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The potential of two zygomycetes fungi, Mucor indicus and Rhizopus oryzae, in assimilating citrus waste free sugars (CWFS) and producing fungal chitosan, oil, and protein as well as ethanol was investigated. Extraction of free sugars from citrus waste can reduce its environmental impact by decreasing the possibility of wild microorganisms growth and formation of bad odors, a typical problem facing the citrus industries. A total sugar concentration of 25.1 g/L was obtained by water extraction of citrus waste at room temperature, used for fungal cultivation in shake flasks and airlift bioreactor with no additional nutrients. In shake flasks cultivations, the fungi were only able to assimilate glucose, while fructose remained almost intact. In contrast, the cultivation of M. indicus and R. oryzae in the four-liter airlift bioreactor resulted in the consumption of almost all sugars and production of 250 and 280 g fungal biomass per kg of consumed sugar, respectively. These biomasses correspondingly contained 40% and 51% protein and 9.8% and 4.4% oil. Furthermore, the fungal cell walls, obtained after removing the alkali soluble fraction of the fungi, contained 0.61 and 0.69 g chitin and chitosan per g of cell wall for M. indicus and R. oryzae, respectively. Moreover, the maximum ethanol yield of 36% and 18% was obtained from M. indicus and R. oryzae, respectively. Furthermore, that M. indicus grew as clump mycelia in the airlift bioreactor, while R. oryzae formed spherical suspended pellets, is a promising feature towards industrialization of the process. 

  • 35. Shafiei, M
    et al.
    Karimi, Keikhosro
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Taherzadeh, Mohammad
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Ethanol production by flocculating Saccharomyces cerevisiae2009Konferansepaper (Annet vitenskapelig)
  • 36. Shafiei, Marzieh
    et al.
    Karimi, Keikhosro
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Taherzadeh, Mohammad J.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Palm Date Fibers: Analysis and Enzymatic Hydrolysis2010Inngår i: International Journal of Molecular Sciences, ISSN 1422-0067, E-ISSN 1422-0067, Vol. 11, nr 11, s. 4285-4296Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Waste palm dates were subjected to analysis for composition and enzymatic hydrolysis of their flesh fibers. The fruit contained 32% glucose and 30% fructose, while the water-insoluble fibers of its flesh consisted of 49.9% lignin and 20.9% polysaccharides. Water-insoluble fibers were settled to 55% of its initial volume in 12 h. The presence of skin and flesh colloidal fibers results in high viscosity and clogging problems during industrial processes. The settling velocity of the fibers was improved by enzymatic hydrolysis. Hydrolysis resulted in 84.3% conversion of the cellulosic part of the fibers as well as reducing the settling time to 10 minutes and the final settled volume to 4% of the initial volume. It implies easier separation of the fibers and facilitates fermentation processes in the corresponding industries. Two kinds of high- and low-lignin fibers were identified from the water-insoluble fibers. The high-lignin fibers (75% lignin) settled easily, while the low-lignin fibers (41.4% lignin) formed a slurry suspension which settled very slowly. The hydrophilicity of these low-lignin fibers is the major challenge of the industrial processes.

