课程文献中心 更多>>

关键词： Bio-sensing   Bioreactor   Extracellular matrix   Nanosensors   Regenerative medicine   Scaffolds   Tissue engineering  

摘要： Bioreactors hold a lot of promise for tissue engineering and regenerative medicine applications. They have multiple uses including cell cultivation for therapeutic production and for in vitro organ modelling to provide a more physiologically relevant environment for cultures compared to conventional static conditions. Bioreactors are often used in combination with scaffolds as the nutrient flow can enhance oxygen and diffusion throughout the 3D constructs to prevent the formation of necrotic cores. A variety of scaffolds have been fabricated to achieve a structural architecture that mimic native extracellular matrix. Future developments of in vitro models will incorporate the ability to non-invasively monitor the cellular microenvironment to enhance the understanding of in vitro conditions. This review details current advancements in bioreactor and scaffold systems and provides insight on how in vitro models can be augmented for future biomedical applications.

关键词： Biofilm   Microbial respiratory activity   Phospholipid fatty acid   Microbial community   Biological response  

摘要： Deficiency of researches on biotic community-driven biofilm activity makes biofilm regulation lack of quantitative response for decades. Based on three full-scale aerobic bioreactors in wastewater treatment plants, this study for the first time linked microbial respiratory activity with phospholipid fatty acid (PLFA) of biofilm developed on fixed and suspended carriers. Results showed that C16:00, C18:00, C16:1, omega 7c, C18:1, omega 7c, C12:00 and C18:1 omega 9c were top six biomarkers of PLFA among different sources of samples and Gram-negative bacteria (G-) was more abundant than Gram-positive bacteria (G+) with average G-/G+ of 2.98. It's interesting to find defective revealing of PLFA-based biofilm activity by specific oxygen uptake rate (SOUR). Further modeling indicated that C16:00 achieved the optimal quantitative response to STOUR with the best model of composite, growth, or exponential curve (R-2 = 0.416, p = 0.005). This research was promising to provide important reference for biofilm regulation and accurate control of biofilm-based process.

关键词： gas-to-liquid hydrocarbon conversion   biocatalysis   gas-to-liquid mass transfer   process economics   reactor design   reactor hydrodynamics  

摘要： Bioreactors are of interest for gas-to-liquid conversion of stranded or waste industrial gases, such as CO, CH4, or syngas. Process economics requires reduction of bioreactor cost and size while maintaining intense production via rapid delivery of gases to the liquid phase (i.e., high k(L)a). Here, we show a novel bioreactor design that outperforms all known technology in terms of gas transfer energy efficiency (k(L)a per power density) while operating at high k(L)a (i.e., near 0.8 s(-1)). The reactor design uses a micro-jet array to break feedstock gas into a downward microbubble flow. Hydrodynamic and surfactant measurements show the reactor's advanced performance arises from its bubble breakage mechanism, which limits fluid shear to a thin plane located at an optimal location for bubble breakage. Power dissipation and k(L) are shown to scale with micro-jet diameter rather than reactor diameter, and the micro-jet array achieves improved performance compared to classical impinging-jets, ejector, or U-loop reactors. The hydrodynamic mechanism by which the micro-jets break bubbles apart is shown to be shearing the bubbles into filaments then fragmentation by surface tension rather than "cutting in half" of bubbles. Guided by these hydrodynamic insights, strategies for industrial design are given. (c) 2018 American Institute of Chemical Engineers Biotechnol. Prog., 35: e2710, 2019

关键词： Mathematical modeling   Biodegradation   Control system   Microbiological reactor   Dynamic simulation  

摘要： The paper concerns start-up of a continuous stirred tank bioreactor with biofilm for aerobic microbiological degradation of a toxic organic compound. Method for the bioreactor start-up was proposed, which is based on using a proportional controller for the control by flow rate. Numerical simulations were performed using a heterogeneous mathematical model of the bioreactor, which takes into account three phases: gas, liquid and biofilm. It was shown that using the proposed strategy results in obtaining even over 8-fold decrease of time, after which a stationary, low concentration of a toxic compound is obtained. Moreover, it decreases the risk of anoxia of microorganisms related to considerable decrease in dissolved oxygen concentration, which takes place during a standard start-up method. The efficiency of the proposed method was shown on the example of aerobic degradation of phenol for different values of the substrate concentration in the feed stream and for different values of mean residence time of the liquid in the bioreactor. (C) 2018 Published by Elsevier B.V. on behalf of Institution of Chemical Engineers.

