| 1. |
- Abahazi, Emese, et al.
(författare)
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Covalently immobilized Trp60Cys mutant of omega‰-transaminase from Chromobacterium violaceum for kinetic resolution of racemic amines in batch and continuous-flow modes
- 2018
-
Ingår i: Biochemical engineering journal. - : Elsevier. - 1369-703X .- 1873-295X. ; 132, s. 270-278
-
Tidskriftsartikel (refereegranskat)abstract
- Covalent immobilization of an engineered omega-transaminase mutant Trp60Cys from Chromobacterium violaceum (CvTAW60C) was performed on bisepoxide-activated aminoalkyl resins. Activity of the various CvTAW60C preparations was evaluated in kinetic resolution of four racemic amines (rac-1a–d). The most active EA-G-CvTAW60C preparation (CvTAW60C attached to polymeric resin with ethylamine function activated with glycerol diglycidyl ether—EA-G) could perform the kinetic resolution of racemic 4-phenylbutan-2-amine (rac-1a) over 49% conversion up to 19 consecutive reaction cycles or in media containing up to 50% v/v DMSO as cosolvent in batch mode reactions. The immobilization process of CvTAW60C onto the EA-G resin filled in stainless steel bioreactors was also tested in flow-through mode. Kinetic resolution of three racemic amines containing aromatic moieties (rac-1a-c) was performed in continuous-flow mode resulting in easy-to-separate mixture of the corresponding ketone (2a–c) and the non-converted (R)-amine in high enantiopurity (ee(R)-1a-c ≥ 96%).
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| 2. |
- Al-Mamun, Abdullah, et al.
(författare)
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Recent advances in microbial electrosynthesis system : Metabolic investigation and process optimization
- 2023
-
Ingår i: Biochemical engineering journal. - : Elsevier. - 1369-703X .- 1873-295X. ; 196
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Tidskriftsartikel (refereegranskat)abstract
- The intensified burning of fossil fuels and the discharging of industrial wastes are severe threats to the environment. The released CO2 and organic fractions of industrial and municipal wastes exacerbate global warming. Converting the released CO2 and organic wastes into beneficial electricity and biofuel-chemicals is deemed an environmental necessity. Microbial electrosynthesis (MES) presents a promising technology for bio-electrochemical conversion of released CO2 and organic wastes into electricity and biofuel-chemicals using external-powered and/or self-powered microbial oxidation/reduction processes. The MES system consists of anodic and cathodic processes. The technology mostly relies on the capacity of electron transfer from electroactive biofilm to the electrode for reducing organics into value-added chemicals and sustaining their respiration and growth. The current review aims to summarize and explore the diversified application of electrogenic microbes and their metabolic pathways of electron transfer. It also summarizes the MES reactor design and operational parameters that influence the catalysis of biofilm and hence, the system performance. The review concludes with a critical evaluation of technical challenges that should be overcome before large-scale implementation. Furthermore, various recommendations on technical perspectives for successful implementation and application, including future research directions, are presented in this study.
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| 3. |
- Bagherpour, Mohammad Bagher, et al.
(författare)
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Effects of irrigation and water content of packings on alpha-pinene vapours biofilteration performance
- 2005
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Ingår i: Biochemical engineering journal. - : Elsevier. - 1369-703X .- 1873-295X. ; 24:3, s. 185-193
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Tidskriftsartikel (refereegranskat)abstract
- The main objective of this investigation is to determine the effect of different physical parameters on the performance of biofilters, treating hydrophobic compounds. In this respect, the effects of irrigation and water content of packings on the removal efficiency of bed in different pollutant loading rates, and gas phase flow rates, is studied. Alpha-pinene, which is produced from variety of industrial wood products, pulp and paper industries, and fragrance production units, has been selected as a model compound. Since the effectiveness of biofiltration depends strongly upon water solubility of compounds, in the case of alpha-pinene (2.5 ppm, at 25 ◦C), the process of waste gas treatment is faced with difficulties. In this paper, it is shown that performance of biofilters, treating hydrophobic contaminants, declines due to irrigation. This reduction is detected by an increase in the outlet concentration from 11% up to 22.5%. Its magnitude depends on the gas velocity inside the biofilter and outlet concentration of the bed. The result indicated that pore blocking along the bed has less effect on the performance reduction than diffusion coefficient. Also the inhibitory effects of velocity on biodegradation are considerably higher than the effects of concentration. In addition, this compost-based biofilter shows noteworthy higher elimination capacities in comparison with previous studied biofiltration systems. In this study, a maximum elimination capacity of 227 gm−3 of packing h−1 is achieved by 95% of removal efficiency. The maximum concentration in the inlet gas was 650 mgm−3.