  • 37.
    Sharifia, Mahnaz
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Karimi, Keikhosro
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Taherzadeh, Mohammad J
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Production of ethanol by filamentous and yeast-like forms of Mucor indicus from fructose, glucose, sucrose and molasses2008Inngår i: Journal of Industrial Microbiology & Biotechnology, ISSN 1367-5435, E-ISSN 1476-5535, Vol. 35, nr 11, s. 1253-1259Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The fungus Mucor indicus is found in this study able to consume glucose and fructose, but not sucrose in fermentation of sugarcane and sugar beet molasses. This might be an advantage in industries which want to selectively remove glucose and fructose for crystallisation of sucrose present in the molasses. On the other hand, the fungus assimilated sucrose after hydrolysis by the enzyme invertase. The fungus efficiently grew on glucose and fructose and produced ethanol in synthetic media or from molasses. The cultivations were carried out aerobically and anaerobically, and manipulated toward filamentous or yeast-like morphology. Ethanol was the major metabolite in all the experiments. The ethanol yield in anaerobic cultivations was between 0.35 and 0.48 g/g sugars consumed, depending on the carbon source and the growth morphology, while a yield of as low as 0.16 g/g was obtained during aerobic cultivation. The yeast-like form of the fungus showed faster ethanol production with an average productivity of 0.90 g/l h from glucose, fructose and inverted sucrose, than the filamentous form with an average productivity of 0.33 g/l h. The biomass of the fungus was also analyzed with respect to alkali-insoluble material (AIM), chitin, and chitosan. The biomass of the fungus contained per g maximum 0.217 g AIM and 0.042 g chitosan in yeast-like cultivation under aerobic conditions.

  • 38. Soudham, Venkata Prabhakar
    et al.
    Rodriguez, Dani
    Rocha, George J M
    Taherzadeh, Mohammad J.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Martin, Carlos
    Acetosolv delignifi cation of marabou (Dichrostachys cinerea) wood with and without acid prehydrolysis2011Inngår i: Forestry Studies in China, ISSN 1008-1321, Vol. 13, nr 1, s. 64-70Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The chemical composition of marabou (Dichrostachys cinerea) wood and its treatment with acetic acid were investigated. Two different treatment approaches, direct acetosolv and combined acid prehydrolysis/acetosolv, were evaluated. The effects of acetic acid concentration (50%, 70% and 90%) and temperature (normal boiling temperature and 121°C) on yield of solids, solubilization of lignin and hemicelluloses and recovery of cellulose were evaluated for both treatments. High solubilization of marabou components was observed in the direct acetosolv treatment at 121°C, especially at the highest acetic acid concentration, where around 84.8% of lignin and 78% of hemicelluloses were removed. When the material was subjected to acid prehydrolysis prior to acetosolv treatment, lignin solubilization was improved, especially at low acetic acid concentrations. Above 80% of the solubilized lignin was recovered from the liquors in the direct acetosolv treatment, but the recovery was lower in the combined treatment. Cellulose was well preserved in all the treatment schemes.

  • 39.
    Souza Filho, Pedro
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Fungi-based biorefinery model for food industry waste: progress toward a circular economy2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The food industry, one of the most important industrial sectors worldwide, generates large amounts of biodegradable waste with high organic load. In recent years, the traditional management methods to treat this waste (e.g., landfilling) have been considered not suitable because they do not exploit the potential of the waste material. Alternatively, valorization of food industry waste via a biorefinery model using filamentous fungi is considered to represent an attractive strategy because it minimizes the negative impacts while recovering the nutrients and energy of the waste, in accordance with the concept of the circular economy.

    In this thesis, four food processing wastes were utilized as case studies: potato protein liquor (PPL, the soluble fraction of potato starch production waste), the peels wasted during orange juice production, the starchy byproduct of pea protein processes, and the wastewater of a wheat-starch plant. Rhizopus oryzae, a zygomycetous filamentous fungus, was grown with these wastes as a substrate, yielding biomass containing 43% (w/w) protein together with 51% removal of the chemical oxygen demand when cultivated in tenfold-diluted PPL. Moreover, protein-rich biomass was produced using the pea-processing byproduct (55%) and wheat-starch wastewater (51%). In contrast, cultivation in orange peel extract yielded a biomass rich in lipids (20%). The use of PPL was also studied in terms of the economy of fungal cultivation. The biotreatment was found to require only 46% of the capital investment necessary for treating PPL by the traditional strategy (application as fertilizer). In comparison, the ascomycetous fungus Aspergillus oryzae yielded superior results compared to those of R. oryzae when grown in the starchy residues. The high protein content of the fungal biomass encouraged the investigation of its use for bioplastic production. The addition of 20% fungal biomass in a pectin matrix increased the tensile yield of the film and reduced the elongation at break. Moreover, a positive effect on water vapor permeability of the film was also observed.

