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关键词： White mulberry cell culture   Endogenous enzymatic hydrolysis   Phytostilbenoids   Bioreactor   Oxyresveratrol  

摘要： Phytostilbenes are responsible for several biological activities of mulberry (Morus sp.), which has been widely used as a raw material in health products. This study aimed to investigate the capability of Morus alba L. cell in bioreactors to produce the major bioactive stilbenes. The cell obtained from air-driven bioreactors such as round bottom, flat bottom, and air-lift vessel shape bioreactors was collected and analyzed for the levels of mulberroside A and oxyresveratrol. The results showed that the cell culture in round bottom and air-lift vessel bioreactors had higher growth rate, as compared with the cell culture in shake flasks (1.38- and 1.41-fold, respectively). The optimized culture condition to produce mulberroside A was obtained from round bottom bioreactor culture (55.56 +/- 11.41mol/L). Additionally, endogenous stilbenoid hydrolysis of cell from the bioreactor culture was examined. Under optimized hydrolytic conditions, mulberroside A in the cell was readily deglycosylated to give oxyresveratrol within 1h. These results indicated that the glycoside mulberroside A in the cell is sensitive to the endogenous enzymatic hydrolysis. Interaction of the stilbenoid components with the endogenous hydrolytic enzyme triggered by cell disruption in M. alba samples was suggested to be the major cause of the alteration of the stilbenoid levels. These findings have provided a new approach to producing glycosidic compounds and corresponding aglycones in cell culture.

关键词： ceramic membrane bioreactor   silicon carbide coatings   water purification   permeate flux   fouling   standard pore blocking model   complete pore plugging model  

摘要： In the present study, a submerged ceramic membrane bioreactor was used to effectively treat industrial wastewater. The outcome of membrane coatings on the efficacy of the membrane was investigated using a silicon carbide (SiC) coating. The flux data obtained from the study were fitted into two mathematical models, namely, the standard pore blocking model (SPBM) and the complete pore plugging model (CPPM) in order to determine the fouling mechanism. It was observed that the SPBM fit with a minimum coefficient of regression of 0.95, suggesting that particles retained on the pore walls were smaller than the average size of membrane pores. An increase in dissolved oxygen (DO) of up to 225% was noted. The significant improvement of the water quality in terms of DO, chemical oxygen demand (COD) and turbidity of coated membrane emphasizes the fact that the membrane coating increases the efficacy of water treatment in membrane bioreactors.

关键词： airlift bioreactors   golden ratio   downcomer-to-riser   hydrodynamics  

摘要： BACKGROUND The use of bioreactors that mimic industrial reality is essential if knowledge transfer is desired. This is particularly important once filamentous microbes face harsh conditions hindering the formation of biofilms in some types of bioreactors and thus diminishing their ability to perform biotransformation or production of secondary metabolites. Airlift bioreactors can circumvent such problems;however, the lack of consensus regarding riser and downcomer partition persists. The use of golden ratio is a possibility to be considered. Our proposition was to evaluate the hydrodynamic performance and mass transfer in split-rectangle-internal loop airlift bioreactors (SRILAB) using a golden ratio partition. RESULTS In a general way, results revealed that a partition of A(r)/A(d)(1.618) presents better and more desirable characteristics than A(d)/A(r)(1.618) for linear liquid velocity (U-L), mixing time (t(M)), gas holdup (epsilon(G)), and volumetric oxygen transfer coefficient (k(L)a). Such behavior was observed even when the SRILAB operated under different linear gas velocities (U-G) regimens (0.5-1.5 vvm) and Newtonian and non-Newtonian bulk fluids. CONCLUSION Such results support the idea of using the golden ratio as riser-to-downcomer partitioning parameter in airlift bioreactors. (c) 2018 Society of Chemical Industry

关键词： bubble column bioreactor   gaseous substrate   poly(3-hydroxybutyrate)   methanotroph synthesis of PHB  

摘要： Reducing the total cost of poly(3-hydroxybutyrate) (PHB) production as an attractive substitute for conventional petrochemical plastics still remains an unsolved problem. The aim of this research was the screening of PHB-producing microorganisms and selection of the best suitable medium for microbial growth and PHB production from methane. A new isolated methanotroph for MB production from natural gas was studied in different media. After selection of the suitable medium, the effect of five process variables (content of nitrogen source, disodium hydrogen phosphate, methane to air ratio, seed age, and pH) on PHB production was investigated in a bubble column bioreactor. Also, hydrodynamic and mass transfer factors (flow regime, mixing time, gas hold up, and k L a) were considered. At optimum operating conditions and engineering parameters in a bubble column, PHB content in the dried biomass reached 25 % w/w. The results showed that pH is the most important variable in the selected conditions.