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| 4. |
- Bhatnagar, Amit, et al.
(författare)
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Adsorptive removal of cobalt from aqueous solution by utilizing lemon peel as biosorbent
- 2010
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Ingår i: Biochemical engineering journal. - : Elsevier BV. - 1369-703X .- 1873-295X. ; 48:2, s. 181-186
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Tidskriftsartikel (refereegranskat)abstract
- The present study was undertaken to evaluate the feasibility of lemon peel waste for the removal of cobalt ions from aqueous solutions. Batch experiments were performed to study the adsorption of cobalt on lemon peel adsorbent. The maximum adsorption capacity of lemon peel adsorbent for cobalt removal was ca. 22 mg g(-1). Three simplified kinetic models viz. pseudo-first-order, pseudo-second-order, and Weber and Morris intraparticle diffusion models were tested to describe the adsorption process. Kinetic parameters, rate constants, equilibrium sorption capacities, and related correlation coefficients for kinetic models were determined. It was found that the present system of cobalt adsorption on lemon peel adsorbent could be described more favorably by the pseudo-second-order kinetic model. The adsorption process has been found to be exothermic. The results of the present study suggest that lemon peel waste can be used beneficially in treating industrial effluents containing heavy metal ions.
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| 5. |
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| 6. |
- Caspeta-Guadarrama, Luis, 1974
(författare)
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High cell-density cultivation in batch mode for plasmid DNA production by a metabolically engineered E. coli strain with minimized overflow metabolism
- 2011
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Ingår i: Biochemical Engineering Journal. - 1873-295X .- 1369-703X. ; 56:3, s. 165-171
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Tidskriftsartikel (refereegranskat)abstract
- Progress on plasmid-based (pDNA) vaccines requires simpler and efficient cultivation techniques for their production. A prevalent problem in the cultivation of Escherichia coli (the main host for pDNA vaccines production) is the aerobic production of acetate. In this work, a metabolically engineered Escherichia coli strain with strongly reduced acetate formation was tested for the production of a plasmid vaccine at high cell-densities. The wild type (W3110) and engineered (VH33) strains were cultivated in batch mode using 100g/L of initial glucose concentration. This elevated amount of glucose allowed attaining high cell-densities of strain VH33 without external substrate feeding, simplifying the cultivation process. While W3110 produced 17mg/L of pDNA and 5.3g/L of acetate, VH33 reached 40mg/L of pDNA and only 2g/L of acetate. While the plasmid supercoiling degree progressively decreased in W3110 cultivations, it remained nearly constant for VH33. These results show the successful application of cell engineering concepts for improving DNA vaccine production processes.
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| 7. |
- Charoenrat, Theppanya, et al.
