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关键词： Biomass composition   Bioremediation   Desalination process   Microalgae   Wastewater  

摘要： y This study aimed to evaluate the biomass production of Spirulina sp. LEB 18 cultivated in wastewater from the desalination process. The outdoor cultivations (210 L) were performed using as culture medium 100% wastewater supplemented with 25% of Zarrouk constituents (Tcs). In parallel, it was performed a control assay using 100% Zarrouk constituents. The biomass production in Tcs assay (1.14 g L-1) was only 9% lower than the control assay (1.25 g L-1). The Tcs assay showed a higher content of carbohydrates (52.29%), lipids (12.79%) and ash (2.69%) compared to the control assay (47.91;7.59 and 1.29%, respectively). The biomass from the control and Tcs assays had mostly monounsaturated fatty acids C15:1 and C18:2n6t. The Spirulina sp. LEB 18 could use efficiently the nutrients from the wastewater, showing high removal efficiency of NO3- (96.99%), PO4 (83.11%) and Z (96.43%). At the same time, high added value biomolecules were produced for different purposes.

关键词： acid mine drainage   iron-oxidizing bacteria   microorganism construction   sulfate reducing bacteria  

摘要： A novel modular continuous flow bioreactor system was designed to enhance the tolerance of bacteria to high concentration of heavy metal. This study evaluated the combined effect of high and low concentration levels of zinc, ferrous iron, copper, sulfate, and carbon source on the heavy metals and sulfate removal efficiencies. Statistically valid Plackett-Burman design (PBD) of experiments was employed to carry out this study. A maximum removal for each of zinc, copper, iron, and sulfate was 99.08%, 99.13%, 94.83%, and 58.89%, respectively. Analysis of variance (ANOVA) of zinc, copper, and sulfate reduction revealed that the effect due to zinc was highly significant (p < 0.05). To establish the roles of iron-oxidizing bacteria (IOB) and sulfate reducing bacteria (SRB) in their respective bioreactors, the characteristics of microbial communities in attached and suspended growth biomass in the bioreactors were analyzed by high-throughput sequencing during the steady operational process. Qualitative energy dispersive spectroscopy (EDS) analysis of the precipitates from sulfide precipitation was performed. The results revealed that the precipitates as sulfide zinc were confirmed by the EDS spectrum with strong peaks of zinc and sulfur.

关键词： Membrane fouling   Membrane bioreactor   Extracellular polymeric substances   Gel layer   Thermodynamic mechanism  

摘要： In this study, fouling propensities of loosely bound extracellular polymeric substances (LB-EPSs) and tightly bound EPSs (TB-EPSs) in a membrane bioreactor (MBR) were investigated. It was found that, both the LB-EPSs and TB-EPSs possessed rather high specific filtration resistance (SFR), and LB-EPSs possessed about three times higher SFR but a lower adhesion ability than the TB-EPSs. A series of characterizations demonstrated that LB-EPSs had higher ratio of proteins to polysaccharides (PN/PS ratio), lower C=O bonds content, higher hydrophilicity, higher deformation or mixing ability and more abundant high molecular weight (MW) substances than TB-EPSs. Thermodynamic analyzes revealed that the total interaction energy between the TB-EPSs and membrane was always attractive and strengthened, well explaining the higher adhesion ability of the TB-EPSs than the LB-EPSs. Meanwhile, the filtration process was found to be associated with gel layer formation, and the high SFR of EPSs was caused by the chemical potential change in gel layer filtration. According to the Flory-Huggins lattice theory, LB-EPSs tended to form a gel layer with higher cross-linking and/or polymer entanglement level because they contained more abundant high molecular weight (MW) substance, corresponding to higher SFR than that of the TB-EPSs. The proposed thermodynamic mechanisms well interpreted the different fouling propensities of LB-EPSs and TB-EPSs in MBRs. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： Waste gas treatment   Suspended-growth bioreactor   Biofilter   Microbial population   O-Xylene conversion  

