A. FUNDAMENTALS OF BIOPROCESS TECHNOLOGY
1. Bioprocess Technology
Bioprocess technology applies microorganisms, cells, enzymes, and other biological systems to produce or transform useful products under controlled conditions. It has applications in food, pharmaceuticals, biotechnology, agriculture, chemicals, and environmental processing.
2. Fermentation
Fermentation is a biological process in which microorganisms or cells convert substrates into metabolic products under controlled conditions. In industrial biotechnology, the term also broadly refers to controlled cultivation of microorganisms or cells, including processes that are not strictly fermentative in the biochemical sense.
3. Industrial Bioprocess Products
Bioprocesses are used to manufacture products such as enzymes, organic acids, amino acids, antibiotics, vitamins, microbial biomass, bioactive compounds, solvents, polysaccharides, and biofuels.
4. Fermented Foods and Beverages
Examples of foods and beverages produced through microbial fermentation include yogurt, cheese, bread, beer, wine, fermented vegetables, soy-fermented products, and other traditional fermented foods.
5. Lactic Acid Bacteria
Lactic acid bacteria, including genera such as Lactobacillus, Lactococcus, Leuconostoc, Pediococcus, and Streptococcus, are important in the manufacture of fermented dairy products and other fermented foods. Taxonomic changes have resulted in several former Lactobacillus species being reassigned to new genera.
B. SINGLE-CELL PROTEIN AND MICROBIAL BIOMASS
6. Single-Cell Protein
Single-cell protein (SCP) refers to microbial biomass produced for use as a protein-rich food or feed ingredient. The term encompasses biomass from microorganisms rather than referring literally to individual cells.
7. Microorganisms Used for SCP Production
Microbial biomass suitable for SCP production may be obtained from yeasts, bacteria, filamentous fungi, and microalgae. Selection depends on nutritional composition, safety, growth rate, substrate, and intended application.
8. Yeasts for Microbial Biomass
Yeasts that have been investigated or used for microbial biomass production include species from Candida, Debaryomyces, Kluyveromyces, and related genera. Strain selection depends on substrate utilization, yield, safety, and regulatory acceptance.
9. Microalgae for Biomass Production
Microalgae such as Chlorella and Arthrospira are cultivated as protein-rich biomass. Arthrospira is commonly marketed as “spirulina,” although it is a cyanobacterium rather than a true eukaryotic alga.
10. Bacterial Biomass
Bacterial genera investigated for biomass production include Methylococcus, Methylomonas, Methylobacterium, Cellulomonas, and other suitable organisms. The choice depends on substrate, growth conditions, safety, and final application.
11. Filamentous Fungi
Filamentous fungi can be used for production of microbial biomass and food ingredients. Examples include selected species of Aspergillus, Trichoderma, and other food-safe fungi. Not every species within these genera is suitable for food use because some strains can produce undesirable metabolites or toxins.
C. YEAST AND MICROBIAL ENZYME PRODUCTION
12. Baker’s Yeast Production
Commercial baker’s yeast is primarily produced using Saccharomyces cerevisiae under highly aerobic cultivation conditions. Industrial production commonly uses controlled, fed-batch cultivation to maximize biomass formation while limiting excessive ethanol production.
13. Substrates for Yeast Biomass Production
Yeast biomass can be produced using substrates such as molasses, hydrolyzed sugars, starch-derived substrates, whey-derived sugars, and other suitable carbohydrate sources. The substrate must meet the nutritional and regulatory requirements of the production strain.
14. Brewing Yeasts
Brewing commonly uses Saccharomyces cerevisiae strains for ales and Saccharomyces pastorianus for traditional lager production. Yeast selection affects alcohol production, flavour compounds, attenuation, and fermentation performance.
15. Microbial Enzymes
Microorganisms are important commercial sources of enzymes such as amylases, proteases, lipases, lactases, pectinases, cellulases, and invertases. Enzymes may be produced extracellularly or intracellularly depending on the microorganism and process.
16. Invertase and Lactase
Microbial enzymes such as invertase and β-galactosidase (lactase) can be produced commercially using suitable microorganisms. β-galactosidase hydrolyzes lactose into glucose and galactose, while invertase hydrolyzes sucrose into glucose and fructose.
D. AMINO ACIDS AND ANTIBIOTICS
17. Corynebacterium glutamicum
Corynebacterium glutamicum is an important industrial microorganism used for the production of L-glutamic acid and L-lysine. Metabolic engineering and strain improvement have substantially increased its industrial productivity.
