Synthetic biology approaches and bioseparations in syngas fermentation.

Fossil fuel use drives greenhouse gas emissions and climate change, highlighting the need for alternatives like biomass-derived syngas. Syngas, mainly H2 and CO, is produced via biomass gasification and offers a solution to environmental challenges. Syngas fermentation through the Wood-Ljungdahl pathway yields valuable chemicals under mild conditions. However, challenges in scaling up persist due to issues like unpredictable syngas composition and microbial fermentation contamination. This review covers advancements in genetic tools and metabolic engineering to expand product range, highlighting crucial enabling technologies that expedite strain development for acetogens and other non-model organisms. This review paper provides an in-depth exploration of syngas fermentation, covering microorganisms, gas composition effects, separation techniques, techno economic analysis, and commercialization efforts.

Escherichia coli-based biorefining process yields optically pure lactic acid from fermented second-generation feedstocks.

Within the circular bioeconomy the production of optically pure LA from 2nd generation feedstocks would be ideal but it is very challenging. In this paper genetically engineered Escherichia coli strains were created to resolve racemic LA solutions synthesised and produced from the fermentation of organic waste or ensiled grass. Refining LA racemic mixtures into either a D- or L-LA was achieved by cells being able to consume one LA isomer as a sole carbon and energy source while not being able to consume the other. A D-LA refining strain JSP0005 was grown on fermented source-sorted organic household waste and different grass silage leachates, which are 2nd generation feedstocks containing up to 33 g/L lactic acid racemate. In all growth experiments, L-LA was completely removed leaving D-LA as the only LA stereoisomer, i.e. resulting in optically pure D-LA, which also increased by as much as 248.6 % from its starting concentration, corresponding to 38 g/L. The strains resulting from this study are a promising first step towards a microbial based LA biorefining process.

DOE-based process optimization for development of efficient methods for purification of recombinant hepatitis B surface antigen from Pichia pastoris feedstock using Capto adhere resin.

Background: The multimodal chromatography resins, such as Capto adhere, are considered good candidates to be utilized in downstream processing due to their high capacity and selectivity; however, their multimodal interactions lead to an intricacy in the adsorption-desorption patterns and systematic characterization of conditions for process steps is necessary. Methods: Capto adhere, a strong ion exchanger with multimodal functionality, was used in this study for the final aim of recombinant hepatitis B surface antigen (rHBsAg) purification from Pichia pastoris (P. pastoris) industrial feedstock. Optimization of various parameters was done using the design of experiments (DOE) approach to determine the best binding and non-binding conditions. Results: Maximum rHBsAg binding on Capto adhere occurred in 20 mM sodium acetate, pH 4.5, and a binding capacity of about 0.75 mg/ml was achieved, which was much higher than rHBsAg binding capacity of other resins reported so far. In elution optimization investigations, it was revealed that 1 M arginine (buffered in 50 mM sodium phosphate, pH 6.5) was the most efficient eluting agent. The binding and elution optimal conditions were utilized for further purification of rHBsAg from P. pastoris industrial feedstock in bind-elute mode, and the recovery and purity of the obtained rHBsAg were about 60% and 100%, respectively. Following optimization in the flow-through purification mode, the target protein recovery was significantly increased (up to 97%) and the target protein purity of more than 95% was achievable. SEC-HPLC analysis showed that the obtained retention times for the purified rHBsAg were similar to those reported previously. Conclusions: These results suggest that Capto adhere under such optimized conditions can be considered as a good candidate for efficient purification of rHBsAg from P. pastoris industrial feedstock in downstream processing.

Balancing pH and yield: exploring itaconic acid production in Ustilago cynodontis from an economic perspective.

