Podcast
Questions and Answers
Which material is NOT typically used in modern microbial filters?
Which material is NOT typically used in modern microbial filters?
What is a major advantage of using filtration for preparing heat-sensitive liquids?
What is a major advantage of using filtration for preparing heat-sensitive liquids?
Which of the following is NOT a quality to consider when choosing antimicrobial chemical agents?
Which of the following is NOT a quality to consider when choosing antimicrobial chemical agents?
In a fermentation process, which of the following components is crucial for the production of metabolic products?
In a fermentation process, which of the following components is crucial for the production of metabolic products?
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What is a common illness associated with fermentation?
What is a common illness associated with fermentation?
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Which gas is commonly used for sterilizing plastics such as petri dishes?
Which gas is commonly used for sterilizing plastics such as petri dishes?
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What can result from unsterile air in aerobic fermentations?
What can result from unsterile air in aerobic fermentations?
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When performing continuous fermentation, what is a primary concern with contaminants?
When performing continuous fermentation, what is a primary concern with contaminants?
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What is a primary advantage of enzyme immobilization?
What is a primary advantage of enzyme immobilization?
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Which of the following is NOT a characteristic of an ideal carrier for enzyme immobilization?
Which of the following is NOT a characteristic of an ideal carrier for enzyme immobilization?
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Which technique involves the use of microscopic hollow spheres for enzyme immobilization?
Which technique involves the use of microscopic hollow spheres for enzyme immobilization?
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What physical force is involved in the adsorption method of enzyme immobilization?
What physical force is involved in the adsorption method of enzyme immobilization?
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Which of the following is a disadvantage of the entrapment technique?
Which of the following is a disadvantage of the entrapment technique?
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Which of the following is a commonly used functional group for covalent binding in enzyme immobilization?
Which of the following is a commonly used functional group for covalent binding in enzyme immobilization?
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Why might adsorption be favored over other methods of enzyme immobilization?
Why might adsorption be favored over other methods of enzyme immobilization?
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Which of the following statement about synthetic support materials is true?
Which of the following statement about synthetic support materials is true?
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What is a common method for sterilizing materials before they are added to the fermenter?
What is a common method for sterilizing materials before they are added to the fermenter?
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What is the primary purpose of maintaining aseptic conditions during fermentation?
What is the primary purpose of maintaining aseptic conditions during fermentation?
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What is one benefit of using lactic acid as a contamination inhibitor in large-scale processes?
What is one benefit of using lactic acid as a contamination inhibitor in large-scale processes?
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What device is typically used to sterilize air in process industries?
What device is typically used to sterilize air in process industries?
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What is a recommended condition for steam sterilization of fermenters?
What is a recommended condition for steam sterilization of fermenters?
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Which method is NOT effective for air sterilization?
Which method is NOT effective for air sterilization?
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What is a common characteristic of synthetic media compared to crude media during sterilization?
What is a common characteristic of synthetic media compared to crude media during sterilization?
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Study Notes
Enzyme Inhibition
- Enzyme inhibition is a process where a molecule (inhibitor) binds to an enzyme and reduces its activity.
- This prevents the enzyme from interacting with its substrate and, therefore, prevents the substrate from being converted into a product.
Types of Inhibition
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Competitive Inhibition: The inhibitor binds to the active site, preventing the substrate from binding.
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Uncompetitive Inhibition: The inhibitor binds only to the enzyme-substrate complex, preventing it from converting the substrate to a product.
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Noncompetitive Inhibition: The inhibitor can bind to either the enzyme or the enzyme-substrate complex, but not the active site. This reduces the overall enzyme activity.
Rate Equations
- The rate equations describe how the rate of a reaction affected by factors such as enzyme concentration, substrate concentration, and the presence of an inhibitor.
Enzyme Immobilization
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Enzyme immobilization is the process of attaching enzymes to an insoluble support medium or encapsulating them.
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This restricts the enzyme's movement.