关键词： Diclofenac (DCF)   Carbamazepine (CBZ)   Amoxicillin (AMX)   Pharmaceuticals   Electro-membrane bioreactor (eMBR)   Membrane fouling   Fouling precursors  

摘要： This study investigates the removal of selected pharmaceuticals, as recalcitrant organic compounds, from synthetic wastewater using an electro-membrane bioreactor (eMBR). Diclofenac (DCF), carbamazepine (CBZ), and amoxicillin (AMX) were selected as representative drugs from three different therapeutic groups such as anti-inflammatory, anti-epileptic, and antibiotic, respectively. An environmentally relevant concentration (10g/L) of each compound was spiked into the synthetic wastewater, and then, the impact of appending electric field on the control of membrane fouling and the removal of conventional contaminants and pharmaceutical micropollutants were assessed. A conventional membrane bioreactor (MBR) was operated as a control test. A reduction of membrane fouling was observed in the eMBR with a 44% decrease of the fouling rate and a reduction of membrane fouling precursors. Humic substances (UV254), ammonia nitrogen (NH4-N), and orthophosphate (PO4-P) showed in eMBR removal efficiencies up to 90.68 +/- 4.37, 72.10 +/- 13.06, and 100%, respectively, higher than those observed in the MBR. A reduction of DCF, CBZ, and AMX equal to 75.25 +/- 8.79, 73.84 +/- 9.24, and 72.12 +/- 10.11%, respectively, was found in the eMBR due to the enhanced effects brought by electrochemical processes, such as electrocoagulation, electrophoresis, and electrooxidation.

关键词： mammalian cell culture   Chinese hamster ovary   lactate   ammonium   process control   CO2 removal  

摘要： pH control is critical in bioreactor operations, typically realized through a two-sided control loop, where CO2 sparging and base addition are used in bicarbonate-buffered media. Though a common approach, base addition could compromise culture performance due to the potential impact from pH excursions and osmolality increase in large-scale bioreactors. In this study, the feasibility of utilizing control of sparge gas composition as part of the pH control loop was assessed in Chinese hamster ovary (CHO) fed-batch cultures. Fine pH control was evaluated in multiple processes at different setpoints in small-scale ambr (R) 250 bioreactors. Desired culture pH setpoints were successfully maintained via air sparge feedback control. As part of the pH control loop, air sparging was increased to improve CO2 removal automatically, hence increase culture pH, and vice versa. The effectiveness of this pH control strategy was seamlessly transferred from ambr (R) 250 to 200 L scale, demonstrating scalability of the proposed methodology. (c) 2018 American Institute of Chemical Engineers Biotechnol. Prog., 35: e2743, 2019

关键词： Bio-artificial bone   Bioreactor   -Tricalcium phosphate (-TCP)   Hydroxyapatite (HA)   Implant   Glucose metabolism   (CO2)-C-13 exhaust test   Sulfotransferase (SULT) 1   Vitamin A metabolism  

摘要： Bone grafting is necessary before dental implant treatment in patients with jaw bone defects. Currently, autologous bone grafting is a major burden on the patient. However, it is impossible to form a sufficient foundation for the implant with a bone-filling agent alone. It is, therefore, necessary to prepare hybrid artificial bone tissue containing osteoblasts and osteoclasts. In this study, mouse MC3T3-E1 pre-osteoblast cells and human embryonic-derived osteoblastic cell line hFOB1.19 were cultured in radial-flow bioreactors (RFB) to form three-dimensional artificial bone filled with porous beads of -tricalcium phosphate (-TCP) or hydroxyapatite (HA)which are clinically used as bone-filling agentsas cell culture carriers. When circulation culturing was performed in the growth medium for the first 10-12 days, glucose consumption was increased in the cultures with HA beads in comparison to the cultures with -TCP beads. When cultured in the differentiation culture medium during the second half of the culture period, the glucose consumption decreased in the culture with HA beads. A DNA microarray analysis suggested that osteogenesis progressed fast in three-dimensional culture filled with HA beads and that partly differentiation into osteoblasts was prominent in cultures with -TCP beads. In the growth process of MC3T3-E1 cells, the vitamin A metabolism was also activated, the synthesis and degradation of retinoic acid was enhanced, and the metabolism of the same process decreased at the end of differentiation in three-dimensional cultures. Three-dimensional circulation culture in RFB is considered to be useful for the formation of hybrid bio-artificial bone tissue.

