| 1. |
- Abahazi, Emese, et al.
(author)
-
Covalently immobilized Trp60Cys mutant of omega‰-transaminase from Chromobacterium violaceum for kinetic resolution of racemic amines in batch and continuous-flow modes
- 2018
-
In: Biochemical engineering journal. - : Elsevier. - 1369-703X .- 1873-295X. ; 132, s. 270-278
-
Journal article (peer-reviewed)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%).
|
|
| 2. |
- Al-Mamun, Abdullah, et al.
(author)
-
Recent advances in microbial electrosynthesis system : Metabolic investigation and process optimization
- 2023
-
In: Biochemical engineering journal. - : Elsevier. - 1369-703X .- 1873-295X. ; 196
-
Journal article (peer-reviewed)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.
|
|
| 3. |
- Bagherpour, Mohammad Bagher, et al.
(author)
-
Effects of irrigation and water content of packings on alpha-pinene vapours biofilteration performance
- 2005
-
In: Biochemical engineering journal. - : Elsevier. - 1369-703X .- 1873-295X. ; 24:3, s. 185-193
-
Journal article (peer-reviewed)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.
|
|
| 4. |
- Bhatnagar, Amit, et al.
(author)
-
Adsorptive removal of cobalt from aqueous solution by utilizing lemon peel as biosorbent
- 2010
-
In: Biochemical engineering journal. - : Elsevier BV. - 1369-703X .- 1873-295X. ; 48:2, s. 181-186
-
Journal article (peer-reviewed)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.
|
|
| 5. |
|
|
| 6. |
- Caspeta-Guadarrama, Luis, 1974
(author)
-
High cell-density cultivation in batch mode for plasmid DNA production by a metabolically engineered E. coli strain with minimized overflow metabolism
- 2011
-
In: Biochemical Engineering Journal. - 1873-295X .- 1369-703X. ; 56:3, s. 165-171
-
Journal article (peer-reviewed)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.
|
|
| 7. |
- Charoenrat, Theppanya, et al.
(author)
-
Increased total air pressure versus oxygen limitation for enhanced oxygen transfer and product formation in a Pichia pastoris recombinant protein process
- 2006
-
In: Biochemical engineering journal. - : Elsevier BV. - 1369-703X .- 1873-295X. ; 30:2, s. 205-211
-
Journal article (peer-reviewed)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.
|
|
| 8. |
- Hatzinikolaou, Dimitris G., et al.
(author)
-
Modeling of the simultaneous hydrolysis-ultrafiltration of whey permeate by a thermostable beta-galactosidase from Aspergillus niger
- 2005
-
In: Biochemical engineering journal. - : Elsevier BV. - 1369-703X .- 1873-295X. ; 24:2, s. 161-172
-
Journal article (peer-reviewed)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.
|
|
| 9. |
- Haykir, N. I., et al.
(author)
-
Applications of ionic liquids for the biochemical transformation of lignocellulosic biomass into biofuels and biochemicals : A critical review
- 2023
-
In: Biochemical engineering journal. - : Elsevier B.V.. - 1369-703X .- 1873-295X. ; 193
-
Research review (peer-reviewed)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.
|
|
| 10. |
|
|
| 11. |
- Karlsson, Anna, et al.
(author)
-
Addition of HCl as a means to improve biogas production from protein-rich food industry waste
- 2012
-
In: Biochemical engineering journal. - : Elsevier. - 1369-703X .- 1873-295X. ; 61, s. 43-48
-
Journal article (peer-reviewed)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.
|
|
| 12. |
- Katapodis, Petros, et al.
(author)
-
Optimization of Xylanase production by Chaetomium thermophilum in wheat straw using response surface methodology
- 2007
-
In: Biochemical engineering journal. - : Elsevier BV. - 1369-703X .- 1873-295X. ; 35:2, s. 136-141
-
Journal article (peer-reviewed)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.
|
|
| 13. |
- Krishnamoorthy, Nishkala, et al.
