| 1. |
- de Maré, Lena, et al.
(författare)
-
A cultivation technique for E. coli fed-batch cultivations operating close to the maximum oxygen transfer capacity of the reactor
- 2005
-
Ingår i: Biotechnology Letters. - : Springer Science and Business Media LLC. - 0141-5492 .- 1573-6776. ; 27:14, s. 983-990
-
Tidskriftsartikel (refereegranskat)abstract
- A cultivation strategy combining the advantages of temperature-limited fed-batch and probing feeding control is presented. The technique was evaluated in fed-batch cultivations with E. coli BL21(DE3) producing xylanase in a 3 liter bioreactor. A 20% increase in cell mass was achieved and the usual decrease in specific enzyme activity normally observed during the late production phase was diminished with the new technique. The method was further tested by growing E. coli W3110 in a larger bioreactor (50 l). It is a suitable cultivation technique when the O2 transfer capacity of the reactor is reached and it is desired to continue to produce the recombinant protein.
|
|
| 2. |
- Zhang, Shan, et al.
(författare)
-
Prospective life cycle assessment of a flexible all-organic battery
- 2022
-
Ingår i: Journal of Cleaner Production. - : Elsevier. - 0959-6526 .- 1879-1786. ; 373
-
Tidskriftsartikel (refereegranskat)abstract
- Strong interest from researchers and industry is accelerating development of flexible energy storage technologies for future flexible devices. It is critical to consider the environmental perspective in early development of new emerging technologies. In this study, cradle-to-factory gate prospective life cycle assessment (LCA) was per-formed on production of an all-organic battery with conductive redox polymers as electrode material. To gain a better understanding of the environmental performance of the all-organic battery, a flexible lithium-ion (Li-ion) battery with lithium titanate oxide and lithium cobalt oxide as electrode active materials was modeled as reference. Main environmental impacts of the all-organic battery were attributable to anode and cathode pro-duction, with electrode backbones being the main contributors. Solvents, catalysts, waste treatment, energy, and bromine were key individual contributors. Comparison with the flexible Li-ion battery indicated inferior envi-ronmental performance of the all-organic battery due to its relatively low specific energy (Wh/kg) and large amount of materials needed for production of its electrode backbones. Sensitivity analysis showed that changing scaling-up parameters and the production route of 3,4-ethylenedioxythiophene (a precursor of electrode back-bones) strongly influenced the results. In order to lower the environmental impacts of the all-organic battery, future research should focus on designing a short production chain with lower material inputs of electrode backbones, increasing battery cycle life, and improving the specific energy of the battery. In addition, relevant recommendations were provided for prospective LCAs of upscaled systems.
|
|
| 3. |
- Lindahl, Sofia, et al.
(författare)
-
Exploring the possibility of using a thermostable mutant of β-glucosidase for rapid hydrolysis of quercetin glucosides in hot water
- 2010
-
Ingår i: Green Chemistry. - : The Royal Society of Chemistry. - 1463-9262 .- 1463-9270. ; 12:1, s. 159-168
-
Tidskriftsartikel (refereegranskat)abstract
- The antioxidant quercetin was extracted from yellow onion waste and converted to its aglycone form by a combination of subcritical water extraction and enzymatic hydrolysis. The hydrolytic step was catalysed by a double residue (N221S, P342L) mutant of the thermostable beta-glucosidase (TnBgl1A), isolated from the thermophile Thermotoga neapolitana and cloned and produced in E. coli. The activity of wt TnBgl1A was shown to be dependent on the position of the glucosylation on the quercetin backbone, favouring hydrolysis of quercetin-4'-glucoside over quercetin-3-glucoside. The mutated variant of the enzyme harboured a mutation in the +2 sub-site (N221S) and showed increased catalytic efficiency in quercetin-3-glucoside hydrolysis and also to a certain extent hydrolysis of quercetin-4'-glucoside. The mutated enzyme was used directly in yellow onion extracts, prepared by subcritical water extraction, resulting in complete hydrolysis of the glucosylated flavonoids quercetin-3,4'-diglucoside, quercetin-4'-glucoside, quercetin-3-glucoside, isorhamnetin-4'-glucoside and isorhamnetin-3,4'-diglucoside. To complete hydrolysis within five minutes, 3 mg of TnBgl1A_N221S was used per gramme of onion (dry weight). A life cycle assessment was done to compare the environmental impact of the new method with a conventional solid-liquid extraction-and-hydrolysis method utilising aqueous methanol and hydrochloric acid. Comparison of the methods showed that the new method is preferable regarding primary energy consumption and global warming potential. Another advantage of this method is that handling of toxic chemicals (methanol and HCl) is avoided. This shows that combined subcritical water extraction/enzyme hydrolysis is both a fast and sustainable method to obtain quercetin from onion waste.
|
|
| 4. |
- Ramchuran, Santosh, et al.
