Batch Conditions Research Articles

Biosynthesis and properties of polyhydroxyalkanoates synthesized from mixed C5 and C6 sugars obtained from hardwood hydrolysis

Glucose and xylose are fermentable sugars readily available from lignocellulosic biomass, and are a sustainable carbon substrate supporting industrial biotechnology. Three strains were assessed in this work – Paraburkholderia sacchari, Hydrogenophaga pseudoflava, and Bacillus megaterium – for their ability to uptake both C5 and C6 sugars contained in a hardwood hydrolysate produced via a thermomechanical pulping-based process with concomitant production of poly(3-hydroxyalkanoate) (PHA) biopolymers. In batch conditions, B. megaterium showed poor growth after 12 h, minimal uptake of xylose throughout the cultivation, and accumulated a maximum of only 25 % of the dry biomass as PHA. The other strains simultaneously utilized both sugars, although glucose uptake was faster than xylose. From hardwood hydrolysate, P. sacchari accumulated 57 % of its biomass as PHA within 24 h, whereas H. pseudoflava achieved an intracellular PHA content of 84 % by 72 h. The molecular weight of the PHA synthesized by H. pseudoflava (520.2 kDa) was higher than that of P. sacchari (265.5 kDa). When the medium was supplemented with propionic acid, the latter was rapidly consumed by both strains and incorporated as 3-hydroxyvalerate subunits into the polymer, demonstrating the potential for production of polymers with improved properties and value. H. pseudoflava incorporated 3-hydroxyvalerate subunits with at least a 3-fold higher yield, and produced polymers with higher 3-hydroxyvalerate content than P. sacchari. Overall, this work has shown that H. pseudoflava can be an excellent candidate for bioconversion of lignocellulosic sugars to PHA polymers or copolymers as part of an integrated biorefinery.

Removal of lead and copper ions from geothermal brine at various temperatures and salinities using chemically crosslinked chitosan

The control of mineral precipitation is a major challenge in several industry segments such as geothermal energy. In this study, the focus was on the prevention of lead and copper containing precipitations from geothermal fluids as frequently found at geothermal sites exploiting sedimentary basins such as from Rotliegend formations. A filter-material was applied to remove scale-forming heavy metal ions from the fluid and thus lowering the concentration of respective minerals below saturation. The filter-material was based on the cheap and abundant biopolymer chitosan and as such is easily available and environmentally harmless. The adsorption performance of lead and copper was investigated under various temperature and salinity conditions. The used synthetic solutions of the heavy metals contained also NaCl or CaCl2 as matrix electrolyte to take into account the salinity of geothermal fluids from sedimentary reservoirs. The obtained results from adsorption experiments showed that the concentration of lead and copper in the fluid could be lowered considerably in static batch tests as well as in dynamic flow-through tests over an extended time period. The adsorption rate increased towards higher temperatures when varied between 25 °C and 70 °C. However, despite chemical crosslinking the chitosan adsorption material exhibits a limited thermal stability with the adsorption performance deteriorating at elevated temperatures.

Fibrous TiO2 Alternatives for Semiconductor-Based Catalysts for Photocatalytic Water Remediation Involving Organic Contaminants.

Water decontamination remains a challenge in several developed and developing countries. Affordable and efficient approaches are needed urgently. In this scenario, heterogeneous photocatalysts appear as one of the most promising alternatives. This justifies the extensive attention that semiconductors, such as TiO2, have gained over the last decades. Several studies have evaluated their efficiency for environmental applications; however, most of these tests rely on the use of powder materials that have minimal to no applicability for large-scale applications. In this work, we investigated three fibrous TiO2 photocatalysts, TiO2 nanofibers (TNF), TiO2 on glass wool (TGW), and TiO2 in glass fiber filters (TGF). All materials have macroscopic structures that can be easily separated from solutions or that can work as fixed beds under flow conditions. We evaluated and compared their ability to bleach a surrogate dye molecule, crocin, under batch and flow conditions. Using black light (UVA/visible), our catalysts were able to bleach a minimum of 80% of the dye in batch experiments. Under continuous flow experiments, all catalysts could decrease dye absorption under shorter irradiation times: TGF, TNF, and TGW could, respectively, bleach 15, 18, and 43% of the dye with irradiation times as short as 35 s. Catalyst comparison was based on the selection of physical and chemical criteria relevant for application on water remediation. Their relative performance was ranked and applied in a radar plot. The features evaluated here had two distinct groups, chemical performance, which related to the dye degradation, and mechanical properties, which described their applicability in different systems. This comparative analysis gives insights into the selection of the right flow-compatible photocatalyst for water remediation.