(författare)
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Increased total air pressure versus oxygen limitation for enhanced oxygen transfer and product formation in a Pichia pastoris recombinant protein process
- 2006
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Ingår i: Biochemical engineering journal. - : Elsevier BV. - 1369-703X .- 1873-295X. ; 30:2, s. 205-211
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Tidskriftsartikel (refereegranskat)abstract
- Two strategies to increase the productivity of secreted Thai Rosewood beta-glucosidase in Pichia pastoris processes were evaluated. Both methods were based on increasing the oxygen transfer rate (OTR) in the process by simple means. Increasing the driving force for the diffusion from the air bubbles to the medium by elevating the air pressure, from 1.2 to 1.9 bar increased the oxygen uptake rate (OUR) by 59% while increasing the driving force by accepting oxygen limitation increased the OUR by 35%. The OTR increased less than in proportion to the increased solubility in the high-pressure process, which indicates that air bubble compression reduces the volumetric oxygen transfer coefficient (K(L)a). Even though the methanol consumption increased almost in proportion to the OTR in both processes the biomass production did not increase as much. This is explained as a higher maintenance demand for methanol in the oxygen limited (0.027 g g(-1) g(-1)) and high-pressure processes (0.035 g g(-1) g(-1)), compared to 0.022 g g(-1) g(-1) in the methanol limited reference process. However, in spite of the low effect of increasing OTR on the biomass production the total beta-glucosidase yield increased almost in proportion to the increased methanol consumption and reached highest value in the high-pressure process, while the beta-glucosidase purity was highest in the oxygen-limited process due to release of less contaminating proteins.
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| 8. |
- Hatzinikolaou, Dimitris G., et al.
(författare)
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Modeling of the simultaneous hydrolysis-ultrafiltration of whey permeate by a thermostable beta-galactosidase from Aspergillus niger
- 2005
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Ingår i: Biochemical engineering journal. - : Elsevier BV. - 1369-703X .- 1873-295X. ; 24:2, s. 161-172
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Tidskriftsartikel (refereegranskat)abstract
- A wild type strain of Aspergillus niger, denoted as BTL, produced elevated levels of β-galactosidase when grown in a low cost medium that contained wheat bran as the sole carbon and energy source. The enzyme was collected, concentrated and partially purified from the culture supernatant. Its kinetic and stability properties were thoroughly examined towards its potential use for the hydrolysis of acid whey permeate lactose. The β-galactosidase of A. niger BTL showed increased pH and thermal stability, with activation energy for the first order deactivation constant equal to 180 kJ/mol at pH 3.5. Lactose hydrolysis by the enzyme was described by Michaelis–Menten kinetics with competitive inhibition only from galactose. An integrated process, concerning the simultaneous hydrolysis–ultrafiltration of whey lactose that incorporated the specific kinetic properties of the β-galactosidase was developed and modeled. The model proved very successful in predicting the behavior of a continuous laboratory hydrolysis–ultrafiltration set up, specifically designed for that purpose. The validated model was finally used in a number of computer simulations in order to investigate the effect of the various process parameters on the overall system performance.
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| 9. |
- Haykir, N. I., et al.
(författare)
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Applications of ionic liquids for the biochemical transformation of lignocellulosic biomass into biofuels and biochemicals : A critical review
- 2023
-
Ingår i: Biochemical engineering journal. - : Elsevier B.V.. - 1369-703X .- 1873-295X. ; 193
-
Forskningsöversikt (refereegranskat)abstract
- Lignocellulosic materials are valuable resources in today's bioprocess technologies; however, their recalcitrance is a major barrier in industry regarding their conversion to microbial products. For this purpose, in this study, the synthesis of ionic liquids (ILs), its function in the hydrolysis of lignocellulosic materials, its biochemistry and possible toxic effects were investigated. In addition, the bioconversion of lignocellulosic materials pretreated with ionic liquids to biofuels (bioethanol, biobutanol, biogas and hydrogen) and various biochemicals is discussed in detail. For this, the focus is on the potential of ILs for industrial integration and use in large-scale reactors. ILs offer significant advantages due to their potential for ease of use and their features such as recovery and reuse after pretreatment. However, there are economic and technical problems that need to be solved to expand ILs in industrial systems and increase their use potential. To overcome these problems and the usability of ILs technologies in industry, techno-economic analyses has been examined and compared with traditional processes.
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| 10. |
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| 11. |
- Karlsson, Anna, et al.
