30 Questions
What are some parameters that are measured and controlled during fermentation?
Temperature, O2 concentration, pH, cell mass, product concentration
What is the purpose of the inoculum build-up stage in fermentation?
To produce sufficient biomass to inoculate the production stage fermenter.
What are the different stages involved in the course of fermentation?
Inoculum build-up, Preculture fermentations, Production fermenter
What are the different scales of production of microbial biomass or metabolites?
Laboratory flask/bench scale, Laboratory fermentor/preparative scale, Pilot plant stage, Commercial fermentor
Why is the determination of culture conditions important in fermentation?
To find the optimum values for nutritional requirements, temperature, pH, and oxygen supply.
What is the significance of monitoring O2 dynamics in fermentation?
To understand how volume increases affect O2 demand in the fermentation process.
What is a batch system in the context of bacterial culture systems?
A closed bacterial culture system with specific nutrient, temperature, pressure, aeration, and other environmental conditions to optimize growth.
Why can batch cultures only complete a limited number of life cycles?
Because nutrients are not added, nor waste products removed during incubation, leading to nutrient consumption and growth cessation.
What is a fed-batch system in bioreactors?
One or more nutrients are fed to the bioreactor during cultivation, and the product(s) remain until the end of the run.
How does a fed-batch culture differ from a batch culture?
In a fed-batch culture, nutrients are supplied during cultivation to prevent nutrient depletion, unlike in batch cultures where nutrients are not added during incubation.
What is the main advantage of using a fed-batch system over a conventional batch culture?
The ability to control the concentration of fed substrate in the culture liquid at desired levels, often at low levels.
Give an example of a situation where fed-batch culture is particularly effective.
When controlling concentrations of a nutrient or nutrients significantly impacts the yield or productivity of the desired metabolite.
What are the essential nutrients required for microbial growth?
Mineral elements, vitamins, oxygen
What is the main factor in obtaining the criteria for microbial biomass production?
Culture medium
What are examples of carbon sources for biomass and energy in heterotrophic microorganisms?
Organic materials like sugar, starch, organic acids, proteins, peptides, amino acids
What are some challenges that may arise when transitioning from a lab scale to a pilot plant in fermentor design?
Low gas transfer pattern, media with high viscosity
What is an example of a by-product used as a carbon source for microbial growth?
Whey
What are the constituents of a medium in fermentor design required to satisfy?
Requirement for cell biomass & metabolite, adequate supply energy for biosynthesis & cell maintenance
What is the purpose of media formulation equation stoichiometry in fermentor design?
Economical design of media, minimize waste, knowledge of elemental composition
What are the criteria for raw material selection in microbiological media?
Cost, availability, uniform solubility, rheology, foaming property, material handling, smell, gas, storage, government regulation
What are the constituents required by all microorganisms for growth in microbiological media?
Source of energy, carbon, nitrogen, mineral elements, vitamins, oxygen
Why is the carbon source important in media formulation in fermentor design?
For biosynthesis & energy generation, makes up 50% of dry weight of cell
What is the theoretical yield used for in media formulation in fermentor design?
Estimating the quantity of cell dry matter produced and substrate utilized
What does the yield coefficient (Y) help estimate in fermentor design?
Requirement for biosynthesis & energy generation
What is the purpose of a continuous system in fermentation?
Maintain exponential growth rate for a prolonged period
How can population density and growth rate be controlled in a bioreactor?
By adjusting the concentration of limiting nutrient and the dilution rate (flow rate)
What is the function of a bioreactor?
To support a biologically active environment for chemical processes involving organisms or biochemically active substances
Explain the concept of substrate inhibition.
Substrate inhibition occurs when high substrate concentrations inhibit enzyme activity
What is catabolite repression in the context of fermentation?
Catabolite repression is the inhibition of certain metabolic pathways by preferred carbon sources
Describe the significance of extending the operation time in a fermenter.
It allows for continuous production of metabolites without interruptions
Study Notes
- Orbital shakers are now more commonly used than reciprocating machines in bioreactors.
- There are three main types of bioreactor systems: batch, fed-batch, and continuous.
- In a batch system, the fermenter is filled with raw materials and the culture is incubated until fermentation is complete.
- Fed-batch systems involve the addition of nutrients during cultivation to prevent nutrient depletion and control the concentration of fed substrate.
- Fed-batch culture is effective for various bioprocesses, including substrate inhibition, high cell density, glucose effect, catabolite repression, auxotrophic mutants, gene expression control, and extension of operation time.
- Continuous systems maintain exponential growth of microbes in the fermenter by adding fresh media at regular intervals and extracting the metabolite or product continuously.
- Bioreactors are vessels used to carry out chemical processes involving organisms or biochemically active substances derived from organisms.
- Dialysis systems are used for extended exponential phase cultivation, concentrated biomass production, and easy recovery of macromolecules.
- The course of fermentation involves stages like inoculum build-up, prefermenter culture, production fermentations, and scale production of microbial biomass or metabolites.
- Culture conditions in bioreactors are determined based on optimum values of nutritional requirements, temperature, pH, and oxygen supply.
- The culture medium used in fermentation is an important factor in obtaining desired criteria, with considerations like cost, availability, solubility, rheology, foaming properties, and storage.
- Carbon sources are crucial for biomass and energy generation in microbial cultures, and different types of organic materials can be used as carbon sources.
- Media formulation in bioreactor design involves considering the stoichiometry of the constituents of the medium, such as carbon sources, energy sources, nitrogen sources, and other requirements for cell biomass and product formation.
Explore the process of batch system in fermentation, focusing on the closed bacterial culture system with specific environmental conditions and optimal growth. Understand the steps involving filling the fermenter with raw materials, inoculation, fermentation under ideal conditions, and product extraction.
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