Ion-exchange resin-supported palladium catalysts for hydrodehalogenation of aryl halides under batch and continuous flow conditions

Anion-exchange resin-supported palladium catalysts for dehalogenation of aromatic halides have been prepared by immobilizing Pd(II) on anion-exchange resins followed by reduction in hydrogen atmosphere. These catalysts showed high catalytic activity and selectivity in the hydrodehalogenation of various aryl halides both by hydrogen transfer from aqueous sodium formate in water–ionic liquid mixtures under batch conditions, and by hydrogenation in ethanol under moderate pressure of H2 in a continuous flow microreactor.

Chemical conditioning of drinking groundwater through Ca2+/Mg2+ ratio adjust as a treatment to reduce Ca precipitation: Batch assays and test bench experiments

Drinking groundwater sources can vary in their calcium (Ca)/magnesium (Mg) ratios, alkalinity levels, and temperatures. High levels of calcium relative to magnesium in water encourage Ca precipitation, causing pipe obstruction problems during water distribution. Ca/Mg ratio was studied in batch experiments using synthetic and real groundwater at different alkalinity levels, and temperatures to obtain an optimal condition that reduces Ca precipitation. The addition of magnesium salts to real drinking water was also investigated as a means of adjusting the Ca/Mg ratio and reducing Ca precipitation. A test bench was used to examine the effect of water velocity during its conduction on Ca precipitation, simulating an intermittent water supply. The results were analyzed and compared in terms of initial precipitation, rate of precipitation, and maximum precipitation of Ca using a modified model of Gompertz, and the precipitate was analyzed through X-ray Diffraction. The results of the present work found an optimal Ca/Mg ratio (1.1) that avoided Ca precipitation at batch conditions and during water conduction at different velocities, as well as Ca/Mg ratios that retarded or increased both the induction time and the maximum rate of Ca precipitation. Chemical conditioning by adjusting the Ca/Mg ratio is a viable option to minimize Ca precipitation in pipes.

Generalization and Evaluation of the Analytical Solution of Intraparticle Diffusion Models in Finite Batch Adsorption

AbstractIn this paper, a detailed description of particle adsorption/diffusion model in batch systems is presented. The phenomenological equations are based on a mechanism combining mass transfer by convection from bulk phase to particle surface, intraparticle mass diffusion and equilibrium adsorption processes. The change of bulk and particle concentration is modeled through differential mass balance equations, leading to a system of one ordinary differential equation and one partial differential equation. When adsorption equilibrium follows a linear relationship, this system of equations can be solved by the Laplace transform method. The purpose of this paper is the development of a generalized analytical solution, that is rewritten specifically for each of the traditional particle shapes: slab, cylinder, and sphere. Finally, this analytical solution is evaluated through several simulations in different batch conditions and compared to simulated experimental data, showing the capability of this analytical solution to predict batch adsorption processes when adsorbate concentration is low. This result clearly indicates the feasibility of applying the analytical solution presented in this paper, which is based on phenomenological concepts, to describe the adsorption kinetics of processes, when the linear isotherm can be considered adequate to represent the adsorption equilibrium.

Microorganism Carrier-Surface Method as an Efficient Model for Microscopic Characterization of Biofilm Structure and Dispersion in Dairy Associated Spore-Forming Bacteria

Dispersion, defined as the release of planktonic cells is the final stage of biofilm development and of major significance in clinical and industrial settings. Currently, biofilm dispersion is considered as a promising avenue for biofilm control and an important topic research. However, a problem facing such research projects is how to induce planktonic life in a biofilm. Numerous systems are used for the investigation of biofilm dispersion, including dynamic continuous or static batch systems. This mini-review describes the usefulness of the microorganism carrier-surface method as a simple biofilm growth model which successfully allowed microscopic characterization of biofilm structure and dispersion in dairy-associated spore-forming bacteria and should be an efficient model for studying dispersion process.