(författare)
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Addition of HCl as a means to improve biogas production from protein-rich food industry waste
- 2012
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Ingår i: Biochemical engineering journal. - : Elsevier. - 1369-703X .- 1873-295X. ; 61, s. 43-48
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Tidskriftsartikel (refereegranskat)abstract
- The effect of pH on the production of biogas during anaerobic digestion of a protein-rich substrate, containing mainly slaughter house waste, was investigated. Four laboratory scale reactors (4 L liquid volume) with an organic load of 3.5 g volatile solids (VS) L-1 reactor volume day(-1), and a hydraulic retention time 24 days were run under mesophilic conditions in semi-continuous mode for 64 days. Two of the reactors were pH-regulated (target pH was 7.6 and 7.8, respectively) by adding HCl, while the other two reactors were operated as controls (pH 8.0). By the end of the experiment the pH-controlled reactors produced 0.6 L of methane g VSadded-1 day(-1), while the controls produced 0.4 L. The gas produced did in all cases have a CH4 - content of about 65%. The improvement in process performance in the pH-regulated reactors, compared to the controls, was also reflected in lower final levels of acetate, propionate, isobutyrate and 2-metylbutyrate. The laboratory-scale study showed that lowering the pH by 0.2-0.4 units by adding HCl to the reactors increased the methane yield with about 50%, indicating a considerable increase of the microbial ability to utilise the organic material for biogas production.
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| 12. |
- Katapodis, Petros, et al.
(författare)
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Optimization of Xylanase production by Chaetomium thermophilum in wheat straw using response surface methodology
- 2007
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Ingår i: Biochemical engineering journal. - : Elsevier BV. - 1369-703X .- 1873-295X. ; 35:2, s. 136-141
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Tidskriftsartikel (refereegranskat)abstract
- A 32 central composite experimental design was performed with the aim of optimizing xylanase production by Chaetomium thermophilum IMI 291753 grown on wheat straw in submerged cultures. Various carbon and nitrogen sources were consecutively optimized, and wheat straw and sodium nitrate were the selected substrates to test the effect of two variables on xylanase production. A second-order quadratic model and a response surface method showed that the optimum conditions for xylanase production were 3.9% (w/v) wheat straw and 0.7% (w/v) sodium nitrate.
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| 13. |
- Krishnamoorthy, Nishkala, et al.
(författare)
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Biocidal activity of ZnO NPs against pathogens and antioxidant activity - a greener approach by Citrus hystrix leaf extract as bio-reductant
- 2023
-
Ingår i: Biochemical Engineering Journal. - : Elsevier BV. - 1873-295X .- 1369-703X. ; 192
-
Tidskriftsartikel (refereegranskat)abstract
- Leaf extract-mediated bio-synthesis of nanoparticles has received significant attention due to low cost, feasibility, and lack of harmful solvents or toxic inorganic reducing agents. The synthesized ZnO NPs exhibited crystallite size of 17 nm, hexagonal phased wurtzite structure with the corresponding Eg value of 3.2 eV. X-Ray Diffraction and UV-DRS results imply typical ZnO NPs structural formation with slightly heightened band gap energy. Functional group, especially Zn-O bond vibrations at 880 and 432 cm−1 are identified with aid of Fourier Transform Infrared spectroscopy (FT-IR) operating in-between 4000 and 400 cm−1 respectively. Results of FESEM and HR-TEM declare spherical shaped, bush-like morphology with particle sized 26–69 ± 0.5 nm. The EDX spectrum results convey the mass percentage of Zn as 70.43% and O as 14.19%. SAED pattern of ZnO NPs demonstrates good crystalline high intense lattice planes (101) with an interplanar spacing of 0.36 nm are, well consistent with obtained XRD results. The results showed Citrus hystrix leaf extract mediated ZnO NPs deliver prominent antibacterial activities against Escherichia coli and Staphylococcus aureus and antifungal activity against Candida albicans and Aspergillus niger. ZnO NPs also possess a good antioxidant activity. An excellent IC50 value of 133.9 μg/ml is obtained for the synthesized ZnO NPs.
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| 14. |
- Nordlander, Eva, et al.
