Bioreactor Design Research Articles

The Potential of Public–Private Partnerships for the Bioeconomy

GEN BiotechnologyVol. 2, No. 3 EditorialFree AccessThe Potential of Public–Private Partnerships for the BioeconomyHana El-SamadHana El-SamadE-mail Address: helsamad@altoslabs.comEditor-in-Chief, GEN Biotechnology.Search for more papers by this authorPublished Online:19 Jun 2023https://doi.org/10.1089/genbio.2023.29097.editorialAboutSectionsPDF/EPUB Permissions & CitationsPermissionsDownload CitationsTrack CitationsAdd to favorites Back To Publication ShareShare onFacebookTwitterLinked InRedditEmail Eric Schmidt, the former CEO of Google, is betting on an imminent $1-trillion bioeconomy, with the potential of growing to multiple trillions in the next 10–20 years. Last year, a task force on synthetic biology and the bioeconomy, commissioned by Schmidt Futures, produced a remarkably detailed and actionable report, with five strategic areas and many recommendations to deliver a resilient and competitive bioeconomy.1 The recommendations ranged from growing a diverse talent pool to building a national infrastructure for bioproduction scale-up capacity, to changing regulatory funding and practices, and to modernizing data sharing infrastructures.In an interview with Forbes in May 2023, Schmidt augmented this list with some additional elements.2 First, he commented on his excitement about “the prospects for AI to accelerate many sectors of the bioeconomy—biomedical, agricultural, and industrial—as well as to drive new basic research discoveries in biology broadly.” He also highlighted the critical need to increase public trust in new biotechnologies by applying them responsibly and increasing confidence that these technologies will ultimately improve lives.He then reiterated the need for reformulating commercialization and regulatory processing, emphasizing “a deliberate focus on moving engineering biology discoveries from lab to market, helping new technology developers through new loan programs for biomanufacturing infrastructure, as well as through newly streamlined, clear regulatory processes.”Of particular interest was Schmidt's emphasis on the need for public–private partnerships (PPPs), using as an example BIOMADE (see below), where Schmidt Futures has made an important investment. PPPs are R&D networks that involve a range of stakeholders, including traditional academia and industry stakeholders, charities, patient organizations, and even national regulatory agencies. In the context of biomedical research, PPPs have typically been leveraged for initiatives targeting diseases that are more common in the developing world, the one notable example being Sanofi's development of fexinidazole for treating sleeping sickness.This project was a PPP, including seven European countries (France, Germany, the Netherlands, Norway, Spain, Switzerland, and the United Kingdom) as well as private foundations including the Bill & Melinda Gates Foundation and Medecins Sans Frontieres.BIOMADE is a particularly compelling initial example for a bioeconomy-focused PPP. It is a Manufacturing Innovation Institute sponsored by the U.S. Department of Defense and a member of Manufacturing USA®, a national network of public–private collaborations created to secure U.S. global leadership in advanced manufacturing. BIOMADE membership includes an impressive array of companies, universities, and national laboratories, community and technical colleges, nonprofit and K-12 education, as well as venture capital.As an example of its many activities, BIOMADE announced in April 2023 a roster of five projects (supported by Schmidt Futures) to advance bioreactor design and development. The membership of these projects includes both universities and for-profit companies. Commenting on these projects and the prospect of success of the BIOMADE model, Schmidt brings up three points that merit contemplation and discussion.First, these projects are a meaningful coinvestment, leveraging the opportunity for the total being more than the sum of its parts with enhanced capabilities compared with private-only or public-only enterprises.Second, the BIOMADE ecosystem surrounding these projects is purposefully constructed for sharing technologies created by any team with other BIOMADE members, while preserving proprietary information. This seems like a strategy tailored to promote the public's interest.Third—and this gave me reflective pause given that I am a San Francisco dweller—BIOMADE has a site in Minneapolis-St. Paul, Minnesota. This location in the nation's heartland, Schmidt argues, is “important because a thriving future bioeconomy depends on distributing production evenly across the country, not just in the known coastal hubs of biotechnology such as Boston and San Francisco.”Broad research on the topic has generated some understanding of additional benefits of PPPs, including amalgamation of unique skills, expertise, and resources of multiple players, reduced costs, and diversified risks among stakeholders, as well as increased project efficiency owing to clear timelines and goals.3,4 At the same time, PPPs, including BIOMADE, have many documented challenges.5Nonetheless, for all the reasons mentioned above, it is clear that PPPs are a model worth considering at scale for biotechnology. This discussion would be interesting to follow as the footprint of the bioeconomy continues to grow and as governments scrutinize the role of the bioeconomy in both societal and national security challenges and solutions. The opportunity to forge synergistic partnerships across sectors through BIOMADE and other similar PPPs is very meaningful. It is one where public sector players can work productively as partners to balance the public interest, including equity, fair access, inclusion, and environmental considerations with the market pull.

