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关键词： Tissue engineering   Biomaterials   Bioreactors   Mesenchymal stem cell   Polyurethane  

摘要： The development of new technologies to produce three-dimensional and biocompatible scaffolds associated with high-end cell culture techniques have shown to be promising for the regeneration of tissues and organs. Some biomedical devices, as meniscus prosthesis, require high flexibility and tenacity and such features are found in polyurethanes which represent a promising alternative. The Poly(PCL-TMC)urethane here presented, combines the mechanical properties of PCL with the elasticity attributed by TMC and presents great potential as a cellular carrier in cartilage repair. Scanning electron microscopy showed the presence of interconnected pores in the three-dimensional structure of the material. The scaffolds were submitted to proliferation and cell differentiation assays by culturing mesenchymal stem cells in bioreactor. The tests were performed in dynamic flow mode at the rate of 0.4 mL/min. Laser scanning confocal microscopy analysis showed that the flow rate promoted cell growth and cartilage ECM synthesis of aggrecan and type II collagen within the Poly(PCL-TMC)urethane scaffolds. This study demonstrated the applicability of the polymer as a cellular carrier in tissue engineering, as well as the ECM was incremented only when under oriented flow rate stimuli. Therefore, our results may also provide data on how oriented flow rate in dynamic bioreactors culture can influence cell activity towards cartilage ECM synthesis even when specific molecular stimuli are not present. This work addresses new perspectives for future clinical applications in cartilage tissue engineering when the molecular factors resources could be scarce for assorted reasons.

关键词： Anammox   Fulvic acid   Wastewater treatment   Microbial interaction  

摘要： The long-term effect of fulvic acid (FA) on bioreactor performance and on microbial populations within the anammox process were firstly investigated in this study. The average nitrogen removal rate showed an upward trend when the influent TOC concentration of FA was 25.2-65.1 mg/L. However, when FA was increased to 80.3 mg/L, the reactor performance was slightly inhibited. In addition, judging from the particle size and settling properties, FA can promote anammox sludge granulation. After 53 days of exposure to FA, the genus Anaerolinea increased in number, while Denitratisoma decreased. Candidatus Jettenia and Candidatus Kuenenia survived and enriched in the changed environment, potentially due to the interaction between anammox bacteria and some heterotrophic bacteria, which could protect anammox bacteria from adverse environments. These results indicate that FA can change the bacterial community and trigger different microbial interaction mechanisms within the anammox reactor.

关键词： Mining effluent   Biofilter   Iron   Metal   Metal speciation   Kinetic test  

摘要： The performance of a semi-passive sulfate-reducing bioreactor (SPSRB) was studied for the treatment of highly contaminated AMD (pH = 4.2, [Fe](i): 1600 to 6400 mg/L). The potential mobility of contaminants (metals and sulfates) from AMD post-treatment residue was also evaluated (e.g. metal speciation, weathering cells) to ensure their proper management. Sodium lactate (3500 mg/L) was continuously added to three SPSRBs composed of 60% birch chips, 20% calcite, and 20% poultry manure to enhance microbial activity. The SPSRBs were very effective during the total duration of the experiment (266 days) for the removal of Fe (average removal efficiency of 97.7%), Cd (> 99.4%), Cr (99.3%), Cu (99.9%), Ni (99.2%), Pb (99.8%), Al (92.4%), and Zn (90.7%). The study of the physicochemical stability of the post-treatment residues showed a net positive neutralization potential of 22.4 kg CaCO3/t and a NP/NA ratio of 1.80. Although the metal speciation estimates revealed that Fe, Mn, Ni, and Zn were mainly retained in the biofilter as oxides or hydroxides, a significant proportion of metals were also present in the form of sulfides, or bound to organic matter as exchangeable/soluble sulfate fractions. Finally, the kinetic tests (weathering cells) confirmed the high risk of metal release if the post-treatment residues are disposed of in an oxidizing environment.

