Micro-capillary bioreactors (1 mm ID, 10 cm long) were investigated for the biodegradation of toluene vapors as a model volatile organic compound (VOC). The intended application is the removal of ...VOCs from indoor air, when such microbioreactor is coupled with a microconcentrator that intermittently delivers high concentrations of VOCs to the bioreactor for effective treatment. The effects of key operating conditions were investigated. Specifically, gas film and liquid film mass transfer coefficients were determined for different gas and liquid velocities. Both mass transfer coefficients increased with gas or liquid velocity, respectively, and the overall gas-liquid mass transfer was dominated by the liquid-side resistance. Experiments with the microbioreactors focused on the effects of gas velocity, liquid velocity and mineral medium renewal rate on the treatment of toluene vapors at different inlet concentrations. The best performance in terms of toluene removal and mineralization to CO2 was obtained when the gas and liquid velocity ratio was close to one and achieving Taylor or slug flow pattern. Sustained treatment over extended periods of time with toluene elimination capacities ranging from 4000 to over 9000 g m−3 h−1 were obtained, which is orders of magnitude greater than conventional biofilters and biotrickling filters. Biological limitations generally played a more important role than mass transfer limitation. Continuous mineral medium supply at a high rate (10 h liquid retention time) enabled pH control and provided ample nutrient supply and therefore resulted in better toluene elimination and mineralization. Overall, these studies helped select the most suitable conditions for high performance and sustained operation.
Display omitted
•The operating conditions of microbioreactors degrading VOC vapor were characterized.•Liquid and gas velocity, VOC concentration and medium renewal were optimized.•Very high rates of toluene elimination were obtained (>4000 g m−3 h−1).•PH control and fast growing suspended bacteria was key to high performance.
Polycyclic aromatic hydrocarbons (PAHs) are pollutants of critical environmental and public health concern and their elimination from contaminated sites is significant for the environment. ...Biodegradation studies have demonstrated the ability of bacteria in biofilm conformation to enhance the biodegradation of pollutants. In this study, we used our newly developed microfluidic platform to explore biofilm development, properties, and applications of fluid flow, as a new technique for screening PAHs-degrading biofilms. The optimization and evaluation of the flow condition in the microchannels were performed through computational fluid dynamics (CFD). The formation of biofilms by PAHs-degrading bacteria Pseudomonas sp. P26 and Gordonia sp. H19, as pure cultures and co-culture, was obtained in the developed microchips. The removal efficiencies of acenaphthene, fluoranthene and pyrene were determined by HPLC. All the biofilms formed in the microchips removed all tested PAHs, with the higher removal percentages observed with the Pseudomonas sp. P26 biofilm (57.4% of acenaphthene, 40.9% of fluoranthene, and 28.9% of pyrene). Pseudomonas sp. P26 biofilm removed these compounds more efficiently than planktonic cultures. This work proved that the conformation of biofilms enhances the removal rate. It also provided a new tool to rapid and low-cost screen for effective pollutant-degrading biofilms.
Display omitted
•A microfluidic device was developed to grow biofilms of Pseudomonas and Gordonia.•The microfluidic system was constructed based on computational fluid dynamics.•The microchip enables to screen PAHs' degrading capability at continuous flow.•Continuous flow and high shear stress in the microchip enhance biofilms formation.•Pseudomonas sp. P26 biofilm in the microdevice shows the highest PAHs removal.
cell culture models are emerging as promising tools to understand human development, disease progression, and provide reliable, rapid and cost-effective results for drug discovery and screening. In ...recent years, an increasing number of
models with complex organization and controlled microenvironment have been developed to mimic the
organ structure and function. The invention of organoids, self-organized organ-like cell aggregates that originate from multipotent stem cells, has allowed a whole new level of biomimicry to be achieved. Microfluidic organoid-on-a-chip platforms can facilitate better nutrient and gas exchange and recapitulate 3D tissue architecture and physiology. They have the potential to transform the landscape of drug development and testing. In this review, we discuss the challenges in the current organoid models and describe the recent progress in the field of organoid-on-a-chip.
Display omitted
•The use of microbioreactor improves the selectivity for obtaining FFCA.•The enzymatic oxidation in microbioreactors generated over 30 % of FFCA.•The STYFFCA was four times higher in ...microbioreactors than in batch bioreactor.•The UM indicated that the reaction takes without mass transfer limitations.
