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关键词： Cattleya forbesii Lindl   Protocorm   Thin cell layer   In vitro   Temporary immersion system   Bioreactor   Mass propagation  

摘要： An efficient in vitro mass propagation through protocorm-like bodies (PLBs) was established in Cattleya forbesii Lindl., a commercially important orchid. Whole PLBs (W-PLB) and transverse thin cell layers of PLB (tTCL-PLB) explants were cultured in RITA((R)) bioreactors based on temporary immersion system. Explants were transferred in semi-solid or RITA((R)) bioreactor for protocorm production or shoot regeneration. The effect of different immersion frequencies, medium volumes and inoculum densities were studied and optimized. RITA((R)) bioreactor cultures were found to be superior compared with semi-solid cultures regarding PLB production and shoot regeneration. tTCL-PLB explant types cultured in the RITA((R)) bioreactor with immersion for 1min/4h, 250mL of medium and 20 explants showed the highest number of PLBs per RITA((R)) (2237 PLBs) and per explant (111.9 PLBs). The highest number of PLBs per explant was 21 times higher than those from semi-solid culture. The highest number of shoots per RITA((R)) (3998 shoots) and per explant (199.9 shoots) were observed on tTCL-PLB cultured in RITA((R)) bioreactor (1min/4h;150mL of medium and 20 explants). The highest number of shoots per explant was 95 times higher than those grown on semi-solid culture. Mass propagation of PLBs and shoots of C. forbesii Lindl. using combined thin cell layer and RITA((R)) temporary immersion has been adapted in commercial practice.

关键词： Multi-objective optimization   Robustness   Sigma point method   Uncertainty propagation  

摘要： Model-based optimization techniques play a key role in achieving a sustainable operation of biochemical processes. Models are an approximation of the real process under study, hence, uncertainty is inherently present and for a sustainable process operation this uncertainty should be accounted for. In practice, optimality with respect to different conflicting objectives is required and multi-objective optimization is a valuable tool. In this article the sigma point approach is applied to account for parametric uncertainty in the frame of interactive multi-objective bioprocess optimization.

关键词： aerobic granular sludge   extracellular polymeric substance   membrane bioreactor   membrane fouling   municipal sewage  

摘要： The aerobic granular sludge membrane bioreactor (AGS-MBR) has the potential for simultaneous carbon/nitrogen removal and membrane fouling mitigation. Most studies have focused on comparison of granular sludge MBR and flocculent sludge MBR in short-term tests using synthetic wastewater. In this study, two identical AGS-MBRs were developed, and the reactor performance and membrane fouling were examined systemically over 120 days for synthetic wastewater and municipal sewage treatment, respectively. Results showed that regular granules with good settling ability were developed and maintained throughout the experimental period. Regardless of the substrate type, AGS-MBR demonstrated a stable removal of carbon (85-95%) and nitrogen (50-55%) in long-term operation. In addition, the membrane fouling propensity is apparently lower in AGS-MBRs with no membrane cleaning for 4 months at a flux of 20 L m(-2) h(-1). The filtration resistance analysis indicates that the main membrane resistance was caused by irreversible fouling in both of the reactors. Membrane foulant analysis indicates that proteins in extracellular polymeric substances are more prone to be attached by the membrane of AGS-MBRs because of their hydrophobic nature. This study shows that AGS-MBR is effective and stable for municipal sewage treatment and reuse during long-term operation.

关键词： stirred tank bioreactor   mass transfer coefficient   response surface methodology   Box-Behnken design   gas-liquid system  

摘要： Stirred tank reactors are most commonly used both in the laboratory and industry. Particularly for bioreactors, the volumetric mass transfer coefficient (k(L)a) of oxygen is used as one of the important parameters for determining efficiencies of reactors and for successful scale-up. A number of correlation methods have been previously developed to predict the k(L)a in stirred tank bioreactors. In the present work, we propose a new correlation for k(L)a based on a mathematical and statistical approach using Response Surface Methodology (RSM) based on Box-Behnken design of experiments. This correlation includes the effect of various parameters such as impeller agitation rate (50-800 rpm), air flow rate (0.5-3.5 L/min), and temperature (10-40 degrees C) for different impeller configurations (single and dual Rushton, pitched blade, and mixed turbines). It was observed that the k(L)a increases with increasing the parameters for all the impeller configurations studied. Among the operating parameters, the most significant variable impacting k(L)a was found to be agitation rate, followed by air flow rate, and temperature. The models developed using RSM successfully interpreted the experimental k(L)a and were further validated under other operating conditions. It was also found that, compared with conventional power-law models, the RSM approach enables a more efficient correlation procedure and formulates simplified models with comparably high accuracy, suggesting that the RSM is promising for evaluation of oxygen mass transfer in stirred tank bioreactors. (c) 2018 American Institute of Chemical Engineers Environ Prog, 38: 387-401, 2019

