The importance and future of biochemical engineering.

Today's Biochemical Engineer may contribute to advances in a wide range of technical areas. The recent Biochemical and Molecular Engineering XXI conference focused on "The Next Generation of Biochemical and Molecular Engineering: The role of emerging technologies in tomorrow's products and processes". On the basis of topical discussions at this conference, this perspective synthesizes one vision on where investment in research areas is needed for biotechnology to continue contributing to some of the world's grand challenges.

Design-for-Six-Sigma To Develop a Bioprocess Knowledge Management Framework.

Owing to the high costs associated with biopharmaceutical development, considerable pressure has developed for the biopharmaceutical industry to increase productivity by becoming more lean and flexible. The ability to reuse knowledge was identified as one key advantage to streamline productivity, efficiently use resources, and ultimately perform better than the competition. A knowledge management (KM) strategy was assembled for bioprocess-related information using the technique of Design-for-Six-Sigma (DFSS). This strategy supported quality-by-design and process validation efforts for pipeline as well as licensed products. The DFSS technique was selected because it was both streamlined and efficient. These characteristics permitted development of a KM strategy with minimized team leader and team member resources. DFSS also placed a high emphasis on the voice of the customer, information considered crucial to the selection of solutions most appropriate for the current knowledge-based challenges of the organization. The KM strategy developed was comprised of nine workstreams, constructed from related solution buckets which in turn were assembled from the individual solution tasks that were identified. Each workstream's detailed design was evaluated against published and established best practices, as well as the KM strategy project charter and design inputs. Gaps and risks were identified and mitigated as necessary to improve the robustness of the proposed strategy. Aggregated resources (specifically expense/capital funds and staff) and timing were estimated to obtain vital management sponsorship for implementation. Where possible, existing governance and divisional/corporate information technology efforts were leveraged to minimize the additional bioprocess resources required for implementation. Finally, leading and lagging indicator metrics were selected to track the success of pilots and eventual implementation. LAY ABSTRACT: A knowledge management framework was assembled for bioprocess-related information using a streamlined and efficient technique that minimized team leader and member resources. The technique also highly emphasized input from the staff, who generated and used the knowledge, information considered crucial to selection of solutions most appropriate for the current knowledge-based challenges in the organization. The framework developed was comprised of nine workstreams, constructed from related solution buckets which were assembled from individual solution tasks that were identified. Each workstream's detailed design was evaluated against published and established best practices, as well as the project charter and design inputs. Gaps and risks were identified and mitigated to improve robustness of the proposed framework. Aggregated resources (specifically expense/capital funds and staff) and timing were estimated to obtain vital management sponsorship for implementation. Where possible, existing governance and information technology efforts were leveraged to minimize additional bioprocess resources required for implementation. Finally, metrics were selected to track the success of pilots and eventual implementation.

Design-for-Six-Sigma for Development of a Bioprocess Quality-by-Design Framework.

An initial quality-by-design (QbD) framework was assembled for biopharmaceutical product, process, and analytical development using the design-for-six-sigma (DFSS) methodology. This technique was both streamlined and efficient, which permitted development of a QbD framework with minimized team leader and member resources. DFSS also highly emphasized voice-of-the-customer, information considered crucial to development and implementation of a bioprocess QbD framework appropriate for current development needs of the organization and its regulatory environment. The bioprocess QbD final design and implementation plan was comprised of seven teams, constructed from six QbD elements plus a communication/training team. Each element's detailed design was evaluated against internal and external established best practices, the QbD charter, and design inputs. Gaps were identified and risks mitigated to assure robustness of the proposed framework. Aggregated resources and timing were estimated to obtain vital implementation sponsorship. Where possible, existing governance and information technology efforts were leveraged to minimize additional bioprocess resources required. Finally, metrics were selected to track success of pilots and eventual implementation. LAY ABSTRACT: An initial quality-by-design (QbD) framework was assembled to guide biopharmaceutical product, process, and analytical development. QbD starts by defining the patient requirements which then are translated into required quality attributes for the product. The production process then is designed to consistently meet these quality requirements by identifying and understanding those parameters which influence them. A control strategy is developed that specifically relates each point of control to a desired quality measure. Overall, this approach results in a robust process, capable of reliably producing quality product. The bioprocess QbD framework was developed to guide implementation of the desired QbD strategy. It was comprised of seven teams, constructed from six QbD elements plus a communication/training team. Each element's detailed design was evaluated against internal and external established best practices, the charter, and design inputs. Gaps were identified and risks mitigated to assure robustness of the proposed framework. Aggregated resources and timing were estimated to obtain vital implementation sponsorship. Where possible, existing governance and information technology efforts were leveraged to minimize additional bioprocess resources required. Finally, metrics were selected to track success of pilots and eventual implementation.

