week 5 - exploiting fungi Flashcards
industrial microorganisms
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
products of interest
primary and secondary metabolites
primary metabolites
produced during active cell growth, usually essential for growth and reproduction
secondary metabolites
are produced near the onset of stationary phase, not essential for growth or reproduction
important considerations
large scale industrial fermentation presents …
several engineering problems
important considerations
industrial fermentors can be..
divided into two major classes, those for anaerobic processes and those for aerobic processes
important considerations
aerobic processes require…
mechanisms for stirring (impeller) and aeration (sparger)
alcoholic beverages are produced by
yeast
from the fermentation of sugar to ethanol and CO2
uses the enzymes pyruvate decarboxylase and alcohol dehydrogenase
beer from fermentation of malted grain (brewing)
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
wine
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
quorn mycoprotein
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)
flavour
bitterness
hydrophobic amino acids (phenylalanine, leucine, isoleucine, methinonine) produced by action of proteolytic enzymes on the milk protein casein
flavour
sulphurous/cabbages
as produced from the conversion of phenylalanine to methanethiol
flavour
sweet
when phenylacetic acid is produced form phenylalanine
flavour
fruity
conversion of leucine to isovaleric acid or production of acetoin
flavour
banana
coversion of leucine to 3-methyl-1-butanol
flavour
malty
conversion of leucine to 3-methyl butanal
flavour
sour
the breakdown of lactose to organic acids
flavour
cheese
cheddar cheese
volatile sulphur compoundss methanethiol, demethyl disulphide and dimethyl trisulphide
fungi in medicine
how did it begin
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
fungi in medicine
kinetics of penicillin fermentation
Penicillium chrysogenum
a few days into growth secondary metabolite penicillin begins to rapidly grow
fungi in medicine
penicillin fermentation
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)
fungi in medicines
statins
reduce cholesterol levels
fungi in medicines
statins
two groups
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
fungi in medicines
how do statins reduce plasma cholesterol levels?
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
fungi in medicines
steroids
microbial biotransformation employs microorganisms to biocatalyse a specific step or steps in an otherwise strictly chemical synthesis