(författare)
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Investigating the possibility of applying an ADM1 based model to a full-scale co-digestion plant
- 2017
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Ingår i: Biochemical engineering journal. - : Elsevier. - 1369-703X .- 1873-295X. ; 120, s. 73-83
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated the possibility of using a model based on the anaerobic digestion model no. 1 (ADM1) on a full-scale 4000 m3 digester in order to understand how such theoretical models can be applied to a real industrial process. The industrial scale digester co-digests the organic fraction of municipal solid waste, grease trap sludge, and ley crop silage with varying feed rates and amounts of volatile solids. A year of process data was collected. Biogas flow, methane content/flow, and ammonia nitrogen were the variables that the model was best at predicting (index of agreement at 0.78, 0.61/0.77, and 0.68, respectively). The model was also used to investigate the effect of increasing the volatile solids (VS) concentration entering the digester. According to simulation results, increasing the influent VS concentration will increase biogas and methane outflow (from 1.5 million Nm3 methane to more than 2 million Nm3 methane), but decrease the amounts of biogas/methane per unit of volatile solids (from about 264 Nm3 methane per tonne VS to below 215 Nm3 methane per tonne VS).
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| 15. |
- Osadolor, Osagie A., et al.
(författare)
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Empirical and experimental determination of the kinetics of pellet growth in filamentous fungi : A case study using Neurospora intermedia.
- 2017
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Ingår i: Biochemical engineering journal. - : Elsevier B.V.. - 1369-703X .- 1873-295X. ; 124, s. 115-121
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Tidskriftsartikel (refereegranskat)abstract
- Pellet morphol. formation by filamentous fungi has gained a lot of attention because of its multiple benefits such as the ease of sepn. and smaller bioreactor vol. requirement. Most reported kinetics studies on fungal pellet growth are centered on aeration, despite the exptl. results pointing to the importance of other factors such as pH, substrates and product concn. etc., influencing the pellet formation. Hence a kinetic study on the effect of multiple factors such as aeration, substrate and product concn. and pH was done in this paper using Neurospora intermedia as a model organism, whose ability to form mycelial pellets was recently reported. The max. growth rate of the pellets under uninhibited conditions at its optimal growth pH was 0.318 h-1. The pellets were found to be inhibited by high product (ethanol) concn. with no growth occurring at 70 g L-1 and above. High substrate concn. favored the formation of loose fur-like fluffy pellets. The specific oxygen uptake rate of the pellets was between 0.27-0.9 mmol-O2 g-biomass-1h-1 depending on the pellet av. diam. The results from this kinetic study can be used for bioreactor design, operations and optimization of fermn. processes utilizing N. intermedia. [on SciFinder(R)]
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| 16. |
- Osadolor, Osagie Alex, 1987-, et al.
(författare)
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Membrane stress analysis of collapsible tanks andbioreactors
- 2016
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Ingår i: Biochemical engineering journal. - : Elsevier BV. - 1369-703X .- 1873-295X.
-
Tidskriftsartikel (refereegranskat)abstract
- Collapsible tanks, vessels or bioreactors are finding increasing usage in small/medium scaleprocesses because they offer flexibility and lower cost. However, if they are to be used atlarge scale, they need to be shown capable of handling the physical stress exerted on them.Because of their nonconventional shape and non-uniform pressure distribution, thin shellanalysis cannot be used in calculating their stress. Defining curvature in terms of pressureaddressed these challenges. Using curvature and numerical analysis, the membrane stress incollapsible tanks designed as bioreactors of volumes between 100-1000 m3 were calculated.When the liquid/gas height and static pressure are known, an equation for calculating tensionper length was developed. An equation that could calculate the liquid height from thebioreactor’s volume, dimensions and working capacity was generated. The equation gavevalues of liquid height with a maximum deviation of 3% from that calculated by curvatureanalysis. The stress values from the liquid height and tension equations had a maximumdeviation of 6% from those calculated by curvature analysis. The calculated tensile stress in a1000 m3 collapsible tank was 14.2 MPa. From these calculations, materials that optimize bothcost and safety can be selected when designing collapsible tanks.
