Mycoplasmas and related bacteria in the class Mollicutes are parasitic organisms found not only on the external surfaces of a wide range of eukaryotic host cells, but also intracellularly. They are characterized by small size and lack of a rigid cell wall, which gives them resistance to β-lactam antibiotics and the ability to pass through 0.2-µm filters (1,2). Contamination by Mollicutes is a common problem for cell cultures that is not easily detected because it usually does not produce turbidity…
Analytical
Real-Time Bioreactor Monitoring of Osmolality and pH Using Near-Infrared Spectroscopy
Osmolality and pH are important cell culture process parameters, key elements that are often examined and optimized to improve the productivity of cell-culture–based bioprocesses. Osmolality affects cell viability and growth by regulating the transport of water and nutrients through cell membranes and pH maintains the isotonicity of a culture. To monitor these parameters in cell culture, samples are typically withdrawn and passed through a multifunction analyzer as the BioProfile 400 instrument from NOVA Biomedical (www.novabiomedical.com). Withdrawing samples during a bioreactor…
Encyclopedia of Rapid Microbiological Methods
Many different rapid microbiological methods (RMM) have been developed in recent years, although their acceptance and implementation in the pharmaceutical industry has been slow. To stimulate the integration of RMMs in the pharmaceutical industry, the Food and Drug Administration (FDA) introduced the Process Analytical Technology (PAT) initiative in 2004. A year later, the Encyclopedia of Rapid Microbiological Methods, edited by Michael J. Miller, was published. Miller, senior research fellow in the manufacturing and science department at Eli Lily, recruited many…
Use of Membrane Technology in Bioprocessing Therapeutic Proteins from Inclusion Bodies of
The ultimate goal of recombinant fermentation research is cost-effective production of desired proteins by maximizing volumetric productivity (to obtain the highest amount of protein in a given volume in the least amount of time). Bioprocessing for recombinant proteins using genetically modified organisms requires a stable, high-yielding recombinant culture, a highly productive fermentation process, and cost-effective recovery and purification procedures. Escherichia coli has been a widely used host for expression of recombinant proteins (1). Its advantages lie in the enormous data…
Medium and Process Optimization for High Yield, High Density Suspension Cultures: From Low Throughput Spinner Flasks to High Throughput Millilitre Reactors
The most important contributions to high-yield manufacturing processes for the production of recombinant proteins from cultivated mammalian cells have come from the identification of highly enriched and well-balanced media formulations, and fine tuning the process conditions that support high cell culture densities with high specific productivity. The industry standard yield for immunoglobulins or similar molecules derived from suspension-cultivated mammalian cells in bioreactors has risen during the past 20 years from the tens of mg/L to g/L. The more…
Rapid Purification of Lys-C from Cultures
Endoproteases specific for cleavage of peptidyl bonds on the C-terminal side of lysine residues (e.g., Lys-C) are produced from a number of bacterial species, including Achromobacter lyticus (1), Pseudomonas aeruginosa (2), and Lysobacter enzymogenes (3). The Achromobacter protease 1 (API) protein has been substantially characterized (4,5,6) and shown to be a resilient enzyme that can specifically cleave after lysine residues under a wide range of buffer conditions, including high concentrations of denaturing agents such as urea and sodium dodecyl sulphate…
Purifying a Recalcitrant Therapeutic Recombinant Protein with a Mixed-Mode Chromatography Sorbent
Mixed-mode chromatography sorbents can save time and money by reducing the number of steps required to purify recombinant proteins. They also have the potential to purify proteins that single-mode sorbents cannot. As the term mixed mode suggests, these sorbents contain ligands that offer multiple modes of interaction. Although mixed-mode sorbents are used extensively in solid-phase extraction for high-pressure liquid chromatography (HPLC) sample preparation — and to a more limited extent in analytical HPLC — these resins are generally unsuitable for…
MAb Contaminant Removal with a Multimodal Anion Exchanger
Monoclonal antibodies (MAbs) constitute ∼30% of the biopharmaceutical products currently under development (1). An increasing demand for MAbs during the past decade has led to intense development of high-expression cell cultures (2). Today, it is possible to see titers of 4–5 g/L, and expression levels as high as 15 g/L and greater have been reported. As a consequence, demand has increased for more efficient downstream processes. That demand, combined with its potential for reducing time-to-market, has increased interest in the…
The Reoccurrence of Mycoplasma Contamination: Prevention Strategies
The contamination of microbiological media by mycoplasmas such as Acholeplasma laidlawii is not a recent phenomenon. It has been a major problem with animal-derived sera since the 1980s and has been a concern in the management of cell cultures for decades. The main culprit of serum contamination was the inadequate blood collection methodology and was eliminated with the introduction of hollow collection needles. In addition to the introduction of an improved collection method, serum was filtered with 0.1…
Robustness of Parvovirus–Retentive Membranes and Implications for Virus Clearance Validation Requirements
Generic validation is conceivable only through a thorough understanding of the parameters affecting the performance of a process step. In this paper, we provide a detailed example demonstrating the robustness of a virus filtration step. As a first step towards the establishment of a generic validation package for a monoclonal antibody, the robustness of clearance of PP7 across the ViroSart CPV filter was evaluated by changing several critical operational parameters using a simple one-off experimental design. Two different…