Immobilization of Tyrosinase and Its Application

Immobilized enzymes are more robust and resistant to environmental changes than free enzymes in solution. More crucially, the immobilized enzyme systems' heterogeneity enables facile recovery of enzymes and products, multiple reuses, continuous enzymatic processes, quick reaction termination, and a more comprehensive range of bioreactor designs. This paper examines recent findings on enzyme immobilization using diverse approaches for various uses. The information gathered from the reactions catalyzed by the encapsulated tyrosinase provided a good view of hetero-biocatalysts in the phenol biosensor industries. This review proposes an effective method for immobilizing tyrosinase biomolecules into a silica aerogel matrix. Silica matrix has been utilized to encapsulate a wide range of biomolecules, mainly in sol-gel composites. We also discovered that silica aerogel synthesized from sol-gel method retains all the immobilized enzyme activity. The use of a silica matrix for enzyme immobilization, in conjunction with a moderate immobilization method, results in the successful retention of enzyme activity. Future studies should explore practical encapsulating approaches and inventively modified supports to enhance the commercialization of immobilized enzymes and offer fresh perspectives to the industrial sector.

Scalable and High-Throughput In Vitro Vibratory Platform for Vocal Fold Tissue Engineering Applications.

The vocal folds (VFs) are constantly exposed to mechanical stimulation leading to changes in biomechanical properties, structure, and composition. The development of long-term strategies for VF treatment depends on the characterization of related cells, biomaterials, or engineered tissues in a controlled mechanical environment. Our aim was to design, develop, and characterize a scalable and high-throughput platform that mimics the mechanical microenvironment of the VFs in vitro. The platform consists of a 24-well plate fitted with a flexible membrane atop a waveguide equipped with piezoelectric speakers which allows for cells to be exposed to various phonatory stimuli. The displacements of the flexible membrane were characterized via Laser Doppler Vibrometry (LDV). Human VF fibroblasts and mesenchymal stem cells were seeded, exposed to various vibratory regimes, and the expression of pro-fibrotic and pro-inflammatory genes was analyzed. Compared to current bioreactor designs, the platform developed in this study can incorporate commercial assay formats ranging from 6- to 96-well plates which represents a significant improvement in scalability. This platform is modular and allows for tunable frequency regimes.

Oxygen and hydrocarbon volumetric transfer coefficients in the production of an oil-degrading bacterial consortium: emulsifying activity and surface tension in a bioreactor.

Our work shows that in multiphase systems, it is more important to take into account the mass transfer of oil rather than that of just oxygen. The oxygen volumetric transfer coefficient is important in aerobic bioreactor design. However, in multiphase systems with non-soluble substrates, oil transfer can impose larger restrictions but is usually not considered. Emulsification and surface tension could play an important role due to effects on oil droplet size and interfacial transfer area. Petroleum oil and is derivates such as diesel can negatively affect living organisms. This study evaluated the effects of the volumetric transfer coefficients (kLa) of hydrocarbons and oxygen on the production of an oil-degrading consortium in an airlift bioreactor relative to emulsifying activity and surface tension, which play important roles in the biodegradation of non-soluble substrates such as diesel due to a combined mass transfer constraint. Our results showed a clear difference in kLa values, which ranged from 15 to 91h-1 for oxygen and from 0 to 0.0014h-1 for diesel. Most aerobic biodegradation studies focus on the oxygen volumetric transfer coefficient (kLaoxygen), but our results indicated that non-soluble constraints, such as the volumetric transfer coefficient of diesel (kLadiesel), could be more important. Additionally, d32diesel decreased as superficial gas velocity (Ug) increased. Lower Ug rates (0.15cms-1) resulted in higher values of d32diesel (0.38cm-1), whereas higher Ug rates (2.7cms-1) resulted in lower values of d32diesel (0.21cm-1) at the beginning of the cultivation.

