Midterm Flashcards
Is it easier to harvest a product that is grown inside the cell or secreted from the cell? Why?
- secreted from the cell
- because it’s considered easier due to accessibility and simplicity, when a product is secreted, it is released into the surrounding medium making it readily accessible for harvesting without the need to disrupt the cell itself.
What is an example of an acellular product that can be made via fermentation?
Bioethanol generated from fermenting cells
Which of the following is a cellular product of fermentation?
A) kimchi
B) Heme
C) succinic acid
D) antibiotics
A - kimchi
Identify the types of prokaryotic and eukaryotic cells commonly involved in fermentation and industrial processes.
Prokaryotic : bacteria (lactobacillus)
Eukaryotic : fungi (yeast), algae, mammalian cells, insects
Why might we choose to use a mammalian cell for fermentation?
- various applications in antibody or vaccine production
Why might we choose insect cells?
- more ethical
- easy to work with
- cheaper
- useful for protein expression
Why might we choose bacterial cells?
- low cost
- high productivity
- rapid implementation
Ex. Lactobacillus
What conditions are needed for fermentation to occur?
- anaerobic (no O2 present)
- requires microorganisms like bacteria or yeast to obtain energy throughout
What is anabolism?
(Biosynthesis)
- uses cellular energy to synthesize biological products such as macromolecules
What is catabolism?
- the breakdown of complex compounds to provide energy and molecular intermediates
Is fermentation anabolic or catabolic?
Catabolic because fermentation is a series of reactions that involves the BREAKDOWN of organic molecules into energy.
What are the two common types of fermentation?
Alcohol fermentation and lactic acid fermentation
What is lactic acid fermentation?
- process used in mammalian cells and some types of microbes where pyruvate is converted to lactic acid which regenerates NAD+
What is alcoholic fermentation?
Mainly occurs in fungi (yeasts) resulting in the formation of ethanol from pyruvate which regenerates NAD+
What is upstream processing?
Design of reaction including cell selection, media preparation, cell growth, and scaling up
Explain the harvesting step of bioprocessing.
Collection of cells by centrifugation and may include cell lysis depending on the product
What is downstream processing?
Separation, purification, and processing of the final product which can vary significantly depending on the product
Choosing a feedstock is an example of:
A. Upstream processing
B. Fermentation
C. Harvesting
D. Downstream processing
A. Upstream processing
Optimizing a cell line is an example of:
A. Upstream processing
B. Fermentation
C. Harvesting
D. Downstream processing
A. Upstream processing
Crystallization is an example of:
A. Upstream processing
B. Fermentation
C. Harvesting
D. Downstream processing
D. Downstream processing
Malting and mashing in the brewing process is an example of:
A. Upstream processing
B. Fermentation
C. Harvesting
D. Downstream processing
A. Upstream processing
Describe 3 steps involved in upstream processes in wine production
- harvesting grapes
- pressing
- removal of skins for white wine
Describe 3 steps involved in upstream processing in beer production.
- substrate needed (barley, wheat, rice, corn)
- type of microorganisms (S. cerevisiae for ales or S. pastorianus for lagers)
- optimal conditions of fermenter depending on type of beer being made
Describe 3 steps involved in upstream processing in cheese production.
- milk pre-treatment: pasteurization which reduces microbial and enzymatic activity
- coagulation: formation of curd
- separation of solid curd from liquid whey which is accelerated by increasing temp., pH, reduction of LAB
Describe 3 steps involved in upstream processing in clean meat production.
- choosing animal species, and isolating a stable & immortalized population of cells
- optimize media
- Proliferation of cells in bioreactor
Describe 2 steps involved in downstream processing in beer production.
- beer settles with tannins, yeast, and proteins to become haze free
- cooled, aged, filtered for further clarification
- packaging into cans, bottles, or kegs
Describe 2 steps involved in downstream processing in wine production.
- aging in barrels (racking)
- final filtration
- bottling
Describe 2 steps involved in downstream processing in cheese production.
- draining and pressing
- ripening
- salting and aging
- packaging
Describe 2 steps involved in downstream processing in clean meat production.
