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Objective. Bioprocess/fermentation technology. Examples of microbial products
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Objective
Ø To study general aspects of bioprocesses, considering:
- Principles of microbial growth
- Fermentation control and monitoring
- Characteristics of large-scale fermentation
- Isolation and purification
- Fermentation scale up
Ø To describe the general characteristics of enzymes
Bioprocess/fermentation technology
Bioprocess or fermentation technology is an important component of most “old” and “new” biotechnology processes and will normally involve complete living cells (microbe, mammalian or plant), organelles or enzymes as the biocatalyst, and will aim to bring about specifi c chemical and/or physical changes in biochemical materials derived from the medium. To be viable in any specifi c industrial context, bioprocessing must possess advantages over competing methods of production such as chemical technology. In practice, many bioprocessing techniques will be used industrially because they are the only practical way in which a specifi c product can be made (e. g. vaccines, antibiotics). Biochemical engineering covers the design of vessels and apparatus suitable for performing such biochemical reactions or transformations. Later these vessels will be analyzed.
Bioprocess technology, were derived in part from the use of MO to produce foods such as cheeses, yoghurts, beverages such as beers, wines and so on. Then, we can relate Biotechnology with Industrial Microbiology as very important area that contribute to develop Biotechnology.
Now let’s see some features of an industrial MO:
ü It must be able to produce the substance of interest
ü Capable of growth and product formation in large scale cultivation
ü To grow rapidly and produce the desired product in a short period of time
ü Able to grow in an inexpensive liquid culture media
ü It should not be pathogenic
ü Susceptible to genetic manipulation
An industrial MO should not be pathogenic especially to human or economically important animals or plants. Because of the high cell densities in the industrial bioreactor and the virtual impossibility of avoiding contamination of the environmental outside the bioreactor, a pathogen would present potentially disastrous problems.
A genetically stable and easily manipulable MO is thus a clear advantage. We will obtain better results, because we can enhance some characteristics for producing more quantities of final product.
Bioprocessing in its many forms involves a multitude of complex enzyme-catalyzed reactions within specifi c cellular systems, and these reactions are critically dependent on the physical and chemical conditions that exist in their immediate environment. Successful bioprocessing will only occur when all the essential factors are brought together.
Examples of microbial products
Many products can be obtained from bioprocesses. Between the most important products, we can mention the following:
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ü Enzymes
Every organism produces a large variety of enzymes. Extracellular enzymes are capable of digesting insoluble polymers such as cellulose, proteins and starch. The products of digestion are then transported into the cell where they are used as nutrient for growth. Various enzymes are used in the food and health industries.
ü Antibiotics
Of manufactured microbial products, the most important for the health industry are antibiotics. They are agents for treatments of infectious disease and are produced by MO to kill or inhibit the growth of another MO. They are typically secondary metabolites. They can be produced by filamentous fungi and by some bacteria.
ü Vitamins and amino acids
They are growth factors that are often used pharmaceutically or are added to food. Several important vitamins and amino acids are produced by biocatalytic processes.
ü Alcohol and alcoholic beverages
Most fruits juices and grains will undergo a natural fermentation catalyzed by wild yeast present on these materials. From these natural fermentations, strains of yeast have been selected for more controlled production.
The most important alcoholic beverages are wine, produced by fermentation of fruit juices, beer or ale, produced by the fermentation of malted grain and distilled beverages, produced from concentrating alcohol from fermentation by distillation.
The product formation stages in bioprocess technology are essentially very similar no matter what organism is selected, what medium is used or what product formed. In all examples, large numbers of cells are grown under defi ned controlled conditions. The organisms must be cultivated and motivated to form the desired products by means of a physical/technical containment system (the bioreactor), and the correct medium composition and environmental growth-regulating parameters such as temperature and aeration. Optimization of the bioprocess spans both the bio- and the technical systems.
Large numbers of cells are invariably involved in these processes and the bioreactor ensures their close involvement with the correct medium and conditions for growth and product formation.
Here, we describe microbial growth and product formation in an industrial context and will see that some products are formed during exponential growth, while others are produced only after exponential growth has finished.
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