3&4. Bioprocesses

Question 1

Bioprocess

Answer 1

Any process that uses the growth of complete living cells or their components to obtain desired products

Question 2

Industrial fermentation

Answer 2

Any process that uses microorganisms at a large scale in an industrial setting

Question 3

Fermentor (bioreactor)

Answer 3

Machine that processes organic matter into biomass, which can be used as fuel in a Bio Gas engine or Bio Generator

Question 4

Upstream processing

Answer 4

All the steps in a fermentation process starting from coming up with the idea to obtaining the raw (unpurified) product

Question 5

Downstream processing

Answer 5

All the steps in a fermentation process starting from purifying the product to commercialization

Question 6

Seed stock

Answer 6

The original stock from which we obtain all the microorganisms we use in a fermentation process

Question 7

Work strains

Answer 7

Duplicates of the seed stock that we use in day to day work

Question 8

Components of a fermentation medium

Answer 8

Water
Carbon source
Macronutrients
Micronutrients
Growth factors (if the microbe requires it)
Optional: anti-foaming agents, metabolic precursors, virus inhibitors

Question 9

Feedstock

Answer 9

Substrates that we use to provide nutrients to the fermentation medium

Question 10

How do we choose a carbon source for the fermentation medium?

Answer 10

We use the cheapest option that our target microorganism can use

Question 11

Types of carbon sources

Answer 11

Glucose, sucrose
Lactose
Starch
Cellulose
Vegetable oils
Ethanol

Question 12

How do we balance the pH after adding nitrogen sources (they’re usually basic)?

Answer 12

We add buffers
Sodium biphosphate or monopotassium phosphate

Question 13

Fermentation “modes”

Answer 13

The way we add nutrients to the medium
1. Batch
2. Continuous
3. Fed-batch

Question 14

Batch mode

Answer 14

We use only the fermentation medium we started with, we do not add anything

Question 15

Continuous mode

Answer 15

We continuously add sterile medium to the tank and remove the product

Question 16

Fed-batch mode

Answer 16

We intermittently add nutrients to the fermentation medium in order to avoid nutrient deficiency and catabolite repression

Question 17

Catabolite repression

Answer 17

If we add too much glucose initally, that will be the only carbon source that the microbes use, greatly diminishing the productivity of the fermentation

Question 18

Phases of microbial growth

Answer 18

Lag phase: population is not growing yet
Exponential phase: primary metabolites are produced
Stationary phase (idiophase): secondary metabolites are produced as population plateaus
Death

Question 19

Primary metabolites

Answer 19

Essential for the continued growth of the microbe (amino acids, nucleotides…)

Question 20

Secondary metabolites

Answer 20

Non-essential for growth (antibiotics)

Question 21

If you want to improve antibiotic synthesis, what mode would you use and how?

Answer 21

Fed-batch
Add the limiting nutrient during idiophase (usually glucose)

Question 22

Mesophiles

Answer 22

Grow between 20-40 C
E coli and saccharomyces

Question 23

Thermophiles

Answer 23

Grow at between 45-65 C

Question 24

Psychotrophs

Answer 24

Grow at 0-15 C

Question 25

Downstream processing steps for an intracellular product

Answer 25

Cell-medium separation
Cell concentration
Cell lysis
Extraction
Purification

Question 26

Downstream processing steps for an extracellular product

Answer 26

Cell-medium separation
Extraction
Purification

Question 27

Common methods for cell-medium separation

Answer 27

Centrifugation
Sedimentation
Ultrafiltration
Coagulation/flocculation

Question 28

Coagulation (as a cell-medium separation method)

Answer 28

Same as sedimentation, but a coagulant is added to cause cells to aggregate, making the process faster

Question 29

Ultrafiltration

Answer 29

0,2 micrometer filters that separate cells and medium

Question 30

Methods for cell disruption (lysis)

Answer 30

Pressure
Sonication
Enzymatic

Question 31

Pressure (as a cell-lysis method)

Answer 31

Create an environment of high pressure and suddenly release it. Cells are resistant to increases in pressure, but not so much decreases in pressure. The sudden release will cause them to rupture from expanding too quickly

Question 32

Methods for product extraction

Answer 32

Extraction with organic solvents
Precipitation with ammonium sulfate

Question 33

Methods for product purification

Answer 33

Electrophoresis
Isoelectric focusing
Chromatography