Advanced Bioprocess Engineering INTRODUCTION Lecturer Dr. Kamal E. M. Elkahlout Assistant Prof. of Biotechnology Relationship of Scientists Engineers • Microbiologists, biochemists, and molecular biologists are scientists, well-trained in empirical testing of hypotheses. • Engineers develop theories based on mathematical models, use models to predict performance, optimize and develop processes. Biologists and Engineers • Research scientists often pursue knowledge while applications may take a secondary role. • The work of engineers is often driven by economics of an application and problem solving. • A bioprocess is any process that uses complete living cells or their components (e.g., bacteria, enzymes, chloroplasts) to obtain desired products • Transport of energy and mass is fundamental to many biological and environmental processes. • Areas, from food processing to thermal design of building to biomedical devices to pollution control and global warming, require knowledge of how energy and mass can be transported through materials[mass,momentum,heat transfer] Bioprocess Engineering • It is a specialization of Biotechnology, Chemical Engineering or of Agricultural Engineering. • It deals with the design and development of equipment and processes for the manufacturing of products such as food, feed, pharmaceuticals, nutraceuticals, chemicals, and polymers and paper from biological materials. • Bioprocees engineering is a conglomerate of mathematics, biology and industrial design, • It consists of various spectrums like designing of Fermentors, study of fermentors (mode of operations etc). • It also deals with studying various biotechnological processes used in industries for large scale production of biological product for optimization of yield in the end product and the quality of end product. • Bio process engineering may include the work of mechanical, electrical, and industrial engineers to apply principles of their disciplines to processes based on using living cells or sub component of such cells. Definition of Fermentation • Metabolism: energy generating processes where organic compound acts as both electron donor and acceptor. • Industrial Biotechnology: the process by which large quantities of cells are grown under aerobic or anaerobic conditions. • The industrial microorganisms are grown under controlled conditions with an aim of optimizing the growth of the organism for production of a target microbial product. Definition of Fermentation • Fermentation is carried out in vessels known as Fermentors • The types of fermentor ranges from simple tank to complex integrated system of automated control. An overview of a typical industrial fermentation process and the movement of materials through a typical fermentation plant are shown in the following figure: Fermentation Plant The Process of Fermentation • Process is divided into a number of sections: • · In-bound logistics: (the delivery and storage of raw materials) • · Upstream processing: the processing of raw materials for the fermentation • · The fermentation, where the major conversion occurs • · Downstream processing: the purification and concentrating of the raw product(s) • · Out-bound logistics : the final packaging, storage and delivery of the purified product(s) • Stages of Industrial fermentation: • · Upstream Processing (USP) • · Downstream Processing (DSP) Upstream Processing • The upstream part of a bioprocess refers to the first step in which microbes/cells are grown, eg bacterial or mammalian cell lines (see Cell culture), in bioreactors. • Basically upstream processing involve all those steps related with inoculum development, media development, improvement of inoculum by genetic engineering process, optimization of growth kinetics so that product development can improve tremendously. • Fermentation has two part upstream & downstream. • After product development the next step is purification of product for desired quality. • When they reach the desired density (for batch and fed batch cultures) they are harvested and moved to the downstream section of the bioproces Upstream Processing • • • • • • • • • Three main areas: A) Producer microorganism This include processes for obtaining a suitable microorganism strain improvement to increase the productivity and yield maintenance of strain purity preparation of suitable inocullum B ) Fermentation media C) Fermentation Process Downstream Processing • The downstream part of a bioprocess refers to the part where the cell mass from the upstream are processed to meet purity and quality requirements. • Downstream processing is usually divided into three main sections, • a capture section, • a purification section and • a polishing section. • The volatile products can be separated by distillation of the harvested culture without pre-treatment. • Distillation is done at reduced pressure at continuous stills. • At reduced pressure distillation of product directly from fermentor may be possible. • The steps of downstream processing are: • • • • • • • 1-separation of biomass 2-cell disruption 3-concentration of broth 4-initial purification of metabolites 5-metabolite specific purification 6-de-watering 7-polishing of metabolites • 1-separation of biomass: separating the biomass (microbial cells) generally carried out by centrifugation or ultra-centrifugation. If the product is biomass, then it is recovered for processing and spent medium is discarded. If the product is extra cellular the biomass will be discarded.Ultra filtration is an alternative to the centrifugation. 