Industrial bioprocesses: beyond routine applications of established methodologies.

The subject matter of manuscripts by industrial authors has primarily focused on elements with perceived commercial or regulatory significance. Once published, this information interacted and ultimately influenced manuscripts from authors of other affiliations, creating the rapid advancements that culminated in the current multi-billion dollar worldwide biotechnology industry. This paper discusses trends in "solely industrial" articles published in the specific journal of Biotechnology and Bioengineering over the past five decades of this journal's lifetime. "Solely industrial" articles were defined as papers in which all the authors were affiliated with industry. Data were gathered concerning "solely industrial" article distribution and frequency, authoring companies, subject classification, and category distribution. Selected articles and their impact were related to current and past technology milestones as well as associated challenges. Suggestions for areas of greater emphasis to influence the number and subject matter of "solely industrial" articles for the journal's sixth decade were offered for consideration.

Actinomycetes scale-up for the production of the antibacterial, nocathiacin.

An Amycolatopsis fastidiosa culture, which produces the nocathiacin class of antibacterial compounds, was scaled up to the 15,000 L working volume. Lower volume pilot fermentations (600, 900, and 1,500 L scale) were conducted to determine process feasibility at the 15,000 L scale. The effects of inoculum volume, impeller tip speed, volumetric gas flow rate, superficial gas velocity, backpressure, and sterilization heat stress were examined to determine optimal scale-up operating conditions. Inoculum volume (6 vs. 2 vol %) and medium sterilization (R(o) of 68 vs. 92 min(-1)) had no effect on productivity or titer, and higher impeller tip speeds (2.1 vs. 2.9 m/s) had a slight effect (20% decrease). In contrast, higher backpressure, incorporating increased head pressure at the 15,000 L scale (1.2 vs. 0.7 kg/cm(2)) and low gas flow rates (0.25 vs. 0.8 vvm), appeared to be problematic (40-50% decrease). High off-gas CO2 levels were likely reasons for observed lower productivity. Consequently, air flow rate for this 25-fold scale-up (600-15,000 L) was controlled to match off-gas CO2 profiles of acceptable smaller scale batches to maintain levels below 0.5%. The 15,000 L-scale fermentation achieved an expected nocathiacin I titer of 310 mg/L after 7 days. Other on-line data (i.e., pH, oxygen uptake rate, and CO2 evolution rate) and off-line data (i.e., analog production, glucose utilization, ammonium production, and dry cell weight) at the 15,000 L scale also tracked similarly to the smaller scale, demonstrating successful fermentation scale-up.

Pilot-scale process development and scale up for antifungal production.

A pilot-scale fermentation was developed for an antifungal compound produced by a filamentous fungus. Replacement of galactose with lactose (20-fold cost savings) and a threefold phosphate reduction (15 to 5 g/L) improved productivity 2.5-fold. Addition of supplements--glycine, cobalt chloride, and trace elements--resulted in a further twofold productivity increase, greater process robustness, and less foaming which reduced antifoam addition tenfold (30 to <3 mL/L). Mid-cycle lactose limitations were addressed by raising initial lactose levels (40 to 120 g/L) resulting in another twofold productivity increase. Overall, peak titers increased tenfold from 45 +/- 9 to 448 +/- 39 mg/L, and productivities improved from 3 to 25 mg/L day. Despite its high productivity, process scale up was challenged by high broth viscosity (5,000-6,000 cP at 16.8 s(-1)). Gassed power requirements at the 600 L scale (4.7 kW/1,000 L) exceeded available power at the 15,000 L scale (3.0 kW/1,000 L), and broth transfer to the downstream isolation facility was hindered. Mid-cycle broth dilution with up to five 10 vol% additions of 12 wt% lactose solution or whole medium-reduced viscosity three- to fivefold (1,000-1,500 cP at 16.8 s(-1)), gassed power within scale-up limits (2.5 kW/1,000 L), and peak titer by up to 45%. The process was scaled up to the 15,000 L working volume based on constant aeration rate (vvm) and peak impeller tip speed, raising superficial velocities at similar shear. This strategy maximized mass transfer rates at target gassed power per unit volume levels, and along with controlled broth viscosity, precluded multiple dilution additions. A final titer of 333 mg/L with one dilution addition was achieved, somewhat lower than expected, likely owing to inhibition from some unmeasured volatile compound (not believed to be carbon dioxide) during an extended period of high back-pressure in the early production phase.