Interfacial interaction between ellipsoidal particle and membrane surface with random topographies

Modeling rough surfaces has received attention as it can facilitate understanding of colloidal systems. This work comprehensively discussed a facile approach for simulating the surface morphologies of ellipsoidal particles and membrane surfaces three-dimensionally. The fractal geometry theory was applied to construct a randomly rough surface. The assessment approach involving the surface element integral (SEI) method based on the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory was proposed to quantify the interfacial interaction between the constructed ellipsoidal particle and membrane surface. The simulated results demonstrated that the total interaction energy created between the particle and membrane surface was intensified by enlarging the particle and elevating the fractal dimension of the surface. The fractal roughness and orientation angle of the particle negatively affected the total interfacial energy between the particle and membrane surface. Moreover, the shape of the particle was found to have a profound effect on the total interaction energy. The new method has a wide range of potential applications in membrane bioreactor design and operation since it can predict the interaction of sludge flocs and membrane surface.

A novel low shear horizontal bioreactor design for the production of animal cells: Effect of bioreactor dynamics on the 3D spheroid formation of HepG2

Studies were carried out on a novel bioreactor designed for the production of animal cells. The aim is, to provide 3D cell proliferation under the influence of low gravity together with gentle mixing and low shear stress. HepG2 cells were used in the experiments to show that this bioreactor can provide low shear forces and a micro-gravity effect considering the results from its Computational Flow Dynamics (CFD) analyses. This bioreactor design has a horizontally positioned cylindrical body and two U-shaped agitators placed opposite to each other. This opposing blade formation, has a reducing effect on each other's hydrodynamic forces and forms a region with low shear stress character in the center of the bioreactor. First of all, the hydrodynamic forces formed inside this bioreactor, which was designed on the basis of CFD simulations, were examined. Afterwards, this novel designed low shear horizontal bioreactor (LSB-R) was manufactured according to the CFD analysis, and simulations. Then, production trials were conducted to determine the success of LSB-R in spheroid production. Thus, by evaluating results obtained from the production trials in accordance with cell culture, it has been shown that LSB-R, which design and patenting phase has been completed, can provide low shear stress.

Biogas Production and Metagenomic Analysis in a New Hybrid Anaerobic Labyrinth-Flow Bioreactor Treating Dairy Wastewater

Increasing worldwide milk manufacturing and dairy processing resulted in producing more effluents, and thus effective management of wastewater is now the most important issue. This study used a new design of a pilot plant-scale hybrid anaerobic labyrinth-flow bioreactor (AL-FB) to increase the efficiency of anaerobic biodegradation and biogas productivity and improve anaerobic microflora performance. In addition, effluent recirculation was used to boost the treatment of dairy wastewater. Metagenomic analyses of the anaerobic microbial community were performed. It was found that an organic loading rate (OLR) of 4.0–8.0 g COD/L·d contributed to the highest CH4 yield of 0.18 ± 0.01–0.23 ± 0.02 L CH4/g COD removed, which corresponded to a high COD removal of 87.5 ± 2.8–94.1 ± 1.3%. The evenest distribution of the microorganisms’ phyla determined the highest biogas production. In all tested samples, Bacteroidetes and Firmicutes abundance was the highest, and Archaea accounted for about 4%. Metagenomic studies showed that methane was mainly produced in acetoclastic methanogenesis; however, higher OLRs were more favorable for enhanced hydrogenotrophic methanogenesis. Effluent recirculation enhanced the overall treatment. Thus, at OLR of 10.0 g COD/L·d, the highest COD removal was 89.2 ± 0.4%, and methane production yield achieved 0.20 ± 0.01 L CH4/g COD removed, which was higher by 25% compared to the achievements without recirculation.

Bioreactor systems for micropropagation of plants: present scenario and future prospects.