BACKGROUND: Itaconic acid is a promising bio-based building block for the synthesis of polymers, plastics, fibers and other materials. In recent years, Ustilago cynodontis has emerged as an additional itaconate producing non-conventional yeast, mainly due to its high acid tolerance, which significantly reduces saline waste coproduction during fermentation and downstream processing. As a result, this could likely improve the economic viability of the itaconic acid production process with Ustilaginaceae. RESULTS: In this study, we characterized a previously engineered itaconate hyper-producing Ustilago cynodontis strain in controlled fed-batch fermentations to determine the minimal and optimal pH for itaconate production. Under optimal fermentation conditions, the hyper-producing strain can achieve the theoretical maximal itaconate yield during the production phase in a fermentation at pH 3.6, but at the expense of considerable base addition. Base consumption is strongly reduced at the pH of 2.8, but at cost of production yield, titer, and rate. A techno-economic analysis based on the entire process demonstrated that savings due to an additional decrease in pH control reagents and saline waste costs cannot compensate the yield loss observed at the highly acidic pH value 2.8. CONCLUSIONS: Overall, this work provides novel data regarding the balancing of yield, titer, and rate in the context of pH, thereby contributing to a better understanding of the itaconic acid production process with Ustilago cynodontis, especially from an economic perspective.

Process analytical technology in Downstream-Processing of Drug Substances- A review.

Process Analytical Technology (PAT) has revolutionized pharmaceutical manufacturing by providing real-time monitoring and control capabilities throughout the production process. This review paper comprehensively examines the application of PAT methodologies specifically in the production of solid active pharmaceutical ingredients (APIs). Beginning with an overview of PAT principles and objectives, the paper explores the integration of advanced analytical techniques such as spectroscopy, imaging modalities and others into solid API substance production processes. Novel developments in in-line monitoring at academic level are also discussed. Emphasis is placed on the role of PAT in ensuring product quality, consistency, and compliance with regulatory requirements. Examples from existing literature illustrate the practical implementation of PAT in solid API substance production, including work-up, crystallization, filtration, and drying processes. The review addresses the quality and reliability of the measurement technologies, aspects of process implementation and handling, the integration of data treatment algorithms and current challenges. Overall, this review provides valuable insights into the transformative impact of PAT on enhancing pharmaceutical manufacturing processes for solid API substances.

Insulin evolution: A holistic view of recombinant production advancements.

The increased prevalence of diabetes and the growing popularity of non-invasive methods of recombinant human insulin uptake, such as oral insulin, have increased insulin demand, further limiting the affordability of insulin. Over 40 years have passed since the development of engineered microorganisms that replaced the animal pancreas as the primary source of insulin. To stay ahead of the need for insulin in the present and the future, a few drawbacks with the existing expression systems need to be alleviated, including the inclusion body formation, the use of toxic inducers, and high process costs. To address these bottlenecks and improve insulin production, a variety of techniques are being used in bacteria, yeasts, transgenic plants and animals, mammalian cell lines, and cell-free expression systems. Different approaches for the production of insulin, including two-chain, proinsulin or mini-proinsulin, preproinsulin coupled with fusion protein, chaperone, signal peptide, and purification tags, are explored in upstream, whereas downstream processing takes into account the recovery of intact protein in its bioactive form and purity. This article focuses on the strategies used in the upstream and downstream phases of the bioprocess to produce recombinant human insulin. This review also covers a range of analytical methods and tools employed in investigating the genuity of recombinant human insulin.

Recovery and encapsulation of Dunaliella salina ß-carotene through a novel sustainable approach: Sequential application of an ionic liquid as naturally-derived solvent and emulsifier.

Dunaliella salina is a promising source of ß-carotene, widely employed in the food industry. This study aimed to evaluate the sequential application of the Ionic Liquid (IL) cholinium oleate as an extraction solvent for D. salina ß-carotene recovery and, sequentially, as emulsifier for emulsion-based products obtained therefrom. The IL was evaluated regarding its ability to permeabilize the cells and recover ß-carotene at different temperatures (25-65 °C) and IL concentrations (0-46%). The use of the IL as solvent greatly improved ß-carotene recovery (>84%). The IL already present in the obtained extracts loaded with recovered ß-carotene was sequentially used as emulsifier in the production of nanoemulsions (NE). NE presented a ß-carotene entrapment efficiency of 100% and were kinetically stable for 30 days and presented droplet size, size distribution, and ζ-potential of 220 nm, 0.21, and -67 mV, respectively. These results indicate that using IL sequential as solvent and emulsifier has potential applications in the food industry.

Scalable microfluidic method for tunable liposomal production by a design of experiment approach.