    These results indicate the ability of the filamentous fungi to convert resources wasted by the food industry into new products with positive impacts on the economy and the environment.

  • 40.
    Souza Filho, Pedro Ferreira
    et al.
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Zamani, Akram
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Taherzadeh, Mohammad J
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Edible Protein Production by Filamentous Fungi using Starch Plant Wastewater2018Inngår i: Waste and Biomass Valorization, ISSN 1877-2641, s. 1-10Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The process to obtain starch from wheat requires high amounts of water, consequently generating large amounts of wastewater with very high environmental loading. This wastewater is traditionally sent to treatment facilities. This paper introduces an alternative method, where the wastewater of a wheat-starch plant is treated by edible filamentous fungi (Aspergillus oryzae and Rhizopus oryzae) to obtain a protein-rich biomass to be used as e.g. animal feed. The wastewater was taken from the clarified liquid of the first and second decanter (ED1 and ED2, respectively) and from the solid-rich stream (SS), whose carbohydrate and nitrogen concentrations ranged between 15 and 90 and 1.25–1.40 g/L, respectively. A. oryzae showed better performance than R. oryzae, removing more than 80% of COD after 3 days for ED1 and ED2 streams. Additionally, 12 g/L of dry biomass with protein content close to 35% (w/w) was collected, demonstrating the potential of filamentous fungi to be used in wastewater valorization. High content of fermentable solids in the SS sample led to high production of ethanol (10.91 g/L), which can be recovered and contribute to the economics of the process.

  • 41.
    Souza Filho, Pedro
    et al.
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Nair, Ramkumar
    Mycorena AB.
    Andersson, Dan
    Högskolan i Borås, Akademin för vård, arbetsliv och välfärd.
    Lennartsson, Patrik R.
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Taherzadeh, Mohammad J
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Vegan-mycoprotein concentrate from pea-processing industry byproduct using edible filamentous fungi2018Inngår i: Fungal Biology and Biotechnology, ISSN 2054-3085, Vol. 5, nr 5Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background

    Currently around one billion people in the world do not have access to a diet which provides enough protein and energy. However, the production of one of the main sources of protein, animal meat, causes severe impacts on the environment. The present study investigates the production of a vegan-mycoprotein concentrate from pea-industry byproduct (PpB), using edible filamentous fungi, with potential application in human nutrition. Edible fungal strains of Ascomycota (Aspergillus oryzaeFusarium venenatumMonascus purpureusNeurospora intermedia) and Zygomycota (Rhizopus oryzae) phyla were screened and selected for their protein production yield.

    Results

    A. oryzae had the best performance among the tested fungi, with a protein yield of 0.26 g per g of pea-processing byproduct from the bench scale airlift bioreactor cultivation. It is estimated that by integrating the novel fungal process at an existing pea-processing industry, about 680 kg of fungal biomass attributing to about 38% of extra protein could be produced for each 1 metric ton of pea-processing byproduct. This study is the first of its kind to demonstrate the potential of the pea-processing byproduct to be used by filamentous fungi to produce vegan-mycoprotein for human food applications.

    Conclusion

    The pea-processing byproduct (PpB) was proved to be an efficient medium for the growth of filamentous fungi to produce a vegan-protein concentrate. Moreover, an industrial scenario for the production of vegan-mycoprotein concentrate for human nutrition is proposed as an integrated process to the existing PPI production facilities.

