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Large scale microbial fermentation and its problem numair ahmad
This document discusses the principles and techniques of large-scale microbial fermentation, highlighting the distinction between surface and submersion techniques used for producing microbial products. It details key microbial products and their corresponding organisms, outlines the fermentation process including the use of fermenters, and emphasizes the significance of the fermentation medium. Additionally, it addresses various contamination issues faced in microbial fermentation, including bacterial, viral, fungal, and dairy contamination, and their potential impacts on production yields.
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Large scale microbial fermentation and its problem numair ahmad
- 1. 1 Large scale microbialfermentation principle and its problems Numair Ahmad 24 Indus International Institute
- 2. 2 What is fermentation? •Pasteur’s definition: “life without air”, anaerobe red ox reactions in organisms • New definition: a form of metabolism in which the end products could be further oxidized For example: a yeast cell obtains 2 molecules of ATP per molecule of glucose when it ferments it to ethanol
- 3. 3 What is fermentationtechniques (1)? Techniques for large-scale production of microbial products. It must both provide an optimum environment for the microbial synthesis of the desired product and be economically feasible on a large scale. They can be divided into surface (emersion) and submersion techniques. The latter may be run in batch, fed batch, continuous reactors In the surface techniques, the microorganisms are cultivated on the surface of a liquid or solid substrate. These techniques are very complicated and rarely used in industry
- 4. 4 What is fermentationtechniques (2)? In the submersion processes, the microorganisms grow in a liquid medium. Except in traditional beer and wine fermentation, the medium is held in fermenters and stirred to obtain a homogeneous distribution of cells and medium. Most processes are aerobic, and for these the medium must be vigorously aerated. All important industrial processes (production of biomass and protein, antibiotics, enzymes and sewage treatment) are carried out by submersion processes.
- 5. 5 Some important fermentationproducts Product Organism Use Ethanol Saccharomyces cerevisiae Industrial solvents, beverages Glycerol Saccharomyces cerevisiae Production of explosives Lactic acid Lactobacillus bulgaricus Food and pharmaceutical Acetone and butanol Clostridium acetobutylicum Solvents α-amylase Bacillus subtilis Starch hydrolysis
- 6. 6 Some important fermentationproducts
- 7. 7 Some important fermentationproducts
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- 9. 9 General Aspects ofFermentation Processes
- 10. 10 Fermenter and itstypes The heart of the fermentation process is the fermenter. Simple fermenters (batch and continuous) Fed batch fermenter Air-lift or bubble fermenter Cyclone column fermenter Tower fermenter Other more advanced systems, etc The size is few liters (laboratory use) - >500 m3 (industrial applications)
- 11. 11 Cross section ofa fermenter for Penicillin production
- 12. 12 In the manufactureof penicillin, fermentation is the preferred route. The fermentation substrate consists mainly of the sucrose found in corn steep liquor and lactose together with minerals and phenylacetic acid. The preferred mold is Penicillium chrysogenum and the first stage of the process is the transfer of the mold to the fermenter from the test tube where it has been stored.
- 13. 13 The whole processis aerobic (it requires air). The fermentation is carried out over 4 or 5 days at 25- 27°C. This gives a yield of about 0.5% penicillin. The mycelium, the mold cells plus insoluble metabolites, is filtered off in a coated drum filter.
- 14. 14 The filtrate isadjusted the pH 2 with sulphuric acid. At this pH, the penicillin exists as an undissociated acid; consequently, it is soluble in organic solvents. After extraction the solution is decolourised and impurities are removed by activated carbon in a second drum filter.
- 15. 15 The penicillin isthen precipitated by addition of a solution of potassium acetate. This converts the penicillin into a negative ion, which makes it insoluble in the organic solvent. Inn the final steps the penicillin is crystallized and dried.
- 16. 16 Flow sheet ofa multipurpose fermenter and its auxiliary equipment
- 17. 17 Fermentation medium • Definemedium nutritional, hormonal, and substratum requirement of cells • In most cases, the medium is independent of the bioreactor design and process parameters • The type: complex and synthetic medium (mineral medium) • Even small modifications in the medium could change cell line stability, product quality, yield, operational parameters, and downstream processing.
- 18. 18 Medium composition Fermentation mediumconsists of: • Macronutrients (C, H, N, S, P, Mg sources water, sugars, lipid, amino acids, salt minerals) • Micronutrients (trace elements/ metals, vitamins) • Additional factors: growth factors, attachment proteins, transport proteins, etc) For aerobic culture, oxygen is sparged
- 19. 19 Inoculums Incoculum is thesubstance/ cell culture that is introduced to the medium. The cell then grow in the medium, conducting metabolisms. Inoculum is prepared for the inoculation before the fermentation starts. It needs to be optimized for better performance: • Adaptation in the medium • Mutation (DNA recombinant, radiation, chemical addition)
- 20. Problems faced in microbialfermentation 20
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- 22. 22 This is themost common type of contaminant in bacterial cultures. Depending on the type of bacterium contaminating the process, the effects brought about are different. In all cases, one may expect reduced yield of product, and possible contamination by metabolites of contaminating bacteria. In some cases toxins may be produced by contaminants.
- 23. 23 The probability ofoccurrence of a particular type of contaminations caused by bacteria may differ, depending on the process itself and the organism used in the process. One of the most frequently occurring contaminants are lactic acid bacteria and sporulating bacteria. Clean-up and re-occurrence prevention of especially the latter presents a considerable challenge.
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- 25. 25 Viruses are themost dangerous contaminant in this type of fermentation. Due to small sizes, they are the toughest enemy to prevent entering the process, and their occurrence may result in very long, lasting even several months, paralysis of whole facility productivity. Due to the fact that eukaryotic cell cultures are usually used for production of highly valuable products, a risk of running fermentation without optimal protection is something what can cost you a lot.
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- 27. 27 Fungal cultures canbe contaminated also by other fungi. As this type of contamination may be relatively hard to detect, good measures of precaution should be undertaken to prevent it.
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- 29. 29 In dairy industry,controlling contamination issues is very important, not only due to possible health hazards. Milk is a raw material, which cannot always be sterilized, and almost every batch contains bacteriophages infectious to bacteria used in production process.
- 30. 30 Moreover, some phagesattacking lactic acid bacteria are resistant to pasteurization, and thus, they are much harder to eliminate. As it is not always possible to prevent bacteriophages from entering production process, there is a possibility to prevent re-infections, which are the ones to blame for vast majority of production failures.