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Biofuel
Finding more stuff to ferment…
Making ethanol
Cellulose
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Found in the cell walls of plants (wood, fiber,
etc.)
Long chains of glucose, 15 to 10,000
monosaccharides long
Chains are bonded to each other and resistant to
hydrolysis
Rich source of glucose for food and
fermentation, if only we could break it down…
Why can we ferment corn &
potatoes, but not corn stalks?
As if that weren’t difficult enough…
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Cellulose fibers are packed in
crystalline bundles, surrounded
by lignin and hemicellulose to
give the plant strength
Cellulases
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Enzymes (protein catalysts) that break cellulose
into smaller sugars
Found in some bacteria, protists and fungi
Termites digest cellulose from wood with the
help of bacteria and/or protozoans
Cellulases
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Cellulase-producing bacteria in cow stomachs (rumen)
help digest all that grass
Cellulases
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Saprophytic and parasitic fungi produce cellulases to
break down trees on which they are growing
Cellulases
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Endocellulases – break apart cellulose fibers
from each other
Exocellulases – break long chains of cellulose
into disaccharides
Cellobiase – breaks disaccharides into glucose