  • 42.
    Taherzadeh, M.J.
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Karimi, K.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Pretreatment of lignocellulosic wastes to improve ethanol and biogas production: A review2008Inngår i: International Journal of Molecular Sciences, ISSN 1422-0067, E-ISSN 1422-0067, Vol. 9, nr 9, s. 1621-1651Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Lignocelluloses are often a major or sometimes the sole components of different waste streams from various industries, forestry, agriculture and municipalities. Hydrolysis of these materials is the first step for either digestion to biogas (methane) or fermentation to ethanol. However, enzymatic hydrolysis of lignocelluloses with no pretreatment is usually not so effective because of high stability of the materials to enzymatic or bacterial attacks. The present work is dedicated to reviewing the methods that have been studied for pretreatment of lignocellulosic wastes for conversion to ethanol or biogas. Effective parameters in pretreatment of lignocelluloses, such as crystallinity, accessible surface area, and protection by lignin and hemicellulose are described first. Then, several pretreatment methods are discussed and their effects on improvement in ethanol and/or biogas production are described. They include milling, irradiation, microwave, steam explosion, ammonia fiber explosion (AFEX), supercritical CO2 and its explosion, alkaline hydrolysis, liquid hot-water pretreatment, organosolv processes, wet oxidation, ozonolysis, dilute- and concentrated-acid hydrolyses, and biological pretreatments.

  • 43.
    Taherzadeh, Mohammad J.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Energy Generation from Wastes2010Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Wastes and residuals are undeniably part of human society. The accumulation of these materials and the “throw-away philosophy” result in many environmental and health issues and safety hazard problems, and prevent sustainable development in terms of resource recovery and recycling of waste materials. The carbon sources in the wastes can be converted to energy (electricity, heat, chill, fuels) and even materials using different technologies including collecting and converting current landfill gases, wet or dry anaerobic digestion to biogas, incineration, gasification and pyrolysis. Sweden has been one of the pioneers in waste management and resource recovery with more than 30 years development. The MSW of 150,000,000 inhabitants (with a typical composition and amount similar to the Nordic European countries) can be converted to about 1,000-5,000 MW electricity, depending on the technology used.

  • 44.
    Taherzadeh, Mohammad J
    Chalmers Univ of Technology.
    Ethanol from lignocellulose: physiological effects of inhibitors and fermentation strategies1999Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    Fermentative ethanol production from dilute-acid hydrolyzates of wood using the yeast Saccharomyces cerevisiae was investigated. Of known inhibitors in hydrolyzates, acetic acid, furfural and hydroxymethyl furfural (HMF) were found in the highest concentrations (up to about 10 g/l). Physiological effects of these inhibitors were studied in synthetic media. Based on these studies, on-line control of fed-batch cultivation for in-situ detoxification of the hydrolyzates was subsequently developed. The effect of acetic acid on yeast was found to strongly depend on pH. At concentration of undissociated acetic acid higher than 5 g/l, growth stopped. However, presence of the acid in the medium at low concentration (e.g. 1 g/l) increased ethanol yield and decreased the formation of fermentation by-products. Furfural (4 g/l) severely decreases the specific growth rate of S. cerevisiae in pulse addition experiments. However, the yeast was able to convert furfural to less inhibiting products, mainly by reduction to furfuryl alcohol, with a specific conversion rate of 0.6 g/g·h. A previously unidentified metabolite was also found and was characterized by mass spectrometry. Presumably, the metabolite was formed from pyruvate and furfural. HMF is less inhibiting to yeast than furfural, but remains in the medium for about 4 times longer than furfural due to a lower conversion rate. The yeast converts HMF mainly to hydroxymethyl-furfuryl alcohol and a newly identified compound probably formed from HMF and acetaldehyde. Fed-batch fermentation was suggested as a suitable mode of operation for fermenting dilute-acid hydrolyzates from the physiological studies of the inhibitors. With a suitable feed rate, it was possible to ferment also severely inhibiting spruce and birch hydrolyzates using fed-batch operation without any pretreatment of the hydrolyzates. However, the feed rate was critical in order to obtain a successful operation. A simple feedback control strategy was therefore developed, allowing the feed rate to be determined on-line, without any other input variable than the measured carbon dioxide evolution rate.