Enhanced fluoride remediation from aqueous solution by La-modified ZIF-8 hybrids

To ensure water safety, fluoride elimination from aqueous environment is an urgent affair. In this study, a series of La-modified ZIF-8 (denoted as La-ZIF-8) hybrids with different contents of La were fabricated via a solvothermal reaction and used for fluoride recovery from wastewater. The structure and morphology of the fabricated La-ZIF-8 hybrid were confirmed by various techniques (SEM, XRD, BET, FTIR, and XPS). The specific surface area along with the pore volume of La-ZIF-8 hybrid was 121 m2 g−1 and 0.816 cm3 g−1, respectively. The defluoridation performance of La-ZIF-8 under different conditions was assessed by static batch trials. The optimized La-ZIF-8 with a La/Zn molar ratio of 4:1 achieved the supreme defluoridation performance. The fluoride uptake was greatly enhanced from 1.85 mg g−1 for pure ZIF-8–49.5 mg g−1 for La-ZIF-8 at C0 = 10 mg L−1. The results revealed that La-ZIF-8 had a maximal fluoride uptake of 224.72–230.95 mg g−1 at 30–50 °C, pH 4, and C0 = 80 mg L−1. Adsorption of fluoride on La-ZIF-8 obeyed to the Langmuir isotherm (R2 > 0.99) and pseudo-second order model (R2 > 0.999), reflecting a single-layer chemical adsorption process. ΔH0 (36.38 kJ mol−1) > 0, ΔS0 (155.36 J mol−1 K−1) > 0, and ΔG0 < 0 stated that the defluoridation by La-ZIF-8 is an endothermic nature, random state, highly feasible and spontaneous process. The co-existing of cations and anions effect inferred that Mg2+, Ca2+, SO42–, Cl–, and NO3– only had a trivial impact on fluoride removal performance, illustrating the high selectivity for F–. The La-ZIF-8 can be deemed to be a candidate adsorbent for tackling F− pollution.

“In vivo biosynthesis of N,N-dimethyltryptamine, 5-MeO-N,N-dimethyltryptamine, and bufotenine in E.coli”

N,N-dimethyltryptamine (DMT), 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT) and 5-hydroxy-N,N-dimethyltryptamine (bufotenine) are psychedelic tryptamines found naturally in both plants and animals and have shown clinical potential to help treat mental disorders, such as anxiety and depression. Advances in both metabolic and genetic engineering make it possible to engineer microbes as cell factories to produce DMT and its aforementioned derivatives to meet demand for ongoing clinical study. Here, we present the development of a biosynthetic production pathway for DMT, 5-MeO-DMT, and bufotenine in the model microbe Escherichia coli. Through the application of genetic optimization techniques and process optimization in benchtop fermenters, the in vivo production of DMT in E. coli was observed. DMT production with tryptophan supplementation reached maximum titers of 74.7 ± 10.5 mg/L under fed batch conditions in a 2-L bioreactor. Additionally, we show the first reported case of de novo production of DMT (from glucose) in E. coli at a maximum titer of 14.0 mg/L and report the first example of microbial 5-MeO-DMT and bufotenine production in vivo. This work provides a starting point for further genetic and fermentation optimization studies with the goal to increase methylated tryptamine production metrics to industrially competitive levels.

Photo-induced 1,2-aryl migration of 2-chloro-1-arylpropanone under batch and flow conditions: Rapid, scalable and sustainable approach to 2-arylpropionic acids

We report the photo-mediated 1,2-aryl migration of 2‑chloro-1-arylpropanones to 2-arylpropionic acids using HCOONa as an acid scavenger. This pragmatically focused study obviates the multiple-step sequence in the industrially employed, ZnO-promoted rearrangement strategy, and offers rapid access to various 2-arylpropionic acids under environmentally friendly conditions. Furthermore, the successful transfer of this batch photochemistry to a continuous flow platform led to improved scalability and enabled the gram-scale synthesis of loxoprofen.

Kinetic modelling: Regression and validation stages, a compulsory tandem for kinetic model assessment

AbstractThe development of robust and reliable kinetic models is vital to build safe, eco‐friendly, and cost‐competitive chemical processes. Establishing kinetic models for complex chemical systems such as biomass valorization is cumbersome because the kinetic modeller must test different models and fit several experimental observables (or concentrations). Usually, in chemical reaction engineering, kinetic model assessment is based solely on the regression stage outputs. The implementation of a validation stage can aid in choosing the most reliable kinetic models, essentially in the case of complex chemical systems. We studied the solvolysis of 5‐hydroxymethylfurfural (5‐HMF) to butyl levulinate (BL) as a model reaction constituting several consecutive and parallel reaction steps. From an existing kinetic model, we created 60 synthetic runs in batch conditions. In the first part, we tested four different models with 5 degrees of noise, and we carried out the modelling on the 60 synthetic runs. In the second part, two types of holdout methods were evaluated. In the last part, cross‐validation, namely the k‐fold method, was used. We found that the 10‐fold method allowed more efficient selection results even when the noise level was high. Besides, k‐fold allows for not scarifying experimental runs and selecting the most reliable model.