关键词： multivariate curve resolution   fluorescence   on-line diagnostics   monitoring   bioreactor  

摘要： This study describes the application of the multivariate curve resolution (MCR) analysis technique for real-time analysis of culture fluorescence during recombinant Pichia pastoris cultivation in a bioreactor. Fluorescence spectra were acquired with an on-line dual excitation wavelength fluorometer and then used to develop a real time MCR-based bioprocess monitoring and diagnostics tool. Initial bioreactor experiments using two similar recombinant antibody secreting P. pastoris cell lines showed significant differences in protein production. To distinguish between the contributions of operating conditions and the specific cell line's genetic composition to the observed differences in protein production, the bioreactor experiments were repeated and accompanied by real time MCR analysis. The tests demonstrated high sensitivity of MCR-derived pure concentration profiles to growth as well as to initial conditions, thus enabling real-time cultivation process trend diagnostics and fault detection. (c) 2018 Her Majesty the Queen in Right of Canada (c) 2018 American Institute of Chemical Engineers Biotechnol. Prog., 35: e2761, 2019.

关键词： Bioreactors  

摘要： Denitrifying bioreactors are dependent on organic matter supply as a substrate for effective NO3 removal. In this study, the difference in removal efficiency and side effects when using different organic matter sources and dosing strategies was tested in two field experiments. The organic matter sources tested were woodchips and ethanol. The effect of woodchips was tested using woodchip-enveloped drains. Ethanol was supplied to a flow-through reactor by passive dosing by diffusion through silicone tubing. The woodchip-enveloped drains showed a removal efficiency of 80% during the first year of application, but this rate decreased during the second and third years of application, coinciding with a decrease in dissolved organic C and an increase in redox potential. The removal efficiency was higher and remained higher over a longer period of time when the drains were installed more deeply. The flow-through reactor with ethanol could lead to a higher removal efficiency (up to 95%) at higher hydraulic retention time (HRT, 0.1 d) than the woodchip-enveloped drains (HRT = 5 d). Passive dosing of organic substrates is simple, needs little maintenance and no energy, and can be performed independent of electricity. A denitrifying bioreactor with a controlled drainage inlet and outlet is a promising setup for optimizing N removal and minimizing side effects.

关键词： Raman spectroscopy   process analytical technology (PAT)   design of experiment   Chinese hamster ovary cultures (CHO cultures)   control  

摘要： The biopharmaceutical industry is moving toward a more quality by design (QbD) approach that seeks to increase product and process understanding and process control. Miniature bioreactor systems offer a high-throughput method enabling the assessment of numerous process variables in a controlled environment. However, the number of off/at-line samples that can be taken is restricted due to the small working volume of each vessel. This limitation may be resolved through the use of Raman spectroscopy due to its ability to obtain multianalyte data from small sample volumes fast. It can, however, be challenging to implement this technique for this application due to the complexity of the sample matrix and that analytes are often present in low concentration. Here, we present a design of experiments (DOE) approach to generate samples for calibrating robust multivariate predictive models measuring glucose, lactate, ammonium, viable cell concentration (VCC) and product concentration, for unclarified cell culture that improves the daily monitoring of each miniature bioreactor vessel. Furthermore, we demonstrate how the output of the glucose and VCC models can be used to control the glucose and main nutrient feed rate within miniature bioreactor cultures to within qualified critical limits set for larger scale vessels. The DOE approach used to generate the calibration sample set is shown to result in models more robust to process changes than by simply using samples taken from the typical process. (c) 2018 American Institute of Chemical Engineers Biotechnol. Prog., 35: e2740, 2019.