关键词： TGF- superfamily   physiological oxygen   physoxia   chondrocytic marker expression   TGF- receptors   type I   type II   type III   Sp1   3   ALK1   ALK5   betaglycan   endoglin  

摘要： Culturing articular chondrocytes under physiological oxygen tension exerts positive effects on their extracellular matrix synthesis. The underlying molecular mechanisms which enhance the chondrocytic phenotype are, however, still insufficiently elucidated. The TGF- superfamily of growth factors, and the prototypic TGF- isoforms in particular, are crucial in maintaining matrix homeostasis of these cells. We employed a feedback-controlled table-top bioreactor to investigate the role of TGF- in microtissues of human chondrocytes over a wider range of physiological oxygen tensions (i.e., physoxia). We compared 1%, 2.5%, and 5% of partial oxygen pressure (pO(2)) to the normoxic' 20%. We confirmed physoxic conditions through the induction of marker genes (PHD3, VEGF) and oxygen tension-dependent chondrocytic markers (SOX9, COL2A1). We identified 2.5% pO(2) as an oxygen tension optimally improving chondrocytic marker expression (ACAN, COL2A1), while suppressing de-differentiation markers (COL1A1, COL3A1). Expression of TGF- isoform 2 (TGFB2) was, relatively, most responsive to 2.5% pO(2), while all three isoforms were induced by physoxia. We found TGF- receptors ALK1 and ALK5 to be regulated by oxygen tension on the mRNA and protein level. In addition, expression of type III co-receptors betaglycan and endoglin appeared to be regulated by oxygen tension as well. R-Smad signaling confirmed that physoxia divergently regulated phosphorylation of Smad1/5/8 and Smad2/3. Pharmacological inhibition of canonical ALK5-mediated signaling abrogated physoxia-induced COL2A1 and PAI-1 expression. Physoxia altered expression of hypertrophy markers and that of matrix metalloproteases and their activity, as well as expression ratios of specific proteins (Sp)/Kruppel-like transcription factor family members SP1 and SP3, proving a molecular concept of ECM marker regulation. Keeping oxygen levels tightly balanced within a physiological range is important for optimal chondrocytic marker expres

关键词： Membrane bioreactor   Saline wastewater treatment   Microbial community structure   Hybrid system   Halophilic microorganisms  

摘要： This work has reviewed from a microbial perspective and listed the typical studies on MBR techniques for saline wastewater treatments. When the salinity of influent is lower than 10 g/L NaCl, conventional MBR can be easily applied with adjusted operating conditions. For better biodegradation and anti-fouling ability at higher salinities (10-100 g/L), modified and hybrid MBR systems may need to be wisely designed according to the change in the microbial community and contents of EPS/SMP. To treat hypersaline wastewaters with salinities of up to 100 g/L NaCl, inoculation of halophilic bacteria has been applied in MBR works. Microbial community structures in some typical works have been discussed from a microbial perspective to benefit the identification and isolation of halophilic bacteria for future works. The following aspects are also suggested in future MBR research for saline wastewater treatment: (1) The structure design of MBR and the manufacture of advanced membranes;(2) The maintenance of the microbial biodiversity for anti-membrane fouling;(3) The metabolic mechanism for halophilic (or salt tolerant) microorganisms against salinity shocks;(4) The revolution stage and process of microorganisms during saline wastewater treatment in MBR;(5) The effects of characteristics (cell structure, shape and metabolic pathways) of microorganisms on the salt tolerance;(6) Applying halophilic microorganisms for salinities over 150 g/L NaCl. (C) 2019 Elsevier Ltd. All rights reserved.

关键词： biological nitrogen removal   step-feed   intermittent aeration   N-15-DNA-SIP   simultaneous nitrification and denitrification  

摘要： BACKGROUND The carbon in raw sewage can be reclaimed to reduce nitrate for the advanced denitrification in municipal wastewater treatment plants. A novel two-step feed oxic/anoxic/oxic-membrane bioreactor (O/A/O-MBR) process was proposed to improve carbon-use efficiency. RESULTS The flow distribution ratio (FDR), aeration mode and hydraulic loading were optimized to minimize the effluent total nitrogen (TN) concentration. When the FDR was 1:1, the intermittent aeration mode was 4 min air-on/6 min air-off and the influent flow was 5 L h(-1), the nitrate removal efficiency in the post-denitrification tank rose to 87.0% and the effluent TN concentration decreased below 15.0 mg L-1. The intermittent aeration strategy in the post oxic-membrane tank effectively promoted TN loss. The N-15-DNA based stable isotope probing experiment illustrated that Proteobacteria (35.09%), Actinobacteria (20.56%) and Chloroflexi (16.67%) dominated the intermittently aerated biofilm, and Nitrospira (9.06%) was the major nitrite oxidizing bacteria rather than Nitrobacter, representing a dominant simultaneous nitrification and denitrification pathway for nitrogen removal. CONCLUSION The integration of autotrophic nitrifying bacteria and heterotrophic denitrifying bacteria enhances the terminal TN removal under intermittent aeration mode. The two-step feed O/A/O-MBR process has the potential to solve carbon limitation in sewage wastewater treatment. (c) 2018 Society of Chemical Industry