(author)
-
Biocidal activity of ZnO NPs against pathogens and antioxidant activity - a greener approach by Citrus hystrix leaf extract as bio-reductant
- 2023
-
In: Biochemical Engineering Journal. - : Elsevier BV. - 1873-295X .- 1369-703X. ; 192
-
Journal article (peer-reviewed)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.
|
|
| 14. |
- Nordlander, Eva, et al.
(author)
-
Investigating the possibility of applying an ADM1 based model to a full-scale co-digestion plant
- 2017
-
In: Biochemical engineering journal. - : Elsevier. - 1369-703X .- 1873-295X. ; 120, s. 73-83
-
Journal article (peer-reviewed)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).
|
|
| 15. |
- Osadolor, Osagie A., et al.
(author)
-
Empirical and experimental determination of the kinetics of pellet growth in filamentous fungi : A case study using Neurospora intermedia.
- 2017
-
In: Biochemical engineering journal. - : Elsevier B.V.. - 1369-703X .- 1873-295X. ; 124, s. 115-121
-
Journal article (peer-reviewed)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)]
|
|
| 16. |
- Osadolor, Osagie Alex, 1987-, et al.
(author)
-
Membrane stress analysis of collapsible tanks andbioreactors
- 2016
-
In: Biochemical engineering journal. - : Elsevier BV. - 1369-703X .- 1873-295X.
-
Journal article (peer-reviewed)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.
|
|
| 17. |
- Papaspyridi, Lefki-Maria, et al.
(author)
-
Optimization of biomass production with enhanced glucan and dietary fibres content by Pleurotus ostreatus ATHUM 4438 under submerged culture
- 2010
-
In: Biochemical engineering journal. - : Elsevier BV. - 1369-703X .- 1873-295X. ; 50:3, s. 131-138
-
Journal article (peer-reviewed)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.
|
|
| 18. |
- Schwarz, Hubert, et al.
(author)
-
Monitoring of amino acids and antibody N-glycosylation in high cell density perfusion culture based on Raman spectroscopy
- 2022
-
In: Biochemical engineering journal. - : Elsevier BV. - 1369-703X .- 1873-295X. ; 182, s. 108426-
-
Journal article (peer-reviewed)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.
|
|
| 19. |
- Simonsson, Christian, et al.
(author)
-
A multi-scale in silico mouse model for diet-induced insulin resistance
- 2023
-
In: Biochemical Engineering Journal. - : Elsevier BV. - 1369-703X .- 1873-295X. ; 191
-
Journal article (peer-reviewed)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.
|
|
| 20. |
- Ventorim, Rafaela Zandonade, et al.
(author)
-
Genome-scale metabolic model of oleaginous yeast Papiliotrema laurentii
- 2022
-
In: Biochemical Engineering Journal. - : Elsevier BV. - 1873-295X .- 1369-703X. ; 180
-
Journal article (peer-reviewed)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.
|
|
| 21. |
|
|
| 22. |
- Wik, Torsten, 1968, et al.
(author)
-
Low model order approximations of continuously stirred biofilm reactors with Monod kinetics
- 2006
-
In: Biochemical Engineering Journal. - : Elsevier BV. - 1873-295X .- 1369-703X. ; 30:1, s. 16-25
-
Journal article (peer-reviewed)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.
|
|
| 23. |
- Winestrand, Sandra, et al.
(author)
-
Co-immobilization of oxalate oxidase and catalase in films for scavenging of oxygen or oxalic acid
- 2013
-
In: Biochemical engineering journal. - : Elsevier BV. - 1369-703X .- 1873-295X. ; 72, s. 96-101
-
Journal article (peer-reviewed)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.
|
|
| 24. |
- Zambrano, Jesús, et al.
(author)
-
Optimal steady-state design of zone volumes of bioreactors with Monod growth kinetics
- 2015
-
In: Biochemical Engineering Journal. - : Elsevier BV. - 1369-703X .- 1873-295X. ; 100, s. 59-66
-
Journal article (peer-reviewed)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.
|
|
| 25. |
- Bengtsson, Simon, et al.
(author)
-
Acidogenic fermentation of industrial wastewaters: Effects of chemostat retention time and pH on volatile fatty acids production
- 2008
-
In: Biochemical Engineering Journal. - : Elsevier BV. - 1369-703X. ; 40:3, s. 492-499
-
Journal article (peer-reviewed)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.
|
|
| 26. |
- Causevic, Ariana, et al.