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| 17. |
- Papaspyridi, Lefki-Maria, et al.
(författare)
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Optimization of biomass production with enhanced glucan and dietary fibres content by Pleurotus ostreatus ATHUM 4438 under submerged culture
- 2010
-
Ingår i: Biochemical engineering journal. - : Elsevier BV. - 1369-703X .- 1873-295X. ; 50:3, s. 131-138
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Tidskriftsartikel (refereegranskat)abstract
- This work was aimed at optimizing biomass production by the edible basidiomycete Pleurotus ostreatus ATHUM 4438 in a submerged process with enhanced glucan and dietary fibres content. β-Glucan from Pleurotus sp. (pleuran) has been used as food supplements due to its immunosuppressive activity. Like other dietary fibre components, oyster mushroom polysaccharides can stimulate the growth of colon microorganisms (probiotics), i.e. act as prebiotics. We used the FF MicroPlate for substrate utilization and growth monitoring. The pattern of substrate catabolism forms a substrate assimilation fingerprint which is useful in selecting media components for media optimization of maximum biomass production. Different carbon sources (95) were used and then 8 of them were tested in shake flask cultures. The effect of various organic and complex nitrogen sources on biomass production was also examined and response surface methodology based on central composite design was applied to explore the optimal medium composition. When the optimized culture medium was tested in a 20-L stirred tank bioreactor, using 57 g L−1 xylose and 37 g L−1 corn steep liquor, high yields (39.2 g L−1) of dry biomass was obtained. The yield coefficients for total glucan and dietary fibres on mycelial biomass formed were 140 ± 4 and 625 ± 9 mg g−1 mycelium dry weight, respectively.
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| 18. |
- Schwarz, Hubert, et al.
(författare)
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Monitoring of amino acids and antibody N-glycosylation in high cell density perfusion culture based on Raman spectroscopy
- 2022
-
Ingår i: Biochemical engineering journal. - : Elsevier BV. - 1369-703X .- 1873-295X. ; 182, s. 108426-
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Tidskriftsartikel (refereegranskat)abstract
- Raman spectrum based predictive models provide a process analytical technology (PAT) tool for monitoring and control of culture parameters in bioprocesses. Steady-state perfusion cultures generate a relatively stable metabolite profile, which is not conducive to modeling due to the absence of variations of culture parameters. Here we present an approach where different steady-states obtained by variation of the cell specific perfusion rate (CSPR) between 10 and 40 pL/(cell * day) with cell densities up to 100 × 106 cells/mL during the process development provided a dynamic culture environment, favorable for the model calibration. The cell density had no effect on the culture performance at similar CSPR, however a variation in the CSPR had a strong influence on the metabolism, mAb productivity and N-glycosylation. Predictive models were developed for multiple culture parameters, including cell density, lactate, ammonium and amino acids; and then validated with new runs performed at multiple or single steady-states, showing high prediction accuracy. The relationship of amino acids and antibody N-glycosylation was modeled to predict the glycosylation pattern of the product in real time. The present efficient process development approach with integration of Raman spectroscopy provides a valuable PAT tool for later implementation in steady-state perfusion production processes.
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| 19. |
- Simonsson, Christian, et al.
