Bioprocess

Question 1

What are the main advantages of bio processes

Answer 1

• High bio reaction rates
• High energetic efficiency
• Cells possess large portfolios of catalyst types

Question 2

What are main disadvantages of bioprocesses

Answer 2

• Commonly fastidious (very sensitive) in terms of operating conditions
• Natural controls of overproduction are complex & highly efficient
• Products are commonly unstable and initially dilute

Question 3

What happens in fermentation systems?

Answer 3

• uses microorganisms to convert one substance to another
• heart of a typical bioprocess
• batch or fed batch process
• after fermentation product must be recovered and purified

Question 4

Why are continuous processes generally not used for fermentation?

Answer 4

Creates reliability issues

However, it is starting to be used-more efficient and cost effective if automated

Question 5

Give some methods of purifying bio products

Answer 5

• distillation
• centrifugation
• filtration

Question 6

What are the steps of fermenter scale up

Answer 6

Stock culture
Shaker flask
Pre-seed and seed fermenters
Production fermentor

Question 7

Why does steam enter and mix with product exiting a fermentor?

Answer 7

It is used to sterilise

-non corrosive, easy to use and can easily be monitored

Question 8

What does a sparger do in a fermenter

Answer 8

Introduces air into fermentor to give sufficient oxygen for microorganisms

Fine bubbles are used due to greater surface area-better oxygen transfer

Air should be filtered

Question 9

What are baffles, fermentor?

Answer 9

-metal strips that prevent whirling masses of fluid forming at vessel walls

Question 10

Why is agitation useful, fermentor?

Answer 10

Provides uniform suspension of cells in homogeneous nutrient medium

Provides build fluid and gas phase mixing

Question 11

How is agitation achieved, fermentor?

Answer 11

With an impeller

Mixed cells and gases bubbles through medium

Question 12

Give examples of where sterilisation must be used with a fermentor

Answer 12

• initial sterile environment, heat
• pure inoculum
• sterile feeds e.g air
• sterile culture media
• aseptic conscious plant operators (highly trained)

Question 13

How do you prevent contamination from operators

Answer 13

• sterile air supply under positive pressure, air changes several times per hour
• UV lighting
• sterile clothing and special washing procedure
• washing of floors and walls with antiseptic solutions

Question 14

What are the five major groups of commercially important fermentations?

Answer 14

Produces microbial cells

Produces microbial enzymes

Produces microbial metabolites

Produces recombinant products

Modification of a compound, transformation process

Question 15

What is batch process like, in terms of medium and nutrients/substrate etc

Answer 15

• closed system other than aeration
• limited amount of medium
• all nutrients/substrate are added at beginning

Question 16

What is fed-batch process like, in terms of nutrients/substrate etc

Answer 16

Substrate is fed in during process to extend duration of culture:
-produce higher cell densities
Or
-switch metabolism to produce recombinant dna for example

Question 17

What is continuous process like, in terms of medium, nutrients/substrate etc

Answer 17

• open system
• medium is continuously added and an equal volume of fermented medium is removed simultaneously
• organisms are fed with fresh nutrients and spent cells are removed
• steady state which can last up to months