Plant micropropagation has been adapted in the fields of agriculture, horticulture, forestry, and other related fields for large-scale production of elite plants. The use of liquid media and adoption of bioreactors have escalated the production of healthy plants. Several liquid-phase, gas-phase, temporary immersion, and other modified bioreactors have been used for plant propagation. The design, principle, operational mode, merits, and demerits of various bioreactors used for the regeneration of propagules, such as bulblets, cormlets, rhizomes, microtubers, shoots (subsequent rooting), and somatic embryos, are discussed here. In addition, various parameters that affect plant regeneration are discussed with suitable examples.

Description of new single-chamber continuous-flow reactors of aerobic granular sludge: Technical and biological study

Aerobic granular sludge reactors usually operate in sequential batch mode, although this configuration limits the treatment of large volumes of wastewater, and they require a storage system. To implement this technology at full-scale, it would be necessary to design a simple and compact continuous-flow bioreactor able to treat larger volumes of wastewater. In this study, four aerobic granular sludge single-chamber continuous-flow reactors (R1, R2, R3 and R4) were designed and operated at the lab scale to evaluate and select a bioreactor configuration that achieves high organic matter removal performance while maintaining a stable granulation for long-term operation, promoting the washout of filamentous microorganisms. Results confirmed that the bioreactor including a lateral decanter (R1), was able to work in a steady state without loss of granular biomass and reached 95% of organic matter removal performance. Its granules had excellent compaction, with settling velocity values above 100 m·h−1. The R1 bioreactor also allowed rapid biomass adaptation and therefore a fast start-up (11 days). Results of this preliminary study at the lab scale suggested that the new and simple bioreactor design could be promising for its implementation at full scale. For that, future research is required to optimise the current model and to determine the most suitable operational parameters to treat domestic wastewater at full scale.

Becoming settlers: Elements and mechanisms for surface colonization by Pseudomonas putida.

Pseudomonads are considered to be among the most widespread culturable bacteria in mesophilic environments. The evolutive success of Pseudomonas species can be attributed to their metabolic versatility, in combination with a set of additional functions that enhance their ability to colonize different niches. These include the production of secondary metabolites involved in iron acquisition or having a detrimental effect on potential competitors, different types of motility, and the capacity to establish and persist within biofilms. Although biofilm formation has been extensively studied using the opportunistic pathogen Pseudomonas aeruginosa as a model organism, a significant body of knowledge is also becoming available for non-pathogenic Pseudomonas. In this review, we focus on the mechanisms that allow Pseudomonas putida to colonize biotic and abiotic surfaces and adapt to sessile life, as a relevant persistence strategy in the environment. This species is of particular interest because it includes plant-beneficial strains, in which colonization of plant surfaces may be relevant, and strains used for environmental and biotechnological applications, where the design and functionality of biofilm-based bioreactors, for example, also have to take into account the efficiency of bacterial colonization of solid surfaces. This work reviews the current knowledge of mechanistic and regulatory aspects of biofilm formation by P. putida and pinpoints the prospects in this field.

Optimal Design of Double Stage Internal Loop Air-Lift Bioreactor

Biorefinery systems play a critical role in the transition towards a sustainable bioeconomy, and bioreactors are a key component in these systems. While mechanically stirred reactors have been extensively studied, there is a lack of research on pneumatically driven systems like air-lift reactors (ALRs). This study aims to address this gap by examining the hydrodynamic behavior of a double draft tube airlift bioreactor using Computational fluid dynamics simulations. Ten different geometric configurations were investigated, with variations in draft tube placement, liquid height, distance between draft tubes and draft tube diameters. Results showed that the placement of the draft tubes heavily influenced hydrodynamic behavior, with smaller distances between draft tubes and a funnel configuration leading to higher velocities. Stable downcomer velocities were achieved by maintaining a consistent distance between the bottom clearance and the sum of the distance between draft tubes and the bottom clearance on the top clearance. The model was validated against literature experimental data. This study provides insight into the optimal design of ALRs, which can contribute to the development of more efficient and effective bioreactor systems. The findings can be used to forecast the most optimal configurations of airlift bioreactors and have significant value for the development of more efficient biorefining concepts in light of the increasing importance of studying biorefineries and their components in the shift towards a biomass-based economy.