The selectivity of 5-formyl-2-furancarboxylic acid (FFCA) was studied in a batch bioreactor and microbioreactors with different internal diameters (ID). Using microbioreactors, the effect of the flow rate of the liquid and gas phase on the yield, space time yield (STYFFCA), and gas–liquid mixture velocity (UM) of the reaction was evaluated. The biooxidation in flow microbioreactors, a selectivity of 100 % for FFCA was achieved, while with the batch bioreactor at the same substrate concentration a selectivity of 6.7 % was obtained. The highest yield (30 %) with 15 mM of 5-hydroxymethylfurfural (HMF) was reached at a gas–liquid flow rate of 0.5 µL/min and the highest STYFFCA (0.07 mol m−3 min−1) was achieved at a gas–liquid flow rate of 1.5 µL/min with the microbioreactor with an ID of 0.5 mm. The UM values (0.5 to 1.6 cm min1) indicated that the reaction takes place under a kinetic regime without mass transfer limitations.
Display omitted
•Metabolic activities of microalgae and bacteria were distinguished and quantified.•A full kinetic characterization was performed under dark and light conditions.•Microalgae were the ...larger O2 consumers under dark conditions.•Bacterial O2 uptake accounted for 15 % of the O2 mass balance under light conditions.
Metabolic activities of microalgae and heterotrophic bacteria were characterized in terms of dissolved O2 uptake and production rates under dark and light conditions, assessing the contribution of both microbial groups to the O2 balance during wastewater treatment. Up to 13 kinetic and stoichiometric parameters were determined, allowing a quantitative description of the O2 production and uptake dynamics. Under dark conditions, the maximum specific O2 uptake rates for microalgae and bacteria were 14.73 ± 2.02 mgO2 gVSS−1 h−1 and 2.37 ± 1.52 mgO2 gVSS−1 h−1, respectively. Microalgae were therefore the largest O2 consumers under dark conditions, being responsible for up to 86 % of the total heterotrophic respiration. Under light conditions (photosynthetic metabolism for microalgae and heterotrophic metabolism for bacteria), microalgae supported a maximum specific O2 production rate of 13.76 ± 1.48 mgO2 gVSS-1 h-1, while bacteria supported a maximum specific O2 uptake of 2.37 ± 1.52 mgO2 gVSS-1 h-1. The oxygenation performance of the microalgal community was therefore superior to the O2 respiration of heterotrophic bacteria under light conditions. The kinetic characterization performed provides critical information about the photosynthetic oxygenation potential, microbial growth and heterotrophic O2 uptake, which is essential for design, optimization, and modeling of wastewater treatment processes.
Advanced fed-batch microbioreactors mitigate scale up risks and more closely mimic industrial cultivation practices. Recently, high throughput microscale feeding strategies have been developed which ...improve the accessibility of microscale fed-batch cultivation irrespective of experimental budget. This review explores such technologies and their role in accelerating bioprocess development. Diffusion- and enzyme-controlled feeding achieve a continuous supply of substrate while being simple and affordable. More complex feed profiles and greater process control require additional hardware. Automated liquid handling robots may be programmed to predefined feed profiles and have the sensitivity to respond to deviations in process parameters. Microfluidic technologies have been shown to facilitate both continuous and precise feeding. Holistic approaches, which integrate automated high-throughput fed-batch cultivation with strategic design of experiments and model-based optimisation, dramatically enhance process understanding whilst minimising experimental burden. The incorporation of real-time data for online optimisation of feed conditions can further refine screening. Although the technologies discussed in this review hold promise for efficient, low-risk bioprocess development, the expense and complexity of automated cultivation platforms limit their widespread application. Future attention should be directed towards the development of open-source software and reducing the exclusivity of hardware.
•Fed-batch micro bioreactors can mimic industrial processes and reduce scale-up risks.•Diffusion- and enzyme-controlled feedings provide an easy-to-setup substrate supply.•Automated liquid handling systems can respond sensitively to process deviations.•Microfluidic systems can be used for precise and continuous feeding.•Customized and advanced systems can be built by additional hardware integration.
•An analytical solution is derived for dissolved oxygen profiles in a microbioreactor.•The spatiotemporal evolution of oxygen transport in the microbioreactor is analyzed.•A nonlinear state estimator ...produces accurate estimates of the oxygen update rate.•Nonlinear model predictive control improves spatial control of dissolved oxygen.
Microbioreactors are a promising technology to accelerate biologic drug development. In aerobic cellular respiration, a potential limit to the productivity of such systems is the transport of oxygen from an external gas to the most oxygen-deficient cells, and the potential for excessive spatially localized dissolved oxygen which can result in cellular damage. This article analytically solves a mechanistic model for the spatiotemporal transport of oxygen through a gas-permeable membrane to the cells within a microbioreactor. An analytical solution to the partial differential equations for oxygen transport is derived using the finite Fourier transform method. A parameter-adaptive extended Kalman filter is shown to produce highly accurate estimates of the oxygen uptake rate of the cells, with some fluctuation in estimates of the specific cell growth rate and the specific oxygen uptake rate. The estimates are fed to a model predictive control formulation that improves the spatial control of dissolved oxygen during cell growth by more than 30% compared to a PID controller.
