Current production costs of microalgal biomass indicate that only highly-productive cultivation facilities will approach commercial feasibility. Geographical site selection for siting those facilities is critical for achieving target productivities. The aim of this study was to provide a semi-empirical estimation of microalgal biomass and lipids productivity in South America. Simulated-climate was programed in environmental photobioreactors (PhenometricsTM) for a simulation of cultivation in open raceway ponds at different geographical sites. The mean annual South American biomass productivity of 20-cm deep ponds was 12 ± 4 g · m- 2 · d-1. The most productive regions were clustered in the subtropical and tropical regions of the continent. Fortaleza (Brazil) showed a low seasonality and a high annual mean productivity of 23 g · m-2 · d-1 in 5-cm deep ponds. Lipids accumulation and productivity in Fortaleza showed a high microalgal oil accumulation up to 46% (w/w) and a maximum oil productivity of 5 g · m-2 · d-1 for biomass containing around 20% lipids (w/w). This study provides the first semi-empirical estimation of microalgal productivity in South America and supports a high potential of a vast region of the continent.
Failure in the prevention of cross-transmission from contaminated gloves has been recognized as an important factor that contributes to the spread of several healthcare-associated infections. Ex situ coating process with silver nanoparticles (AgNPs) using Eucalyptus citriodora ethanolic leaf extract as reducing and capping agents to coat glove surfaces has been developed to prevent this mode of transmission. Elemental analysis of coated gloves showed 24.8 Wt% silver densely adhere on the glove surface. The coated gloves fully eradicated important hospital-acquired pathogens including Gram-positive bacteria, Gram-negative bacteria, and yeasts within 1 h. The coated gloves showed significant reduction, an average of 5 logs when tested against all standard strains and most clinical isolates (p < 0.01). Following prolonged exposure, the coating significantly reduced the numbers of most adhered pathogenic species, compared with uncoated gloves (p < 0.0001), which was observed by fluorescence microscopy. Scanning electron microscopy further confirmed that AgNPs coated-gloves reduced microbial adhesion of mixed-species biofilms, compared with uncoated gloves. A series of contamination and transmission assays demonstrated no transmission of viable organisms. Biocompatibility analysis confirmed high cell viability of HaCaT and L929 cells at all concentrations of AgNPs tested. The coated gloves were non-toxic with direct contact with L929 cells.
The European corn borer (ECB) Ostrinia nubilalis is a widespread pest of cereals. Mating disruption with the sex pheromone is a potentially attractive method for managing this pest. The goal of this study was to develop a biotechnological method for the production of ECB sex pheromone. Our approach was to engineer the oleaginous yeast Yarrowia lipolytica to produce (Z)-11-tetradecenol (Z11-14:OH), which can be chemically acetylated to (Z)-11-tetradecenyl acetate (Z11-14:OAc), the main pheromone component of the Z-race of O. nubilalis. Fatty acyl-CoA desaturases (FAD) and fatty acyl-CoA reductases (FAR) from nine different species of Lepidoptera were screened individually and in combinations. A titer of 29.2±1.6 mg/L Z11-14:OH was reached in small-scale cultivation with an optimal combination of a FAD (Lbo_PPTQ) from Lobesia botrana and FAR (HarFAR) from Helicoverpa armigera. When the second copies of FAD and FAR genes were introduced, the titer improved 2.1-fold. The native FAS1 gene’s overexpression led to a further 1.5-fold titer increase. When the same engineered strain was cultivated in controlled 1 L bioreactors in fed-batch mode, 188.1±13.4 mg/L of Z11-14:OH was obtained. Fatty alcohols were chemically acetylated to obtain Z11-14:OAc. Electroantennogram experiments showed that males of the Z-race of O. nubilalis were responsive to biologically-derived pheromone blend. Behavioral bioassays in a wind tunnel revealed attraction of male O. nubilalis at a level similar to that of the chemically synthesized pheromone used as a control, although full precopulatory behavior was observed less often. The study paves the way for the production of ECB pheromone by fermentation.
Ursolic acid (UA) is a ursane-type pentacyclic triterpenoid compound, naturally produced in plants via specialized metabolism and exhibits vast range of remarkable physiological activities and pharmacological manifestations. Owing to significant safety and efficacy in different medical conditions, UA may serve as a backbone to produce its derivatives with novel therapeutic functions. This review systematically provides an overview of the pharmacological activities, acquisition methods and structural modification methods of UA. In addition, we focused on the synthetic modifications of UA to yield its valuable derivatives with enhanced therapeutic potential. Furthermore, harnessing the essential advances for green synthesis of UA and its derivatives by advent of metabolic engineering and synthetic biology are highlighted. In combination with the advantages of UA biosynthesis and transformation strategy, large-scale production and applications of UA is a promising platform for further exploration.