(author)
-
Impact of critical parameters influencing enzymatic production of structured lipids using response surface methodology with water activity control
- 2022
-
In: Biochemical Engineering Journal. - : Elsevier BV. - 1369-703X. ; 187
-
Journal article (peer-reviewed)abstract
- Structured lipids with desired properties can be produced by enzymatic transesterification. This is a multistep reaction with many factors influencing both the product yield and quality. In this study, the single and combined effects of water activity, temperature and substrate ratio were studied on the reaction between high oleic sunflower oil and ethyl stearate producing 1,2-stearin-3-olein (SOS) using immobilized lipase from Rhizopus oryzae (Lipase DF “Amano” IM). Product quality was assessed as the ratio between SOS and the unwanted isomer SSO. Response surface methodology was used to create models at several time points, for increased understanding and showing the importance of the factors studied, for efficient production of structured lipids. To set the water activity, a control system based on dry/humid nitrogen gas sparging was developed. The models were found to adequately describe the effect of the factors on product yield and quality as well as being robust. For the yield, it was found that the factors influencing the enzymatic activity were highly important initially whereas factors affecting the thermodynamic equilibrium were dominating later. Increased temperature and water activity had initial positive influence that shifted to substrate ratio and a negative influence of water activity as equilibrium was approached. Product quality was mostly affected by temperature negatively, as an increased temperature promoted acyl migration.
|
|
| 27. |
- Chawade, Aakash
(author)
-
Machine learning approach for microbial growth kinetics analysis of acetic acid-producing bacteria isolated from organic waste
- 2024
-
In: Biochemical Engineering Journal. - 1369-703X. ; 202
-
Journal article (peer-reviewed)abstract
- This study proposes novel hybrid methodology that combines machine learning (ML) techniques with experi-mental strategies to analyse microbial growth-kinetics of acetic acid-producing bacteria isolated from fruit waste. This work employs ML algorithms to create different models such as multivariate linear regression (MLR), partial least square regression (PLSR), Kernel ridge regression (KRR), support vector regression (SVR), Gradient boosting regression (GBR) that captures time-dependent patterns of bacterial growth dynamics. Experiments for microbial growth kinetic analysis were conducted on best isolate of acid producing bacteria with different glucose con-centrations (1-5 %) at predefined operating conditions. It is found significant growth rate (mu) was obtained at 4 % and 5 % concentration of glucose from experimental work. 0.0588 h-1 and 0.0571 h-1 are the specific growth rate obtained at 4 % and 5 % glucose concentration respectively. Proposed ML models employed to predict growth rate kinetics theoretically at varied glucose concentrations. Comparative results indicate that GBR model exhibits superior performance in predicting growth kinetics than other models. GBR model fits the experimental results approximately with lower RMSE (0.004) than other models. This enables more accurate representation of growth patterns that is difficult to discernible through conventional analytical methods. This approach will help to understand growth kinetics of acetic acid-producing bacteria for resource recovery, wastewater treatment, and bioremediation.
|
|
| 28. |
- Gutenwik, Jan, et al.
(author)
-
Determination of protein diffusion coefficients in agarose gel with a diffusion cell
- 2004
-
In: Biochemical Engineering Journal. - : Elsevier BV. - 1369-703X. ; 19:1, s. 1-7
-
Journal article (peer-reviewed)abstract
- A diffusion cell has been used to measure the effective diffusion coefficients of proteins. The method is applied to lysozyme and BSA at different pH and ionic strength. A parameter optimization technique is used to estimate the diffusion coefficients directly from experimental data. The importance and influence of pH and ionic strength on the diffusive properties in an agarose gel have been demonstrated. A comparison with other methods showed that there is good agreement. The diffusion cell is an accurate and easy-to-use method for the measurement of protein diffusion coefficients, in spite of the long time required for a protein diffusion experiment. For smaller proteins this time can be shortened considerably by the present parameter optimization technique. (C) 2003 Elsevier B.V. All rights reserved.
|
|
| 29. |
- Hosseini, Seyed Mehdi, et al.