18. Microbial Antibiotics
Microorganisms have been used to produce numerous antibiotics, including penicillins, cephalosporins, streptomycin, erythromycin, and other antimicrobial compounds. Industrial production generally uses highly selected strains and controlled fermentation processes.
19. Penicillin-Producing Organisms
Industrial penicillin production is historically associated with Penicillium chrysogenum, now commonly classified as Penicillium rubens. The organism was developed through extensive strain improvement for high penicillin productivity.
20. Discovery of Penicillin
Alexander Fleming observed the antibacterial activity of a substance produced by a Penicillium mold in 1928. The subsequent development of penicillin into a practical therapeutic antibiotic involved major contributions from Howard Florey, Ernst Boris Chain, and their collaborators.
21. Nobel Prize and Penicillin
Alexander Fleming, Ernst Boris Chain, and Howard Florey were awarded the 1945 Nobel Prize in Physiology or Medicine for the discovery of penicillin and its curative effect in infectious diseases.
E. DOWNSTREAM PROCESSING
22. Downstream Processing
Downstream processing includes the operations used to recover, concentrate, purify, formulate, and stabilize a biological product after its production stage. It may include cell removal, filtration, centrifugation, extraction, precipitation, chromatography, concentration, drying, and formulation.
23. Nucleotides and Nucleosides
Microbial processes can produce nucleotides and nucleosides for food, pharmaceutical, nutritional, and industrial applications. Production may involve fermentation followed by recovery and purification.
24. Microbial Organic Acids
Important organic acids produced through microbial processes include citric acid, lactic acid, gluconic acid, acetic acid, and itaconic acid. The microorganism and production process depend on the target product.
25. Citric Acid Production
Citric acid is commercially produced mainly by microbial fermentation, particularly using selected strains of Aspergillus niger. Both submerged and surface fermentation technologies have been used, although modern industrial production commonly uses submerged fermentation.
26. Aspergillus niger
Aspergillus niger is an important industrial microorganism used for production of citric acid and several enzymes. Industrial strains are selected and controlled to meet product-quality and safety requirements.
F. MICROBIAL POLYSACCHARIDES AND PIGMENTS
27. Microbial Polysaccharides
Microorganisms produce commercially important extracellular polysaccharides such as xanthan gum, dextran, pullulan, gellan, and other biopolymers. These materials can function as thickeners, stabilizers, film-forming agents, or specialty ingredients.
28. Pullulan
Pullulan is a microbial extracellular polysaccharide produced mainly by Aureobasidium pullulans. It has film-forming and oxygen-barrier properties and has applications in food, pharmaceutical, and packaging technologies.
29. Xanthan Gum
Xanthan gum is an extracellular polysaccharide produced industrially by selected strains of Xanthomonas. It is widely used as a thickener, stabilizer, and rheology modifier in food and other industries.
30. Dextran
Dextrans are microbial α-glucans produced by certain lactic acid bacteria, particularly selected strains of Leuconostoc and related organisms. Their structure and properties depend on the producing microorganism and fermentation conditions.
31. Microbial Pigments
Microorganisms can produce pigments including carotenoids and other natural colour compounds. Microbial pigment production is investigated for food, feed, pharmaceutical, cosmetic, and biotechnology applications, subject to safety and regulatory requirements.
G. ALCOHOLIC FERMENTATION AND BEVERAGE TECHNOLOGY
32. Hops in Beer
Hops (Humulus lupulus) contribute characteristic bitterness, aroma, and flavour to beer. Hop compounds also contribute to beer stability and influence sensory properties.
33. Distilled Alcoholic Beverages
Vodka, whisky, rum, and tequila are examples of distilled alcoholic beverages. Their production generally involves fermentation followed by distillation, although raw materials and processing methods differ substantially among products.
34. Mold-Fermented Foods
Selected filamentous fungi are used in the manufacture of traditional fermented foods such as soy sauce, miso, tempeh, and certain fermented soybean products. The microorganisms and processing methods vary according to the product and geographical tradition.
35. Industrial Ethanol Production
Industrial ethanol can be produced by microbial fermentation of carbohydrate-rich substrates such as sugar solutions, molasses, and hydrolyzed starch materials. The choice of substrate depends on availability, economics, process technology, and intended use.