Western equine encephalitis virus (WEEV) can cause lethal encephalitis in humans and equines and represents a serious public health threat in many countries. Therefore, development of efficient vaccines against WEEV remains an important challenge in the field of disease control. This study described for the first time successful production of WEEV virus-like particles (VLPs) in insect cells using recombinant baculoviruses. This well-established expression system is very suitable for production of WEEV VLPs. The immune experiment herein in mice showed that the VLPs formulated with 206-adjuvant were responsible for the stronger-VLP-specific cellular immune response, and were able to induce the secretion of IL-2, IL-4, IFN-γ and production of high titer antibodies that can effectively neutralize the WEEV pseudoviruses. The WEEV VLPs from insect cells could provide a new, safe, non-replicating and effective vaccine candidate against WEEV infections.
Bioprocess development and optimization is a challenging, costly, and time-consuming effort. In this multidisciplinary task, upstream processing (USP) and downstream processing (DSP) are conventionally considered distinct disciplines. This consideration fosters “one-way” optimization without considering interdependencies between unit operations; thus, the full potential of the process chain cannot be achieved. Therefore, it is necessary to fully integrate USP and DSP process development to provide balanced biotechnological production processes. The aim of the present study was to investigate how different host/leader/antigen binding fragment (Fab) combinations in E. coli expression systems influence USP and primary recovery performance and the final product quality. We ran identical fed-batch cultivations with 16 different expression clones to study growth and product formation kinetics, as well as centrifugation efficiency, viscosity, extracellular DNA, and endotoxin content, which are important parameters in DSP. We observed a severe influence on cell growth, product titer, extracellular product, and cell lysis, accompanied by a significant impact on the analyzed parameters of DSP performance. Our results provide the basis for establishing integrated process development considering interdependencies between USP and DSP. These interdependencies need to be understood for rational decision-making and efficient process development.
In recent years Next-Generation Sequencing (NGS) based methods to detect mutations in biotherapeutic transgene products have become a key quality step deployed during the development of manufacturing cell line clones. Previously we reported on a higher throughput, rapid mutation detection method based on amplicon sequencing (targeting transgene RNA) and detailed its implementation to facilitate cell line clone selection. By gaining experience with our assay in a diverse set of cell line development programs, we improved the computational analysis as well as experimental protocols. Here we report on these improvements as well as on a comprehensive benchmarking of our assay. We evaluated assay performance by mixing amplicon samples of a verified mutated antibody clone with a non-mutated antibody clone to generate spike-in mutations from ~60% down to ~0.3% frequencies. We subsequently tested the effect of 16 different sample and NGS library preparation protocols on the assay’s ability to quantify mutations and on the occurrence of false-positive background error mutations (artifacts). Our evaluation confirmed assay robustness, established a high confidence limit of detection of ~0.6%, and identified protocols that reduce error levels thereby significantly reducing a source of false positives that bottlenecked the identification of low-level true mutations.
The production of recombinant proteins usually reduces cell fitness and the growth rate of producing cells. The growth disadvantage favors faster-growing non-producer mutants. Therefore, continuous bioprocessing is hardly feasible in Escherichia coli due to the high escape rate. We investigated the stability of E. coli expression systems under long-term production conditions and how metabolic load triggered by recombinant gene expression influences the characteristics of mutations. We conducted iterated fed-batch-like microbioreactor cultivations under production conditions. We used the easy-to-produce green fluorescent protein (GFP) and a challenging antigen-binding fragment (Fab) as model proteins, and BL21(DE3) and BL21Q strains as expression hosts. In comparative whole genome sequencing analyses, we identified mutations that allowed cells to grow unhindered despite recombinant protein production. A T7 RNA polymerase expression system is only conditionally suitable for long-term cultivation under production conditions. Mutations leading to non-producers occur in either the T7 RNA polymerase gene or the T7 promoter. The host RNA polymerase-based BL21Q expression system remained stable in the production of GFP in long-term cultivations. For the production of Fab, mutations in lacI of the BL21Q derivatives had positive effects on long-term stability. Our results indicate that adaptive evolution carried out with genome-integrated E. coli expression systems in microtiter cultivations under industrial relevant production conditions is an efficient strain development tool for production hosts.
We report a novel Cultured Neuronal Network on a chip as a viable alternative to current culture methods for the analysis of neuronal network formation and evolution of the structural properties of the network's graph . This innovative microfluidic chip fabricated from Polydimethylsiloxane, vinyl, and glass offers worthy features such as the posibility to develop and produce custom designs effortlessly, easy handling and monitoring, culture medium renewal, and reducing the exposure to contamination. Due to these benefits, longer survival of the neuronal networks are observed in comparison to conventional methods. In addition to the fast and cost-effective manufacturing of the chip, this technology provides a significant step forward in the studies of neuronal network development and many challening applications such as drug testing of in vitro cell culture models .
