课程文献中心 更多>>

标准号: T/ZZB 0937-2019

关键词： Metal-organic framework   Polyethersulfone   Bioactive membrane   Candida rugosa lipase   Enzyme immobilization  

摘要： In this study, the modified nanocomposite membrane of polyethersulfone (PES) with NH2-MIL-101(Cr) as a metal-organic framework (MOF) is exploited for Candida rugosa lipase (CRL) immobilization. To that end, the various amounts of NH2-MIL-101(Cr) nanoparticles are blended into PES casting solution to fabricate ultrafiltration membrane via phase inversion technique. The incorporation efficiency of NH2-MIL-101(Cr) nanoparticles on the membrane morphology is investigated using various techniques, namely atomic force microscopy (AFM), X-ray diffraction (XRD), and contact angle goniometry. In terms of water pure flux and CRL immobilization efficiency, the best performance is observed for PES-NH2-MIL1% membrane. This bioactive membrane (CRL@GA@PES-NH2-MIL1%) displays an improvement in pH and thermal stability and separation performance that makes it a fruitful candidate for using in bioreactors. The examination of the wet-and drystorage stability of CRL@GA@PES-NH2-MIL1% demonstrates the high stability for the wet bioactive membrane. The reusability inspection of CRL@GA@PES-NH2-MIL1% represents about 50% conservation of the residual activity after 12 sequential usage cycles.

关键词： Autotrophic denitrification   Microbial community structure   Micro-aerobic condition   Metabolic mechanism  

摘要： Autotrophic denitrification process is an effective strategy for treating sulfide and nitrate-enriched wastewater with low organic carbon. This study determined the sulfide oxidation and nitrate reduction rates and characterized the dominant bacteria and microbial community structure stimulated by micro-aerobic conditions in autotrophic denitrification system. With gradually increased sulfide concentration, the sulfide removal rate decreased to 37.8% at S2- = 600 mg/L, while the peak sulfide and nitrate removal rates (100% and 53.8%) were achieved at S2- = 800 mg/L with the air aeration rate of 20 mL/min. The Illumina sequencing results indicated that Thiobacillus accounted for 63% of total operational taxonomic units at generic level with sulfide concentration of 200 mg/L under anaerobic condition. However, Azoarcus, Thauera and Aliidiomorina became the dominant genera under micro-aerobic condition and their abundance significantly and positively related to the sulfide concentration and aeration rate (p < 0.05). According to the 16S metaproteomics functional composition prediction, one potential mechanism for autotrophic denitrifying under micro-aerobic condition was deduced that the oxidation of sulfide to thiosulfate further to sulfite was reinforced by trace oxygen, while the sulfite reductase activity was restrained. The decreased sulfide concentration weakened the toxicity inhibition on denitrifiers and accordingly the performance of autotrophic denitrification process was enhanced by micro-aerobic condition. (c) 2018 Elsevier B.V. All rights reserved.

关键词： Denitrification   Drainage systems   Ecotoxicological bioassays   Leachate toxicity   Nitrates   Nutrients   Woodchips bioreactors  

摘要： Woodchip-based denitrification bioreactors are widely used for treatment of high loads of nitrate pollution in agricultural run-off water. A concern raised recently, as a consequence of various organic fillings being experimented with, is whether the positive effect given by nitrate reduction could override the negative effects of such bioreactors, mainly caused by degradation of wood and the production of potentially harmful conditions for aquatic ecosystems. This paper presents the results of the experimental testing of two different filling materials: birch (BWCH) and spruce (SWCH) woodchip, and their mixture with washed gravel (WG) in volumetric ratio 10:1. We have focused on the leaching of organic carbon and phenols, and its impact on selected aquatic organisms, as well as on their denitrification efficiency and NO3- load removal rate (LRT). The results show that TOC, DOC and FNI (phenolic index) leaching is higher for the pure woodchip materials and is closely correlated with the growth inhibition of tested organisms (Vibrio fischeri, Daphnia magna, Desmodesmus subspicatus, Lemna minor). The highest denitrification efficiency and the highest load removal rates were recorded in mixed filling material (96% and 1.4 mg NO(3)(-.)dm(3).d(-1) for WG:BWCH;85% and 1.2 mg NO3-.dm(3).d(-1) forWG:SWCH). Denitrification bioreactors with mixed woodchip filling material present a promising, cheap, and extensive technology for the treatment of agricultural field run-offs. (C) 2018 Elsevier B.V. All rights reserved.

