| 1. |
- Abahazi, Emese, et al.
(författare)
-
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%).
|
|
| 2. |
- Al-Mamun, Abdullah, et al.
(författare)
-
Recent advances in microbial electrosynthesis system : Metabolic investigation and process optimization
- 2023
-
Ingår i: Biochemical engineering journal. - : Elsevier. - 1369-703X .- 1873-295X. ; 196
-
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.
|
|
| 3. |
- Bagherpour, Mohammad Bagher, et al.
(författare)
-
Effects of irrigation and water content of packings on alpha-pinene vapours biofilteration performance
- 2005
-
Ingår i: Biochemical engineering journal. - : Elsevier. - 1369-703X .- 1873-295X. ; 24:3, s. 185-193
-
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.
|
|
| 4. |
- Bhatnagar, Amit, et al.
(författare)
-
Adsorptive removal of cobalt from aqueous solution by utilizing lemon peel as biosorbent
- 2010
-
Ingår i: Biochemical engineering journal. - : Elsevier BV. - 1369-703X .- 1873-295X. ; 48:2, s. 181-186
-
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.
|
|
| 5. |
|
|
| 6. |
- Caspeta-Guadarrama, Luis, 1974
(författare)
-
High cell-density cultivation in batch mode for plasmid DNA production by a metabolically engineered E. coli strain with minimized overflow metabolism
- 2011
-
Ingår i: Biochemical Engineering Journal. - 1873-295X .- 1369-703X. ; 56:3, s. 165-171
-
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.
|
|
| 7. |
- Charoenrat, Theppanya, et al.
(författare)
-
Increased total air pressure versus oxygen limitation for enhanced oxygen transfer and product formation in a Pichia pastoris recombinant protein process
- 2006
-
Ingår i: Biochemical engineering journal. - : Elsevier BV. - 1369-703X .- 1873-295X. ; 30:2, s. 205-211
-
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.
|
|
| 8. |
- Hatzinikolaou, Dimitris G., et al.
(författare)
-
Modeling of the simultaneous hydrolysis-ultrafiltration of whey permeate by a thermostable beta-galactosidase from Aspergillus niger
- 2005
-
Ingår i: Biochemical engineering journal. - : Elsevier BV. - 1369-703X .- 1873-295X. ; 24:2, s. 161-172
-
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.
|
|
| 9. |
- Haykir, N. I., et al.
(författare)
-
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.
|
|
| 10. |
|
|
