Re-use of spent cell culture medium in pilot scale and rapid preparative purification with membrane chromatography

Sustainable media feedstocks for cellular agriculture

The global food system is shifting towards cellular agriculture, a second domestication marked by cultivating microorganisms and tissues for sustainable food production. This involves tissue engineering, precision fermentation, and microbial biomass fermentation to establish food value chains independent of traditional agriculture. However, these techniques rely on growth media sourced from agricultural, chemical (fossil fuels), and mining supply chains, raising concerns about land use competition, emissions, and resource depletion. Fermentable sugars, nitrogen, and phosphates are key ingredients derived from starch crops, energy-intensive fossil fuel based processes, and finite phosphorus resources, respectively. This review explores sustainable alternatives to reduce land use and emissions associated with cellular agriculture media ingredients. Sustainable alternatives to first generation sugars (lignocellulosic substrates, sidestreams, and gaseous feedstocks), sustainable nitrogen sources (sidestreams, green ammonia, biological nitrogen fixation), and efficient use of phosphates are reviewed. Especially cellulosic sugars, gaseous chemoautotrophic feedstocks, green ammonia, and phosphate recycling are the most promising technologies but economic constraints hinder large-scale adoption, necessitating more efficient processes and cost reduction. Collaborative efforts are vital for a biotechnological future grounded in sustainable feedstocks, mitigating competition with agricultural land and emissions.

Advances and Challenges in Cell Biology for Cultured Meat

Cultured meat is an emerging biotechnology that aims to produce meat from animal cell culture, rather than from the raising and slaughtering of livestock, on environmental and animal welfare grounds. The detailed understanding and accurate manipulation of cell biology are critical to the design of cultured meat bioprocesses. Recent years have seen significant interest in this field, with numerous scientific and commercial breakthroughs. Nevertheless, these technologies remain at a nascent stage, and myriad challenges remain, spanning the entire bioprocess. From a cell biological perspective, these include the identification of suitable starting cell types, tuning of proliferation and differentiation conditions, and optimization of cell-biomaterial interactions to create nutritious, enticing foods. Here, we discuss the key advances and outstanding challenges in cultured meat, with a particular focus on cell biology, and argue that solving the remaining bottlenecks in a cost-effective, scalable fashion will require coordinated, concerted scientific efforts. Success will also require solutions to nonscientific challenges, including regulatory approval, consumer acceptance, and market feasibility. However, if these can be overcome, cultured meat technologies can revolutionize our approach to food.

Conversion of mammalian cell culture media waste to microbial fermentation feed efficiently supports production of recombinant protein by Escherichia coli

Deriving new value from waste streams through secondary processes is a central aim of the circular bioeconomy. In this study we investigate whether chemically defined spent media (CDSM) waste from cell culture bioprocess can be recycled and used as a feed in secondary microbial fermentation to produce new recombinant protein products. Our results show that CDSM supplemented with 2% glycerol supported a specific growth rate of E. coli cultures equivalent to that achieved using a nutritionally rich microbiological media (LB). The titre of recombinant protein produced following induction in a 4-hour expression screen was approximately equivalent in the CDSM fed cultures to that of baseline, and this was maintained in a 16-hr preparative fermentation. To understand the protein production achieved in CDSM fed culture we performed a quantitative analysis of proteome changes in the E. coli using mass spectrometry. This analysis revealed significant upregulation of protein synthesis machinery enzymes and significant downregulation of carbohydrate metabolism enzymes. We conclude that spent cell culture media, which represents 100s of millions of litres of waste generated by the bioprocessing industry annually, may be valorized as a feed resource for the production of recombinant proteins in secondary microbial fermentations. Data is available via ProteomeXchange with identifier PXD026884.

Current evidence in high throughput ultrafiltration toward the purification of monoclonal antibodies (mAbs) and biotechnological protein-type molecules

Pressure-driven membrane-based technologies, such as microfiltration (MF), ultrafiltration (UF), and nanofiltration (NF), have been successfully implemented in recovering different types of biomolecules and high-value-added compounds from various streams. Especially, UF membranes meet the requirements for separating specific bioproducts in downstream processes, e.g. monoclonal antibodies (mAbs), which are recognized as proteins produced mainly by plasma cells. According to the importance and functionality of the mAbs, their recovery is a current challenge with these bioseparations. Nevertheless, mAbs recovery using UF-assisted processes has been smartly performed over the last decade. To the best of our knowledge, there are no reviews of the reported developments using UF technology toward mAbs separation. Therefore, the goal of this paper is to collect and elucidate ongoing research studies implemented for the featured separation of mAbs and other biotechnological protein-type molecules (e.g. adenovirus serotype, extracellular vesicles, red fluorescent protein, cyanovirin-N, among others) via ultrafiltration-aided systems. The literature evidence (e.g. research papers, patents, etc.) has been analyzed and discussed according to the purpose of the study. Importantly, the relevant findings and novel approaches are discussed in detail. To finalize this document, the advantages, drawbacks, and guidelines in applying membrane-based techniques for such a recovery are presented.

The use of peptones as medium additives for the production of a recombinant therapeutic protein in high density perfusion cultures of mammalian cells

Protein hydrolysates as substitutes for serum havebeen employed by many in cell culture mediumformulation, especially with the shift to low proteinor protein-free media. More recently, vegetablehydrolysates have also been added as nutritionalsupplements to fortify the amino acid content in smallpeptide form for batch and fed-batch fermentations. Several of these new hydrolysates (peptones of soy,rice, wheat gluten etc.) were tested as protein-freemedium supplements for the production of a recombinanttherapeutic protein. Multiple peptone-supplemented,continuous perfusion bioreactor experiments wereconducted, varying dilution rates and basal mediumcomposition over the various runs. Cell specificrates and product quality studies were obtained forthe various peptones and compared with peptone-freemedium. The potential for peptones to decreaseintrinsic and proteolytic degradation of the productwas also investigated.It was found that peptones confer a nutritionalbenefit, especially at low dilution rates, for therecombinant BHK cell line used in this investigation.The specific productivity increased 20-30% comparedto the peptone-free controls. However, this benefitwas also fully delivered by using fortified medium inplace of the peptone-enriched media. Therefore, whilepeptones may be considered as useful medium additiveswhen development time is limited, their addition maybe avoided by systematic medium development ifpermitted by the time line of the project.