(author)
-
Lipase-immobilized chitosan-crosslinked magnetic nanoparticle as a biocatalyst for ring opening esterification of itaconic anhydride
- 2019
-
In: Biochemical Engineering Journal. - : Elsevier BV. - 1369-703X. ; 143, s. 141-150
-
Journal article (peer-reviewed)abstract
- Nano-magnetic biocatalyst particles, lipase-immobilized chitosan-crosslinked magnetic nanoparticles (LCMNs) were prepared by a new approach integrated from magnetic nanoparticle preparation, in situ thin layer coating and crosslinking of chitosan, and enzyme immobilization method. Thin layer coating of magnetic (Fe3O4) by crosslinked chitosan nanoparticles were prepared by reacting FeCl3.6H2O and sodium acetate in ethylene glycol, followed by suspension cross-linking using citric acid on the hydroxyl and amine group of chitosan at neutral pH. The resulting nanoparticles were used to immobilize the lipase from Candida antarctica Lipase B by linking using glutaraldehyde. The particles in each step were characterized by Fourier transform infrared spectrometry (FT-IR), vibrating-sample magnetometer measurements (VSM), and transmission electron microscopy (TEM). The magnetic biocatalyst, LCMN was found to have high storage stability and reusability due to the tightly crosslinked structure of chitosan and covalent bond immobilization. LCMNs were used for the oligomerization of itaconic anhydride by ring opening esterification, and the results were compared with those from free lipase and commercial immobilized lipase. The molecular mass of the products obtained with the biocatalysts showed similar Mn profiles with 308–381. This process represents a green approach for the preparation of both biobased magnetic biocatalysts and functional oligo-esters, and can be applied for both the immobilization of other enzymes and the utilization of photo-curable functional esters as biobased functional materials.
|
|
| 30. |
- Ivo Achu, Nges, et al.
(author)
-
Digestate liquor recycle in minimal nutrients-supplemented anaerobic digestion of wheat straw
- 2015
-
In: Biochemical Engineering Journal. - : Elsevier BV. - 1369-703X. ; 94, s. 106-114
-
Journal article (peer-reviewed)abstract
- Anaerobic digestion (AD) of minimal nutrient-supplemented wheat straw and digestate liquor recycle was evaluated in semi-continuous processes using a novel BioReactor Simulator developed for easy accurate online normalised-gas measurement. Three scenarios (i) no recycle (NR), (ii) recycle of soluble nutrient (RSN), and (iii) recycle of nutrient and microbes (RNM) were investigated in order to evaluate their respective efficiencies. Although mono-digestion of lignocellulosic biomasses are often performed with very long solid retention times (SRT), the present study demonstrated an efficient process operating with a 30-day SRT and an organic loading rate of 4 gVS/L d. The best methane yield was 303 mLCH(4)/g VS achieved in the RSN process showing a 21% improvement as compared to the NR process. The methanogenic potential of the digestates from the RSN and RNM processes was comparable to fresh inoculum indicating efficient processes. The RNM and RSN processes showed superior process stability evidenced by minimal volatile fatty acid accumulation (<0.5 g/L). As compared to the RNM process, RSN demonstrated the best performance. The improved process performance was probably due to higher nutrient and microbial concentration in the digestate-recycled processes. This study confirms the feasibility of digestate recycle in AD as an appropriate technology for treating nutrient-deficient substrates.
|
|
| 31. |
- LI, Chao, et al.