Biomolecules are increasingly attractive templates for the synthesis of functional nanomaterials. Chief among them are the plant Tobacco mosaic virus (TMV) and Barley stripe mosaic virus (BSMV) due to their high aspect ratio, narrow size distribution, diverse biochemical functionalities presented on the surface, and compatibility with a number of chemical conjugations. These properties are also easily manipulated by genetic modification to enable the synthesis of a range of metallic and non-metallic nanomaterials for diverse applications. This article reviews the characteristics of TMV, BSMV, and their virus-like particle (VLP) derivatives and how these may be manipulated to extend their use and function. A focus of recent efforts has been on greater understanding and control of the self-assembly processes that drive biotemplate formation. We briefly outline how these features have been exploited in engineering applications such as sensing, catalysis, and energy storage, and discuss emerging advances that promise to accelerate the development of these biotemplates for widescale industrial use.
Microbial conversion of plant biomass into fuels and chemicals offers a practical solution to global concerns on limited natural resources, environmental pollution, and climate change. Pursuant to these goals, researchers have put tremendous efforts and resources towards engineering the yeast Saccharomyces cerevisiae to efficiently convert xylose, the second most abundant sugar in lignocellulosic biomass, into various fuels and chemicals. Although many challenges remain, these research investments have facilitated efficient and rapid fermentation of xylose, simultaneous co-consumption of xylose with carbon sources in lignocellulosic hydrolysates, and enhanced production of a wide range of valuable chemicals from xylose. In particular, understanding of xylose-induced metabolic rewiring in engineered yeast has stimulated the use of xylose as a preferred carbon source for the production of various non-ethanol bioproducts. Here, we summarize recent advances in metabolic engineering in yeast to address bottlenecks of xylose assimilation, and to enable simultaneous co-utilization of xylose and other cellulosic carbon sources. We also highlight distinct characteristics of xylose metabolism which can be harnessed for the production of advanced biofuels and chemicals.
Nascent advanced therapies, including regenerative medicine and cell and gene therapies, rely on the production of cells in bioreactors that are highly heterogeneous in both space and time. Unfortunately, these promising therapies have failed to reach a wide patient population due to unreliable manufacturing processes that result in batch variability and cost prohibitive production. This can be attributed largely to a void in existing process analytical technologies (PATs) capable of characterizing the secreted critical quality attributes (CQAs) biomolecules that correlate with the final product quality. The Dynamic Sampling Platform (DSP) is a PAT for cell bioreactor monitoring that can be coupled to a suite of sensor techniques to provide real-time feedback on spatial and temporal CQA content in situ. In this study, DSP is coupled with electrospray ionization mass spectrometry (ESI-MS) and direct-from-culture sampling to obtain measures of CQA content in bulk media and the cell microenvironment throughout the entire cell culture process (~3 weeks). Post hoc analysis of this real-time data reveals that DSP output is heavily dependent on spatial context. Importantly, these results demonstrate that an effective PAT must incorporate both spatial and temporal resolution to serve as an effective input f or feedback control in advanced therapy production.
Bioprocess optimization for cell-based therapies is a resource heavy activity. To reduce the associated cost and time, it is advantageous to carry out process development in small volume systems, with the caveat that such systems be predictive for process scaleup. The transport of oxygen from the gas phase into the culture medium, characterized using the volumetric mass transfer coefficient, kLa, has been identified as a critical parameter for predictive process scaleup. In both large- and small-scale bioreactors, kLa is controlled via mixing, with the method employed dependent upon the size of the reactor. However, existing microplate bioreactor platforms, beneficial for their low working volumes and throughput and automation capabilities, struggle to achieve desired kLa for mammalian cell cultures. Here, we describe the development and testing of a 96-well microplate with integrated Redbud Posts to provide mixing and thus enhanced kLa. Mixing characteristics were investigated, with actuating Redbud Posts shown (visually) to increase convective transport while producing enhanced kLa, providing means to mimic macroscale mammalian cell growth conditions at the microscale. Improved cell growth rates with mixing was demonstrated for two cell types, indicating the potential for this technology to play a valuable role in early stage bioprocess development and optimization.
Transient gene expression (TGE) using mammalian cells is an extensively used technology for production of antibodies and recombinant proteins and has been widely adapted by both academic and industrial labs. Chinese Hamster Ovary (CHO) cells have become one of the major work horses for TGE of recombinant antibodies due to their attractive features: post-translational modifications, adaptation to high cell densities, and use of serum-free media. In this study, we describe the optimization of parameters for TGE for antibodies from CHO cells. Through a matrix evaluation of multiple factors including inoculum, transfection conditions, amount and type of DNA used and post-transfection culture conditions, we arrived at an optimized process with higher titer and reduced costs and time, thus increasing the overall efficiency of early antibody material supply. We investigated the amount of coding DNA and the influence of size of the transfection complex on the in vitro efficiency of the transfection. Generation of the transfection complex in serum-free medium leads to the prompt formation of an optimal-sized polyplex, and is independent of the relative amount of coding DNA used for a successful transfection outcome.