36. Antifoaming Agents
Foam can develop during microbial cultivation because of proteins, polysaccharides, cells, and gas aeration. Food-grade or process-approved antifoaming agents may be used to control excessive foam. The selection must be compatible with the microorganism, process, downstream operations, and regulatory requirements.
37. Distillation of Ethanol
Fermentation broths contain ethanol together with water and numerous other compounds. Distillation is commonly used to concentrate ethanol, while additional purification technologies may be required depending on the desired product specification.
H. BIOPROCESS ENGINEERING
38. Fermenter or Bioreactor Design
A fermenter or bioreactor provides controlled conditions for biological production. Important design features include mixing, aeration, temperature control, pH control, sterilization, agitation, pressure control, feeding systems, instrumentation, and foam management.
39. Process Yield and Bioreactor Conditions
Product yield and productivity are influenced by microbial strain, substrate concentration, pH, temperature, dissolved oxygen, agitation, aeration, nutrient availability, feeding strategy, and product inhibition. Bioreactor design must therefore match the biological characteristics of the production system.
40. Scale-Up
Scale-up is the process of transferring a biological production process from laboratory or pilot scale to a larger production scale while maintaining appropriate performance. Important scale-up parameters include oxygen transfer, mixing, heat transfer, power input, shear, mass transfer, and process control.
41. Computer Applications in Bioprocessing
Computer systems are widely used for data acquisition, process monitoring, data logging, modelling, automation, statistical analysis, and process control. Modern bioprocess facilities increasingly use sensors and digital control systems for real-time monitoring.
42. Solid-Liquid Separation
Recovery of biological products may require separation of cells or solids from fermentation broth. Common operations include centrifugation, filtration, sedimentation, coagulation, and flocculation, depending on the characteristics of the broth and product.
43. Primary Product Recovery
Primary recovery may include cell removal, cell disruption where necessary, liquid-liquid extraction, adsorption, precipitation, membrane separation, or other separation techniques. The selected method depends on whether the product is intracellular or extracellular and on its physical and chemical properties.
44. Product Purification
High-value biological products may require purification by methods such as chromatography, membrane separation, crystallization, selective precipitation, extraction, and other fractionation techniques. The purification strategy is selected according to product purity requirements and process economics.
45. Product Drying and Formulation
Drying and formulation can improve product stability and facilitate storage, transport, and use. Technologies may include spray drying, freeze drying, vacuum drying, and other validated drying methods, depending on product sensitivity.
I. IMMOBILIZATION, ENCAPSULATION AND ENVIRONMENTAL BIOPROCESSING
46. Immobilized Cells
Microbial or enzyme immobilization involves restricting biological catalysts within a defined region while retaining their catalytic activity. Methods include adsorption or binding to carriers, covalent attachment, cross-linking, and entrapment.
47. Microencapsulation
Microencapsulation surrounds cells, enzymes, or other biological materials within a protective coating or matrix. It can improve handling and stability and may provide controlled release or protection against environmental stresses. Its suitability depends on the specific biological material and application.
48. Waste Treatment
Microorganisms are widely used in biological wastewater and waste treatment. Microbial processes can convert or remove organic matter, nitrogen compounds, phosphorus, and selected contaminants through aerobic, anaerobic, and other biological pathways.
49. Biofuels
Bioprocess technologies are used to produce biofuels such as bioethanol, biobutanol, biogas, biodiesel from biological feedstocks, and other renewable fuels. The process depends on the feedstock, microorganism or catalyst, conversion pathway, and desired fuel.
50. Strain Improvement
Industrial microorganisms are improved to increase product yield, productivity, substrate utilization, tolerance to process stresses, product specificity, and genetic stability. Strain improvement may involve classical selection and mutagenesis, adaptive evolution, metabolic engineering, recombinant DNA methods, and modern genome-editing technologies where appropriate.
BIOPROCESS TECHNOLOGY: KEY CONCEPT
Bioprocess technology integrates microbiology, biochemistry, molecular biology, chemical engineering, process engineering, and downstream processing to convert biological raw materials into useful products. A complete industrial bioprocess generally includes strain selection and improvement, inoculum development, medium preparation, sterilization, bioreactor operation, process monitoring and control, product recovery, purification, formulation, and quality assurance.
The successful design of a bioprocess depends on maintaining suitable biological and engineering conditions while achieving the required yield, productivity, product quality, safety, reproducibility, and economic performance.