PILOT-PLANT SCALE BIOMASS PRODUCTION BY LACTOBACILLUS RHAMNOSUS GG ATCC 53103: A COMPARISON BETWEEN BATCH AND FED-BATCH FERMENTATION

Probiotics such as Lactobacilli are important in improving normal intestinal flora and hindering the growth of harmful bacteria in the digestive system. Given the above reasons, the industrial production of probiotics and the use of high-yield strains is of great importance. The present study compares the biomass production by Lactobacillus rhamnosus GG ATCC 53103 in batch and fed-batch cultures conditions at a pilot plant scale. An optimized medium containing the following compounds (g/L): glucose 112.50, sugar beet molasses 56.25, casein 18.75, yeast extract 18.75, K2HPO4 13.13, Tween 80 1.88, MgSO4.7H2O 0.3750, MnSO4. 4H2O 0.0750, CaCl2. 2H2O 0.1875 and Simethicone 1.25 was used for biomass production. During the fermentation process, culture conditions such as pH, temperature, and oxygen concentration were monitored using process analytical technology (PAT). Based on the obtained results, the maximum biomass production in the batch condition in the first 20 hours of culture in the optimized medium was about 68.14 g/L. After three stages of fed-batch culture, the biomass production by L. rhamnosus GG ATCC 53103 reached 93.5 g/L at 37°C with agitation and aeration rates of 100 rev/min and 300 VV-1min-1, respectively. Therefore, biomass production increased about 2.67-fold more than the basal medium.

Untreated Opuntia ficus indica for the Efficient Adsorption of Ni(II), Pb(II), Cu(II) and Cd(II) Ions from Water.

The raw cladode of Opuntia ficus indica (OFI) was evaluated as a sustainable biosorbent for the removal of heavy metals (Ni, Pb, Cu, and Cd) from aqueous solutions. The functional groups of OFI were identified by employing DRIFT-FTIR and CP-MAS-NMR techniques before and after contact with the ions in an aqueous media, showing a rearrangement of the biomass structure due to the complexation between the metal and the functional groups. The adsorption process was studied in both single- and multi-component systems under batch conditions at different pHs (4.0, 5.0, and 6.0), different metal concentrations, and different biomass amounts. The results show that the raw OFI had a removal capacity at room temperature of over 80% for all metals studied after only 30 min of contact time, indicating a rapid adsorption process. Biosorption kinetics were successfully fitted by the pseudo-second-order equation, while Freundlich correctly modelled the biosorption data at equilibrium. The results of this work highlight the potential use of the untreated cladode of OFI as an economical and environmentally friendly biosorbent for the removal of heavy metals from the contaminated aqueous solution.

C3-Alkylation of furfural derivatives by continuous flow homogeneous catalysis.

The C3-functionalization of furfural using homogeneous ruthenium catalysts requires the preinstallation of an ortho-directing imine group, as well as high temperatures, which did not allow scaling up, at least under batch conditions. In order to design a safer process, we set out to develop a continuous flow process specifically for the C3-alkylation of furfural (Murai reaction). The transposition of a batch process to a continuous flow process is often costly in terms of time and reagents. Therefore, we chose to proceed in two steps: the reaction conditions were first optimized using a laboratory-built pulsed-flow system to save reagents. The optimized conditions in this pulsed-flow mode were then successfully transferred to a continuous flow reactor. In addition, the versatility of this continuous flow device allowed both steps of the reaction to be carried out, namely the formation of the imine directing group and the C3-functionalization with some vinylsilanes and norbonene.

