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关键词： Electrohydrogenesis   Pyrite   Autotrophic denitrification   pH  

摘要： Maintenance of stable pH during pyrite-oxidizing denitrification process is important. Here, we demonstrated effective pH control (7.80 +/- 0.20-8.40 +/- 0.30) in an electrochemical-H2 and pyrite-oxidizing denitrifying bioreactor (HPR) through in situ electrohydrogenesis. HPR achieved a higher nitrate removal activity (maximum: 19.66 +/- 0.63 mg NO3--N/(L.h)) with excellent resistance to high nitrate loading (up to 400 mg/L NO3--N) compared to that of the control groups. Nitrate removal rate of HPR fitted the Michaelis-Menten kinetic model (R-2 = 0.98, p < 0.01) well, and the denitrification followed the zero-order rate law. The results of the biofilm community analyses suggested that Thauera was the dominant bacteria in the cathode biofilm of HPR and may prefer hydrogen as an electron donor for autotrophic denitrification, while the relative abundance of Pseudomonas were similar in the cathode biofilm and pyrite biofilm. This study provides a new alternative for effective pH control in denitrifying bioreactors with pyrite as a packing material.

关键词： N,N-dimethylformamide   SAnMBR   Anaerobic digestion   DMF-hydrolyzing bacteria   Denitrifying bacteria  

摘要： A submerged anaerobic membrane bioreactor (SAnMBR) was operated for the anaerobic treatment of waste-water containing approximately 2000 mg L-1N, N-dimethylformamide (DMF). Inoculated with a co-cultured inoculum, the SAnMBR obtained an excellent DMF removal under a low organic loading rate (OLR) of 3.14-4.16 g COD L-1 d(-1). However, the elevation of OLR limited hydrolysis. While the co-cultured inoculum initially contains abundant DMF-hydrolyzing bacteria with potential to hydrolyze DMF into intermediates, such as Paracoccus, Hyphomicrobium, Burkholderia, Catellibacterium, Bacillus and Bradyrhizobium, since these bacteria are facultative anaerobes which survive anaerobically, they kept decaying rather than proliferating, resulting in the weakening of the DMF-hydrolyzing ability. Each re-inoculation of new sludge only temporarily revitalized hydrolysis activity for a short period. Due to the lack of nitrate, these bacteria were unable to proliferate. This suggests that a small dose of nitrate would help to enrich these bacteria and establish a stable DMF-degrading consortium.

关键词： Gluconobacter oxydans (G. oxydans)   Xylonic acid   Immobilized cells   Pressurized pure oxygen supply   Electrodialysis  

摘要： Immobilized whole-cell fermentation has been proven to be an effective method to improve the performance and cost-effectiveness of Gluconobacter oxydans ATCC 621. In the bio-oxidation of xylose to xylonic acid, the oxygen supply through the immobilized beads is a well-known factor that limits the biocatalytic performance of Gluconobacter oxydans as obligate aerobic bacteria. The activity of immobilized cells could be efficiently improved by execution of pressurized pure oxygen supply strategy. Subsequently, in order to further enhance the production efficiency of xylonic acid and reduce end-product inhibition, online-electrodialysis was employed. Finally, a design of pressurized oxygen supply bioreactor combining with online-electrodialysis was put forward for implementing successive production of xylonic acid. The central features of this a highly integrated design are feasible and thus might enable cost-competitive bacterial xylonic acid production.

关键词： Anaerobic digestion   Membrane bioreactor   Christensenella minuta   Microbial community   Volatile fatty acids  

摘要： Substrates, the microbial community, and volatile fatty acids (VFAs) are interacting factors in anaerobic fermentation. In this paper, a microfiltration membrane was installed in a conventional reactor for sludge anaerobic fermentation, and changes in the VFA composition and the microbial community structure after the application were monitored. The membrane rejected much more polysaccharide than protein. VFA production, mainly acetic acid, was greatly enhanced by the membrane separation. The glycolytic species Christensenella minuta was significantly enriched. The explanation was inferred to be the higher retention rate of polysaccharide compared with proteins by the microfiltration. However, surprisingly, another polysaccharide using genus, Parabacteroides, did not benefit from the application of the membrane separation, suggesting more complicated mechanisms might be involved.

关键词： bacterial glycoengineering   N-glycosylation   recombinant glycoprotein   specific growth rate  

摘要： In the last decades bacterial glycoengineering emerged as a new field as the result of the ability to transfer the Campylobacter jejuni N- glycosylation machinery into Escherichia coli for the production of recombinant glycoproteins that can be used as antigens for diagnosis, vaccines, and therapeutics. However, the identification of critical parameters implicated in the production process and its optimization to jump to a productive scale is still required. In this study, we developed a dual expression glycosylation vector for the production of the recombinant glycoprotein AcrA-O157, a novel antigen that allows the serodiagnosis of the infection with enterohemorrhagic E. coli O157 in humans. Volumetric productivity was studied in different culture media and found that 2xYP had 6.9-fold higher productivity than the extensively used LB. Subsequently, bioreactor batch and exponential-fed-batch cultures were designed to determine the influence of the specific growth rate () on AcrA-O157 glycosylation efficiency, production kinetics, and specific productivity. At (max), AcrA glycosylation with O157-polysaccharide and the specific synthesis rate were maximal, constituting the optimal physiological condition for AcrA-O157 production. Our findings should be considered for the design, optimization, and scaling up of AcrA-O157 production and other recombinant glycoproteins attractive for industrial applications.