Liposomes constitute a widespread drug delivery platform, gaining more and more attention from the pharmaceutical industry and process development scientists. Their large-scale production as medicinal products for human use is all but trivial, especially when parenteral administration is required. In this study an off-the-shelf microfluidic system and a methodological approach are presented for the optimization, validation and scale-up of highly monodisperse liposomes manufacturing. Starting from a Doxil®-like formulation (HSPC, MPEG-DSPE and cholesterol), a rational approach (Design of Experiments, DoE) was applied for the screening of the process parameters affecting the quality attributes of the product (mainly size and polydispersity). Additional DoEs were conducted to determine the effect of critical process parameters "CPPs" (cholesterol concentration, total flow rate "TFR" and flow rate ratio "FRR"), thus assessing the formulation and process robustness. A scale-up was then successfully accomplished. The procedure was applied to a Marqibo®-like formulation as well (sphingomyelin and cholesterol) to show the generality of the proposed formulation, process development and scale-up approach. The application of the system and method herein presented enables the large-scale manufacturing of liposomes, in compliance with the internationally recognized regulatory standards for pharmaceutical development (Quality by Design).

A review on microbes mediated resource recovery and bioplastic (polyhydroxyalkanoates) production from wastewater.

BACKGROUND: Plastic is widely utilized in packaging, frameworks, and as coverings material. Its overconsumption and slow degradation, pose threats to ecosystems due to its toxic effects. While polyhydroxyalkanoates (PHA) offer a sustainable alternative to petroleum-based plastics, their production costs present significant obstacles to global adoption. On the other side, a multitude of household and industrial activities generate substantial volumes of wastewater containing both organic and inorganic contaminants. This not only poses a threat to ecosystems but also presents opportunities to get benefits from the circular economy. Production of bioplastics may be improved by using the nutrients and minerals in wastewater as a feedstock for microbial fermentation. Strategies like feast-famine culture, mixed-consortia culture, and integrated processes have been developed for PHA production from highly polluted wastewater with high organic loads. Various process parameters like organic loading rate, organic content (volatile fatty acids), dissolved oxygen, operating pH, and temperature also have critical roles in PHA accumulation in microbial biomass. Research advances are also going on in downstream and recovery of PHA utilizing a combination of physical and chemical (halogenated solvents, surfactants, green solvents) methods. This review highlights recent developments in upcycling wastewater resources into PHA, encompassing various production strategies, downstream processing methodologies, and techno-economic analyses. SHORT CONCLUSION: Organic carbon and nitrogen present in wastewater offer a promising, cost-effective source for producing bioplastic. Previous attempts have focused on enhancing productivity through optimizing culture systems and growth conditions. However, despite technological progress, significant challenges persist, such as low productivity, intricate downstream processing, scalability issues, and the properties of resulting PHA.

Expression of Multispecific Antibodies.

Bi- and multispecific antibody formats allow the development of new therapeutic strategies to address previously unmet medical needs. However, due to the increased complexity (e.g., the interface design and the presence of multiple binders), such molecules are generally more challenging to express and purify compared to standard monoclonal antibodies (mAbs). We describe here an optimized methodology to express and purify basic bispecific antibodies using the BEAT® interface. This interface allows to generate antibodies with very high levels of heterodimer product (reported titers exceed 10 g/L) and comes with a built-in purification strategy allowing removal of residual levels of undesired product-related impurities (e.g., homodimers and half molecules).

Unraveling the structural aspects of microwave-assisted OrganoCat-based coconut shell lignins: An eco-friendly route for obtaining bio-based antioxidants.

New routes for biomass valorization have been developing by the scientific community. The aim of this work was developing a novel OrganoCat-based protocol and deeply understand the structure of the obtained lignins. Microwave-assisted OrganoCat-based process was performed using a biphasic system (ethyl acetate and oxalic acid or HCl) at mild conditions. OrganoCat-based lignins (OCLs) were characterized by compositional analysis, FTIR, 1H, 13C, 1H13C HSQC, 31P NMR, TGA and GPC. The solubility of OCLs in different organic solvents and their antioxidant capacity against DPPH were investigated. The spectroscopic analyses showed that OCLs have high residual extractives and the lignin motifs were preserved. OCLs have presented lower thermal stability than MWL, but showed great antioxidant activities and high solubility in a wide range of organic solvents. A novel biorefinery protocol yielded coconut shell lignins with peculiar structural and compositional features and several technological applications through an eco-friendly, sustainable and relatively low-cost biphasic pulping process.