(författare)
-
Production of heterologous thermostable glycoside hydrolases and the presence of host-cell proteases in substrate limited fed-batch cultures of Escherichia coli BL21(DE3)
- 2002
-
Ingår i: Applied Microbiology and Biotechnology. - : Springer Science and Business Media LLC. - 1432-0614 .- 0175-7598. ; 60:4, s. 408-416
-
Tidskriftsartikel (refereegranskat)abstract
- Metabolic stress is a phenomenon often discussed in conjunction with recombinant protein production in Escherichia coli. This investigation shows how heterologous protein production, and the presence of host cell proteases is related to: i) IPTG induction, ii) cell mass concentration at the time of induction and iii) the presence of metabolites (glutamic acid or those from TSB) during the post induction phase of high-cell-density (HCD) fed-batch cultivations. Two thermostable xylanase variants and one thermostable cellulase, all originating from Rhodothermus marinus were expressed in E. coli strain BL21 (DE3). A three-fold difference in the specific activity of both xylanase variants [between 7000 and 21000 U / (g cdw)], was observed under the different conditions tested. Upon induction at high cell-mass concentrations employing a nutrient feed devoid of the metabolites above, the specific activity of the xylanase variants, was initially higher but decreased 2-3 h into the post induction phase and simultaneously protease activity was detected. Furthermore, protease activity was detected in all induced cultivations employing this nutrient feed, but was undetected in uninduced control cultivations (final cell mass concentration of 40 g/L), as well as in induced cultivations employing metabolite supplemented nutrient feeds. By contrast, maximum specific cellulase activity [between 700 and 900 U / (g cdw)] remained relatively unaffected in all cases. We have established that detectable host cell proteases was not the primary reason for the post-induction activity decrease observed under certain conditions, and possible causes for the differing production levels of heterologous proteins are discussed.
|
|
| 5. |
- Åkesson, Mats, et al.
(författare)
-
On-line Detection of Acetate Formation in Escherichia coli Cultures using Dissolved Oxygen Responses to Feed Transients
- 1999
-
Ingår i: Biotechnology and Bioengineering. - 1097-0290. ; 64:5, s. 590-598
-
Tidskriftsartikel (refereegranskat)abstract
- Recombinant protein production in Escherichia coli can be significantly reduced by acetate accumulation. It is demonstrated that acetate production can be detected on-line with a standard dissolved oxygen sensor by superimposing short pulses to the substrate feed rate. Assuming that acetate formation is linked to a respiratory limitation, a model for dissolved oxygen responses to transients in substrate feed rate is derived. The model predicts a clear change in the character of the transient response when acetate formation starts. The predicted effect was verified in fed-batch cultivations of E. coli TOPP1 and E. coli BL21(DE3), both before and after induction of recombinant protein production. It was also observed that the critical specific glucose uptake rate, at which acetate formation starts, was significantly decreased after induction. On-line detection of acetate formation with a standard sensor opens up new possibilities for feedback control of substrate feeding.
|
|
| 6. |
- Grim, Johanna, et al.
(författare)
-
Demand-Orientated Power Production from Biogas: Modeling and Simulations under Swedish Conditions
- 2015
-
Ingår i: Energy and Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 29, s. 4066-4075
-
Tidskriftsartikel (refereegranskat)abstract
- The total share of intermittent renewable electricity is increasing, intensifying the need for power balancing in future electricity systems. Demand-orientated combined heat and power (CHP) production from biogas has potential for this purpose. An agricultural biogas plant, using cattle manure and sugar beet for biogas and CHP production, was analyzed here. The model Dynamic Biogas plant Model (DyBiM) was developed and connected to the Anaerobic Digestion Model No. 1 (ADM1). Flexible scenarios were simulated and compared against a reference scenario with continuous production, to evaluate the technical requirements and economic implications of demand-orientated production. The study was set in Swedish conditions regarding electricity and heat price, and the flexibility approaches assessed were increased CHP and gas storage capacity and feeding management. The results showed that larger gas storage capacity was needed for demand-orientated CHP production but that feeding management reduced the storage requirement because of fast biogas production response to feeding. Income from electricity increased by 10%, applying simple electricity production strategies to a doubled CHP capacity. However, as a result of the currently low Swedish diurnal electricity price variation and lack of subsidies for demand-orientated electricity production, the increase in income was too low to cover the investment costs. Nevertheless, DyBiM proved to be a useful modeling tool for assessing the economic outcome of different flexibility scenarios for demand-orientated CHP production.
|
|
| 7. |
- Janke, Leandro, et al.