(författare)
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A multi-scale in silico mouse model for diet-induced insulin resistance
- 2023
-
Ingår i: Biochemical Engineering Journal. - : Elsevier BV. - 1369-703X .- 1873-295X. ; 191
-
Tidskriftsartikel (refereegranskat)abstract
- Insulin resistance causes compensatory insulin production, which in humans can eventually progress to β-cell failure and type 2 diabetes (T2D). This disease progression involves multi-scale processes, ranging from intracellular signaling to organ and whole-body level regulations, on timescales from minutes to years. T2D progression is commonly studied using overfed and genetically modified rodents. Available multi-scale data from rodents is too complex to fully comprehend using traditional analysis, not based on mathematical modelling. To help resolve these issues, we here present an in silico mouse model, featuring 38 ordinary differential equations and 78 parameters. This is the first mathematical model that simultaneously explains (chi-square cost=28.1 <51 =cut-off, p = 0.05) multi-scale mouse insulin resistance data on all three levels – cells, organs, body – ranging from minutes to months. The model predicts new independent multi-scale simulations, on e.g., weight and meal response changes, which are corroborated by our own new experimental data. The thus validated model provides insights and non-trivial predictions regarding complex non-measured processes, such as the relation between insulin resistance and insulin-dependent glucose uptake for adipose tissue. Finally, we add a β-cell failure module to the in silico mouse model to simulate different human-like scenarios of progression towards T2D. In summary, our in silico mouse model is an extendable and interactive knowledge-base for the study of T2D, which could help simulate treatment scenarios in rodents and translate results to the human situation.
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| 20. |
- Ventorim, Rafaela Zandonade, et al.
(författare)
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Genome-scale metabolic model of oleaginous yeast Papiliotrema laurentii
- 2022
-
Ingår i: Biochemical Engineering Journal. - : Elsevier BV. - 1873-295X .- 1369-703X. ; 180
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Tidskriftsartikel (refereegranskat)abstract
- Oleaginous yeasts are promising candidates as single cell oil (SCO) platforms to meet energy demand due to their high growth rate, easy scaling and the possibility of being cultivated in culture media based on lignocellulosic biomass. The oleaginous yeast Papiliotrema laurentii UFV-1 is able to reach high lipid contents in short periods, besides its composition of fatty acids is suitable in terms of quality standards required for biodiesel production. However, little is known about the regulation of its metabolism. We present here the first genome-scale metabolic reconstruction of P. laurentii, papla-GEM. The reconstruction was based on homology to another oleaginous yeast and the model was subjected to intensive manual curation throughout the reconstruction stages to find out the metabolic specificities of this yeast. The final model includes 796 genes, 2465 reactions and 2127 metabolites, and its biomass equation is based on direct measurements of all major biomass components. The validation step was performed using experimental data obtained in this work, and simulation results evaluated the growth and lipid accumulation physiology of P. laurentii. Therefore, the papla-GEM will lead to a better understanding of the metabolic capabilities of P. laurentii and thus will be useful in systems metabolic engineering approaches.
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| 21. |
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| 22. |
- Wik, Torsten, 1968, et al.
(författare)
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Low model order approximations of continuously stirred biofilm reactors with Monod kinetics
- 2006
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Ingår i: Biochemical Engineering Journal. - : Elsevier BV. - 1873-295X .- 1369-703X. ; 30:1, s. 16-25
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Tidskriftsartikel (refereegranskat)abstract
- Design of controllers and optimization of plants using biofilm reactors require dynamic models and efficient methods of simulation. Continuously stirred biofilm reactors (CSBRs) are useful model units in modeling a variety of different types of biofilm reactors. Often the reaction kinetics in the biofilm is described by a Monod expression. With standard modeling assumptions the equations describing the fast dynamics of a CSBR will then, for each substrate, be one nonlinear partial differential equation coupled with one linear ordinary differential equation. Here, it is shown how a few nonlinear ordinary first order differential equations, which may be solved with standard integration methods, can be used as a close approximation for both dynamic responses and steady state solutions. These low order models can conveniently be used in simulation software and for controller design. © 2006 Elsevier B.V. All rights reserved.
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| 23. |
- Winestrand, Sandra, et al.