Lentiviral vector determinants of anion-exchange chromatography elution heterogeneity.

The demand for Lentiviral Vector (LV) drug substance is increasing. However, primary capture using convective anion-exchange chromatography remains a significant manufacturing challenge. This stems from a poor understanding of the complex adsorption behaviors linked to LVs intricate and variable structure, such as high binding heterogeneity which is typically characterized by a gradient elution profile consisting of two peaks. Understanding which LV structural components drive these phenomena is therefore crucial for rational process design. This work identifies the key LV envelope components responsible for binding to quaternary-amine membrane adsorbents. Eliminating the pseudotype protein (Vesicular Stomatitis Virus G glycoprotein [VSV-G]) did not impact the heterogenous two-peak elution profile, suggesting it is not a major binding species. Digestion of envelope glycosaminoglycans (GAGs), present on proteoglycans, leads to a dramatic reduction in the proportion of vector eluted in peak 2, decreasing from 50% to 3.1%, and a threefold increase in peak 1 maximum. Data from reinjection experiments point towards interparticle envelope heterogeneity from discrete LV populations, where the two-peak profile emerges from a subpopulation of LVs interacting via highly charged GAGs (peak 2) along with a weaker binding population likely interacting through the phospholipid membrane and envelope protein (peak 1).

Purification of recombinantly produced somatostatin-28 comparing hydrochloric acid and polyethyleneimine as E. coli extraction aids.

Peptides are used for diagnostics, therapeutics, and as antimicrobial agents. Most peptides are produced by chemical synthesis, but recombinant production has recently become an attractive alternative due to the advantages of high titers, less toxic waste and correct folding of tertiary structure. Somatostatin-28 is a peptide hormone that regulates the endocrine system, cell proliferation and inhibits the release of numerous secondary hormones in human body. It is composed of 28 amino acids and has one disulfide bond, which makes it to an optimal model peptide for a whole downstream purification process. We produced the peptide in the periplasm of E. coli using the CASPON™ technology, an affinity fusion technology system that enables high soluble expression of recombinant proteins and cleaves the fusion tag with a circularly permuted human caspase-2. Furthermore, purification of the products is straight forward using an established platform process. Two different case studies for downstream purification are presented, starting with either hydrochloric acid or polyethyleneimine as an extraction aid. After release of affinity-tagged somatostatin-28 out of E. coli's periplasm, several purification steps were performed, delivering a pure peptide solution after the final polishing step. The process was monitored by reversed-phase high-performance liquid chromatography as well as mass spectrometry to determine the yield and correct disulfide bond formation. Monitoring of impurities like host cell proteins, DNA and endotoxins after each downstream unit confirmed effective removal for both purification pathways.

Current trends in medium-chain-length polyhydroxyalkanoates: Microbial production, purification, and characterization.

Polyhydroxyalkanoates (PHAs) have gained interest recently due to their biodegradability and versatility. In particular, the chemical compositions of medium-chain-length (mcl)-PHAs are highly diverse, comprising different monomers containing 6-14 carbon atoms. This review summarizes different feedstocks and fermentation strategies to enhance mcl-PHA production and briefly discusses the downstream processing. This review also provides comprehensive details on analytical tools for determining the composition and properties of mcl-PHA. Moreover, this study provides novel information by statistically analyzing the data collected from several reports on mcl-PHA to determine the optimal fermentation parameters (specific growth rate, PHA productivity, and PHA yield from various structurally related and unrelated substrates), mcl-PHA composition, molecular weight (MW), and thermal and mechanical properties, in addition to other relevant statistical values. The analysis revealed that the median PHA productivity observed in the fed-batch feeding strategy was 0.4 g L-1 h-1, which is eight times higher than that obtained from batch feeding (0.05 g L-1 h-1). Furthermore, 3-hydroxyoctanoate and -decanoate were the primary monomers incorporated into mcl-PHA. The investigation also determined the median glass transition temperature (-43°C) and melting temperature (47°C), which indicated that mcl-PHA is a flexible amorphous polymer at room temperature with a median MW of 104 kDa. However, information on the monomer composition or heterogeneity and the associated physical and mechanical data of mcl-PHAs is inadequate. Based on their mechanical values, the mcl-PHAs can be classified as semi-crystalline polymers (median crystallinity 23%) with rubber-like properties and a median elongation at break of 385%. However, due to the limited mechanical data available for mcl-PHAs with known monomer composition, identifying suitable processing tools and applications to develop mcl-PHAs further is challenging.