(author)
-
Assessment of regional biomass as co-substrate in the anaerobic digestion of chicken manure: Impact of co-digestion with chicken processing waste, seagrass and Miscanthus
- 2017
-
In: Biochemical Engineering Journal. - : Elsevier BV. - 1369-703X. ; 118, s. 1-10
-
Journal article (peer-reviewed)abstract
- The biochemical methane potential (BMP) assays were used as a tool to investigate methane potential of chicken manure (CM) and three co-substrates (chicken processing waste, Miscanthus and seagrass) in mono-digestion and co-digestion studies for selecting regional biomass in a bid to support the expansion of a full-scale biogas plant. Two types of kinetic models (first order and modified Gompertz models) were also applied to study the kinetics of the degradation process. The results show that all feedstock were converted to methane. The experimental methane production of chicken processing waste (CPW) and CM decreased about 27–35% compared to calculated methane production. However, the methane production rate/hydrolysis rates of mono digestion of chicken processing waste and co-digestion with CM were above 2 times quicker under the inoculum to substrate (I/S) ratio of 6 than that at the I/S ratio of 2 and 4. Miscanthus co-digestion effect was influenced by its composition and seagrass (SG) showed synergetic effect evidenced by high methane yield (which was 11–34% higher than the yield achieved from calculated BMP).
|
|
| 32. |
- Liu, Zhidan, et al.
(author)
-
Study of operational performance and electrical response on mediator-less microbial fuel cells fed with carbon- and protein-rich substrates
- 2009
-
In: Biochemical Engineering Journal. - : Elsevier BV. - 1369-703X. ; 45:3, s. 185-191
-
Journal article (peer-reviewed)abstract
- The inducement of electroactive consortia was carried Out in dual-chamber MFCS using acetate-based substrate- and a protein-rich synthetic wastewater in fed-batch mode. The characteristics of these MFCs were then compared. MFCs based on acetate-induced consortia (MFCAce) achieved more than twice higher maximum power, and one half of optimal external resistance in comparison to MFCs based on consortia (MFCPro) induced by a protein-rich wastewater. Furthermore, these MFCs exhibited various electrical responses even identical Substrate being applied. MFCAce preferred carbon-neutral substrates. whereas MFCPro exhibited better performance on nitrogen rich feedstock. In particular, for glucose-glutamic acid solution with gradually decreased glucose/glutamic acid ratio, MFCPro exhibited increasing electrical responses than MFCAce. These results suggest that it is possible to optimize the behavior and characteristics of MFC through proper selection of feeding substrate. (C) 2009 Elsevier B.V. All rights reserved.
|
|
| 33. |
- Mathew, Sindu, et al.
(author)
-
Regioselective glycosylation of hydroquinone to alpha-arbutin by cyclodextrin glucanotransferase from Thermoanaerobacter sp.
- 2013
-
In: Biochemical Engineering Journal. - : Elsevier BV. - 1369-703X. ; 79, s. 187-193
-
Journal article (peer-reviewed)abstract
- Hydroquinone glycosides were produced by transglycosylation reactions catalyzed by cyclodextrin glucanotransferase (CGTase) from Thermoanaerobacter sp. (Toruzyme (R) 3.0L). The reactions were carried out in an aqueous system containing hydroquinone (HQ) and maltodextrin as acceptor and donor substrate molecules respectively. The conditions for the synthesis of hydroquinone glucoside (alpha-arbutin) were 9 mM hydroquinone, maltodextrin (5%, w/v) in 20 mM citrate phosphate buffer, pH 5.5 and 0.025 mg/ml toruzyme at 40 degrees C for 24 h. The transfer efficiency of hydroquinone glycosylation was 31.8% and 29.2% respectively, when alpha-cyclodextrin and maltodextrin were employed as donor substrates. The major glycoside product was identified as hydroquinone-1-O-alpha-D-glucopyranoside (alpha-arbutin) on the basis of mass spectrometric, nuclear magnetic resonance analysis and component analysis of its enzymatic hydrolysates. The highest molar yield of alpha-arbutin (21.2%) was obtained when alpha-cyclodextrin was used as the donor substrate. A two step enzymatic reaction system comprising of CGTase and amyloglucosidase helped to attain a molar yield of 30% for alpha-arbutin. At room temperature the solubility of alpha-arbutin in water was determined to be 12.8 g/100 ml which is approximately 1.8 fold higher than that of hydroquinone. (C) 2013 Elsevier B.V. All rights reserved.
|
|
| 34. |
- Pateraki, Chrysanthi, et al.