Improving accuracy of quantifying nitrate removal performance and enhancing understanding of processes in woodchip bioreactors using high-frequency data

Woodchip bioreactors have gained popularity in many countries as a conservation practice for reducing nitrate load to freshwater. However, current methods for assessing their performance may be inadequate when nitrate removal rates (RR) are determined from low-frequency (e.g., weekly) concurrent sampling at the inlet and outlet. We hypothesised that high-frequency monitoring data at multiple locations can help improve the accuracy of quantifying nitrate removal performance, enhance the understanding of processes occurring within a bioreactor, and therefore improve the design practice for bioreactors. Accordingly, the objectives of this study were to compare RRs calculated using high- and low-frequency sampling and assess the spatiotemporal variability of the nitrate removal within a bioreactor to unravel the processes occurring within a bioreactor. For two drainage seasons, we monitored nitrate concentrations at 21 locations on an hourly or two-hourly basis within a pilot-scale woodchip bioreactor in Tatuanui, New Zealand. A novel method was developed to account for the variable lag time between entry and exit of a parcel of sampled drainage water. Our results showed that this method not only enabled lag time to be accounted for but also helped quantify volumetric inefficiencies (e.g., dead zone) within the bioreactor. The average RR calculated using this method was significantly higher than the average RR calculated using conventional low-frequency methods. The average RRs of each of the quarter sections within the bioreactor were found to be different. 1-D transport modelling confirmed the effect of nitrate loading on the removal process as nitrate reduction followed Michaelis-Menten (MM) kinetics. These results demonstrate that high-frequency temporal and spatial monitoring of nitrate concentrations in the field allows improved description of bioreactor performance and better understanding of processes occurring within woodchip bioreactors. Thus, insights gained from this study can be used to optimise the design of future field bioreactors.

A Systematic Review of Syngas Bioconversion to Value-Added Products from 2012 to 2022

Synthesis gas (syngas) fermentation is a biological carbon fixation process through which carboxydotrophic acetogenic bacteria convert CO, CO2, and H2 into platform chemicals. To obtain an accurate overview of the syngas fermentation research and innovation from 2012 to 2022, a systematic search was performed on Web of Science and The Lens, focusing on academic publications and patents that were published or granted during this period. Overall, the research focus was centered on process optimization, the genetic manipulation of microorganisms, and bioreactor design, in order to increase the plethora of fermentation products and expand their possible applications. Most of the published research was initially funded and developed in the United States of America. However, over the years, European countries have become the major contributors to syngas fermentation research, followed by China. Syngas fermentation seems to be developing at “two-speeds”, with a small number of companies controlling the technology that is needed for large-scale applications, while academia still focuses on low technology readiness level (TRL) research. This systematic review also showed that the fermentation of raw syngas, the effects of syngas impurities on acetogen viability and product distribution, and the process integration of gasification and fermentation are currently underdeveloped research topics, in which an investment is needed to achieve technological breakthroughs.

A Matlab-Based Approach for Estimating the Area Taken Up by Cells Attached to Micropatterned Optically Opaque Surfaces

Abstract Cell attachment is of paramount importance in implant design, bioreactor design, tissue engineering and the design of non-fouling surfaces. Surface roughness is a significant factor that affects cell attachment. To explore the impact of roughness characteristics, micromachining approaches can be used to fabricate surfaces with controlled microscale topography. When optical microscopy is employed to study cell attachment to optically opaque micropatterned surfaces, one needs to separate the area of an image coated with cells from the background. Manual cell counting can be used to assess the amount of attached cells. However, this process is very time consuming, when the studied surface is larger than several square millimeters. This paper describes an approach for the automatic estimation of the area of cells attached to the surfaces of micro-patterned optically opaque platforms. Saccharomyces cerevisiae yeast cells were used to test the developed approach. The approach uses image registration and segmentation tools available in MathWorks MATLAB R2020b Image Processing Toolbox. The factors that affect the accuracy of the developed approach (magnification, contrast and focus) as well as the ways of improving the results are discussed.

Biocatalytic synthesis of 2'-deoxynucleotide 5'-triphosphates from bacterial genomic DNA: Proof of principle.