Expediting online liquid chromatography for real-time monitoring of product attributes to advance process analytical technology in downstream processing of biopharmaceuticals.

The application of Process Analytical Technology (PAT) principles for manufacturing of biotherapeutics proffers the prospect of ensuring consistent product quality along with increased productivity as well as substantial cost and time savings. Although this paradigm shift from a traditional, rather rigid manufacturing model to a more scientific, risk-based approach has been advocated by health authorities for almost two decades, the practical implementation of PAT in the biopharmaceutical industry is still limited by the lack of fit-for-purpose analytical methods. In this regard, most of the proposed spectroscopic techniques are sufficiently fast but exhibit deficiencies in terms of selectivity and sensitivity, while well-established offline methods, such as (ultra-)high-performance liquid chromatography, are generally considered as too slow for this task. To address these reservations, we introduce here a novel online Liquid Chromatography (LC) setup that was specifically designed to enable real-time monitoring of critical product quality attributes during time-sensitive purification operations in downstream processing. Using this online LC solution in combination with fast, purpose-built analytical methods, sampling cycle times between 1.30 and 2.35 min were achieved, without compromising on the ability to resolve and quantify the product variants of interest. The capabilities of our approach are ultimately assessed in three case studies, involving various biotherapeutic modalities, downstream processes and analytical chromatographic separation modes. Altogether, our results highlight the expansive opportunities of online LC based applications to serve as a PAT tool for biopharmaceutical manufacturing.

Factors impacting the microbial production of eicosapentaenoic acid.

The increasing applications for eicosapentaenoic acid (EPA) and the potential shortfall in supply due to sustainability and contamination issues related with its conventional sources (i.e., fish oils; seafood) led to an extensive search for alternative and sustainable sources, as well as production processes. The present mini-review covers all the steps involved in the production of EPA from microorganisms, with a deeper focus on microalgae. From production systems to downstream processing, the most important achievements within each area are briefly highlighted. Comparative tables of methodologies are also provided, as well as additional references of recent reviews, so that readers may deepen their knowledge in the different issues addressed. KEY POINTS: • Microorganisms are more sustainable alternative sources of EPA than fish. • Due to the costly separation from DHA, species that produce only EPA are preferable. • EPA production can be optimised using non-genetic and genetic tailoring engineering.

Direct Affinity Ligand Immobilization onto Bare Iron Oxide Nanoparticles Enables Efficient Magnetic Separation of Antibodies.

Magnetic separation is a promising alternative to chromatography for enhancing the downstream processing (DSP) of monoclonal antibodies (mAbs). However, there is a lack of efficient magnetic particles for successful application. Aiming to fill this gap, we demonstrate the suitability of bare iron oxide nanoparticles (BION) with physical site-directed immobilization of an engineered Protein A affinity ligand (rSpA) as an innovative magnetic material. The rSpA ligand contains a short peptide tag that enables the direct and stable immobilization onto the uncoated BION surface without commonly required laborious particle activation. The resulting BION@rSpA have beneficial characteristics outperforming conventional Protein A-functionalized magnetic particles: a simple, fast, low-cost synthesis, a particle size in the nanometer range with a large effective specific surface area enabling large immunoglobulin G (IgG) binding capacity, and a high magnetophoretic velocity advantageous for fast processing. We further show rapid interactions of IgG with the easily accessible rSpA ligands. The binding of IgG to BION@rSpA is thereby highly selective and not impeded by impurity molecules in perfusion cell culture supernatant. Regarding the subsequent acidic IgG elution from BION@rSpA@IgG, we observed a hampering pH increase caused by the protonation of large iron oxide surfaces after concentrating the particles in 100 mM sodium acetate buffer. However, the pH can be stabilized by adding 50 mM glycine to the elution buffer, resulting in recoveries above 85% even at high particle concentrations. Our work shows that BION@rSpA enable efficient magnetic mAb separation and could help to overcome emerging bottlenecks in DSP.