关键词： Biohydrogen   Hydraulic retention time   Palm oil mill effluent   UASB   H-2-producing granules  

摘要： Palm oil mill effluent (POME), an agro-industrial wastewater with high solids content, was subject to hydrolysis by 1% (w/v) nitric acid in order to increase its solubility and the fermentable sugar content from its cellulosic component. POME hydrolysate was then evaluated in an up-flow anaerobic sludge blanket (UASB) bioreactor for the production of biohydrogen gas via mixed culture under thermophilic conditions. The bioreactor was fed with pre-treated POME under varied hydraulic retention time (HRT) between 48 and 3 hat constant cycle length of 24 h to test the productivity of H-2 and the stability of UASB;no washout of biomass occurred at any cycle and the system managed to recover its H-2 production rate (HPR) after initial fluctuations. In this study, H-2-producing granules (HPGs) were formed shortly after the start-up period, and were analysed by FESEM, FTIR, SEM-EDX, and their extracellular polymeric substances (EPS) content. The maximum HY and HPR achieved were 2.45 mol-H-2/mol-sugar and 11.75 L-H2/L-POME d(-1), respectively, at HRT 6 h. Acetic acid was found to be the major by-product at all HRTs, followed by butyric acid, while Clostridium spp. was found to be the most dominant H-2-producing bacteria in the system. Results suggest that UASB has a good potential for stable H-2 production with high POME digestion rate. (C) 2018 Elsevier Ltd. All rights reserved.

关键词： anaerobic osmotic membrane bioreactor   salt reversal   phosphorus recovery   salinity mitigation   microfiltration   membrane distillation  

摘要： BACKGROUND For the first time, a closed-loop anaerobic osmotic membrane bioreactor-membrane distillation (AnOMBR-MD) hybrid system integrated with periodic microfiltration (MF) extraction was investigated for simultaneous nutrient and energy recovery while maintaining high water quality for reuse. In addition, phosphorus (P) was recovered as a valuable material for agricultural purposes. RESULTS The AnOMBR-MD system exhibited excellent nutrient (>99.9%) and organic removal (almost 100%) due to double-layer filtration (FO and MD membrane). Moreover, higher methane production (0.24 L CH4/g COD) was achieved from the MF-AnOMBR process to supply a heat source for MD during the draw solution recovery process to reduce energy consumption. The MF permeate can significantly reduce the scaling potential caused by PO43- ions in bulk solution and mitigate salt accumulation in the anaerobic reactor. The P from the MF permeate was effectively recovered with an efficacy of 60 mg L-1 when the solution pH was adjusted to 12. CONCLUSION The overall performance of the MF-AnOMBR-MD hybrid system using 1.5 mol L-1 MgSO4 as the draw solution demonstrates its potential application in wastewater treatment with high nutrient recovery in the closed-loop system. Moreover, this system combined with MD in AnOMBR for draw solution recovery could achieve low energy consumption when its biogas production is utilized as heat source from the anaerobic system. (c) 2018 Society of Chemical Industry

关键词： Microalgae   CO2 microbubbles dissolver   Horizontal tubular photo-bioreactor   Ceramic shell aerator   Biomass  

摘要： A CO2 microbubbles dissolver (CMD) was developed to facilitate dissolving inorganic carbon and strengthening mass transfer in a horizontal tubular photo-bioreactor system (HTPBRS), which enhanced microalgae biomass productivity with flue gas containing 15% CO2. The influence of pump power on the bubble formation and mixing effect was found to be more obvious than that of gas flow rate. Ceramic shell aerator was more favorable for reducing bubble diameter and enhancing mass transfer than traditional rubber strip aerator. Bubble formation time decreased by 53.4% and mixing time decreased by 68.9% in response to the increased pump power. When the base area ratio of ceramic shell aerator to dissolver in the HTPBRS increased, bubble formation time decreased by 19.6% and mass transfer coefficient increased by 80.9%. The biomass yield of microalgae Chlorella PY-ZU1 with ceramic shell aerator was 30% higher than that with rubber strip aerator in the HTPBRS.