Block C Lecture 3: Exploiting Fungi Flashcards
What are intermediates and end products of anabolism used as?
Cell building blocks or converted to co-enzymes
(Slide 7)
What are products of catabolism related to?
Substrate consumption and breakdown
(Slide 7)
What is citric acid widely used for?
In the food industry, drinks, sweets, baking and used to treat metal contamination in detergents as a replacement for phosphate
(Slide 8)
When was an A. niger citric acid producing strain isolated, and when did production begin?
It was isolated in 1917 and production began in 1919
(Slide 10)
Why does industrial production of citric acid by A. niger need a production media which is iron deficient?
As A. niger secretes large amounts of citric acid for use as an iron chelator to scavenge extracellular iron
(Slide 11)
What must the stainless steel fermenter vessels used in industrial production of citric acid by A. niger be?
They must be glass lined
(Slide 11)
What 2 pathways is citrate produced from in the fungi A. niger?
Glycolysis and the TCA cycle
(Slide 13)
How is citrate purified?
By the addition of CaO to the culture broth
(Slide 14)
How does the addition to CaO to the culture broth purify citrate?
As it precipitates the citrate as calcium citrate
(Slide 14)
After the calcium citrate precipitates are filtered, what is it treated with?
Sulfuric acid
(Slide 14)
What 2 things does treating calcium citrate with sulfuric acid yield?
CaSO4 and citric acid
(Slide 14)
What occurs after the CaSO4 is filtered out in citric acid product isolation?
The citric acid is crystalised by evaporation
(Slide 14)
What are fungi from the Penicillium genus used to ripen?
A variety of cheeses
(Slide 15)
What cheese are penicillum roqueforti and penicillum glaucum involved in the production of?
Blue cheese
(Slide 15)
What cheeses are Penicillium candidum and Penicillium camemberti used in the production of?
Brie and camembert
(Slide 15)
What is quorn?
A meat alternative made of the fungus fusarium venenatum which is grown by fermentation
(Slide 16)
What fungi does marmite contain?
Saccharomyces cerevisiae
(Slide 17)
What does fermentation do to make bread?
It helps the dough rise
(Slide 18)
What does yeast turn sugar into?
Alcohol
(Slide 19)
What can Saccharomyces be used to produce?
Ethanol
(Slide 20)
What has Saccharomyces yeast been genetically engineered to ferment?
Xylose
(Slide 20)
What is the formation of secondary metabolites dependant on?
Growth conditions and media components
(Slide 21)
What are secondary metabolites often associated with?
The sporulation process
(Slide 21)
What reactions occur to form secondary metabolites?
A number of enzymatic reactions
(Slide 23)
During what phase do reactions which form secondary metabolites not occur?
The growth phase
(Slide 23)
Where are the starting materials to form secondary metabolites derived from?
Primary metabolism
(Slide 23)
What are the best known type of secondary metabolites?
Antibiotics
(Slide 23)
Where does the fermentation of antibiotics generally occur in?
Aerobic vessels up to 500,000 litres (though usually 100-150K)
(Slide 24)
What is generally automatically controlled in the industrial fermentation of antibiotics?
pH conditions
(Slide 24)
What are antibiotics in the industrial fermentation of antibiotics usually grown as?
Fed-batch cultures
(Slide 24)
What is the ß-lactam antibiotics class comprised of?
Penicillin and its relatives
(Slide 25)
What 2 ways can ß-lactam antibiotics be obtained?
Natural or semi-synthetic
(Slide 25)
Why are the semi-synthetic ß-lactam antibiotics preferred?
As they have more desirable pharmaceutical properties as they are more acid stable and resistant to ß-lactamases
(Slide 25)
What is flucloxacillin used to treat?
Staphylococcal infections
(Slide 26)
What do penicillins target?
Most gram-positive bacteria and some gram-negative cocci
(Slide 26)
What is the mechanism of action of penicillins?
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)
When are penicillins produced by fungi?
When the carbon source becomes exhausted
(Slide 28)
The addition of what 2 things during the production phase of penicillin can extend the phase?
Carbon and nitrogen
(Slide 28)
What occurs at the end of the penicillin production process?
Cells are removed by filtration, the pH of the medium is lowered and penicillin is extracted in a solvent and crystallised
(Slide 28)
What do Aspergillus terreus and Penicillium citrinum produce?
Statins (lovastatin and mevastatin respectively)
(Slide 29)
What produces cyclosporine?
Tolypocladium inflatum
(Slide 29)
What is cyclosporine used to treat?
Rheumatoid arthritis, psoriasis, Crohn’s disease, nephrotic syndrome and in organ transplants (to prevent rejection as it’s an immunosuppressant)
(Slide 29)