(författare)
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Co-immobilization of oxalate oxidase and catalase in films for scavenging of oxygen or oxalic acid
- 2013
-
Ingår i: Biochemical engineering journal. - : Elsevier BV. - 1369-703X .- 1873-295X. ; 72, s. 96-101
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Tidskriftsartikel (refereegranskat)abstract
- Oxalate oxidase has potential to act as an oxygen scavenger in active packaging to increase the shelf-life of food and beverages, while simultaneously producing the protective packaging gas carbon dioxide. This study shows that oxalate oxidase from barley can be immobilized with retained catalytic activity through entrapment in a latex polymer matrix. Conditions for formation of film containing oxalate oxidase have been evaluated as well as effects of storage and latex on enzyme activity, migration of enzyme in films, and the ability of the latex films to resist higher temperatures. Drying of enzyme-containing latex films at 75 °C prior to conditioning at 30 °C resulted in higher activity than drying solely at 30 °C, or drying at 95 °C or 105 °C followed by conditioning at 30 °C. Storage of films in air at 4 °C for 14 days did not negatively affect the enzymatic activity. Inclusion of catalase in films with oxalate oxidase effectively prevented release of hydrogen peroxide. The results suggest that the immobilized enzyme can successfully be used both as an oxygen scavenger and as an oxalic-acid scavenger.
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| 24. |
- Zambrano, Jesús, et al.
(författare)
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Optimal steady-state design of zone volumes of bioreactors with Monod growth kinetics
- 2015
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Ingår i: Biochemical Engineering Journal. - : Elsevier BV. - 1369-703X .- 1873-295X. ; 100, s. 59-66
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Tidskriftsartikel (refereegranskat)abstract
- This paper deals with steady-state analysis and design of bioreactors consisting of a number of completely stirred tank reactors (CSTRs) in series. The study is confined to one consumed (substrate) and one consuming constituent (biomass). The specific microbial growth rate is assumed to be described by Monod kinetics. The death of biomass is assumed to be negligible. Two optimal design problems for a large number of CSTRs in series are studied: to minimize the effluent substrate concentration for a given total volume, and to minimize the total volume for a given effluent substrate concentration. As an appealing alternative to solve these problems numerically, it is proposed to consider the asymptotic case where the number of CSTRs tends to infinity. This is shown to correspond to one CSTR in series with a plug flow reactor (PFR). A CSTR with a sufficient large volume is needed to avoid wash-out of the biomass. The main result is that both design problems for the CSTR + PFR configuration have the same solution with respect to the optimal volume of the CSTR, which is given as an explicit function of the incoming substrate concentration, the volumetric flow rate and the coefficients of the Monod growth rate function. Numerical results indicate that the plug flow approach may be used as a feasible design procedure even for a reasonably low number of CSTRs in series.
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| 25. |
- Bengtsson, Simon, et al.
(författare)
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Acidogenic fermentation of industrial wastewaters: Effects of chemostat retention time and pH on volatile fatty acids production
- 2008
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Ingår i: Biochemical Engineering Journal. - : Elsevier BV. - 1369-703X. ; 40:3, s. 492-499
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Tidskriftsartikel (refereegranskat)abstract
- Acidogenic fermentation of wastewater can serve as a first step in a process for mixed culture production of polyhydroxyalkanoates (PHA) since the produced volatile fatty acids (VFA) are preferred substrates for PHA production. Acidogenic fermentation of industrial wastewaters (cheese whey permeate and three pulp and paper mill effluents) was evaluated in batch and continuous experiments. From the batch experiments, it was found that for whey and one of the paper mill effluents nearly 100% of the soluble COD was readily fermentable. In continuous chemostat experiments with these two effluents, varying the retention time (RT) and pH of the reactors exhibited significant impact on the amount and composition of VFA produced. Increasing RT resulted in increased degrees of acidification up to a maximum of 0.93 g COD of VFA per g influent SCOD at RT 95 h for whey and 0.75 gCOD/gCOD at RT 24 h for the paper mill effluent. Main fermentation products were acetate, propionate and butyrate. Acetate production was rather insensitive to RT while above RT 10 h a shift from butyrate production to propionate production with increasing RT occurred for both effluents. Increasing pH from 5 to 6 resulted in increased amount of propionate. Based on these findings the possibility of regulating PHA monomer composition and associated polymer properties by controlling RT and pH during acidogenic pretreatment was discussed. (c) 2008 Elsevier B.V. All rights reserved.
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