Block C Lecture 3: Exploiting Fungi

Question 1

What are intermediates and end products of anabolism used as?

Answer 1

Cell building blocks or converted to co-enzymes
(Slide 7)

Question 2

What are products of catabolism related to?

Answer 2

Substrate consumption and breakdown
(Slide 7)

Question 3

What is citric acid widely used for?

Answer 3

In the food industry, drinks, sweets, baking and used to treat metal contamination in detergents as a replacement for phosphate
(Slide 8)

Question 4

When was an A. niger citric acid producing strain isolated, and when did production begin?

Answer 4

It was isolated in 1917 and production began in 1919
(Slide 10)

Question 5

Why does industrial production of citric acid by A. niger need a production media which is iron deficient?

Answer 5

As A. niger secretes large amounts of citric acid for use as an iron chelator to scavenge extracellular iron
(Slide 11)

Question 6

What must the stainless steel fermenter vessels used in industrial production of citric acid by A. niger be?

Answer 6

They must be glass lined
(Slide 11)

Question 7

What 2 pathways is citrate produced from in the fungi A. niger?

Answer 7

Glycolysis and the TCA cycle
(Slide 13)

Question 8

How is citrate purified?

Answer 8

By the addition of CaO to the culture broth
(Slide 14)

Question 9

How does the addition to CaO to the culture broth purify citrate?

Answer 9

As it precipitates the citrate as calcium citrate
(Slide 14)

Question 10

After the calcium citrate precipitates are filtered, what is it treated with?

Answer 10

Sulfuric acid
(Slide 14)

Question 11

What 2 things does treating calcium citrate with sulfuric acid yield?

Answer 11

CaSO4 and citric acid
(Slide 14)

Question 12

What occurs after the CaSO4 is filtered out in citric acid product isolation?

Answer 12

The citric acid is crystalised by evaporation
(Slide 14)

Question 13

What are fungi from the Penicillium genus used to ripen?

Answer 13

A variety of cheeses
(Slide 15)

Question 14

What cheese are penicillum roqueforti and penicillum glaucum involved in the production of?

Answer 14

Blue cheese
(Slide 15)

Question 15

What cheeses are Penicillium candidum and Penicillium camemberti used in the production of?

Answer 15

Brie and camembert
(Slide 15)

Question 16

What is quorn?

Answer 16

A meat alternative made of the fungus fusarium venenatum which is grown by fermentation
(Slide 16)

Question 17

What fungi does marmite contain?

Answer 17

Saccharomyces cerevisiae
(Slide 17)

Question 18

What does fermentation do to make bread?

Answer 18

It helps the dough rise
(Slide 18)

Question 19

What does yeast turn sugar into?

Answer 19

Alcohol
(Slide 19)

Question 20

What can Saccharomyces be used to produce?

Answer 20

Ethanol
(Slide 20)

Question 21

What has Saccharomyces yeast been genetically engineered to ferment?

Answer 21

Xylose
(Slide 20)

Question 22

What is the formation of secondary metabolites dependant on?

Answer 22

Growth conditions and media components
(Slide 21)

Question 23

What are secondary metabolites often associated with?

Answer 23

The sporulation process
(Slide 21)

Question 24

What reactions occur to form secondary metabolites?

Answer 24

A number of enzymatic reactions
(Slide 23)

Question 25

During what phase do reactions which form secondary metabolites not occur?

Answer 25

The growth phase
(Slide 23)

Question 26

Where are the starting materials to form secondary metabolites derived from?

Answer 26

Primary metabolism
(Slide 23)

Question 27

What are the best known type of secondary metabolites?

Answer 27

Antibiotics
(Slide 23)

Question 28

Where does the fermentation of antibiotics generally occur in?

Answer 28

Aerobic vessels up to 500,000 litres (though usually 100-150K)
(Slide 24)

Question 29

What is generally automatically controlled in the industrial fermentation of antibiotics?

Answer 29

pH conditions
(Slide 24)

Question 30

What are antibiotics in the industrial fermentation of antibiotics usually grown as?

Answer 30

Fed-batch cultures
(Slide 24)

Question 31

What is the ß-lactam antibiotics class comprised of?

Answer 31

Penicillin and its relatives
(Slide 25)

Question 32

What 2 ways can ß-lactam antibiotics be obtained?

Answer 32

Natural or semi-synthetic
(Slide 25)

Question 33

Why are the semi-synthetic ß-lactam antibiotics preferred?

Answer 33

As they have more desirable pharmaceutical properties as they are more acid stable and resistant to ß-lactamases
(Slide 25)

Question 34

What is flucloxacillin used to treat?

Answer 34

Staphylococcal infections
(Slide 26)

Question 35

What do penicillins target?

Answer 35

Most gram-positive bacteria and some gram-negative cocci
(Slide 26)

Question 36

What is the mechanism of action of penicillins?

Answer 36

They bind to the active sites of PBPs (Penicillin binding proteins) and inactive them, preventing the formation of new peptidoglycan cross-links and weaken the existing cell wall structure
(Slide 26)

Question 37

When are penicillins produced by fungi?

Answer 37

When the carbon source becomes exhausted
(Slide 28)

Question 38

The addition of what 2 things during the production phase of penicillin can extend the phase?

Answer 38

Carbon and nitrogen
(Slide 28)

Question 39

What occurs at the end of the penicillin production process?

Answer 39

Cells are removed by filtration, the pH of the medium is lowered and penicillin is extracted in a solvent and crystallised
(Slide 28)

Question 40

What do Aspergillus terreus and Penicillium citrinum produce?

Answer 40

Statins (lovastatin and mevastatin respectively)
(Slide 29)

Question 41

What produces cyclosporine?

Answer 41

Tolypocladium inflatum
(Slide 29)

Question 42

What is cyclosporine used to treat?

Answer 42

Rheumatoid arthritis, psoriasis, Crohn’s disease, nephrotic syndrome and in organ transplants (to prevent rejection as it’s an immunosuppressant)
(Slide 29)