摘要： Two bioreactors, suspended-growth bioreactors (SPB) and biofilter (BF), were compared for the performances in removing gaseous o-xylene. Their efficiencies were investigated by varying the o-xylene loadings, gas flow rates, and gas-water ratios. High-throughput techniques were applied for the microbial populations assay. The conversion rate of carbon in o-xylene was calculated, and the relationship between biomass and removal efficiencies was also analyzed. Results indicated that both the SPB and BF could effectively treat gases containing o-xylene. The average removal efficiencies were 91.8% and 93.5%, respectively. The elimination capacity of the BF was much higher than that of the SPB when the intake load was below 150 g m(-3) h(-1). When the o-xylene loadings were over 150 g m(-)(3) h(-1), both the SPB and BF achieved similar o-xylene removal rates. The maximum elimination capacities were 28.36 g m(-3) h(-1) for the SPB and 30.67 g m(-3) h(-1) for BF. The SPB was more sensitive to the changes in the gas flow rate. Results of microbial assay indicated that bacteria e.g. Mycobacterium sp. and Rhodanobacter sp. might play important roles in removing o-xylene in the SPB, while the bacteria Pseudomonas sp., Sphingomonas sp., and Defluyiicoccus sp., and the fungi Aspergillus sp. and Scedosporium sp., were the o-xylene degraders in the BF. The successful application of the integrated bioreactor in treating gases containing o-xylene exhausted from the electroplating plant indicated that the integration of SPB and BF could be an effective method for removing VOCs with Henry coefficient in the range of 0.01-1.

关键词： stirred tank bioreactor   mass transfer coefficient   Escherichia coli   gas-liquid system   dimensional analysis  

摘要： With the rapid growth of pharmaceutical and biotechnology industry, stirred tank bioreactors have received much attention due to simple design, easy control of operating conditions, and low operating cost. In the development of commercial processes, however, a transition from laboratory to industrial scale faces great challenges because many properties related to size change nonlinearly as a system increases. In this context, along with an understanding of fluid dynamics, application of an efficient method for scale-up is critical for designing successful industrial process. Particularly in cell cultivation processes, it is important to evaluate the oxygen transfer and viscous properties of liquid medium. In the present study, the effect of various key operating variables such as agitation rate and aeration rate, impeller diameter, and bioreactor working volume for different impellers on the volumetric mass transfer coefficient (k(L)a) have been investigated in a stirred tank bioreactor for cultivating Escherichia coli BL21. It was found that the k(L)a tends to increase with the operating variables except the bioreactor working volume. Among the tested impellers, the pitched blade was observed to be most promising because of relatively higher k(L)a but less shear force owing to its low power number. It was also found that the liquid medium with E. coli behaves as a Newtonian liquid. Compared to conventional designs of Rushton turbines, dislocated Rushton turbine was found to deliver higher k(L)a. Finally, using dimensional analysis, the k(L)a for different impeller configurations was correlated in the form of dimensionless groups, suggesting that this approach can be used for predicting k(L)a in different scales of stirred tank bioreactors.

关键词： bioreactor   carob extract medium   ethanol fermentation   modeling   suspended cells  

摘要： In this study, various functions were evaluated and utilized to forecast observed values and kinetic parameters of the batch ethanol fabrication from carob extract in the suspended-cell stirred tank reactor (SCSTR). The best model was detected with the model comparison parameters (root-mean-square-error [RMSE], mean-absolute-error [MAE], andR(2)). The results indicated that the model Stannard (ST) successfully predicted biomass production data (RMSE = 0.26 g L-1, MAE = 0.18 g L-1, andR(2)= 0.9910), ethanol fabrication data (RMSE = 2.44 g L-1, MAE = 1.88 g L-1, andR(2)= 0.9809), and sugar depletion data (RMSE = 2.82 g L-1, MAE = 2.17 g L(-1)andR(2)= 0.9938). Nevertheless, the lowest value of the objective function (phi-factor) was also yielded as 0.041 using the model ST. Additionally, in the estimation of the kinetic data, the model ST also gave well-directed results. Besides, when an independent set of the observed values was utilized to confirm the mathematical functions, the satisfactory consequences were achieved in terms of both the experimental and kinetic values. Consequently, the model ST can work as a universal function in predicting observed values and kinetics of batch ethanol generation from carob extract in an SCSTR.

关键词： Codon optimization   Fed-batch fermentation   Lignin peroxidase   Pichia pastoris   Lignin polymerization   Technical lignin  