2'-deoxynucleoside 5'-triphosphates (dNTPs) are the building blocks of DNA and are key reagents which are incorporated by polymerase enzymes during nucleic acid amplification techniques, such as polymerase chain reaction (PCR). These techniques are of high importance, not only in molecular biology research, but also in molecular diagnostics. dNTPs are generally produced by a bottom-up technique which relies on synthesis or isolation of purified small molecules like deoxynucleosides. However, the disproportionately high cost of dNTPs in low- and middle-income countries (LMICs) and the requirement for cold chain storage during international shipping makes an adequate supply of these molecules challenging. To reduce supply chain dependency and promote domestic manufacturing in LMICs, a unique top-down biocatalytic synthesis method is described to produce dNTPs. Readily available bacterial genomic DNA provides a crude source material to generate dNTPs and is extracted directly from Escherichia coli (step 1). Nuclease enzymes are then used to digest the genomic DNA creating monophosphorylated deoxynucleotides (dNMPs) (step 2). Design and recombinant production and characterization of E. coli nucleotide kinases is presented to further phosphorylate the monophosphorylated products to generate dNTPs (step 3). Direct use of the in-house produced dNTPs in nucleic acid amplification is shown (step 4) and their successful use as reagents in the application of PCR, thereby providing proof of principle for the future development of recombinant nucleases and design of a recombinant solid-state bioreactor for on-demand dNTP production.

Performance of Biomass and Exopolysaccharide Production from the Medicinal Mushroom Ganoderma lucidum in a New Fabricated Air-L-Shaped Bioreactor (ALSB)

Conventional stirred-tank bioreactor (STR) designs are optimised for cultures of bacteria but not fungal cultures; therefore, a new Air-L-Shaped Bioreactor (ALSB) was fabricated. The ALSB was designed to eliminate the wall growth and clumping of fungal mycelium in STRs. Ganoderma lucidum was used as a fungal model and its biomass and exopolysaccharide (EPS) production were maximised by optimising the agitation rate, glucose concentration, initial pH, and aeration via response surface methodology (RSM). The ALSB system generated 7.8 g/L of biomass (biomass optimised conditions: 110 rpm, 24 g/L glucose, pH 5.6, and 3 v/v of aeration) and 4.4 g/L of EPS (EPS optimised conditions: 90 rpm, 30 g/L glucose, pH 4, and 2.5 v/v of aeration). In combination, for both optimised conditions, biomass (7.9 g/L) and EPS (4.6 g/L) were produced at 110 rpm, 30 g/L glucose, pH 4, and 3 v/v of aeration with minimal wall growth. The data prove that the ALSB is a blueprint for efficient economical fungal cultivation.

Hybrid bioreactor built-in with fixed bio-carriers for denitrification with low C/N ratio: Hydrodynamic optimization and microbial divergence

Hydrodynamics played an important role in the design and operation of bioreactors for wastewater treatment. In this work, an up-flow anaerobic hybrid bioreactor built-in with fixed bio-carriers was designed and optimized using computational fluid dynamics (CFD) simulation. The results indicated that the flow regime involving with vortex and dead zone was greatly affected by the positions of water inlet and bio-carrier modules. The ideal hydraulic features were obtained when the water inlet and bio-carrier modules located 9 cm and 60 cm above the bottom of reactor. Using the optimum hybrid system for nitrogen removal from wastewater with low carbon-to-nitrogen ratio (C/N = 3), the denitrification efficiency could reach 80.9 ± 0.4%. Illumina sequencing of 16S rRNA gene amplicons revealed that the microbial community divergence occurred among the biofilm on bio-carrier, the suspended sludge phase and the inoculum. Especially, the relative abundance of denitrifying genera Denitratisoma in the biofilm of bio-carrier reaches 5.73%, 6.2 times higher than that in the suspended sludge, implying the imbedded bio-carrier was conductive to enrich the specific denitrifiers to polish the denitrification performance with low carbon source. This work provided an effective method for the design optimization of bioreactor based on CFD simulation, and developed a hybrid reactor with fixed bio-carrier for nitrogen removal from wastewater with low C/N ratio.