As a milestone in soft and hard tissue engineering, a precise control over the micropatterns of scaffolds have lightened new opportunities for the recapitulation of native body organs through 3D bioprinting approaches. Well-printable bioinks are pre-requisites for the bioprinting of tissues/organs where hydrogels play a critical role. Despite the outstanding developments in 3D engineered microstructures, current printer devices, suffer from the risk of exposing loaded living agents to mechanical (nozzle-based) and thermal (nozzle-free) stresses. Thus, tuning the rheological, physical, and mechanical properties of hydrogels are promising solutions to address these issues. The relationship between the mechanical characteristics of hydrogels and their printability is important to control printing quality and fidelity. Recent developments in defining this relationship have highlighted the decisive role of main additive manufacturing strategies. These strategies are applied to enhance the printing quality of scaffolds and determine the nurture of cellular morphology. In this regard, it is beneficial to use external and internal stabilization, photo curable biopolymers, and cooling substrates containing the printed scaffolds. The objective of this study was to review cutting-edge developments in hydrogel-type bioinks and discuss the optimum simulation of the zonal stratification in osteochondral and cartilage units.
Interfaces between biomaterials and living system are critical in regulating their interactions. Poor biocontact properties always limited the performance of biomaterials in biological environment. Surface engineering aims to control the interface interaction to further enhance the desired behavior of biomaterials. Upon implantation of biomaterials into the biological environment, a series of host responses are initiated. Non-specific protein adsorption on biomaterials is the essential stage of all biological reactions that associated with implants failure, device-related infections and blood-coagulation. In this review, we first focused on surface modification techniques to eliminate protein adsorption by emphasizing PEGylation of both macroscopic surface and nanoparticle system. Next, recent developments in surface engineering of biomaterials to optimize interactions between biomaterials and specific host tissue and organs are discussed. Optimizing the biocontact property of blood-contact devices can improve their hemocompatibility and maintain vascular homeostasis. Surface modifications of orthopedic and dental implants confer improved osteointegration and tribology performance. Controlling the surface chemistry and topography, and immobilizing biomolecules can aid the expansion and direct the differentiation of stem cells.
The current industrial production of polymer building blocks such as ε-caprolactone (ε-CL) and 6-hydroxyhexanoic acid (6HA) is a multi-step process associated with critical environmental issues such as the generation of toxic waste and high energy consumption. Consequently, there is a demand for more eco-efficient and sustainable production routes. This study deals with the generation of a platform organism that converts cyclohexane to such polymer building blocks without the formation of byproducts and under environmentally benign conditions. Based on kinetic and thermodynamic analyses of the individual enzymatic steps, we rationally engineered a 4-step enzymatic cascade in Pseudomonas taiwanensis VLB120 via stepwise biocatalyst improvement on the genetic level. We found that the intermediate product cyclohexanol severely inhibits the cascade and optimized the cascade by enhancing the expression level of downstream enzymes. The integration of a lactonase enabled exclusive 6HA formation without side products. The resulting biocatalyst showed a high activity of 44.8 ± 0.2 U gCDW-1 and fully converted 5 mM cyclohexane to 6HA within 3 h. This platform organism can now serve as a basis for the development of greener production processes for polycaprolactone and related polymers.
Today’s available therapies to treat patients infected with human immunodeficiency virus (HIV) aim at preventing viral replication and transmission but fail to eliminate the virus. Although transplantation of an allogeneic CCR5Δ32 homozygous stem cell grafts provided a cure for three patients, this approach is not considered a general therapeutic strategy because of potential severe side effects. Conversely, genome editing to disrupt the CCR5 locus that encodes the major HIV coreceptor was shown to confer resistance to R5-tropic HIV strains on the cellular level. Here, we present a clinically relevant and highly efficient approach to produce HIV-1 resistant CD4+ T cells. After transferring mRNA coding for CCR5-targeting TALEN into CD4+ T cells by electroporation, up to 89% of CCR5 alleles were disrupted. Genotyping confirmed genetic stability of the edited cell product and off-target analyses established absence of relevant mutagenic events. When challenging these edited T cells with R5-tropic HIV, we observed protection in a dose-dependent manner. Functional assessments revealed no significant differences between edited and control CD4+ T cells in terms of proliferation capacity and their ability to secrete cytokines upon exogenous stimuli. Overall, we successfully engineered HIV-resistant CD4+ T cells under clinically relevant conditions, paving the way for clinical translation.