摘要： Lignin peroxidase (LiP) is a well-recognized enzyme for its ability to oxidize lignins, but its commercial availability is limited, which hinders the biotechnological application of LiP-based bioprocesses in lignocellulose biorefineries. This study evaluated a combination strategy to improve the expression of LiP to promote its practical use. The strategy included optimization of the lipH8 gene of Phanerochaete chrysosporium according to the codon usage of Pichia pastoris, followed by fed-batch fermentation using a 14 L bioreactor (10 L working volume). The combination strategy achieved a maximum volumetric LiPH8 activity of 4480 U L-1, protein concentration of 417 mg L-1 and a specific activity of 10.7 U mg(-1), which was higher than previous reports. Biochemical characterization showed that the recombinant LiPH8 (rLiPH8) was optimum at pH 3.0, 25 degrees C and 0.4 mM H2O2. Using the optimized conditions, rLiPH8 was used to treat isolated technical lignins namely sodaanthraquinone (SAQ) lignin and steam explosion (S-E) lignin. High-performance gel permeation chromatography (HP-GPC) analysis showed that the molecular weight (Mw) of SAQ and S-E lignins were increased by 1.43-and 1.14-fold, respectively, after the enzymatic treatment. Thermogravimetric analysis (TGA) also showed that the thermal stability of the lignins was improved, indicating that the enzyme treatment of lignins with rLiPH8 resulted in lignin re-polymerization. As the first report on rLiPH8 production using P. pastoris, this study has shed light on the possible route for the enhancement of rLiPH8 production and its potential application for upgrading technical lignins.

关键词： Cardiovascular   Small diameter   Tissue engineering   Bioreactor   Grafts   Veins  

摘要： Cardiovascular diseases are a leading cause of death. Vascular surgery is mainly used to solve this problem. However, the generation of a functional and suitable substitute for small diameter (< 6 mm) displacement is challengeable. Moreover, synthetic prostheses, made of polyethylene terephthalate and extended polytetrafluoroethylene show have shown insufficient performance. Therefore, the challenges dominating the use of autografts have prevented their efficient use. Tissue engineering is highlighted in regenerative medicine perhaps in aiming to address the issue of end-stage organ failure. While organs and complex tissues require the vascular supply to support the graft survival and render the bioartificial organ role, vascular tissue engineering has shown to be a hopeful method for cell implantation by the production of tissues in vitro. Bioreactors are a salient point in vascular tissue engineering due to the capability for reproducible and controlled variations showing a new horizon in blood vessel substitution. This review strives to display the overview of current concepts in the development of small-diameter by using bioreactors. In this work, we show a critical look at different factors for developing small-diameter and give suggestions for future studies.

关键词： L-Zagreb   Mumps   MRC-5 cells   Vero cells   CQA   Parallel Plate Bioreactor  

摘要： Leningrad-Zagreb strain of mumps vaccine virus was grown on two different cell substrates viz. MRC-5 cells and Vero cells besides its original cell substrate i.e. Chicken Embryo Cells. Homogeneous virus pools prepared from each set of experiments were then lyophilized as per standard in-house protocol. Critical Quality Attributes (CQAs) such as the titer of the bulk vaccine and potency and stability of the lyophilized vaccine were then estimated using the CCID50 method to understand the lyophilization losses and thermal losses respectively in the vaccine. Another CQA viz. the genetic homogeneity of the vaccine was also tested using the single base extension method for identifying the nucleotides present at the three known locations of single nucleotide polymorphism (SNP). Comparison of CQA results across different cell substrates indicated encouraging results for Vero cell grown L-Zagreb virus compared to the MRC-5 cells grown L-Zagreb mumps virus. Significant improvement in productivity was also observed in the dynamic culture conditions compared to the static culture conditions. Progressive work in this research area can lead to development of a cGMP manufacturing process for mumps vaccine with easy scale up potential in future.

关键词： Fixed Bed   Downstream   Cellulolytic Enzymes   Bioethanol   Biorefineries  

摘要： Cellulases are enzymes required for the production of second-generation ethanol (E2G) via biochemical route. The current paper reports the development of an apparatus for solid-liquid extraction of cellulases from solid-state fermentation (SSF) carried out in a packed bed bioreactor (PBB), operated as batch and as semicontinuous. The case study was the cultivation ofMyceliophthora thermophilaI-1D3b on sugarcane bagasse (SCB) and wheat bran (WB) (7: 3 w/w). The current work integrates the PBB to the first downstream step for recovering the enzymes produced by SSF. The substrate was inoculated and packed into the modules that composed the PBB. The fermentation occurred at 45 degrees C and air was supplied with flow rate of 350 L/h. At the end of the cultivations, each module was placed in an extraction column, a dynamic closed system in which distilled water was circulated and made to percolate the cultivated material. Variables tested were volume of water per mass of substrate, water flow rate and time of percolation. Higher contact time (120 min) and higher flow rate (2.4m(3)/h) allowed us to recover up to 85% of total enzyme activity by percolation. Lower volume (20mL/g) provides higher titer extract. The apparatus showed to be promising for SSF downstream, mainly for semicontinuous operation of PPBs.