关键词： Landfill leachate   Bacterial community   Dissolved organic matters   Material balance   Predictive function  

摘要： A two-stage anoxic/oxic combined membrane bioreactor (A/O-A/O-MBR) was operated for 81 d to treat landfill leachate under different reflux ratios (R). The best performance was found under R = 150%, where the chemical oxygen demand (COD), ammonium (NH4+-N) and total nitrogen (TN) removal was 85.6%, 99.3%, and 80.7%, respectively. Particularly, the highest pollutant removal was achieved in the second-stage A/O, where the COD and TN removal capacity was 78.88 and 11.74 g/d, respectively. Meantime, DOM removal was 83.9%, where the removal of aromatic protein substances I and II, fulvic acids-like compounds, soluble microbial products and humic acids-like compounds was 93.4%, 86.4%, 72.0%, 86.6% and 59.4%, respectively. The gene functions of microbial community in the process showed that amoA, hao, nirK and nosZ, etc. were the core genes for nitrification and denitrification. The carbon source for denitrification might come from the conversion of refractory organic matters in landfill leachate.

关键词： Biomass   Biomimetic   Co-treatment   Physical pretreatment   Ruminant   Rumination  

摘要： Pretreatment of biomass feedstocks is considered necessary to increase their conversion to biofuels and other bioproducts. However, even the best chemical and physical pretreatments have disadvantages that make the development of alternative strategies to improve biomass fermentability a worthy pursuit. An interesting natural process is that of rumination, by which ruminant animals regurgitate their food for re-chewing to reduce particle size, increase surface area, and accelerate its biodegradation by the animal's mutualistic microbial community. Detailed examination of the process reveals that it is a unique, unusually effective, and energy-efficient type of physical treatment of fibrous biomass. Effectiveness and energy efficiency are gained by several unappreciated aspects of the process, including: full wetting of the biomass prior to its exposure to re-chewing;a hypsodont dentition pattern and jaw movement designed to maximize shearing and delamination (rather than cutting) of the biomass;and an effective feed sorting mechanism that results in a preferential processing of the larger particles that are in need of further grinding, rather than smaller particles whose additional grinding would provide little benefit. These nuances of the rumination process suggest designs for accomplishing similar particle size reduction and surface area increases within bioreactors during cellulosic biomass fermentation ("co -treatment"). While the rumination process has evolved within the context of allowing the ruminant animal to exploit widely available but highly fibrous feeds, it has the potential for broad applicability and improved efficiency for industrial conversion of cellulosic biomass by both pure and mixed cultures.

关键词： Bioprocessing   Manufacturing   Stirred-Tank Bioreactor   Mesenchymal  

摘要： Human mesenchymal stem/stromal cells (hMSCs) present a key therapeutic cellular intervention for use in cell and gene therapy (CGT) applications due to their immunomodulatory properties and multi-differentiation capability. Some of the indications where hMSCs have demonstrated pre-clinical or clinical efficacy to improve outcomes are cartilage repair, acute myocardial infarction, graft versus host disease, Crohn's disease and arthritis. The current engineering challenge is to produce hMSCs at an affordable price and at a commercially relevant scale whilst minimising process variability and manual, human operations. By employing bioreactors and microcarriers (due to the adherent nature of hMSCs), it is expected that production costs would decrease due to improved process monitoring and control leading to better consistency and process efficiency, and enabling economies of scale. This approach will result in off the shelf (allogeneic) hMSC-based products becoming more accessible and affordable. Importantly, cell quality, including potency, must be maintained during the bioreactor manufacturing process. This review aims to examine the various factors to be considered when developing a hMSC manufacturing process using microcarriers and bioreactors and their potential impact on the final product. As concluding remarks, gaps in the current literature and potential future areas of research are also discussed.