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Advantages:
- Reusable enzymes
- Facilitates continuous operations.
- Easier enzyme/product recovery
- More stable enzymes
- Facilitates process control of product yield and quality
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Methods:
- Adsorption: Enzymes are physically attached to a support.
- Entrapment: Enzymes are enclosed in a porous matrix.
- Cross-linking: Enzymes are covalently bonded to another molecule to form a more stable complex.
- Covalent binding: Enzymes are directly attached to a support material through covalent bonds.
Ideal Carrier/Support Specifications
- Inert
- Cheap
- Physically strong and stable
- Reduces product inhibition
- Discourages microbial growth
- Discourages non-specific adsorption
Entrapment Technique
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Common support material: polyacrylamide, calcium alginate, gelatin.
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Suitable for low molecular weight substrates and products.
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Advantages:
- Enzymes are not chemically modified.
- Enzyme properties are not altered.
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Disadvantages:
- Deactivation of the enzyme may occur during gel formation.
- Enzyme leakage may occur based on the support material's pore size. -Diffusional limitations may occur, reducing the accessibility of the substrate.
Microencapsulation
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Enzymes are entrapped in semi-permeable/microscopical membranes.
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Not suitable for proteolytic enzymes or macro-molecular substrates.
Cross-linking
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Covalent bonds are formed between enzyme molecules using multifunctional reagents, creating a 3-dimensional structure.
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Used to stabilize adsorbed enzymes and prevent leakage from materials like polyacrylamide gels
Covalent Binding
- The enzyme is bonded to the surface through covalent bond formation using specific functional groups.
Most Commonly Used Functional Groupings
- Amino groups
- Carboxyl groups
- Hydroxyl groups
- Sulphydryl groups
Advantages (Covalent Binding)
- Very strong bonding (less enzyme leakage)
- Small amounts of enzymes are immobilized
- Provides more permanent linkage between the enzyme and support material
Water-Insoluble Support Materials
- Synthetic: acrylamide-based polymers, maleic anhydride polymers, styrene-based polymers
- Natural: agarose, cellulose, dextran, glass, starch
Adsorption
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Oldest method; involves the physical attachment of enzymes to a surface via weak physical forces (van der Waals forces, dispersion forces)
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Advantages:
- Easy and simple immobilization procedure.
- Reversible adsorption process.
- Enzymes are not deactivated. -Separation and purification of the enzymes possible during immobilization.
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Disadvantages:
- Many other substances can be attached alongside immobilized enzymes due to the nonspecific nature of adsorption.
- Loading of enzyme into limited amounts of surface area is low.
- Weak bonding strength.
Materials for Adsorption
- Silica gel
- Metal oxides
- Glass
- Organic polymers
- Porous carbon
- Clay
Microbial Control
- Sterilization: Removal/destruction of all microbes (including endospores).
- Aseptic: Environment/procedure free of pathogens.
- Disinfection: Use of physical/chemical agents (disinfectants) to treat inanimate objects.
- Antisepsis: Using chemical/antimicrobial agents on skin/tissues.
- Degerming: Removal of microbes from a surface using rubbing.
- Sanitizing: Disinfecting places/utensils used by public to reduce pathogenic microbes and meet public health standards.
- Pasteurization: Use of heat to kill pathogens and reduce spoilage microorganisms in food/beverages.
Microbial Death
- Permanent termination of an organism's vital processes.
- Factors affecting death rate:
- Number of microorganisms
- Nature of microorganisms.
- Temperature & pH of the environment.
- Concentration of the agent
- Mode of action of the agent
- Presence of solvents/interfering organic matter/inhibitors
- Cellular targets of physical/chemical agents: cell wall, cell membrane, cellular synthetic processes (DNA/RNA), proteins.