Large-scale production of pharmaceuticals by marine sponges: sea, cell, or synthesis?

Marine sponges are known to produce an overwhelming array of secondary metabolites with pharmaceutical potential. The technical and economical potential of using marine sponges for large-scale production of these compounds was assessed for two cases: the anticancer molecule halichondrin B from a Lissodendoryx sp., and avarol from Dysidea avara for its antipsoriasis activity. An economic and technical analysis was done for three potential production methods: mariculture, ex situ culture (in tanks), and cell culture. We concluded that avarol produced by mariculture or ex situ culture could become a viable alternative to currently used pharmaceuticals for the treatment of psoriasis. Production of halichondrin B from sponge biomass was found to not be a feasible process, mainly due to the extremely low concentration of the compound in the sponge. Technical feasibility was also analyzed for five alternatives: chemical synthesis, wild harvest, primmorph culture, genetic modification and semi-synthesis. It was concluded that the latter two approaches could prove to be valuable methods for the production of pharmaceuticals, based on chemical structures of secondary metabolites present in trace amounts in marine sponges.

Progress in monitoring, modeling and control of bioprocesses during the last 20 years

The paper gives a review on the recent development of bioprocess engineering. It includes monitoring of product formation processes by flow injection analysis, various types of chromatographic and spectroscopic methods as well as by biosensors. The evaluation of mycelial morphology and physiology by digital image analysis is discussed also. It deals with advanced control of indirectly evaluated process variables by means of state estimation/observer, with the use of structured and hybrid models, expert systems and pattern recognition for process optimization and gives a short report on the state of the art of metabolic flux analysis and metabolic engineering.

Membrane ion-exchange chromatography for process-scale antibody purification

The large-scale production of recombinant monoclonal antibodies demands economical purification processes with high throughputs. The potential for ion-exchange membrane adsorbers to replace traditional ion-exchange columns was evaluated. Breakthrough capacities of commercially available cation-exchange membranes were determined as a function of flow-rate and layer number. Due to economic and process restrictions, cation-exchange membranes may not currently be advantageous for process-scale antibody purification in a bind and elute mode. However, anion-exchange membranes in a flow-through mode may provide a reasonable alternative to columns for the removal of low levels of impurities such as DNA, host cell protein, and virus.

Hybridoma growth and productivity: effects of conditioned medium and of inoculum size

Apart from gas concentrations, temperature, and pH, generally only the initial conditions can be manipulated in batch culture. Inoculum size and initial conditioned medium concentration represent two important considerations for optimal batch production. Two hybridoma cell lines were used to assess the impact of these initial conditions on population growth and monoclonal antibody productivity in suspension batch culture. Varying initial cell concentration over the range of 1.0 x 105 cells mL-1 to 3.0 x 105 cells mL-1 did not affect maximum product titre or maximum volumetric cell-hours attained. Initial percent of conditioned medium up to 40 percent strongly impacted on population growth and productivity, with initial levels of 30 to 40% conditioned medium reducing or eliminating lag phase and increasing average viable cell density. However, specific productivity and product titre declined with increasing initial percent conditioned medium, even on a per volume of fresh medium basis. Glutamine and glucose depletion or ammonia toxicity could cause depressed product titres when conditioned medium is used. Glutamine and glucose levels can easily be replenished in conditioned medium at minimal cost, and ammonia can be removed. Specific productivity was higher during cyclic batch operating mode than during batch operating mode. This may be because cyclic batch operating mode results in an incidental volume of conditioned medium at the beginning of each cycle. A two stage, cyclic-batch/batch operating mode can be employed to fully utilize medium and maximize product titre.

Separation of paraproteins from human plasma by membrane chromatography

Membrane chromatography using a commercially available blotting membrane was performed in a dead-end filtration mode to separate paraproteins from plasma of patients suffering from paraproteinemia. The affinity membrane was found to display distinct specificity to monoclonal IgG1. A dissociation constant (Kd) of 3.2 microM and a maximum binding capacity of 1.43 mg/cm2 IgG1 paraprotein were obtained from the adsorption isotherm of the affinity membrane. The membrane was found to absorb immunoglobulins species-dependently because no binding of immunoglobulins from mouse, rat and rabbit could be observed.

The Super-Spinner: a low cost animal cell culture bioreactor for the CO2 incubator

The production of small quantities of monoclonal antibodies and recombinant proteins was carried out using a new low cost production system, the Super Spinner. Into a 1 1 standard Duran flask a membrane stirrer equipped with a polypropylene hollow fiber membrane was installed to improve the oxygen supply by bubble-free aeration. The aeration was facilitated by using the CO2 conditioned incubator gas, which was pumped through the membrane stirrer via a small membrane pump. The maximal oxygen transfer rate (OTRmax) of the Super Spinner was detected. For this purpose one spinner flask was equipped with an oxygen electrode. The OTRmax was measured by the dynamic method. The ratio of membrane length to culture volume was adapted corresponding to the oxygen uptake rate of the cells according to the desired cell density. A balanced nutrient supply resulted in an optimal formation and yield of products.