PART 3

Question 1

Types of Reactor

Answer 1

Batch and Chemostat (CSTR)

Question 2

_________: changing conditions - transient (S, X, growth rate), high initial substrate, different phases of growth.

Answer 2

Batch

Question 3

________: steady-state, constant low concentration of substrate, constant growth rate that can be set by setting the dilution rate (ie. the feed flow rate).

Answer 3

Chemostat

Question 4

__________ is more efficient.·

Answer 4

Chemostat

Question 5

____________ is more common.

Answer 5

Batch

Question 6

CHOICE OF CONTINUOUS VS
BATCH PRODUCTION

Answer 6

Productivity
Flexibility
Control
Genetic stability
Operability
Economics
Regulatory

Question 7

_________: rate of product per time per volume. Chemostat is better for growth-associated products. Wasted time in batch process.

Answer 7

Productivity

Question 8

____________: the ability to make more than one product with the same reactor. Batch better.

Answer 8

Flexibility

Question 9

___________: maintaining the same conditions for all of the products produced. In theory, the chemostat is better, steady state. In reality???

Answer 9

Control

Question 10

____________: maintaining the organism with the desired characteristics. Chemostat selects for fast-growing mutants that may not have the desired characteristics.

Answer 10

Genetic stability

Question 11

___________: maintaining a sterile system. Batch better.

Answer 11

Operability

Question 12

____________: validating the process. Initially, many process batch, too expensive to re-validate after clinical trials.

Answer 12

Regulatory

Question 13

Consider the production of a growth-associated product (like cell mass) in _________.

Answer 13

suspension culture

Question 14

__________ of a chemostat is detrimental to engineered organisms.

Answer 14

Selective pressure

Question 15

_______ is more mechanically reliable.

Answer 15

Batch

Question 16

_______ system is more more flexible.

Answer 16

Batch

Question 17

SPECIALIZED REACTORS

Answer 17

Chemostat with recycle
Multistage chemostat
Fed-batch
Perfusion

Question 18

Can we operate a chemostat with a dilutio rate greater than
maximum growth rate?

Why or why not?

Answer 18

No

Because the cell growth cannot keep up with how fast the cells are removed from the reactor, and after some time the cells would washout of the reactor.

Question 19

What conditions would we want to opera a chemostat with a dilution rate higher than the maximum growth rate?

Answer 19

We want a high dilution rate when we have a high volume of feed with a low concentration of substrate. Waste water treatment has these characteristics.

Question 20

Chemostats ___________ if µmax <D. Higher dilution rates can be achieved with recycling.

Answer 20

cannot be operated

Question 21

Recombinant product under the control of an inducible promoter.

Answer 21

Special Cases - Chemostat

Question 22

_______________ grow at the same rate if the recombinant product is not expressed.
If the recombinant product is expressed, the ___________________.

Answer 22

Recombinant strain and wild type

recombinant strain grows much slower

Question 23

First chemostat is fed with a non-inducing growth substrate, allowing the recombinant strain to be produced.

The effluent from the first chemostat feeds a second chemostat that is fed inducer, and the product is produced.

Note: new recombinant cells are continually added to the second chemostat not allowing take-over by a fast growing mutant.

Answer 23

MULTISTAGE CHEMOSTAT

Question 24

_________ gain some advantages of a CSTR, retain some disadvantages of batch.

Answer 24

Fed-batch reactors

variable volume batch reactor

Question 25

Reduces substrate inhibition or catabolic repression, allows for high conversion, and the extension of stationary phase. Semi-batch nature usually leads to higher operation cost and batch variability.

Answer 25

Fed-batch Operation

Question 26

____________ are started as batch cultures and grown to an initial cell concentration X, after which fed-batch operation begins.

Answer 26

Fed-batch cultures

Question 27

Usually, fed-batch cultures are taken through many feeding cycles, with each feeding cycle followed by a harvest cycle during which the volume is drawn back down to Vo and the cycle begun again.

Answer 27

Repeated Fed-batch

Question 28

Substrate is consumed at the same rate it is added.

Answer 28

QUASI-STEADY STATE

Question 29

PERFUSION CULTURE

Answer 29

Animal Cell culture Constat medium flow Cell retention Selective removal of dead cells Removal of cell debris, inhibitory by products High medium use, costs raw materials and sterilization.