The main objective of our research was development of a modified poly glutamic acid (PG) films by polylysine (PL) at different PL content (0, 2, 4 and 6%) as a microbioreactor to growth and protect ...Gamma-aminobutyric acid (GABA) producing bacteria. The addition of PL groups between the PG backbones was completely corroborated using FTIR analysis. Scanning electron micrographs confirmed the high changes in the microstructure of PG films by PL. Density, thickness, moisture content, L* (lightness), b*(yellowness-blueness), WI (whiteness index), opacity, and elongation at break were increased with increasing the PL content. Whereas ΔE (Total color difference) and tensile strength were decreased, simultaneously. The change of water vapor permeability and a* (redness-greenness) value of PG-PL were independent from PL content. The PG-PL films were active packaging material against food borne pathogens (i.e. Bacillus cereus and Escherichia coli). But they had not any side effects on viability of probiotic bacterium (i.e. Lactobacillus brevis G42) after drying process. It is inferable that PG-PL is a suitable candidate for the development of edible coating and film with high antimicrobial properties against food borne pathogen without any side effect on probiotic viability.
•A functional food packaging material was developed.•A food packaging system contain microbioreactor was developed.•A simultaneous antibacterial packaging material and probiotic carrier was developed.•A transparence poly (L-glutamic) acid based material was developed.•Characterizations of poly (L-glutamic) acid-poly (l-lysine) film were investigated.
The ureolytic bacterium Sporosarcina pasteurii is commonly used for Microbial Induced Calcium Carbonate Precipitation (MICP). This process has a variety of applications in the fields of construction, ...geotechnical engineering, and environmental remediation. However, the factors influencing urease activity of S. pasteurii during cultivation are not yet fully understood. Even though there is debate over whether higher urease activity is in fact beneficial for MICP applications, knowledge about urease production can help provide ureolytic biomass more cost-effectively, reducing overall production costs. This study revisits the effect of various cultivation conditions on growth and urease activity by using an automated high-throughput microbioreactor system combined with a novel system for high-throughput urease activity quantification. This experimental set-up allows for unprecedented data density and enables new insights into urease production of S. pasteurii.
Several factors were tested, including oxygen limitation, the feeding of urea, choice of ammonium salt, the proportion of ammonium salt in the medium, and lowering the pH during cultivation; none of these had a notable impact on urease production. Only the addition of a broad spectrum of nutrients through regular feeding with highly concentrated yeast extract and glucose led to a 70 % increased specific urease activity compared to a batch culture.
These results can improve the understanding of the regulatory mechanisms governing urease expression in S. pasteurii during cultivation, and allow to adapt the cultivation process accordingly. Additionally, the new system for automated high-throughput enzyme activity determination presented in this study could be applied to optimize bioprocesses involving other ion producing enzymes.
Display omitted
•A new procedure for automated urease activity determination during cultivation is shown.•Oxygen limitation impairs growth and urease activity in Sporosarcina pasteurii.•Feeding yeast extract and glucose strongly increases the urease activity.
The development of cancer models that rectify the simplicity of monolayer or static cell cultures physiologic microenvironment and, at the same time, replicate the human system more accurately than ...animal models has been a challenge in biomedical research. Organ-on-a-chip (OoC) devices are a solution that has been explored over the last decade. The combination of microfluidics and cell culture allows the design of a dynamic microenvironment suitable for the evaluation of treatments' efficacy and effects, closer to the response observed in patients. This systematic review sums the studies from the last decade, where OoC with cancer cell cultures were used for drug screening assays. The studies were selected from three databases and analyzed following the research guidelines for systematic reviews proposed by PRISMA. In the selected studies, several types of cancer cells were evaluated, and the majority of treatments tested were standard chemotherapeutic drugs. Some studies reported higher drug resistance of the cultures on the OoC devices than on 2D cultures, which indicates the better resemblance to in vivo conditions of the former. Several studies also included the replication of the microvasculature or the combination of different cell cultures. The presence of vasculature can influence positively or negatively the drug efficacy since it contributes to a greater diffusion of the drug and also oxygen and nutrients. Co-cultures with liver cells contributed to the evaluation of the systemic toxicity of some drugs metabolites. Nevertheless, few studies used patient cells for the drug screening assays.
PDF