(författare)
-
Optimizing power-to-H-2 participation in the Nord Pool electricity market: Effects of different bidding strategies on plant operation
- 2020
-
Ingår i: Renewable Energy. - : Elsevier BV. - 0960-1481. ; 156, s. 820-836
-
Tidskriftsartikel (refereegranskat)abstract
- The operation of power-to-X systems requires measures to control the cost and sustainability of electricity purchased from spot markets. This study investigated different bidding strategies for the day-ahead market with a special focus on Sweden. A price independent order (PIO) strategy was developed assisted by forecasting electricity prices with an artificial neural network. For comparison, a price dependent order (PDO) with fixed bid price was used. The bidding strategies were used to simulate H2 production with both alkaline and proton exchange membrane electrolysers in different years and technological scenarios. Results showed that using PIO to control H2 production helped to avoid the purchase of expensive and carbon intense electricity during peak loads, but it also reduced the total number of operating hours compared to PDO. For this reason, under optimal conditions for both bidding strategies, PDO resulted in an average of 10.9% lower levelised cost of H2, and more attractive cash flows and net present values than PIO. Nevertheless, PIO showed to be a useful strategy to control costs in years with unexpected hourly price behaviour such as 2018. Furthermore, PIO could be successfully demonstrated in a practical case study to fulfil the on-demand requirement of an industrial captive customer.
|
|
| 8. |
|
|
| 9. |
- Nordberg, Axel, et al.
(författare)
-
Highly Adhesive Phenolic Compounds as Interfacial Primers for Bone Fracture Fixations
- 2010
-
Ingår i: ACS APPLIED MATERIALS & INTERFACES. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 2:3, s. 654-657
-
Tidskriftsartikel (refereegranskat)abstract
- Bone fractures are today scabilized with screws and metal plates. More complicated Fractures require alternative treatments that exclude harsh surgical conditions. By adapting the benign and UV initiated thiol-ene reaction, we efficiently fabricated triazine-based, fiber-reinforced adhesive patches within 2 s. To enhance their bone adhesion properties, we found that a pre-treatment step of bone surfaces with phenolic dopamine and poly(parahydroxystyrene) compounds was successful. The latter display the greatest E-module of 3.4 MPa in shear strength. All patches exhibited low cytotoxicity and can therefore find potential use in future treatments of bone fractures.
|
|
| 10. |
- Turner, Charlotta, et al.
(författare)
-
Subcritical water extraction and beta-glucosidase-catalyzed hydrolysis of quercetin glycosides in onion waste
- 2006
-
Ingår i: Green Chemistry. - : Royal Society of Chemistry (RSC). - 1463-9262 .- 1463-9270. ; 8:11, s. 949-959
-
Tidskriftsartikel (refereegranskat)abstract
- Onion waste is a renewable raw material, rich in different molecular species of the antioxidant quercetin. To utilize this resource, an environmentally sustainable procedure has been developed, using pressurized hot water to extract the quercetin species, followed by biocatalytic conversion of the quercetin glycosides to quercetin and carbohydrates. Two different recombinantly expressed thermostable beta-glucosidases, Thermotoga neapolitana beta-glucosidase A and B, were utilized as catalysts. These enzymes maintain activity at temperatures around 90 degrees C, and are therefore ideal to use in combination with hot water extraction. Our results, based on experimental design, showed that they converted quercetin glycosides to active quercetin in less than 10 min reaction time in water at 90 degrees C, pH 5.0. Experimental design showed that the optimal extraction conditions included three 5 min extraction cycles with water at 120 degrees C and 50 bars, giving a total extraction time of 15 min. Several different types of quercetin and isorhamnetin glycosides as well as kaempferol were detected in onion waste using LC-MS/MS analysis. After converting the different glycosidic compounds to their respective aglycones, the quercetin content was 10 to 50 mg g(-1) dry weight of onion waste (RSD 8%). In summary, our research demonstrates that subcritical water extraction followed by beta-glucosidase-catalyzed hydrolysis is a rapid method to determine the content of quercetin and isorhamnetin in onion samples, and is environmentally sustainable as it only uses water as solvent and enzymes as catalysts.
|
|
