week 5 - exploiting fungi

Question 1

industrial microorganisms

Answer 1

must produce the product of interest in high yield

most grow rapidly on inexpensive culture media

should be amenable to genetic manipulation

if possible should be nonpathogenic

Question 2

products of interest

Answer 2

primary and secondary metabolites

Question 3

primary metabolites

Answer 3

produced during active cell growth, usually essential for growth and reproduction

Question 4

secondary metabolites

Answer 4

are produced near the onset of stationary phase, not essential for growth or reproduction

Question 5

important considerations
large scale industrial fermentation presents …

Answer 5

several engineering problems

Question 6

important considerations

industrial fermentors can be..

Answer 6

divided into two major classes, those for anaerobic processes and those for aerobic processes

Question 7

important considerations
aerobic processes require…

Answer 7

mechanisms for stirring (impeller) and aeration (sparger)

Question 8

alcoholic beverages are produced by

Answer 8

yeast

from the fermentation of sugar to ethanol and CO2

uses the enzymes pyruvate decarboxylase and alcohol dehydrogenase

Question 9

beer from fermentation of malted grain (brewing)

Answer 9

malt prepared from germinated, that digest starch grains and convert it to sugars

then yeast can use the sugars for fermentation

for ‘top fermenting’ use S. cerevisiae to make ales
- warmer temps

for ‘bottom fermenting’ use S. carlsbergensis to make larger
- cooler temps

Question 10

wine

Answer 10

is produced by fermentation of grape juice

use Saccharomyces ellipsoideus

dry wines - the sugars are virtually all fermented

sweet wine - some sugars remain

sparkling wine - production of CO2 from a final fermentation

Question 11

quorn mycoprotein

Answer 11

use filamentous fungus Fusarium venenatum

the hyphae provide similar texture to muscle fibres in meat

the hyphae contain 45-50% protein

low in cholesterol and fat

low carbon footprint

production is limit by appearance by hyperbranched variant in the culture (about 1 month)

Question 12

flavour
bitterness

Answer 12

hydrophobic amino acids (phenylalanine, leucine, isoleucine, methinonine) produced by action of proteolytic enzymes on the milk protein casein

Question 13

flavour
sulphurous/cabbages

Answer 13

as produced from the conversion of phenylalanine to methanethiol

Question 14

flavour
sweet

Answer 14

when phenylacetic acid is produced form phenylalanine

Question 15

flavour
fruity

Answer 15

conversion of leucine to isovaleric acid or production of acetoin

Question 16

flavour
banana

Answer 16

coversion of leucine to 3-methyl-1-butanol

Question 17

flavour
malty

Answer 17

conversion of leucine to 3-methyl butanal

Question 18

flavour
sour

Answer 18

the breakdown of lactose to organic acids

Question 19

flavour
cheese

Answer 19

cheddar cheese

volatile sulphur compoundss methanethiol, demethyl disulphide and dimethyl trisulphide

Question 20

fungi in medicine
how did it begin

Answer 20

the industrial production of antibiotics begins with screening for antibiotic producers

• penicillin produced by P. chrysogenum
• Cephalosporin produced by Cephalosporium species
• both are beta-lactams

Question 21

fungi in medicine
kinetics of penicillin fermentation

Answer 21

Penicillium chrysogenum

a few days into growth secondary metabolite penicillin begins to rapidly grow

Question 22

fungi in medicine
penicillin fermentation

Answer 22

penicillin fermentation –> natural penicillins (e.g. penicillin G)

chemical or enzmatic treatment of penicillin G
–> 6-aminopenicillanic acid

add side chains chemically –> semisynthetic penicillin (for example ampicillin, amoxycillin, methicillin)

Question 23

fungi in medicines
statins

Answer 23

reduce cholesterol levels

Question 24

fungi in medicines
statins
two groups

Answer 24

fermentation-derived e.g. simvastaiin, prevastain from Penicillium citrinum and other fungi

synthetic e.g. fluvastatin

fermentation-derived statins appear more effective in reducting LDLs (low density lipoproteins) but no clear explanation has accounted for this phenomenon

Question 25

fungi in medicines
how do statins reduce plasma cholesterol levels?

Answer 25

statins are competitive inhibitors of 3-HMG-CoA reductase, a key enzyme in cholesterol biosynthesis

they work to inhibit CoA to block production of cholesterol

Question 26

fungi in medicines
steroids

Answer 26

microbial biotransformation employs microorganisms to biocatalyse a specific step or steps in an otherwise strictly chemical synthesis