关键词： Air membrane bioreactor   Hollow fiber membrane   Waste gas   Biological treatment   Microbial community analysis  

摘要： The main aim of this study was to evaluate the performance of an air membrane bioreactor (aMBR) for the treatment of gas-phase methanol. A laboratory-scale hollow fiber aMBR was operated for 150 days, at inlet methanol concentrations varying between 2 and 30 g m(-3) and at empty bed residence times (EBRT) of 30,10 and 5 s. Under steady-state conditions, a maximum methanol removal efficiency (RE) of 98% was obtained at an EBRT of 30 s and a decrease in RE of methanol was observed at lower EBRTs. On increasing the inlet loading rate, some portion of gas-phase MeOH was stripped into the liquid phase due to its solubility in water. Under transient conditions, the MeOH removal efficiency dropped from an average value of 95%-90% after 5 h of 10-fold shock load and dropped from an average value of 95%-88% under 5-fold increase in shock load. During transient-state tests, the aMBR performed well under different upset loading conditions and a drop in RE of similar to 5-10% was observed. However, the aMBR performance was restored within 1-2 days when pre-shock conditions were restored. The results from microbial structure analysis revealed a big shift of the dominant methanol degrader, from Candida boidinii strain TBRC 217 to Xanthobacter sp. and Fusicolla sp., respectively. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： monoclonal antibodies (mAbs) maximization   hybridoma cell culture   fed-batch bioreactor dynamics optimization   raw material consumption   time stepwise operating policy  

摘要： Production of monoclonal antibodies (mAbs) is a well-known method used to synthesize a large number of identical antibodies, which are molecules of huge importance in medicine. Due to such reasons, intense efforts have been invested to maximize the mAbs production in bioreactors with hybridoma cell cultures. However, the optimal control of such sensitive bioreactors is an engineering problem difficult to solve due to the large number of state-variables with highly nonlinear dynamics, which often translates into a non-convex optimization problem that involves a significant number of decision (control) variables. Based on an adequate kinetic model adopted from the literature, this paper focuses on developing an in-silico (model-based, offline) numerical analysis of a fed-batch bioreactor (FBR) with an immobilized hybridoma culture to determine its optimal feeding policy by considering a small number of control variables, thus ensuring maximization of mAbs production. The obtained time stepwise optimal feeding policies of FBR were proven to obtain better performances than those of simple batch operation (BR) for all the verified alternatives in terms of raw material consumption and mAbs productivity. Several elements of novelty (i-iv) are pointed out in the "conclusions" section (e.g., considering the continuously added biomass as a control variable during FBR).

关键词： AnMBR   2-Chlorophenol   Satisfactory performance   Membrane fouling   Shock load  

摘要： An anaerobic membrane bioreactor (AnMBR) was used to treat low to high (5-200 mg/L) concentrations of 2-chlorophenol (2-CP) wastewater. The AnMBR achieved high and stable chemical oxygen demand removal and 2-CP removal with an average value of 93.2% and 94.2% under long hydraulic retention times (HRTs, 48-96 h), respectively. 2-CP removal efficiency of 98.6 mg/L/d was achieved with 2-CP concentration of 200 mg/L, which was much higher than that of other anaerobic bioreactors. Furthermore, volatile fatty acids didn't accumulate under high 2-CP loading. Long HRTs significantly reduced the membrane fouling as the fouling rate (0.90 x 10(9) -5.44 x 10(9) m(-1) h(-1)) was low. Spirochaetaceae and Methanosaeta were the dominant microbes responsible for dechlorination, methanogenesis, and shock resistance. All these results demonstrate that this AnMBR operated under long HRTs is good and robust for fluctuating chlorophenols wastewater treatment, which has high potential for treating fluctuating refractory organics wastewater with the low membrane fouling rate.

关键词： aerobic granulation   boric acid   chitosan   denaturing gradient gel electrophoresis   real-time PCR   upflow aerobic reactor  

摘要： Compared to the conventional activated sludge, granular sludge has many advantages like good settling ability, high biomass retention and ability to withstand a high organic loading rate. In this study, the effects of boric acid and chitosan addition on granule formation was investigated in a novel Custom-made upflow aerobic granular sludge reactor for 22 days. According to the microscopic results, granulation in all reactors started at 5-7 days. The polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) results indicate the evolution of the bacterial community during the granulation process. In addition, high pressure liquid chromatography (HPLC) analysis showed that 100 mg/L of terephthalic acid (TA) was totally degraded in all reactors during 24 hours period. To date, chitosan was generally used in anaerobic granulation studies. Thus, there is little known about the role of chitosan in aerobic granulation. The findings in this study constitute important information about the process of granule formation and the factors that are essential to aerobic granulation.