关键词： Bioreactor   somatic embryogenesis   membrane technology   temporary immersion systems   cell immobilization   hairy root culture  

摘要： Bioreactors are engineered systems capable of supporting a biologically active situation for conducting aerobic or anaerobic biochemical processes. Stability, operational ease, improved nutrient uptake capacity, time- and cost-effectiveness, and large quantities of biomass production, make bioreactors suitable alternatives to conventional plant tissue and cell culture (PTCC) methods. Bioreactors are employed in a wide range of plant research, and have evolved over time. Such technological progress, has led to remarkable achievements in the field of PTCC. Since the classification of bioreactors has been extensively reviewed in numerous reviews, the current article avoids repeating the same material. Alternatively, it aims to highlight the principal advances in the bioreactor hardware s used in PTCC rather than classical categorization. Furthermore, our review summarizes the most significant steps as well as current state-of-the-art of PTCC carried out in various types of bioreactor.

关键词： beta-galactosidase   Escherichia coli   recombinant   bioreactor   fed-batch  

摘要： beta-Galactosidase enzymes continue to play an important role in food and pharmaceutical industries. These enzymes hydrolyze lactose in its constituent monosaccharides, glucose and galactose. The industrial use of enzymes presents an increase in process costs reflecting in higher final product value. An alternative to enhance processes' productivity and yield would be the use of recombinant enzymes and their large-scale fed-batch production. The overexpression of recombinant beta-galactosidase from Kluyveromyces sp. was carried out in 2-L bioreactors using Escherichia coli strain BL21 (DE3) as host. Effect of induction time on recombinant enzyme expression was studied by adding 1 mM isopropyl thiogalactoside (IPTG) at 12 h, 18 h and 24 h of cultivation. Glucose feeding strategies were compared employing feedback-controlled DO-stat and ascendant linear pump feeding in bioreactor fed-batch cultivations. Linear feeding strategy with IPTG addition at 18 h of cultivation resulted in approximately 20 g/L and 17,745 U/L of biomass and beta-galactosidase activity, respectively. On the other hand, although the feedback-controlled DO-stat feeding strategy induced at 12 h of cultivation led to lower final biomass of 18 g/L, it presented an approximately 2.5 increase in enzymatic activity, resulting in 42,367 U/L, and most importantly it led to the most prominent specific enzymatic activity of approximately 40 U/mg(protein). Comparing to previous results, these results suggest that the DO-stat feeding is a promising strategy for recombinant beta-galactosidase enzyme production.

关键词： Compost   tomato plant residues   energy generation   insulation   heat loss   rotary drum bioreactor  

摘要： Rotary drum composters are used to produce high-quality, pathogen-free compost without weed seeds. Insulation is usually applied to small-scale composters to warm up the composted materials and enhance metabolic reactions to produce stable and mature compost within a short time. However, the relationship between the composter size and the heat loss rate is still unclear. In this study, the relationship between the composter size (designated as the ratio of surface area to volume, A(s)/V) and heat loss was analyzed and identified. To show the effect of insulation on the composting performance, two identical rotary drum bioreactors (each of A(s)/V = 9) were used to compost tomato plant residues, one insulated and the other kept without insulation. Results showed that insulation increased the overall resistance against heat loss from the bioreactor from 0.37 (m(2) degrees C W-1) to 1.12 (m(2) degrees C W-1), quickly increasing the compost temperature, and a temperature of 55-67 degrees C could be achieved and remained for three days. Therefore, mature, stable, well-aged, and high-quality compost was obtained. In the non-insulated bioreactor, the compost temperature did not exceed 37 degrees C;this caused a decline of microbial activity and the composting process temperature was only in the mesophilic range, leading to a high risk of the existence of weed seeds and pathogens in the final immature compost. Insulation is necessary for laboratory-scale and small pilot-scale bioreactors (A(s)/V 6), because heat loss is high as A(s)/V is high, whereas it is not necessary for commercial full-scale bioreactors (A(s)/V 4), because heat loss is minor as A(s)/V is low. For larger pilot-scale bioreactors (A(s)/V: 4-6), insulation cost must be considered when comparing the impact of energy saving on the composting process.

