Introduction To Biotechnology

Question 0

Describe the scope of biotechnology

Answer 0

1) prevention of spoilage of raw materials and manufactured products (timber, paint, sulphate-reducing bacteria, food spoilage)
2) protection of the environment (degradation of oil spills, removal of toxic heavy metals)
3) promotion of growth and metabolic activity of organisms (fermentation industry, microbially-processed foods etc)
4) genetic engineering of bacteria, plants and animals (engineering of plants to be herbicide, virus and insect resistant, mammalian and plant tissue cultures)
5) medical biotechnology (recombinant vaccines, medical diagnostics, genetic disease identification etc)
6) genetic information gathering (genome sequencing projects)

Question 1

What is biotechnology?

Answer 1

The deliberate and controlled application of biological organisms, systems or processes (ie. living or dead cells, cell components- enzymes) in technically useful operations either in the manufacturing or service industries.

Question 2

Name one bacterium and one eukaryote that have had their genomes sequenced

Answer 2

Haemophilus influenzae,

Sacchromyces cerevisiae

Question 3

Name different types of industrial fermentation

Answer 3

Microbial biomass
Primary metabolites
Secondary metabolites
Antibiotics
Polysaccharides
Microbial conversions
Food fermentations
Bio leaching of minerals from ore
Cloned mammalian products for therapy

Question 4

Give examples of microbial biomass fermentations

Answer 4

Food yeasts (Torula) and bakers yeast (S. cerevisiae)
Bacterial insecticides (Bacillus thuringiensis)
Single cell proteins

Question 5

What is the difference between primary and secondary metabolites?

Answer 5

Primary: intermediates and end products of the primary metabolic pathways are produced.
Secondary: products that are produced after active growth has stopped - ie. in stationary phase.

Question 6

Give examples of cloned mammalian therapies

Answer 6

Human insulin (previously pig insulin which differs by 1 amino acid)
Human growth hormones
Interferon, interleukin-2

Question 7

Name the operations in biotechnology

Answer 7

Culture choice
Large scale cultivation
Obtaining the desired cell responses
Operation of the process
Product recovery

Question 8

Describe the two processes in culture choice

Answer 8

Culture improvement: once a useful organism has emerged, it is important to improve its productivity. The medium and fermentation conditions have to be optimised and the performance of the bug itself is improved by mutation, selection and genetic manipulation.
Culture maintenance: the ability to conserve and grow cultures at will is essential. The culture can be dried on sterile loam sand or other substrate, stored on nutrient agar slants or in liquid media, freeze-dried (lyophilise) and stored in a vacuum or stored as vegetative cells, arthrospores or conidia in liquid nitrogen or in vapour phase of liquid nitrogen.

Question 9

What is NB about large scale cultivation and what factors affect it?

Answer 9

It has to include new concepts for dealing with problems that are specific to large scale operations. The volume of the inoculum is 10% for actinomycetes and fungi and 3% for non-actinomycete bacteria. Bio reactors, growth media, sterilisation, aeration and cooling are imporwnt

Question 10

What is fermentation engineering?

Answer 10

Deals with the design, development, construction and operation of the factory and all equipment used in a large scale bio technological process.

Question 11

What is a bioreactor and a fermenter?

Answer 11

Bioreactor: a vessel in which materials are treated to promote their biochemical transformation by the action of living cells/cellular components.
A fermenter is a bioreactor in which cell growth is promoted/maintained to allow formation of products.

Question 12

What is the purpose of the agitator/impellers?

Answer 12

They ensure mixing so that the culture is homogenous, they disperse the air bubbles efficiently as they emerge from the sparger, they ensure that any additions to the culture are rapidly mixed into the culture.

Question 13

What is the function of the baffles?

Answer 13

They are there to disrupt the smooth liquid flow around the fermenter- create turbulence- which helps with mixing of the culture and with dissolution of oxygen form the air bubbles into the bulk culture

Question 14

What is the purpose of the headspace?

Answer 14

The space above the culture allows droplets carried out of the bulk culture by the airflow to disentrain efficiently from the air and dribble back into the culture before the air reaches the exhaust valve.

Question 15

Describe how a stirred tank fermenter works

Answer 15

Air is introduced at the bottom by the sparge. As the bubbles move up through the culture, the agitator impellers mixes the culture, breaks up the bubbles and maintains the pH. The heating/cooling coils moving through the culture and the cooling jacket have constant cool water moving through them to cool the culture.
The problem with the coils is they make the fermenter cluttered and makes it harder to clean.
The turbulence in the fermenter is created by the air sparge, impellers and baffle plates

Question 16

Describe the air-lift fermenter and the bubble-column fermenter

Answer 16

Air lift fermenter: by adding air into the inner draught tube, the density decreases so the culture moves up through the tube and out the sides (thereby mixing itself without needing impellers).
Bubble column: air is sparged into the bottom, bubbles move up and break into tiny bubbles as they move through the baffle plates

Question 17

Explain batch fermentation

Answer 17

The fermenter is charge with medium and inoculated. A the cell growth proceeds, conditions in the fermenter change (nutrients consumed and products formed). Once the required degree of growth/product formed is reached, fermenter is discharged and cleaned.
Is a non-steady state process as cell growth changes

Question 18

Explain continuous fermentation

Answer 18

Fresh reagents flow into the fermenter continuously as culture is removed at the same set rate (culture volume remains constant). It is a steady state process as cells maintain a constant growth rate.
One of the nutrients in the medium feed had to be at a GROWTH-LIMITING concentration.

Question 19

Why is sterilisation important?

Answer 19

To ensure that a process is carried out with only the desired organism, permit safe use of the product, avoid contamination of the environment and to prevent spoilage of a product

Question 20

What is the Maillard reaction?

Answer 20

Oxidation of phenolic compounds (thermal degradation of nutrients can occur so decreases nutrient value of medium which decreases cell growth)

Question 21

Describe the difference of sterilisation in batch processes vs continuous processes

Answer 21

Batch processes: heat sterilisation causes a pH drift decrease (more acidic) so pH adjustment is usually required
Continuous: is rapid (so quality of medium is improved- shorter process time). It requires rapid heating, holding time at sterilisation temperature and rapid cooling

Question 22

Why must oxygen be continuously sparged into the medium?

Answer 22

Oxygen has a low solubility in liquids so it cannot be supplied in the medium with the nutrients

Question 23

Why is product recovery an acute problem?

Answer 23

The product produced is in very dilute concentrations and because of the form in which the product is first presented- cell lysis is required to obtain an intracellular product.

Question 24

What is downstream processing and what steps are required?

Answer 24

Describes all the steps to recover useful products from any kind of industrial process.
Separation of particles (filtration, centrifugation, flocculation)
Disintegration of cells
Extraction of products (serves to separate and concentrate products from bulk liquid)
Concentration methods (extraction, membrane filtration, ion exchange)
Purification of mixtures
Drying