关键词： microbial community structure   anaerobic membrane bioreactor   municipal wastewater treatment   cake sludge and bulk sludge   hydraulic retention times  

摘要： The anaerobic membrane bioreactors (AnMBR) with ring membrane module were operated under mesophilic temperature (M-AnMBR) and atmospheric temperature (A-AnMBR). Compared to the M-AnMBR, the removal efficiency of the A-AnMBR was found to be lower and the faster membrane fouling occurred in the A-AnMBR under corresponding hydraulic retention time (HRT). The MiSeq high-throughput sequencing was applied to analyze the microbial community structure. The HRT change had different effects on the community richness and diversity of the cake and bulk sludge. The abundance of phylum Proteobacteria in the M-AnMBR was higher than that in the A-AnMBR, which should account for the higher removal of nutrients in the M-AnMBR. The faster membrane fouling would occur in the A-AnMBR due to the relatively high abundance of Bacteroidetes in the bulk sludge and cake sludge. Moreover, specific comparison down to the genus level showed that the dominant abundant bacterial genera were Candidate division OP8 norank and Anaerolineaceae uncultured in the cake sludge for M-AnMBR, and were VadinHA17 norank, WCHB1-69 norank, VadinBC27 wastewater-sludge group, and Synergistaceae uncultured in the cake sludge for A-AnMBR The different representative genera with the variation of the HRTs for the two bioreactors might indicate the different performance between the two AnMBRs.

关键词： sulfadiazine   trimethoprim   microbial community   activated sludge   SRT   AOA  

摘要： The effect of antibiotics sulfadiazine and trimethoprim on activated sludge operated at 8 degrees C was investigated. Performance and microbial communities of sequencing batch reactors (SBRs) and Membrane Bioreactors (MBRs) were compared before and after the exposure of antibiotics to the synthetic wastewater. The results revealed irreversible negative effect of these antibiotics in environmentally relevant concentrations on nitrifying microbial community of SBR activated sludge. In opposite, MBR sludge demonstrated fast adaptation and more stable performance during the antibiotics exposure. Dynamics of microbial community was greatly affected by presence of antibiotics. Bacteria from classes Betaproteobacteria and Bacteroidetes demonstrated the potential to develop antibiotic resistance in both wastewater treatment systems while Actinobacteria disappeared from all of the reactors after 60 days of antibiotics exposure. Altogether, results showed that operational parameters such as sludge retention time (SRT) and reactor configuration had great effect on microbial community composition of activated sludge and its vulnerability to antibiotics. Operation at long SRT allowed archaea, including ammonium oxidizing species (AOA) such as Nitrososphaera viennensis to grow in MBRs. AOA could have an important role in stable nitrification performance of MBR-activated sludge as a result of tolerance of archaea to antibiotics. (c) 2018 American Institute of Chemical Engineers Biotechnol. Prog., 35: e2708, 2019

关键词： Anaerobic membrane bioreactor   Cheese whey   Critical flux   Cross-flow velocity   Membrane fouling  

摘要： Whey, produced in large quantities during cheese production, is a rapidly fermentable high strength wastewater characterized by a high biodegradability and low alkalinity. In this study, a lab-scale cross-flow anaerobic membrane bioreactor was used to address the commonly experienced difficulties such as unstable reactor performance and unexpected biomass losses when treating whey wastewater with conventional anaerobic reactors. The anaerobic membrane bioreactor provided a stable treatment performance, i.e. more than 90% chemical oxygen demand removal, and moderate membrane fluxes between 8 and 11 L m(-2) h(-1) could be obtained, applying a low cross-flow velocity of about 0.5 m s(-1). Short term critical flux tests revealed that higher fluxes up to 36 L m(-2) h(-1) are possible at elevated cross-flow velocities and/or reduced mixed liquor suspended solids concentrations. Sludge filterability indicated by capillary suction time and specific resistance to filtration deteriorated throughout the study. Chemical cleaning efficiency gradually decreased, indicating irreversible membrane fouling during long term operation.