Transcript living factories

• Biotechnology means using
microbes to make useful
products.
• Microbes include bacteria
and yeast- a fungus.
• Useful products include
bread, beer, wine, human
antibiotics, insulin,
biological detergents.
• Biotechnology is a major
growth industry in Biology.
Yeast
• Yeast is a single-celled
fungus.
nucleus
cytoplasm
cell wall
• It uses sugar as a food
supply
•Yeast reproduces new
cells in a process called
budding
buds
•Word equation
Sugar
carbon dioxide + alcohol + energy
Respiration in Yeast
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Yeast respires glucose to obtain energy.
If oxygen is present it will carry out aerobic respiration,
which releases most of the energy from the glucose.
Aerobic respiration
glucose
+
lots of + carbon
dioxide
energy
oxygen
+ water
If oxygen is not available it will continue to respire
anaerobically, but in doing so receives much less energy.
Anaerobic respiration (fermentation)
glucose
a little
energy
+ carbon
dioxide
+ Alcohol
(ethanol)
Fermentation Experiment
thermometer
Shows release
of heat.
Control – the same
as shown but use
dead yeast
bicarbonate indicator
Detects release
of carbon dioxide.
layer of oil
Oil keeps oxygen out
of yeast and sugar
mixture.
vacuum flask
Prevents heat loss.
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Yeast in boiled and
cooled glucose solution
Boiling removes dissolved
oxygen and kills all
microbes. Cooling prevents
yeast being killed when
added.
Results
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After 2 days;
Experimental
flask
Control
flask
Thermometer
reading
Rises from
20oC to 23oC
No change
Bicarbonate
indicator colour
change
Distillation of liquid
in flask at 80oC
Orange to
yellow
No change
Ethanol
collected
No ethanol
Uses of Yeast
Yeast is used in the baking and brewing industries.
Respiration in yeast releases
bubbles of carbon dioxide
which spread through the
dough, making it rise.
Yeast Ferments
the sugars in fruit
and grains to
produce alcohol.
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Brewing
Brewers Yeast releases energy from
Alcoholic fermentation sugar in the absence of oxygen
(anaerobically) to produce alcohol
The sugars required are obtained from barley grains
during a process called malting.
Malting
Barley grains are soaked in water
for 2 days.
The seeds germinate and the
enzyme amylase changes starch
into sugar.
Endosperm
(starch store)
Embryo
produces
amylase
embryo
Starch
becomes
sugar
Maltings Building
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Effect of germination on barley grains
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dry barley grains
contain starch but
not simple sugar
germinating
seeds need;
barley grains that
have been allowed
to germinate for a
few days contain
simple sugar but
only a little starch
water
oxygen
warmth
Conclusion
Starch is broken down
to simple sugar during
germination
this degradation process is brought about by an enzyme - amylase
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amylase
starch
simple sugar
normally in seed
germination the sugar is
used to provide food for
the developing plant
in brewing the sugar is
used to provide food for
yeast for fermentation
After malting;
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1. The germinated barley grains are ground up with
hot water to make a mash.
2. This is sprayed with hot water to retrieve the
sugars.
3. The sugary liquid is boiled with hops in a wort kettle
to give flavour and remove all unwanted microbes.
4. The resulting mixture (called wort) is cooled, yeast
are then added and grown under ideal conditions in a
fermenter.
5. The resulting beer is allowed to mature in casks.
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growing condition
required by yeast
food supply
suitable temperature
lack of competition
way in which growing
condition is provided
starch converted to sugar for
yeast by germinating barley
grains on floor of malting house
temperature of fermenter vessel
controlled by thermostat
all other micro-organisms killed
by boiling in wort kettle before
yeast is added
Fermenters
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A fermenter is a vessel which can be used to
manufacture a range of products in the presence or
absence of oxygen.
They can be small
and simple ….
… or large and complex –
needing to be monitored
by computer.
Brewing -- Commercial Batch
Processing
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Batch Processing
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This is the technique used by commercial brewers to
provide the best conditions for fermentation.
The common feature of all batch processes is that they
involve closed systems.
After the addition of the raw materials, nutrients and
yeast culture, the system is left untouched, although
controlled, until fermentation ends.
Fermentation ends because nutrients run out or waste
materials build up.
The beer then has to be drawn off and separated from
the yeast, and the fermenter system needs to be
cleaned and sterilised before being re-used. This
wastes time and money.
In brewing, the fermenter is a large copper tank into
which are placed the nutrients and yeast
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Sensors monitor the
pH, temperature and
oxygen concentration
to provide ideal
growing conditions
for the yeast.
( about 10oC – 18oC
and a pH of about 7)
(Respiration
produces heat)
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Immobilisation
Immobilisation involves attaching a cell or enzyme to
another substance so that it can’t move freely.
Whole cells such as yeast can be trapped inside gel
beads.
Enzymes can be attached to glass beads.
enzymes
enzymes attached
to glass bead
Free Yeast
Immobilised Yeast
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Many industries use immobilised cells or enzymes because;
• Products are separated easily and cheaply from cells or
enzymes
• Products are easily purified.
• Less waste as cells / enzymes can be re-used
• Can be used in continuous flow processing
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Commercial Continuous Flow Process
Continuous flow processing
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Raw materials
continuously fed in
Fermenter
vessel
Enzyme (or cell)
immobilised to
glass / gel bead
Glass / gel
bead
Product
continuously
removed
Continuous Flow Process;
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Can be expensive to develop and set up, but;
• Raw materials are continuously added to the
fermenter, so the cells / enzymes receives a steady
stream of raw materials.
• Product does not have to be separated from cells /
enzymes, so money saved.
• Cells / enzymes can be used again, so money saved.
• Valuable time not lost in cleaning out and re-setting
fermenter as in batch processing.
• Less waste and pollution as cells / enzymes not
discarded.
Milk Fermentation by Bacteria
Fresh milk from a cow
contains many bacteria
The bacteria multiply and
make the milk go sour.
Lactose sugar in milk is
broken down by bacteria to
lactic acid
Milk is pasteurised before
we can drink it to remove
harmful bacteria.
Putting the milk in the
fridge slows down the
growth of any remaining
bacteria.
The souring of milk by producing
lactic acid is a “Fermentation process”
Bacteria
Lactose sugar
Lactic Acid
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Making yogurt
• Yogurt relies on the souring of
milk by bacteria.
• The milk is sterilised by
heating
• Bacteria are added
• The bacteria feed on the milk
sugar (lactose) and convert it
to lactic acid , this makes the
milk curdle and go lumpy and
gives yoghurt its sour taste
• Flavourings and colourings are
added to give the final
product.
How Cheese is Made
• Bacteria are added to the
milk to make it go sour.
• Next an enzyme called
rennin is added.
• This breaks down the
proteins in milk and
causes the milk to
separate into solids
(curds) and a liquid
(whey).
The liquid whey is then drained off.
The curd is finally allowed to ripen
and mature to form cheese.
Some cheeses are then flavoured by
adding different microbes.
Blue
stilton