- harvesting of the product
- processing steps to ensure flavour and texture (mechanical grinding, seasoning, shaping)
- packaging
When producing clean meats, what type of fermenter is used in the cell differentiation phase and why?
- cell proliferation bioreactors (stirred-tank)
- because they provide a controlled environment for cell growth and differentiation by regulating factors such as temp., pH, oxygen levels, and nutrient supply
What cell types are used for beer production?
- Yeast
- S. cerevisiae for ales
- S. pastorianus for lagers
What cell types are used for wine production?
- yeast
What cell types are used for cheese production?
Lactic acid bacteria (lactobacillus) and sometimes strains if mold (P. roqueforti or P. camemberti)
What cell types are used for meat production?
Bacteria: Lactobacillus sp. or pedicoccus
What cell types are used for clean meat production?
Mammalian cells
What is a bioreactor?
- a container or vessel used to grow and cultivate biological organisms, like cells or bacteria, in a controlled environment, often used for research or experimentation
List three types of bioreactors.
- Batch
- Fed batch
- Continuous
Explain batch fermentation.
- closed system with a fixed volume of media, substrate, and all nutrients needed that are added at time ZERO (the time of inoculation)
Explain fed batch fermentation.
- most common
- initial setup same as batch
- nutrients added at set increments
Explain continuous fermentation.
- fresh medium added continuously while used medium and cells are continuously removed and harvested
What is a feedstock?
- feedstocks provide all the necessary nutrients to support effective growth
List 4 things that could be used as a feedstock.
- agriculture and food waste
- spent grain from beer industry
- seaweed
- by-products from ethanol industry
What factors should be considered when choosing a feedstock?
- sustainability
- cost
- variability
- compatibility
What is biomass fermentation? Name one product produced this way.
- the goal is to produce a lot of cells, in which the cells are the product
- Ex. microbial biomass as an alternative protein in the food industry
What is traditional fermentation? Name one example that can be produced this way.
- fermentative microbes use plant-based ingredients as feedstock and the outcome is products with unique flavours, textures, and improved food preservation
- Ex. kimchi, sourdough
What is precision fermentation? Name one example that can be produced this way.
- the use of microbes as cellular factories to produce a specific molecule that will be processed and used as a product
-Ex. Pharmaceutical products
What is single cell protein (SCP)?
- refined edible protein of algal, bacterial, mold, or yeast origin which can be used as animal feed or human food
- the protein is extracted from pure microbial cultures or dead/dried cell biomass
What makes microbial biomass a good alternative protein source?
- include high contents of protein and nutrients, and the process of producing a large amount is inexpensive when considering substrates like agricultural, human, and food waste.
List 2 non-protein products that can be produced during precision fermentation.
- vitamins (B12, riboflavin)
- stevia
- amino acids
List 3 components used in cell culture media.
- nutrients
- growth factors
- animal serum (fetal bovine)
What is a scaffold? Why are they needed in clean meat production?
- micro-carriers (tiny beads) act as microscopic surfaces for cell proliferation
- provides mechanical stability for the growth of cultured cells
- mimics natural tissue architecture, and enables large scale production of clean meat.
Why do cell lines used to produce meat need to be immortalized?
- immortalized cell lines ensure continuous proliferation and long-term cell stability
How does Impossible Foods produce Heme?
- uses yeast that was genetically modified with the gene for soy leghemoglobin and the yeast is grown via fermentation
- soy leghemoglobin which contains Heme, from the yeast is isolated and added to the products that Impossible Meats makes
- when heme combines with other micronutrients, it creates a delicious, meaty flavour
- fermentation allows Heme to be produced in large amounts with low environmental impact
Why are alternative proteins needed in fermentation?
- offer lower environmental impact by conserving land and water and minimizing GHGs.
- to meet various dietary needs and preferences such as vegan, vegetarian, and allergen-free options.
Name 3 advantages of producing protein via fermentation.
- quicker and easy to scale
- inexpensive
- can be done anywhere using food waste, animal/human waste for substrates to feed microbes.