Aspect ratio and baffles impact hydraulic performance of full-size denitrifying bioreactors

Denitrifying woodchip bioreactors treating subsurface drainage in the US have high aspect ratios (i.e., length: width ratios; approximately 4:1) to encourage plug flow dynamics. Improved understanding of bioreactor hydraulics across aspect ratios would help assess possible increased flexibility for this practice to capture greater hydraulic loading or provide greater nitrate mass removal. The objective of this study was to assess the hydraulic impacts of aspect ratio and baffles using conservative tracer testing at full-scale denitrifying woodchip bioreactors. Fourteen tracer tests were performed at six bioreactors, spanning three design styles: (1) “conventional” bioreactors with high aspect ratios of ≥2.6:1; (2) a “wide” bioreactor with a low aspect ratio of 0.3:1; and (3) a relatively wide “advanced” bioreactor with baffles placed to route flow sinuously perpendicular (sideways) to the hydraulic gradient. The wide bioreactor had the most dispersion, the most short circuiting, and was the most well mixed based on the tanks-in-series model. The advanced design with baffles had higher volumetric efficiencies than the conventional and wide designs (2.9, 2.2, and 2.1, respectively) and trended toward the highest nitrate removals. The concept of baffles at relatively wide bioreactors merits additional field-scale assessment to increase hydraulic loading while maintaining hydraulic efficiency. The Morill Dispersion and Short Circuiting Indices were strongly and significantly correlated (Pearson's r: −0.88) across the fourteen tests as were the volumetric and hydraulic efficiency metrics (r: 0.87). While aspect ratio and baffles have been well studied in wetlands and other reactor types, this work is the first to establish these concepts using tracer testing at three woodchip bioreactor design styles.

Techno-economic modeling and assessment of cultivated meat: Impact of production bioreactor scale.

Increases in global meat demands cannot be sustainably met with current methods of livestock farming, which has a substantial impact on greenhouse gas emissions, land use, water consumption, and farm animal welfare. Cultivated meat is a rapidly advancing technology that produces meat products by proliferating and differentiating animal stem cells in large bioreactors, avoiding conventional live-animal farming. While many companies are working in this area, there is a lack of existing infrastructure and experience at commercial scale, resulting in many technical bottlenecks such as scale-up of cell culture and media availability and costs. In this study, we evaluate theoretical cultivated beef production facilities with the goal of envisioning an industry with multiple facilities to produce in total 100,000,000 kg of cultured beef per year or ~0.14% of the annual global beef production. Using the computer-aided process design software, SuperPro Designer®, facilities are modeled to create a comprehensiveanalysis to highlight improvements that can lower the cost of such a production system and allow cultivated meat products to be competitive. Three facility scenarios are presented with different sized production reactors; ~42,000 L stirred tank bioreactor (STR) with a base case cost of goods sold (COGS) of $35/kg, ~211,000 L STR with a COGS of $25/kg, and ~262,000 L airlift reactor (ALR) with a COGS of $17/kg. This study outlines how advances in scaled up bioreactors, alternative bioreactor designs, and decreased media costs are necessary for commercialization of cultured meat products.

Customizable 3D printed perfusion bioreactor for the engineering of stem cell microenvironments.

Faithful modeling of tissues and organs requires the development of systems reflecting their dynamic 3D cellular architecture and organization. Current technologies suffer from a lack of design flexibility and complex prototyping, preventing their broad adoption by the scientific community. To make 3D cell culture more available and adaptable we here describe the use of the fused deposition modeling (FDM) technology to rapid-prototype 3D printed perfusion bioreactors. Our 3D printed bioreactors are made of polylactic acid resulting in reusable systems customizable in size and shape. Following design confirmation, our bioreactors were biologically validated for the culture of human mesenchymal stromal cells under perfusion for up to 2weeks on collagen scaffolds. Microenvironments of various size/volume (6-12mm in diameter) could be engineered, by modulating the 3D printed bioreactor design. Metabolic assay and confocal microscopy confirmed the homogenous mesenchymal cell distribution throughout the material pores. The resulting human microenvironments were further exploited for the maintenance of human hematopoietic stem cells. Following 1 week of stromal coculture, we report the recapitulation of 3D interactions between the mesenchymal and hematopoietic fractions, associated with a phenotypic expansion of the blood stem cell populations.Our data confirm that perfusion bioreactors fit for cell culture can be generated using a 3D printing technology and exploited for the 3D modeling of complex stem cell systems. Our approach opens the gates for a more faithful investigation of cellular processes in relation to a dynamic 3D microenvironment.