Investigation of petroleum products dehydration using natural zeolite and activated carbon

This novel research presents an investigation on petroleum products dehydration using the adsorption method by low-cost adsorbents. To investigate the performance of proposed process intended to separate emulsified water, synthetic stabilized water emulsions in different petroleum products (Gasoline, Kerosene, and Gas oil) which equal 300, 600, and 800 ppm were prepared. Afterwards, under batch conditions, natural zeolite and activated carbon as economic adsorbents were utilized for the dehydration process. The characteristics of adsorbent was examined using SEM and XRD analysis. The obtained results from BET analysis also depicted that the specific surface area of activated carbon was considerably more than that of zeolite. Results showed that both zeolites and activated carbon can effectively purify petroleum products from undesirable emulsified water. The comparison of the adsorbents’ efficiency indicated that activated carbon has a higher affinity than zeolite for water in gasoline and gas oil, however, they had almost the same adsorption capacity in kerosene dehydration. The maximum water removal percentage of gas oil, kerosene and gasoline using zeolite was 84.84, 92.17, and 88.64, respectively. Dehydration by activated carbon also led to 86.44, 93.43 and 90.2 per cent water removal from gas oil, kerosene and gasoline, respectively.

Development of Silicon Nanowire Array–Metal Hybrid Catalysts for Batch and Flow Organic Reactions

AbstractThe development of highly efficient and reusable supported metal catalysts is important for academic and industrial synthetic organic chemistry; however, their widespread application remains a challenge because supported Pd, Rh, and Pt catalysts are expensive. To overcome these problems, we have developed novel, highly stable, reusable, and selective heterogeneous catalysts consisting of silicon nanowire arrays (SiNAs) and metal nanoparticle composites. Metal nanoparticles on SiNA have been applied as heterogeneous catalysts in the Mizoroki–Heck reaction, C–H arylation, hydrosilylation, hydrogenation, reductive alkylation of amines, and hydrogenative decarboxylation of fatty acids. The catalysts used in this study showed high catalytic activity in batch and microflow conditions. Their structural investigation using X-ray Photoelectron Spectroscopy (XPS) suggests that strong metallic bonding (alloy/agglomeration) between the metal and silicon (metal silicide bond formation) is key to the high catalyst stability.1 Introduction2 Development of Silicon Nanowire Array (SiNA) Hybrid Catalysts and Silicon Nanostructure (SiNS) Hybrid Catalysts3 Application of SiNA-Pd to Organic Synthesis4 SINA-Supported Mono- and Bimetallic Nanoparticles for Hydrogenation Reactions5 Application of SiNA-Pd to Microflow Reductive Alkylation Reactions6 Application of SiNA-Rh to Hydrogenative Decarboxylation Reactions using Microwave Irradiation7 Conclusions

Synthesis of an IRMOF-1@SiO2 Core-Shell and Amino-Functionalization with APTES for the Adsorption of Urea and Creatinine Using a Fixed-Bed Column Study.

Kidney dysfunction is a clinical disease that disables the kidneys to remove the waste products and uremic toxins from the circulation and may lead to fatal kidney failure. Hemodialysis is advantageous in this circumstance since it prevents the accumulation of waste products in the body and facilitates the removal of uremic toxins. However, hemodialysis cannot entirely remove some uremic toxins, such as urea and creatinine. In this paper, a high-performance fixed-bed column for urea and creatinine removal was offered. As a result, a MOF layer was built on SiO2, which was then amino-functionalized using APTES. Numerous assays were used to characterize the final adsorbent. The adsorption of urea and creatinine was evaluated in batch and continuous conditions. Thus, it was demonstrated that the adsorption behavior of A(0.2)-IRMOF-1@SiO2 followed the Langmuir isotherm, and it exhibited the maximum adsorption capacity. The batch experiment determined that urea and creatinine had an adsorption capacity of 1325.73 and 625.00 mg·g-1, respectively. The adsorption capacity was increased, which was due to the presence of amino groups (APTES) on the MOF surface. The continuous operation was evaluated using the A(0.2)-IRMOF-1@SiO2 fixed-bed column. Thomas and Nelson's models were examined to achieve a better understanding of the adsorption behaviors. The A(0.2)-IRMOF-1@SiO2 fixed-bed column successfully removed 92.57% of urea and 80.47% of creatinine. The separation factor for urea in comparison to creatinine was 2.40 in the A(0.2)-IRMOF-1@SiO2 fixed-bed column.