Methods of Physical Control
- Heat
- Radiation
- Filtration
- Ultrasonic waves
- Cold
Heat
- Moist heat: Hot water, boiling water, steam (vaporized water); 60–135°C
- Dry heat: Heated by flame or electric coil; 160°C+
Radiation
- Types: Ionizing (x-rays, gamma rays) - creates free radicals destroying microbial proteins and DNA -Ultraviolet (UV) - damages nucleic acids by binding adjacent thymine bases; microbe dies
Filtration
- Modern microbial filters use cellulose acetate, polycarbonate, plastic materials (teflon & nylon); pores vary from coarse (8 microns) to ultrafine (0.02 microns)
Chemical Agents
- Gases for sterilization: ethylene oxide (ETO), beta propiolactone (BPL), formaldehyde
- Qualities in choosing antimicrobial chemical agents:
- Rapid action in low concentration
- Solubility in water/alcohol and long-term stability
- Broad-spectrum microbicidal action without being toxic to human/animal tissues
- Penetrates inanimate surfaces for cumulative/persistent action
- Resistance to inactivation by organic matter
- Non-corrosive/non-staining properties
- Sanitizing and deodorizing properties
- Affordability & ready availability
Fermentation
- Biochemical process using microorganisms on a substrate in the presence of nutrients to produce metabolic products.
- Factors for Success: Microorganism, medium, fermenter, nutrients/additives, continuous vs batch process.
- Issues/Challenges: Contamination, contaminated product outweighing desired product (especially in continuous fermentation), interfering with product recovery, unstable air presence resulting in spoilage.
- Solutions: Sterilize medium/inoculum/fermenter/pipes/valves/materials/air, aseptic conditions, maintain desired pH, use appropriate filters.
Sterilization of Medium, Air and Fermenters
- Methods: Boiling in water, passing steam, autoclaving (pressurized steam).
- Scale Processes: Adjusting pH, using contamination inhibitors (like lactic acid).
- Sensitive Enzymes/Nutrients: Separate initially, sterilize separately using bacterial filtration, add back to medium.
- Air Sterilization: Heating, UV rays, germicidal sprays, filtration (smaller/bigger pores)
- Fermenter Sterilization: Steam (15 PSIG) for 20 minutes, followed by flushing with sterile air.
Biochemical Engineering
- Applied chemical engineering principles using biological catalysts to desired chemical transformation, conducting biological processes on an industrial scale.
- Role: Biochemical engineers work with biological scientists to design reactors/processes, using the most suitable biological catalyst under optimal environmental condition for desired chemical transformations and optimal separation of the product from the mixture in the most economic way.
Biological Processes
- Main advantages: Mild reaction condition, specificity, effectiveness, renewable resources, recombinant DNA technology.
- Main disadvantages: Complex product mixtures, dilute aqueous environments, contamination, variability.
What Does Life Really Look Like?
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It discusses the history of microbiology.
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It mentiones the father of microbiology, Antonie van Leeuwenhoek.
Classification of Living Organisms
- Kingdom Monera (bacteria)
- Kingdom Protista (protozoa, algae)
- Kingdom Fungi (yeast, mushrooms)
- Kingdom Plantae (plants)
- Kingdom Animalia (animals)
Biological Basics
- Cells are the basic units of life.
- Prokaryotes: Simple cells (no nucleus or membrane-bound organelles).
- Eukaryotes: Complex cells (having a nucleus and membrane-bound organelles).
- Chemical composition: Water, trace elements, proteins, nucleic acids, lipids.
- Microbial Diversity: Psychrophile, Mesophile, Thermophile; Aerobic, Anaerobic, Facultative.
Derivation of Michaelis-Menten Model
- The model derives the rate of product formation and substrate consumption based on the enzyme-substrate complex assuming the product-releasing step to be the slower reaction rate and negligible change in the intermediate concentration.
- It emphasizes deriving the rate equation using the Michaelis-Menten and Briggs-Haldene approaches showing how the latter simplifies to the former if the product releasing step reaction rate is much slower than the enzyme-substrate dissociation step.
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