Corrosion in bioprocessing applications.

Corrosion in bioprocessing applications is described for a 25-year-old bioprocessing pilot plant facility. Various available stainless steel alloys differ greatly in properties owing to the impact of specific alloying elements and their concentrations. The alloy property evaluated was corrosion resistance as a function of composition under typical bioprocessing conditions such as sterilization, fermentation, and cleaning. Several non-uniform forms of corrosion relevant to bioprocessing applications (e.g., pitting, crevice corrosion, intergranular attack) were investigated for their typical causes and effects, as well as alloy susceptibility. Next, the corrosion resistance of various alloys to specific bioprocessing-relevant sources of corrosion (e.g., medium components, acids/bases used for pH adjustment, organic acid by-products) was evaluated, along with the impact of temperature on corrosion progression. Best practices to minimize corrosion included considerations for fabrication (e.g., welding, heat treatments) and operational (e.g., sterilization, media component selection, cleaning) approaches. Assessments and repair strategies for observed corrosion events were developed and implemented, resulting in improved vessel and overall facility longevity.

Isolation and structure elucidation of thiazomycin- a potent thiazolyl peptide antibiotic from Amycolatopsis fastidiosa.

Thiazolyl peptides are a class of rigid macrocyclic compounds richly populated with thiazole rings. They are highly potent antibiotics but none have been advanced to clinic due to poor aqueous solubility. Recent progress in this field prompted a reinvestigation leading to the isolation of a new thiazolyl peptide, thiazomycin, a congener of nocathiacins. Thiazomycin possesses an oxazolidine ring as part of the amino-sugar moiety in contrast to the dimethyl amino group present in nocathiacin I. The presence of the oxazolidine ring provides additional opportunities for chemical modifications that are not possible with other nocathiacins. Thiazomycin is extremely potent against Gram-positive bacteria both in vitro and in vivo. The titer of thiazomycin in the fermentation broth was very low compared to the nocathiacins I and III. The lower titer together with its sandwiched order of elution presented significant challenges in large scale purification of thiazomycin. This problem was resolved by the development of an innovative preferential protonation based one- and/or two-step chromatographic method, which was used for pilot plant scale purifications of thiazomycin. The isolation and structure elucidation of thiazomycin is herein described.

Foam and its mitigation in fermentation systems.

Key aspects of foaming and its mitigation in fermentation systems are presented. Foam properties and behavior, conditions that affect foaming, and consequences of foaming are discussed, followed by methods to detect and prevent foam, both without and with the use of antifoam, and their implications. Antifoams were catalogued according to their class (e.g., polyalkylene glycols, silicone emulsions, etc.) to facilitate recognition of antifoams possessing similar base compositions. Relatively few published studies directly comparing antifoams experimentally are available, but those reports found only partially identify clear benefits/disadvantages of any one antifoam type. Consequently, desired characteristics, trends in antifoam application, and chemical types of antifoams are evaluated on the basis of a thorough review of available literature reports describing a specific antifoam's usage. Finally, examples of specific foaming situations taken from both the literature and from actual experience in an industrial fermentation pilot plant are examined for their agreement with expected behavior.

Feasibility of an in situ measurement device for bubble size and distribution.

The feasibility of in situ measurement device for bubble size and distribution was explored. A novel in situ probe measurement system, the EnviroCam, was developed. Where possible, this probe incorporated strengths, and minimized weaknesses of historical and currently available real-time measurement methods for bubbles. The system was based on a digital, high-speed, high resolution, modular camera system, attached to a stainless steel shroud, compatible with standard Ingold ports on fermenters. Still frames and/or video were produced, capturing bubbles passing through the notch of the shroud. An LED light source was integral with the shroud. Bubbles were analyzed using customized commercially available image analysis software and standard statistical methods. Using this system, bubble sizes were measured as a function of various operating parameters (e.g., agitation rate, aeration rate) and as a function of media properties (e.g., viscosity, antifoam, cottonseed flour, and microbial/animal cell broths) to demonstrate system performance and its limitations. For selected conditions, mean bubble size changes qualitatively compared favorably with published relationships. Current instrument measurement capabilities were limited primarily to clear solutions that did not contain large numbers of overlapping bubbles.