关键词： Anaerobic digestion   Biogas   Poultry slaughterhouse waste   Sewage sludge  

摘要： High amounts of organic matter and protein in slaughterhouse wastes make them a viable choice for anaerobic digestion and biogas production. The purpose of this study was to investigate potentials of biogas production from poultry slaughterhouse residues (waste and sludge) in a batch-fed anaerobic co-digestion process. In the first phase of the study, laboratory-scale experiments were conducted using 1-liter reactors at 34 degrees C with a retention time of 50 days in order to optimize digestion parameters;i.e. inoculum-substrate ratio (ISR) and total solids (TS). Based on these experiments, the ISR of 4 and the TS of 5% were determined as optimal settings for digestion over a retention time of 50 days. The highest biogas and methane yields in these experiments were respectively reported by 0.631 and 0.462 m(3)/kg-VSadded, achieved with 66% removal of volatile solids (VS). The optimized parameters obtained from the first phase were also used for verification at a larger scale (20 liters), wherein biogas and methane yields were found to be 0.574 and 0.402 m(3)/kg-VSadded;respectively. Moreover, results showed that optimal anaerobic digestion of slaughterhouse wastes in 20-liter digester could lead to 63% removal of VS and 88% reduction of chemical oxygen demand (COD) over a retention period of 42 days. The findings also indicated that decreasing ISR and increasing TS could bring about reduced pH as well as accumulation of fatty acids and ammonia, which could severely undermine yields of methanogenesis process.

关键词： Anaerobic forward osmosis membrane bioreactor   Draw solution   Entrapped cell   Fouling  

摘要： A novel entrapped cells-based-anaerobic forward osmosis membrane bioreactor (E-FOMBR) was developed. Its performance and fouling were investigated in comparison with suspended cells-based-anaerobic forward osmosis membrane bioreactor (S-FOMBR). E-FOMBR and S-FOMBR were operated under the same conditions with two widely used draw solutions (NaCl and (NH4)(2)SO4). The membrane fouling especially irreversible fouling in S-FOMBR was more severe than that in E-FOMBR regardless of the type of draw solution. The permeate flux of E-FOMBR were 1.79 and 1.85 LMH while those of S-FOMBR were 1.49 and 1.14 LMH with NaCl and (NH4)(2)SO4 as draw solutions, respectively. More deterioration of biological activity (suggested by lower organic removal) due to accumulation of salt was observed in S-FOMBR compared to E-FOMBR. Proteobacteria dominated in both FOMBRs but was more abundant in E-FOMBR than S-FOMBR. The superiority of E-FOMBR over S-FOMBR included higher and stable system performance, higher flux, and longer operation time. (C) 2019 Elsevier Ltd. All rights reserved.

关键词： Bioreactors  

摘要： A treatment pond, with an engineered bed that served as a passive vertical flow bioreactor (VFBR), was operated as part of a passive sequenced treatment system for the removal of metals from groundwater at the Mayer Ranch in Commerce, Oklahoma. The groundwater was contaminated by mining activities in west Commerce and discharges at this location occurred as artesian springs through improperly abandoned, over-drilled, and cased legacy boreholes. The VFBR operated by establishing reducing conditions in the organic bed of a pond to promote metal sorption and precipitation as sulfides. In order to verify that operations were unhindered by nonuniform flow in the VFBR, an assessment of the flow uniformity in the pond was undertaken using the streambed point velocity probe (SBPVP). The velocity data were independently validated with a water balance. The outflow calculated from the SBPVP data came within 30% of the value suggested by measured inflow rates to the pond, supporting the conclusion that the SBPVP measurements were representative of flow in the VFBR, and that flow through the bed was occurring with a satisfactory level of uniformity. Water flow rates through the reactive bed were found to be up to an order of magnitude greater than those employed in the prior column testing, contributing to metal loading rates (of Cd, Pb, Zn, Ni) estimated to be two orders of magnitude greater than those tested in the columns (4.2 x 10(4) and 3.2 x 10(2) mg/m(3)/d, respectively). However, apparently rapid chemical reactions that likely occurred close to the pond water-sediment interface contributed to the treatment system achieving its design objectives.

关键词： Adherent cells   Virus infection   Model   Oxygen uptake rate  

摘要： The production of poliovirus vaccines in adherent Vero cells in batch bioreactors usually consists of a two-step upstream process: (1) Vero cell cultivation on microcarriers and (2) poliovirus proliferation. In this study we developed a mathematical model to describe this two-step process. We introduced the calculation of the oxygen uptake rate (OUR) and a correction of measurement for the sampling effect in order to ensure the high quality data sets. Besides the data of the OUR, we selected glucose concentration, Vero cell concentration and the virus titer for daily in process control to evaluate the progress of the process. With the selected data sets, the described model can accurately describe poliovirus production by Vero cells. Several other regular in process control samples (e.g. lactate concentration, ammonia concentration, and amino acids concentration) were excluded from the model, simplifying the process control analysis and minimizing labor.