CO2-H2O assisted co-pyrolysis of petroleum vacuum residue and polypropylene to improve asphaltene reduction and coke suppression: A statistical approach

Non-catalytic co-pyrolysis of petroleum vacuum residue (VR) and polypropylene (PP) was studied under CO2 and/or steam atmospheres in a batch condition. A statistical approach was performed to analyze the effect of temperature, CO2 initial pressure, reaction time, PP and water contents using fractional factorial design methodology. A comparison of co-pyrolysis in steam, CO2, and steam + CO2 atmospheres showed that CO2 + steam is a more effective environment for reduction of asphaltene and suppressing coke formation. In detail, steam dominated the pyrolysis process, whereas CO2 enhanced the thermal cracking reactions, thereby increasing the asphaltene conversion to maltene and decreasing coke formation. Moreover, the results indicated that the addition of PP to VR improved the yield and quality of the liquid product and diminished the coke content. The optimum conditions were the temperature of 380 °C, CO2 initial pressure of 0.6 MPa, reaction time of 90 min with PP/ VR and water/ VR ratios of 0.23, and 0.25 (g/g), respectively. Pyrolysis of VR under such conditions resulted in the 86% maltene yield, 89.7% asphaltene reduction and 6.3% coke reduction. 1H NMR analysis showed that paraffins occupy the major content of the liquid (81.07 vol%), followed by aromatics (12.28 vol%) and olefinic compounds (6.65 vol%). In addition, the upgraded oil had a remarkable °API gravity of 35.9 and a low viscosity of 5.27 ± 0.02 cP. Furthermore, heavy metals of Ni and V were removed from the liquid product by 56.1% and 65.6%, respectively. Pyrolysis of VR with PP in the CO2 + steam environment would be deemed an economically viable and environmentally friendly technique of transforming the abundant low-grade VR feedstocks to valuable liquid fuels at a milder processing condition without using any catalysts.

Elution of the residual water-soluble ammonium from the weathered crust elution-deposited rare earth tailings: Kinetics and mechanism

The water-soluble ammonium (WS-A) in the weathered crust elution-deposited rare earth tailings is adsorbed on the clay mineral surface through weak forces (van der Waals forces and hydrogen bonds), and it is easy to migrate with rainwater, causing serious environmental pollution. Therefore, the study of the elution process of water-soluble ammonium is critical for the remedy of rare earth tailings leached with ammonium. This work aims to investigate the elution process and mechanism of the WS-A from the tailings and determine the optimum elution conditions. Effects of the factors on the removal efficiencies of WS-A were studied under batch and dynamic conditions. Results illustrated that the elution of WS-A is particle size, liquid–solid ratio, pH, ion strength, and temperature dependent, and it was easy to be eluted at weak acid conditions, high liquid–solid ratio, and high temperature from the tailings with small particle size. Moreover, WS-A elution is a fast process controlled by both external and internal diffusion, and a high elution efficiency of 99.98% could be reached under the optimum dynamic conditions. FTIR and XPS showed that nitrogen content was decreased obviously after elution by water, and the concentration gradient diffusion was the main driving force for the elution of WS-A absorbed on illite, halloysite, and kaolinite at different interaction sites. This study had great significance in reducing the environmental contamination caused by residual water-soluble ammonium after the in-situ elution of weathered crust elution-deposited rare earth ore.

Microbioreactors for nutrient-controlled microbial cultures: Bridging the gap between bioprocess development and industrial use.

It is common practice in the development of bioprocesses to genetically modify a microorganism and study a large number of resulting mutants in order to select the ones that perform best for use at the industrial scale. At industrial scale, strict nutrient-controlled growth conditions are imposed to control the metabolic activity and growth rate of the microorganism, thereby enhancing the expression of the product of interest. Although it is known that microorganisms that perform best under these strictly controlled conditions are not the same as the ones that perform best under uncontrolled batch conditions, screening, and selection is predominantly performed under batch conditions. Tools that afford high throughput on the one hand and dynamic control over cultivation conditions on the other hand are not yet available. Microbioreactors offer the potential to address this problem, resolving the gap between bioprocess development and industrial scale use. In this review, we highlight the current state-of-the-art of microbioreactors that offer the potential to screen microorganisms under dynamically controlled conditions. We classify them into: (i) microtiter plate-based platforms, (ii) microfluidic chamber-based platforms, and (iii) microfluidic droplet-based platforms. We conclude this review by discussing the opportunities of nutrient-fed microbioreactors in the field of biotechnology. This article is protected by copyright. All rights reserved.