  • 45.
    Taherzadeh, Mohammad J.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    High crystalline cellulose to ethanol2010Konferansepaper (Annet vitenskapelig)
  • 46.
    Taherzadeh, Mohammad J.
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Edebo, L.
    Exploring zygomycetes fungi for industrial applications2009Inngår i: New Biotechnology, ISSN 1871-6784, E-ISSN 1876-4347, Vol. 25, nr 1, s. 83-Artikkel i tidsskrift (Fagfellevurdert)
  • 47.
    Taherzadeh, Mohammad J
    et al.
    Högskolan i Borås, Akademin för textil, teknik och ekonomi. Department of Biotechnology, University of Isfahan.
    Esmaeili, A.
    Department of Biology, University of Isfahan.
    Rabbani, M.
    Department of Biology, University of Isfahan.
    Gamma aminobutyric acid (GABA) production using acid lactic bacteria2014Inngår i: Journal of Babol University of Medical Sciences, Vol. 16, nr 8, s. 46-56Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    BACKGROUND AND OBJECTIVE: Gamma-aminobutyric acid (GABA) is a non-protein amino acid that can be found broadly in all organisms. GABA is synthesized by glutamate decarboxylase (GAD). Therefore, GABA production depends on biochemical properties of this enzyme. GABA has several physiological functions such as hypotensive activity, insomnia, depression, as well as diuretic effects. Bacteria, fungi and yeast produce considerable amount of GABA. Among bacteria, acid lactic bacteria due to their physiological and safety properties have been considered. These bacteria are used in food industry and act as probiotics in digestive system. The aim of this study was to identify and introduce GABA producing acid lactic bacteria.

    METHODS: In this paper using data banks such as PubMed and Google scholar and key words such as GABA producing acid lactic bacteria, isolation sources of them, factors that affect GABA production, acid lactic bacteria glutamate decarboxylase properties, glutamate decarboxylase gene cloning and regulation of them, the potential applications of GABA producing acid lactic bacteria and strain screenings have been reviewed.

    FINDINGS: Data from variety of papers showed that production of GABA using acid lactic bacteria is safe and biocompatible. This may lead to GABA rich fermented products.

    CONCLUSION: Results of this study showed that natural GABA has significant effects on human health. Therefore it seems acid lactic bacteria are the most suitable sources for GABA production. 

  • 48.
    Taherzadeh, Mohammad J
    et al.
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Karimi, K.
    Department of Chemical Engineering, Isfahan University of Technology.
    Enzyme-based hydrolysis processes for ethanol from lignocellulosic materials: A review2007Inngår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 2, nr 4, s. 707-738Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    This article reviews developments in the technology for ethanol production from lignocellulosic materials by "enzymatic" processes. Several methods of pretreatment of lignocelluloses are discussed, where the crystalline structure of lignocelluloses is opened up, making them more accessible to the cellulase enzymes. The characteristics of these enzymes and important factors in enzymatic hydrolysis of the cellulose and hemicellulose to cellobiose, glucose, and other sugars are discussed. Different strategies are then described for enzymatic hydrolysis and fermentation, including separate enzymatic hydrolysis and fermentation (SHF), simultaneous saccharification and fermentation (SSF), non-isothermal simultaneous saccharification and fermentation (NSSF), simultaneous saccharification and co-fermentation (SSCF), and consolidated bioprocessing (CBP). Furthermore, the by-products in ethanol from lignocellulosic materials, wastewater treatment, commercial status, and energy production and integration are reviewed.

  • 49.
    Taherzadeh, Mohammad J.
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Karimi, Keikhosro
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Bioethanol: Market and production processes2008Inngår i: Biofuels refining and performance / [ed] Ahindra Nag, New York: McGraw-Hill , 2008, s. 69-106Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 50.
    Talebnia, Farid
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Pourbafrani, Mohammad
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Taherzadeh, Mohammad J.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Lundin, Magnus
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Optimization study of citrus wastes Saccharification by dilute acid hydrolysis2008Inngår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 3, nr 1, s. 108-122Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Optimization study of citrus wastes Saccharification by dilute acid hydrolysis

12 1 - 50 of 65
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