2-cell disruption: If the desired product is intra cellular the cell biomass can be disrupted so that the product should be released. The solid-liquid is separated by centrifugation or filtration and cell debris are discarded. • • 3-concentration of broth: The spent medium is concentrated if the product is extracellular. • 4-initial purification of metabolites: According to the physico-chemical nature of the product molecule several methods for recovery of product from the clarified fermented broth were used ( precipitation, solvent extraction, ultra-centrifugation, ionexchange chromatography, adsorption and solvent extraction) • 5-metabolite specific purification: specific purification methods are used when the desired metabolite is purified to a very high degree. • 6-de-watering: If low amount of product is found in very large volume of spent medium, the volume is reduced by removing water to concentrate the product. It is done by vacuum drying or reverse osmosis. • 7-polishing of metabolites: this is the final step of making the product to 98 to 100% pure.the purified product is mixed with several inert ingredients called EXCIPIENTS. the formulated product is packed and sent to the market for the consumers. • Types of Fermentation Process • • • • Batch Fermentation Continuous Fermentation Fed batch Batch reactors ,simplest type. Reactor is filled with medium and the fermentation is allowed. • Fermentation has finished, contents are emptied for downstream processing. • The reactor is then cleaned, re-filled, re-inoculated and the fermentation process starts again. Types of Fermentation Process • Continuous reactors, where fresh media is continuously added and bioreactor fluid is continuously removed. • As a result, cells continuously receive fresh medium and products and waste products and cells are continuously removed for processing. • The reactor can thus be operated for long periods of time without having to be shut down. • Many times more productive than batch reactors. Types of Fermentation Process • does not have to be shut down as regularly • the growth rate of the bacteria in the reactor can be more easily controlled and optimized • cells can also be immobilized in continuous reactors, to prevent their removal. • Fed batch reactor, most common type of reactor used in industry. • fresh media is continuous or sometimes periodically added. Batch Fermentation Process • dynamic processes that are never in a steady state. • Often , the critical parameter is gas exchange or balance between respiration rate and oxygen transfer. • sterilized media components are supplied at the beginning of the fermentation with no additional feed after inoculation. Batch Fermentation Process • cells are grown in a batch reactor, they go through a series of stages: • Lag phase • · Exponential phase • · Stationary phase • · Death phase Batch Fermentation Process Batch Fermentation Process • Lag Phase • microbial population remains constant as there is no growth. However it is the period of intense metabolic activity. • Factors Influencing the Lag Phase • · Chemical composition of the fermentation media influences the length of the lag phase. • Longer lag phase is observed if the inocullum is transferred into a fresh medium of different carbon source. • · Age of the inocullum. If the inocullum is in exponential growth phase, it will exhibit shorter lag in the fresh medium. • · Concentration of the inocullum. • · Viability and morphology of the inocullum. Penicillin: “Birth of Biochemical Engineering” • 1928- Alexander Flemming was plating Staphylococcus aureus and the plate was contaminated with mold – near the mold no bacteria grew. • WWII- most common cause of death was infection from wounds. • Sulfa drugs were effective on limited range of infectious organisms. • 1930-1940 British scientists Florey and Chain at Oxford developed a process to produce penicillin from the mold. How Penicillin Works... Antibiotics on a plate: cell walls do not form Early Work • They asked US pharmaceutical companies to help work on the project – to develop a commercial scale process for penicillium. • Merck, Pfizer, Squibb, USDA • At this time, most drugs were made synthetically. Fermentation was unproved and companies were skeptical. • Problem: low concentrations, fragile product. Significant Advances • New medium- Corn steep liquor (x10). • New strain isolated from molded fruit- P. chrysogenum (still used in some form). • Change to tanks from “bottle plants”. • Separation: liquid-liquid extraction. Challenges • Very large (10 kgal) fermentation vessels. • Provide sterile air and feed. • Agitator seal. • Heat removal. • Recovery and purification of fragile product. Biology-Engineering Connection • Cooperation between engineers and scientists was critical (Merck specifically formed teams of each). • “Biochemical engineering” born as a result. • • Essential Knowledge/ Topics needed in Bioprocess engineering work • – Cells • – How cells work • – Metabolism Pathways • – Enzymes and Kinetics • – Reactors: Design and Data Analysis • – Bioseparations • – Application and Industrial considerations Oxygen transfer rate Oxygen utilization rate Cleaning in place/sterilization in place