Sustainable reduction of bioreactor contamination in an industrial fermentation pilot plant.

Facility experience primarily in drug-oriented fermentation equipment (producing small molecules such as secondary metabolites, bioconversions, and enzymes) and, to a lesser extent, in biologics-oriented fermentation equipment (producing large molecules such as recombinant proteins and microbial vaccines) in an industrial fermentation pilot plant over the past 15 years is described. Potential approaches for equipment design and maintenance, operational procedures, validation/verification testing, medium selection, culture purity/sterility analysis, and contamination investigation are presented, and those approaches implemented are identified. Failure data collected for pilot plant operation for nearly 15 years are presented and best practices for documentation and tracking are outlined. This analysis does not exhaustively discuss available design, operational and procedural options; rather it selectively presents what has been determined to be beneficial in an industrial pilot plant setting. Literature references have been incorporated to provide background and context where appropriate.

Measurement of bubble and pellet size distributions: past and current image analysis technology.

Measurements of bubble and pellet size distributions are useful for biochemical process optimizations. The accuracy, representation, and simplicity of these measurements improve when the measurement is performed on-line and in situ rather than off-line using a sample. Historical and currently available measurement systems for photographic methods are summarized for bubble and pellet (morphology) measurement applications. Applications to cells, mycelia, and pellets measurements have driven key technological developments that have been applied for bubble measurements. Measurement trade-offs exist to maximize accuracy, extend range, and attain reasonable cycle times. Mathematical characterization of distributions using standard statistical techniques is straightforward, facilitating data presentation and analysis. For the specific application of bubble size distributions, selected bioreactor operating parameters and physicochemical conditions alter distributions. Empirical relationships have been established in some cases where sufficient data have been collected. In addition, parameters and conditions with substantial effects on bubble size distributions were identified and their relative effects quantified. This information was used to guide required accuracy and precision targets for bubble size distribution measurements from newly developed novel on-line and in situ bubble measurement devices.

Scale-up methodologies for Escherichia coli and yeast fermentation processes.

Scale-up techniques from the literature have been compiled and reviewed for applicability to Escherichia coli and yeast processes. The consistency of design and operating parameters for the pilot scale vessels in an existing fermentation pilot plant, ranging in nominal volume from 100 l to 19,000 l, was established and compared favorably with approaches found in the literature. Differences were noted as a function of parameters such as fermentor scale, vessel geometry, agitator type/size and ungassed/gassed power input. Further analysis was conducted using actual fermentation data for historical and recent development processes collected over a 10-year-period, focussing on operating conditions at peak culture oxygen uptake rates. Scale-up estimates were performed based on geometric similarity, agitator tip speed, gassed power per unit volume and mixing time. Generally, scale-up calculations from the 280 l scale were most similar to the parameters of installed equipment. Scale-up from the 30 l laboratory scale typically underpredicted parameters with scale-up from the 280 l scale being most appropriate. The 19,000 l fermentor installation was notably different in geometric similarity from the 280 l-1900 l scales since its design was meant to accommodate a wide range of operating volumes. Analysis of historical and recent processing performance was conducted for single cell bacterial or yeast fermentations which challenged peak operating conditions of the fermentors. Identification of key issues associated with scale-up for these specific pilot plant vessels was believed to be critical to efficient process development, clinical material production, and expected process transfer to a manufacturing facility.

Use of glucose feeding to produce concentrated yeast cells.

A defined medium and fed-batch feeding process for the production of a yeast biocatalyst, developed at the 23-L scale, was scaled up to the 600-L pilot scale. Presterilized 100-L-vol plastic bags were implemented for the pilot-scale nutrient feeding. Medium of increased concentration Oqs implemented at the pilot scale, and equivalent dry cell weights were reached with a medium 80% more concentrated than that used at the laboratory scale. The higher medium concentration was believed to be necessary at the pilot scale owing to the additional heat stresses on key components (e.g., complexing of magnesium sulfate with phosphate), increased dilution during sterilization, lower evaporation rate owing to the lower vessel volume per minute air flow rate, and increased dilution owing to nutrient feeding or shot additions. Peak cell density was found to be somewhat insensitive to variations in residual glucose levels. These results suggest that defined medium developed at the laboratory scale may need to be further optimized at the pilot scale for equivalent performance.