Recent advances in bio-based production of top platform chemical, succinic acid: an alternative to conventional chemistry.

Succinic acid (SA) is one of the top platform chemicals with huge applications in diverse sectors. The presence of two carboxylic acid groups on the terminal carbon atoms makes SA a highly functional molecule that can be derivatized into a wide range of products. The biological route for SA production is a cleaner, greener, and promising technological option with huge potential to sequester the potent greenhouse gas, carbon dioxide. The recycling of renewable carbon of biomass (an indirect form of CO2), along with fixing CO2 in the form of SA, offers a carbon-negative SA manufacturing route to reduce atmospheric CO2 load. These attractive attributes compel a paradigm shift from fossil-based to microbial SA manufacturing, as evidenced by several commercial-scale bio-SA production in the last decade. The current review article scrutinizes the existing knowledge and covers SA production by the most efficient SA producers, including several bacteria and yeast strains. The review starts with the biochemistry of the major pathways accumulating SA as an end product. It discusses the SA production from a variety of pure and crude renewable sources by native as well as engineered strains with details of pathway/metabolic, evolutionary, and process engineering approaches for enhancing TYP (titer, yield, and productivity) metrics. The review is then extended to recent progress on separation technologies to recover SA from fermentation broth. Thereafter, SA derivatization opportunities via chemo-catalysis are discussed for various high-value products, which are only a few steps away. The last two sections are devoted to the current scenario of industrial production of bio-SA and associated challenges, along with the author's perspective.

Novel method for production and purification of untagged pneumococcal surface protein A from clade 1.

Streptococcus pneumoniae can cause diseases with high mortality and morbidity. The licensed vaccines are based on capsular polysaccharides and induce antibodies with low cross reactivity, leading to restricted coverage of serotypes. For surpassing this limitation, new pneumococcal vaccines are needed for induction of broader protection. One important candidate is the pneumococcal surface protein A (PspA), which can be classified in 6 clades and 3 families. We have reported an efficient process for production and purification of untagged recombinant PspA from clade 4 (PspA4Pro). We now aim to obtain a highly pure recombinant PspA from clade 1 (PspA1) to be included, together with PspA4Pro, in a vaccine formulation to broaden response against pneumococci. The vector pET28a-pspA1 was constructed and used to transform Escherichia coli BL21(DE3) strain. One clone with high production of PspA1 was selected and adapted to high-density fermentation (HDF) medium. After biomass production in 6 L HDF using a bioreactor, the purification was defined after testing 3 protocols. During the batch bioreactor cultivation, plasmid stability remained above 90% and acetate formation was not detected. The final protein purification process included treatment with a cationic detergent after lysis, anion exchange chromatography, cryoprecipitation, cation exchange chromatography, and multimodal chromatography. The final purification process showed PspA1 purity of 93% with low endotoxin content and an overall recovery above 20%. The novel established process can be easily scaled-up and proved to be efficient to obtain a highly pure untagged PspA1 for inclusion in vaccine formulations. KEY POINTS: • Purification strategy for recombinant PspA1 from Streptococcus pneumoniae • Downstream processing for untagged protein antigens, the case of PspA1 • Purification strategy for PspA variants relies on buried amino acids in their sequences.

A roadmap towards manufacturing extracellular vesicles for cardiac repair.

For the past two decades researchers have linked extracellular vesicle (EV)-mediated mechanisms to various physiological and pathological processes in the heart, such as immune response regulation, fibrosis, angiogenesis, and the survival and growth of cardiomyocytes. Although use of EVs has gathered momentum in the cardiac field, several obstacles in both upstream and downstream processes during EV manufacture need to be addressed before clinical success can be achieved. Low EV yields obtained in small-scale cultures deter clinical translation, as mass production is a prerequisite to meet therapeutic doses. Moreover, standardizing EV manufacture is critical given the inherent heterogeneity of EVs and the constraints of current isolation techniques. In this review, we discuss the critical steps for the large-scale manufacturing of high-potency EVs for cardiac therapies.