关键词： Nitrification   MBBR   TF   Biofilm morphology   EPS   Microbial community  

摘要： Mariculture wastewater treatment by nitrification requires a long start-up time due to high salinity stress. This study aimed to verify the faster start-up of a trickling filter (TF) compared to a moving bed bioreactor (MBBR) treating synthetic mariculture wastewater, and to investigate the feasibility of transferring mature biocarriers from the TF to a new MBBR (TF-MBBR). The nitrogen removal performance, biofilm physicochemical properties and microbial communities were investigated. The results obtained showed that, the TF started up 41 days faster than the MBBR, despite the richer microbial diversity in the latter. Lower biofilm roughness and protein content as well as higher adhesive force and polysaccharide content in the TF were obtained compared to the MBBR. Adhesive force was found to be negatively correlated with roughness (r = -0.630, p = 0.069). Transmittance assigned to amide II (1538 cm(-1)) and amid III (1243 cm(-1)) through Fourier transform infrared spectroscopy (FTIR) determination was only obtained in the TF, which was likely related to the faster start-up. Nitrosomonas and Nitrospira were detected as the predominant nitrifiers in both reactors. In addition, the new MBBR, incubated with the mature biocarriers transferred from the TF, had a satisfactory nitrification performance with no lag time. Interestingly, the transfer action increased the microbial diversity and made the biofilm physicochemical characteristics shift toward those of the MBBR. Taken together, the study confirmed that MBBR nitrification start-up can be accelerated via TF and biocarrier transfer. (C) 2018 Elsevier Ltd. All rights reserved .

关键词： Staphylococcus aureus   bioreactor culture   daptomycin   whole-genome sequencing analysis   evolution of resistance  

摘要： The extensive use of daptomycin for treating complex methicillin-resistant Staphylococcus aureus infections has led to the emergence of daptomycin-resistant strains. Although genomic studies have identified mutations associated with daptomycin resistance, they have not necessarily provided insight into the evolution and hierarchy of genetic changes that confer resistance, particularly as antibiotic concentrations are increased. Additionally, plate-dependent in vitro analyses that passage bacteria in the presence of antibiotics can induce selective pressures unrelated to antibiotic exposure. We established a continuous culture bioreactor model that exposes S. aureus strain N315 to increasing concentrations of daptomycin without the confounding effects of nutritional depletion to further understand the evolution of drug resistance and validate the bioreactor as a method that produces clinically relevant results. Samples were collected every 24 h for a period of 14 days and minimum inhibitory concentrations were determined to monitor the acquisition of daptomycin resistance. The collected samples were then subjected to whole genome sequencing. The development of daptomycin resistance in N315 was associated with previously identified mutations in genes coding for proteins that alter cell membrane charge and composition. Although genes involved in metabolic functions were also targets of mutation, the common route to resistance relied on a combination of mutations at a few key loci. Tracking the frequency of each mutation throughout the experiment revealed that mutations need not arise progressively in response to increasing antibiotic concentrations and that most mutations were present at low levels within populations earlier than would be recorded based on single-nucleotide polymorphism (SNP) filtering criteria. In contrast, a serial-passaged population showed only one mutation in a gene associated with resistance and provided limited detail on the changes that occur u

关键词： Antibiotic resistance genes   Membrane bioreactor   Separation coefficient   Log removal value   Canonical correlation analysis  

摘要： Antibiotic resistance genes (ARGs) discharged through wastewater treatment plants (WWTPs) has aroused growing public concern for its risk to human health and ecological safety. Membrane bioreactor (MBR) has been recognized as an effective approach to remove ARGs in full-scale WWTPs, but its advantage over traditional processes was not clearly quantified. To address this, we investigated four full-scale WWTPs containing parallel MBR and traditional processes (oxidation ditch or sequencing batch reactor) to compare the reduction of eight types of ARGs (bla(TEM), ermB, tetW, tetO, sul1, sul2, addD, and qnrS) and int1. In general, MBRs reduced the ARGs (1.1-7.3 log removal) better than parallel processes (0.4-4.2 log removal). Notably, the dominant ARGs in the influent, such as ermB, sul1 and int1 (106.39-107.79 copies/mL), were more effectively reduced by MBRs (1.5-7.3 log removal) than traditional processes (0.8-3.4 log removal). Meanwhile, the distribution of those ARGs in activated sludge was not significantly different between aforementioned processes (p > 0.05). The separation coefficient (K-sw) was proposed to represent the contribution of solid separation on ARG removal, subsequent analysis revealed surprisingly strong correlation between Ksw values of dominant ARGs (ermB, sul1 and int1) and their log removal by MBR (R = 0.79-0.96, p < 0.05), while such correlation was much weaker in traditional process (R = 0.33-0.37), indicating solid separation was the major pathway for removal of dominant ARGs and int1. According to the canonical correlation analysis between process operation and ARG removal in MBR, sludge retention time (SRT) seemed to be the major factor affecting removal of dominant ARGs and int1. This comparative study can be helpful for further understanding and operating MBR process to reduce the ARGs in effluent. (c) 2018 Published by Elsevier B.V.