关键词： temporary immersion bioreactor   failure detection   contrast patterns  

摘要： Temporary Immersion Bioreactors (TIBs) are used for increasing plant quality and plant multiplication rates. These TIBs are actioned by mean of a pneumatic system. A failure in the pneumatic system could produce severe damages into the TIB. Consequently, the whole biological process would be aborted, increasing the production cost. Therefore, an important task is to detect failures on a temporary immersion bioreactor system. In this paper, we propose to approach this task using a contrast pattern based classifier. We show that our proposal, for detecting pneumatic failures in a TIB, outperforms other approaches reported in the literature. In addition, we introduce a feature representation based on the differences among feature values. Additionally, we collected a new pineapple micropropagation database for detecting four new types of pneumatic failures on TIBs. Finally, we provide an analysis of our experimental results together with experts in both biotechnology and pneumatic devices.

关键词： bioreactor   vibration   cell biology   PZTp   laser Doppler vibrometer (LDV)   ultrasound   finite element method  

摘要： In this present study, we propose a method for exposing biological cells to mechanical vibration. The motive for our research was to design a bioreactor prototype in which in-depth in vitro studies about the influence of vibration on cells and their metabolism can be performed. The therapy of cancer or antibacterial measures are applications of interest. In addition, questions about the reaction of neurons to vibration are still largely unanswered. In our methodology, we used a piezoelectric patch (PZTp) for inducing mechanical vibration to the structure. To control the vibration amplitude, the structure could be excited at different frequency ranges, including resonance and non-resonance conditions. Experimental results show the vibration amplitudes expected for every frequency range tested, as well as the vibration pattern of those excitations. These are essential parameters to quantify the effect of vibration on cell behavior. Furthermore, a numerical model was validated with the experimental results presenting accurate results for the prediction of those parameters. With the calibrated numerical model, we will study in greater depth the effects of different vibration patterns for the abovementioned cell types.

关键词： Antibiotic resistance genes   Temporal dynamics   Nitrifying bacteria   High-throughput sequencing   Quantitative polymerase chain reaction   Nitrification  

摘要： Analyzing the temporal dynamics of antibiotics, antibiotic resistance genes (ARGs) and the functional community could contribute to the regulation and optimization of wastewater treatment plant (WWTP) operation to achieve better antibiotics and ARGs removal performances during different seasons. However, there is little research in this area. Therefore, in this study, samples were collected from the influent, activated sludge (AS), and permeate of the membrane bioreactor (MBR) in a WWTP located in Beijing, China, biweekly over 13 months, and then analyzed systematically. The removal efficiency for all detected antibiotics through biodegradation and adsorption was 59.25 +/- 2.79%, with the highest rate of 64.79 +/- 4.68% observed in summer, indicating that the higher temperature in summer may promote biodegradation in MBR. In contrast, the elimination of antibiotics through microfiltration was negligible and unfavorable, with negative overall removal rates. However, a positive rejection rate of 9.48 +/- 8.92% was only observed in winter, indicating that a colder temperature might lead to better, but still limited, antibiotics rejection. Sulfonamides (SAs) were more likely to impose a selective pressure on their corresponding ARGs. However, due to the degradability of tetracyclines (TCs) and potential selection of ARGs in wastewater before entering WWTP, there were still TC resistances with non-detectable TCs. Significantly negative relationships were observed between the relative abundance of nitrifying bacteria (Nitrosomonas and Nitrospira) and the concentrations of certain antibiotic classes, indicating that nitrifying bacteria could be involved in the co-metabolic biodegradation of certain antibiotics through enzyme catalyzation during nitrification. (C) 2018 Elsevier B.V. All rights reserved.