(author)
-
Modelling succinic acid fermentation using a xylose based substrate
- 2016
-
In: Biochemical Engineering Journal. - : Elsevier BV. - 1369-703X. ; 114, s. 26-41
-
Journal article (peer-reviewed)abstract
- This study focuses on the development of unstructured models, including both substrate and product inhibition, that predict the cultivation of Actinobacillus succinogenes and Basfia succiniciproducens on a mixture of C5 and C6 sugars, similar to the sugar composition contained in spent sulphite liquor, the liquid waste stream from the sulphite pulping process. The main sugar monomer contained in the medium was xylose (72.6%) with galactose (12.2%), glucose (10.9%), mannose (4.2%) and arabinose (0.1%) making up the remaining sugar content. The growth inhibition caused by metabolic products (succinic, lactic, acetic, formic and mixed acids) and initial mixed sugar concentration was determined. The highest obtained succinic acid yield, final concentration and productivity in fermentations carried out in Duran bottles were 0.76 g/g, 26.0 g/L and 0.66 g/L/h for B. succiniciproducens and 0.69 g/g, 27.4 g/L and 0.60 g/L/h for A. succinogenes, respectively (the units in yield calculations are referred to grams of succinic acid produced per gram of total sugars consumed). The kinetic parameters for both strains were estimated from experimental results. The obtained R2 values for the fitted models were 0.96 for A. succinogenes and 0.94 for B. succiniciproducens. A sensitivity analysis on the obtained parameters showed that the maximum specific growth rates (μmax) and the growth associated substrate consumption parameters (γ) are the most influential model parameters for both microorganisms. The model was validated by fermentations conducted in lab-scale bioreactors showing good agreement between experimental data and model simulations.
|
|
| 35. |
- Rupar, Katarina, et al.
(author)
-
Solid Phase Micro Extraction Fibers, Calibration for Use in Biofilter Applications
- 2006
-
In: Biochemical Engineering Journal. - : Elsevier BV. - 1369-703X. ; 31:2, s. 107-112
-
Journal article (peer-reviewed)abstract
- The main purpose of this study is to develop a SPME calibration method suitable for use in evaluation of concentrations of hydrophobic substances in environmental samples. The analyte used in the experiments was alpha-pinene, a hydrophobic organic compound commonly found in wood, and therefore found in wood storage facilities, wood processing industries and wood based biofilters. The SPME fibres were calibrated for different concentrations of alpha-pinene at different temperatures and relative humidities. The method was used to evaluate the removal efficiency of a lab-scale biofilter.
|
|
| 36. |
- Zhang, Songhong, et al.
(author)
-
Hydrophobic cryogels prepared via cryo-polymerization as oil carriers for biosynthesis of sophorolipids
- 2020
-
In: Biochemical Engineering Journal. - : Elsevier BV. - 1369-703X. ; 161
-
Journal article (peer-reviewed)abstract
- Microbial synthesis of high-value biochemicals like biosurfactants using renewable substrates has attracted an intensive interest in the past decade. In this work, the bioproduction of sophorolipids was achieved by fermentation of different vegetable oils with the strain of Candida bombicola A0803 using novel hydrophobic poly(butyl methacrylate)(pBMA) cryogels as the oil substrate delivery carriers. The hydrophobic cryogels were prepared successfully via the cryo-polymerization of the reactive emulsion containing hydrophobic monomers under freezing conditions, and the characterization of cryogels was investigated experimentally. The results showed that the polymerization yields of 70 %–89 % were achieved and the cryogels had supermacropores with the maximum porosities of 92 %–96 % and good elasticity in organic solvents but rigid in water, which could provide preferable release properties for vegetable oils. Theie Young's elasticity modulus varied from 0.096 to 0.951 kPa in ethanol and acetone and the related aqueous solutions. With the pBMA cryogels as the delivery carriers of oil substrates, the maximum concentrations of sophorolipids produced for rapeseed, perilla seed and linseed oils were improved 14.5 %, 54.5 % and 53.7 %, while the maximum productivities were improved 14.5 %, 72.1 % and 42.7 % compared with those under the same fermentation condition of free carriers after 204 h–252 h of cultivation, indicating that the hydrophobic cryogels could be an interesting material for the potential applications in biosynthesis areas.
|
|
