Fermentation Lab

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Fermentation Lab

• By Amber Cardell

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Fermentation

• Anaerobic cellular respiration
• Occurs when there is no oxidative phosphorylation
  to maintain the production of ATP by glycolysis
• Pyruvate is metabolized into various compounds
  according to what type of fermentation occurs
• Produces only 2 molecules of ATP vs. 36 molecules
  of ATP with aerobic cellular respiration
• The final products of fermentation do not
  generate any energy, but NAD is regenerated and
  fed back into glycolysis.
• The 2 ATPs produced in glycolysis are the only
  energy produced.

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Lactic Acid Fermentation

• uses formation of dairy products and vinegar
• Occurs in bacteria (primarily), some fungi, and
  muscles
• Pyruvate is converted to lactic acid
• Lactic acid accepts the hydrogen from NADH to
  regenerate NAD
• reduces the pH of food which prevents
  acid-sensitive organisms from growing and
  spoiling the food.

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Lactic Acid Fermentation
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Ethanol Fermentation

• Occurs with yeast (primarily) and some bacteria
• Pyruvate is converted into ethanol and CO2
• Uses production of breads and alcoholic
  beverages
• Carboxyl group is removed from pyruvate, forming
  acetaldehyde and releasing CO2 pyruvate
  decarboxylase reaction
• Acetaldehyde is used instead of oxygen to accept
  a hydrogen from NADH to form ethanol and NAD

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Ethanol Fermentation
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Summary of Lactic Acid and Ethanol Fermentation
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Yogurt-making

• The yogurt cultures contain Lactobacillus
  bacteria which convert lactose to lactic acid.
• The acid gives yogurt a sour flavor and causes it
  to curdle.
• There will be about 10,000,000,000 bacteria per
  gram of freshly prepared yogurt!
• Yogurt was first made by Bulgarians thousands of
  years ago and was accredited for their unusually
  long lifespans.

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Soda-making

• Preventing the CO2 from escaping, carbonates the
  soda, and inhibits the pyruvate decarboxylase
  reaction in a negative feedback loop
• The buildup of CO2 inhibits the formation of
  acetaldehyde and thus ethanol
• Wort- the liquid containing plant materials and
  sugars that will be fermented by yeast

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Saccharomyces cerevisiae

• Sacchoaromyces is Greek for sugar mold and
  cerevisiae is Latin for for beer
• Used since ancient times in baking and brewing
• Significant eukaryotic model organism
• First isolated from the skin of grapes
• Flocs and settles well, thus it is easy to filter
  out
• Flocculation- process of coming out of solution
  and clumping together